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Error Rate Analysis and Power Allocation for Cooperative Networks with Imperfect Channel State Information

Razavi, Ali | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42700 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Pakravan, Mohammad Reza
  7. Abstract:
  8. Recently, cooperative communications have gained much interest due to its ability to mitigate fading in wireless networks through achieving spatial diversity while resolving the difficulties of installing multiple antennas on small communication terminals. There have been considerable research efforts on the performance analysis of cooperative diversity. This is while most of the current works assume that perfect knowledge of the channel information is available at the destination and/or relay terminals. However, in many practical scenarios, due to the errors caused by Doppler shift or noise on the pilot signals the perfect estimation of channel coefficients is not possible. In this thesis, we have first modeled the transmission scheme and the channel estimation error. The utilized model accounts for the transmission of the pilot symbols and demonstrates the transmission power dependent characteristic of estimation error. Then the Symbol Error Rate (SER) has been chosen as the performance metric and calculated for Amplify and Forward (AF) and Decode and Forward (DF) relaying protocols and PSK and QAM modulation types, with two different approaches. In the first approach no approximation is used and the exact SER is derived. However this expression has not a mathematically traceable form and doesn’t lead to a good intuition about the system performance. Considering some simplifying assumptions, a closed form solution is derived in the second approach which is in a good agreement with the first approach especially in the average to high Signal to Noise Ratio (SNR) regime. Also we have developed a novel power allocation between source and relay and in the data and pilot symbols transmission phases which minimizes SER with a total power constraint or equivalently minimizes total consumed power with a SER constraint
  9. Keywords:
  10. Power Optimization ; Cooperative Diversity ; Amplify-and-Forward ; Decode and Forward ; Symbol Error Rate

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