Simulations of channel capacity and frequency reuse in multipoint LMDS systems

The results of several studies of microwave LMDS system capacity are presented. Assuming standard multi-sector hub site configuration with four sectors with alternating polarizations, and cross polarization uplinks and downlinks, the cumulative distribution of link availability in the system is calculated as a function of system loading, cross polarization rejection, and required C/(I+N) performance. Using standard methodology, fade and rain outages are also considered on every link. The results show that increasing antenna gain and cross polarization rejection increase system capacity. With an idealized system layout, and a C/(I+N) ratio of 15 dB, a system loading of greater than 90% of channels per sector is possible (a frequency reuse factor of nearly 4). For 64 QAM with a C/(I+N) ratio of 25 dB, this hub frequency reuse factor reduces to about 2.