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Impact of Cognition and Cooperation on MAC Layer Performance Metrics

Sharifi Noori, Ali Asghar | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39913 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ashtiani, Farid; Nasiri-Kenari, Masoumeh
  7. Abstract:
  8. In this thesis, we study the effect of cognition and cooperation on two important MAC layer performance metrics, i.e. maximum stable throughput and delay. To this end, we consider a broadband secondary user which interferes with N narrowband primary users. In our study we focus on four transmission protocols as well as two transmission policies, i.e. parallel and non-parallel transmissions. In the cooperative protocols, the broadband transmitter relays the packets of the primary users which have not correctly decoded at the primary receiver. In non-parallel transmission case, the packets of the broadband user are transmitted in the total available bandwidth and in parallel transmission case, the broadband user transmits packets in its available subbands simultaneously and as several independent parts. Moreover, we analyze these protocols in two fading channel types, i.e. flat fading and frequency selective fading. The analysis includes random packet arrivals of the transmitters which may impact on the MAC layer performance metrics. Moreover, sensing errors at the secondary user are considered. The results reveal that the cooperative protocols provide significant performance gains over non-cooperative protocols, especially at active primary users regimes. Moreover, cognition results in a significant improvement on the broadband user’s throughput. Numerical results indicate that in the frequency selective channel, the parallel transmission is preferred, while in the flat fading channel, there is no considerable difference between two transmission policies.

  9. Keywords:
  10. Stability Analysis ; Delay Function ; Queueing System ; Media Access Control (MAC)Layer ; Orthogonal Frequency Division Multiplexing (OFDM) ; Fading Channel ; Frequency Selective Fading Channel ; Cognitive Radio ; Cooperation Communication

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