Comparison of Mobile Radio Transmission at 150, 450, 900, and 3700 Mc

From the beginning of mobile radiotelephone services offered by the Telephone Companies, both "general" and "private-line" types, it has been apparent that the number of channel frequencies then allocated for these uses would not be sufficient to meet the service needs in the near future. The bulk of these needs will be for service in urban and suburban areas, where business activities are concentrated. These areas are now served on a few individual FM channels in the vicinity of 150 mc. However, a larger number of channels, needed to meet anticipated demands and to develop a more efficient system, are not to be found in the 106S MOBILE RADIO TRANSMISSION 1069 150 mc region. This space is already allocated fully and permanently to a variety of other services. In fact, this situation extends up to about 400 mc. The larger number of channels for these services apparently will have to be found, therefore, above 400 mc. However, it is essential to know whether these higher frequencies would be suitable for urban mobile telephone service, or whether there exists an upper limit to the suitable frequencies. In order to answer these questions, a series of tests has been made to compare the adequacy of coverage that could be provided at several representative higher frequencies. These tests were conducted in and around New York City. This location is considered to be typical of the larger metropolitan areas. THE PROBLEM OF EVALUATION