Performance Validation for MMSE Turbo Equalization in ST-BICM Systems

Abstract

This paper presents a simple approach to assess performance that can be achieved by the MMSE turbo equalizer in ST-BICM systems over multipaths Rayleigh block fading channels with i.i.d fading statistics. By considering perfect information exchange between the SISO decoder and the linear MMSE equalizer, the performance reaches the matched filter bound, and a closed form expression of the corresponding probability of bit error can be derived at the output of the equalizer. In particular, we emphasize that the suggested approach provides an attractive and reliable tool for performance validation consistently with the proposed expression of the probability of bit error. Simulations for 4-PSK and 8-PSK modulated signals show the relevance of the proposed approach and the full benefit provided by the MMSE turbo equalizer. In addition some clarification of the signal-tonoise ratio definition is pointed out.Index Terms-Space-Time BICM, MMSE Turbo equalization, performance validation, Rayleigh block fading multipath channel, probability of bit error expression.

Efficient Frequency-Domain MMSE Turbo Equalization Derivation and Performance Comparison with the Time-Domain Counterpart

“…The proposed turbo equalizer differs from previous approaches in that feedforward and feedback filters are directly derived in the frequency domain. Asymptotic performance has been shown to be consistent with the probability of bit error derived in [11]. Simulations over multipath Rayleigh block fading channels show the structure equivalence in comparison with the time-domain approach.…”

“…III.E) is plotted as a reference (genie-equalizer and genie-decoder). The genieequalizer performance is compared to the corresponding analytical probability of bit error developed in [11]. We observe that both curves are indistinguishable which confirm the accuracy of the proposed FD algorithm.…”

“…The so-called genie FD MMSE turbo equalizer supresses multi-antenna interference and intersymbol interference for each transmit antenna, from the received signal. Assuming soft demapping without a priori knowledge, we can accurately predict asymptotic performance at the frequencydomain equalizer output following the proposed approach in [11]. Simulations are shown in section IV to confirm the purpose.…”

“…Considering the expression of R(p) and equations (10)(11)(12)(13)(14), one can easily obtain an equivalent expression of the equalizer output :…”