Decoupled direction finding: detection

Antenna arrays are likely to be an important feature of future mobile communication systems. With an antenna array, mobile users can be separated by a spatial filtering procedure allowing several users on the same carrier frequency. The uplink part (mobile to base) not only can, but is better solved without using any spatial knowledge in terms of direction of arrival (DOA). However, DOA estimation remains an important issue in the overall system, both for downlink beamforming, as well as channel allocation. Previous results have shown that DOA estimation is best performed in a post-detection manner, i.e., using the estimated symbol sequence for DOA estimation. In this way, the estimation problem can be decoupled to treat individual users separately. To estimate the number of propagation paths from a specific user, a detection scheme is derived based on the DOA estimation criterion function