Channel Requirements for a Cordless Telephone Spectrum Allocation

Planning for a permanent cordless telephone spectrum allocation requires that the number of channels necessary to meet the long-term needs of cordless telephones be estimated. To provide the analytical basis for such an estimate, we determine the relationship between the number of channels available to cordless telephones and their performance in a suburban residential environment. Multiple cordless telephones in a community can use the same channel simultaneously, so performance ultimately will be limited by cochannel interference. We therefore develop a mathematical model of the carrier-to-interference ratio. This model accounts for shadowing, polarization, and multipath propagation effects observed in field measurements, as well as the random locations of cordless telephones. A performance measure is developed and evaluated for cordless telephones that can access all available channels and are operating in a suburban residential environment. The results indicate that for carrier frequencies in the low UHF band (300 MHz to 1 GHz), an allocation of 30-40 duplex channels can accommodate universal use of cordless telephones in that environment. For lower carrier frequencies, shadowing is less severe and fewer channels would be necessary. For example, at 50 MHz, 20 duplex channels would suffice.