Scrambling Code Breaking the Trade-Off Between Repetition Factor and Frame Length in Time-Hopping Impulse Radio Ultra Wide Band

This paper investigates the signaling scheme of time-hopping impulse radio ultra wide band (TH-IR-UWB). With a simple repetition code and without scrambling code, at a given spreading factor and a given system load, a trade-off has to be done in the choice of the frame length and the repetition factor. If the repetition factor on frame length ratio is too small, multiuser interferences (MUI) are not Gaussian, if it is too high the MUI becomes Gaussian but its variance becomes too high also. We show how the introduction of a scrambling code breaks this trade-off, we can increase the repetition factor on frame length ratio without increasing the MUI variance. Thus we will see that such a scrambling code should be applied to UWB networks with high density of users and low data rates like ad-hoc sensor networks, as well as networks with higher data rate and small number of users.