asakta-buddhih sarvatra . jitatma vigata-sprhah . . . . naiskarmya-siddhim paramam . sannyasenadhigacchati Detached by spiritual intelligence from everything controlling the mind, without material desires, one attains the paramount perfection in cessation of re- tions by renunciation. The Bhagvad Gita (18.49) Compared to traditional carrier-based, Ultra-Wide Band (UWB), or carrier-less, systems implement new paradigms in terms of signal generation and reception. Thus, designing an UWB communication system requires the understanding of how excess bandwidth and very low transmitted powers can be used jointly to provide a reliable radio link. UWB offers systems transceiver potential for very simple implementations. Comparison between UWB and traditional narrow-band systems highlights the following features: Large bandwidth enables very fine time-space resolution for accurate lo- tion of the UWB nodes and for distributing network time stamps. Very short pulses are effectively counter-fighting the channel effect in very dense multipath environments. Data rate (number of pulses transmitted per bit) can be traded with power emission control and distance coverage. Very low power density leads to low probability of signal detection and adds security for all the layers of the communication stack. Very low power density is obtained through radio regulation emission masks; UWB systems are suitable for coexistence with already deployed narrow-band systems.

Prof. Ramjee Prasad is the Director of the Wireless Centre at Aalborg University in Denmark. He recently won a distinguished "Nordic" award for research achievements in the field of wireless communications. Ramjee Prasad is editor-in-chief for our Wireless Personal Communication journal and has also published over 15 books, mostly with Artech House though he is now eager to start publishing more of his books also with Springer.