Low Complexity Soft-Input Soft-Output Detector Based on Repeated Tree Search Strategy

In Multiple-Input Multiple-Output (MIMO) schemes, the high computational complexity of soft optimal detection algorithms can make these algorithms impractical for real systems, especially when the number of antennas and modulation orders increase. In this paper, we present a modification on Repeated Tree Search (RTS) strategy, reducing the complexity by using Box- Optimization (BO) method combined with the Zero Forcing (ZF) algorithm. The proposed soft input soft output algorithm presents lower complexity than already proposed optimal algorithms, however it loses the optimal behavior. The proposed suboptimal soft detector exhibits a scalable tradeoff between complexity and performance.