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A
TRAINING REPORT
Submitted
In partial fulfillment
For the award of the Degree of
Bachelor of Technology
In Department of ...
B.S. Anangpuria Institute of Technology
And Management

‘

2
ACKNOWLEDGEMENT

It is my privilege to express my deep sense of gratitude towards all those who
helped me to undertake tra...
 Table of Contents :1. Company profile

……..

5.

2. Introduction to cognitive radio
And dynamic spectrum access

………

10...
COMPANY
PROFILE
5
The MINISTRY OF COMMUNICATION AND INFORMATION
TECHNOLOGY is an Indian government ministry.

3.1 VISION OF THE DEPARTMENT
e...
3.3 OBJECTIVE OF THE DEPARTMENT OF ELECTRONICS
AND INFORMATION TECHNOLOGY

•

e-Government: Providing e-infrastructure for...
a staggering US$ 46.3 billion in 2008-09, the IT sector currently
employing 2.2 million professionals directly and another...
ORGANISATIONAL CHART OF DEPARTMENT OF
ELECTRONICS AND INFORMATION
TECHNOLOGY(DEITY)

INTRODUCTION :
A cognitive radio is a...
channels
in wireless
spectrum,
then
accordingly
changes
its transmission or reception parameters
to
allow
more
concurrent ...
THE RADIO spectrum, which is needed for wireless communication
systems, is a naturally limited resource.
To support variou...
be equipped. For example, a CR may sense the ON/OFF status of
the PUs or can predict the interference power level that
is ...
of digital signal processing (DSP) techniques arose due to the efforts of
such leaders as Alan Oppenheim , Lawrence Rabine...
(SDR). An SDR, for example, might use a fast tuning synthesizer to hop a
3 MHz instantaneous baseband bandwidth over a 200...
Fig 1. Dimensions of Software Radio Implementations
.

In the commercial sector, for example, a dual antenna-RF stage coul...
There are, however, many other comprehensive, precise models of the
internal architecture of a radio. The architecture mod...
structure of the software that establishes conditions under which
composition of software modules is well behaved [139]. S...
communications. It has become very difficult to allocate new frequencies
for new wireless services. To solve the problem, ...


The procedure of a cognitive terminal to establish a communication
channel consists of following three steps.

1. The f...
2. Spectrum sharing type :
On the other hand, the method to use vacant frequency bands is called
spectrum sharing type (or...
Configuration of cognitive radio network
When a cognitive radio technology is applied to heterogeneous (consists of
differ...
Key technologies
 Hardware platform :
Figure- shows a typical configuration of a cognitive terminal consisting of
hardwar...
• Equip an open access point interface (API)
• Easily changeable parameters for spectrum sensing
• Equip arranged profilin...
24
Cognitive Networks and the Internet
The research questions and answers essential to building cognitive radio
networks are,...
recently sensed to other CRNs in the network. The entry for each emitter might
include a frequency range, time, and spatia...
Dynamically programmable capability according to radio environment to transmit and
receive on a variety of frequencies i.e...
.

resource for CR users.

FUTURE APPLICATIONS :
Cognitive radio technology can be used in a variety of applications in th...
•

Vehicular Communication: In the vehicular domain, the CR could be used
to enhance and improve intelligent interactions ...
system adaptation algorithms and emergent system behaviour. A major
hurdle to continued progress in the field is the inabi...
guaranteed with minimum latency. In addition, emergency communication requires a
significant amount of radio spectrum for ...
paid in order to guarantee an effcient usage of the wireless medium while
simultaneously providing fairness between compet...
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  1. 1. A TRAINING REPORT Submitted In partial fulfillment For the award of the Degree of Bachelor of Technology In Department of Electronics and Communication Engineering ACADEMIC SESSION 2013 - 2014 Submitted By: Student Name – JATIN KUMAR Student Roll no. – 10/ EL/ 038 SEM: - 6th Submitted To: Mr. B.M. Baveja. 1
  2. 2. B.S. Anangpuria Institute of Technology And Management ‘ 2
  3. 3. ACKNOWLEDGEMENT It is my privilege to express my deep sense of gratitude towards all those who helped me to undertake training in ELECTRONICS NIKETAN, Ministry of Communication and Information technology, GOVT. OF INDIA. I would like to express my sincere thanks to Mr. B.M. Baveja. (Training coordinator),Ministry of Communication and Information Technology for his guidance, valuable suggestions & encouragement during the project. 3
  4. 4.  Table of Contents :1. Company profile …….. 5. 2. Introduction to cognitive radio And dynamic spectrum access ……… 10. 3. History and Background Leading to Cognitive Radio …….. 12. 4. Basic concept of cognitive radio …….. 17. 5. Configuration of cognitive radio network …….. 21. 6. Key technologies ……… 22. 7. Cognitive Networks and the Internet ………… 25. 8. Features Of Cognitive Radio ………… 26. 9. Spectrum Hole Concept ……….. 27. ……… 28. 10. Future Applications 4
  5. 5. COMPANY PROFILE 5
  6. 6. The MINISTRY OF COMMUNICATION AND INFORMATION TECHNOLOGY is an Indian government ministry. 3.1 VISION OF THE DEPARTMENT e-Development of India as the engine for transition into a developed nation and an empowered society. 3.2 MISSION OF THE DEPARTMENT e-Development of India through multi pronged strategy of eInfrastructure creation to facilitate and promote e-governance, promotion of Electronics & Information Technology- Information Technology Enabled Services (IT-ITeS) Industry, providing support for creation of Innovation / Research & Development (R&D), building Knowledge network and securing India's cyber space. 6
  7. 7. 3.3 OBJECTIVE OF THE DEPARTMENT OF ELECTRONICS AND INFORMATION TECHNOLOGY • e-Government: Providing e-infrastructure for delivery of e-services. • e-Industry: Promotion of electronics hardware manufacturing and ITITeS industry. • e-Innovation / R & D: Providing Support for creation of Innovation Infrastructure in emerging areas of technology. • e-Education: Providing support for development of e-Skills and Knowledge network. • e-Security: Securing India's cyber space. 3.4 CC&BT (COMMUNICATION CONVERGENCE AND BROADBAND TECHNOLOGY DEPARTMENT) Information Technology has made possible information access at gigabit speeds. It has created a level playing field among nations and has made positive impact on the lives of millions who are poor, marginalised and living in rural and far flung topographies. Internet has made revolutionary changes with possibilities of e-filing Income Tax returns or applying for passports online or railway e-ticketing. Today a country’s IT potential is paramount for its march towards global competitiveness, healthy GDP, improving defence capabilities and meeting up the energy and environmental challenges. The Indian Information Technology- Information TechnologyEnabled Services (IT-ITES) industry has continued to perform its role as the most consistent growth driver for the economy. Service, software exports and BPO remain the mainstay of the sector. Over the last five years, the IT & ITES industry has grown at a remarkable pace. Consider some of the significant indicators for these remarkable achievements. The IT/ITES exports have grown to 7
  8. 8. a staggering US$ 46.3 billion in 2008-09, the IT sector currently employing 2.2 million professionals directly and another 8 million people indirectly accounts for over 5% of GDP, a majority of the Fortune 500 and Global 2000 corporations are sourcing IT/ITES from India and it is the premier destination for the global sourcing of IT/ITES accounting for 55% of the global market in offshore IT services and garnering 35% of the ITES/BPO market. 3.5 FUNCTIONS OF DEPARTMENT OF ELECTRONICS AND INFORMATION TECHNOLOGY The Allocation of Business Rules Pertaining to Department of Electronics and Information Technology. • • • • • • • • • • • • • Policy matters relating to information technology; Electronics;and Internet(all matters other than licensing of Internet Service Provider). Promotion of internet,IT and IT enabled services. Assistance to other departments in the promotion of E–Governance,E– Commerce,E–Medicine,E–Infrastructure,etc. Promotion of Information Technology education and Information Technology– based education. Matters relating to Cyber Laws,administration of the Information Technology Act.2000 (21 of 2000) and other IT related laws. Matters relating to promotion and manufacturing of Semiconductor Devices in the country excluding all matters relating to Semiconductor Complex Limited (SCL),Mohali ;The Semiconductor Integrated Circuits layout Design Act,2000 (37 of 2000). Interaction in IT related matters with international agencies and bodies e.g. Internet for Business Limited(IFB),Institute for Education in Information Society (IBI) and International Code Council – on line (ICC). Initiative on bridging the Digital Divide :Matters relating to Media Lab Asia. Promotion of Standardization,Testing and Quality in IT and standardization of procedure for IT application and Tasks. Electronics Export and Computer Software Promotion Council (ESC). National Informatics Centre (NIC). Initiatives for development of Hardware/Software industry including knowledge–based enterprise, measures for promoting IT exports and competitiveness of the industry. All matters relating to personnel under the control of the Department. 8
  9. 9. ORGANISATIONAL CHART OF DEPARTMENT OF ELECTRONICS AND INFORMATION TECHNOLOGY(DEITY) INTRODUCTION : A cognitive radio is a transceiver designed to use the best wireless channels in its vicinity. Such a radio automatically detects available 9
  10. 10. channels in wireless spectrum, then accordingly changes its transmission or reception parameters to allow more concurrent wireless communications in a given spectrum band at one location. Depending on transmission and reception parameters. There are two main types of cognitive radio : 1.Full Cognitive Radio (Mitola radio), in which every possible parameter observable by a wireless node (or network) is considered 2.Spectrum-Sensing Cognitive Radio, in which only the radio-frequency spectrum is considered.  Cognitive radio : A term first coined by Mitola is a low cost, highly flexible alternative to the classic single frequency band, single protocol wireless device. By sensing and adapting to its environment, a cognitive radio is able to cleverly avoid interference and fill voids in the wireless spectrum, dramatically increasing spectral efficiency. This dissertation defines and develops cognitive radio, the integration of model-based reasoning with software radio technologies. It analyzes the architecture and performance of a rapid-prototype cognitive radio, CR1 in a simulated environment. This architecture is based on the set-theoretic ontology of radio knowledge defined in the Radio Knowledge Representation Language (RKRL). CR1 incorporates machine-learning techniques to embrace the open domain framework of RKRL. These machine learning techniques make the software-radio trainable in a broad sense, instead of just programmable. Although somewhat primitive, CR1’s level of computational intelligence provides useful insights into the research issues surrounding cognitive radio. CR1 integrates aspects of digital signal processing, speech processing, theory of computing, rulebased expert systems, natural language processing, and machine learning into the software radio domain. The inter-disciplinary nature of cognitive radio raises interesting questions for future research and development. 10
  11. 11. THE RADIO spectrum, which is needed for wireless communication systems, is a naturally limited resource. To support various wireless applications and services in a noninterfering basis, the fixed spectrum access (FSA) policy has traditionally been adopted by spectrum regulators, which assign each piece of spectrum with certain bandwidth to one or more dedicated users. By doing so, only the assigned (licensed) users have the right to exploit the allocated spectrum, and other users are not allowed to use it, regardless of whether the licensed users are using it. With the proliferation of wireless services in the last couple of decades, in several countries, most of the available spectrum has fully been allocated, which results in the spectrum scarcity problem. On the other hand, recent studies on the actual spectrum utilization measurements have revealed that a large portion of the licensed spectrum experiences low utilization. These studies also indicate that it is the inefficient and inflexible spectrum allocation policy that strongly contributes to spectrum scarcity and, perhaps, even more than the physical shortage of the spectrum. To maintain sustainable development of the wireless communication industry, novel solutions should be developed to enhance the utilization efficiency of the radio spectrum.  Dynamic spectrum access (DSA) : has been proposed as an alternative policy to allow the radio spectrum to more efficiently be used . In DSA, a piece of spectrum can be allocated to one or more users, which are called primary users (PUs); however, the use of that spectrum is not exclusively granted to these users, although they have higher priority in using it. Other users, which are referred to as secondary users (SUs), can also access the allocated spectrum as long as the PUs are not temporally using it or can share the spectrum with the PUs as long as the PUs’ can properly be protected. By doing so, the radio spectrum can be reused in an opportunistic manner or shared all the time; thus, the spectrum utilization efficiency can significantly be improved. To support DSA, SUs are required to capture or sense the radio environment, and a SU with such a capability is also called a cognitive radio (CR) or a CR user. There are different types of cognitive capabilities with which a CR may 11
  12. 12. be equipped. For example, a CR may sense the ON/OFF status of the PUs or can predict the interference power level that is received at the primary receiver (Rx). In an extreme case, if a CR is a genie user, it may also acquire the messages that are transmitted by the primary Tx .The process of acquiring the radio environment knowledge can be complex and expensive, because it may involve spectrum sensing, autonomous learning, user cooperation, modeling, and reasoning. HISTORY AND BACKGROUND COGNITIVE RADIO: LEADING TO The sophistication possible in a software-defined radio (SDR) has now reached the level where each radio can conceivably perform beneficial tasks that help the user, help the network, and help minimize spectral congestion. Radios are already demonstrating one or more of these capabilities in limited ways. A simple example is the adaptive digital European cordless telephone (DECT) wireless phone, which finds and uses a frequency within its allowed plan with the least noise and interference on that channel and time slot. Of these capabilities, conservation of spectrum is already a national priority in international regulatory planning. This book leads the reader through the technologies and regulatory considerations to support three major applications that raise an SDR’s capabilities and make it a cognitive radio: 1. Spectrum management and optimizations. 2. Interface with a wide variety of networks and optimization of network resources. 3. Interface with a human and providing electromagnetic resources to aid the human in his or her activities. Many technologies have come together to result in the spectrum efficiency and cognitive radio technologies that are described in this book. This chapter gives the reader the background context of the remaining chapters of this book. These technologies represent a wide swath of contributions upon which cognitive technologies may be considered as an application on top of a basic SDR platform. To truly recognize how many technologies have come together to drive cognitive radio techniques, we begin with a few of the major contributions that have led up to today’s cognitive radio developments. The development 12
  13. 13. of digital signal processing (DSP) techniques arose due to the efforts of such leaders as Alan Oppenheim , Lawrence Rabiner, Ronald Schaefer Ben Gold, Thomas Parks [4], James McClellen James Flanagan , Fred Harris , and James Kaiser. These pioneers2recognized the potential for digital filtering and DSP, and prepared the seminal textbooks, innovative papers, and breakthrough signal processing techniques to teach an entire industry how to convert analog signal processes to digital processes. They guided the industry in implementing new processes that were entirely impractical in analog signal processing. Somewhat independently, Cleve Moler, Jack Little, John Markel, Augustine Gray, and others began to develop software tools that would eventually converge with the DSP industry to enable efficient representation of the DSP techniques, and would provide rapid and efficient modelling of these complex algorithms . Meanwhile, the semiconductor industry, continuing to follow Moore’s law ,evolved to the point where the computational performance required to implement digital signal processes used in radio modulation and demodulation were not only practical, but resulted in improved radio communication performance, reliability, flexibility, and increased value to the customer. This meant that analog functions implemented with large discrete components were replaced with digital functions implemented in silicon, and consequently were more producible, less expensive, more reliable, smaller, and of lower power . Defining the PDR, SDR, and Software Radio Military radios for mobile ground, air and naval applications employ the bands HF through UHF. Thus, 2 MHz to 2 GHz defines the nominal RF coverage of the tactical military radio. Commercial mobile radios typically do not require the HF band, but emphasize the mobile satellite, cellular and PCS bands between 400 and 2400 MHz instead. In the limit, an ideal mobile military software radio digitizes 2.5 GHz of RF, sampling at 6 gigasamples per second (gsps) with at least 60 dB of dynamic range, including the contributions of automatic gain control (AGC). The state of the art is 6 gsps and 30 dB .In addition, the 6 gsps DACs and filters cannot yet reach the spectral purity needed for the ideal software radio. With today’s technology, then, one must compromise the ideal, implementing programmable digital radios (PDRs), also called software-defined radios 13
  14. 14. (SDR). An SDR, for example, might use a fast tuning synthesizer to hop a 3 MHz instantaneous baseband bandwidth over a 200 MHz agility bandwidth. Although the pattern of hops generated by the synthesizer could be programmable, the instantaneous waveform bandwidth is limited to 3 MHz. A software radio, on the other hand, would digitize the 200 MHz bandwidth at 400 msps or more. The instantaneous bandwidth of the waveform, then, could be programmed to any bandwidth up to 200 MHz, not limited by the 3 MHz baseband. The PDR would have a programmable choice of hopping frequencies across 200 MHz, while the software radio would have an arbitrarily programmable waveform across the 200 MHz1. The degree of flexibility of a radio platform is of considerable relevance to cognitive radio. A commercially viable SDR may be implemented as a mix of Application-Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), Digital Signal Processors (DSPs), and generalpurpose microprocessors. ASIC parameters also may be defined in software. But, an ideal software radio has no ASICs. Instead, it implements all the radio’s RF conversion, filtering, modem and related functions in software. Implementation points A through D in the figure are contemporary SDRs. The Virtual Radio, however, is an ideal single-channel narrowband software radio based on a general-purpose processor, specifically a DEC Alpha, running UNIX. Point X is the ideal software radio with digital access at RF and all functions programmed in general purpose processors. Although providing maximum flexibility and thus of research interest, such designs are economically impractical in the short term. Cognitive radio’s focus, however, is on the fourth generation of wireless in which commercial radios will begin to approximate the software radio. 14
  15. 15. Fig 1. Dimensions of Software Radio Implementations . In the commercial sector, for example, a dual antenna-RF stage could cover the radio spectrum from 350 MHz to 2400 MHz. With a 100 MHz x 16 bit ADC and a few GFLOPS of processing capacity, this would be a powerful software radio precursor. Modelling the Software Radio The architecture-level model of identifies the functional components and interfaces of the software radio In order to reason about its own internal structure, a radio requires some such model. Cognitive radio’s internal model of itself is based on this specific model. 15
  16. 16. There are, however, many other comprehensive, precise models of the internal architecture of a radio. The architecture model of the SDR Forum, for example, augments the modem function with a data processing function on the channel coding and decoding side of the INFOSEC module. In addition, their model has no IF Processing module. One can create a mapping among the two models that establishes their equivalence. The appendix develops a topological model within which such mappings may be analyzed. That analysis includes the question of constraints on computational resources in software radio. Computational Resources Software radio includes the downloading of software objects that modify or extend the host radio’s capabilities. The SDR Forum, for example, has defined a secure download protocol that assures the object is suited to the host radio, appropriately authorized, and free of error . The thinking is that a new well-behaved object that interacts with existing well-behaved objects in the radio will yield a well-behaved system. Appendix B addresses the question “under what conditions can well-behaved radio software be composed with other well-behaved radio software to yield a well-behaved system?” This general question of software composition is known to be undesirable. That is, there is no algorithm that can examine two arbitrary pieces of software in finite time and yield “Yes” if they will yield an answer and “No” if they will consume infinite resources (and thus yield no answer). Fortunately, software radios are engineering systems with timing constraints that allow one to prescribe constraints on the topological 16
  17. 17. structure of the software that establishes conditions under which composition of software modules is well behaved [139]. Since modems, equalizers, vocoders, and other radio functions are part of an isochronous stream, they must run-to-complete in a short time window that a radio engineer can bound tightly in advance. There are therefore a-priority bounds on time and space (i.e. memory) for SDR modules that each new module must meet as well. Theoretically, these bounds comprise a step-counting function, a function that counts resources used by another program. There are programming constructs that will meet these bounds sometimes, but not for all possible circumstances. In particular, any construct that is equivalent to a while or until loop can cause two well-behaved software modules (or objects) to consume infinite resources in unpredictable ways. These functions will consume up to a specified amount of memory and time independently and up to another specified amount in concert. The theorems of the appendix show that the bounded recursive functions are the largest set of functions for which predictably finite resource consumption may be guaranteed. In addition, the composition of bounded recursive functions is also bounded recursive, and this sets measurable conditions under which plug-and-play modules will not use excessive resources. Furthermore, there is no practical limit on the useful radio functions that can be computed with the bounded recursive functions. Basic concept of cognitive radio  Background of cognitive radio : We have been living in a society where people can access anything, anywhere, anytime through networks regardless of time and location for the past 10 years, and consequently, multimedia communications by means of compact mobile terminals have gained popularity. Concurrently, the communication rates and other requirements for wireless communications have dramatically extended. These requirements will increasingly expand, and to meet them, a wide variety of high-speed wireless systems have been developed. With growth of mobile communications, frequency assignments are getting difficult; particularly in the frequency bands from VHF to 6 GHz suited for mobile 17
  18. 18. communications. It has become very difficult to allocate new frequencies for new wireless services. To solve the problem, research and development efforts to realize the cognitive radio technologies are being carried on.  Basic concept of cognitive radio : Cognitive radio is a radio system that senses, and recognizes operational communication environments and can dynamically and autonomously adjusts its radio operating such parameters as frequency, transmission power and data rates without interferences to other systems. Accordingly, a user can establish communications with required capacity and quality. Above Figure shows a conceptual image of a cognitive radio terminal. In the Above Figure, we assume that a mobile user is going to use a cognitive mobile phone. There are several communication services such as IEEE802.11g (Wi-Fi, 2.4 GHz), 3G cellular (2 GHz) and IEEE 802.16e (WiMAX, 2.5 GHz) in the communication environment. There is also a low interference to the WiMAX systems. 18
  19. 19.  The procedure of a cognitive terminal to establish a communication channel consists of following three steps. 1. The first step: Recognition of frequency environments. A cognitive terminal will sense communication environments and detect frequencies which are in use or not in use. A terminal has to scan wide frequency bands, which cover possible communications in services. 2.The second step: Think and decision According to the results of recognition of environments, a terminal has to decide and select a system based on a policy such as communication costs, data speed, communication quality and /or mobility. In any cases, a terminal or a base station has to select a system and a channel, which avoids interferences to and from other systems. 3. The third step: Change function of spectrum managements A terminal selects the optimal system or a user will select her favourite system from the menu to change the function to establish communication channels of the selected system, which procedure is called reconfiguration. Cognitive radio technology is to make frequency use more efficient and to make services more high quality by recognizing radio environments near the user terminal. Two types of cognitive radio and cognitive radio network 1. Heterogeneous type : Cognitive radio technologies can be divided into two types as shown in Figure . A heterogeneous type aims at the connection with existing radio system that is assigned with a dedicated frequency band, so that it can positively use a radio system having surplus wireless resources or select a radio system in accordance with the user's purpose to implement desired communications. 19
  20. 20. 2. Spectrum sharing type : On the other hand, the method to use vacant frequency bands is called spectrum sharing type (or white space type) cognitive radio. In spectrum sharing type, vacant frequency bands include vacant bands and vacant time slots of existing systems (primary operators) as well as vacant bands not in use. By sensing vacant frequency band and time slot, users can use adequate bandwidth by bundling vacant frequency bands. In operating spectrum sharing type cognitive radios, cooperation with networks are essential in order to coexist with the system which is serviced by a primary operator 20
  21. 21. Configuration of cognitive radio network When a cognitive radio technology is applied to heterogeneous (consists of different systems) wired networks, an ideal cognitive wireless network can be established where terminals, base stations, and wireless access network can be selected or reconfigured with optimum performance. As shown in Figure- 4-2, in a cognitive wireless network, the measured data of terminals and base stations are reported to the core network, and by conducting the statistic processing and machine learning on the part of the core network, reconfiguring requests for the operating frequencies and communication systems can be issued to the radio access network (RAN). Additionally, the network policy for supporting the terminals to select the RAN and base station is provided from the network. 21
  22. 22. Key technologies  Hardware platform : Figure- shows a typical configuration of a cognitive terminal consisting of hardware devices such as an antenna, filters, amplifiers, mixer, a synthesizer, analogue-digital (A/D) and D/A converters and signal processors. In order to scan wide frequency bands which cover many communication services in operation, a cognitive radio requires a broadband RF (radio frequency) unit, especially from VHF (30-300 MHz) up to 6GHz. Some devices such as antennas and mixers are simply but very difficultly required to cover these wide frequency bands. However, such devices as filters and amplifiers are required not only broadband but also “tunable” to a certain bandwidth suitable for sensing a desired system over VHF-up to 6GHz. From this point, intelligent filter-banks to sense existing radio communication systems are essential.  Software platform : In order to sense, detect and reconfigure the radio system, a software algorithm plays very important role in the cognitive radio. As a basic software platform (radio reconfiguration manager), the following factors are required : • Work on the several CPUs 22
  23. 23. • Equip an open access point interface (API) • Easily changeable parameters for spectrum sensing • Equip arranged profiling procedure • Block all of attacks for the waveforms (virus) The core and essential parts of software of cognitive radio function are the following software algorithms order to realize the optimum communication links for users and systems. • The fast selection and decision of the system, • A high-speed system-sensing algorithm • A high response reconfiguration algorithm for terminals and base stations and • Network system architectures, which can perform the resource managements cooperation with terminals, base stations and networks Research Agenda for Cognitive Radio Networks By their very nature, DSA and CRNs spans a range of disciplines. The physical layer involves high performance radio frequency circuits. We need to control and manage those circuits to gain flexibility and new capabilities. Once out of the analog domain, we need to analyze and process received communication signals. We need to limit bandwidth, be efficient in our utilization of radio frequency spectrum, deal with differences between the transmitter and receiver, handle radios in motion, adapt for the physical communications from the transmitter to the receiver, allocate radio resources for efficient communications, learn how and when to share information, re-route network traffic as links go up and down, and know how to adapt to the current situation in this complex radio communications environment. Wireless networks are challenging systems because of the complex nature of signal propagation. DSA further exacerbates those problems since spectrum use is even more dynamic and unpredictable. Cognitive networking research is inherently a multidisciplinary endeavour that must address not only traditional wireless networking challenges, but also the rational control and management of the spectrum, a distributed and dynamic resource, which raises complex policy and economic issues. 23
  24. 24. 24
  25. 25. Cognitive Networks and the Internet The research questions and answers essential to building cognitive radio networks are, in some sense, extreme problems of wired networks. For example, both wired and wireless networks need to deal with links going up and down. However, in the wireless network, the frequency of link status changes is much higher than in today’s wired network. So, wireless network architectures must pay closer attention to link status changes and react faster to these changes. Research in CR networks will carry over into wired network.  Some characteristics of cognitive radio networks that are applicable to larger, end-to-end network are: • Operating environment sensing – Cognitive radios measure and react to the environment they are operating in. The radio environment is multi-dimensional; including cooperative and noncooperative emitters turning on and off, CRs adapting to their local changes, and traffic loads; and rapidly varying. CRs must rapidly adapt to this changing environment and communicate their changing operation settings to other wireless devices in the network. The mechanisms and Future Directions in Cognitive Radio Network Research Page: 18 NSF Workshop Report June 2009 techniques to sense, adapt, and communicate operation state are necessary in CR networks and applicable to networks in general. • Robust communication services with unreliable links – The radio links, by their very nature, have intermittent outages. A link outage may result from the temporary location of the receiver, transmitter and other objects in the environment. CRs, by their very design, must deal with these very short-term link outages, and do so through a variety of techniques. It is through this large set of techniques and mechanisms that wireless networks implement a robust and reliable communications service with unreliable links. The techniques and design patterns used in wireless architectures are applicable to the larger network architecture. • Operational state languages – CRNs, as they adapt, must communicate their observations and operation state to other CRNs in the network. A few “languages” will be needed to describe observations and operation state. This information is likely to be much richer than common link status information. For example, one radio might send a list of all emitters it has 25
  26. 26. recently sensed to other CRNs in the network. The entry for each emitter might include a frequency range, time, and spatial location, and signal format (e.g., spread spectrum or narrow-band FM). The language used to describe observations and operation state will be much richer than conventional node or link state information. The language(s) and protocols necessary for CRN networks should influence general network architectures. • Distributed Resource Management – The radio spectrum is a distributed resource. Use of the spectrum in one location affects the availability of that spectrum in other network locations. Allocation of the radio spectrum resource must be carried out in a cooperative manner and balanced between (quick) local decisions and (optimal) global allocation. The algorithms developed to allocate the distributed radio spectrum and mobile network resources based on traffic loads and operating environment are applicable to the GENI infrastructure – and will require demanding new services within the GENI network. These examples show how techniques and mechanisms necessary to CR networks will have an influence on the architecture, design and implementations of networks in general. FEATURES OF COGNITIVE RADIO : Some features of cognitive radio networks include: • Sensing the current radio frequency spectrum environment: This includes measuring which frequencies are being currently used, estimating the location of transmitters and receivers, and determining signal modulation. These results are then used to determine the radio settings. • Policy and configuration databases: This includes having knowledge of the policies that specify how the radio can operate and physical limitations of radio operation. This information can be stored in the radio or made available over the network. The policies might also specify which frequencies are licensed to be used in which locations. Configuration databases would describe the operating characteristics of the physical radio. These databases would normally be used to constrain the operation of the radio to stay within regulatory or physical limits. • Re-configuration: 26
  27. 27. Dynamically programmable capability according to radio environment to transmit and receive on a variety of frequencies i.e. the radio can automatically change its parameters so as to work on different frequencies. • Mission-oriented configuration : Software defined radios can meet a wide set of operational requirements. Configuring a SDR to meet a given set of mission requirements is called mission oriented configuration. Typical mission requirements might include operation within buildings, substantial capacity, operation over long distances, and operation while moving at high speed. Mission-oriented configuration involves selecting a set of radio software modules from a library of modules and connecting them into an operational radio. • Adaptive algorithms : During radio operation, the cognitive radio is sensing its environment, adhering to policy and configuration constraints, and negotiating with peers to best utilize the radio spectrum and meet user demands. • Distributed collaboration: Cognitive radios will exchange current information on their local environment, user demand, and radio performance between themselves on a regular basis. Radios will use their local information and peer information to determine their operating settings. •Security: Radios will join and leave wireless networks. Radio networks require mechanisms to authenticate, authorize and protect information flows of participants. CRNs operate in a rich environment. The agility of underlying SDR platforms provides a level of flexibility well beyond conventional radio and networking platforms. SPECTRUM HOLE CONCEPT A spectrum hole is a band of frequencies assigned to a primary user, but, at a particular time and specific geographic location, the band is not being utilized by that user. A region of location-time frequency available for a secondary user is called a spectrum hole (SH). Generally, a CR system is able to coexist with a primary system by accessing SHs. Apparently, SH is a basic 27
  28. 28. . resource for CR users. FUTURE APPLICATIONS : Cognitive radio technology can be used in a variety of applications in the future which include• 4G technology - which aims at achieving very high data transmission rate. For high rate larger bandwidth should be available so that more channels can be accommodated within the system. However since the frequency spectrum is limited this is not possible. CR approach allows accessing the under utilized spectrum in the licensed bands and hence improving efficiency. • Cellular networks: With increase in the number of mobile phone users which are expected to rise further in future there will be heavy traffic on the network and hence jamming can occur. Hence CR technology can provide a solution for this. 28
  29. 29. • Vehicular Communication: In the vehicular domain, the CR could be used to enhance and improve intelligent interactions with the transportation system. Importantly, CR could be the driving force in order to realize real-time cooperative communications between the vehicles. This would eventually result in seamless vehicle-to-vehicle and vehicle-to-infrastructure communications, a gigantic step towards unified and continuous service provision involving variable speed vehicles. • Emergency network: In case of a disaster, the load on the network increases. This can be reduced if an alternate band is available to accommodate some of the users which can be achieved using CR. Conclusion The rapid development of wireless technologies is expected to increase the demand for radio spectrum by orders of magnitude over the next decade. This problem must be addressed via a technology that can result in improvement in spectrum efficiency and increase robustness and performance of wireless devices. Cognitive radio technology is one such innovation that could provide solutions to the “radio traffic jam” problem and provide a path to scaling wireless systems for the next 25 years. Cognitive radio technology can be used in a variety of applications in the future which include• • • • 4G technology Cellular Networks Vehicular Communication Emergency network However there are a lot of technical challenges in cognitive radio networking. These include dynamic spectrum allocation methods, spectrum sensing, cooperative communications, cognitive network architecture and protocol design, cognitive network security, cognitive 29
  30. 30. system adaptation algorithms and emergent system behaviour. A major hurdle to continued progress in the field is the inability to conclusively test, evaluate, and demonstrate cognitive networking technology, at scale and in real-world deployment scenarios. This calls for the development of a set of cognitive networking testbeds that can be used to evaluate cognitive networks at various stages of their development. Cognitive Radio Network applications : Cognitive Radio Networks can be applied to the following cases: 1. Leased network: The primary network can provide a leased network by allowing opportunistic access to its licensed spectrum with the agreement with a third party without sacrificing the service quality of the primary user. For example, the primary network can lease its spectrum access right to a mobile virtual network operator (MVNO). Also the primary network can provide its spectrum access rights to a regional community for the purpose of broadband access. 2. Cognitive mesh network: Wireless mesh networks are emerging as a cost-effective technology for providing broadband connectivity. However, as the network density increases and the applications require higher throughput, mesh networks require higher capacity to meet the requirements of the applications. Since the cognitive radio technology enables the access to larger amount of spectrum, CR networks can be used for mesh networks that will be deployed in dense urban areas with the possibility of significant contention. For example, the coverage area of CR networks can be increased when a meshed wireless backbone network of infrastructure links is established based on cognitive access points (CAPs) and fixed cognitive relay nodes. The capacity of a CAP, connected via a wired broadband access to the Internet, is distributed into a large area with the help of a fixed CRN. CR networks have the ability to add temporary or permanent spectrum to the infrastructure links used for relaying in case of high traffic load. 3. Emergency network: Public safety and emergency networks are another area in which CR networks can be implemented. In the case of natural disasters, which may temporarily disable or destroy existing communication infrastructure, emergency personnel working in the disaster areas need to establish emergency networks. Since emergency networks deal with the critical information, reliable communication should be 30
  31. 31. guaranteed with minimum latency. In addition, emergency communication requires a significant amount of radio spectrum for handling huge volume of traffic including voice, video and data. CR networks can enable the usage of the existing spectrum without the need for an infrastructure and by maintaining communication priority and response time. 4. Military network: One of the most interesting potential applications of an CR network is in a military radio environment. CR networks can enable the military radios choose arbitrary, intermediate frequency (IF) bandwidth, modulation schemes, and coding schemes, adapting to the variable radio environment of battlefield. Also military networks have a strong need for security and protection of the communication in hostile environment. CR networks could allow military personnel to perform spectrum handoff to find secure spectrum band for themselves and their allies. Summary Cognitive radio is an immature but rapidly developing technology area. In terms of spectrum regulation, the key benefit of CR is more efficient use of spectrum, because CR will enable new systems to share spectrum with existing legacy devices, with managed degrees of interference. There are significant regulatory, technological and application challenges that need to be addressed and CR will not suddenly emerge. Cognitive radio networks are being studied intensively. The major motivation for this is the currently heavily under utilized frequency spectrum. The development is being pushed forward by the rapid advances in SDR technology enabling a spectrum agile and highly conigurable radio transmitter/receiver. A fundamental property of the cognitive radio networks is the highly dynamic relationship between the primary users having an exclusive priority to their respective licensed spectrum and the secondary users representing the cognitive network devices. This creates new challenges for the network design which have been addressed applying varies approaches as has been discussed in the previous sections. The fundamental problems in detecting the spectrum holes are naturally mostly related to signal processing at the physical layer. From the traffic point of view careful attention must be 31
  32. 32. paid in order to guarantee an effcient usage of the wireless medium while simultaneously providing fairness between competing users and respecting the priority of the primary users 32

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