Impulse radio multiple access through ISI channels with multi-stage block-spreading

Impulse radio (IR) has received increasing interest for multiple access (MA). Operating in dense multipath environments. IRMA systems are affected by the multiple user interference (MUI) and intersymbol interference (ISI). Analog IRMA utilizes random time-hopping codes to mitigate such adverse effects statistically. In this paper, we develop an all-digital IRMA scheme that relies on multi-stage block-spreading (MS-BS) to eliminate MUI deterministically, regardless of ISI multipath effects. Unlike conventional IRMA systems. our proposed MS-BS-IRMA system exhibits no degradation in performance when accommodating a large number of users.