Joint-Beamforming Based Downlink Space Division Multiple Access

Space division multiple access (SDMA) technique in multiple antennas system canmultiply increase the system’s capacity to support more users with limited spectrum,improving the spectrum efficiency. Downlink SDMA is generally realized by arrayantenna techniques or Multiple-Input Multiple-Output (MIMO) techniques. Aiming atsome existing problems of downlink SDMA, this thesis makes contributions in:(1) To overcome the large interference problem in SDMA of array antenna systemand the problem performance degradation in SDMA of MIMO system in a correlatedfading channel, a joint beamforming based downlink SDMA scheme for single arraywhich combines array beamforming and MU-MIMO beamforming is proposed.(2) Based on (1), eigenbeamforming for multi-user is researched; eigenbeamformingconverts the fading channels into orthogonal ones, it can make better advantage ofMU-MIMO beamforming.(3) When the beams of the users’ are close to each other, the joint beamforming basedSDMA of single array has a performance degradation because of the relevance of thebeams, we proposed a multiple-array-antenna system for the joint beamforming basedSDMA, the arrays of the proposed system are independent in space, making the beamsof the arrays independent, so it can have a better performance than the single arraysystem when the users’ beams are close.