Title :
Real-time algorithms and VLSI architectures for soft output MAP convolutional decoding
Author :
Dawid, Herbert ; Meyr, Heinrich
Author_Institution :
Tech. Hochschule Aachen, Germany
Abstract :
Soft output decoding algorithms have been attracting considerable attention for concatenated or iterative decoding systems. The most prominent is the soft output Viterbi algorithm (SOVA), which can be regarded as an approximation to the optimum symbol by symbol detector, the symbol by symbol MAP algorithm. The MAP algorithm is a block detector, i.e. it requires completed reception of a terminated block of received symbols, which prevents an efficient real-time implementation. Therefore, up to now, the SOVA was considered to be the more attractive alternative. In this paper, we first introduce an algebraic formulation for the MAP. Using this formulation, a novel real-time MAP algorithm (SMAP) is derived, and it is proved that in terms of hard decoding performance, the SMAP is equivalent to the VA with path memory truncation and best state decoding. The finally presented SMAP architectures provide a competitive alternative to the known SOVA architectures for soft output decoding applications
Keywords :
VLSI; Viterbi decoding; computational complexity; convolutional codes; digital signal processing chips; maximum likelihood estimation; real-time systems; receivers; SMAP; SOVA; VLSI architectures; algebraic formulation; best state decoding; concatenated decoding; iterative decoding; optimum symbol by symbol detector; path memory truncation; real-time algorithms; received symbols; soft output MAP convolutional decoding; soft output Viterbi algorithm; symbol by symbol MAP algorithm; terminated block; Concatenated codes; Convolution; Convolutional codes; Delay; Detectors; Iterative algorithms; Iterative decoding; Signal processing algorithms; Very large scale integration; Viterbi algorithm;
Conference_Titel :
Personal, Indoor and Mobile Radio Communications, 1995. PIMRC'95. Wireless: Merging onto the Information Superhighway., Sixth IEEE International Symposium on
Conference_Location :
Toronto, Ont.
Print_ISBN :
0-7803-3002-1
DOI :
10.1109/PIMRC.1995.476882