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    by: er.naveenmaurya

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    1 : Presented By: NAVEEN MAURYA (ECE/08/1526) 1 Cognitive Radio Networks
    2 : What is a cognitive radio? Motivation for using “cognition” in IEEE 802.22 Systems Window of Opportunity Characteristics of cognitive radio system Cognitive Engine Architecture Classification of Cognitive radio networks From WiFi to Cognitive Radios Application Scenarios Refrences 2 Outline
    3 : What is a cognitive radio? An enhancement on the traditional software radio concept wherein the radio is aware of its environment and its capabilities, is able to independently alter its physical layer behavior, and is capable of following complex adaptation strategies. Cognitive radio Cognition cycle
    4 : Motivation for using “cognition” in IEEE 802.22 Systems Using previous experience to predict: Channel reputation Incumbent detection Other patterns Protect incumbent users by being aware of the environment Co-existence and self co-existence Spectrum utilization improvements Future proofing for other CR technologies “It is not known whether a CR network can offer satisfactory performance despite the injection of many new incumbent handling mechanisms…” [Cordeiro, et. al. 2005]
    5 : Window of Opportunity Time (min) Frequency (Hz) Existing spectrum policy forces spectrum to behave like a fragmented disk Bandwidth is expensive and good frequencies are taken Unlicensed bands – biggest innovations in spectrum efficiency Recent measurements by the FCC in the US show 70% of the allocated spectrum is not utilized Time scale of the spectrum occupancy varies from msecs to hours
    6 : - A software-defined radio with some artificial intelligence to make detection and wise decision according to its environment 6 Fig 1: An example of cognitive radio system components Example of cognitive
    7 : Cognitive capability Ability to capture or sense the information from its radio environment and allows to identify and select the portion of the spectrum that are unused at a specific time or location. Reconfigurability Dynamically programmable capability according to radio environment to transmit and receive on a variety of frequencies. 7 Characteristics of Cognitive Radio System
    8 : Cognitive Radio is a promising tool for… Access to spectrum finding an open frequency and using it Interoperability talking to legacy radios using a variety of incompatible waveforms Cognitive Radio Platform
    9 : Cognitive Engine Architecture
    10 : Cognitive Engine Modules Sensing Module – provides radio environment sensing results REM – provides a snapshot of the radio scenario through time Main Controller – decides which algorithm to use Case and Knowledge Reasoner – provides coarse solution, starting point for the Multi-objective Optimizer Multi-objective Optimizer – further refines the solution obtained by the CBR
    11 : Spectrum management functions necessary for adapting to dynamic spectrum environment from a cognitive cycle as shown below: 11 Cognitive cycle Fig. 8 Cognitive cycle
    12 : Infrastructure based CR networks Has a central network entity to coordinate communication such as base station in cellular networks and access point in wireless LANs. 12 Classification of CR networks An example of infrastructure based CR networks
    13 : Cognitive radio ad hoc networks(CRAHNs) Infrastructure less network Does not have a central network entity A CR user can communicate with other CR users through ad hoc connection on both licensed and unlicensed spectrum bands. 13 …continue classification An example of CRAHNs
    14 : From WiFi to Cognitive Radios
    15 : Application Scenarios Licensed network Secondary markets Third party access in licensed networks Unlicensed network Cellular, PCS band Improved spectrum efficiency Improved capacity Public safety band Voluntary agreements between licensees and third party Limited QoS TV bands (400-800 MHz) Non-voluntary third party access Licensee sets a protection threshold Automatic frequency coordination Interoperability Co-existence ISM, UNII, Ad-hoc
    16 : [1] “Cognitive Radio Ad Hoc Networks” 7 (2009) 810-836, Ian F. Akyildiz , Won-Lee, Kaushik R. Chowdhury [2] Akyildiz, I.F.; Won-Yeol Lee; Vuran, M.C.; Mohanty, S. “A Survey on Spectrum Management in Cognitive Radio Networks” communications magazine, IEEE, vol. 46, Publication Year: 2008 , Page(s): 40 - 48 [3] Akyildiz, I.; Won-Yeol Lee; Chowdhury, K. , “Spectrum Management in Cognitive Radio Ad Hoc Networks” Network ,IEEE, Volume: 23, Publication Year: 2009 , Page(s): 6 - 12 16 References
    17 : Thank You! 17

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