System outage probability analysis of distributed antenna systems with beamforming

Distributed antenna systems (DAS) have been studied in cellular communication systems to improve system performance and enhance system capacity. This paper studies the system outage performance of downlink DAS with beamforming at antennas ports (AP). Firstly, a composite channel including Rayleigh fading, shadowing and path loss is established. Then, the mathematical expression of system outage probability is derived and further the interference among APs is considered. The system outage probability is computed via mathematical approximate methods. Numerical results show that the mathematical expression of system outage probability is precise and is in accordance with Monte Carlo simulation. In addition, different MS distribution and interference among APs both produce an effect on system outage probability.