Title :
Exact and approximated expressions of the log-likelihood ratio for 16-QAM signals
Author :
Allpress, Steve ; Luschi, Carlo ; Felix, Steve
Author_Institution :
Icera Inc., Bristol, UK
Abstract :
This paper discusses the exact and approximate calculation of the bit log-likelihood ratio (LLR) for a 16-QAM signal. In particular, we introduce a new modified max function, which allows for an effective implementation of the LLR formula. The results of the paper are applicable to 16-QAM soft-demapping in digital receivers that perform soft decision decoding or iterative decoding.
Keywords :
iterative decoding; quadrature amplitude modulation; radio receivers; 16-QAM signal; LLR; bit log-likelihood ratio; digital receivers; iterative decoding; modified max function; quadrature amplitude modulation; soft decision decoding; soft-demapping; Availability; Code standards; Error correction codes; Iterative algorithms; Iterative decoding; Modulation coding; Multiaccess communication; Nonlinear filters; Signal processing; Turbo codes;
Conference_Titel :
Signals, Systems and Computers, 2004. Conference Record of the Thirty-Eighth Asilomar Conference on
Print_ISBN :
0-7803-8622-1
DOI :
10.1109/ACSSC.2004.1399245
