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Design of Adaptive Interleaver in Wireless Communication

Alidadi, Afsoon | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46752 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Golestani, Jamaloddin
  7. Abstract:
  8. Generally to deal with errors in communication systems, two methods have been proposed: FEC and ARQ. In FEC, redundancy bits are added to the data that causes detection and correction of certain error patterns. ARQ method is based on retransmission of information if there is an error in the information. Another method, which is called Hybrid-ARQ, is the combination of these two methods; there are two types of TypeI and TypeII for this category. In typeI, number of redundancy bits in consecutive transmissions of one codeword is constant but in typeII, number of redundancy bits of a codeword increases in subsequent retransmissions.
    To deal with burst errors, we can use interleaving along with error combating methods mentioned above. Using interleaving, from one side, breaks burst errors that reduces the codewords error rate. This reduction, in turn, leads to a reduction in the need for retransmission of the information in the ARQ process and reduces delay. But the interleaving intuitively creates an additional delay that is due to the gap in sending the bits of a codeword. The greater the interleaving depth, the greater this delay. So the interleaving depth can not be increased as desired and on the other hand if the depth is small, it does not have any effect on the codewords error rate.
    The purpose of this project is to implement an adaptive algorithm to find the appropriate interleaving depth based on the appropriate queue length, so that the appropriate integration to eliminate errors, on the one hand, and to avoid excessive delay in the transmission of information, on the other hand, is achieved. In this regard, the queueing model for the communications system is intended and for transmission of the information, composition of interleaving and method TypeI (of Hybrid-ARQ) is used
  9. Keywords:
  10. Queue Length ; Error Correction Codes ; Automatic Repeat Request (ARQ) ; Interleaving ; Burst Error

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