Cognitive Radio: Next Generation Communication System

1. Cognitive Radio: NextGeneration Communication System By V.ALAGU ABINAYA 11MCO02

2. Evolution of Communication Systems

3. Software Defined Radio Software Defined Radio as a basic platform on which to build a Cognitive Radio Cognitive Radio can provide the spectral awareness technology to support FCC initiatives in Spectral Use

4. Definition of SDR *Notice of Proposed Rule Making (NPRM) 8/12/00 • Software defined radios -evolutionary process from purely hardware-based equipment to fully software-based equipment. 1. Hardware driven radios-Transmit frequencies, modulation type and other radio frequency (RF) parameters are determined by hardware and cannot be changed without hardware changes. 2. Digital radios -A digital radio performs part of the signal processing or transmission digitally, but is not programmable in the field 3. Software Defined Radios- All functions, modes and applications can be configured and reconfigured by software • SDR Forum- - waveform properties, cryptography and applications, is re-programmable, and may be upgraded in the field with new capabilities - Importance of Standards (APIs)

5. Cognitive Radio

6. Spectrum Allocation

7. COGNITIVE RADIO • Two-way radio • Automatically changes its transmission or reception parameters • communicates efficiently, avoiding interference with licensed or licensed exempt users. • Monitoring of several factors in the external and internal radio environment -radio frequency spectrum, user behaviour and network state • FCC –Federal Communication Commission “A software defined radio with a cognitive engine brain".

8. Cognitive Radio Means “Smart” and “Alert • It knows where it is • It knows what services are • available, for example, it can identify then use empty spectrum to communicate more efficiently • It knows what services interest the user, and knows how to find them • It knows the current degree of needs and future likelihood of needs of its user • Learns and recognizes usage patterns from the user • Applies “Model Based Reasoning” about user needs, local content, environmental context

9. Need for Cognitive Radio • Radio spectrum is a scarce resource and is regulated • Spectrum usage is one of the key issues in communication system challenges • The spectrum efficiency can be improved with idea of dynamic spectrum allocation. • Cognitive radio network - on effective spectrum utilization -allocates to primary user or licensed user -user is not utilizing ,secondary user can claim without interfering to primary user

10. What is needed for a CR ?

11. Cognitive Radio Evolution

12. How Cognitive radio works? • Cognitive radio -Spectrum sensing -Spectrum management -Spectrum mobility -Spectrum sharing • awareness of changes in its environment • response to these changes adapts - operating characteristics - improve its performance or to minimize a loss in performance

13. External Intelligence Sources Orient Establish Priority Infer on Context Hierarchy Normal Plan Generate Alternatives (Program Generation) Evaluate Alternatives Pre-process Immediate Urgent Parse Register to Current Time Learn Observe New States Receive a Message Decide Read Buttons Save Global States Prior States Alternate Resources Outside World Act Initiate Process(es) (Isochronism Is Key) Send a Message Set Display The Cognition Cycle How Does a Cognitive Radio Get So Smart? Mitola, “Cognitive Radio for Flexible Mobile Multimedia Communications”, IEEE Mobile Multimedia Conference, 1999, pp3-10

14. Spectrum Sensing • Dynamic spectrum allocation • Cognitive radio networks – scans the entire spectral band for the presence/absence of primary users • Performed either locally - secondary user - collectively by a group Contd…

15. Contd… Spectrum Sensing • Transmitter detection- capability to determine if a signal from a primary transmitter is locally present in a certain spectrum. There are several approaches -Matched filter detection -Energy detection -Cyclostationary feature detection • Cooperative detection- information from multiple Cognitive radio users are incorporated for primary user detection. • Interference based detection

16. Spectrum Management • Spectrum Management - capturing the best available spectrum to meet user communication requirements • Decide on the best spectrum band -Quality of service • These management functions can be classified • spectrum analysis • spectrum decision • Practical implementation of functions - very complex and multifaceted issue in itself.

17. Spectrum Mobility • Spectrum Mobility- when a user exchanges its frequency of operation - use the spectrum in a dynamic manner with the best available frequency band - maintaining seamless communication requirements with better spectrum.

18. Spectrum Sharing • Spectrum Sharing – provides the fair spectrum scheduling method • One of the major challenges is spectrum sharing. • It can be regarded to be similar to generic media access control MAC problems in existing systems

19. The future of CR • The unlicensed band in range of wireless devices and services • FCC - consider opening further bands for unlicensed use. • Exploits the inefficiently utilized licensed bands without causing interference to incumbent users • Unlicensed radios to operate in the TV broadcast bands and also TV services.

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