Low complexity cooperative downlink beamforming in multiuser multicell networks

In a network with frequency reuse-1, especially cell edge users are subject to strong intercell interference. This paper presents a low complexity downlink beamforming technique with multipoint transmission to a scheduled user to improve its signal to noise plus interference ratio. The dual problem for the max-min beamforming problem with a per base station (BS) power constraint and multi-BS assignment is derived and a low complexity algorithm based on the simple power iteration method for the generalized eigenvector decomposition is presented. Especially cell edge users gain from the presented technique and, therefore, an improved sum rate can be achieved, because of the max-min approach. The presented algorithm has a very low complexity and a fast convergence and is, therefore, promising for practical approaches for fast beam switching combined with optimized scheduling based on multiple base station assignment.