Subspace-based detection for CDMA communications

The oblique projection supports the framework to resolve a signal space into desired signal and interference subspaces. This paper presents subspace-based detection methods using the oblique projection for the CDMA channel. For the synchronous case, it is shown that this detector represents the geometrical form of the decorrelating detector, and performs a complete rejection of interfering signals. This paper also suggests the approach of combining the subspace-based detection with the MUSIC algorithm for an asynchronous CDMA channel. It is shown that the BER performance of this detection approach, which depends on the accuracy of the code timing acquisition, is better than that of the blind adaptive demodulation technique.