Proceedings of the 12th annual international conference on Mobile computing and networking
Cross layer PHY-MAC protocol for wireless static and mobile ad hoc networks
EURASIP Journal on Advances in Signal Processing - Special issue on signal processing applications in network intrusion detection systems
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Limited channel spectrum and rapid growth in the number of wireless devices make the issue of efficient channel resource utilization in wireless networks critical. Additionally, with the growth of real-time applications, wireless networks that support quality of service (QoS) have also drawn a lot of attention. This dissertation focuses on the design of scheduling algorithms to improve channel utilization and to support differentiated service in wireless multihop networks. To improve the channel utilization, we discuss approaches along both the temporal dimension and the spatial dimension. In the temporal dimension, when two nodes are competing for the channel, their channel accesses are separated in time to ensure successful transmissions. As an improvement over the conventional approaches, we propose the application of "pipelining" techniques to medium access control (MAC) protocol design. Pipelining, which allows the execution of multiple tasks to overlap in time, can help to hide MAC overhead by overlapping it with useful packet transmissions, leading to improved channel utilization. In the spatial dimension, due to radio signal attenuation, two competing nodes separated in space can be allowed to transmit at the same time, using transmission rates suitable for their link qualities. Exploiting the fact that nodes in a wireless network compete for "space" to schedule their packet transmissions, we propose a new approach that adapts the "space" occupied by the transmissions, named "spatial backoff," to improve the channel utilization. In order to support differentiated service, the medium access control protocol must provide certain mechanisms to incorporate differentiated priority scheduling, such that higher priority traffic can be transmitted in preference to lower priority traffic. The "location dependent channel contention" and "hidden terminals" make priority scheduling significantly different from that in wireless LANs. In this dissertation, we also discuss issues related to priority scheduling in multihop networks. A priority scheduling protocol is proposed to ensure channel access privilege of high priority packets and to improve the channel utilization when high priority packets are not present.