Synchronization of spread spectrum communication systems using signal design.

摘要

This dissertation addresses the problem of synchronization in a multi-user communication system using a signal design approach. Spread spectrum signal design is used to take advantage of a unique narrowband auto-ambiguity function property, traceability, which can be used to reduce the synchronization time and the number of false synchronization events. Traceability as a narrowband auto-ambiguity function property is fully developed and measured for a variety of spread spectrum signals. Frequency hop spread spectrum signals demonstrate traceability by allowing for direct control over their narrowband auto-ambiguity function properties. Phase modulation techniques such as direct sequence can not be used to control the energy spreading in the narrowband auto-ambiguity function.;The research is comprised of developing the traceability concept, analyzing the traceability of various spread spectrum signals, and quantifying the improvement in synchronization performance of a simple tracing search algorithm. The traceability property is defined using an approximation of the narrowband auto-ambiguity function. The traceability of various frequency hopped and direct sequence spread spectrum signals is evaluated. The linear congruence code family is found to be maximally traceable. A synchronization scheme that takes advantage of traceability is developed and simulated to determine the effectiveness of traceability. Performance results show that the synchronization time is reduced by a factor of 2 and false synchronization events by a factor of 10. Synchronization time can be further reduced by a factor of 10 if the local oscillator error budget is carefully specified in a communications system.