9423958 Jacobsmeyer This Small Business Innovation Research Phase II project investigates the performance and feasibility of an adaptive data rate modem for wireless packet radio networks. 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 combat the effects of multipath fading, CDPD uses a (63,47) Reed-Solomon code over GF(64). This code cannot correct all the errors that occur during the long, deep fades that occur on the mobile radio channel. A new technique, proposed herein, adapts the information data rate to the time-varying signal to noise ratio. Past research has shown that in theory, this technique can improve throughput of CDPD by a factor of five. The research objectives of this project are to construct a hardware prototype modem and demonstrate a factor of four improvement in throughput in Rayleigh fading. The prototype will be based on the AT&T DSP32C floating point signal processor and will be tested using an HP11759C Fading Channel Simulator. The principal commercial applications of this research are wireless multiple access communication networks, including cellular radio, mobile satellite and wireless local area networks. The primary benefit of the proposed research is more economical use of cellular radio base stations and mobile terminals, resulting in more affordable mobile data service for the US consumer.
