Design considerations in cross layer framework for cognitive UWB

Abstract

Ultra-wideband (UWB) and cognitive radio (CR) are two exciting technologies that offer new approaches to exploit the existing wireless spectrum opportunistically to overcome the limited available spectrum and the inefficiency in the spectrum usage. In Cognitive Ultra Wideband (C-UWB) system which utilizes low power transmission, the key challenge in enabling multimedia transmission lies on the dynamic allocation of network resources among users experiencing time-varying channel conditions and traffic characteristics while satisfying certain quality of service (QOS) requirements. This paper presents several key design considerations at the physical, MAC and application layer that need to be considered in cross layer design framework for C-UWB. At the physical layer, analysis on Multi-band Orthogonal Frequency Division Multiplexing (MB-OFDM) under several UWB channel conditions is presented. Multidimensional turbo product coding (MDTPC) is proposed to support video application due to its ability to support high data rate as well as BER improvement. Signal-to-noise ratio (SNR) condition and sensing time are taken into account as bridging parameters between the physical layer and the media access control (MAC) to optimize wireless resource allocation. Some preliminary result on the impact of resource allocation at the MAC to the video quality is also analyzed