Title :
Gallager codes for CDMA applications: generalizations, constructions and performance
Author :
Sorokine, Vladislav ; Kschischang, Frank R. ; Pasupathy, Subbarayan
Author_Institution :
Dept. of Electr. & Comput. Eng., Toronto Univ., Ont., Canada
Abstract :
We focus on applications of low rate (low-density parity-check) Gallager (1963) codes in code-division multiple access (CDMA) schemes. These codes can be decoded with low complexity by using iterative decoding procedures. We present a construction that yields good, short frame length, low rate Gallager codes. We estimate that by using Gallager codes, a factor of five improvement in CDMA cell capacity relative to an uncoded system can be achieved, equivalent to a factor of two improvement relative to state-of-the art orthogonal convolutional codes. Simulation results show that, compared with short frame length turbo codes, Gallager codes achieve a 0.5 dB improvement in AWGN channels and over 2 dB improvement in fading channels in the signal-to-noise ratio required to achieve frame error rates of 10-3
Keywords :
AWGN channels; cellular radio; channel capacity; code division multiple access; computational complexity; error correction codes; error statistics; fading channels; iterative decoding; AWGN channels; CDMA applications; CDMA cell capacity; binary linear codes; cellular radio applications; code-division multiple access; error control codes; fading channels; frame error rates; iterative decoding; low complexity decoding; low rate Gallager codes; low-density parity-check; minimum Hamming distance; orthogonal convolutional codes; performance; short frame length turbo codes; signal-to-noise ratio; simulation results; uncoded system; AWGN channels; Art; Convolutional codes; Fading; Iterative decoding; Multiaccess communication; Parity check codes; Signal to noise ratio; State estimation; Turbo codes;
Conference_Titel :
Information Theory Workshop, 1998
Conference_Location :
Killarney
Print_ISBN :
0-7803-4408-1
DOI :
10.1109/ITW.1998.706373
