In this paper, we propose an efficient soft-output signal detection method for spatially multiplexed multiple-input multiple-output (MIMO) systems. The proposed method is based on the ordered successive interference cancellation (OSIC) algorithm, but it significantly improves the performance of the original OSIC algorithm by solving the error propagation problem. The proposed method combines this enhanced OSIC algorithm with a multiple-channel-ordering technique in a very efficient way. As a result, the log likelihood ratio values can be computed by using a very small set of candidate symbol vectors. The proposed method has been synthesized with a 0.13-μm CMOS technology for a 4×4 16-QAM MIMO system. The simulation and implementation results show that the proposed detector provides a very good solution in terms of performance and hardware complexity.
Keywords: MIMO, OSIC, K-best, QRD-M, QRM-MLD.Manuscript received Oct. 1, 2010; revised Mar. 9, 2011; accepted Mar. 23, 2011. Tae Ho Im (phone: +82 10 2971 4008, email: taeho.im@gmail.com), Insoo Park (email: rhyle@naver.com), Hyun Jong Yoo (email: hyunjong.yoo84@gmail.com), Sungwook Yu (email: sungwook@cau.ac.kr), and Yong Soo Cho (corresponding author, email: yscho@cau.ac.kr) are with the School of Electrical and Electronic Engineering, Chung-Ang University, Seoul, Rep. of Korea.http://dx.doi.org/10.4218/etrij.11.0110.0574
I. IntroductionMultiple-input multiple-output (MIMO) communication systems have received tremendous attention because of their high spectral efficiency and near-capacity performance. As a result, MIMO has become a key component in several wireless communication standards, including LTE-Advanced and IEEE 802.16m [1].Multiple antennas can be used to improve the reception reliability by sending the same data (spatial diversity) or to increase data rates by sending different data (spatial multiplexing) [1], [2]. There are several detection methods for spatially multiplexed MIMO systems. The maximum likelihood (ML) algorithm leads to the best error performance, but it involves considerable computational complexity [1]. On the other hand, linear detection methods such as the zeroforcing algorithm or minimum mean-square-error algorithm are quite simple, but they show very poor performance. The ordered successive interference cancellation (OSIC) algorithm reduces the effect of interference signals by eliminating signals that are already detected [2]. Although the OSIC algorithm performs better than linear detection methods, it suffers from the error propagation problem [1], [2].As a result, most recent works have focused on the detection methods that are based on tree searches, which achieve nearoptimal performance but involve significantly less complexity than the original ML method [17]. These methods, however, cannot provide the best solution for soft-decoding MIMO systems because of the empty set problem [12], [13]. The proposed method enhances the OSIC algorithm and combines the algorithm with a multiple-channelordering technique in a very efficien...