Research on Hybrid-ARQ Chase Combining Algorithms in ZF-SIC V-BLAST

Abstract

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.

Novel HARQ schemes for MIMO single-hop and Multi-hop relay systems

“…Various improvements have been proposed for the MMARQ process in terms of detection ordering and combining criteria [5]- [8]. However, all these schemes consider postcombining for the HARQ process.…”

“…In [5] and [6], joint detection schemes have been proposed to improve the procedure of post-combining scheme, whereas [7] proposes an improvement in the detection ordering procedure of MMARQ. A bit-level post-combining scheme for Zero Forcing (ZF) V-BLAST based on log-likelihood ratio (LLR) is proposed in [8]. All the research in [4]- [8] focuses on using post-combining but the advantages of pre-combining have not been exploited.…”

“…A bit-level post-combining scheme for Zero Forcing (ZF) V-BLAST based on log-likelihood ratio (LLR) is proposed in [8]. All the research in [4]- [8] focuses on using post-combining but the advantages of pre-combining have not been exploited.…”