A 0.58-mm2 2.76-Gb/s 79.8-pJ/b 256-QAM Message-Passing Detector for a 128 × 32 Massive MIMO Uplink System

Massive multiple-input–multiple-output (MIMO) detection uses a large number of antennas to increase spectral efficiency at a cost of large computation resources and power in a base station. In this article, we demonstrate a 0.58-mm2 $128\times 32$ (it denotes 128 base station antennas and 32 single-antenna users) 256-QAM massive MIMO uplink detector based on message-passing detection (MPD). With the proposed symbol hardening processing, the complexity is reduced by more than 60% compared to the direct implementation of MPD. The detector implements a grouped layer-parallel architecture to accelerate convergence, enabling an average throughput of 2.76 Gb/s (running, on average, 4.92 iterations with early termination) at 221 mW. The chip incorporates adaptive precision control and clock gating to improve energy efficiency further by up to 43%.