Gbps Soft-Output K-Best MIMO Detector Design with Relaxed Parallel Sorting

Multiple-input multiple-output (MIMO) technique can significantly increase data throughput without sacrificing additional bandwidth. This paper proposes a soft-output K-Best detector for 4 × 4 64-QAM MIMO system to achieve Gbps throughput. The key contribution of this work is proposing the relaxed 2-parallelism sorting scheme which can produce two survivor paths simultaneously, thus significantly improve the throughput. Furthermore, utilization of upper levels´ discarded paths (DPs) and direct zero forcing (ZF)-augmentation to survivor paths in last two stages are adopted to obtain good BER performance with low complexity. This proposed detector outperforms the conventional soft-output K-Best scheme by 3.5dB at BER=10-4 when using the minimum mean squared error-sorted QR decomposition (MMSE-SQRD) channel preprocessing. Fabricated in SMIC 0.13 μm CMOS, the VLSI implementation achieves a peak throughput of 1.368 Gbps and consumes 84 cycles for latency.