Abstract
In this article, a comprehensive review of multiple access interference (MAI) avoidance/cancellation for impulse radio (IR) ultrawideband (UWB) systems is presented. First, interference avoidance through transmitter-side techniques for both synchronous and asynchronous communications are discussed. Later, interference cancellation schemes at the receiver are classified and analyzed under following categories: maximum likelihood methods, linear receivers, iterative/Turbo interference cancellation methods, blind/adaptive techniques, and other algorithms. More emphasis is given on MAI cancellation for time-hopping (TH) and direct-sequence (DS) IR-UWB. On the other hand, various algorithms that are already considered for DS code division multiple access (CDMA) systems are also discussed. The goal of the article is to have a compact reference on the current state-of-the-art in MAI avoidance/cancellation techniques for IR-UWB systems, to outline analogies and differences between IR-UWB and DS-CDMA approaches to handle the MAI, and to identify possible research directions.