Study of SDM Downlink in Radio Access Network with Dynamic Adjustment of Antenna Direction

Spatial Division Multiplexing (SDM) technology exploits information transmission in spatial dimension in addition to temporal dimension to improve frequency utilization and enlarge transmission capacity. Dynamic adjustment of antenna direction according to the position of targeted user station can better release the potential of SDM. In this paper, we set up a software platform to study the performance of SDM downlink in Radio Access Network (RAN) with dynamic adjustment of antenna direction. Architecture of RAN with TDM/SDM downlink is first introduced to show their difference in slot allocation and transmission capacity. Independent and identically distributed Poisson process is used to simulate the traffic source of downlink. Throughput, packet loss rate and user data rate are calculated for scenarios with TDM and 1 to 4 SDM downlink carriers. Simulation results and analysis indicate that capacity of SDM downlink is of near linear relationship with the number of antennas and transmitters used in central station. Performance of RAN is prospected to be improved enormously by application of SDM technology.