关键词: 码分多址, 多用户检测, 递归最小二乘, 子空间跟踪, 信源估计

Abstract:

To overcome the issue that the performance of the subspace-based blind multiuser detector degrades due to underestimation of the sources' number in direct sequence/code division multiple access (DS/CDMA) systems, a novel subspace tracking strategy is presented and the recursive least square (RLS) blind multiuser detection algorithm is modified. As for the novel subspace tracking strategy, the desired user's signature waveform constitutes one part of the signal subspace and its orthogonal complement is tracked as the other parts of that signal. This brings the benefits of a small signal subspace estimation error and lower computational complexity. Even in the underestimation of the sources' number, the performance of the detector does not degrade significantly because the signal subspace always maintains the information on the desired user. The RLS blind multiuser detection algorithm is combined with the subspace approach. As a result of forward error feedback, this algorithm can reduce sensitivity to signal subspace estimation. Simulations are provided to demonstrate the effectiveness of the proposed detector.

Key words: code division multiple access (CDMA), multiuser detection, recursive least square (RLS), subspace tracking, source enumeration