Low-complexity relay precoder designs for two-way AF MIMO relay systems

• Published in: IEEE International Conference on Communications (2003) pp. 1 - 6
• Main Authors: Wang, Chin-Liang, Chen, Jyun-Yu, Peng, Yi-Hsuan
• Format: Conference Proceeding Journal Article
• Language: English
• Published: IEEE 01.05.2016
• Subjects: amplify-and-forward (AF); Channels; Complexity; condition number; Conferences; Decision support systems; Design engineering; MIMO; MIMO (control systems); multiple-input multiple-output (MIMO); Precoding; Relay; Relay systems; Searching; Signal processing; two-way relaying
• ISSN: 1938-1883
• DOI: 10.1109/ICC.2016.7511606

An eigenmode-selection approach was recently presented for relay precoding subject to the minimum/maximum sum of condition numbers of the effective multiple-input multiple-output (MIMO) channels in a two-way amplify-and-forward (AF) MIMO relay system. Although this method can achieve close-to-optimal performance, it would involve high search complexity for the solution in a relay precoding set of size 2·M!, where M is the degrees of freedom of the MIMO relay system. In this paper, we propose low-complexity relay precoder designs based on eigenmode selection for two-way AF MIMO relay systems. We first exploit the properties of condition numbers of the effective MIMO channels, and then present two set-reduction methods accordingly for eigenmode-selection precoding to minimize/maximize the sum of condition numbers. As compared with the original eigenmode-selection precoding scheme, the proposed designs reach similar performance but reduce the search complexity by a factor of M(M-1).