VLSI architecture of the soft-output sphere decoder for MIMO systems

Sphere decoders can approach the performance of maximum-likelihood (ML) decoders for MIMO systems with lower complexity. In this paper, VLSI architecture of the modified K-best Schnorr-Euchner (MKSE) sphere decoder is proposed for soft-output MIMO decoding. The MKSE decoder can achieve near-ML performance with higher decoding throughput and lower computational complexity. The proposed VLSI architecture is implemented for a 4 × 4 16-QAM MIMO system in a 0.13-μm CMOS technology. The implemented soft-output MKSE chip can achieve a decoding throughput of more than 100 Mb/s with a 0.56 mm² core area and 97 K gates.