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Analysis of OSTBC in Cooperative Cognitive Radio Networks using 2-hop DF Relaying Protocol
Blekinge Institute of Technology, School of Engineering.
Blekinge Institute of Technology, School of Engineering.
Blekinge Institute of Technology, School of Engineering.
2011 (English)Independent thesis Advanced level (degree of Master (Two Years))Student thesis
Abstract [en]

To achieve cooperative diversity in cognitive radio network, Decode and Forward (DF) protocol is implemented at Cognitive Radios (CRs) using Orthogonal Space Time Block Coding (OSTBC). The 2-hop communication between source and destination is completed with the help of Cognitive Relays (CRs) using Multiple Input Multiple Output (MIMO) technology within the network. To achieve spatial diversity and good code rate Alamouti 2×2 STBC is used for transmission. CR is using the decoding (Decode and Forward (DF)) strategy and without amplifying ability before forwarding data towards destination provide better performance. The main objective of this thesis is to detect Primary User (PU) spectrum availability or non-availability for the use of Secondary Users (SU). The Alamouti STBC encoded data is broadcasted to wireless Rayleigh faded channel through transmitter having two transmitting antennas. The CRs are preferred to place close with PU to detect transmitted signal and because of having decoding capability CRs decode the collected data using Maximum Likelihood (ML) decoding technique then re-encode the decoded data for further transmission towards receiver. The energy of PU signal received at relays is calculated using energy detector used at cognitive controller having authority to make final decision about presence or absence of PU signal within the spectrum by comparing calculated energy of PU received signal with a predefined value. If the calculated signal energy is less than threshold value it is pretended as the absence of PU and in the other case spectrum is assumed as occupied by PU. Decoding PU signal at relays before forwarding towards destination provide better performance in terms of detection probability and decreasing probability of false alarming as the Signal to Noise (SNR) increases. The proposed cooperative spectrum sensing using DF protocol at cognitive relays with Alamouti STBC is implemented and results are validated by MATLAB simulation.

Place, publisher, year, edition, pages
2011. , 66 p.
Keyword [en]
Cognitive Radio, Cooperative Communication, Alamouti STBC, OSTBC, Rayleigh Fading, Energy Detector, DF Relay, Maximum Likelihood, MRC
National Category
Signal Processing Probability Theory and Statistics Telecommunications
URN: urn:nbn:se:bth-2510Local ID: diva2:829789
Physics, Chemistry, Mathematics
+46 455 38 50 00Available from: 2015-04-22 Created: 2011-06-30 Last updated: 2015-06-30Bibliographically approved

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