Code design for spectral separation in time hopping multiple access communication systems

Abstract

Ultra-wideband (UWB). also called Impulse Radio (IR), is a form of spread spectrum signaling by radiating trains of time-shifted pulses that are very short in time, usually in nanosecond. In this report, Time-Hopping (TH) Spread Spectrum (SS) technique is discussed. It is one of the spread spectrum schemes used for Ultra-wide band systems. Other schemes are Frequency Hopping (FH) and Direct Sequence (DS) Spread Spectrum. In Time Hopping (TH) Multiple Access (MA), each terminal sends signal at a unique time slot defined by the TH code assigned. A properly designed Time hopping code not only eliminates the effect of collisions in multiple access schemes but also smooths the Power Spectral Density (PSD) of the transmitted signals. In the frequency domain, it is possible to separate the spectral information of each operating terminal with the properly designed TH code.