Subband CMA adaptive arrays in multipath fading environment

Abstract

SUMMARY CMA (Constant Modulus Algorithm) adaptive arraysare considered a promising method in mobile communica-tions to mitigate multipath fading and to suppress co-chan-nel interference signals. However, since a CMA adaptivearray assumes no a priori information of the desired signal,it is difficult to separate and combine the multipath rays ofthe desired signal. Therefore, when CMA is applied, theinput signal power of the multipath rays cannot be effi-ciently utilized. Moreover, since suppressing the multipathrays requires many degrees of freedom (DOFs) of the array,the array system becomes complicated. In this paper we propose the subband CMA adaptivearray which enhances the signal correlation between themultipath rays in each subband, as such the multipathfading effect can be greatly mitigated. By using thismethod, the multipath rays of the desired signal are equal-ized and combined, whereas an interference signal withmultipath rays can be suppressed by using a single DOF.' 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(11):43Œ54, 2000Key words: CMA adaptive array; multipath fading;co-channel interference; filter banks; blind signal process-ing.