Digital Wireless Communications

The world wide communications infrastructure is undergoing dramatic revision, with optic fiber providing virtually limitless bandwidth, and wireless communication connecting increasingly mobile users to that fiber backbone. However, cost-effective evolution to an information-rich society will require strong standardization of wireless communication technology. The United States gave birth to the spread spectrum technology embodied in the mobile telephony and personal communication service (PCS) standard IS-95, and three of the five major PCS consortia have recently adopted IS-95 as the basis for their service. The other two have selected wireless technology based on the International Standard GSM, which uses frequency-division/time-division multiplexing (FDM/TDM) rather than IS-95's code-division multiplexing (CDM) to share the linited spectrum resources among many mobile users This SBIR effort explores the relative sensitivity of these competing standards to cochannel interference. It investigates adapting a processing technique based on cyclostationary equalization, currently used to eliminate the impact of jamming in modems for military applications, to mitigate the interference sensitivity of IS-95. The Phase I SBIR effort will demonstrate how this technique can be integrated with commercial IS-95 modem technology to provide a seamless backward-compati ble interference mitigation solution. Phase II will demonstrate a fully functional IS-95 modem incorporating the new processing.