A Multi-Interference-Channel Matrix Pair Beamformer for CDMA Systems

Matrix pair beamformer (MPB) is a promising blind beamformer which exploits the temporal signature of the signal of interest (SOI) to acquire its spatial statistical information. It does not need any knowledge of directional information or training sequences. However, the major problem of the existing MPBs is that they have serious threshold effects and the thresholds will grow as the interference power increases or even approach infinity. In particular, this issue prevails in scenarios with structured interference, such as, periodically repeated white noise, tones, or MAIs in multipath channels. In this paper, we will first present the principles for designing the projection space of the MPB which are closely correlated with the ability of suppressing structured interference and system finite sample performance. Then a multiple-interference-channel based matrix pair beamformer (MIC-MPB) for CDMA systems is developed according to the principles. In order to adapt to dynamic channels, an adaptive algorithm for the beamformer is also proposed. Theoretical analysis and simulation results show that the proposed beamformer has a small and bounded threshold when the interference power increases. Performance comparisons of the MIC-MPB and the existing MPBs in various scenarios via a number of numerical examples are also presented. Index Terms This work was supported by the National Natural Science Foundation of China under Grant No. 60928001 and No. 60972019. Jian Wang, Jian Yuan and Ning Ge are with the Department of Electronic Engineering, Tsinghua University, Beijing, P. R. China, 100084. (e-mail: {jian-wang, jyuan, gening}@tsinghua.edu.cn) Jianshu Chen is with the Department of Electrical Engineering, University of California, Los Angeles, CA 90095-1594, USA. (e-mail: [email protected]) Shuangqing Wei is with the Department of Electrical and Computer Engineering, Louisiana State University, Baton Rouge, LA 70803, USA. (e-mail: [email protected]). His work was supported in part by Louisiana Board of Regents under Grant No. LEQSF(2009-11)-RD-B-03 and the National Science Foundation (NSF) of US under Grant No. CNS-1018273. October 4, 2010 DRAFT 2 Adaptive arrays, code division multiple access (CDMA), matrix pair beamformer, structured interference.