Performance Assessment of MIMO-BICM Demodulators Based on Mutual Information

Abstract

In this paper we provide a comprehensive performance assessment and comparison of various soft-output and hard-output demodulation schemes for multiple-input multiple-output (MIMO) bit-interleaved coded modulation (BICM). Even though widely used in literature for demodulator comparison, coded bit error rate (BER) has the drawback of being strongly dependent on the outer error correcting code. This motivates us to propose a code-independent performance measure in terms of system capacity, i.e., mutual information of the equivalent modulation channel that comprises modulator, wireless channel, and demodulator. We present extensive numerical results for ergodic and quasi-static channels as well as for the case of imperfect channel state information. These results reveal that the performance ranking of MIMO demodulators is rate-dependent. Furthermore, they provide new insights regarding MIMO-BICM system design, specifically the joint selection of demodulation scheme, antenna configuration, and symbol constellation for a prescribed target rate.