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Evaluation of Rateless Coding on Relay Networks

Shirvani Moghaddam, Mahyar | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40970 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Hossein Khalaj, Babak
  7. Abstract:
  8. Fountain codes enable wireless networks to adapt their transmission rates to the state of the channels, without the need for channel state information (CSI) at the transmitters. According to the following properties of rateless codes, ever increasing parity generation, mutual information receiver, single bit feedback, and information combining receiver, they are good choice for relay networks. In this research, the design of rateless codes for wireless relay networks has been studied. Cross layer issues should be seriously considered when using rateless codes in the packet level. One cross-layer scheme has been developed in this thesis and analysis show that the performance of the proposed scheme is better than the case that we use rateless code on physical layer, in the sense of overall transmission time. It is important to note that rateless codes have been originally designed and optimized for erasure channels and so, using them in fading channels can lead to the significant performance degradation. Due to the fact that each node in a relay network can use separate rateless code, there are several transmission schemes for relay networks. Furthermore, at receiver, information combining and energy combining can be done. Mathematical analysis show that the overall transmission time for the case that relay nodes use different rateless codes is lower than the case that they use the same rateless codes. It is also possible that each relay node uses decode-forward or amplify-forward strategy. In this thesis, different rateless transmission schemes have been analyzed and it has been shown that the combined AF-DF strategy has better performance comparing with other existing methods.
  9. Keywords:
  10. Relay Channel ; Cross Layer Design ; Relay Network ; Rateless Codes

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