On adaptive LCMV beamforming for multiuser processing in wireless systems

Multiuser processing, using an antenna array, has emerged as a suitable solution for capacity increase in wireless systems. The use of an antenna array reduces the multiuser interference, allowing two or more users to share systems resources in an efficient way. The use of a Linearly Constrained Minimum Variance (LCMV) criterion to optimize the antenna array weights has been proved to be a good solution for multiuser processing. This work presents an unified view of LCMV beamforming, including a solution that avoids direction of arrival (DOA) estimation and is able to cope with angular spread. An adaptive versions of the resulting technique is also presented. Moreover, we evaluate the performance of the proposed techniques in non-zero angular spread and non-stationary environments. The results provide an overview of the potential of LCMV techniques in multiuser wireless communication systems.