1 DESIGN ISSUES IN MULTIMEDIA TRANSMISSION OVER COGNITIVE RADIO UWB MULTIBAND OFDM SYSTEM Norazizah M. Aripin, Rozeha A. Rashid, Norulhusna Ahmad, Aida E.M Hamzah, Norsheila Fisal & Sharifah K. Syed –Yusof 1.1 INTRODUCTION Ultra-wideband (UWB) and cognitive radio are two exciting technologies that offer new approaches to spectrum usage. In wireless communication today, spectrum partitioning is overcrowded due to explosive growth of numerous applications and hence, demands for spectral resource increase significantly. However, the majority of these spectrum partitioning are often inefficiently utilized. Cognitive Radio (CR) technology takes advantage of the spectrum holes by intelligently identifying and using them, and possibly releasing it when required by the primary users (PU). CR is able to intelligently adapt its transmission on the unlicensed frequency band such that the interference to the primary users is avoided or limited to an acceptable level. Researches in CR are mainly evolved around the following technical issues in enabling spectrum-aware communication protocols [4]: a) How to sense spectrum and model the behaviour of the PUs. b) How to manage and decide the available spectrum to meet user QoS requirements. These management functions