TRIP: Tree Search-Based Iterative Detection and Decoding for Polar-Coded MIMO Systems

With the rapid development of wireless communications, future applications call for an increase in reliability performance. Thanks to the soft information exchange between detection and decoding, iterative detection and decoding (IDD) exhibits superior performance over separate detection and decoding (SDD). In this letter, we introduce TRIP, a tree search-based IDD receiver designed for polar-coded multiple-input multiple-output (MIMO) systems. To enhance the error rate performance of TRIP and reduce its complexity, we utilize the $\mathscr {S}$ metric selection evolutionary multiobjective optimization algorithm (SMS-EMOA). This algorithm refines the extrinsic information and the layer width of detectors and decoders, achieving an improved balance between performance and complexity. Simulation results indicate that TRIP outperforms its SDD mode by 1.38 dB at a frame error rate (FER) of $10^{-3}$ , and gains an additional 0.68 dB by fine-tuning the extrinsic information. The complexity of the detector and the decoder is reduced by 56.3% and 37.8% without compromising their performance gains, respectively.