Antenna beamwidth effects on capacity of MIMO and multi-beam phased array systems

The multiple input multiple output (MIMO) systems have been the center of interest for their potential in capacity increase over single input single output (SISO) systems. Authors introduced a new approach to realize maximum achievable capacity through pattern diversity by using multi-beam phased array (PA) antennas. Results showed more than 90% of the theoretical capacity limit could be achieved even when line of sight (LOS) exists. In previous studies, omni-directional antenna elements were used. Having a directional antenna provides better spatial channel selection. In current study, the effects of beamwidth for different array configurations on both MIMO and multi-beam phased array systems capacities are investigated. Preliminary results show smaller beamwidths can provide better capacity in multi-beam phased array system, while beam selection might be more difficult than when omni-directional elements are used. A ray-tracing method was used to simulate the system performance in a realistic propagation environment