A Hybrid M-Ary Modulation Scheme for Time Hopping UWB Communication Systems

This paper describes a combined modulation scheme for time hopping ultra wideband (TH-UWB) radio systems based on biphase shift keying (BPSK), orthogonal pulse position modulation (OPPM) and pulse shape modulation (BPSM). A set of M = 2^k symbols are constructed by using L = 22^l orthogonal pulse positions and N = 22^k-l-1 biorthogonal pulses, where k and l are nonnegative integers such that 0 ≤ l ≤ k - 1. The selection of number of pulse positions and pulses depend on the system performance and the availability of orthogonal pulses with estimable auto-correlation properties. The proposed scheme achieves higher data rate by introducing more number of orthogonal pulses in the same pulse repetition interval. It also reduces the system complexity by half by introducing antipodal version of orthogonal pulses. The proposed transmission scheme is analyzed through computer simulations in the presence of multipath channel.