Advanced Mobile Phone Service: The Cellular Test Bed

Bell Laboratories is engaged in an ongoing field studies program to characterize the performance of UHF cellular mobile telecommunications systems. This program, designated the Cellular Test Bed (CTB) in its present phase, evolved from fundamental investigations of propagation-related phenomena. The initial thrust of the field studies program was to expand the work of previous investigators in order to generate a modeling of the influences of the environment on UHF signal propagation between a land site and mobile unit. To accomplish this modeling, a specially instrumented vehicle and land transmitting stations were developed and installed in the Whippany, N.J. and metropolitan Philadelphia, Pa. areas to provide UHF signal propagation data. The stations were located in a variety of propagation environments typical of suburban and urban communities so that conclusions drawn from the data are applicable to the broad deployment requirements of a practical cellular system. 215 Specifically, in the first phase of the field experiments, statistics were generated on UHF path loss as a function of range, propagation environment, and antenna elevation. The tests furnished data to characterize environmental noise and the correlation properties of signals received at the mobile unit from transmitting antennas at widely separated land sites. The results of these early experiments supplied the information necessary to specify system radio-plan parameters affecting radio coverage and frequency reuse.