This paper reviews the state of the art of the technology based in channels of Ultra Wide band (UWB Ultra–Wideband) focusing on its regulation, standardization, basic applications, IEEE 802.15.4a channel model and simulation of the impulsive response of this type of channel. Also, it aims to introduce the reader to the technologies based on IR–UWB channels and the parameters for modeling and simulation of IEEE 802.15.4a UWB channel. PACS: 41.20.Jb, 42.25.Dd