Local multipoint communications systems (LMCS) field tests in Canada

The Communications Research Centre (CRC) conducted field tests on a pilot local multipoint communications system (LMCS) at 28 GHz, in a major urban centre in September of 1997. The coverage of two of four operational cells was studied. This system was configured to broadcast digital video and audio programs originating from a satellite signal. Measurements were taken at 395 sites within a 5-km radius to evaluate the system's availability. The availability is highly dependent on terrain, path clearance, and transmitter/receiver antenna height. Another noteworthy point is that, for both cells, there were sites available outside the anticipated 5-km radius. Measurements were done within clusters consisting of three-by-three test sites, spaced at a distance equal to one residential house, to simulate a real LMCS implementation case. The purpose of this test was to confirm that no large variations of the signal power after down conversion (SPAD) within a small area existed where there were no major blockage. From the results it can be noted that the SPAD variations are only a few dB within a cluster and that all the measured SPAD match closely with the calculated SPAD curves assuming free space propagation.