A comparison of two systems for downlink communication with base station antenna arrays

We compare the performance of the downlink of two systems with antenna arrays at the base stations. One system uses a third of the available spectrum per cell 1/3, but reuses the channels three times within each cell. The other system reuses all the spectrum in all cells 1/1, but does not reuse channels within a cell. Thus, the maximum number of users in the two systems is the same. In order to account for the interference, the 1/3 system directs antenna pattern nulls against same cell cochannel users, while the 1/1 system directs nulls against cochannel users in other cells. The performances of the two systems are compared as a function of the azimuth angular width (seen from the base) of the multipaths generated at the mobile, using simulations and analytical derivations. The results herein indicate that the system with 1/1 reuse has a higher performance than the system with 1/3 reuse if fast intercell handover is used or if high dynamic range power control, nulling and synchronization is employed.