A Low Cost Multi-Standard Near-Optimal Soft-Output Sphere Decoder: Algorithm and Architecture
The authors present an algorithm and architecture of a soft-output sphere decoder with an optimized hardware implementation for 2x2 MIMO-OFDM receptions. They introduce a novel table look-up approach for symbol enumeration that simplifies the implementation of soft-output decoders. The HW implementation is targeted towards WLAN (IEEE 802.11n) with stringent latency and throughput requirements. The current implementation supports all modulation schemes (BPSK, QPSK, 16- QAM, and 64-QAM) and shows near-optimal real-time performance. To achieve this, the sphere decoder computes in the worst-case Euclidean distances of 4.1 Giga QAM symbols per second.