With the recent advances in semiconductor device technology and the FCC's approval of the unlicensed use of ultra-wideband systems, UWB development has moved from research labs and classified military projects to the commercial sector. UWB technology brings many opportunities as well as challenges to the world of wireless communications.
In this introductory chapter, we reviewed the history, background, and basic concepts of UWB communications. We identified the major advantages and challenges of this emerging technology and reviewed the funda mental differences between narrowband, wideband, and ultra-wideband communications. Also, we introduced the two UWB leading candidates for the IEEE 802.15.3a WPAN standard: single-band and multiband UWB approaches. We also discussed the current worldwide regulatory situation regarding UWB, as well as the FCC emission limits on UWB devices in the United States. Finally, we briefly explained the applications of UWB for military, government, and commercial uses. A comprehensive discussion of UWB applications and target markets is available in Chapter 5.