Title :
Soft-in/soft-out Hadamard despreader for iterative decoding in the IS-95(A) system
Author :
Herzog, Rupert ; Hagenauer, Joachim ; Schmidbauer, A.
Author_Institution :
Dept. of Commun. Eng., Tech. Univ. of Munich, Germany
Abstract :
In the uplink of the CDMA IS-95(A) system decoding of a serial concatenated coding scheme has to be performed, where the inner code comprises M-ary orthogonal modulation with Hadamard (Walsh) spreading codes. For a coherent and a noncoherent RAKE-receiver structure we give the optimum symbol-by-symbol maximum a posteriori (MAP) decoding rules considering the a priori information about the systematic bits of the codewords if available. These algorithms are necessary for iterative decoding of the whole system. We present simulation results which demonstrate the gain of the modified receivers
Keywords :
Gaussian channels; cellular radio; code division multiple access; concatenated codes; forward error correction; interleaved codes; iterative methods; land mobile radio; maximum likelihood decoding; modulation coding; pseudonoise codes; radio links; radio receivers; spread spectrum communication; AWGN channels; DS-CDMA; Hadamard spreading codes; IS-95(A) system; M-ary orthogonal modulation; Walsh spreading codes; a priori information; algorithms; codewords; coherent RAKE-receiver structure; forward error correction; gain; inner code; iterative decoding; maximum a posteriori decoding rules; modified receivers; noncoherent RAKE-receiver structure; serial concatenated coding; simulation results; soft-in/soft-out Hadamard despreader; systematic bits; uplink; Delay; Error correction; Error correction codes; Iterative decoding; Maximum likelihood decoding; Maximum likelihood detection; Modulation coding; Multiaccess communication; RAKE receivers; Viterbi algorithm;
Conference_Titel :
Vehicular Technology Conference, 1997, IEEE 47th
Conference_Location :
Phoenix, AZ
Print_ISBN :
0-7803-3659-3
DOI :
10.1109/VETEC.1997.600525
