Measurement-based estimates of bit-error-rate performance in urban LOS microcells at 900 MHz

Cumulative distribution estimates are presented for the one-second-average bit-error-rate (BER) which would be experienced on UHF links in a microcellular environment. It is assumed that users (subscribers) are moving at speeds ranging from quasi-stationary to 96 km/h. The authors concentrate on lineal microcells, in which there is always a line-of-sight path between the microcell and subscriber antennas, in addition to road-reflected and/or building-reflected rays. Using extensive UHF data collected in Manhattan, the signal and interference levels are characterized, point-by-point, for a subscriber moving in a lineal microcell. Combining these measurement-based characterizations with a mathematical model of modem performance, the cumulative distribution of the BER is computed. For moving subscribers, simple diversity reception gives large benefits in grade-of-service (percentage of time that the BER is below a specified threshold value) and uplink and downlink transmission qualities tend to be similar, with the latter being somewhat better. Performance estimates based on a multiray model are generally similar to those based on measured data and tend to be conservative