Performance Analysis and Interleaver Structure Optimization for Short-Frame BICM–OFDM Systems

摘要

Bit-interleaved coded modulation (BICM), together with orthogonal frequency-division multiplexing (OFDM) signaling, has found its application in many recent wireless standards. BICM–OFDM systems are able to simplify the design of coding and modulation with various information rates for link adaptation. Furthermore, they provide robustness against frequency-selective fading channels. The combination of BICM–OFDM and convolutional code turns out to be attractive as it allows for low complexity and low latency decoding architecture at the receiver. It has been known that the performance of convolutionally coded BICM–OFDM systems depends on the bit interleaver structure, but little attention has been paid for its theoretical performance analysis. In this paper, we develop a novel theoretical expression for approximate BER of convolutionally coded BICM–OFDM that can be used for evaluating the performance of a given bit interleaver structure, and propose a design guideline for its optimization. Numerical comparisons between the optimized interleaver that satisfies our guideline and other random and structured interleavers demonstrate the validity of our design criterion.