Distributed spatial division multiple access technique for spectrum sharing systems

Fourth generation (4G) systems will support co-deployment with other wireless networks based on different radio access technologies (RAT). To enable this coexistence and improve spectrum utilization efficiency, many mechanisms will be proposed. In this paper, we propose a distributed spatial division multiple access (SDMA) technique to prevent mutual interference among coexisting peer systems in areas of overlap. The SDMA technique is performed distributively after securing the cooperation of the coexisting base stations. With the implementation of the proposed distributed SDMA technique, the coexisting systems can use the same time-frequency resources to provide wireless services without generating harmful mutual interference. From the simulation results, we demonstrate that the proposed distributed SDMA improves bandwidth efficiency up to three times over the existing method.