Lattice Reduction Aided Vector Precoding Techniques Usinga Candidate List for MIMO Communications Systems

• Main Authors: Yun-Shiuan Cheng, 鄭雲軒
• Other Authors: Chiao-En Chen
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/27040039209976752775

碩士 === 國立中正大學 === 通訊工程研究所 === 100 === Vector perturbation (VP) precoding, the precoding technique which perturbs the signal by some perturbation vector before transmission, can effectively improve the performance of a communications system. When combined with the use of multiple-input-multipleoutput (MIMO) technique, VP has been shown to achieve the full diversity gain. In this thesis, we propose several practical approaches to improve this technique. In the first part of the thesis, we introduce the lattice reduction (LR) algorithm to the recently proposed VP transceiver design with iterative power loading. Unlike the original algorithm which uses a sphere-decoder to search for the optimal perturbation vector, we propose to solve it via a number of LR-aided precoding schemes. Simulation results show that the proposed algorithms can significantly reduce the computational complexity at the expense of only marginal performance loss. In the second part of the thesis, we investigate ways of improving the vector perturbation techniques by using a candidate list. Two kinds of algorithms have been proposed. The first kind is based on the forward and backward LLL, which has been shown to provide improved error rate performance. The second kind reduces the computational complexity by exploiting the structure of the unimodular transformation matrix. The algorithms have been evaluated and compared via extensive computer simulations.