Presentation on SPECTRUM SHARING IN COGNITIVE RADIO NETWORK Made By: NIVEDITA CHANDRAKANT AHIRE
AGENDA • HISTORY • INTRODUCTION • DEFINITION • COGNITVE RADIO • COGNITIVE RADIO ARCHITECTURE • FUNCTIONALITIES OF CRN • SPECTRUM SHARING IN COGNITIVE RADIO NETWORKS • CLASSIFICATIONS • INTER NETWORK SPECTRUM SHARING • INTRA NETWORK SPECTRUM SHARING • REFERENCES • CONCLUSION
HISTORY • Proposed by Dr. Joseph Mitola in 1999
WHY COGNITIVE RADIO ? • Current wireless networks are regulated by fixed spectrum assignment policy • According to Federal communication commission , temporal and geographical variations in the utilization of the assigned spectral ranges from 15% to 85% .
WHY COGNITVE RADIO ? Fixed Spectrum Assignment policyWhite Spaces Inefficient spectrum utilization Cognitive radio network : It is a new paradigm that provides the capability to share or use the spectrum in an opportunistic manner.
COGNITIVE RADIO • Cognitive radio is a wireless communication system which is aware of the environment and its changes and can adapt its transmission parameters accordingly. • Cognitive Capability: The ability to sense the unused spectrum at a specific time and location (spectrum hole)
Continued…. Reconfigurability: The ability to receive and transmit at different frequency band enables the cognitive radio to reconfigure its parameters and select the best band.
COMPONENTS OF CRN • PRIMARY NETWORK • Primary Users: • Primary users have the license to operate in certain spectrum bands • Primary base station: • Controls the access of primary users to spectrum • SECONDARY NETWORK • Secondary Users: • Secondary users have no licensed bands assigned to them. • Secondary base-station: • A fixed infrastructure component with cognitive radio capabilities and provides single hop connection to secondary users. • Spectrum broker : • Scheduling server shares the spectrum resources between different cognitive radio networks.
NETWORK ACCESS TYPES CR Network Access: CRs can access their own base station on both licensed and unlicensed spectrum bands CR Ad Hoc Access: CRs can communicate with other CRs through an ad hoc connection on both licensed and unlicensed spectrum bands. Primary Network Access : CRs can access primary base station through the licensed bands.
FUNCTIONALITY OF CRN Spectrum Sensing: This function detects spectrum holes and senses the presence of the LU when the CU operates on a licensed band. Spectrum Management: Based on the availability of the spectrum and other policies, CR user allocates the best available spectrum band. Spectrum Mobility: CR user shall vacate the spectrum in the presence of any primary user and move to next best available spectrum band Spectrum Sharing: CR network has to provide a fair and optimal spectrum allocation method among multiple CR users.
FUNCTIONS OF NETWORK LAYER • Physical layer: • spectrum sensing • data reconfigurable transmission based on Software Defined Radio (SDR). • Link Layer : • spectrum analysis • spectrum selection(spectrum adjustment) • spectrum coordination.
FUNCTIONS OF NETWORK LAYER • MAC layer: • Obtaining information on channel occupancy. • Performing negotiation among primary users and secondary users for spectrum allocation and also among secondary users for channel sensing and access. • Synchronizing transmission parameters (e.g. channel, time slot) between transmitter and receiver. • Facilitating spectrum trading functions (e.g. spectrum bidding and pricing).
APPLICATIONS OF CRN Leased network Cognitive mesh network Emergency network Military network
SPECTRUM SHARING • Spectrum sharing is the simultaneous usage of a specific radio frequency band in a specific geographical area by a number of independent entities, leveraged through mechanisms other than traditional multiple- and random-access techniques. The spectrum sharing process consists of five major steps: • Spectrum sensing:detects spectrum holes and senses the presence of the LU when the CU operates on a licensed band. • Spectrum allocation: Allocation of a channel not only depends on spectrum availability but also depends on internal and external policies.
SPECTRUM SHARING • Spectrum access: Since there are multiple secondary users trying to access the spectrum, their access should be coordinated to avoid colliding in overlapping portions of the spectrum. • Transmitter-receiver handshake: After deciding a portion of the spectrum, the receiver of this communication should also be indicated. • Spectrum mobility: If the specific portion of the spectrum is needed by a licensed user, the communication needs be continued in another vacant portion.
CLASSIFICATION • Classification based on Architecture. 1.Centralized Spectrum Sharing. 2.Distributed Spectrum Sharing. • Classification based on access behaviour. 1.Cooperative Spectrum Sharing 2.Non Cooperative Spectrum Sharing • Classification based on access technique.
CLASSIFICATION BASED ON ACCESS BEHAVIOUR Overlay Spectrum Sharing
CLASSIFICATION BASED ON ACCESS BEHAVIOUR Underlay Spectrum Sharing
INTER NETWORK SPECTRUM SHARING Centralized Inter-Network Spectrum Sharing
INTER NETWORK SPECTRUM SHARING Distributed Inter-Network Spectrum Sharing
INTRA NETWORK SPECTRUM SHARING 1.Centralized Intra-Network Spectrum Sharing
INTRA NETWORK SPECTRUM SHARING 2.Distributed Intra-Network Spectrum Sharing
CHALLENGES • Common Control Channel(CCC) • Uses spectrum sharing functionalities. • In feasible in xG networks. • Dynamic Radio Range • Radio range changes with operating frequency due to attenuation variation. • Neighbours of a node may change as the operating frequency changes. • Select control channels in the lower portions of the spectrum where the transmission range. • Select data channels in the higher portions of the spectrum.
CONCLUSION • Solve the current existing problems in wireless communications • Dynamic spectrum sharing is being used. • Efficient Spectrum sharing. • Spectrum sharing can be performed over licensed or unlicensed bands • Unlicensed bands allow systems/devices to utilize those bands without requiring a spectrum license
REFERENCES IEEE Papers: H. Feizresan and Dr. M. J. Omidi “Spectrum Sharing in Cognitive Radio Networks” (Electrical and Computer Engineering Department, Isfahan University of Technology) VarakaUdayKanth, Kolli Ravi Chandra , Rayala Ravi Kumar ,Associate professor, Dept. of ECE KL University “Spectrum Sharing in Cognitive Radio Networks” in (IJETT) - Volume4Issue4- April 2013 Beibei Wang and K. J. Ray Liu “Advances in Cognitive Radio Networks: A Survey” IEEE Journal Of Selected Topics In Signal Processing, Vol. 5, No. 1, Feburary 2011 WORD WIDE WEBS: • www.cs.umd.edu/~jkatz/THESES/clancy.pdf by TC Clancy III -2006 • newport.eecs.uci.edu/ • ieeexplore.ieee.org • www.researchgate.net/…Spectrum_sharing_in_cognitive_radio_networks by HB Salameh