The document discusses wireless and mobile networks. It notes that the number of wireless phone subscribers now exceeds wired phone subscribers, and more devices are gaining wireless Internet access. There are two main challenges for wireless networks: communicating over wireless links, and handling users that change their point of connection to the network as they move. The chapter outlines topics like wireless link characteristics, cellular network architecture and standards, addressing and routing for mobile users, and how mobility is handled in different network types. It also describes elements of wireless networks like wireless hosts, base stations, and infrastructure for connecting mobiles to wired networks.
This document discusses wireless and mobile networks. It begins with an introduction to wireless networks and mobility challenges. It then summarizes key standards and technologies for wireless links including characteristics of wireless links, CDMA, IEEE 802.11 wireless LANs, and cellular networks. It outlines addressing and routing challenges for mobile users. Finally, it discusses how mobility is handled in different network types and at higher layers of the network stack.
In enterprises today, Wide Area Networks (WANs) are no
longer operating behind the scenes. WANs are central to
the daily operations and core business of organizations large
and small. However, enterprises must choose from a variety
of ways to implement WANs. This eBook examines the
various types of Wide Area Networks (WANs), and why
IT departments gravitate towards specific WAN solutions.
In addition, the paper provides constructive guidelines
for organizations seeking Local Area to Wide Area
Network extension.
This document summarizes a study that designed an integrated WiFi/WiMAX network using the QUALNET simulator. WiFi provides high data rates but short range, while WiMAX has lower data rates but much longer range. The study developed a coupler device that can receive WiMAX signals and convert them to WiFi, allowing seamless connectivity across both networks. This provides continuous coverage for users in high-rise buildings that may be outside WiFi range. The integrated network was analyzed in QUALNET and was found to provide high throughput, low delay, and consistent performance.
The document discusses wide area networks (WAN) and key concepts:
1) A WAN extends the reach of a network beyond a local area and uses shared transmission services from a provider.
2) WAN technologies operate at the physical layer (connections) and data link layer (encapsulation). Common options include leased lines, frame relay, ATM, and broadband technologies.
3) Factors in selecting a WAN include performance needs, connectivity, availability, and cost.
EFFICIENT REAL-TIME VIDEO TRANSMISSION IN WIRELESS MESH NETWORK IJORCS
This document summarizes a research paper on efficient real-time video transmission in wireless mesh networks. It begins with an introduction to wireless mesh networks and their benefits. It then discusses some key challenges for real-time video transmission, including unpredictable delays, packet loss, and delay jitter due to the error-prone nature of wireless links. The paper proposes a model to provide high-capacity data transfer with reduced delay for real-time video. It simulates this model using OPNET and achieves higher throughput results. Node models for the video server, receiver, access point, and FTP client/server are also described.
IEEE 802.16 is a standard for fixed wireless broadband access that provides high-speed internet access over long distances (up to 31 miles). It uses point-to-multipoint radio links to connect base stations to multiple subscriber stations and supports services like data, voice, and video. The standard defines the physical and medium access control layers for both licensed and unlicensed frequency bands below 11GHz to support residential and small business broadband connectivity as a cheaper alternative to fiber.
Future Technologies and Testing for Fixed Mobile Convergence,SAE and LTE in C...Going LTE
This white paper discusses future technologies for fixed-mobile convergence including LTE and SAE. It defines fixed-mobile convergence as providing consistent services via any fixed or mobile access point. The paper describes the motivation for convergence including mobility and consistent services. It outlines the LTE/SAE introduction and technologies including the evolved packet core and all-IP architecture. Key aspects of LTE such as physical layer channels and protocols are also summarized. The purpose is to support an integrated network through the IP Multimedia Subsystem for high-speed mobile experiences comparable to fixed broadband.
The document discusses wireless local area networks (WLANs) and the mobile internet. It describes the IEEE 802.11 communication protocol used in WLANs and the development of WiFi. It also discusses wireless network configurations including independent basic service sets, distributed systems, and extended service sets. The layers of the IEEE 802.11 protocol are described along with the Wireless Application Protocol used for wireless internet access.
This document discusses wireless and mobile networks. It begins with an introduction to wireless networks and mobility challenges. It then summarizes key standards and technologies for wireless links including characteristics of wireless links, CDMA, IEEE 802.11 wireless LANs, and cellular networks. It outlines addressing and routing challenges for mobile users. Finally, it discusses how mobility is handled in different network types and at higher layers of the network stack.
In enterprises today, Wide Area Networks (WANs) are no
longer operating behind the scenes. WANs are central to
the daily operations and core business of organizations large
and small. However, enterprises must choose from a variety
of ways to implement WANs. This eBook examines the
various types of Wide Area Networks (WANs), and why
IT departments gravitate towards specific WAN solutions.
In addition, the paper provides constructive guidelines
for organizations seeking Local Area to Wide Area
Network extension.
This document summarizes a study that designed an integrated WiFi/WiMAX network using the QUALNET simulator. WiFi provides high data rates but short range, while WiMAX has lower data rates but much longer range. The study developed a coupler device that can receive WiMAX signals and convert them to WiFi, allowing seamless connectivity across both networks. This provides continuous coverage for users in high-rise buildings that may be outside WiFi range. The integrated network was analyzed in QUALNET and was found to provide high throughput, low delay, and consistent performance.
The document discusses wide area networks (WAN) and key concepts:
1) A WAN extends the reach of a network beyond a local area and uses shared transmission services from a provider.
2) WAN technologies operate at the physical layer (connections) and data link layer (encapsulation). Common options include leased lines, frame relay, ATM, and broadband technologies.
3) Factors in selecting a WAN include performance needs, connectivity, availability, and cost.
EFFICIENT REAL-TIME VIDEO TRANSMISSION IN WIRELESS MESH NETWORK IJORCS
This document summarizes a research paper on efficient real-time video transmission in wireless mesh networks. It begins with an introduction to wireless mesh networks and their benefits. It then discusses some key challenges for real-time video transmission, including unpredictable delays, packet loss, and delay jitter due to the error-prone nature of wireless links. The paper proposes a model to provide high-capacity data transfer with reduced delay for real-time video. It simulates this model using OPNET and achieves higher throughput results. Node models for the video server, receiver, access point, and FTP client/server are also described.
IEEE 802.16 is a standard for fixed wireless broadband access that provides high-speed internet access over long distances (up to 31 miles). It uses point-to-multipoint radio links to connect base stations to multiple subscriber stations and supports services like data, voice, and video. The standard defines the physical and medium access control layers for both licensed and unlicensed frequency bands below 11GHz to support residential and small business broadband connectivity as a cheaper alternative to fiber.
Future Technologies and Testing for Fixed Mobile Convergence,SAE and LTE in C...Going LTE
This white paper discusses future technologies for fixed-mobile convergence including LTE and SAE. It defines fixed-mobile convergence as providing consistent services via any fixed or mobile access point. The paper describes the motivation for convergence including mobility and consistent services. It outlines the LTE/SAE introduction and technologies including the evolved packet core and all-IP architecture. Key aspects of LTE such as physical layer channels and protocols are also summarized. The purpose is to support an integrated network through the IP Multimedia Subsystem for high-speed mobile experiences comparable to fixed broadband.
The document discusses wireless local area networks (WLANs) and the mobile internet. It describes the IEEE 802.11 communication protocol used in WLANs and the development of WiFi. It also discusses wireless network configurations including independent basic service sets, distributed systems, and extended service sets. The layers of the IEEE 802.11 protocol are described along with the Wireless Application Protocol used for wireless internet access.
Implementation of Vertical Handoff Algorithm between IEEE 802.11 WLAN & CDMA ...IOSR Journals
Wireless communications is the fastest growing segment of the communications industry. Everyone
wants the quality of services anytime & anywhere. Wireless networks can integrate various heterogeneous radio
access technologies as GSM, WLAN, Wimax etc. WiMAX is an IP based, wireless broadband access technology
that provides performance similar to 802.11/Wi-Fi networks with the coverage and QOS (quality of service) of
cellular networks. WiMAX is also an acronym meaning "Worldwide Interoperability for Microwave Access
(WiMAX). The main promise of interconnecting these heterogeneous networks is to provide high performance in
achieving a high data rate and support real time applications. These services require various networks (such as
CDMA2000 and Wireless LAN) to be integrated into IP-based networks, which further require a seamless
vertical handoff to 4th generation wireless networks. When a mobile host (MH) changes its point of attachment,
its IP address gets changed. MH should be able to maintain all the existing connections using the new IP
address. This process of changing a connection from one IP address to another one in IP network is called
handoff. Vertical handoff is switching from one network to another while maintaining the session. Vertical
Handoff (VHO) is a major concern for different heterogeneous networks. VHO can be user requested or based
on some criteria already designed by the researcher of that particular algorithm. The main objective is to
implement efficient & effective handoff scheme between two heterogeneous network ie. 802.11 WLAN &
CDMA
AN ADAPTIVE DIFFSERV APPROACH TO SUPPORT QOS IN NETWORK MOBILITY NEMO ENVIRON...IJCNCJournal
Network Mobility Basic Support (NEMO BS) protocol (RFC 3963) is an extension of Mobile IPv6. The NEMO BS embraced by IETF working group to permit any node in the portable network to be accessible to the Internet despite the fact the network itself is roaming. This protocol likewise Mobile IPv6 doesn’t deliver any kind of Quality of Service (QoS) guarantees to its clients. It can barely offer the same level of services (i.e. Best-Effort) to all the users without obligation to the application’s needs. This propositions a challenge to real-time applications that demand a precise level of QoS pledge. The Differentiated Services has recently come to be the most widely used QoS support technology in IP networks due to its relative simplicity and scalability benefits. This paper proposes a new scheme to provide QoS to mobile network nodes within NEMO context. The proposed scheme intends to reduce handover latency for the users of MNN as well as alleviates packet losses. The feasibility of the proposed enhancement is assessed by measuring its performance against the native NEMO BS standard protocol using NS-2 simulator. The obtained results in the simulation study have demonstrated that the proposed scheme outperforms the standard NEMO BS protocol.
This document summarizes a research paper that proposes a quality of service (QoS) oriented vertical handoff scheme for interworking between wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) networks.
The paper first provides background on WLAN and WiMAX network architectures. It then reviews existing vertical handoff approaches and identifies limitations such as considering too many decision parameters that increase handoff delay. The proposed scheme measures traffic and available bandwidth in both networks. It uses these metrics and a handoff policy to make handoff decisions via a handoff decision module, aiming to improve QoS in terms of throughput. Algorithms are also described to estimate available bandwidth in WLAN and Wi
Quantative Analysis and Evaluation of Topology Control Schemes for Utilizing ...ijsrd.com
By virtue of their robustness, cost-effectiveness, self-organizing and self-configuring nature, WMNs have emerged as a new network paradigm for a wide range of applications, such as public safety and emergency response communications, intelligent transportation systems, and community networks. It is anticipated that WMNs will not only resolve the limitations of wireless ad hoc networks, local area networks (WLANs), personal area networks (WPANs), and metropolitan area networks (WMANs) but also significantly improve such networks’ performance. One fundamental problem of WMNs with a limited number of radio interfaces and orthogonal channels is that the performance degrades significantly as the network size grows. This results from increased interference between nodes and diminished spatial reuse over the network. In this paper, it is proposed to evaluate the performance of two different channel assignment schemes namely common channel assignment (CCA) and centralized tabu-based search algorithm under WCETT routing protocols for varying traffic load in terms of packet delivery ratio, throughput, average end to end delay and routing overhead using NS2 network simulator. WCETT protocol uses the weighted sum of the cumulative expected transmission time and the maximal value of efficient channels among all channels.
This document provides an overview of Network Mobility (NEMO), which allows entire networks of devices to maintain internet connectivity as the network changes its point of attachment. It describes how NEMO works by having a mobile router perform mobility functions on behalf of attached nodes in a manner transparent to them. Applications of NEMO could include providing internet access to passengers on planes and in cars, as well as across personal area networks. Key aspects of NEMO standards and protocols are also outlined.
The DEUS project aims to develop an easy to deploy and use versatile wireless network infrastructure for dynamic environments. It identifies four network domains: a wireless backbone, wireless sensor networks, access points, and backend servers. The backbone mesh provides a secure, self-organizing transport network between components. Wireless sensor networks share features with the mesh but support multiple routing protocols. Global routing optimizes paths between sensors and connects different network domains in a transparent way. Access points deployed on the mesh provide seamless client mobility. The architectural concept forms the basis for DEUS proof of concept implementations across different use cases.
This document analyzes the performance of different VoIP codecs over a WiMAX network using the network simulator NS2. The simulation varies parameters like the number of nodes and type of VoIP codec. Performance is evaluated based on metrics like throughput, average delay, and jitter. Results are presented graphically to compare these metrics for different codecs and number of nodes. The document provides background on VoIP codecs, IEEE 802.16 service flow classes, and simulation setup using NS2.
Heterogeneous networks use a mix of different cellular technologies and base station types to improve network capacity and coverage, especially in crowded areas. This includes macro base stations covering large areas, indoor pico base stations handling 70% of traffic, and micro and small cells to further improve coverage. By 2020, there will be over 50 billion connected devices relying on networks employing heterogeneous strategies to optimize the mobile experience.
Modem = modulator + demodulator.
A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves.
SIP-Based Mobility Management for LTE-WiMAX-WLAN Interworking Using IMS Archi...CSCJournals
In this paper, we propose an architecture framework for interworking of Long Term Evolution (LTE), Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) technologies. The aim is to offer users of various networks seamless high quality IP-based multimedia services access anywhere at any time. IP Multimedia Subsystem (IMS) is used in the proposed architecture for providing a platform through which telecommunications operators can merge the various networks. A Session Initiation Protocol (SIP) REFER method which provides uninterrupted service continuity is introduced. The proposed LTE-WiMAX and LTE-WLAN tight coupled interworking is compared with the UMTS- WiMAX and UMTS-WLAN tight coupled interworking. The two heterogeneous networks are simulated using OPNET Modeler 17.1. Various metrics are obtained to test the performance of the proposed technique. Results show that successful VoIP session handoffs with acceptable Quality of Services (QoS) levels can be performed. Results also show that the proposed architecture outperforms the pervious architecture.
The document provides information on the history and technology of BSNL, the Indian state-run telecommunications company. It was formed in 1985 when the Department of Post and Telegraph was separated into the Department of Post and Department of Telegraph. The document then describes how a telephone subscriber is connected to an exchange, going through the handset, rosette, window, distribution point, and main distribution frame. It also provides brief summaries of WiMAX technology and applications, broadband policy and subscribers in India, and optical fiber and GSM network architecture.
This document discusses handover management in integrated WLAN and WiMAX networks using the IEEE 802.21 Media Independent Handover (MIH) framework. It describes the need for integration of heterogeneous wireless networks to provide ubiquitous coverage and broadband connectivity. It explains homogeneous and heterogeneous handovers and the role of IEEE 802.21 in facilitating handovers across different network types. The MIH framework provides services and events to support handovers between WiFi and WiMAX networks in a seamless manner for mixed network clients.
Latest technologies used to transfer data using internetSaqlain Memon
this are the latest technologies used to transfer data in internet using this you can transfer data very easily be smart on the internet be protective in india for more information log in to saqlainmemon776@gmail.com find interesting things on this
Wireless networks allow devices to connect to a network without being physically connected with wires. They consist of wireless hosts that communicate over the air with network infrastructure like access points or base stations. There are challenges to wireless communication including signal attenuation, interference, and the hidden terminal problem. Wireless networks can operate in infrastructure mode with access points or in ad hoc mode without infrastructure between devices. Standards like 802.11 (Wi-Fi) and CDMA are used to allow multiple devices to communicate over the same wireless channel. Devices must associate with an access point to connect to the network and protocols like CSMA/CA are used to avoid collisions between transmissions.
This document analyzes the performance of Wi-Fi networks under three conditions: no fading, flat fading, and dispersive fading. It simulates these conditions using an IEEE 802.11a WLAN physical layer model in Matlab. The simulation measures packet error rate and bit rate as the signal-to-noise ratio and maximum Doppler shift are varied. With no fading, there is no packet error and bit rate increases with SNR. Under flat and dispersive fading, packet error and bit rates are affected differently based on the maximum Doppler shift. The best performance occurs under flat fading with a lower maximum Doppler shift of 100Hz.
Survey of Routing Scheme in MANET with Clustering TechniquesIJMER
This document provides an overview of routing schemes and clustering techniques in mobile ad hoc networks (MANETs). It discusses different routing protocols for MANETs including proactive, reactive, and hybrid protocols. Examples of proactive protocols mentioned are OLSR and DSDV, while reactive protocols include AODV and DSR. Hybrid protocols combine aspects of proactive and reactive routing, with examples being ZRP and CBRP. The document also surveys various clustering approaches for MANETs including location-based, neighbor-based, power-based, and mobility-based techniques. It analyzes the advantages and disadvantages of different routing protocols and clustering methods.
The document discusses du's broadband portfolio in the UAE, with a case study on implementing WiFi on the Dubai Metro. It outlines du's use of HSPA, WiMAX, and WiFi technologies for mobile and fixed broadband services. Specifically, du used WiMAX to provide the backhaul network for Metro WiFi access on trains and in stations. While HSPA has a smaller cell radius that shrinks with loading, WiMAX provides consistent coverage and can support more users at the cell edge achieving 512kbps throughput. Overall, WiMAX networks have higher capacity and lower latency than comparable HSPA networks.
This document discusses speed adaptive mobile IP over wireless LAN. It first analyzes the relationship between performance and moving speed for mobile IP over wireless LAN, showing that current mobile IP is not suitable for rapid movement. It then proposes a speed adaptive mobile IP protocol that extends registration messages with speed information to allow the network behavior to automatically adapt based on node speed, improving performance for rapid movement without high resource costs. The protocol is emulated and shown to greatly improve mobile IP performance for rapid movement over wireless LAN.
Introductory Approach on Ad-hoc Networks and its Paradigms IJORCS
This document provides an introductory overview of ad-hoc networks, including:
1) A definition of ad-hoc networks as decentralized wireless networks that self-configure without preexisting infrastructure;
2) A discussion of mobile ad-hoc networks (MANETs) and wireless sensor networks as examples of ad-hoc networks;
3) An overview of challenges in providing quality of service in ad-hoc networks given their dynamic topology.
This document provides an overview of key topics in chapter 6 on wireless and mobile networks. It begins with background on the growth of wireless networks and defines two main challenges - wireless communication over the wireless link, and handling mobility as users change their point of attachment. The chapter outline is then presented, covering wireless link characteristics, IEEE 802.11 wireless LANs, cellular networks, principles of addressing and routing for mobile users, and handling mobility. Elements of wireless networks like wireless hosts, base stations, and wireless links are defined. Characteristics of different wireless links are summarized and issues like interference, multipath propagation, and the hidden terminal problem are introduced.
This document provides an overview of wireless and mobile networks. It begins with background on the growth of wireless networks and devices. The key challenges of wireless communication over wireless links and handling mobility are introduced. The chapter outline covers wireless link characteristics, wireless local area networks (Wi-Fi), cellular networks, and principles of mobility. Elements of wireless networks like base stations, wireless hosts, and infrastructure and ad hoc modes are defined. Characteristics of different wireless links and issues like interference are also summarized.
Implementation of Vertical Handoff Algorithm between IEEE 802.11 WLAN & CDMA ...IOSR Journals
Wireless communications is the fastest growing segment of the communications industry. Everyone
wants the quality of services anytime & anywhere. Wireless networks can integrate various heterogeneous radio
access technologies as GSM, WLAN, Wimax etc. WiMAX is an IP based, wireless broadband access technology
that provides performance similar to 802.11/Wi-Fi networks with the coverage and QOS (quality of service) of
cellular networks. WiMAX is also an acronym meaning "Worldwide Interoperability for Microwave Access
(WiMAX). The main promise of interconnecting these heterogeneous networks is to provide high performance in
achieving a high data rate and support real time applications. These services require various networks (such as
CDMA2000 and Wireless LAN) to be integrated into IP-based networks, which further require a seamless
vertical handoff to 4th generation wireless networks. When a mobile host (MH) changes its point of attachment,
its IP address gets changed. MH should be able to maintain all the existing connections using the new IP
address. This process of changing a connection from one IP address to another one in IP network is called
handoff. Vertical handoff is switching from one network to another while maintaining the session. Vertical
Handoff (VHO) is a major concern for different heterogeneous networks. VHO can be user requested or based
on some criteria already designed by the researcher of that particular algorithm. The main objective is to
implement efficient & effective handoff scheme between two heterogeneous network ie. 802.11 WLAN &
CDMA
AN ADAPTIVE DIFFSERV APPROACH TO SUPPORT QOS IN NETWORK MOBILITY NEMO ENVIRON...IJCNCJournal
Network Mobility Basic Support (NEMO BS) protocol (RFC 3963) is an extension of Mobile IPv6. The NEMO BS embraced by IETF working group to permit any node in the portable network to be accessible to the Internet despite the fact the network itself is roaming. This protocol likewise Mobile IPv6 doesn’t deliver any kind of Quality of Service (QoS) guarantees to its clients. It can barely offer the same level of services (i.e. Best-Effort) to all the users without obligation to the application’s needs. This propositions a challenge to real-time applications that demand a precise level of QoS pledge. The Differentiated Services has recently come to be the most widely used QoS support technology in IP networks due to its relative simplicity and scalability benefits. This paper proposes a new scheme to provide QoS to mobile network nodes within NEMO context. The proposed scheme intends to reduce handover latency for the users of MNN as well as alleviates packet losses. The feasibility of the proposed enhancement is assessed by measuring its performance against the native NEMO BS standard protocol using NS-2 simulator. The obtained results in the simulation study have demonstrated that the proposed scheme outperforms the standard NEMO BS protocol.
This document summarizes a research paper that proposes a quality of service (QoS) oriented vertical handoff scheme for interworking between wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) networks.
The paper first provides background on WLAN and WiMAX network architectures. It then reviews existing vertical handoff approaches and identifies limitations such as considering too many decision parameters that increase handoff delay. The proposed scheme measures traffic and available bandwidth in both networks. It uses these metrics and a handoff policy to make handoff decisions via a handoff decision module, aiming to improve QoS in terms of throughput. Algorithms are also described to estimate available bandwidth in WLAN and Wi
Quantative Analysis and Evaluation of Topology Control Schemes for Utilizing ...ijsrd.com
By virtue of their robustness, cost-effectiveness, self-organizing and self-configuring nature, WMNs have emerged as a new network paradigm for a wide range of applications, such as public safety and emergency response communications, intelligent transportation systems, and community networks. It is anticipated that WMNs will not only resolve the limitations of wireless ad hoc networks, local area networks (WLANs), personal area networks (WPANs), and metropolitan area networks (WMANs) but also significantly improve such networks’ performance. One fundamental problem of WMNs with a limited number of radio interfaces and orthogonal channels is that the performance degrades significantly as the network size grows. This results from increased interference between nodes and diminished spatial reuse over the network. In this paper, it is proposed to evaluate the performance of two different channel assignment schemes namely common channel assignment (CCA) and centralized tabu-based search algorithm under WCETT routing protocols for varying traffic load in terms of packet delivery ratio, throughput, average end to end delay and routing overhead using NS2 network simulator. WCETT protocol uses the weighted sum of the cumulative expected transmission time and the maximal value of efficient channels among all channels.
This document provides an overview of Network Mobility (NEMO), which allows entire networks of devices to maintain internet connectivity as the network changes its point of attachment. It describes how NEMO works by having a mobile router perform mobility functions on behalf of attached nodes in a manner transparent to them. Applications of NEMO could include providing internet access to passengers on planes and in cars, as well as across personal area networks. Key aspects of NEMO standards and protocols are also outlined.
The DEUS project aims to develop an easy to deploy and use versatile wireless network infrastructure for dynamic environments. It identifies four network domains: a wireless backbone, wireless sensor networks, access points, and backend servers. The backbone mesh provides a secure, self-organizing transport network between components. Wireless sensor networks share features with the mesh but support multiple routing protocols. Global routing optimizes paths between sensors and connects different network domains in a transparent way. Access points deployed on the mesh provide seamless client mobility. The architectural concept forms the basis for DEUS proof of concept implementations across different use cases.
This document analyzes the performance of different VoIP codecs over a WiMAX network using the network simulator NS2. The simulation varies parameters like the number of nodes and type of VoIP codec. Performance is evaluated based on metrics like throughput, average delay, and jitter. Results are presented graphically to compare these metrics for different codecs and number of nodes. The document provides background on VoIP codecs, IEEE 802.16 service flow classes, and simulation setup using NS2.
Heterogeneous networks use a mix of different cellular technologies and base station types to improve network capacity and coverage, especially in crowded areas. This includes macro base stations covering large areas, indoor pico base stations handling 70% of traffic, and micro and small cells to further improve coverage. By 2020, there will be over 50 billion connected devices relying on networks employing heterogeneous strategies to optimize the mobile experience.
Modem = modulator + demodulator.
A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves.
SIP-Based Mobility Management for LTE-WiMAX-WLAN Interworking Using IMS Archi...CSCJournals
In this paper, we propose an architecture framework for interworking of Long Term Evolution (LTE), Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) technologies. The aim is to offer users of various networks seamless high quality IP-based multimedia services access anywhere at any time. IP Multimedia Subsystem (IMS) is used in the proposed architecture for providing a platform through which telecommunications operators can merge the various networks. A Session Initiation Protocol (SIP) REFER method which provides uninterrupted service continuity is introduced. The proposed LTE-WiMAX and LTE-WLAN tight coupled interworking is compared with the UMTS- WiMAX and UMTS-WLAN tight coupled interworking. The two heterogeneous networks are simulated using OPNET Modeler 17.1. Various metrics are obtained to test the performance of the proposed technique. Results show that successful VoIP session handoffs with acceptable Quality of Services (QoS) levels can be performed. Results also show that the proposed architecture outperforms the pervious architecture.
The document provides information on the history and technology of BSNL, the Indian state-run telecommunications company. It was formed in 1985 when the Department of Post and Telegraph was separated into the Department of Post and Department of Telegraph. The document then describes how a telephone subscriber is connected to an exchange, going through the handset, rosette, window, distribution point, and main distribution frame. It also provides brief summaries of WiMAX technology and applications, broadband policy and subscribers in India, and optical fiber and GSM network architecture.
This document discusses handover management in integrated WLAN and WiMAX networks using the IEEE 802.21 Media Independent Handover (MIH) framework. It describes the need for integration of heterogeneous wireless networks to provide ubiquitous coverage and broadband connectivity. It explains homogeneous and heterogeneous handovers and the role of IEEE 802.21 in facilitating handovers across different network types. The MIH framework provides services and events to support handovers between WiFi and WiMAX networks in a seamless manner for mixed network clients.
Latest technologies used to transfer data using internetSaqlain Memon
this are the latest technologies used to transfer data in internet using this you can transfer data very easily be smart on the internet be protective in india for more information log in to saqlainmemon776@gmail.com find interesting things on this
Wireless networks allow devices to connect to a network without being physically connected with wires. They consist of wireless hosts that communicate over the air with network infrastructure like access points or base stations. There are challenges to wireless communication including signal attenuation, interference, and the hidden terminal problem. Wireless networks can operate in infrastructure mode with access points or in ad hoc mode without infrastructure between devices. Standards like 802.11 (Wi-Fi) and CDMA are used to allow multiple devices to communicate over the same wireless channel. Devices must associate with an access point to connect to the network and protocols like CSMA/CA are used to avoid collisions between transmissions.
This document analyzes the performance of Wi-Fi networks under three conditions: no fading, flat fading, and dispersive fading. It simulates these conditions using an IEEE 802.11a WLAN physical layer model in Matlab. The simulation measures packet error rate and bit rate as the signal-to-noise ratio and maximum Doppler shift are varied. With no fading, there is no packet error and bit rate increases with SNR. Under flat and dispersive fading, packet error and bit rates are affected differently based on the maximum Doppler shift. The best performance occurs under flat fading with a lower maximum Doppler shift of 100Hz.
Survey of Routing Scheme in MANET with Clustering TechniquesIJMER
This document provides an overview of routing schemes and clustering techniques in mobile ad hoc networks (MANETs). It discusses different routing protocols for MANETs including proactive, reactive, and hybrid protocols. Examples of proactive protocols mentioned are OLSR and DSDV, while reactive protocols include AODV and DSR. Hybrid protocols combine aspects of proactive and reactive routing, with examples being ZRP and CBRP. The document also surveys various clustering approaches for MANETs including location-based, neighbor-based, power-based, and mobility-based techniques. It analyzes the advantages and disadvantages of different routing protocols and clustering methods.
The document discusses du's broadband portfolio in the UAE, with a case study on implementing WiFi on the Dubai Metro. It outlines du's use of HSPA, WiMAX, and WiFi technologies for mobile and fixed broadband services. Specifically, du used WiMAX to provide the backhaul network for Metro WiFi access on trains and in stations. While HSPA has a smaller cell radius that shrinks with loading, WiMAX provides consistent coverage and can support more users at the cell edge achieving 512kbps throughput. Overall, WiMAX networks have higher capacity and lower latency than comparable HSPA networks.
This document discusses speed adaptive mobile IP over wireless LAN. It first analyzes the relationship between performance and moving speed for mobile IP over wireless LAN, showing that current mobile IP is not suitable for rapid movement. It then proposes a speed adaptive mobile IP protocol that extends registration messages with speed information to allow the network behavior to automatically adapt based on node speed, improving performance for rapid movement without high resource costs. The protocol is emulated and shown to greatly improve mobile IP performance for rapid movement over wireless LAN.
Introductory Approach on Ad-hoc Networks and its Paradigms IJORCS
This document provides an introductory overview of ad-hoc networks, including:
1) A definition of ad-hoc networks as decentralized wireless networks that self-configure without preexisting infrastructure;
2) A discussion of mobile ad-hoc networks (MANETs) and wireless sensor networks as examples of ad-hoc networks;
3) An overview of challenges in providing quality of service in ad-hoc networks given their dynamic topology.
This document provides an overview of key topics in chapter 6 on wireless and mobile networks. It begins with background on the growth of wireless networks and defines two main challenges - wireless communication over the wireless link, and handling mobility as users change their point of attachment. The chapter outline is then presented, covering wireless link characteristics, IEEE 802.11 wireless LANs, cellular networks, principles of addressing and routing for mobile users, and handling mobility. Elements of wireless networks like wireless hosts, base stations, and wireless links are defined. Characteristics of different wireless links are summarized and issues like interference, multipath propagation, and the hidden terminal problem are introduced.
This document provides an overview of wireless and mobile networks. It begins with background on the growth of wireless networks and devices. The key challenges of wireless communication over wireless links and handling mobility are introduced. The chapter outline covers wireless link characteristics, wireless local area networks (Wi-Fi), cellular networks, and principles of mobility. Elements of wireless networks like base stations, wireless hosts, and infrastructure and ad hoc modes are defined. Characteristics of different wireless links and issues like interference are also summarized.
The document provides an overview of wireless and mobile networks. It discusses key differences between wired and wireless links, including decreased signal strength over distance, interference from other devices, and multipath propagation. It also describes various wireless network characteristics such as signal-to-noise ratio tradeoffs, the hidden terminal problem, and how Code Division Multiple Access (CDMA) works to allow multiple users to transmit simultaneously using unique coding. The chapter outline and sections cover additional topics like IEEE 802.11 wireless networks, cellular network architectures and standards, principles of mobility, and handling mobility in different network types.
The document provides an overview of wireless and mobile networks. It discusses how wireless networks allow anytime untethered internet access for devices like laptops and phones. It also distinguishes between the challenges of wireless communication over a wireless link and handling mobility as users change their point of attachment. The chapter outline covers wireless link characteristics, wireless standards like 802.11 and CDMA, cellular internet access architectures and standards, principles of addressing and routing to mobile users, and protocols for mobility like Mobile IP.
Here are the key points about how mobility support for both the correspondent and mobile host would affect end-to-end delays:
- Datagrams would need to be tunneled through multiple home agents to reach the destination, adding additional encapsulation and forwarding hops.
- The path taken by a datagram would become more indirect as it travels through multiple home agents rather than direct host-to-host routing. This increases propagation and transmission delays.
- Additional processing is required at each home agent to encapsulate/decapsulate and forward the datagram, increasing processing delays.
- If either the mobile host or correspondent changes locations, their registrations with home agents and mobility bindings need to be updated, introducing additional
The document discusses the characteristics and security issues of wireless LANs (WLANs). It describes the advantages and disadvantages of WLANs, as well as their design goals and transmission technologies. It then discusses some specific wireless security issues for WLANs, including interception of radio signals, reliance on shared public infrastructure, and risks from rogue access points and war driving. Finally, it provides an overview of the IEEE 802.11 standard for WLANs, including its network architectures, transmission methods like CSMA/CA, frame types, and security features.
The document discusses the key elements and characteristics of wireless networks. It describes the different components of a wireless network including wireless hosts, base stations, wireless links, and the infrastructure and ad hoc modes. It then covers characteristics of wireless links such as decreased signal strength, interference, and multipath propagation that make wireless communication more difficult than wired networks. It also discusses wireless network issues like the hidden terminal problem and signal attenuation.
Wireless Technologies
Presented by
Sean Shields
And
Gabriel Taveras
Definition
Term “Wireless” refers to all the communications sent and received without wires.
So Wireless Technology
Means a technology that use radio waves to transmit or receive data.
Wi-Fi
Bluetooth
Cellular
Wimax
TYPES OF
TECHNOLOGIES
INTRODUCTION:
Wireless Fidelity termed as Wi-Fi uses the IEEE 802.11 specification to create a wireless local-area network.
A Wi-Fi network basically consists of a wired connection to the Internet that leads to a wireless router for transmutation and receiving data from individual devices, connecting them not only to the outside world but also to each other.
HOW WIFI WORKS?
1. All devices use a wireless adapter to convert request into a radio signal and broadcasts it into the air.
2. The Wi-Fi device, or wireless router, picks up the signal and translates it back into its original form.
3. The router passes the request to the Internet using a hardwired connection.
4. The Internet returns the requested information to the router across the same connection.
5. The router converts the information into a radio signal and broadcasts it into the air.
6. The computer or cell phone's wireless adapter picks up the information and displays it on your screen
WIFI TOPOLOGIES
Wifi have following topologies
AP-based topology (Infrastructure Mode)
Peer-to-peer topology (Ad-hoc Mode)
Point-to-multipoint bridge topology
Wi Fi Network
Wireless Standards
802.11
In 1997, the Institute of Electrical and Electronics Engineers (IEEE) created the first WLAN standard. They called it 802.11 after the name of the group formed to oversee its development. Unfortunately, 802.11 only supported a maximum network bandwidth of 2 Mbps - too slow for most applications. For this reason, ordinary 802.11 wireless products are no longer manufactured.
Wireless Standards
802.11b
IEEE expanded on the original 802.11 standard in July 1999, creating the 802.11b specification. 802.11b supports bandwidth up to 11 Mbps, comparable to traditional Ethernet.
Wireless Standards
802.11a
Supports bandwidth up to 54 Mbps and signals in a regulated frequency spectrum around 5 GHz. This higher frequency compared to 802.11b shortens the range of 802.11a networks. The higher frequency also means 802.11a signals have more difficulty penetrating walls and other obstructions.
Wireless Standards
802.11g
Attempts to combine the best of both 802.11a and 802.11b. 802.11g supports bandwidth up to 54 Mbps, and it uses the 2.4 Ghz frequency for greater range. 802.11g is backwards compatible with 802.11b, meaning that 802.11g access points will work with 802.11b wireless network adapters and vice versa.
Wireless Standards
802.11n
The newest IEEE standard in the Wi-Fi category is 802.11n.
802.11n connections support data rates of over 100 Mbps. 802.11n also offers somewhat better range over earlier Wi-Fi standards due to its increased signal.
This document provides an overview of Chapter 7 from the textbook "Computer Networking: A Top-Down Approach 8th edition" by Jim Kurose and Keith Ross. It discusses the use of the PowerPoint slides from the chapter and provides copyright information. The chapter outline is then presented, covering topics on wireless links and networks, WiFi (802.11), cellular networks, mobility management, and the impact of mobility on higher layer protocols.
This document provides an overview of Chapter 7 from the textbook "Computer Networking: A Top-Down Approach 8th edition" by Jim Kurose and Keith Ross. It includes notes on using the PowerPoint slides freely but asking users to cite the source and copyright. The chapter outline covers wireless links and networks, WiFi (802.11), cellular networks, and mobility management. It provides context on the growth of wireless and mobile networks and examples of wireless link characteristics, protocols, and WiFi frame addressing.
1) The document discusses route optimization techniques for solving the triangle routing problem in Mobile IPv4, specifically evaluating the performance of the Internet Service Provider Mobile Border Gateway (ISP MBG) scheme.
2) It provides background on Mobile IP, the triangle routing problem, and introduces the ISP MBG technique for optimizing routes.
3) The study evaluates the performance of ISP MBG by varying system parameters like number of nodes and zones, finding it provides shorter transmission times compared to conventional Mobile IP.
MANET stands for mobile ad hoc network. It is a type of wireless network that can change locations and configure itself without a centralized administration. Nodes in a MANET can connect to each other to form a temporary network without any existing network infrastructure. Routing in MANETs is challenging due to the dynamic network topology, asymmetric links, and interference. Common routing algorithms for MANETs include distance vector, link state, and various protocols designed specifically for MANETs to handle mobility.
MANET stands for mobile ad hoc network. It is a type of wireless network that can change locations and configure itself without a centralized administration. Nodes in a MANET can connect to each other to form a temporary network without any existing network infrastructure. Routing in MANETs is challenging due to the dynamic network topology, asymmetric links, and interference. Common routing algorithms for MANETs include distance vector, link state, and various protocols designed specifically for MANETs to handle mobility.
Wireless networks allow devices to connect to a network without being physically connected by cables. They work by transmitting radio signals that carry data between wireless devices and access points or base stations. There are different types of wireless networks including WLANs for local areas like campuses, WPANs for personal networks using technologies like Bluetooth, and WMANs for connecting multiple networks over a metropolitan area. Wireless networks offer mobility and flexibility compared to wired networks but have lower bandwidth and speeds. Common applications of wireless networks include mobile access to the internet, extending wired networks wirelessly, and connecting remote areas without wired infrastructure.
Module 4 emerging wireless technologies and standardsnikshaikh786
The document discusses emerging wireless technologies and standards covered in Module 4. It provides an overview of Wireless Local Loop (WLL) technology, including its need and architecture. WLL uses radio connectivity to provide telephone network access, replacing wired connections. It has advantages like lower costs and faster deployment compared to installing cables. The document also covers the IEEE 802.11 standard for Wireless Local Area Networks (WLANs), including the development of different standards, network architectures, and equipment.
The document summarizes key concepts about the data link layer. It discusses the goals and services of the data link layer, including error detection and correction, sharing broadcast channels through multiple access protocols, link layer addressing, and reliable data transfer and flow control. It also provides an overview of common link layer technologies and implementation through instantiation of various data link layer protocols.
This chapter discusses the network layer, including:
1) The key functions of the network layer including forwarding, routing, and connection setup.
2) Network layer service models such as best effort, connection-oriented, and guaranteed services.
3) The differences between virtual circuit and datagram networks, and how routers implement virtual circuits using forwarding tables and connection state information.
The document summarizes key concepts about the transport layer in computer networks. It discusses how the transport layer provides logical communication between application processes running on different hosts using protocols like TCP and UDP. TCP provides reliable, in-order delivery using congestion control and flow control, while UDP provides unreliable delivery without these features. The outline and chapters cover transport layer services, multiplexing/demultiplexing, connection-oriented transport with TCP, and congestion control principles.
The document summarizes key topics in network application layer protocols. It discusses principles of network applications and popular protocols like HTTP, FTP, SMTP, and DNS. It covers client-server and peer-to-peer architectures, socket programming, and how processes are addressed. The document also examines common network applications and the transport service requirements around data loss, bandwidth needs, and time sensitivity.
This document provides an overview of CMPSCI 453, an introductory computer networking course. The course will be taught by Professor Jim Kurose and will cover networking principles and the Internet architecture using a top-down approach. Students will learn about topics like physical media, protocol layers, routing, and link-level protocols. The workload includes homework assignments, programming projects, lab assignments, and exams. All course materials will be available on the class website at gaia.cs.umass.edu/cs453.
The document summarizes key concepts in network security including cryptography, authentication, integrity, and access control. It discusses principles like confidentiality, authentication, and integrity. It introduces common examples of Alice, Bob, and Trudy to illustrate security concepts and the need to protect against eavesdropping, impersonation, message alteration, and denial of service attacks. Symmetric and public key cryptography algorithms are overviewed including DES, AES, and RSA.
This document provides an overview and introduction to the key concepts of computer networks and the Internet. It discusses what the Internet is, including its nuts and bolts view consisting of interconnected hosts, communication links, and routers. It also covers the network edge consisting of end systems and various access networks, the network core consisting of interconnected routers, and different types of physical media used for communication links. Key concepts explained include circuit switching versus packet switching, protocols, and the layered architecture of the Internet.
1. Chapter 6: Wireless and Mobile Networks
Background:
# wireless (mobile) phone subscribers now
exceeds # wired phone subscribers!
computer nets: laptops, palmtops, PDAs,
Internet-enabled phone promise anytime
untethered Internet access
two important (but different) challenges
communication over wireless link
handling mobile user who changes point of
attachment to network
6: Wireless and Mobile Networks 6-1
Chapter 6 outline
6.1 Introduction Mobility
6.5 Principles:
Wireless addressing and routing
6.2 Wireless links, to mobile users
characteristics 6.6 Mobile IP
CDMA 6.7 Handling mobility in
6.3 IEEE 802.11 cellular networks
wireless LANs (“wi-fi”) 6.8 Mobility and higher-
6.4 Cellular Internet layer protocols
Access
architecture 6.9 Summary
standards (e.g., GSM)
6: Wireless and Mobile Networks 6-2
1
2. Elements of a wireless network
wireless hosts
laptop, PDA, IP phone
run applications
may be stationary
(non-mobile) or mobile
network wireless does not
infrastructure always mean mobility
6: Wireless and Mobile Networks 6-3
Elements of a wireless network
base station
typically connected to
wired network
relay - responsible
for sending packets
between wired
network network and wireless
infrastructure host(s) in its “area”
e.g., cell towers
802.11 access
points
6: Wireless and Mobile Networks 6-4
2
3. Elements of a wireless network
wireless link
typically used to
connect mobile(s) to
base station
also used as backbone
link
network multiple access
infrastructure protocol coordinates
link access
various data rates,
transmission distance
6: Wireless and Mobile Networks 6-5
Characteristics of selected wireless link
standards
54 Mbps 802.11{a,g}
5-11 Mbps 802.11b .11 p-to-p link
1 Mbps
802.15
3G
384 Kbps UMTS/WCDMA, CDMA2000
2G
56 Kbps IS-95 CDMA, GSM
Indoor Outdoor Mid range Long range
outdoor outdoor
10 – 30m 50 – 200m 200m – 4Km 5Km – 20Km
6: Wireless and Mobile Networks 6-6
3
4. Elements of a wireless network
infrastructure mode
base station connects
mobiles into wired
network
handoff: mobile
changes base station
network providing connection
infrastructure into wired network
6: Wireless and Mobile Networks 6-7
Elements of a wireless network
Ad hoc mode
no base stations
nodes can only
transmit to other
nodes within link
coverage
nodes organize
themselves into a
network: route among
themselves
6: Wireless and Mobile Networks 6-8
4
5. Wireless Link Characteristics
Differences from wired link ….
decreased signal strength: radio signal
attenuates as it propagates through matter
(path loss)
interference from other sources: standardized
wireless network frequencies (e.g., 2.4 GHz)
shared by other devices (e.g., phone); devices
(motors) interfere as well
multipath propagation: radio signal reflects off
objects ground, arriving ad destination at
slightly different times
…. make communication across (even a point to point)
wireless link much more “difficult”
6: Wireless and Mobile Networks 6-9
Wireless network characteristics
Multiple wireless senders and receivers create
additional problems (beyond multiple access):
A B C
C
A’s signal C’s signal
B strength strength
A
space
Hidden terminal problem
B, A hear each other Signal fading:
B, C hear each other B, A hear each other
A, C can not hear each other B, C hear each other
means A, C unaware of their A, C can not hear each other
interference at B interferring at B
6: Wireless and Mobile Networks 6-10
5
6. Code Division Multiple Access (CDMA)
used in several wireless broadcast channels
(cellular, satellite, etc) standards
unique “code” assigned to each user; i.e., code set
partitioning
all users share same frequency, but each user has
own “chipping” sequence (i.e., code) to encode data
encoded signal = (original data) X (chipping
sequence)
decoding: inner-product of encoded signal and
chipping sequence
allows multiple users to “coexist” and transmit
simultaneously with minimal interference (if codes
are “orthogonal”)
6: Wireless and Mobile Networks 6-11
CDMA Encode/Decode
channel output Zi,m
Zi,m= di.cm
data d0 = 1
1 1 1 1 1 1 1 1
d1 = -1
bits
sender
-1 -1 -1 -1 -1 -1 -1 -1
1 1 1 1 1 1 1 1 slot 1 slot 0
code channel channel
-1 -1 -1 -1 -1 -1 -1 -1
output output
slot 1 slot 0
M
Di = Σ Zi,m.cm
m=1
M
received 1 1 1 1 1 1 1 1
d0 = 1
-1 -1 -1 -1 -1 -1 -1 -1
input d1 = -1
1 1 1 1 1 1 1 1 slot 1 slot 0
code channel channel
-1 -1 -1 -1 -1 -1 -1 -1
receiver slot 1 slot 0
output output
6: Wireless and Mobile Networks 6-12
6
7. CDMA: two-sender interference
6: Wireless and Mobile Networks 6-13
Chapter 6 outline
6.1 Introduction Mobility
6.5 Principles:
Wireless addressing and routing
6.2 Wireless links, to mobile users
characteristics 6.6 Mobile IP
CDMA 6.7 Handling mobility in
6.3 IEEE 802.11 cellular networks
wireless LANs (“wi-fi”) 6.8 Mobility and higher-
6.4 Cellular Internet layer protocols
Access
architecture 6.9 Summary
standards (e.g., GSM)
6: Wireless and Mobile Networks 6-14
7
8. IEEE 802.11 Wireless LAN
802.11b 802.11a
2.4-5 GHz unlicensed 5-6 GHz range
radio spectrum up to 54 Mbps
up to 11 Mbps 802.11g
direct sequence spread
2.4-5 GHz range
spectrum (DSSS) in
physical layer up to 54 Mbps
• all hosts use same All use CSMA/CA for
chipping code multiple access
widely deployed, using All have base-station
base stations
and ad-hoc network
versions
6: Wireless and Mobile Networks 6-15
802.11 LAN architecture
wireless host communicates
Internet with base station
base station = access
point (AP)
Basic Service Set (BSS)
(aka “cell”) in infrastructure
hub, switch
or router mode contains:
AP
wireless hosts
BSS 1 access point (AP): base
station
AP
ad hoc mode: hosts only
BSS 2
6: Wireless and Mobile Networks 6-16
8
9. 802.11: Channels, association
802.11b: 2.4GHz-2.485GHz spectrum divided into
11 channels at different frequencies
AP admin chooses frequency for AP
interference possible: channel can be same as
that chosen by neighboring AP!
host: must associate with an AP
scans channels, listening for beacon frames
containing AP’s name (SSID) and MAC address
selects AP to associate with
may perform authentication [Chapter 8]
will typically run DHCP to get IP address in AP’s
subnet
6: Wireless and Mobile Networks 6-17
IEEE 802.11: multiple access
avoid collisions: 2+ nodes transmitting at same time
802.11: CSMA - sense before transmitting
don’t collide with ongoing transmission by other node
802.11: no collision detection!
difficult to receive (sense collisions) when transmitting due
to weak received signals (fading)
can’t sense all collisions in any case: hidden terminal, fading
goal: avoid collisions: CSMA/C(ollision)A(voidance)
A B C
C
A’s signal C’s signal
B strength strength
A
space
6: Wireless and Mobile Networks 6-18
9
10. IEEE 802.11 MAC Protocol: CSMA/CA
802.11 sender
1 if sense channel idle for DIFS then sender receiver
transmit entire frame (no CD)
2 if sense channel busy then DIFS
start random backoff time
timer counts down while channel idle data
transmit when timer expires
if no ACK, increase random backoff
SIFS
interval, repeat 2
802.11 receiver ACK
- if frame received OK
return ACK after SIFS (ACK needed due
to hidden terminal problem)
6: Wireless and Mobile Networks 6-19
Avoiding collisions (more)
idea: allow sender to “reserve” channel rather than random
access of data frames: avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets
to BS using CSMA
RTSs may still collide with each other (but they’re short)
BS broadcasts clear-to-send CTS in response to RTS
RTS heard by all nodes
sender transmits data frame
other stations defer transmissions
Avoid data frame collisions completely
using small reservation packets!
6: Wireless and Mobile Networks 6-20
10
11. Collision Avoidance: RTS-CTS exchange
A B
AP
RTS(A) RTS(B)
reservation collision
RTS(A)
CTS(A) CTS(A)
DATA (A)
defer
time
ACK(A) ACK(A)
6: Wireless and Mobile Networks 6-21
802.11 frame: addressing
2 2 6 6 6 2 6 0 - 2312 4
frame address address address seq address
duration payload CRC
control 1 2 3 control 4
Address 4: used only
in ad hoc mode
Address 1: MAC address
of wireless host or AP Address 3: MAC address
to receive this frame of router interface to
which AP is attached
Address 2: MAC address
of wireless host or AP
transmitting this frame
6: Wireless and Mobile Networks 6-22
11
12. 802.11 frame: addressing
Internet
H1 R1 router
AP
R1 MAC addr AP MAC addr
dest. address source address
802.3 frame
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
802.11 frame
6: Wireless and Mobile Networks 6-23
802.11 frame: more
frame seq #
duration of reserved
(for reliable ARQ)
transmission time (RTS/CTS)
2 2 6 6 6 2 6 0 - 2312 4
frame address address address seq address
duration payload CRC
control 1 2 3 control 4
2 2 4 1 1 1 1 1 1 1 1
Protocol To From More Power More
Type Subtype Retry WEP Rsvd
version AP AP frag mgt data
frame type
(RTS, CTS, ACK, data)
6: Wireless and Mobile Networks 6-24
12
13. 802.11: mobility within same subnet
H1 remains in same IP router
subnet: IP address
can remain same hub or
switch: which AP is switch
associated with H1? BBS 1
self-learning (Ch. 5):
switch will see frame AP 1
from H1 and AP 2
“remember” which
switch port can be H1 BBS 2
used to reach H1
6: Wireless and Mobile Networks 6-25
802.15: personal area network
less than 10 m diameter
replacement for cables
(mouse, keyboard, S
P
headphones) P radius of
ad hoc: no infrastructure
M
coverage
master/slaves: S S P
P
slaves request permission to
send (to master)
master grants requests
802.15: evolved from M Master device
Bluetooth specification S Slave device
2.4-2.5 GHz radio band P Parked device (inactive)
up to 721 kbps
6: Wireless and Mobile Networks 6-26
13
14. Chapter 6 outline
6.1 Introduction Mobility
6.5 Principles:
Wireless addressing and routing
6.2 Wireless links, to mobile users
characteristics 6.6 Mobile IP
CDMA 6.7 Handling mobility in
6.3 IEEE 802.11 cellular networks
wireless LANs (“wi-fi”) 6.8 Mobility and higher-
6.4 Cellular Internet layer protocols
Access
architecture 6.9 Summary
standards (e.g., GSM)
6: Wireless and Mobile Networks 6-27
Components of cellular network architecture
MSC
connects cells to wide area net
manages call setup (more later!)
handles mobility (more later!)
cell
covers geographical
region
base station (BS) Mobile
analogous to 802.11 AP Switching
mobile users attach
Center
Public telephone
to network through BS network, and
air-interface: Internet
physical and link layer Mobile
protocol between Switching
mobile and BS Center
wired network
6: Wireless and Mobile Networks 6-28
14
15. Cellular networks: the first hop
Two techniques for sharing
mobile-to-BS radio
spectrum
combined FDMA/TDMA:
divide spectrum in time slots
frequency channels, divide
each channel into time
slots frequency
CDMA: code division bands
multiple access
6: Wireless and Mobile Networks 6-29
Cellular standards: brief survey
2G systems: voice channels
IS-136 TDMA: combined FDMA/TDMA (north
america)
GSM (global system for mobile communications):
combined FDMA/TDMA
most widely deployed
IS-95 CDMA: code division multiple access
TDMA/FDMA
CDMA-2000
GPRS EDGE UMT Don’t drown in a bowl
IS-136 S
GSM IS-95 of alphabet soup: use this
oor reference only
6: Wireless and Mobile Networks 6-30
15
16. Cellular standards: brief survey
2.5 G systems: voice and data channels
for those who can’t wait for 3G service: 2G extensions
general packet radio service (GPRS)
evolved from GSM
data sent on multiple channels (if available)
enhanced data rates for global evolution (EDGE)
also evolved from GSM, using enhanced modulation
Date rates up to 384K
CDMA-2000 (phase 1)
data rates up to 144K
evolved from IS-95
6: Wireless and Mobile Networks 6-31
Cellular standards: brief survey
3G systems: voice/data
Universal Mobile Telecommunications Service (UMTS)
GSM next step, but using CDMA
CDMA-2000
….. more (and more interesting) cellular topics due to
mobility (stay tuned for details)
6: Wireless and Mobile Networks 6-32
16
17. Chapter 6 outline
6.1 Introduction Mobility
6.5 Principles:
Wireless addressing and routing
6.2 Wireless links, to mobile users
characteristics 6.6 Mobile IP
CDMA 6.7 Handling mobility in
6.3 IEEE 802.11 cellular networks
wireless LANs (“wi-fi”) 6.8 Mobility and higher-
6.4 Cellular Internet layer protocols
Access
architecture 6.9 Summary
standards (e.g., GSM)
6: Wireless and Mobile Networks 6-33
What is mobility?
spectrum of mobility, from the network perspective:
no mobility high mobility
mobile wireless user, mobile user, mobile user, passing
using same access connecting/ through multiple
point disconnecting access point while
from network maintaining ongoing
using DHCP. connections (like cell
phone)
6: Wireless and Mobile Networks 6-34
17
18. Mobility: Vocabulary
home network: permanent home agent: entity that will
“home” of mobile perform mobility functions on
(e.g., 128.119.40/24)
behalf of mobile, when mobile
is remote
wide area
network
Permanent address:
address in home
network, can always be
used to reach mobile
e.g., 128.119.40.186 correspondent
6: Wireless and Mobile Networks 6-35
Mobility: more vocabulary
visited network: network
Permanent address: remains in which mobile currently
constant (e.g., 128.119.40.186) resides (e.g., 79.129.13/24)
Care-of-address: address
in visited network.
(e.g., 79,129.13.2)
wide area
network
home agent: entity in
visited network that
performs mobility
correspondent: wants functions on behalf
to communicate with of mobile.
mobile 6: Wireless and Mobile Networks 6-36
18
19. How do you contact a mobile friend:
Consider friend frequently changing I wonder where
addresses, how do you find her? Alice moved to?
search all phone
books?
call her parents?
expect her to let you
know where he/she is?
6: Wireless and Mobile Networks 6-37
Mobility: approaches
Let routing handle it: routers advertise permanent
address of mobile-nodes-in-residence via usual
routing table exchange.
routing tables indicate where each mobile located
no changes to end-systems
Let end-systems handle it:
indirect routing: communication from
correspondent to mobile goes through home
agent, then forwarded to remote
direct routing: correspondent gets foreign
address of mobile, sends directly to mobile
6: Wireless and Mobile Networks 6-38
19
20. Mobility: approaches
Let routing handle it: routers advertise permanent
address of mobile-nodes-in-residence via usual
not
scalable
routing table exchange.
to millions of
routing tables indicate where each mobile located
mobiles
no changes to end-systems
let end-systems handle it:
indirect routing: communication from
correspondent to mobile goes through home
agent, then forwarded to remote
direct routing: correspondent gets foreign
address of mobile, sends directly to mobile
6: Wireless and Mobile Networks 6-39
Mobility: registration
visited network
home network
1
2
wide area
network
mobile contacts
foreign agent contacts home foreign agent on
agent home: “this mobile is entering visited
resident in my network” network
End result:
Foreign agent knows about mobile
Home agent knows location of mobile
6: Wireless and Mobile Networks 6-40
20
21. Mobility via Indirect Routing
foreign agent
receives packets,
home agent intercepts forwards to mobile
packets, forwards to visited
foreign agent network
home
network
3
wide area
network
2
1
correspondent 4
addresses packets
mobile replies
using home address
directly to
of mobile
correspondent
6: Wireless and Mobile Networks 6-41
Indirect Routing: comments
Mobile uses two addresses:
permanent address: used by correspondent (hence
mobile location is transparent to correspondent)
care-of-address: used by home agent to forward
datagrams to mobile
foreign agent functions may be done by mobile itself
triangle routing: correspondent-home-network-
mobile
inefficient when
correspondent, mobile
are in same network
6: Wireless and Mobile Networks 6-42
21
22. Indirect Routing: moving between networks
suppose mobile user moves to another
network
registers with new foreign agent
new foreign agent registers with home agent
home agent update care-of-address for mobile
packets continue to be forwarded to mobile (but
with new care-of-address)
mobility, changing foreign networks
transparent: on going connections can be
maintained!
6: Wireless and Mobile Networks 6-43
Mobility via Direct Routing
foreign agent
receives packets,
correspondent forwards forwards to mobile
to foreign agent visited
network
home
network 4
wide area
2 network
3
correspondent 1 4
requests, receives
mobile replies
foreign address of
directly to
mobile
correspondent
6: Wireless and Mobile Networks 6-44
22
23. Mobility via Direct Routing: comments
overcome triangle routing problem
non-transparent to correspondent:
correspondent must get care-of-address
from home agent
what if mobile changes visited network?
6: Wireless and Mobile Networks 6-45
Accommodating mobility with direct routing
anchor foreign agent: FA in first visited network
data always routed first to anchor FA
when mobile moves: new FA arranges to have data
forwarded from old FA (chaining)
foreign net visited
at session start
anchor
foreign
wide area agent
2
network
1 4
3
5
new
correspondent foreign
new foreign
agent network
correspondent agent
6: Wireless and Mobile Networks 6-46
23
24. Chapter 6 outline
6.1 Introduction Mobility
6.5 Principles:
Wireless addressing and routing
6.2 Wireless links, to mobile users
characteristics 6.6 Mobile IP
CDMA 6.7 Handling mobility in
6.3 IEEE 802.11 cellular networks
wireless LANs (“wi-fi”) 6.8 Mobility and higher-
6.4 Cellular Internet layer protocols
Access
architecture 6.9 Summary
standards (e.g., GSM)
6: Wireless and Mobile Networks 6-47
Mobile IP
RFC 3220
has many features we’ve seen:
home agents, foreign agents, foreign-agent
registration, care-of-addresses, encapsulation
(packet-within-a-packet)
three components to standard:
indirect routing of datagrams
agent discovery
registration with home agent
6: Wireless and Mobile Networks 6-48
24
25. Mobile IP: indirect routing
foreign-agent-to-mobile packet
packet sent by home agent to foreign dest: 128.119.40.186
agent: a packet within a packet
dest: 79.129.13.2 dest: 128.119.40.186
Permanent address:
128.119.40.186
Care-of address:
79.129.13.2
dest: 128.119.40.186
packet sent by
correspondent
6: Wireless and Mobile Networks 6-49
Mobile IP: agent discovery
agent advertisement: foreign/home agents advertise
service by broadcasting ICMP messages (typefield = 9)
0 8 16 24
type = 9 code = 0 checksum
H,F bits: home standard
and/or foreign agent router address ICMP fields
R bit: registration
required type = 16 length sequence #
RBHFMGV
registration lifetime reserved
bits mobility agent
advertisement
0 or more care-of- extension
addresses
6: Wireless and Mobile Networks 6-50
25
26. Mobile IP: registration example
visited network: 79.129.13/24
home agent foreign agent
HA: 128.119.40.7 COA: 79.129.13.2 ICMP agent adv.
Mobile agent
COA: 79.129.13.2 MA: 128.119.40.186
….
registration req.
registration req. COA: 79.129.13.2
COA: 79.129.13.2 HA: 128.119.40.7
HA: 128.119.40.7 MA: 128.119.40.186
MA: 128.119.40.186 Lifetime: 9999
Lifetime: 9999 identification:714
identification: 714 ….
encapsulation format
….
registration reply
time HA: 128.119.40.7 registration reply
MA: 128.119.40.186
Lifetime: 4999 HA: 128.119.40.7
Identification: 714 MA: 128.119.40.186
encapsulation format Lifetime: 4999
…. Identification: 714
….
6: Wireless and Mobile Networks 6-51
Components of cellular network architecture
recall: correspondent
wired public
telephone
network
MSC MSC
MSC
MSC
MSC
different cellular networks,
operated by different providers
6: Wireless and Mobile Networks 6-52
26
27. Handling mobility in cellular networks
home network: network of cellular provider you
subscribe to (e.g., Sprint PCS, Verizon)
home location register (HLR): database in home
network containing permanent cell phone #,
profile information (services, preferences,
billing), information about current location
(could be in another network)
visited network: network in which mobile currently
resides
visitor location register (VLR): database with
entry for each user currently in network
could be home network
6: Wireless and Mobile Networks 6-53
GSM: indirect routing to mobile
home
HLR network correspondent
2
home
Mobile
home MSC consults HLR, Switching
gets roaming number of Center
mobile in visited network
1 call routed
to home network
3 Public
VLR switched
Mobile
telephone
Switching
network
Center
4
home MSC sets up 2nd leg of call
to MSC in visited network
mobile
user MSC in visited network completes
visited call through base station to mobile
network
6: Wireless and Mobile Networks 6-54
27
28. GSM: handoff with common MSC
Handoff goal: route call via
new base station (without
interruption)
VLR Mobile reasons for handoff:
Switching stronger signal to/from new
Center
BSS (continuing connectivity,
less battery drain)
load balance: free up channel
old new
routing routing
old BSS
in current BSS
new BSS
GSM doesn’t mandate why to
perform handoff (policy), only
how (mechanism)
handoff initiated by old BSS
6: Wireless and Mobile Networks 6-55
GSM: handoff with common MSC
1. old BSS informs MSC of impending
handoff, provides list of 1+ new BSSs
2. MSC sets up path (allocates resources)
to new BSS
VLR Mobile 3. new BSS allocates radio channel for
Switching
Center 2 use by mobile
4 4. new BSS signals MSC, old BSS: ready
1
7
8 5. old BSS tells mobile: perform handoff to
3
old BSS 5 6
new BSS
new BSS
6. mobile, new BSS signal to activate new
channel
7. mobile signals via new BSS to MSC:
handoff complete. MSC reroutes call
8 MSC-old-BSS resources released
6: Wireless and Mobile Networks 6-56
28
29. GSM: handoff between MSCs
anchor MSC: first MSC
visited during cal
home network
correspondent call remains routed
Home
MSC through anchor MSC
new MSCs add on to end
anchor MSC
PSTN of MSC chain as mobile
moves to new MSC
MSC
MSC
MSC
IS-41 allows optional
path minimization step
to shorten multi-MSC
chain
(a) before handoff
6: Wireless and Mobile Networks 6-57
GSM: handoff between MSCs
anchor MSC: first MSC
visited during cal
home network
correspondent call remains routed
Home
MSC through anchor MSC
new MSCs add on to end
anchor MSC
PSTN of MSC chain as mobile
moves to new MSC
MSC
MSC
MSC
IS-41 allows optional
path minimization step
to shorten multi-MSC
chain
(b) after handoff
6: Wireless and Mobile Networks 6-58
29
30. Mobility: GSM versus Mobile IP
GSM element Comment on GSM element Mobile IP element
Home system Network to which the mobile user’s permanent Home network
phone number belongs
Gateway Mobile Home MSC: point of contact to obtain routable Home agent
Switching Center, or address of mobile user. HLR: database in
“home MSC”. Home home system containing permanent phone
Location Register number, profile information, current location of
(HLR) mobile user, subscription information
Visited System Network other than home system where Visited network
mobile user is currently residing
Visited Mobile Visited MSC: responsible for setting up calls Foreign agent
services Switching to/from mobile nodes in cells associated with
Center. MSC. VLR: temporary database entry in
Visitor Location visited system, containing subscription
Record (VLR) information for each visiting mobile user
Mobile Station Routable address for telephone call segment Care-of-
Roaming Number between home MSC and visited MSC, visible address
(MSRN), or “roaming to neither the mobile nor the correspondent.
number”
6: Wireless and Mobile Networks 6-59
Wireless, mobility: impact on higher layer protocols
logically, impact should be minimal …
best effort service model remains unchanged
TCP and UDP can (and do) run over wireless, mobile
… but performance-wise:
packet loss/delay due to bit-errors (discarded
packets, delays for link-layer retransmissions), and
handoff
TCP interprets loss as congestion, will decrease
congestion window un-necessarily
delay impairments for real-time traffic
limited bandwidth of wireless links
6: Wireless and Mobile Networks 6-60
30
31. Chapter 6 Summary
Wireless Mobility
wireless links: principles: addressing,
capacity, distance routing to mobile users
channel impairments home, visited networks
CDMA direct, indirect routing
IEEE 802.11 (“wi-fi”) care-of-addresses
CSMA/CA reflects case studies
wireless channel mobile IP
characteristics mobility in GSM
cellular access impact on higher-layer
architecture protocols
standards (e.g., GSM,
CDMA-2000, UMTS)
6: Wireless and Mobile Networks 6-61
31