This Small Business Innovation Research Phase I project investigates the performance and feasibility of a channel-hopping packet radio-base station. In the United States, a consortium of cellular service providers is building a nationwide mobile data network called Cellular Digital Packet Data (CDPD). By using existing 30 kHz radio frequency channels, CDPD provides a mobile data overlay on the existing cellular voice system. To exploit unused capacity, CDPD hops between idle voice channels. Base stations currently under development scan the available frequencies and select the idle channel that is expected to remain idle for the maximum length of time. This approach is far from optimal because it does not address co-channel interference effects. To improve throughput of hopping data channels, the base station should select the idle channel with the least co-channel interference. By doing so, a packet radio system can theoretically increase throughput by a factor of five. This project presents many technical challenges, including the need for a 12.5 MHz-wide digital receiver capable of acquiring and processing channel data in less than 10 milliseconds. The research objectives of this project are to demonstrate a factor of four improvement in throughput in Rayleigh fading, determine estimation accuracy, determine the impact of implementation losses, determine the performance of multiple hopping channels, and investigate efficient spectral estimation techniques.
