Multi-user capacity of M-ary PPM ultra-wideband communications

Abstract

We study the information theoretic capacity of M-ary pulse position modulation (PPM) ultra-wideband (UWB) communications for the multi-user channels. Under certain assumptions, the multiple-access interference component at the receiver is modeled as Gaussian. An expression for the signal-to-noise ratio is developed for UWB utilizing rectangular pulses. The information theoretic capacity of the UWB system is studied as a function of number of users. A closed form expression and a lower bound are found for the case of binary PPM. An upper bound on the aggregate capacity is found for the case of large number of users.