Beamforming for IEEE 802.11b using a joint conjugate gradient multistage wiener filter.

This paper presents a joint reduced rank adaptive beamforming technique using smart antennas that can be applied to systems using direct sequence spread spectrum (DSSS), and we analyze its performance using the IEEE 802.11b signaling standard. The algorithm is based on a joint implementation of the conjugate gradient (CG) multistage Wiener filter (MWF), called the CG-MWF. This algorithm is more robust in a multiuser environment than its single user and full rank counterparts, as well as more efficient to implement, in that it requires a very low rank to adapt the beamformer weights. Multiple signals are assumed, which produce a co-channel interference (CCI) scenario. We show that the algorithm provides up to 7 dB improvement over the single user CG-MWF when the power levels of the users are similar. We demonstrate the robustness of the algorithm under dynamic conditions, such as when the number of users, their powers, and their directions-of-arrival (DoAs) change or when a user is traveling at driving speeds.