Abstract

We study quantization of log-likelihood ratios (LLR) in bit- interleaved coded modulation (BICM) systems in terms of an equivalent discrete channel. We derive the optimal quantizer for this problem, which is difficult to implement in practice, and therefore we propose an easily implementable quantizer design. We investigate semi-analytically and numerically the ergodic and outage capacity over single- and multiple-antenna channels of the proposed quantizer and compare it with the optimal quantizer. Finally, we show bit error rate simulations for BICM systems with LLR quantization using low-density parity-check codes.

BIO : Clemens Novak was born in Vienna, Austria, in 1980. In 2005 he received the Dipl.-Ing. degree in Electrical Engineering from Vienna University of Technology. Currently, he is a Research and Teaching Assistant with the Institute of Communications and Radio Frequency Engineering, Vienna University of Technology, and works towards his Ph.D. degree. His research interests are receiver algorithms for multi-user MIMO systems, especially IDMA systems, algorithm design using graphical models, and information theory.