Download to read offline
![18 Introduction
into a single network architecture even if we start from a so-called clean slate.
Moreover, clean-slate design of an existing network as large and complex as
the Internet is not really a practical option, and any practical attempt to upgrade
functionality must eventually consider factors such as backward compatibility,
evolutionary upgrade of equipment, equipment cost, software complexity, and
so on. However, the top-down clean-slate design methodology described in this
book is expected to be beneficial because it exposes key requirements and design
issues without being constrained by current practices. Although a single new
Internet protocol is unlikely to emerge from this methodology, it may be expected
that researchers will design and validate several of the key network capabilities
outlined in Section 1.5, and eventually some of these ideas will migrate into the
mainstream Internet protocol. In the chapters that follow, we will explore the
details of protocol design for each of the emerging wireless service scenarios
outlined in this introductory chapter. In the concluding chapter, we will briefly
discuss a roadmap to the future, including some strategies for how to put all
these ideas together into a unified network architecture.
References
[1] Raychaudhuri, D. and Gerla, M. 2005. New Architectures and Disruptive Tech-
nologies for the Future Internet: The Wireless, Mobile and Sensor Network Per-
spective. Report of NSF Wireless Mobile Planning Group (WMPG) Workshop.
http://www.winlab.rutgers.edu/WMPG
[2] Perkins, C. 1998. Mobile IP. IEEE Communications Magazine, 35(5), 84–86, 91–99.
[3] Akyildiz, I., Wang, X., and Wang, W. 2005. Wireless Mesh Networks: A Survey,
Computer Networks. Computer Networks and ISDN Systems, March.
[4] Lamming, M. and Bohm, D. 2003. SPECs: Another Approach to Human Context and
Activity Sensing Research, Using Tiny Peer-to-Peer Wireless Computers. Lecture
Notes in Computer Science, October.
[5] Fall, K. 2003. A Delay Tolerant Network Architecture for Challenged Internets. ACM
SigComm.
[6] Culler, D., Estrin, D., and Srivastava, M. 2004. Guest Editors’ Introduction: Overview
of Sensor Networks. IEEE Computer Magazine, August.
[7] Zanella, A., Fasolo, E., Padova, C., Chiasserini, F., Meo, M., Torino, M., Frances-
chinis, M., and Spirito, A. 2006. Inter-vehicular communication networks. Second
Internal NEWCOM Workshop.
[8] Rappaport, T. 2002. Wireless Communications: Principles and Practices. Second ed.
Prentice Hall.
[9] Rosenberg, J. et al. 2002. SIP: Session Initiation Protocol. Internet Engineering Task
Force RFC 3261.
[10] Perkins, C., and Belding-Royer, E. 2003. Ad hoc On-Demand Distance Vector
(AODV) Routing. Internet Engineering Task Force, RFC 3561.](https://image.slidesharecdn.com/40616-250302223138-ac717f58/75/Emerging-Wireless-Technologies-and-the-Future-Mobile-Internet-1st-Edition-Dipankar-Raychaudhuri-38-2048.jpg)
![Vatican.] [Photograph by Anderson.
THE NILE.
AN EXAMPLE OF ALEXANDRIAN ART.
As soon as she had arrived she ordered her bath to be prepared,
and having been washed and scented, her hair being carefully
plaited around her head, she lay down upon a couch and partook of
a sumptuous meal. After this she wrote a short letter to Octavian,
asking that she might be buried in the same tomb with Antony; and,
this being despatched, she ordered everybody to leave the
mausoleum with the exception of Charmion and Iras, as though she
did not wish to be disturbed in her afternoon’s siesta. The doors
were then closed, and the sentries mounted guard on the outside in
the usual manner.
When Octavian read the letter which Cleopatra’s messenger had
brought him, he realised at once what had happened, and hastened](https://image.slidesharecdn.com/40616-250302223138-ac717f58/75/Emerging-Wireless-Technologies-and-the-Future-Mobile-Internet-1st-Edition-Dipankar-Raychaudhuri-69-2048.jpg)
More Related Content
Similar to Emerging Wireless Technologies and the Future Mobile Internet 1st Edition Dipankar Raychaudhuri
Emerging Wireless Technologies and the Future Mobile Internet 1st Edition Dipankar Raychaudhuri
- 1. Visit https://ebookultra.com todownload the full version and explore more ebooks Emerging Wireless Technologies and the Future Mobile Internet 1st Edition Dipankar Raychaudhuri _____ Click the link below to download _____ https://ebookultra.com/download/emerging-wireless- technologies-and-the-future-mobile-internet-1st- edition-dipankar-raychaudhuri/ Explore and download more ebooks at ebookultra.com
- 2. Here are somesuggested products you might be interested in. Click the link to download Mobile and Wireless Communications Key Technologies and Future Applications Peter Smyth https://ebookultra.com/download/mobile-and-wireless-communications- key-technologies-and-future-applications-peter-smyth/ Advanced Wireless Communications Internet Future Evolving Technologies Third Edition Savo G Glisic https://ebookultra.com/download/advanced-wireless-communications- internet-future-evolving-technologies-third-edition-savo-g-glisic/ Fixed Mobile Wireless Networks Convergence Technologies Solutions Services 1st Edition Joseph Ghetie https://ebookultra.com/download/fixed-mobile-wireless-networks- convergence-technologies-solutions-services-1st-edition-joseph-ghetie/ Nexus Analysis Discourse and the Emerging Internet 1st Edition Ron Scollon https://ebookultra.com/download/nexus-analysis-discourse-and-the- emerging-internet-1st-edition-ron-scollon/
- 3. Broadband Mobile MultimediaTechniques and Applications Wireless Networks and Mobile Communications 1st Edition Yan Zhang https://ebookultra.com/download/broadband-mobile-multimedia- techniques-and-applications-wireless-networks-and-mobile- communications-1st-edition-yan-zhang/ Wireless Power Transfer Technologies Theory and technologies 2nd Edition Professor Naoki Shinohara https://ebookultra.com/download/wireless-power-transfer-technologies- theory-and-technologies-2nd-edition-professor-naoki-shinohara/ Mobile and Wireless Communications An Introduction 1st Edition Gordon Gow https://ebookultra.com/download/mobile-and-wireless-communications-an- introduction-1st-edition-gordon-gow/ The Internet and Mobile Technology 1st Edition Marvin Zelkowitz Ph.D. Ms Bs. https://ebookultra.com/download/the-internet-and-mobile- technology-1st-edition-marvin-zelkowitz-ph-d-ms-bs/ Public Engagement and Emerging Technologies 1st Edition Kieran O'Doherty https://ebookultra.com/download/public-engagement-and-emerging- technologies-1st-edition-kieran-odoherty/
- 5. Emerging Wireless Technologiesand the Future Mobile Internet 1st Edition Dipankar Raychaudhuri Digital Instant Download Author(s): Dipankar Raychaudhuri, Mario Gerla ISBN(s): 9780521116466, 0521116465 Edition: 1 File Details: PDF, 4.32 MB Year: 2011 Language: english
- 7. Emerging Wireless Technologiesand the Future Mobile Internet This book provides a preview of emerging wireless technologies and their architectural impact on the future mobile Internet. The reader will find an overview of architectural considerations for the mobile Internet, along with more detailed technical discussion of new protocol concepts currently being considered at the research stage. The first chapter starts with a discussion of anticipated mobile/wireless usage scenarios, leading to an identification of new protocol features for the future Internet. This is followed by several chapters that provide in-depth coverage on next-generation wireless standards, ad hoc and mesh network protocols, opportunistic delivery and delay-tolerant networks, sensor network architectures and protocols, cognitive radio networks, vehicular networks, security and privacy, and experimental systems for future Internet research. Each of these contributed chapters includes a discussion of new networking requirements for the wireless scenario under consideration, architectural concepts, and specific protocol designs, many still at the research stage. Dipankar Raychaudhuri is Professor-II, Electrical and Computer Engineering and Direc- tor, Wireless Information Network Lab (WINLAB) at Rutgers University. WINLAB’s research scope includes topics such as RF (Radio Frequency)/sensor devices, cognitive radio, dynamic spectrum access, 4G systems, ad hoc mesh networks, wireless security, future Internet architecture, and pervasive computing. Raychaudhuri is widely recog- nized as a leader in the future Internet research field and has lectured extensively on the topic at both national and international forums. During 2005–2007, he organized and co-hosted the NSF (National Science Foundation) “Wireless Mobile Planning Group” (WMPG) workshops that inspired and set the stage for much of the content in this book. Mario Gerla is a Professor in the Computer Science Department at the University of California, Los Angeles. He has led the ONR (Office of Naval Research) MINUTEMAN (Multimedia Intelligent Network of Unattended Mobile Agents) project, designing the next-generation scalable airborne Internet for tactical and homeland defense scenar- ios and two advanced wireless network projects under U.S. Army and IBM funding. Dr. Gerla is an active participant in future Internet research activities in the United States, co-hosting the NSF WMPG workshops from 2005 to 2007. His research group is an active contributor to the emerging field of vehicular networking and is credited with the “CarTorrent” protocol for peer-to-peer file transfer between vehicles.
- 9. Emerging Wireless Technologies andthe Future Mobile Internet Edited by DIPANKAR RAYCHAUDHURI WINLAB, Rutgers University MARIO GERLA University of California, Los Angeles
- 10. CAMBRIDGE UNIVERSITY PRESS Cambridge,New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi, Tokyo, Mexico City Cambridge University Press 32 Avenue of the Americas, New York, NY 10013-2473, USA www.cambridge.org Information on this title: www.cambridge.org/9780521116466 c Cambridge University Press 2011 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2011 Printed in the United States of America A catalog record for this publication is available from the British Library. Library of Congress Cataloging in Publication Data Raychaudhuri, Dipankar, 1955– Emerging Wireless Technologies and the Future Mobile Internet / Dipankar Raychaudhuri, Mario Gerla. p. cm. ISBN 978-0-521-11646-6 1. Wireless Internet. I. Gerla, Mario, 1943– II. Title. TK5103.4885.R39 2011 384.3–dc22 2010049729 ISBN 978-0-521-11646-6 Hardback Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party Internet Web sites referred to in this publication and does not guarantee that any content on such Web sites is, or will remain, accurate or appropriate.
- 11. CONTENTS Contributors ix Foreword byHisashi Kobayashi xi Acknowledgments xiii 1 Introduction 1 Dipankar Raychaudhuri and Mario Gerla 1.1 Background 1 1.2 Wireless Technology Roadmap 2 1.3 Wireless Networking Scenarios 4 1.4 Classifying Wireless Networking Scenarios 10 1.5 Future Network Requirements 14 1.6 Discussion 17 References 18 2 Next-Generation Wireless Standards and Their Integration with the Internet 19 Hang Liu 2.1 Technology and Service Trends of Emerging Wireless Standards 20 2.2 Radio Technologies in Next-Generation Wireless Standards 22 2.3 Spectrum Management and Cognitive Radio Networks 27 2.4 All IP Mobile Networks 29 2.5 Mobility and Vertical Handover 34 2.6 Multihop Wireless Networks 40 2.7 Concluding Remarks 51 References 51 v
- 12. vi Contents 3 AdHoc and Mesh Network Protocols and Their Integration with the Internet 54 Suli Zhao and Shweta Jain 3.1 Introduction and Motivation 54 3.2 Network Architecture 55 3.3 Protocol Design 58 3.4 Cross-Layer Adaptive Mechanisms 75 3.5 Integration with the Internet 84 3.6 Conclusion 86 References 86 4 Opportunistic Delivery Services and Delay-Tolerant Networks 92 Sanjoy Paul 4.1 Introduction 92 4.2 Design Principles 94 4.3 Alternative Architectures 96 4.4 Converged Architecture 108 4.5 Concluding Remarks 122 References 122 5 Sensor Networks Architectures and Protocols 125 Omprakash Gnawali and Matt Welsh 5.1 Introduction 125 5.2 Link Layer Protocols 126 5.3 Tree-Based Routing 132 5.4 Dissemination 135 5.5 Reliable Transport 139 5.6 Support Protocols 142 5.7 Cross-Layer Concerns 145 5.8 The Emergence of IP 147 5.9 Sensor Networks and the Future Internet 148 5.10 Conclusions 150 References 151 6 Network Services for Mobile Participatory Sensing 154 Sasank Reddy, Deborah Estrin, and Mani Srivastava 6.1 Mobile Participatory Sensing Vision 154 6.2 Context Inference and Coordination 158 6.3 Data Attestation and Credibility 166
- 13. Contents vii 6.4 Privacy169 6.5 Implications for the Future Internet 173 6.6 Conclusions 174 6.7 Acknowledgments 174 References 174 7 Supporting Cognitive Radio Network Protocols on Software-Defined Radios 178 George Nychis, Srinivasan Seshan, and Peter Steenkiste 7.1 Introduction 178 7.2 Software-Defined Radio Architecture and Challenges 180 7.3 Core Cognitive Radio and MAC Functions 183 7.4 Split Functionality Architecture 185 7.5 Evaluating the Split-Functionality Approach for Cognitive Radio Networks 187 7.6 MAC-Layer Evaluation 194 7.7 Related Work 198 7.8 Conclusions 199 References 200 8 Vehicular Networks: Applications, Protocols, and Testbeds 201 Mario Gerla and Marco Gruteser 8.1 Introduction 202 8.2 Vehicular Network and Application 204 8.3 Enabling Protocols 216 8.4 The Role of the Infrastructure: MobiMESH and GLS 225 8.5 Vehicular Testbeds 229 8.6 Conclusions 237 References 238 9 Opening Up the Last Frontiers for Securing the Future Wireless Internet 242 Wade Trappe, Arati Baliga, and Radha Poovendran 9.1 Security Challenges Facing the Future Wireless Internet 243 9.2 The Final Frontier: Introducing the Physical into Security 244 9.3 Platform and Device-Level Assurance 246 9.4 Location as an Enabler for Security Services 253 9.5 Using the Physical Layer to Enhance Security 272 9.6 Concluding Remarks 278 References 279
- 14. viii Contents 10 ExperimentalSystems for Next-Generation Wireless Networking 283 Sachin Ganu, Max Ott, and Ivan Seskar 10.1 Introduction 283 10.2 Future Wireless Networking Testbeds: Requirements and Challenges 286 10.3 Existing Wireless Testbeds 291 10.4 Global Environment for Network Innovations (GENI) 300 10.5 Concluding Remarks 308 References 309 11 Concluding Remarks 312 Dipankar Raychaudhuri and Mario Gerla
- 15. CONTRIBUTORS Arati Baliga SecurityR D Laboratory Deborah Estrin Department of Computer Science, UCLA Sachin Ganu Aruba Networks Mario Gerla Department of Computer Science, UCLA Omprakash Gnawali Department of Computer Science, Stanford University Marco Gruteser WINLAB, Rutgers University Shweta Jain York College, City University of New York Hisashi Kobayashi Princeton University Hang Liu InterDigital George Nychis Department of Electrical Computer Engineering, Carnegie Mellon University Max Ott NICTA (National Information and Communications Technology Australia) Sanjoy Paul InfoSys Technologies Limited Radha Poovendran College of Engineering, University of Washington Dipankar Raychaudhuri WINLAB, Rutgers University Sasank Reddy Department of Computer Science, UCLA Srinivasan Seshan School of Computer Science, Carnegie Mellon University Ivan Seskar WINLAB, Rutgers University Mani Srivastava Department of Computer Science, UCLA Peter Steenkiste Departments of Computer Science and Electrical Computer Engineering, Carnegie Mellon University Wade Trappe WINLAB, Rutgers University Matt Welsh School of Engineering and Applied Sciences, Harvard University Suli Zhao Qualcomm ix
- 17. FOREWORD The current Internetis an outgrowth of the ARPANET (Advanced Research Projects Agency Network) that was initiated four decades ago. The TCP/IP (Transmission Control Protocol/Internet Protocol) designed by Vinton Cerf and Robert Kahn in 1973 did not anticipate, quite understandably, such extensive use of wireless channels and mobile terminals as we are witnessing today. The packet-switching technology for the ARPANET was not intended to support real-time applications that are sensitive to delay jitter. Furthermore, the TCP/IP designers assumed that its end users – researchers at national laboratories and universities in the United States, who would exchange their programs, data, and email – would be trustworthy; thus, security was not their concern, although reliability was one of the key considerations in the design and operation of the network. It is amazing, therefore, that given the age of the TCP/IP, the Internet has successfully continued to grow by supporting the ever increasing numbers of end users and new applications, with a series of ad hoc modifications and extensions made to the original protocol. In recent years, however, many in the Internet research community began to wonder how long they could continue to do “patch work” to accommodate new applications and their requirements. New research initiatives have been launched within the past several years, aimed at a grand design of “a future Internet.” Such efforts include the NSF’s FIND (Future Internet Design) and GENI (Global Environment for Network Innovations), the European Community’s FP 7 (Frame-network Program, Year 7), Germany’s G-Lab, and Japan’s NWGN (New Generation Network). It is therefore extremely timely that Drs. Raychaudhuri and Gerla are publish- ing this book at this juncture, because better understanding of rapidly evolving wireless technologies and emerging new applications will be crucial in deciding the right architecture for the future Internet. It is not clear at this point which approach among several alternatives proposed or being pursued – ranging from xi
- 18. xii Foreword so-called clean-slatearchitectures to continuous enhancements of the current IP network – will eventually prevail, but there is no question that the future Internet architecture must be built with wireless technologies as its major components, and mobility of end users/terminals and security of applications and services must be adequately supported. The conventional architecture of treating a wireless network as an L-2 level access network connected to the core network (i.e., L-3 layer) through a gateway is becoming outdated. As pervasive computing in smart devices and wireless sensors/actuators attached to numerous things are expected to become predom- inant end users/devices in a future network, a novel network architecture and protocols with end-to-end control and routing, including heterogeneous wire- less subnetworks as an integrated part of the entire network, will be called for to provide mobility services with satisfactory performance, security, and scalabil- ity. Up to now, wireless technologies have been largely treated as synonymous with wireless communication links, where a wireless channel serves merely as an interface between the end mobile user and the core network. In the future network, however, we anticipate that in-network computing (or processing) of data from sensors and storing (or caching) of data based on its content ought to be performed. The introductory chapter of this book presents a variety of emerging wireless networking scenarios and identifies requirements for a new architecture and protocol for each of the mobile networking scenarios. These requirements are then aggregated into a number of key protocol features. Technical issues asso- ciated with implementing these wireless/mobility requirements into a unified comprehensive future Internet architecture protocol are then discussed. In the concluding chapter, Drs. Raychaudhuri and Gerla review the overall challenge of evolving the current Internet to meet these mobile networking needs and provide a roadmap for the future. Hisashi Kobayashi The Sherman Fairchild University Professor Emeritus, Princeton University, Princeton, New Jersey
- 19. ACKNOWLEDGMENTS The editors ofthis book gratefully acknowledge support from the National Science Foundation (NSF) in the form of a planning grant entitled “Planning Grant: New Architectures and Disruptive Technologies for the Future Internet – A Wireless Mobile Network Community Perspective,” CNS-0536545, 2005– 07. This grant provided the seed funding for a series of future mobile Internet workshops that led to the publication of the “Wireless Mobile Planning Group (WMPG)” report that motivated this book. We wish to thank our NSF program officer at the time, Dr. Guru Parulkar, for providing the original vision and inspiration behind the future Internet research program in the United States. We are also grateful to Darleen Fisher, Jie Wu, Ty Znati, and Suzanne Iacono of NSF CISE (Computer and Information Science and Engineering) and Chip Elliott of BBN Technologies for ongoing technical discussions, support for community workshops, and guidance of future Internet research under the FIND and GENI programs. Dr. Raychaudhuri would like to acknowledge sabbatical leave support from his home institution, Rutgers University, during the academic year 2008–2009, when much of this book was planned and organized. Thanks are also due to the Clean Slate Program at Stanford University (led by Prof. Nick McKeown) for providing him with office space and other resources during his sabbatical visit in 2008. Finally, he would like to express his gratitude to his wife, Arundhati Raychaudhuri, for her encouragement and support throughout the course of this project. Dr. Gerla would like to acknowledge the support of the NSF grant “The Health Guardian – A Gateway to Networked Wellness” and of the NSF-GENI grant “Campus Vehicular Testbed” that helped him focus on mobile and vehicular communications. Also, the International Technical Alliance project (led by IBM) supported some of the time dedicated to the research that went into this book. Finally, Dr. Gerla wishes to express his gratitude to his doctoral student, Eun Kyu Lee, for his outstanding editorial work during the final and very critical phase of integrating all the chapters to a consistent manuscript. xiii
- 21. 1 Introduction Dipankar Raychaudhuri andMario Gerla 1.1 Background Over the next ten-to-fifteen years, it is anticipated that significant qualitative changes to the Internet will be driven by the rapid proliferation of mobile and wireless computing devices. Wireless devices on the Internet will include laptop computers, personal digital assistants, cell phones (more than 3.5 billion in use as of 2009 and growing!), portable media players, and so on, along with embedded sensors used to sense and control real-world objects and events (see Figure 1.1). As mobile computing devices and wireless sensors are deployed in large num- bers, the Internet will increasingly serve as the interface between people moving around and the physical world that surrounds them. Emerging capabilities for opportunistic collaboration with other people nearby or for interacting with physical-world objects and machines via the Internet will result in new applica- tions that will influence the way people live and work. The potential impact of the future wireless Internet is very significant because the network combines the power of cloud computation, search engines, and databases in the background with the immediacy of information from mobile users and sensors in the fore- ground. The data flows and interactions between mobile users, sensors, and their computing support infrastructure are clearly very different from that of today’s popular applications such as email, instant messaging, or the World Wide Web. As a result, one of the broad architectural challenges facing the network research community is that of evolving or redesigning the Internet architec- ture to incorporate emerging wireless technologies – efficiently, and at scale.1 The Internet’s current TCP/IP protocol architecture was designed for static hosts and routers connected by wired links. Protocol extensions such as mobile IP have been useful for first-generation cellular mobile services involving single-hop radio links from mobile devices to base stations or access points.2 However, incremental solutions based on IP are inadequate for dealing with the 1
- 22. 2 Introduction INTERNET ~2010 ~2020 ~1B servers/PC’s,10B notebooks, PDA’s, cell phones, sensors ~700M server/PC’s, ~300M laptops/PDA’s Wireless Edge Network Wireless Edge Network Future INTERNET (converged with cellular) Figure 1.1. Migration of Internet usage from fixed PCs and servers to mobile devices and sensors. requirements of fast-growing wireless usage scenarios such as multihop mesh,3 peer-to-peer,4 disruption-tolerant networks (DTN),5 sensor systems,6 and vehic- ular applications.7 These emerging wireless scenarios motivate us to consider “clean-slate” network architectures and protocols capable of meeting the needs of these and other emerging wireless scenarios. In the next section (1.2), we present an overview of these emerging wireless networking scenarios, identify- ing new architecture and protocol requirements for each of these usage cases. These mobile network architecture requirements will then be aggregated into a number of key protocol features in Section 1.3 that follows. Technical chal- lenges associated with implementing these new wireless/mobility requirements into a unified comprehensive future Internet architecture protocol will then be discussed briefly in Section 1.4. Each of the emerging wireless technology sce- narios identified in this introductory chapter will then be discussed in greater depth in each of the chapters that follows. In the concluding chapter, we will review the overall challenge of evolving the current Internet to meet these mobile networking needs, and provide a brief view of the road ahead. 1.2 Wireless Technology Roadmap Wireless and mobile networks represent an active research and new technology development area. The rapid evolution of core radio technologies, wireless networks/protocols, and application scenarios is summarized for reference in the technology roadmap given in Figure 1.2. It can be seen from the chart that in addition to 2.5G/3G cellular data and WLAN systems developed during the 1990s, emerging wireless scenarios include personal-area networks, wireless peer-to-peer (P2P), ad hoc mesh networks, cognitive radio networks, sensor networks, RFID systems, and pervasive computing. Each of the previously mentioned wireless technologies or usage scenarios is associated with unique network architecture and service requirements that
- 23. Plateforms Figure 1.2. Wirelesstechnology roadmap. 3
- 24. 4 Introduction affect boththe access and infrastructure portions. The default approach adopted by most of the research community is to treat the wireless access portion as a “layer 2” local area network connecting to the Internet (i.e., layer 3 IP) through a gateway. This approach is pragmatic, but it precludes uniform dissemination of control and routing information through the entire network and creates a poten- tial processing bottleneck at the gateway. A more integrated end-to-end control and routing architecture is important for optimizing mobile/wireless service fea- tures such as location management, dynamic handoff, quality-of-service (QoS) or cross-layer transport. Also, a local-area wireless network may contain one or more routing elements, which can create inconsistencies in protocol layering and addressing. If compatibility with the current IP network is not viewed as an essential constraint, it may be possible to develop a clean-slate network archi- tecture that can accommodate emerging wireless networks in a single unified protocol structure. 1.3 Wireless Networking Scenarios The most important wireless technology in use today is the cellular network that provides mobile phone and data services on handheld devices. Cellular networks are ubiquitous in all parts of the world, with almost 4 billion cell phones in use worldwide at the time of writing of this book. Cellular networks have evolved from first-generation analog systems (such as the AMPS system used in the United States prior to 1990) to second-generation digital systems (such as GSM and CDMA8 used in most parts of the world between 1990 and 2005), and then to third-generation, or 3G, systems such as CDMA2000 and UMTS/WCDMA in use since about 2005. Second-generation cellular systems such as GSM are capable of supporting packet data services at bit-rates of ∼100 Kbps, whereas 3G systems such as UMTS or CDMA2000 can deliver between ∼300 Kbps – 2 Mbps, depending on signal quality. Further evolution from 3G to 4G cellular systems with the goal of supporting service bit-rates in the range of ∼10–100 Mbps is planned by the industry over the next three to five years. Examples of 4G systems are LTE and WiMAX/IEEE 802.16. From a network architecture point of view, cellular has always been built as a separate custom network with its own set of protocols for key interfaces, such as mobile terminal to base station and base station to mobility service gateways such as the MSC and GGSN. These networks were initially built for integration with the telephone network that was based on a set of signaling protocols defined by the ITU. More recently, 3G networks have been migrating toward integration with the IP network using voice-over-IP (VoIP) protocols such as SIP9 for signaling and mobility protocols such as mobile IPv6.2 As data ser- vices for mobile devices continue to grow, this may be expected to lead to a gradual migration of mainstream cellular services to the Internet. However, grad- ual migration of cellular networks to the Internet involves the use of overlays
- 25. 1.3 Wireless NetworkingScenarios 5 and gateways for interfacing between mobile network features such as authen- tication, addressing, and mobility – an approach that has scalability and perfor- mance limitations. In addition to cellular, a number of short-range wireless data technologies such as WiFi, Bluetooth, and Zigbee have started to penetrate the market for enterprise and home networks starting in the late 1990s. Of these technologies, WiFi (based on the IEEE 802.11 standard) is the most ubiquitous as an Internet access link, with more than 500 million devices in use today, with the number expected to grow to a billion by 2012. Most of these WiFi devices are used as wireless local area networks (WLAN) that connect to the Internet as “layer 2” networks similar to the widely used Ethernet LANs. When WiFi is used as a home or office LAN, it is the last hop for Internet access, but does not provide mobility or global roaming features associated with the cellular network. As we will see in later chapters, 802.11 WLAN technology is also being used in the ad hoc mode to build new kinds of networks such as peer-to-peer (P2P), vehicular networks (V2V and V2I), and mesh networks. In addition to 802.11 radios, there are several short-range radio standards such as Bluetooth and Zigbee that are used to provide short-range access to devices such as wireless speakers and sensors/actuators. Power and size limitations on the sensor devices imply the need for a more general wireless network architecture that provides connectivity to a range of heterogeneous radios with different transmission ranges. In contrast to the cellular network, the emerging wireless network will incorporate multiple radio technologies operating under a decentralized control framework. This is illustrated in Figure 1.3, which shows that the overall network architec- ture is evolving from the separate special-purpose cellular and WiFi networks toward a more general, heterogeneous wireless access network with multiple radio technologies, opportunistic ad hoc association, self-organization, multihop routing, and so on. The long-term architectural goal would be to evolve the Inter- net architecture to seamlessly meet all the requirements associated with the gen- eral wireless “network of networks” shown in the right-hand side of the figure. Next, let us consider some of the key wireless networking scenarios of impor- tance to the future Internet architecture. The first and most well-understood emerging wireless service scenario is that of anytime, anywhere access to the Internet from personal mobile devices. As shown in Figure 1.4, this scenario implies the need for a network addressing and routing scheme capable of han- dling roaming and continuous mobility across multiple points of attachment. User mobility of this sort is handled quite effectively in today’s cellular network using the concepts of a “home network” and “visited network.” In particular, users of the network have a permanent address to which all com- munication is initially addressed, and a forwarding (or visiting) address used to temporarily forward connections during mobility outside the home area. A modified form of this approach has been used in the mobile IP specification
- 26. 6 Introduction Figure 1.3.Anticipated evolution of wireless network architecture from special-purpose networks to heterogeneous “wireless network of networks.” that is part of IPv6, but is not widely implemented in the Internet today. For connection-oriented traffic, an additional requirement that is also met by today’s cellular networks is that of dynamic handoff by which an existing connection can be smoothly migrated from one point of radio attachment to another without setting up a new connection. Clearly, end-user roaming and dynamic mobility support is a key requirement for the future Internet given the rapid increase in mobile data devices. Although mobile IPv6 does provide a solution for this requirement, it may be appropriate to consider alternative approaches toward achieving this functionality in the future network. Mobility also involves security Figure 1.4. Mobile data service scenario.
- 27. 1.3 Wireless NetworkingScenarios 7 Figure 1.5. Wireless mesh network with multihop routing of data packets between radio nodes. considerations such as user authentication, which will need to be an integral part of any solution. A second emerging wireless usage scenario is that of an ad hoc or mesh network in which multiple wireless devices with short-range radios form a multihop network with increased coverage and connectivity. Ad hoc networks were first proposed to support tactical communications between small groups of mobile radio nodes. More recently, multihop mesh architectures (illustrated in Figure 1.5) have been used to extend wireless access network coverage in both urban and rural areas using low-cost short-range radios such as WiFi. In these ad hoc and mesh scenarios, each radio node serves as a router with the capability of forwarding packets to their destination across multiple wireless hops. Traffic to or from the Internet must pass through one or more gateways or access points that are designed to have both wired and wireless network interfaces. Specialized ad hoc network routing protocols (such as the MANET specification from IETF10 ) have been devised for this purpose, and there is a considerable body of research on this class of routing protocols. Routing in mesh and ad hoc networks generally requires an awareness of cross-layer parameters from the radio links that make up a potential path. Given the growing importance of multihop wireless routing, it may be useful for the future Internet protocol to provide seamless routing across both wired and wireless portions of the network. As for the mobile data service scenario in Figure 1.3, the network needs to support end-user roaming and dynamic mobility as part of the basic transport service.
- 28. 8 Introduction Figure 1.6.P2P wireless networking scenarios involving sensor pickup by a mobile device, or opportunistic content delivery to a passing vehicle. The third scenario of current significance is the P2P network model in which short-range radios associate with each other opportunistically for content deliv- ery or some type of machine-to-machine (M2M) interaction. This scenario is also sometimes referred to as delay-tolerant networking (DTN), because intermit- tent opportunistic connectivity implies the need for delay-tolerant applications designed to wait for transmit/receive opportunities. Figure 1.6 shows two kinds of P2P or DTN applications, one in which a bus is picking up data from sensors in the roadway and storing this data for later delivery to the wired network core (perhaps using WiFi or other short-range radios once parked inside its regular garage). The second part of the figure shows the P2P and “Infostations” service models in which users associate opportunistically with each other to exchange content, or when users associate for short periods with wireless data caches (or Infostation) to download popular or personal content. Both these scenarios are important because of the fact that opportunistic short-range radio access is fun- damentally faster and more efficient than continuous cellular-type connectivity. Moreover, continuous long-range wireless access may not be feasible for small, low-power sensor devices such as those shown in Figure 1.6. It is noted that the TCP/IP protocol stack used in the Internet today was not designed to support discontinuous or opportunistic connectivity of this type, indicating the need to consider this requirement further when designing future Internet protocols. Another emerging wireless scenario of importance is that of vehicular networking, involving both V2V (vehicle-to-vehicle) and V2I (vehicle-to- infrastructure) modes. In vehicular networking, cars on the highway may ex- change safety information with those in proximity, or might download content (such as navigational maps or audio/video files) from infrastructure access points placed along the highway. The vehicular scenario shares some common elements with the ad hoc and P2P cases considered earlier, but have the additional property of location or geographic awareness. Referring to Figure 1.7, it is observed that
- 29. 1.3 Wireless NetworkingScenarios 9 Figure 1.7. Vehicular networking scenario (figure courtesy of Prof. Marco Gruteser). a typical transmission in a V2V situation is a “geographic multicast” in which a message is propagated to all receivers along a certain section of roadway, but not to those outside that region. This requirement motivates a new service, called geocasting, in which a message is forwarded to all radio nodes within a defined geographic area. This type of network routing is very different from device- address-based routing currently used in the Internet. Given the fact that there are approximately 500 million vehicles worldwide and growing, it would be desirable to consider this geographic routing capability as a requirement when designing future Internet protocols. Another important wireless scenario is that of sensor networks and pervasive computing (see Figure 1.8). The sensor network scenario generally involves a hierarchical network structure with clusters of low-power sensors connected as Figure 1.8. Wireless sensor network scenario.
- 30. 10 Introduction ad hocmultihop networks at the lowest tier. The function of a sensor (or actuator) is to provide a virtualized representation of a physical-world object or event, thus making it possible to design “pervasive computing” applications that allow us to observe and interact with the physical world. The sensor network clusters connect into the Internet cloud through multiple gateways that convert from the localized sensor network protocol to the global Internet protocol. Within the sensor network cluster, there may also be a tiering of nodes includ- ing low-power sensors, relays, forwarding nodes, and gateways. Of course, ad hoc routing considerations similar to those discussed earlier for the ad hoc/mesh case continue to apply. However, there is an additional requirement of energy efficiency because of severe power constraints at each sensor, and there may also be unique data aggregation requirements involving processing and aggregation of data at each transit node. Sensor network applications involve computing and storage servers in the network cloud as shown in Figure 1.8, and there are many related issues of how to architect the computing and networking system given the greater importance of content and location over the physical address itself. Applications will also have an end-user interface, typically a mobile device such as a cellular handset or PDA. Currently sensor systems are built as special-purpose networks with gateways to the Internet, but a long-term goal is to improve scalability and performance by using a single unified protocol across both sensor and Internet clouds. In concluding this subsection, it is noted that core radio technology itself is going through a fundamental change, moving from hardware radios to cogni- tive software-defined radios. Examples of early cognitive radio prototypes are the USRP (Universal Software Radio Prototype), WARP from Rice University, the Microsoft Research Software Radio, and the WINLAB WiNC2R software radio platform. Cognitive radios are motivated by the need to use radio spectrum more efficiently to accommodate rapidly increasing wireless traffic. The use of cognitive radios as network elements will enable dynamic spectrum sharing and adaptive networking methods that are inherently more flexible than the radio access technology standards in use today. This implies the need for extensions to control and resource management protocols in the access network, provid- ing for features such as dynamic spectrum coordination, cross-layer aware- ness, and the ability to set and control radio parameters based on networking requirements. 1.4 Classifying Wireless Networking Scenarios The NSF Wireless Mobile Planning Group report1 written in 2005 provides a useful classification for the full range of future wireless networking scenarios, some of which were individually discussed earlier, in Section 1.3. In that report, three distinct clusters of usage scenarios are identified as summarized below.
- 31. 1.4 Classifying WirelessNetworking Scenarios 11 1.4.1 Scenario A – Individual Wireless Devices Interfacing with the Internet (“Mobile Computing”) The simplest scenario involves a single wireless device that interfaces with the broader Internet. The mobile device may be a cellular phone, a PDA, a media player, a digital camera, or some type of combination consumer device. Mobile computing devices may connect through a wireless local area network, a mesh- style wireless network, or a wide-area wireless technology (such as cellular 3G or WiMAX). Service models to be considered include mobile services, hot-spot services with limited mobility, as well as cached content delivery via oppor- tunistic wireless links. High mobility, the potential for intermittent connectivity, and heterogeneity of radio access are key characteristics of this scenario. A typical example of this mode of operation is that of a mobile customer downloading a real-time video stream (e.g., a live sporting event) to a portable media player from the Internet. Seamless connectivity should be maintained as the customer moves from a shopping mall (WiFi coverage) to outdoors (2.5G or 3G cellular connectivity), and then to the car (Bluetooth within the car, WiMAX radio to the Internet). At each step, the wireless media player needs to be aware of available connectivity options and then select the best service. The multimedia server must also be aware of current connectivity constraints so that it can deliver a stream with parameters (data rate, format, etc.) consistent with the configuration. The same mobile customer should be efficiently tracked by the network and reachable by VoIP calls if he/she so chooses. Location- or context- aware queries (such as “where is the nearest pharmacy?”) and delay-tolerant services (e.g., seamless suspension and resumption of a large file transfer when the user walks or drives through areas without coverage) should be supported. Caching of files for rapid downloading within a hot spot may also be useful in this scenario. 1.4.2 Scenario B – Constellations of Wireless Devices (“Ad hoc Nets”) The second type of wireless scenario is motivated by a variety of settings in which multiple radio devices may be in close physical proximity and can collaborate by forming an ad hoc network. For example, wireless devices in an office or home environment can set up an ad hoc network between themselves to improve coverage and communications quality. Another popular application involving constellations is that of community mesh networks formed by rooftop radios for the purpose of shared broadband access. In the important emerging application of vehicular communication, clusters of cars on the highway may participate in an ad hoc network for the purpose of collision avoidance and traffic flow management. Constellations may include heterogeneous radio and computing devices with different capabilities and resource levels. Emerging cognitive radio
- 32. 12 Introduction technologies alsooffer the capability of highly adaptive wireless ad hoc networks with physical layer negotiation between nodes, scavenging unused spectrum at low cost to support a private ad hoc network. Opportunistic association, changing network topologies, varying link quality, and potentially large scale (in terms of number of nodes) are some of the characteristics of this scenario. A simple example of opportunistic constellations is the formation of an ad hoc network between several user laptops in a meeting room with limited Internet access coverage. The ad hoc network enables high bandwidth communication between participants at the meeting and allows them to use a favorably positioned (e.g., with good cellular network throughput) node as a forwarding relay to the Internet. Another example is the cooperative downloading of popular files from the Internet by drivers on a highway, when hot-spot “Infostations” with WiFi service are spaced by several miles on the highway, and a car traveling at 60 miles per hour may not be able to download an entire file through short V2I (vehicle-to-infrastructure) mode access. If several drivers are interested in the same file, it is possible for the cars to collaborate and exchange segments in a P2P opportunistic networking arrangement similar to that used in Bit Torrent (see Chapter 7). This allows the download to be completed without requiring a car to stop at a hot spot, saving time for the end-user and avoiding traffic congestion problems. The same ad hoc networking capability can also be used by cars to exchange control information necessary for traffic flow management or collision avoidance. Ad hoc radio constellations also apply to civilian disaster recovery and in tac- tical defense environments. These applications usually involve communications between a number of first responders or soldiers who work within close proxim- ity of each other. The response team may need to exchange text messages, stream- ing media (e.g., voice or video), and use collaborative computing to address a shared task such as target recognition or identification of a spectral jammer. Individual nodes may also need to access the Internet for command-and-control purposes or for information retrieval. This application has similarities with the ad hoc mesh network for suburban or rural broadband access mentioned earlier. 1.4.3 Scenario C – Pervasive Systems and Sensor Networks (“Sensor Nets”) Sensor netsrefer toa broadclassof systemsinvolvingembeddedwirelessdevices connected to the Internet. The first generation of sensor networks involves col- lecting and aggregating measured data from large numbers of sensors in a specified geographic area. In the near future, sensor net applications will also include closed-loop sensor/actuator systems for real-time control of physical world objects. Current sensor net applications are in science (ecology, seis- mology, ocean and atmospheric studies, etc.) and engineering (water quality
- 33. 1.4 Classifying WirelessNetworking Scenarios 13 monitoring, precision agriculture, livestock tracking, structural monitoring), as well as consumer-oriented applications (home security and energy management, hobbyist and sports enthusiast applications of distributed imaging, eldercare, pet monitoring, etc.). Sensor networks share several characteristics of ad hoc scenar- ios but are differentiated by the fact that tiny sensor devices have more stringent processing power, memory, and energy constraints. These constraints generally imply the need for a hierarchical ad hoc network structure in which low-tier sensor nodes connect to the Internet via one or more levels of repeating wireless gateways. Other important characteristics of this scenario are the data-centric nature of applications, potential for large scale (in terms of numbers of sensors), and geographic locality. Traditionally, large “sensor fabrics” such as those installed to monitor the environment have been designed as vertically optimized systems, with an ad hoc network designed to meet specific energy and processing constraints and optimized to support specialized queries dictated by the application at hand. The interface to the Internet has been via edge nodes that isolate the Internet stack from the sensor fabric architecture. However, more recent trends indicate an increased need for sensor networks that provide open access via the Internet, in a more extensive and capillary way that can be supported via edge nodes. For instance, scientists interested in the correlation between data found in dif- ferent data bases (e.g., soil characteristics, pollutants carried in the local water supplies, productivity of local vineyards, production and sale of local wines) can be permitted to access specific regions within a sensor fabric directly from the Internet to extract the required data rather than overburdening the access gateways. Moreover, new types of sensor networks based on “mobile” sensor platforms are becoming available – for example, vehicles in the urban grid or firefighters in a disaster recovery operation equipped with a variety of sensors (video, chemical, radiation, acoustic, etc.). These sensor platforms have practi- cally unlimited storage, energy, and processing resources. The vehicle grid then becomes a sensor network that can be accessed from the Internet to monitor vehicle traffic congestion and to help investigate accidents, chemical spills, and possible terrorist attacks. Likewise, firefighters carry cameras and several other sensors, allowing the commander to be aware of the conditions in the field and to direct the operations to maximize the use of the forces while preserving the life of his responders. These latter examples also show that the gap between sensor networks and ad hoc networks tends to diminish in mobile sensor sys- tems at least in terms of communications capabilities and Internet access. In the longer term, pervasive systems involving personal mobile devices, smart offices/homes, and densely deployed multimodal sensors/actuators will serve as a platform for development of various new applications ranging from track- ing and inventory control to personal productivity, public safety, and resource management.
- 34. 14 Introduction 1.5 FutureNetwork Requirements Before moving to more detailed discussions of future wireless scenarios and their networking protocols in the following chapters, let us briefly consider the general future network design requirements that arise from the scenarios introduced in this chapter. Considering the wide range of future wireless network usage scenarios (4G cellular/mobile, WLAN, mesh, P2P, DTN, sensor networks, vehicular networks, sensor/pervasive systems), it is important to extract a set of common require- ments general enough to meet these needs, as well as those of future applications that cannot easily be predicted today. We suggest an approach for decomposing these requirements into two major categories, the first reflecting the intrinsic properties of the radio medium and the second reflecting the needs of future mobility and pervasive services. It is important to note that these requirements should apply to future access networks and the Internet protocol stack as a whole in view of the increasingly predominant role of wireless end-user devices. The current approach of designing specialized networking solutions for cellular systems, ad hoc nets, sensor applications, and so on leads to undesirable frag- mentation (and hence poor scalability, lack of interoperability, inefficiencies in application development, etc.) among different parts of the network, and needs to be replaced by a unified end-to-end protocol architecture that supports emerging requirements of both wired and wireless networks. To elaborate further, basic transport services of future Internet protocols should reflect intrinsic radio properties such as spectrum use, mobility, vary- ing link quality, heterogeneous PHY, diversity/MIMO, multihop, multicast, and so on, and the capabilities of emerging radio technologies such as LTE, next- generation WLAN, Bluetooth, Zigbee, vehicular standards such as 802.11p, and of course, cognitive software-defined radio (SDR). In addition, Internet protocol service capabilities should be designed to serve emerging uses of wireless tech- nology, not only for conventional mobile communications, but also for content delivery, cloud computing, sensing, M2M control, and various other pervasive system applications. Here, we briefly identify some of the key requirements for a future network designed to support the range of wireless usage scenarios discussed in Sec- tions 1.3 and 1.4. Of course, it might not be feasible to achieve the full set of requirements in a single networking architecture, but it is still instructive to understand all the needs in a top-down manner before considering implementa- tion issues. Examples of specific mobile network protocol features that may be useful are: 1. Dynamic spectrum coordination capability: Historically, network protocols have been designed to support resource management in terms of wired network concepts such as link bandwidth and buffer storage. As radios
- 35. 1.5 Future NetworkRequirements 15 become an increasingly important part of the network, it will be useful to be able to specify and control radio resources within the networking protocol itself. For example, control protocols should be able to support dynamic assignment of spectrum to avoid conflicts between multiple radio devices within the network. Just as current IP networks incorporate protocols such as dynamic host control protocol (DHCP) for address assignment, future networks could incorporate a distributed repository of spectrum usage infor- mation that could then be used to assign nonconflicting spectrum to radio devices when they join the network. 2. Dynamic mobility for end-users and routers: As more and more end-user devices become wireless, networks will need to be designed to support mobility as a normal mode of operation rather than as a special case. This means that end-user devices should be able to attach to any point in the network (i.e., global roaming), with the network providing for fast authen- tication and address assignment at a very large scale. Currently available mechanisms such as DHCP and mobile IP represent a first in this direction, but a more general solution could involve a clean separation of naming and addressing where each device would have a unique name, but would only be assigned a routable address local to the network with which it is currently associated (and this routable address may be as general as a geographic location, i.e., geo-address). The main challenge is to provide a distributed global name resolution and address assignment service that scales to the level of billions of mobile devices. Because wireless devices may also serve as routers in some of the ad hoc environments discussed earlier, the network should be able to support dynamic migration of subnetworks. In addition, dynamic handoff of traffic from one point of attachment to another may be required for certain connection-oriented services. 3. Fast discovery and ad hoc routing: Because several wireless usage scenarios involve ad hoc associations and continuously changing network topology, it is important for the network to support fast discovery of neighboring network elements. Discovery protocols for ad hoc networks should sup- port efficient topology formation in multihop wireless environments taking into account both connectivity requirements and radio resources. Multihop wireless scenarios further require efficient ad hoc routing between network elements with dynamically changing topologies and radio link quality. The ad hoc routing protocol used in wireless access networks should seam- lessly integrate with the global routing protocol used for end-to-end con- nectivity. 4. Cross-layer protocol stack for adaptive networks: Routing in multihop wire- less networks requires a greater awareness of radio link layer parameters to achieve high network throughput and low delay. This means that the net- work’s control plane should include information about radio link parameters to be used for algorithms that support topology discovery and routing. A
- 36. 16 Introduction key architecturalissue is that of determining the appropriate granularity and degree of aggregation with which this cross-layer information is exchanged across different parts of the network (i.e., access, regional, core, etc.). 5. Incentive mechanisms for cooperation: Ad hoc mobile networking scenarios typically involve cooperation among independent wireless devices. It will be important for future Internet protocols to include protocols that enable such cooperation, first by advertising resources and capabilities to neighboring radios and second by providing mechanisms for exchange of credits or barter of resources in return for services such as relaying or multihop forwarding. 6. Routing protocols for intermittent disconnection: Today’s Internet routing and transport protocols are designed under the assumption of continuous connectivity. However, this assumption is no longer valid for mobile devices that frequently experience disconnection due to radio signal fading and/or service unavailability. Future protocols should be designed for robustness in presence of occasional disconnection. In order to achieve this, the network generally needs to be able to store in-transit data during periods of disrup- tion, while forwarding messages opportunistically when a path becomes available. 7. Transport protocols for time-varying link quality: Reliable delivery of data on the Internet is currently accomplished using transport control protocol (TCP) for end-to-end flow control and error control. TCP is known to per- form poorly in wireless access networks that are characterized by higher packet error rates than wired links, along with time-varying bandwidth caused by variations in radio channel quality and medium access control (MAC) layer contention. Future transport layer protocols should be designed to work efficiently in presence of packet errors and varying end-to-end bandwidth – this will require the ability to distinguish between congestion in the network and channel quality variations. 8. Efficient multicasting and multipath routing: The wireless channel has inher- ent multicast capabilities, that is, a single packet sent by a radio is simultane- ously received by all receivers within the transmission range. This property can be exploited to improve network performance in various scenarios, but the routing and transport protocols have to be enhanced to support multicast operation as a core capability. Radio multicast also opens up the possibil- ity of multipath routing in which multiple independent paths are used for routing a single packet to improve end-to-end reliability and delay. 9. Location awareness and geographic routing: As discussed earlier, emerg- ing pervasive computing applications (i.e., vehicular, sensor, M2M) often require the ability to delivery packets to an entire geographic region rather than to a specific IP address. Also, for mobility services, knowledge of the current geographic location is central to providing various new services such as navigation and geographic search. This means that future networks should provide location information as a basic control plane capability. In
- 37. 1.6 Discussion 17 addition,it would be desirable to optionally offer geographic multicast and routing modes by which packets can be delivered to a specified geographic region. 10. Content- and context-awareness: A number of future network service sce- narios involve content addressability or content routing. For example, an M2M application might involve a query for a particular functionality (such as “printer”), and it would thus be useful if the network protocol can resolve a content query to one or more specific network addresses. Another network capability to be considered is that of content routing by which network routers forward traffic based on content attributes of the data being carried in the packet rather than the IP address in the header. 11. In-network storage for content caching: A network with content address- ability capabilities can also be enhanced to provide in-network storage and caching services in an integrated manner. Caching of popular or personal content can provide significant improvements in both end-user application performance and network throughput. Although these capabilities can be provided above the network as an “overlay,” it is worth considering whether content caching should be fully integrated with the network layer protocol to minimize control overheads and delay. 12. Programming model for in-network processing: Emerging sensor and perva- sive applications may involve in-network computation for functions such as data aggregation, data-dependent routing or local content search. Whereas these functions are typically implemented above the networking layer as overlays, it is worth considering basic computing features for a future mobile network in which an increasing proportion of applications would benefit from in-network computation. A key issue is the design of a pro- gramming model by which to specify optional computational functions at each network element. 13. Enhanced security and privacy for radio medium: Because the wireless channel is open to eavesdroppers and potential denial-of-service attackers, it is important to consider enhanced security and privacy features for emerging mobile networks. User mobility implies the need for stronger authentication features as a baseline for any device joining the network, while the open radio medium means that transmissions should generally use strong encryption. In addition, if the network has information about location or content, it would be important to build in privacy guarantees that prevent tracking of users or their content. 1.6 Discussion In Section 1.5, we have used a top-down approach to identify a number of new network protocol capabilities that would be desirable for the future mobile Internet. Clearly, it is very difficult to incorporate all or most of these features
- 38. 18 Introduction into asingle network architecture even if we start from a so-called clean slate. Moreover, clean-slate design of an existing network as large and complex as the Internet is not really a practical option, and any practical attempt to upgrade functionality must eventually consider factors such as backward compatibility, evolutionary upgrade of equipment, equipment cost, software complexity, and so on. However, the top-down clean-slate design methodology described in this book is expected to be beneficial because it exposes key requirements and design issues without being constrained by current practices. Although a single new Internet protocol is unlikely to emerge from this methodology, it may be expected that researchers will design and validate several of the key network capabilities outlined in Section 1.5, and eventually some of these ideas will migrate into the mainstream Internet protocol. In the chapters that follow, we will explore the details of protocol design for each of the emerging wireless service scenarios outlined in this introductory chapter. In the concluding chapter, we will briefly discuss a roadmap to the future, including some strategies for how to put all these ideas together into a unified network architecture. References [1] Raychaudhuri, D. and Gerla, M. 2005. New Architectures and Disruptive Tech- nologies for the Future Internet: The Wireless, Mobile and Sensor Network Per- spective. Report of NSF Wireless Mobile Planning Group (WMPG) Workshop. http://www.winlab.rutgers.edu/WMPG [2] Perkins, C. 1998. Mobile IP. IEEE Communications Magazine, 35(5), 84–86, 91–99. [3] Akyildiz, I., Wang, X., and Wang, W. 2005. Wireless Mesh Networks: A Survey, Computer Networks. Computer Networks and ISDN Systems, March. [4] Lamming, M. and Bohm, D. 2003. SPECs: Another Approach to Human Context and Activity Sensing Research, Using Tiny Peer-to-Peer Wireless Computers. Lecture Notes in Computer Science, October. [5] Fall, K. 2003. A Delay Tolerant Network Architecture for Challenged Internets. ACM SigComm. [6] Culler, D., Estrin, D., and Srivastava, M. 2004. Guest Editors’ Introduction: Overview of Sensor Networks. IEEE Computer Magazine, August. [7] Zanella, A., Fasolo, E., Padova, C., Chiasserini, F., Meo, M., Torino, M., Frances- chinis, M., and Spirito, A. 2006. Inter-vehicular communication networks. Second Internal NEWCOM Workshop. [8] Rappaport, T. 2002. Wireless Communications: Principles and Practices. Second ed. Prentice Hall. [9] Rosenberg, J. et al. 2002. SIP: Session Initiation Protocol. Internet Engineering Task Force RFC 3261. [10] Perkins, C., and Belding-Royer, E. 2003. Ad hoc On-Demand Distance Vector (AODV) Routing. Internet Engineering Task Force, RFC 3561.
- 39. 2 Next-Generation Wireless Standards andTheir Integration with the Internet Hang Liu Abstract Standards provide the foundation for developing innovative technologies and enabling them to be widely adopted in market. Several major international stan- dard bodies are developing next-generation wireless standards, including the Institute of Electrical and Electronics Engineers (IEEE), the Internet Engineering Task Force (IETF), the International Telecommunication Union Radiocommu- nication Sector (ITU-R), the European Telecommunications Standards Institute (ETSI), and the Third Generation Partnership Project (3GPP). The standardiza- tion activities of IEEE 802 committee mainly focus on physical (PHY) and media access control (MAC) layers, that is, layers 1 and 2 of the network protocol stack, including WLAN, WMAN, and WPAN network interfaces. IETF standards deal with layer 3 and above, in particular with standards of the TCP/IP and Inter- net protocol suite, including mobile IP and mobile ad hoc networks (MANET) related protocols. ITU-R is one of the three sectors of the ITU and is responsible for radio communications. It plays a vital role in the global management of the radio-frequency spectrum and satellite orbits, and developing standards for radio communications systems to assure the necessary performance and quality and the effective use of the spectrum. ETSI is a European standards organization for producing globally applicable standards for information and communications technologies (ICT), including fixed, mobile, broadcast, and Internet technolo- gies. ETSI inspired the creation of, and is a partner of, 3GPP – a collaboration project between groups of telecommunications associations worldwide. 3GPP’s original scope was to produce technical specifications and technical reports for a globally applicable 3G cellular mobile system based on evolved Global System for Mobile communications (GSM) core networks and radio access technolo- gies, as well as maintain and develop GSM technical specifications and reports. It is currently developing 4G mobile network system. 3GPP standardization 19
- 40. 20 Next-Generation WirelessStandards and Their Integration with the Internet Figure 2.1. Major standards processes for next-generation wireless networks. encompasses radio access, core network, and service architecture. Figure 2.1 illustrates major standards processes for next-generation wireless networks in IEEE, 3GPP, and ITU-R. 2.1 Technology and Service Trends of Emerging Wireless Standards The standardization efforts for future wireless networks focus on both new radio access interfaces and improved network architectures. The standardization work on new radio interfaces aims at increasing network capacity to match or shorten the gap with wireline broadband access, and improving bandwidth efficiency and coverage range by employing advanced physical and MAC layer techniques such as multiple-input and multiple-output (MIMO), orthogonal frequency-division multiple access (OFDMA), and space-division multiple access (SDMA), as well as extending battery life and reducing latency for real-time communications. As shown in Table 2.1, future WLAN and WPAN standards will support up to 1 Gbps data rate, and future WMAN and cellular standards can support a peak
- 41. 2.1 Technology andService Trends of Emerging Wireless Standards 21 Table 2.1. Emerging Wireless Interfaces PHY MAC Operating Standard Maximum PHY Rate Technology Technology Frequency 802.11n WLAN 600 Mbps (4 × 4 MIMO, 4 spatial streams, 40 MHz bandwidth); 200 Mbps (3 × 3 MIMO, 3 spatial streams, 20 MHz bandwidth) MIMO and OFDM EDCA and HCCA 6 GHz, typical 2.4 GHz and 5 GHz 802.11ac WLAN 1 Gbps for multi-station; 500 Mbps for a single link MU-MIMO and OFDM SDMA 6 GHz, typical 2.4 GHz and 5 GHz 802.11ad WLAN 1 Gbps TBD TBD 60 GHz 802.15.3c high rate WPAN 5 Gbps on 2 GHz bandwidth Single carrier and OFDM TDMA and CSMA-CA 60 GHz 802.15.4/4a low rate WPAN 250 kbps with 802.15.4; 27 Mbps with 802.15.4a UWB PHY; 1 Mbps with 802.15.4a spread spectrum PHY Spread spectrum and UWB TDMA and CSMA-CA Spread spectrum PHY: typical 2.4 GHz, 915 MHz, 868 MHz; UWB PHY: 3 GHz to 5 GHz, 6 GHz to 10 GHz, and less than 1 GHz 802.16m WMAN 300 Mbps for downlink (4 × 4 MIMO, 20 MHz bandwidth); 135 Mbps for uplink (2 × 4 MIMO, 20 MHz bandwidth) MU-MIMO and OFDM OFDMA in downlink and uplink 6 GHz 3GPP LTE E-UTRAN 300 Mbps downlink (4 × 4 MIMO, 20 MHz bandwidth); 75 Mbps uplink for a user (SC-FDMA, 20 MHz bandwidth) MU-MIMO and OFDM OFDMA in downlink and SC-FDMA in uplink 6 GHz downlink rate of several hundred Mbps and a peak uplink rate of ∼100 Mbps under high mobility. It is critical to utilize the spectrum efficiently and ensure the coexistence of different wireless systems. Cognitive and dynamic spectrum access schemes provide a promising solution. In addition, new FCC regulations for unlicensed devices to operate in the TV whitespace requires that the secondary whitespace
- 42. 22 Next-Generation WirelessStandards and Their Integration with the Internet devices have cognitive radio and dynamic spectrum access capabilities and shall not interfere the operation of primary users. Several standard working groups and committees such as IEEE 802.22, IEEE SCC41, IEEE 802.19, and IEEE 802.11 are developing or plan to develop the standards for radio systems to operate in TV whitespace using cognitive radio technology. The standardization work on the mobile network architecture aims at opti- mizing network performance, improving cost efficiency, facilitating the fixed- mobile convergence and mass-market IP-based services with seamless mobility and global roaming capability, as well as enhanced network QoS and secu- rity. New network architecture to integrate various radio access technologies under IP is defined in 3GPP to support seamless global roaming, interwork- ing, and vertical handover between different access systems. In addition, IEEE 802.21 also defines a layer 2 solution to support mobility and media independent handover. Multihop wireless networks are emerging as a promising architecture to extend wireless coverage in a flexible and cost-effective way. They have broad applications in Internet access, emergency networks, public safety, and so forth. Technical solutions for multihop wireless networks are being specified in IEEE 802.11s, 802.16j, 802.16m, 802.15.5, and 3GPP LTE-advanced. IETF has also defined routing protocols for mobile ad hoc networks. 2.2 Radio Technologies in Next-Generation Wireless Standards 2.2.1 Emerging IEEE WLAN Standards The throughput of wireless LANs1 keeps increasing with advances in radio technologies. The new IEEE 802.11n standard2 is able to achieve up to 600 Mbps data rate when operating on 40 MHz bandwidth by using advanced phys- ical layer techniques including MIMO and channel bonding. 802.11n supports backward compatibility with 54 Mbps 802.11a/g radios. At the MAC layer, it is still based on carrier-sensing multiple access with collision avoidance (CSMA/CA) contention-based media access, called enhanced distributed chan- nel access (EDCA) and polling-based content-free media access, called hybrid coordination function controlled channel access (HCCA). To take advantages of high physical layer data rate and reduce protocol overhead, 802.11n defines two levels of aggregation at MAC layer. MAC Service Data Unit (MSDU) aggre- gation is processed at the top of MAC by packing multiple MSDUs into an aggregated MSDU, and MAC Protocol Data Unit (MPDU) aggregation is pro- cessed at the bottom of the MAC by packing multiple MPDUs into an aggregated MPDU. Block acknowledgment mechanism defined in 802.11e is also enhanced in 802.11n for better performance. These MAC features reduce the overhead, thus increasing the user-level data rate.
- 43. 2.2 Radio Technologiesin Next-Generation Wireless Standards 23 As wireless usage grows, there exists an increasing need for additional capac- ity. To provide comparable throughput as gigabit per second wired LAN prod- ucts, a new task group (TG), 802.11ac3 Very High Throughput for Operation in Bands below 6GHz, was formed in September 2008 to develop the enhance- ments to both the 802.11 PHY and MAC that enable modes of operation capable of supporting a maximum multistation (STA) throughput of at least 1 Gbps and a maximum single-link throughput of at least 500 Mbps while ensuring backward compatibility and coexistence with legacy IEEE 802.11 devices in the 5 GHz unlicensed band. 802.11ac will also provide enhancements over 802.11n on a set of other interdependent performance indicators including range of operation, spectrum efficiency, and power consumption. In order to provide higher throughput than IEEE 802.11n, Space-Division Multiple Access (SDMA) has been proposed in the 802.11ac TG to handle mul- tiple simultaneous communications between an access point and its associated stations. In general, SDMA employs multiuser MIMO (MU-MIMO) as a chan- nel access method and allows a station to transmit (or receive) signal to (or from) multiple other stations in the same band simultaneously. Compared to point-to- point MIMO or single-user MIMO used in 802.11n, MU-MIMO leverage the availability of multiple independent stations and their diverse channel conditions to create parallel spatial channels using beam forming for superior communica- tions performance in radio multiple access systems. Other techniques proposed to 802.11ac include backward compatibility and coexistence with 802.11n and other WiFi systems, support of more than 40 MHz channel bonding, and more than 4 MIMO antenna elements. The projected timeline for this task group is to have an initial draft by November 2010 and the approved standard in 2012. For wireless access in vehicular environments (WAVE), IEEE 802.11 TGp6 is specifying amendments to 802.11 to support Intelligent Transportation Systems (ITS) applications, which include data exchange between high-speed vehicles and between the vehicles and the roadside infrastructure in the licensed ITS band of 5.9 GHz. It specifies the functions and services that allow WAVE- conformant 802.11 stations to operate in a rapidly varying environment and to establish communications quickly each other. IEEE 1609 Family of Standards for Wireless Access in Vehicular Environments is a higher layer standard on which IEEE 802.11p is based. IEEE 802.11ad4 is developing technology to enable WLAN operation in the 60 GHz frequency band (typically 57–66 GHz). Due to high available bandwidth at 60 GHz band, multi-gigabit per second throughput can be achieved to support high throughput applications such as simultaneous streaming of multiple HDTV video streams or less compressed/uncompressed video streams, very-high-speed Internet access, wireless data bus for cable replacement, and so forth. It is expected that future mobile devices can be equipped with multiband WLAN
- 44. 24 Next-Generation WirelessStandards and Their Integration with the Internet access capabilities, short-range multi-Gbps throughput using 60 GHz band, and middle-range Gbps throughput operating at 5GHz band with seamless session transfer. 802.11ad is investigating the fast session transfer techniques between 60 GHz and 2.4/5 GHz. It is also studying the mechanisms that enable coexistence with other systems in the band, including IEEE 802.15.3c14 systems. 2.2.2 Emerging IEEE WPAN Standards Unlike wireless LANs, WPANs are used to convey information over relatively short distances, generally up to 10 meters, among a relatively few participants via power efficient and inexpensive networks. WPAN involves little or no infrastruc- ture. IEEE 802.15 Task Group 3c (TG3c) is developing a millimeter-wave-based high-rate WPAN. The 802.15.3c WPAN will operate in the 60 GHz unlicensed band. The standard defines three PHY modes with different modulation and channel coding techniques, which can achieve a data rate up to 5 Gbps on the 2.16 GHz channel bandwidth. 802.15.3c MAC is based on 802.15.3 piconet with enhancements. A piconet is an ad hoc network that allows a number of devices to communicate with each other. One device acts as a piconet coordinator (PNC) that provides the basic timing for the piconet with beacons, and manages the QoS requirements, power save modes, and access control to the piconet. A piconet is formed without preplanning and as long as the piconet is needed. Timing in the 802.15.3 piconet is based on the superframe composed of beacon, contention access period (CAP), and channel time allocation period (CTAP). The beacon is used to set the timing allocations and to communicate management information for the piconet. The CAP uses CSMA/CA as the medium access mechanism for commands and asynchronous data. CTAP is composed of channel time allocations (CTAs) that can be used for commands, isochronous streams, and asynchronous data connections. Sensor networks will become part of Internet to provide various types of information. The IEEE 802.15 TG4 has defined the PHY and MAC specifications for low data rate, low complexity, and low power consumption WPANs for inexpensive devices. The 802.15 TG4 and its later enhancements TG4a, TG4c, and TG4d have defined various physical layer modes. These PHYs use different techniques such as spread spectrum or ultra-wideband (UWB), support different data rates from 20 Kbps to 27.24 Mbps, operates at different frequency band to meet different country’s regulations – for example, 2.4 GHz ISM band, 915 MHz, 3 GHz to 5 GHz, and the like – and targets different applications such as sensors, interactive toys, smart badges, remote controls, and automation. The IEEE 802.15.4 standard is the basis for the ZigBee, WirelessHART, and MiWi specifications, each of which further offers a complete networking solution by developing the upper layers not covered by 802.15.4.
- 45. 2.2 Radio Technologiesin Next-Generation Wireless Standards 25 Depending on the application requirements, an IEEE 802.15.4 low-rate WPAN (LR-WPAN) may operate in either the star topology or the peer-to-peer (P2P) topology. It can be formed automatically. At the MAC layer, 802.15.4 LR- WPAN can use unslotted CSMA-CA or a superframe structure. A superframe contains contention free period (CFP) with guaranteed time slot for low-latency applications or applications requiring specific data bandwidth, as well as CAP with slotted CSMA-CA. The standard was developed with limited power supply availability of the devices in mind. A device may spend most of its opera- tional life in a sleep state, only periodically listening to the channel in order to determine whether a message is pending. Moreover, TG4f10 is currently defining the new PHY layer and enhancements to the 802.15.4 MAC layer for active radio-frequency identification (RFID) sys- tems. TG4g11 is defining an amendment to 802.15.4 to facilitate very large scale process control applications such as the utility smart-grid networks, capable of supporting large, geographically diverse networks with minimal infrastructure, and potentially millions of nodes. The IEEE 802.15 TG612 is developing a stan- dard for body area networks, and the IEEE 802.15 TG713 is defining a PHY and MAC standard for visible light communications (VLC). The low-power and low-cost sensor networks are expected to connect to the Internet in certain ways to provide various types of information. 2.2.3 Emerging 3GPP and IEEE Mobile Broadband Access Standards Regarding cellular networks, the ITU-R has commenced the process of develop- ing the International Mobile Telecommunications-Advanced (IMT-Advanced) systems standards26,27,28 for next-generation (4G) mobile networks. The first invitation for the submission of proposals for candidate radio interface tech- nologies (RITs) or a set of RITs (SRITs) for the IMT-Advanced was issued in March 2008. Under the current schedule, the deadline for submission of candi- date RIT and SRIT proposals was October 2009, and it is anticipated that the development of radio interface specification recommendations will be completed in 2011. According to ITU-R requirements, IMT-Advanced provides enhanced data rates to support advanced services and applications (100 Mbps for high mobil- ity and 1 Gbps for low mobility were established as target peak downstream rates), as well as improved spectrum efficiency and battery life. It will be fully IP-based system with voice carried by VoIP, which is different from hybrid circuit-switching and packet-switching IMT-2000 (3G) mobile communications systems. IMT-Advanced also has capabilities for supporting high-quality multi- media applications in a cost-efficient manner, providing a significant improve- ment in performance, quality of service, and security. It has key features such as worldwide roaming capability, compatibility of services within IMT and with
- 46. 26 Next-Generation WirelessStandards and Their Integration with the Internet fixed networks, capability of interworking with other radio access systems, and high-quality mobile services. Both IEEE 802.16m9 and 3GPP LTE-Advanced projects are developing advanced air interfaces to meet the cellular layer requirements of ITU-R IMT- Advanced. They are based on MIMO and OFDMA radio technologies with enhanced QoS and security. This reflects the technology trend from code divi- sion multiple access (CDMA) based hybrid circuit/packet switching 3G wireless systems to OFDMA-MIMO-based packet-switching 4G systems. OFDMA employs orthogonal frequency-division multiplexing (OFDM) dig- ital modulation scheme as a multiuser channel access strategy. It allows assign- ing subsets of subcarriers to individual users and simultaneously transmits to or receives signals from multiple users, achieving even better system spectral efficiency by leveraging channel frequency selectivity of multiple users and adaptive subcarrier assignment. Compared to CDMA, OFDMA can better combat multipath and achieve a higher MIMO spectral efficiency because it can have flatter frequency channels than a CDMA RAKE receiver. In addition, OFDM is more flexible in the use of spectrum than CDMA. CDMA requires a wide bandwidth to maintain high chip rates and high spectral efficiency, and it is complex to implement radios with capability of different chip rates and spectrum bandwidths. 3G radio interface such as wideband CDMA (W-CDMA) thus defines the fixed 5 MHz channel spectrum bandwidth. However, this limits the flexibility in system deployment and the maximum bandwidth per handset. OFDMA can easily control the data rate and error probability of each individual user by dynamically allocating resources in the time and frequency domains. It offers a cost-efficient solution for wide bandwidthcommunicationswithhighpeakrates. Therefore, itisconsidered as more suitable for next-generation broadband wireless networks. Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (E-UTRA) was introduced in 3GPP Release 8 in 2009. E-UTRA aims at significantly increasing data rates for mobile stations, lowering end-to- end latency for real-time communications, and reducing setup times for new sessions. It uses OFDMA for the downlink and Single Carrier Frequency Divi- sion Multiple Access (SC-FDMA) for the uplink and employs MIMO with up to four antennas per station. It supports both single-user MIMO and multiuser MIMO for downlink, and SDMA for uplink. Both frequency-division duplex- ing (FDD) mode and time-division duplexing (TDD) mode with a number of defined channel bandwidths between 1.25 and 20 MHz are supported to provide system deployment flexibility. The E-UTRA provides a peak downlink rate of 300 Mbps with 4 × 4 MIMO antennas and a peak uplink rate of 75 Mbps for a mobile user over 20 MHz channel, which greatly improves network capacity over 3G systems. MIMO enables ten times as many users per cell as 3GPP’s original W-CDMA radio access technology. E-UTRA also increased spectral
- 47. 2.3 Spectrum Managementand Cognitive Radio Networks 27 efficiency by two-to-four times compared to 3GPP CDMA-based UTRA inter- face. Improvements in architecture and signaling further reduce round-trip latency. It also enhances multicast service capability with single-frequency network support. In addition, E-UTRA improves coverage and battery life. However it is an entirely new air interface and incompatible with W-CDMA. E- UTRA is designed only to connect to 3GPP’s new IP-based evolved packet core network. 3GPP is developing further advancements for E-UTRA, also called LTE- advanced, to meet all the IMT-advanced requirements for 4G, which is compat- ible with E-UTRA and expected to be included in 3GPP Release 10. 3GPP’s proposal to ITU-R IMT-Advanced will be based on the LTE-Advanced. Multiple techniques including air interface optimization, scalable system bandwidth up to 100 MHz, enhanced precoding and forward error correction, hybrid OFDMA and SC-FDMA in uplink, relay nodes, advanced inter-eNodeB coordinated MIMO, and so forth are under investigation. IEEE 802.16m is amending the IEEE 802.16 OFDMA specification to meet the cellular layer requirements of IMT-Advanced, while providing continuing support and upgrade path for IEEE 802.16–2005 based WiMAX OFDMA sys- tem. It supports scalable bandwidths from 5 to 40 MHz, with a normalized peak data rate of 15.0 bps/Hz for downlink (4 × 4 MIMO) and 6.75 bps/Hz for uplink (2 × 4 MIMO). Both TDD and FDD modes are supported. IEEE 802.16m aims to be the IEEE candidate radio interface for IMT-Advanced 4G mobile networks and compete with 3GPP LTE-Advanced. Although 802.16m and E-UTRA adopts similar technologies such as OFDMA and MIMO, the differences in detail MAC and PHY layer design make them incompatible. 802.16m will be in conformance with the IEEE 802 architecture defined in 802.1 and provide seamless interworking with other IEEE 802 wired and wireless systems. 2.3 Spectrum Management and Cognitive Radio Networks Cognitive radio technology allows either a network or a wireless node to dynam- ically change its transmission or reception parameters to communicate effi- ciently and to avoid interference with licensed or unlicensed users based on the active monitoring of its operation environment. In general, a cognitive radio system is reconfigurable and can take various external and internal radio envi- ronments such as radio frequency spectrum, user behavior, and network state into account to make decision, and adapts various parameters such as frequency spectrum, transmit power, transmit mode, media access method, and so on. More specifically, cognitive radios intelligently access and share radio spectrum by obtaining and sensing spectrum operating environment for efficient usage of licensed/unlicensed spectrum.
- 48. 28 Next-Generation WirelessStandards and Their Integration with the Internet The radio frequency spectrum is a limited and valuable resource, but its usage is unbalanced. Some frequency bands are heavily used, for example, cel- lular network bands. However, a lot of frequency bands are inefficiently utilized, for example, amateur radio and paging frequencies. Furthermore, spectrum uti- lization depends strongly on time and place. Fixed spectrum allocation prevents the frequency spectrum unused by primary users from being used by unlicensed secondary users. Spectrum utilization can be improved significantly by allowing secondary users to access spectrum holes in the licensed band whenever it would not cause any interference to primary users. Cognitive radio has been proposed as the means for secondary users to utilize the spectrum holes, share the spectrum among them, and avoid the spectrum whenever primary users present. In November 2008, the Federal Communications Commission (FCC) issued its report and order for unlicensed use of the TV white spaces. The TV white spaces are the frequencies that allocated to TV broadcasting, wireless micro- phones, and the like, but not used locally. Especially after full-power analog television broadcasts ceased operating in June 2009, many channels had freed up. The new FCC rules allow unlicensed devices to operate in the broadcast television spectrum at locations where that spectrum is not being used, given the secondary white space devices have cognitive radio and dynamic spec- trum access capabilities, and shall not interfere the operation of primary users. The FCC currently requires that secondary devices must consult a frequently updated geo-location database to determine which channels are available for use at a given location. Other regulatory bodies such as ITU, European Radio Spectrum Policy Group (ERSPG), U.K. Ofcom, and Japan’s Ministry of Internal Affairs and Communication (MIC) are also considering similar regulations. Various proposals have advocated using TV white spaces to provide differ- ent services. The IEEE 802.2216 working group is developing a standard for wireless regional area network (WRAN) that will operate in unused television channels. 802.22 WRAN mainly aims at providing wireless broadband access in rural areas using vacant TV channels in the VHF and UHF bands while avoiding interference to the broadcast incumbents in these bands. It typically operates with a coverage radius of 17 km to 30 km. 802.22 WRAN system uses TDMA/OFDMA similar to WiMAX networks, but it does not support MIMO because of the large antenna separation requirement at its low operating frequency. Especially 802.22 specifies cognitive radio capability at the MAC/PHY air interface for dynamic frequency access. It can adjust to the location-dependent and time-variable spectrum availability to avoid interference to incumbents on a real-time basis. Specifically, 802.22 includes two new modules, namely Spec- trum Sensing Function (SSF) and Geo-location module. The spectrum-sensing function monitors the RF spectrum of the television channels for a set of signal types and reports the results. The location information is important to protect
- 49. 2.4 All IPMobile Networks 29 TV incumbent transmissions. The TV contours to be protected from interference are stored in a database. The base station (BS) controls the maximum allowed transmit power at individual CPEs using the collective knowledge of channel sensing, the CPE location, the TV operation database information, and so on. The standard also specifies the protocols for coexistence of multiple 802.22 cells. Several other working groups in IEEE 802 are also studying TV white space. 802.11 has formed a task group 802.11af7 for WLAN operation in TV white space 802.19, which has started studying coexistence of two or more unlicensed wireless networks such as WLANs, WMANs, WRANs, and ad hoc networks when they operate in the TV white space. Possible coexistence mechanisms under consideration include dynamic frequency selection and transmit power control, listen-before-talk media access or time division multiplexing of different wireless technologies, message-based on-demand spectrum contention based on coexistence beaconing or backhaul, as well as control through a centralized coexistence manager, coexistence database, or spectrum broker. IEEE Standards Coordinating Committee (SCC) 41 is also developing stan- dards related to dynamic spectrum access networks. The focus is on spectrum management, coexistence, reconfiguration, and dynamic spectrum access for cognitive radio. ITU and ETSI have also started the standard activities related to cognitive radio. In particular, ETSI’s Reconfigurable Radio System (RRS) technical committee is defining the system functionalities related to spectrum management and joint radio resource management across heterogeneous access technologies, developing a functional architecture, and studying the concept of a Cognitive Pilot Channel (CPC) as an enabler to support the management of the reconfigurable radio systems. 2.4 All IP Mobile Networks As part of LTE/System Architecture Evolution (SAE) effort, 3GPP defined the Evolved Packet System (EPS), an IP-based flat mobile network, to meet the increasing user and service demands, and to conform to Internet protocols for converging mobile and fixed network services. It aims at providing improved experience for users and increased performance and reduced cost for network operators. 3GPP All IP Network (AIPN) architecture represents its vision that next-generation mobile networks are based on core Internet protocols. The existing 2G/3G networks consist of two subdomains: circuit switching for voice and packet switching for data, as shown in Figure 2.2.18 The EPS unifies these two subdomains into a single end-to-end AIPN, in which voice calls are handled by VoIP using IP Multimedia Subsystem (IMS). EPS is able to integrate and support different radio access systems such as 3GPP radio access (LTE, 3G, and 2G) and non-3GPP radio access (CDMA 2000, WLAN, WiMAX),
- 50. 30 Next-Generation WirelessStandards and Their Integration with the Internet UTRAN MSC MSC Legacy circuit- switched services 2G/3G 3GPP core SGSN GGSN Packet data networks (IP services, e.g. IMS, Internet, etc.) GERAN Figure 2.2. Simplified architecture of the 2G/3G 3GPP network. as well as fixed access (Ethernet, DSL, cable, and fiber) with one common packet core network. It provides diversified mobile services with convergence to IP and enables the introduction of new business models and services, for example, partnering and revenue sharing with third-party content and application providers. It also supports incremental deployment because at the beginning, LTE may be only deployed at most needed areas and coexistence with legacy networks. The IMS was originally standardized by the 3GPP to deliver IP multimedia services over cellular access networks (UMTS/GPRS networks). It was later enhanced to support other network accesses including Wireless LAN, CDMA 2000, and fixed networks. The IMS includes various control function compo- nents such as call session control functions (CSCF) and application servers, for example, the session initiation protocol (SIP) application server, service central- ization and continuity (SCC) application server, with standard interfaces based on SIP and many related protocols. It controls the services with user registration, origination, termination, transfer, and release of multimedia sessions. The IMS provides a horizontal control layer that isolates the access networks from the service layer, and is able to maintain the services even when the user is moving across different access networks and terminal types. The user can connect to an IMS system from any access network through IP connectivity as long as it runs a SIP agent. The 2G or 3G circuit-switched network can also be supported as an access network to the IMS through gateways. As shown in Figure 2.3,18,19 the flat EPS architecture consists of two parts: the access network and the core network. 3GPP LTE specifies a new access network, E-UTRAN, which offers higher bandwidth, better spectrum efficiency, and better coverage. The core network is called evolved packet core (EPC), which consists of several major elements, including Serving Gateway (S-GW), Packet Data Network (PDN) Gateway (P-GW) and Enhanced Packet Data Gate- way (ePDG), Mobility Management Entity (MME), Policy and Charging Rules
- 51. Another Random ScribdDocument with Unrelated Content
- 52. all sailing thereupontowards the Great Harbour. Meanwhile, from his elevated position Antony saw the whole of his cavalry suddenly gallop over to Octavian’s lines, and he thus found himself left only with his infantry, who, of course, were no match for the enemy. It was useless to struggle further, and, giving up all hope, he fled back into the city, crying out that Cleopatra had betrayed him. As he rushed into the Palace, followed by his distracted officers, smiting his brow and calling down curses on the woman who, he declared, had delivered him into the hands of enemies made for her sake, the Queen fled before him from her apartments, as though she feared that in his fury and despair he might cut her down with his sword. Alone with her two waiting-women, Iras and Charmion, she ran as fast as she could through the empty halls and corridors of the Palace, and at length, crossing the deserted courtyard, she reached the mausoleum adjoining the temple of Isis. The officials, servants, and guards, it would seem, had all fled at the moment when the cry had arisen that the fleet and the cavalry had deserted; and there were probably but a few scared priests in the vicinity of the temple, who could hardly have recognised the Queen as she panted to the open door of the tomb, deserted by the usual custodians. The three women rushed into the dimly-lighted hall, bolting and barring the door behind them, and no doubt barricading it with benches, offering-tables, and other pieces of sacerdotal furniture. They then made their way to the habitable rooms on the upper floor, where they must have flung themselves down upon the rich couches in a sort of delirium of horror and excitement, Cleopatra herself preparing for immediate suicide. From the window they must have seen some of Antony’s staff hastening towards them, for presently they were able to send a message to tell him that the Queen was on the point of killing herself. After a short time, however, when the tumult in her brain had somewhat subsided, Cleopatra made up her mind to wait awhile before taking the final step, so that she might ascertain Octavian’s attitude towards her; and, having determined upon this course of action, she seems to have composed herself as best she could, while through the eastern windows, her eyes staring
- 53. over the summersea, she watched the Egyptian ships and those of the enemy rowing side by side into the Great Harbour. There is no reason to suppose that Cleopatra had betrayed her husband, or that she was in any way a party to the desertions which had just taken place. The sudden collapse of their resistance, while yet it was but mid-morning, must have come to her as a staggering shock; and Antony’s accusations were doubtless felt to be only in keeping with the erratic behaviour which had characterised his last years. On the previous day Antony had offered a large sum of money to every one of Octavian’s legionaries who should desert; and it is more than likely that Octavian had made a similar offer to the Egyptian sailors and soldiers. Only a year previously these sailors had fraternised with the Romans of the Antonian party in the Gulf of Ambracia, and the latter, having deserted to Octavian after the battle of Actium, were now present in large numbers amongst the opposing fleet. The Egyptians were thus called upon to fight with their friends whose hospitality they had often accepted, and whose fighting qualities, now that they were combined with Octavian’s victorious forces, they had every reason to appreciate. Their desertion, therefore, needed no suggestion on the part of Cleopatra: it was almost inevitable. Antony, however, was far too distracted and overwrought to guard his tongue, and he seems to have paced his apartments in the Palace in a condition bordering upon madness, cursing Cleopatra and her country, and calling down imprecations upon all who had deserted him. Presently those of his staff who had followed the Queen to her mausoleum brought him the news that she had killed herself, for so they had interpreted her message; and instantly Antony’s fury seems to have left him, the shock having caused a collapse of his energy. At first he was probably dazed by the tidings; but when their full significance had penetrated to his bewildered brain there was no place left for anger or suspicion. “Now Antony,” he cried, “why delay longer? Fate has taken away the only thing for which you could say you still wanted to live.” And with these words he rushed into his bedchamber, eagerly tearing off his armour, and
- 54. calling upon hisslave Eros to assist him. Then, as he bared the upper part of his body, he was heard to talk aloud to the Queen, whom he believed to be dead. “Cleopatra,” he said, “I am not sad to be parted from you now, for I shall soon be with you; but it troubles me that so great a general should have been found to have slower courage than a woman.” Not long previously he had made Eros solemnly promise to kill him when he should order him to do so; and now, turning to him, he gave him that order, reminding him of his oath. Eros drew his sword, as though he intended to do as he was bid, but suddenly turning round, he drove the blade into his own breast, and fell dying upon the floor. Thereupon Antony bent down over him and cried to him as he lost consciousness, “Well done, Eros! Well done!” Then, picking up the sword, he added, “You have shown your master how to do what you had not the heart to do yourself;” and so saying, he drove the sword upwards into his breast from below the ribs, and fell back upon his bed. The wound, however, was not immediately mortal, and presently, the flow of blood having ceased, he recovered consciousness. Some of the Egyptian servants had gathered around him, and now he implored them to put him out of his pain. But when they realised that he was not dead they rushed from the room, leaving him groaning and writhing where he lay. Some of them must have carried the news to the Queen as she sat at the window of the mausoleum, for, a few moments later, a certain Diomedes, one of her secretaries, came to Antony telling him that she had not yet killed herself, and that she desired his body to be brought to her. Thereupon Antony eagerly gave orders to the servants to carry him to her, and they, lifting him in their arms, placed him upon an improvised stretcher and hurried with him to the mausoleum. A crowd seems now to have collected around the door of the building, and when the Queen saw the group of men bringing her husband to her, she must have feared lest some of them, seeking a reward, would seize her as soon as they had entered her stronghold and carry her alive to Octavian. Perhaps, also, it was a difficult matter to shoot back the bolts of the door which in her excitement she had
- 55. managed to drivedeep into their sockets. She, therefore, was unable to admit Antony into the mausoleum; and there he lay below her window, groaning and entreating her to let him die in her arms. In the words of Plutarch, Cleopatra thereupon “let down ropes and cords to which Antony was fastened; and she and her two women, the only persons she had allowed to enter the mausoleum, drew him up. Those who were present say that nothing was ever more sad than this spectacle, to see Antony, covered all over with blood and just expiring, thus drawn up, still holding up his hands to her, and raising up his body with the little force he had left. And, indeed, it was no easy task for the women; for Cleopatra, with all her strength clinging to the rope and straining at it with her head bent towards the ground, with difficulty pulled him up, while those below encouraged her with their cries and joined in all her efforts and anxiety.” The window must have been a considerable distance from the ground, and I do not think that the three women could ever have succeeded in raising Antony’s great weight so far had not those below fetched ladders, I suppose, and helped to lift him up to her, thereafter, no doubt, watching the terrible scene from the head of these ladders outside the window. Dragging him through the window the women carried him to the bed, upon which he probably swooned away after the agonies of the ascent. Cleopatra was distracted by the pitiful sight, and fell into uncontrolled weeping. Beating her breast and tearing her clothes, she made some attempts, at the same time, to stanch the scarlet stream which flowed from his wound; and soon her face and neck were smeared with his blood. Flinging herself down by his side she called him her lord, her husband, and her emperor. All her pity and much of her old love for him was aroused by his terrible sufferings, and so intent was she upon his pain that her own desperate situation was entirely forgotten. At last Antony came to his senses, and called for wine to drink; after which, having revived somewhat, he attempted to soothe the Queen’s wild lamentations, telling her to make her terms with Octavian, so far as might honourably be done, and advising her to trust only a certain Proculeius amongst all the
- 56. friends of theconqueror. With his last breath, he begged her, says Plutarch, “not to pity him in this last turn of fate, but rather to rejoice for him in remembrance of his past happiness, who had been of all men the most illustrious and powerful, and in the end had fallen not ignobly, a Roman by a Roman vanquished.” With these words he lay back upon the bed, and soon had breathed his last in the arms of the woman whose interests he had so poorly served, and whom now he left to face alone the last great struggle for her throne and for the welfare of her son.
- 57. CHAPTER XX. THE DEATHOF CLEOPATRA AND THE TRIUMPH OF OCTAVIAN. Cleopatra’s situation was at this moment terrible in the extreme. The blood-stained body of her husband lay stretched upon the bed, covered by her torn garments which she had thrown over it. Charmion and Iras, her two waiting-women, were probably huddled in the corner of the room, beating their breasts and wailing as was the Greek habit at such a time. Below the open window a few Romans and Egyptians appear to have gathered in the sun-baked courtyard; and, I think, the ladders still rested against the wall where they had been placed by those who had helped to raise Antony up to the Queen. It must now have been early afternoon, and the sunlight of the August day, no doubt, beat into the room, lighting the disarranged furniture and revealing the wet blood-stains upon the tumbled carpets over which the dying man’s heavy body had been dragged. From the one side the surge of the sea penetrated into the chamber; from the other the shouts of Octavian’s soldiers and the clattering of their arms came to Cleopatra’s ears, telling her of the enemy’s arrival in the Palace. She might expect at any moment to be asked to surrender, and more than probably an attempt would be made to capture her by means of an entry through the window. She had determined, however, never to be made prisoner in this manner, and she had, no doubt, given it to be clearly understood that any effort to seize her would be her signal for firing the funeral pyre which had been erected in
- 58. the adjoining roomand destroying herself upon it. To be made a captive probably meant her degradation at Octavian’s Triumph and the loss of her throne; but to surrender by mutual arrangement might assure her personal safety and the continuity of her dynasty. With this in view, it seems likely that she now armed her two women to resist any assault upon the windows, and told them to warn all who attempted to climb the ladders that she, with her priceless jewellery and treasures, would be engulfed in the flames before ever they had reached to the level of her place of refuge. Antony had been dead but a few minutes when Proculeius, of whom he had spoken to Cleopatra just before he expired, arrived upon the scene, demanding, in the name of Octavian, an audience with the Queen. He knocked upon the barred door of the main entrance to the mausoleum, calling upon Cleopatra to admit him, and the sound must have echoed through the hall below and come to her ears, where she listened at the top of the stairs, like some ominous summons from the powers of the Underworld; but, fearing that she might be taken prisoner, she did not dare open to him, even if she could have shot back the heavy bolts, and she must have paced to and fro beside her husband’s corpse in an agony of indecision. At last, however, she ran down the marble staircase to the dimly-lighted hall below, and, standing beside the barricade which she had constructed against the inner side of the door, called out to Proculeius by name. He answered her from the outside, and in this manner they held a short parley with one another, she offering to surrender if she could receive Octavian’s word that her Kingdom of Egypt would be given to her son Cæsarion, and Proculeius replying only with the assurance that Octavian was to be trusted to act with clemency towards her. This was not satisfactory to her, and presently the Roman officer returned to his master, leaving Cleopatra undisturbed until late in the afternoon. He described the Queen’s situation to Octavian, and pointed out to him that it would probably not be difficult to effect an entrance to the mausoleum by means of the ladders, and that, with speed and a little manœuvring, Cleopatra could be seized before she had time to
- 59. fire the pyre.Thereupon Octavian sent him with Cornelius Gallus, 139 who had now reached Alexandria, to attempt her capture, and the latter went straight to the door of the mausoleum, knocking upon it to summon the Queen. Cleopatra at once went down the stairs and entered into conversation with Cornelius Gallus through the closed door; and it would seem that her two women, perhaps eager to hear what was said, left their post at the window of the upper room and stood upon the steps behind her. As soon as the Queen was heard to be talking and reiterating her conditions of surrender, Proculeius ran round to the other side of the building, and, adjusting the ladders, climbed rapidly up to the window, followed by two other Roman officers. Entering the disordered room, he ran past the dead body of Antony and hurried down the stairs, at the bottom of which he encountered Charmion and Iras, while beyond them in the dim light of the hall he saw Cleopatra standing at the shut door, her back turned to him. One of the women uttered a cry, when she saw Proculeius, and called out to her mistress: “Unhappy Cleopatra, you are taken prisoner!” At this the Queen sprang round, and, seeing the Roman officer, snatched a dagger from its sheath at her waist and raised it for the stroke which should terminate the horror of her life. Proculeius, however, was too quick for her. He sprang at her with a force which must have hurled her back against the door, and, seizing her wrist, shook the dagger from her small hand. Then, holding her two arms at her side, he caused his men to shake her dress and to search her for hidden weapons or poison. “For shame, Cleopatra,” he said to her, scolding her for attempting to take her life; “you wrong yourself and Octavian very much in trying to rob him of so good an opportunity of showing his clemency, and you would make the world believe that the most humane of generals was a faithless and implacable enemy.” He then seems to have ordered his officers to remove the barriers and to open the door of the mausoleum, whereupon Cornelius Gallus and his men were able to assist him to guard the Queen and her two women. Shortly after this, Octavian’s freedman, Epaphroditus, arrived with orders to treat Cleopatra with all possible gentleness and civility, but to take the strictest
- 60. precautions to preventher injuring herself; and, acting on these instructions, the Roman officers seem to have lodged the Queen under guard in one of the upper rooms of the mausoleum, after having made a thorough search for hidden weapons or poisons. Just before sunset Octavian made his formal entry into Alexandria. He wished to impress the people of the city with the fact of his benevolent and peace-loving nature, and therefore he made a certain Alexandrian philosopher named Areius, for whom he had a liking, ride with him in his chariot. As the triumphal procession passed along the beautiful Street of Canopus, Octavian was seen by the agitated citizens to be holding the philosopher’s hand and talking to him in the most gentle manner. Stories soon went the rounds that when the conqueror had received the news of Antony’s death he had shed tears of sorrow, and had read over to his staff some of his enemy’s furious letters to him and his own moderate replies, thus showing how the quarrel had been forced upon him. Orders now seem to have been issued forbidding all outrage or looting; and presently the frightened Alexandrians ventured from their hiding- places, most of the local magnates being ordered to gather themselves together in the Gymnasium. Here, in the twilight, Octavian rose to address them; and as he did so, they all prostrated themselves upon the ground before him in abject humiliation. Commanding them to rise, he told them that he freely acquitted them of all blame: firstly, in memory of the great Alexander who had founded their city; secondly, for the sake of the city itself which was so large and beautiful; thirdly, in honour of their god Serapis; 140 and lastly, to gratify his dear friend Areius, at whose request he was about to spare many lives. Having thus calmed the citizens, who now must have hailed him as a kind of deliverer and saviour, he retired to his quarters, whence, in his sardonic manner, he appears to have issued orders for the immediate slaughter of those members of the court of Cleopatra and Antony for whom Areius had not any particular liking. The unfortunate Antyllus, Antony’s son, having been betrayed to
- 61. Octavian by hisfaithless tutor Theodorus, was at once put to death in the temple erected by Cleopatra to Julius Cæsar, whither he had fled. As the executioner cut off the boy’s head, Theodorus contrived to steal a valuable jewel which hung round his neck; but the theft was discovered, and he was carried before Octavian, who ordered him to be crucified forthwith. A strict guard was set over the two children of Cleopatra, Ptolemy and Cleopatra Selene, 141 who were still in Alexandria; and Octavian seems to have given Cleopatra to understand that if she attempted to kill herself he would put these two children to death. Thus he was able to assure himself that she would refrain from taking her life, for, as Plutarch says, “before such engines her purpose (to destroy herself) shook and gave way.” Antony’s body was now, I suppose, prepared for burial. Though mummification was still often practised in Alexandria by Greeks and Egyptians, I do not think that any elaborate attempt was made to embalm the corpse, and it was probably ready for the funeral rites within a few days. Out of respect to the dead general a number of Roman officers and foreign potentates who were with Octavian’s army begged to be allowed to perform these rites at their own expense; but in deference to Cleopatra’s wishes the body was left in the Queen’s hands, and instructions were issued that her orders were to be obeyed in regard to the funeral. Thus Antony was buried, with every mark of royal splendour and pomp, in a tomb which had probably long been prepared for him, not far from his wife’s mausoleum. Cleopatra followed him to his grave, a tragic, piteous little figure, surrounded by a group of her lamenting ladies; and, while the priests burnt their incense and uttered their droning chants, the Queen’s fragile hands ruthlessly beat her breasts as she called upon the dead man by his name. In these last terrible hours only the happier character of her relationship with Antony was remembered, and the recollection of her many disagreements with him were banished from her mind by the piteous scenes of his death, and by the thought of his last tender words to her as he lay groaning upon her bed. In her extreme loneliness she must have now desired his buoyant company of earlier years with an intensity
- 62. which she couldhardly have felt during his lifetime; and it must have been difficult indeed for her to refrain from putting an end to her miserable life upon the grave of her dead lover. Yet Octavian’s threat in regard to her children held her hand; and, moreover, even in her utter distress, she had not yet abandoned her hope of saving Egypt from the clutch of Rome. Her own dominion, she knew, was over, and the best fate which she herself could hope for was that of an unmolested exile; yet Octavian’s attitude to her indicated in every way that he would be willing to leave the throne to her descendants. She did not know how falsely he was acting towards her, how he was making every effort to encourage hope in her heart in order that he might bring her alive to Rome to be exhibited in chains to the jeering populace. She did not understand that his messages of encouragement, and even of affection, to her were written with sardonic cunning, that his cheerful assurances in regard to her children were made at a time when he was probably actually sending messages post-haste to Berenice to attempt to recall Cæsarion in order to put him to death. She did not understand Octavian’s character: perhaps she had never even seen him; and she hoped somehow to make a last appeal to him. She had played her wonderful game for the amalgamation of Egypt and Rome into one vast kingdom, ruled by her descendants and those of the great Julius Cæsar, and she had lost. But there was yet hope that out of the general wreck she might save the one asset with which she had started her operations—the independent throne of Egypt; and to accomplish this she must live on for a while longer, and must face with bravery the nightmare of her existence. Coming back, after the funeral, to her rooms in the mausoleum, wherein she had now decided to take up her residence, she fell into a high fever; and there upon her bed she lay in delirium for several days. She suffered, moreover, very considerable pain, due to the inflammation and ulceration caused by the blows which she had rained upon her delicate body in the abandonment of her despair. Over and over again she was heard to utter in her delirium the desolate cry, “I will not be exhibited in his Triumph,” and in her
- 63. distress she beggedrepeatedly to be allowed to die. At one time she refused all food, and begged her doctor, a certain Olympus, to help her to pass quietly out of the world. 142 Octavian, however, hearing of her increasing weakness, warned her once more that unless she made an effort to live he would not be lenient to her children; whereupon, as though galvanised into life by this pressure upon her maternal instincts, she made the necessary struggle to recover, obediently swallowing the medicine and stimulants which were given to her. Thus the hot August days passed by, and at length the Queen, now fragile and haggard, was able to move about once more. Her age at this time was thirty-eight years, and she must have lost that freshness of youth which had been her notable quality; but her brilliant eyes had now perhaps gained in wonder by the pallor of her face, and the careless arrangement of her dark hair must have enhanced her tragic beauty. The seductive tones of her voice could not have been diminished, and that peculiar quality of elusiveness may well have been accentuated by her illness and by the nervous strain through which she had passed. Indeed, her personal charm was still so great that a certain Cornelius Dolabella, one of the Roman officers whose duty it was to keep watch over her, speedily became her devoted servant, and was induced to promise that he would report to her any plans in regard to her welfare which Octavian should disclose. On August 28th, as she lay upon a small pallet-bed in the upper room, gazing in utter desolation, as I imagine, over the blue waters of the Mediterranean, her women ran in to her to tell her that Octavian had come to pay his respects to her. He had not yet visited her, for he had very correctly avoided her previous to and during Antony’s funeral; and since that time she had been too ill to receive him. Now, however, she was convalescent, and the conqueror had arrived unexpectedly to congratulate her, as etiquette demanded, upon her recovery. He walked into the room before the Queen had time to prepare herself; and Plutarch describes how, “on his
- 64. entering, she sprangfrom her bed, having nothing on but the one garment next her body, and flung herself at his feet, her hair and face looking wild and disfigured, her voice trembling, and her eyes sunken and dark. The marks of the blows which she had rained upon herself were visible about her breast, and altogether her whole person seemed to be no less afflicted than was her spirit. But for all this, her old charm and the boldness of her youthful beauty had not wholly left her, and, in spite of her present condition, still shone out from within and allowed itself to appear in all the expressions of her face.” The picture of the distraught little Queen, her dark hair tumbled over her face, her loose garment slipping from her white shoulders, as she crouches at the feet of this cold, unhealthy-looking man, who stands somewhat awkwardly before her, is one which must distress the mind of the historian who has watched the course of Cleopatra’s warfare against the representative of Rome. Yet in this scene we are able to discern her but stripped of the regal and formal accessories which have often caused her to appear more imposing and awe- inspiring than actually her character justified. She was essentially a woman, and now, in her condition of physical weakness, she acted precisely as any other overwrought member of her sex might have behaved under similar circumstances. Her wonderful pluck had almost deserted her, and her persistence of purpose was lost in the wreck of all her hopes. We have often heard her described as a calculating woman, who lived her life in studied and callous voluptuousness, and who died in unbending dignity; but, as I have tried to indicate in this volume, the Queen’s nature was essentially feminine—highly-strung, and liable to rapid changes from joy to despair. Keen, independent, and fearless though she was, she was never a completely self-reliant woman, and in circumstances such as those which are now being recorded we obtain a view of her character, which shows her to have been capable of needing desperately the help and sympathy of others. Octavian raised her to her feet, and, assisting her once more on to her bed, sat himself down beside her. At first she talked to him in
- 65. a rambling manner,justifying her past movements, and attributing certain actions, such, I suppose, as her hiding in the mausoleum, to her fear of Antony; but when Octavian pointed out to her the discrepancies in her statements she made no longer any attempt to excuse her conduct, begging him only not to take her throne from her son, and telling him that she was willing enough to live if only he would insure the safety of her country and dynasty, and would be merciful to her children. Then, rising from the bed, she brought to Octavian a number of letters written to her by Julius Cæsar, and also one or two portraits of him painted for her during his lifetime. “You know,” she said, 143 “how much I was with your father, 144 and you are aware that it was he who placed the crown of Egypt upon my head; but, so that you may know something of our private affairs, please read these letters. They are all written to me with his own hand.” Octavian must have turned the letters over with some curiosity, but he does not seem to have shown a desire to read them; and, seeing this, Cleopatra cried: “Of what use are all these letters to me? Yet I seem to see him living again in them.” The thought of her old lover and friend, and the memories recalled by the letters and portraits before her seem to have unnerved her; and, being in so overwrought and weak a condition, she now broke down completely. Between her sobs she was heard to exclaim, “Oh, I wish to God you were still alive,” as though referring to Julius Cæsar. Octavian appears to have consoled her as best he could; and at length she seems to have agreed that, in return for his clemency, she would place herself entirely in his hands, and would hand over to him without reserve all her property. One of her stewards, named Seleucus, happened to be awaiting her orders in the mausoleum at the time, and, sending for him, she told him to hand over to Octavian the list which they together had lately made of her jewellery and valuables, and which now lay with her other papers in the room. Seleucus seems to have read the document to Octavian; but, wishing to ingratiate himself with his new master, and thinking
- 66. that loyalty toCleopatra no longer paid, he volunteered the information that various articles were omitted from the list, and that the Queen was purposely secreting these for her own advantage. At this Cleopatra sprang from her bed, and, dashing at the astonished steward, seized him by the hair, shook him to and fro, and furiously slapped his face. So outraged and overwrought was she that she might well have done the man some serious injury had not Octavian, who could not refrain from laughing, withheld her and led her back to her seat. “Really it is very hard,” she exclaimed to her visitor, “when you do me the honour to come to see me in this condition I am in, that I should be accused by one of my own servants of setting aside some women’s trinkets—not so as to adorn my unhappy self, you may be sure, but so that I might have some little presents by me to give to your sister Octavia and your wife Livia, that by their intercession I might hope to find you to some extent disposed to mercy.” Cæsar was delighted to hear her talk in this manner, for it seemed to indicate that she was desirous of continuing to live; and he was most anxious that she should do so, partly, as I have said, that he might have the satisfaction of parading her in chains through the streets of Rome, and partly, perhaps, in order to show, thereafter, his clemency and his respect to the late Dictator’s memory by refraining from putting her to death. He therefore told her that she might dispose of these articles of jewellery as she liked; and, promising that his usage of her would be merciful beyond her expectation, he brought his visit to a close, well satisfied that he had won her confidence, and that he had entirely deceived her. In this, however, he was mistaken, and he was himself deceived by her. Cleopatra had observed from his words and manner that he wished to exhibit her in Rome, and that he had little intention of allowing her son Cæsarion to reign in her place, but purposed to seize Egypt on behalf of Rome. Far from reassuring her, the interview had left her with the certainty that the doom of the dynasty was sealed; and already she saw clearly that there was nothing left for which to live. Presently a messenger from Cornelius
- 67. Dolabella came toher, and broke the secret news to her that Octavian, finding her now recovered from her illness, had decided to ship her off to Rome with her two children in three days’ time or less. It is possible, also, that Dolabella was already able to tell her that there was no hope for her son Cæsarion, for that Octavian had decided to kill him so soon as he could lay hands on him, realising, at the instance of his Alexandrian friend Areius, that it was unwise to leave at large one who claimed to be the rightful successor of the great Dictator. On hearing this news the Queen determined to kill herself at once, for her despair was such that the fact of existence had become intolerable to her. In her mind she must have pictured Octavian’s Triumph in Rome, in which she and her children would figure as the chief exhibits. She would be led in chains up to the Capitol, even as she had watched her sister Arsinoe paraded in the Triumph of Julius Cæsar; and she could hear in imagination the jeers and groans of the townspeople, who would not fail to remind her of her former boast that she would one day sit in royal judgment where then she would be standing in abject humiliation. The thought, which of itself was more than she could bear, was coupled with the certainty that, were she to prolong her life, she would have to suffer also the shock of her beloved son’s cruel murder, for already his death seemed inevitable. Having therefore made up her mind, she sent a message to Octavian asking his permission for her to visit Antony’s tomb, in order to make the usual oblations to his spirit. This was granted to her, and upon the next morning, August 29th, she was carried in her litter to the grave, accompanied by her women. Arriving at the spot she threw herself upon the gravestone, embracing it in a very passion of woe. “Oh, dearest Antony,” she cried, the tears streaming down her face, “it is not long since with these hands I buried you. Then they were free; now I am a captive; and I pay these last duties to you with a guard upon me, for fear that my natural griefs and sorrows should impair my servile body and make it less fit to be exhibited in their Triumph over you. Expect no further offerings or
- 68. libations from me,Antony; these are the last honours that Cleopatra will be able to pay to your memory, for she is to be hurried far away from you. Nothing could part us while we lived, but death seems to threaten to divide us. You, a Roman born, have found a grave in Egypt. I, an Egyptian, am to seek that favour, and none but that, in your country. But if the gods below, with whom you now are dwelling, can or will do anything for me, since those above have betrayed us, do not allow your living wife to be abandoned, let me not be led in Triumph to your shame; but hide me, hide me: bury me here with you. For amongst all my bitter misfortunes nothing has been so terrible as this brief time that I have lived away from you.” 145 For some moments she lay upon the tombstone passionately kissing it, her past quarrels with the dead man all forgotten in her desire for his companionship now in her loneliness, and only her earlier love for him being remembered in the tumult of her mind. Then, rising and placing some wreaths of flowers upon the grave, she entered her litter and was carried back to the mausoleum.
- 69. Vatican.] [Photograph byAnderson. THE NILE. AN EXAMPLE OF ALEXANDRIAN ART. As soon as she had arrived she ordered her bath to be prepared, and having been washed and scented, her hair being carefully plaited around her head, she lay down upon a couch and partook of a sumptuous meal. After this she wrote a short letter to Octavian, asking that she might be buried in the same tomb with Antony; and, this being despatched, she ordered everybody to leave the mausoleum with the exception of Charmion and Iras, as though she did not wish to be disturbed in her afternoon’s siesta. The doors were then closed, and the sentries mounted guard on the outside in the usual manner. When Octavian read the letter which Cleopatra’s messenger had brought him, he realised at once what had happened, and hastened
- 70. to the mausoleum.Changing his mind, however, he sent some of his officers in his place, who, on their arrival, found the sentries apprehensive of nothing. Bursting open the door they ran up the stairs to the upper chamber, and immediately their worst fears were realised. Cleopatra, already dead, lay stretched upon her bed of gold, arrayed in her Grecian robes of state, and decked with all her regal jewels, the royal diadem of the Ptolemies encircling her brow. Upon the floor at her feet Iras was just breathing her last; and Charmion, scarce able to stand, was tottering at the bedside, trying to adjust the Queen’s crown. One of the Roman officers exclaimed angrily: “Charmion, was this well done of your lady?” Charmion, supporting herself beside the royal couch, turned her ashen face towards the speaker. “Very well done,” she gasped, “and as befitted the descendant of so many Kings”; and with these words she fell dead beside the Queen. The Roman officers, having despatched messengers to inform Octavian of the tragedy, seem to have instituted an immediate inquiry as to the means by which the deaths had taken place. 146 At first the sentries could offer no information, but at length the fact was elicited that a peasant carrying a basket of figs had been allowed to enter the mausoleum, as it was understood that the fruit was for the Queen’s meal. The soldiers declared that they had lifted the leaves with which the fruit was covered and had remarked on the fineness of the figs, whereupon the peasant had laughed and had invited them to take some, which they had refused to do. It was perhaps known that Cleopatra had expressed a preference for death by the bite of an asp, 147 and it was therefore thought that perhaps one of these small snakes had been brought to her concealed under the figs. A search was made for the snake, and one of the soldiers stated that he thought he saw a snake-track leading from the mausoleum over the sand towards the sea. An attendant who had admitted the peasant seems now to have reported that when Cleopatra saw the figs she exclaimed, “So here it is!” a piece of evidence which gave some colour to the theory. Others suggested
- 71. that the asphad been kept at hand for some days in a vase, and that the Queen had, at the end, teased it until she had made it strike at her. An examination of the body showed nothing except two very slight marks upon the arm, which might possibly have been caused by the bite of a snake. On the other hand, it was suggested that the Queen might have carried some form of poison in a hollow hair- comb or other similar article; and this theory must have received some support from the fact that there were the three deaths to account for. Presently Octavian seems to have arrived, and he at once sent for snake-doctors, Psylli, to suck the poison from the wound; but they came too late to save her. Though Octavian expressed his great disappointment at her death, he could not refrain from showing his admiration for the manner in which it had occurred. Personally, he appears to have favoured the theory that her end was caused by the bite of the asp, and afterwards in his Triumph he caused a figure of Cleopatra to be exhibited with a snake about her arm. Though it is thus quite impossible to state with certainty how it occurred, there is no reason to contradict the now generally accepted story of the introduction of the asp in the basket of figs. I have no doubt that the Queen had other poisons in her possession, which were perhaps used by her two faithful women; and it is to be understood that the strategy of the figs, if employed at all, was resorted to only in order that she herself might die by the means which her earlier experiments had commended to her. Octavian now gave orders that the Queen should be buried with full honours beside Antony, where she had wished to lie. He had sent messengers, it would seem, to Berenice to attempt to stop the departure of Cæsarion for India, having heard, no doubt, that the young man had decided to remain in that town until the last possible moment. His tutor, Rhodon, counselled him to trust himself to Octavian; and, acting upon this advice, they returned to Alexandria, where they seem to have arrived very shortly after Cleopatra’s death. Octavian immediately ordered Cæsarion to be executed, his excuse being that it was dangerous for two Cæsars to be in the
- 72. world together; andthus died the last of the Ptolemaic Pharaohs of Egypt, the son and only real heir of the great Julius Cæsar. The two other children who remained in the Palace, Ptolemy and Cleopatra Selene, were shipped off to Rome as soon as possible, and messengers seem to have been despatched to Media to take possession of Alexander Helios who had probably been sent thither, as we have already seen. In my opinion, Octavian now decided to take over Egypt as a kind of personal possession. He did not wish to cause a revolution in the country by proclaiming it a Roman province; and he seems to have appreciated the ceaseless efforts of Cleopatra and her subjects to prevent the absorption of the kingdom in this manner. He therefore decided upon a novel course of action. While not allowing himself to be crowned as actual King of Egypt, he assumed that office by tacit agreement with the Egyptian priesthood. He seems to have claimed, in fact, to be heir to the throne of the Ptolemies. Julius Cæsar had been recognised as Cleopatra’s husband in Egypt, and he, Octavian, was Cæsar’s adopted son and heir. After the elimination of Cleopatra’s three surviving children he was, therefore, the rightful claimant to the Egyptian throne. The Egyptians at once accepted him as their sovereign, and upon the walls of their temples we constantly find his name inscribed in hieroglyphics as “King of Upper and Lower Egypt, Son of the Sun, Cæsar, living for ever, beloved of Ptah and Isis.” He is also called by the title Autocrator, which he took over from Antony, and which, in the Egyptian inscriptions, was recognised as a kind of hereditary royal name, being written within the Pharaonic cartouche. 148 His descendants, the Emperors of Rome, were thus successively Kings of Egypt, as though heads of the reigning dynasty; and each Emperor as he ascended the Roman throne was hailed as Monarch of Egypt, and was called in all Egyptian inscriptions “Pharaoh” and “Son of the Sun.” The Egyptians, therefore, with the acquiescence of Octavian, came to regard themselves not as vassals of Rome, but as subjects of their own King, who happened at the same time to be Emperor of Rome; and thus the great Egypto-Roman Empire for which Cleopatra
- 73. had struggled actuallycame into existence. All Emperors of Rome came to be recognised in Egypt not as sovereigns of a foreign empire of which Egypt was a part, but as actual Pharaohs of Egyptian dominions of which Rome was a part. The ancient dynasties had passed away, the Amenophis and Thutmosis family, the house of Rameses, the line of Psammetichus, and many another had disappeared. And now, in like manner, the house of the Ptolemies had fallen, and the throne of Egypt was occupied by the dynasty of the Cæsars. This dynasty, as it were, supplied Rome with her monarchs; and the fact that Octavian was hailed by Egyptians as King of Egypt long before he was recognised by Romans as Emperor of Rome, gave the latter throne a kind of Pharaonic origin in the eyes of the vain Egyptians. It has usually been supposed that Egypt became a Roman province; but it was never declared to be such. Octavian arranged that it should be governed by a praefectus, who was to act in the manner of a viceroy, 149 and he retained the greater part of the Ptolemaic revenues as his personal property. While later in Rome he pretended that Cleopatra’s kingdom had been annexed, in Egypt it was distinctly understood that the country was still a monarchy. He treated the Queen’s memory with respect, since he was carrying on her line; and he would not allow her statues to be overthrown. 150 All her splendid treasures, however, and the gold and silver plate and ornaments were melted down and converted into money with which to pay the Roman soldiers. The royal lands were seized, the palaces largely stripped of their wealth; and when at last Octavian returned to Rome in the spring of B.C. 29, he had become a fabulously rich man. On August 13th, 14th, and 15th of the same year three great Triumphs were celebrated, the first day being devoted to the European conquests, the second to Actium, and the third to the Egyptian victory. A statue of Cleopatra, the asp clinging to her arm, was dragged through the streets of the capital, and the Queen’s twin
- 74. children, Alexander Heliosand Cleopatra Selene, were made to walk in captivity in the procession. Images representing Nilus and Egypt were carried along, and an enormous quantity of interesting loot was heaped up on the triumphal cars. The poet Propertius tells us how in fancy he saw “the necks of kings bound with golden chains, and the fleet of Actium sailing up the Via Sacra.” All men became unbalanced by enthusiasm, and stories derogatory to Cleopatra were spread on all sides. Horace, in a wonderful ode, expressed the public sentiments, and denounced the unfortunate Queen as an enemy of Rome. Honours were heaped upon Octavian; and soon afterwards he was given the title of Augustus, and was named Divi filius, as being heir of Divus Julius. He took great delight in lauding the memory of the great Dictator, who was now accepted as one of the gods of the Roman world; and it is a significant fact that he revived and reorganised the Lupercalia, as though he were in some manner honouring Cæsar thereby. 151 Meanwhile the three children of Cleopatra and Antony found a generous refuge in the house of Octavia, Antony’s discarded wife. With admirable tact Octavian seems to have insisted upon this solution of the difficulty as to what to do with them. Their execution would have been deeply resented by the Egyptians, and, since Octavian was now posing as the legal heir to the throne of Egypt, the dynastic successor of Cleopatra, and not a foreign usurper, it was well that his own sister should look after these members of the royal family. Octavia, always meek and dutiful, accepted the arrangement nobly, and was probably unvaryingly kind to these children of her faithless husband, whom she brought up with her two daughters, Antonia Major and Minor, and Julius Antonius, the second son of Antony and Fulvia, and brother of the murdered Antyllus. When the little Cleopatra Selene grew up she was married to Juba, the King of Numidia, a learned and scholarly monarch, who was later made King of Mauretania. The son of this marriage was named Ptolemy, and succeeded his father about A.D. 19. He was murdered by Caligula, who, by the strange workings of Fate, was also a descendant of Antony. We do not know what became of Alexander Helios and his
- 75. brother Ptolemy. Tacitustells us 152 that Antonius Felix, Procurator of Judæa under the Emperor Nero, married (as his second wife) Drusilla, a granddaughter of Cleopatra and Antony, who was probably another of the Mauretanian family. Octavia died in B.C. 11. Antony’s son, Julius Antonius, in B.C. 2, was put to death for his immoral relations with Octavian’s own daughter Julia, she herself being banished to the barren island of Pandateria. Octavian himself, covered with honours and full of years, died in A.D. 14, being succeeded upon the thrones of Egypt and of Rome by Tiberius, his son. During the latter part of the reign of Octavian, or Augustus, as one must call him, the influence of Alexandria upon the life of Rome began to be felt in an astonishing degree; and so greatly did Egyptian thought alter the conditions in the capital that it might well be fancied that the spirit of the dead Cleopatra was presiding over that throne which she had striven to ascend. Ferrero goes so far as to suggest that the main ideas of splendid monarchic government and sumptuous Oriental refinement which now developed in Rome were due to the direct influence of Alexandria, and perhaps to the fact that the new emperors were primarily Kings of Egypt. Alexandrian artists and artisans swarmed over the sea to Italy, and the hundreds of Romans who had snatched estates for themselves in Egypt travelled frequently to that country on business, and unconsciously familiarised themselves with its arts and crafts. Alexandrian sculpture and painting was seen in every villa, and the poetry and literature of the Alexandrian school were read by all fashionable persons. Every Roman wanted to employ Alexandrians to decorate his house, everybody studied the manners and refinements of the Græco-Egyptians. The old austerity went to pieces before the buoyancy of Cleopatra’s subjects, just as the aloofness of London has disappeared under the Continental invasion of the last few years. Thus it may be said that the Egypto-Roman Empire of Cleopatra’s dreams came to be founded in actual fact, with this
- 76. difference, that itsmonarchs were sprung from the line of Octavian, Cæsar’s nephew, and not from that of Cæsarion, Cæsar’s son. But while Egypt and Alexandria thus played such an important part in the creation of the Roman monarchy, the memory of Cleopatra, from whose brain and whose influence the new life had proceeded, was yearly more painfully vilified. She came to be the enemy of this Orientalised Rome, which still thought itself Occidental; and her struggle with Octavian was remembered as the evil crisis through which the party of the Cæsars had passed. Abuse was heaped upon her, and stories were invented in regard to her licentious habits. It is upon this insecure basis that the world’s estimate of the character of Cleopatra is founded; and it is necessary for every student of these times at the outset of his studies to rid his mind of the impression which he will have obtained from these polluted sources. Having shut out from his memory the stinging words of Propertius and the fierce lines of Horace, written in the excess of his joy at the close of the period of warfare which had endangered his little country estate, the reader will be in a position to judge whether the interpretation of Cleopatra’s character and actions, which I have laid before him, is to be considered as unduly lenient, and whether I have made unfair use of the merciful prerogative of the historian, in behalf of an often lonely and sorely tried woman, who fought all her life for the fulfilment of a patriotic and splendid ambition, and who died in a manner “befitting the descendant of so many kings.” THE END. PRINTED BY WILLIAM BLACKWOOD AND SONS.
- 77. GENEALOGY OF THEPTOLEMIES.
- 79. LAGOS. | +--------+ | FIRST HUSBAND. =BERENICE I., = PTOLEMY I., | grandniece | Soter I., | of Antipater | a General of | of Macedon. | Alexander the | | Great, afterwards | | King of Egypt. | | +----------------+ +-------+-----+ | | | MAGAS, = APAMA ARSINOE II., = PTOLEMY II., = ARSINOE I., King | of second wife Philadelphus, | first wife, of | Syria. and sister, King of Egypt. | daughter of Cyrene. | first | Lysimachos, | married to | King of | Lysimachos, | Thrace. | King of Thrace. | | | +---------------+ +-------------+ | | BERENICE II. = PTOLEMY III., | Euergetes I., | King of Egypt. | +---------+-------+-------------------+ | | | ANTIOCHOS PTOLEMY IV., = ARSINOE III. MAGAS. the Great, Philopator, | King of King of Egypt. | Syria. | | | +-----+ +-------------+ | | CLEOPATRA I. = PTOLEMY V., | Epiphanes, | King of Egypt. | +-----+------------------+----------------+--------+ | | | | PTOLEMY VI., PTOLEMY VII. = CLEOPATRA II. | Eupator, Philometor, | | King of Egypt. King of Egypt. | | | | | | +----------------------------+--------+ |
- 80. | | | | PTOLEMYVIII., CLEOPATRA III. = PTOLEMY IX., | Neos Philopator, | Euergetes II., | King of Egypt. | King of Egypt. | | | +----------------+----------------+-----+ | | | | | N.N. = PTOLEMY X., = CLEOPATRA IV. SELENE. | Soter II., | | King of Egypt. | | | | +------------+-+----------------+--------+ | | | | | | CLEOPATRA V. = PTOLEMY XIII., = N.N. | BERENICE III. = PTOLEMY XI., | Neos Dionysos, | | | Alexander I., | “Auletes.” | | | King of Egypt. | | | | | | PTOLEMY, | | | King of | | | Cyprus. | | | PTOLEMY XII., | | Alexander II., | | King of Egypt. +-------+-------+ +-------+ | | | CLEOPATRA VI. BERENICE IV., | married Archelaus, | High Priest of | Komana. | | +-----------+-------+--------------+----------+ | | | | PTOLEMY XV., | ARSINOE IV. JULIUS = CLEOPATRA VII. = MARCUS King of Egypt. | CÆSAR. | | ANTONIUS. | | | PTOLEMY XIV., | | King of Egypt. | | CÆSARION, | Ptolemy XVI., | King of Egypt. | | +-----------------------+--------------------+-----+ | | | ALEXANDER HELIOS, CLEOPATRA = JUBA, PTOLEMY. married Iotapa SELENE. | King of of Media. | Mauretania. | +-----------+-------+ | ?| PTOLEMY DRUSILLA = ANTONIUS FELIX
- 81. PTOLEMY, DRUSILLA. =ANTONIUS FELIX, King of | Procurator of Mauretania. | Judæa. | ^
- 82. FOOTNOTES 1 Dickens. 2 Sergeant. 3 The Egyptian reliefsupon the walls of Dendereh temple and elsewhere show conventional representations of the Queen which are not to be regarded as real portraits. The so-called head of the Queen in the Alexandria Museum probably does not represent her at all, as most archæologists will readily admit. 4 This island has now become part of the mainland. 5 For a restoration of the lighthouse, see the work of H. Thiersch. 6 Josephus. 7 The first Ptolemy brought the body of Alexander to Alexandria, and deposited it, so it is said, in a golden sarcophagus; but this was believed to have been stolen, and the alabaster one substituted. 8 Surely not 200 feet, as is sometimes said. 9 Some years later, after it had been popularised by Augustus.
- 83. 10 Plutarch: Cæsar. 11 Bell. Civ.III. 47. 12 Susemihl. Geschichte der griechischen Litteratur in der Alexandrinerzeit. 13 In hieroglyphs the name reads Kleopadra. It is a Greek name, meaning “Glory of her Race.” 14 Representations of Cleopatra or other sovereigns of the dynasty dressed in Egyptian costume are probably simply traditional. 15 Mommsen. 16 Or do I wrong the hero of Utica? 17 Porphyry says he died in the eighth year of Cleopatra’s reign, and Josephus states that he was fifteen years of age at his death. This would make him about seven years old at Cleopatra’s accession, which seems probable enough. 18 He had been Consul with Julius Cæsar in 59. 19 The end of September, owing to irregularities in the calendar, of which we shall presently hear more, corresponded to the middle of July. 20 According to Plutarch and others; but the incident is not mentioned in Cæsar’s memoirs. 21 I do not know any record of what became of the 2000 men of Pompey’s bodyguard. They probably fled back to Europe on the death of their commanding officer.
- 84. 22 As Consul hewould have been entitled to twelve lictors, as Dictator to twenty-four; but we are not told which number he employed on this occasion. 23 I quote the telling phrase used by Warde Fowler in his ‘Social Life at Rome.’ 24 In interpreting the situation thus, I am aware that I place myself at variance with the accepted view which attributes to Cæsar an eagerness to return quickly to Rome. 25 It is not certain whether the 2000 horse are to be included or not in the total of 20,000. 26 In spite of the statement to the contrary in De Bello Alexandrino. 27 So the early writers state. 28 Page 235. 29 It is usually stated that Cæsar remained in Egypt chiefly because he was in need of money, as is suggested by Dion, xlii. 9 and 34; Oros, vi. 15, 29, and Plutarch, 48. But the small sum which he took from the Egyptians is against this theory. 30 In ancient Egypt the princes and princesses often had male “nurses,” the title being an exceedingly honourable one. The Egyptian phrase sometimes reads “great nurse and nourisher,” and M. Lefebvre tells me that in a Fayoum inscription the tutor of Ptolemy Alexander is called τροφεὺς καὶ τιθηνὸς Ἀλεξάνδρου. 31 Plutarch.
- 85. 32 See p. 31. 33 Notealso (p. 112) Cæsar’s departure with his army from the besieged Palace. 34 This was actually some time in January. 35 Just as the British Army of Occupation now in Egypt was originally stationed there to support the Khedive upon his throne and to keep order. 36 Corresponding to the actual season of February. 37 Pliny, vi. 26. 38 Pliny, vi. 26. 39 Page 57. 40 It has generally been stated that Cæsar left Egypt before the birth of Cæsarion, an opinion which, in view of the fact that Appian says he remained nine months in Egypt, has always seemed to me improbable; for it is surely more than a coincidence that he delayed his departure from Egypt until the very month in which Cleopatra’s and his child was to be expected to arrive, he having met her in the previous October. Plutarch’s statement may be interpreted as meaning that Cæsar departed to Syria after the birth of his son. I think that Cicero’s remark, in a letter dated in June B.C. 47, that there was a serious hindrance to Cæsar’s departure from Alexandria, refers to the event for which he was waiting. Those who suggest that Cæsar did not remain in Egypt so long are obliged to deny that the authors are correct in stating that he went up the Nile; and they have to disregard the positive statement of Appian that the Dictator’s visit lasted nine months. Moreover, the
- 86. Welcome to ourwebsite – the ideal destination for book lovers and knowledge seekers. With a mission to inspire endlessly, we offer a vast collection of books, ranging from classic literary works to specialized publications, self-development books, and children's literature. Each book is a new journey of discovery, expanding knowledge and enriching the soul of the reade Our website is not just a platform for buying books, but a bridge connecting readers to the timeless values of culture and wisdom. With an elegant, user-friendly interface and an intelligent search system, we are committed to providing a quick and convenient shopping experience. Additionally, our special promotions and home delivery services ensure that you save time and fully enjoy the joy of reading. Let us accompany you on the journey of exploring knowledge and personal growth! ebookultra.com