Title :
An adaptive coded modulation scheme associated with improved HARQ
Author :
Chen, Hong ; Pingzhi Fan
Author_Institution :
Inst. of Mobile Commun., Southwest Jiaotong Univ., Chengdu, China
Abstract :
In this paper, an adaptive coded modulation scheme associated with improved HARQ is proposed. In the scheme, non-uniform constellation Gray encoding for the modulation with alphabet size M>4 is adopted in the retransmissions. Combining with the symbol bits rearrangement before modulation mapping and non-uniform constellation for retransmission in HARQ scheme, the reliability of each bit inputting to the turbo decoder is averaged and improved. As a result, the system throughput is increased effectively, and it is noticed that the throughput of 1/2 code rate 8PSK with the improved HARQ is shown to be better than 3/4 code rate QPSK with conventional HARQ. So instead of 3/4 code rate QPSK, a novel adaptive coded modulation scheme associated with improved HARQ is proposed, and the system throughput gets a significant performance improvement.
Keywords :
Gray codes; adaptive codes; adaptive modulation; automatic repeat request; decoding; modulation coding; quadrature phase shift keying; turbo codes; 8PSK; HARQ scheme; QPSK; adaptive coded modulation; nonuniform constellation Gray encoding; system throughput; turbo decoder; Automatic repeat request; Bit error rate; Constellation diagram; Decoding; Delay effects; Interference; Mobile communication; Modulation coding; Quadrature phase shift keying; Throughput;
Conference_Titel :
Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003. 14th IEEE Proceedings on
Print_ISBN :
0-7803-7822-9
DOI :
10.1109/PIMRC.2003.1260321
