A Soft Iterative Receiver With Simplified EP Detection for Coded MIMO Systems

Expectation propagation (EP) achieves excellent performance with high-order modulation in massive multiple-input multiple-output (MIMO) detection. The soft output of the EP detector can be iteratively combined with turbo soft decoders to enhance error-correction performance. However, the implementation of EP-based iterative detection and decoding (IDD) receivers suffer from an exponential increase in computational complexity as the number of antennas and modulation order grows. In this brief, we propose a simplified EP approximation-based IDD (sEPA-IDD) scheme for hardware implementation. To alleviate the computational burden, a simplified message update scheme is proposed, reducing complexity by 68% without performance degradation. Additionally, a unified design for extrinsic message computation further improves hardware utilization. Finally, we introduce the first unfolded EP-based IDD architecture to boost throughput. Compared with state-of-the-art (SOA) IDD receivers, the sEPA-IDD receiver implemented on 65 nm CMOS delivers a throughput of 3.07 Gb/s with a maximum 0.5 dB gain, achieving $4.03\times $ higher throughput and $6.04\times $ greater area efficiency.