Ultra-wideband (UWB) technologies with higher data rates and lower transmission power over shorter ranges, have enabled a new set of applications in Wireless Personal Area Networks (WPANs). For example, UWB can offer data rates 50 to 500 times higher than the current WPAN technologies such as Bluetooth. This property makes UWB a primary candidate for indoor high-speed multimedia applications such as whole-house Internet Protocol Television (IPTV) and Personal Video Recorder (PVR). Lower power emission brings less interference to other devices, and larger bandwidth makes UWB less affected by interference from others, which are very attractive attributes in a household environment. However, the effective and efficient utilization of such high data rate wireless channel represents a new challenge to WPAN Media Access Control (MAC), especially for high quality video streaming applications. To meet the minimum bandwidth and maximum delay requirement for Quality-of-Service (QoS) guarantee, high-definition IPTV and PVR services usually need to reserve a certain amount of channel time for exclusive access in a dynamic manner, since the number of video flows may change over time in a piconet. WiMedia Alliances MAC protocols for UWB-based WPANs have become an international standard. The Distributed Reservation Protocol (DRP) is part of this standard that reserves the wireless channel on a slot-by-slot basis for different flows. However, not much work has been done on DRP reservation algorithms and their performance. In this research, we propose, analyze and evaluate two application-aware reservation algorithms. One algorithm allocates time slots based on the first-fit idea whereas the other takes one step further by doing a best-fit reservation according to the maximum tolerable delay bound. Our proposed algorithms try to find the best possible time slots for any requests with respect to the existing reservations in the piconet and those arriving later. With these algorithms, devices in the same piconet that have data to transmit can negotiate and reserve time slots based on their traffic specification and QoS requirement while following WiMedia MAC reservation policies. We analyze the reservation algorithms and policies with a tiered overflow model, and evaluate their performance with Network Simulator (NS-2 ) and an MPEG-4 video traffic generator. We further discuss the ways of improving video streaming quality and system resource utilization in UWB networks.

The IEEE 802.15.4 standard is a low-power, low-rate MAC/PHY standard that meets most of the stringent requirements of single-hop wireless sensor networks. Sensor networks with nodal populations comprised of thousands of devices have been envisioned in conjunction with environmental, vehicular, and military applications, to mention a few. However, such large sensor network deployments necessitate multi-hop support as well as low power consumption. In light of the standard's extremely limited joint support of the two aforementioned attributes, this thesis presents two essential contributions. First, a framework is proposed to implement a new IEEE 802.15.4 operating mode, namely the synchronized peer-to-peer mode. This mode is designed to enable the standard's low-power features in peer-to-peer multi-hop-ready topologies. The second contribution is a distributed Guaranteed Time Slot (dGTS ) management scheme designed to function in the newly devised network mode. This protocol provides reliable contention-free access in peer-to-peer topologies in a completely distributed manner. Assuming optimal routing, our simulation experiments reveal perfect delivery ratios as long as the traffic load does not reach or surpass its saturation threshold. dGTS sustains at least twice the delivery ratio of contention access under sub-optimal dynamic routing. Moreover, the dGTS scheme exhibits minimum power consumption by eliminating the retransmissions attributed to contention, which in turn reduces the number of transmissions to a minimum. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2007-10-25 14:55:36.811