Box Decoding is a sort-free tree-search MIMO detector whose complexity is independent of the QAM order, achieved by searching a fixed candidate box around a zero-forcing (ZF) estimate. However, without pruning, the number of visited nodes grows exponentially with the MIMO dimension, limiting scalability. This work proposes two deterministic, low-complexity, sort-free pruning strategies to control node growth. By exploiting the geometric symmetry of the QAM grid and the relative displacement between the ZF estimate and nearby constellation points, the proposed methods eliminate unnecessary metric evaluations while preserving QAM-order independence. The resulting detector achieves substantial complexity reduction with negligible error-rate degradation and enables fully parallel, hardware-efficient implementations for large-scale MIMO and higher-order QAM systems.

翻译：盒解码是一种无排序树搜索MIMO检测器，其复杂度与QAM阶数无关，这是通过在迫零估计周围搜索固定候选盒实现的。然而，若不进行剪枝，访问节点数会随MIMO维度呈指数增长，限制了可扩展性。本文提出了两种确定性、低复杂度、无排序的剪枝策略来控制节点增长。通过利用QAM网格的几何对称性以及迫零估计与邻近星座点之间的相对位移，所提方法在保持QAM阶数独立性的同时消除了不必要的度量评估。最终实现的检测器在误码率性能几乎无损的情况下显著降低了复杂度，并为大规模MIMO和高阶QAM系统实现了完全并行、硬件高效的实现方案。