【作者】 熊聪；

【导师】 张欣；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2010， 硕士

【摘要】 贝尔实验室垂直分层空时结构(V-BLAST)是一种追求复用的多天线系统,它能实现很可观的传输速率。因此,它是未来宽带通信系统的重要备选技术。V-BLAST系统的整体性能和接收机检测算法密切相关。众所周知,最大似然检测是最优的检测算法。然后,它的复杂度随着发送天线的数目增加而指数增长,这妨碍了它在实际系统中的使用。因此,我们很有必要找到低复杂度的近似最优接收机检测算法。本论文中主要介绍了三类近似最优算法及其改进算法：并行检测算法(PD),固定复杂度的球译码算法(SD)，以及自适应选择幸存路径算法(ASESS)。目前的并行检测算法有一个通病-它们把部分最大似然检测得到的所有路径等同处理,直到最终的欧氏距离判决。在并行检测算法部分,基于广义并行删除检测算法(GPIC),我们提出了两种简化算法。它们能够提前终止表现很差的路径,也只用后干扰删除处理那些概率较高的错误图样。之后,我们又提出了一种新的部分判决反馈的并行检测算法。计算机仿真表明三种新算法都能在性能和复杂度之间很好的折中。在固定复杂度的球译码部分,我们引入逐层剪枝的思想,提出了一种简化的固定复杂度的球译码算法。计算及仿真表明在8发8收,16QAM调制的V-BLAST系统中,简化算法的复杂度只有原算法的37%，并且几乎没有性能损失。在自适应选择幸存路径算法部分,我们提出了一种改进算法。它能在只增加很少复杂度的情况下,是检测性能大幅提升。它的优越性是因为它总能找到最优的M条路径,而原算法只能找到较好的M条路径。更多还原

【Abstract】 Vertical Bell Laboratories layered space-time (V-BLAST) architecture is a promising multiple-input multiple-output (MIMO) system, which mainly focuses on multiplexing and can provide high speed data rate. Thus, it is an important technique in future broadband wireless communication system.The overall performance of V-BLAST system is crucially related to the detection algorithm at the receiver. As is well known, the maximum likelihood detection (MLD) yields the optimal detection performance. However, it suffers from an exponential complexity with the number of transmit antennas, making it infeasible for high-dimensional V-BLAST systems. Therefore, it is of great significance to develop low-complexity detection algorithms for near-optimal detection for V-BLAST system.This thesis mainly deals with three types of near-optimal detection algorithms: parallel detection (PD), fixed-complexity sphere decoder (FSD) and adaptive selection of surviving symbol replica candidates (ASESS) algorithm.Nevertheless, the existing PD algorithms have a common drawback in equally handling all the branches obtained via partial MLD (PMLD) till reaching the final minimum Euclidean distance (MED) decision. In the PD part, two simplified algorithms are developed from a recently proposed generalized parallel interference cancellation (GPIC) algorithm, by means of early termination of the inferior parallel branches and only dealing with error patterns with high probability. Then, another novel PD with partial decision feedback is developed. Simulation results demonstrate that all the three novel algorithms can approach the near-optimal performance with low complexity.In the FSD part, a simplified fixed-complexity sphere decoder (SFSD) with much lower computational cost than that of the original FSD is developed for signal detection in V-BLAST system, by pruning the inverted tree layer by layer. Simulation results on a 16-QAM system with 8 transmit and 8 receive antennas show that the SFSD can attain the near-optimal performance with a cost that is about 37% of the counterpart of the original FSD.In the ASESS part, an improved ASESS detector achieving much performance gain compared with the original ASESS detector at the cost of almost the same computational complexity is investigated. The superiority of the improved ASESS algorithm over the original one is because it always finds out the M optimum paths while the original one can pick out merely M fine paths at each level.更多还原