Butterfly-Flow-Graph Based MAP Decoding Algorithm for Channel Quality Information in 3GPP-LTE

  • Qi Li
  • He Wang
  • Yunchuan Yang
  • Bin Yu
  • Chengjun Sun
Conference paper
Part of the Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering book series (LNICST, volume 237)


Channel quality information (CQI) is an essential element of uplink control signaling in Long Term Evolution (LTE) system. According to 3GPP standard, a linear block code based on Reed-Muller (RM) code has been employed for the CQI transmission for error control. In this paper, a low complexity maximum a posteriori probability (MAP) decoding algorithm for CQI decoding is described, which is performed by re-ordering the likelihood values of the received signal and all mapped codewords, and then calculating the probability of 0 and 1 of every transmitted information bit based on a butterfly-flow-graph (BFG). Compared to the standard MAP decoding algorithm, the proposed algorithm can reduce the addition calculation by 35.71% to 72.82% when the number of CQI bit is changing from 4 to 11, and the bit error rate (BER) performance is without degradation.


3GPP-LTE CQI MAP decoding 


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Copyright information

© ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 2018

Authors and Affiliations

  • Qi Li
    • 1
  • He Wang
    • 1
  • Yunchuan Yang
    • 1
  • Bin Yu
    • 1
  • Chengjun Sun
    • 1
  1. 1.Samsung Research Institute China - Beijing (SRC-B)BeijingChina

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