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Throughput Analysis of Secondary Users Cooperating with Primary Users in Wireless Networks

Nazari, Mohammad Ali | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44121 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ashtiani, Farid
  7. Abstract:
  8. Cooperative coexistence of two kinds of users with different priorities in random access wireless networks has been studied in this thesis. Source burstiness, a phenomenon in data communication networks, allows using silence periods of primary users (PUs) to have a better spectrum utilization. In this respect, new users, known as secondary users (SUs), are considered to exploit the resources opportunistically. In usual spectrum sharing systems, SUs have to act in a way to be transparent for the PUs. Therefore, they are allowed to access the common spectrum band only when PUs are silent. However, seeking such opportunities needs sensing capability of secondary nodes.In this thesis, sensing capability has not been considered for the SUs. They compete with other users randomly, without sensing and without any attention to transmission attemps of users, and just access with a lower priority. Obviously, the presence of SUs, in such a network, where PUs access the channel randomly as well, causes performance degradation for primary users. To lessen the adverse effect caused by presence of SUs, relaying capability is proposed to be considered for SUs. In fact, each SU sends its packets as well as the primary packets collided at the access point, but overheard successfully at the SU, by random access the primary WLAN. In this thesis, cooperative coexistence of PUs and SUs considering different transmission protocols for SUs, are investigated. To this end, we use an analytical model based on open queueing networks. To compare, we evaluate the stability region, traffic intensity of users and the PUs QoS provisioning region as the performance metrics of the proposed protocols. According to the analytical and simulation results for the scenario of this thesis, it is interesting to say that for some values of PUs arrival rates, in some cooperative protocols, we are even able to decrease the traffic intensity of PUs, while the network throughput has been increased
  9. Keywords:
  10. Cooperative Network ; Random Access ; Queueing Network ; Primary Users ; Stability Region ; Secondary Users

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