A low-complexity multiuser detector for Time-Hopping Impulse-Radio systems

For a conventional time-hopping impulse-radio (TH-IR) system, all the pulses corresponding to the same information symbol are transmitted with the same sign. In this paper, we consider a slightly modified TH-IR system in which each user will be assigned a randomly generated binary sequence that modulates the transmitted pulses. We further present a detector based on the likelihood ascent search algorithm (LAS). It is shown that for TH-IR system with large number of users (orders of hundreds to thousands), this detector can approach the single-user performance at an average per bit complexity linear in the number of users.