Design and performance analysis of TH sequences for UWB-IR systems

Time hopping (TH) is commonly used with impulse radio (IR) based ultrawideband (UWB) systems as a multiple access scheme. In such systems, TH codes must he carefully designed to optimize the system performance. In this paper, TH code design for both synchronous and asynchronous UWB-IR systems are studied. For synchronous systems, a novel code assignment algorithm that depends on the number of users and delay spread of the channel is proposed. Then, the proposed codes are extended to quasi-synchronous scenarios. For asynchronous systems, frequency hopping (FH) codes obtained by finite field theory are applied to TH-IR, and their autocorrelation and crosscorrelation properties are investigated. A multiuser performance analysis method is proposed which makes use of code correlation characteristics.