The Research On The Distributed Beamforming Scheme In Multicell Cooperative System

In cellular systems, providing coverage and supporting a large number of userswith limited spectrum available is a challenge. Especially, in order to improve theperformance of cell edge users, the cooperative technology of multi-cell, multi-userand multi-antenna is research focus at home and abroad. Coordinated Multi-Pointtransmission (CoMP) technology has been introduced into the LTE-A system.Through collaboration and sharing the channel data between the adjacent base stations,CoMP can effectively improve the performance of the cell edge users. However, thecomplete sharing of the channel data between base stations will cause some delay, andthe feedback overhead is a big burden for the system.To solve the above problems, this thesis focuses on the research on the distributedbeamforming scheme in multi-cell cooperative system, as follows:Firstly, this paper proposes a distributed iterative scheme on joint beamformingand power allocation. Using the up-downlink duality of TDD system, thebeamforming vector and the power allocation can be decoupled. In the pre-set SNRthreshold, through the distributed iterative computing between the beamformingvector and power allocation, the suboptimal solution can be achieved.Secondly, a distributed precoding matrix design and power allocation algorithm isproposed. Through the joint optimization of the precoding vector and the powerallocation factor, the interference from other cells can be restrained, which avoids tobuild the complex central control node, achieves to maximize the signal to noise andleakage ratio, and is simple to implement. The simulation results show that, theperformance of the proposed algorithm is superior to the existing precoding designalgorithms.