A 0.58mm2 2.76Gb/s 79.8pJ/b 256-QAM massive MIMO message-passing detector

A 0.58mm2 40nm CMOS message-passing detector (MPD) is designed for a 256-QAM massive MIMO system supporting 32 concurrent mobile users in each time-frequency resource. Leveraging channel hardening in massive MIMO, a symbol hardening technique is proposed to reduce MPD's complexity by more than 60% with minimal SNR loss. The MPD is implemented in a 4-layer 2-way interleaved architecture to enable a 2.76Gb/s throughput (average 4.9 iterations at 27dB SNR with early termination) using 76% smaller area than a fully parallel architecture. With dynamic precision control and clock gating to exploit algorithmic properties, the energy is reduced to 79.8pJ/b (or 2.49pJ/b per TX antenna).