说明：  多输人多输出(MIMO)技术是第三代和未来移动通信与个人通信系统实现高数据速率，提高传输质量 的重要途径[1 ]。目前MIMO系统中使用的发射方案主要包括：①贝尔分层空时结构BI STA(Bell Layered Space Time Architecture)[。 ；②正交空时分组码OSTBC(Orthogonal Space Time Block Coding) ；⑧空时 格型编码STTC(Space Time Trellis Coding) 。
(Motivated by the need for high throughput sphere decoding formultipleinput- multiple-output (MIMO) communication systems, we propose a parallel depth-first sphere decoding (PDSD) algorithm that provides the advantages of both parallel processing and rapid search space reduction. The PDSD algorithm is designed for efficient implementation on programmable multi-processor platforms. We investigate the trade-off between the throughput and computation overhead when the number of processing elements is 2, 4 and 8, for a 4× 4 16-QAM system across a wide range of SNR conditions. Through simulation, we show that PDSD can offer significant throughput improvement without incurring substantial computation overhead by selecting the appropriate number of processing elements according to specific SNR conditions.)