A spread-spectrum system for indoor nonline-of-sight mobile applications

This paper describes a spread-spectrum system designed for indoor wireless applications with no direct path. The key element of the receiver is a differential phase shift keying (DPSK) surface acoustic wave (SAW) matched filter and its design is described. The excellent performance of such a system is displayed using the case of mobile robotics inside a nuclear plant. Good agreement with theoretical results is also illustrated. Finally we propose a bandlimited scheme allowing a very simple implementation of diversity with only one DPSK SAW demodulator.