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PhD in the area of reliable communications in mobile ad hoc networks

The PhD student will work on reliable communications, including:

  • Theoretical study on topology control and network connectivity for distributed mobile ad hoc network;
  • Algorithms for reliable and optimal path selection in the presence of multiple channels in wireless ad hoc networks;
  • MAC layer algorithms/mechanisms for QoS enhancements to existing IEEE 802.11-based WLANs;
  • Radio resource management and scheduling considering the dynamics of radio channels;
  • A prototype demonstrator for reliable multi-hop ad hoc communications.

Background and State-of-the-art

Reliability in fixed communication networks has been studied for many years. To provide reliable communication links/paths in wireless networks, however, becomes a challenging task. When heterogeneous wireless networks co-exist, the users should be offered reliable communication via one of the connected wireless networks. In the context of mobile ad hoc networks operated in a distributed manner, the reliability problem becomes how to find a reliable or robust peer-to-peer link between the source and the destination nodes. From the perspective of the SWACOM project, there are three major aspects related to reliable ad hoc communications. The first aspect is more theoretical-oriented, where the problem of network connectivity and topology control are studied using for example the graph theory. The second aspect of ad hoc networks deals with the problem of how to find a robust path with respect to link reliability, instead of using the traditional shortest path criterion. The third aspect of ad hoc communications assumes that each station is able to cope with several parallel wireless channels. This will soon be realistic given the maturity of the MIMO technology. In this case, how to provide a reliable path among all available channels becomes an interesting topic.

In the past 2~3 years, a few high-quality papers, e.g., [7], within the aforementioned first aspect have been published. Less attention has been devoted to the two other aspects. We have conducted some preliminary work within the topic of link reliability in mobile ad hoc networks. More insight work is expected.

Another aspect with this topic is related to QoS provisioning in wireless networks. From the perspective of the SWACOM project, we divide the QoS and resource management research into three sub-topics. 1) QoS provisioning in point-to-point communications while the time-variant channel condition is taken into account; 2) QoS provisioning in point-to-multipoint communications, e.g, typical WLANs scenarios, while multiple users are accessing the shared channel; 3) QoS provisioning in peer-to-peer communications, e.g. typical in ad hoc networks, where the architecture of the networks itself is dynamic. At the present stage, some work has been done regarding the aforementioned point 1). But little attention has been received at even higher frequencies, e.g. mm wavelength channels that are likely potential channels for wideband services in future wireless networks. Regarding point 2), lots of work has been done especially within the IEEE 802.11 committee. However, further enhancements are definitely necessary even after the newly ratification of the IEEE 802.11e standard in April 2005 [9][10]. The third point, QoS in ad hoc networks, is the most challenging task and is far from being mature. Due to the capacity fluctuation and the topology change of an ad hoc network, providing end-to-end QoS in MANETs becomes extremely difficult. As pointed out in [13], so far, no techniques proved to be satisfactory with respect to providing QoS in ad hoc networks, although there are approaches like SWAN [11] and QoS routing [12].

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Page last modified on January 05, 2006, at 10:42 AM EST