High-order-modulation large MIMO detector based on physics-inspired methods

Applying quantum annealing or current quantum- and physics-inspired algorithms for multiple-input multiple-output (MIMO) detection always abandon the direct Gray-coded bit-to-symbol mapping in order to obtain Ising form, leading to inconsistency errors. This often results in slow convergence rates and error floor, particularly with high-order-modulations. We propose HOPbit, an alternative MIMO detector designed to address this issue by transforming the MIMO detection problem into a higher-order Ising problem while maintaining Gray-coded bit-to-symbol mapping. The method then employs the simulated probabilistic bits (p-bits) algorithm to directly solve higher-order Ising problem without degradation. This innovative strategy enables HOPbit to achieve rapid convergence and attain near-optimal maximum-likelihood performance in most scenarios, even those involving high-order-modulations. The experiments show that HOPbit surpasses ParaMax by several orders of magnitude in terms of bit error rate (BER) in the context of 12-user massive and large MIMO systems even with less computing resources. In addition, HOPbit achieves lower BER rates compared to other traditional detectors.