Ultra-Wide Band (UWB) is a wireless technology which exhibits unique features such as spectrum coexistence with other wireless services, RF front-end simplicity (enabling potential low cost terminals), good radio wave propagation (robustness against multi-path fading, material penetration) and high bitrate. Current UWB implementations target short-range ultra-high bitrate point-to-point wireless communication. UCELLS project will develop the required technology to enable the cellular operation of UWB transceivers. This cellular operation enables the seamless provision of UWB communication along a medium range user area, e.g. a whole office or home.Cellular operation of UWB transceivers requires the spectral coexistence of UWB wireless communications with other wireless licensed services operating in the same band. Strong concerns exist nowadays regarding this coexistence. These concerns are reflected in the strict maximum radiated power imposed by the Spectrum Regulation Agencies (e.g. FCC and ETSI) in current UWB regulation to avoid UWB-induced interferences.The cellular UWB technology in UCELLS guarantee that regulated radiation limits are meet in a given coverage area, despite a large number of UWB transmitters are in operation and/or the transmission limits are locally exceeded. In UCELLS radiated power limits could be locally "relaxed" in some frequency sub-bands, which is reflected it larger UWB range, higher bitrate and larger user capacity.UCELLS monitors spectral radiation limits at the cellular coverage area boundary by a real-time spectrum monitor. This system with unique features (large bandwidth, high dynamic range and good spectral resolution) is implemented using a photonic analogue-to-digital converter (Ph-ADC). The associated spectral analysis algorithms to optimise both the system performance and an efficient spectrum utilisation of cellular UWB communication are also developed in UCELLS.