Medium access control in cognitive impulse radio UWB networks

Impulse Radio Ultra Wide Band (IR-UWB) is a candidate technology in the deployment of cognitive underlay networks. Medium Access Control protocols for IR-UWB networks were however conceived in the past moving from considerations related to performance of the UWB networks, rather than from the need to coexist with other wireless systems. This chapter analyses existing MAC protocols for low rate IR-UWB networks, and focuses on two specific protocols: the (UWB)2 MAC, and the MAC of the IEEE 802.15.4a standard that leveraged the access strategy proposed by (UWB)2. Characteristics of the two MAC protocols are reviewed, and the performance of the (UWB)2 MAC is analysed by means of computer simulations, adopting an accurate model for Multiple User Interference. Results confirm the suit- ability of the (UWB)2 protocol for low rate IR-UWB networks. Finally, the chapter discusses potential improvements and adaptations to be introduced for (UWB)2 to meet the coexistence requirements imposed by operation of the UWB network in a cognitive fashion.