In the conventional zero-forcing successive interference cancellation (ZF-SIC) detection algorithm of vertical Bell-Labs layered space-time (V-BLAST) architecture, the detection algorithm does not attempt to eliminate the effect of the error propagation, which is significantly deleterious to hybrid automatic repeat request (H-ARQ) scheme using bit-level Chase combining. Based on two ordering approaches respectively, we propose two novel H-ARQ bit-level Chase combining algorithms in this paper, which employ a new log-likelihood ratio (LLR) calculation algorithm to minimize the effect of the error propagation. Additionally, we bring forward a new pairwise LLR combining technique to enhance the reliability of ordering stage considerably. Through simulation results, it is shown that the new proposed algorithms outperform the conventional ones in system performance.
There have been great efforts to study the adaptive MIMO systems, while all of them concentrate on the systems without channel coding. This paper presents a new adaptive V-BLAST scheme adopting turbo-codes as the channel coding. Through a two-step method, we derive two algorithms for fixed rate and variable rate applications respectively. We derive a closeform bit and power allocation algorithm which reduces the computation complexity greatly by avoiding exhaustive search. For adaptive coding, we propose the Average SNR mapping method to select the proper coding scheme. Simulation results show that the algorithms for fixed rate and variable rate both provide very good throughput performance with low complexity and less feedback information.
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