DELAY SPREAD MEASUREMENTS FOR THE DIGITAL CELLULAR CHANNEL IN TORONTO

This paper describes a set of measurements performed in the Toronto ar ea, in order to assess the impact of multipath propagation on the perf ormance of the TIA IS-54 digital standard. Five existing cells were sy stematically surveyed: two in downtown Toronto, two in the suburbs, an d one in a suburban/rural area. A sweeping correlator apparatus with a 0.1 mu s resolution and 910 MHz, carrier frequency, and an omnidirect ional antenna was used. Tn one of the tells, the measurements were rep eated with a 60 degree beamwidth directional antenna. A fairly sophist icated thresholding technique was applied in order to reduce the impac t of noise. Generally, the measurements with the omnidirectional anten na exhibit multipath propagation with considerably smaller excess dela ys than some reported recently, but are consistent with earlier result s obtained in the U.S. and Europe. Sectorization was found to consider ably reduce the multipath effects. Very large delay components appear to be due mostly to the combination of large transmitter-receiver dist ances and a large degree of shadowing, and could probably be avoided t o a large extent by standard cellular engineering techniques. In view of these results, it seems that the long delay (high selectivity) prob lem has been somewhat overemphasized in the past, at least for areas l ike Toronto. Problems associated with short delays (flat fading), on t he contrary, appear to have been underestimated in the case of dense u rban environments.