Cochannel isolation characteristics in an urban land mobile environment at 900 MHz

Field tests have been performed in various environments in the Chicago area to evaluate cochannel isolation characteristics. As cell sizes shrink in order to increase capacity, cellular systems must address cochannel isolation degradation associated with hostile environments and its effect on reuse, for both omnidirectional and directional antennas. Measurement results are reported on directivity distortion due to scattering by close-in buildings, median signal level variations with omnidirectional antennas, and lognormal shadowing characteristics in 'minicells'. Simulations of C/I (carrier/interference ratio) performance were performed using measured data, and results indicate that median signal level variations can degrade C/I by up to three times that caused by directivity distortion. >