The Research Of Multi-cell Cooperative Communication And Interference Coordination In Downlink System

As the spectrum resource is becoming more and more scarce, full frequency reusetechnology has attracted unprecedented attention with its spectrum efficiency advantage.How to reduce or even eliminate the interference between cells while enhancing thespectrum frequency reuse efficiency at the same time is quite necessary. Cooperativecommunication, one of the important technical means, is considered to be “the last goldenhill” in the future of wireless communication.The paper will research collaboration communication of multiple base stations,focusing on the user’s signal transmission problem in the cell-edge overlapping coveragearea. On the basis of the original cooperation means, where two cooperative base stationstransmit the same signal simple and acquire transmit diversity gain, we proposes acollaborative code transmit diversity technique, namely the two cooperative base stationstransmitting different redundancy codes of the same source information. At the same time,the cooperative base stations jointly design precoding matrix to ensure that the receivercan correctly decode. Compared with the prior simple transmit diversity gain, theproposed collaborative code transmit diversity technique, can introduce the redundantcoding gain without reducing the space diversity gain, and with no additional overhead.We expect to significantly improve the transmission performance.On the other hand, as for the huge interactive information and large iterativecomputation complexity of the K point-to-point single antenna interference alignmentalgorithm, this paper introduce a kind of distributed interference coordination method withmulti-antenna users, where we consider the coexisting interference of intra-cell andinter-cell users. Through weak or no collaboration between base stations, the interferencecoordination not only eliminates the iterative calculation complexity, but also withoutinteracting large information between base stations. Besides, as for the incompleteness ofeliminating interference caused by random user selection, where the channel correlationbetween users is too large and makes the angle between beam-forming vectors byzero-forcing beam-forming algorithm is too small, this paper presents a interferencealignment algorithm based on semi-orthogonal user selection. Further, we from the perspective of receiving point, enhance the semi-orthogonal user selection by using thereceiving channel parameters, which is expected to eliminate interference more efficiently,and will further reduce the computation complexity.Finally, through the simulation results, we prove that the coded cooperation, with theintroduction of different redundancy versions of information transmission scheme, canacquire additional coding gain in the high SNR, and the bit error rate and the block errorrate are improved. Also through the simulation, we prove that the interference alignmentbased on semi-orthogonal user selection by effective channel parameters scheme, theelimination of the interference among users is more thoroughly, and the computationcomplexity is greatly reduced because of the reduced dimension of channel matrix.