Algorithmic and practical foundations of mobile networking

Lead Research Organisation: University of Cambridge
Department Name: Computer Laboratory

Abstract

In recent years wireless network technology has gained tremendous importance. It not replaces only more and more so far 'wired' network installations but also opens new dimensions in the availability of high network connectivity in various scenarios. In many application areas the integration of wireless communication in particular together with autonomous sensing devices leads to an improved quality of service due to the immediate availability of measurements and data about the current mode of operation. The goal of this proposal is to investigate different approaches that can improve the performance of ad hoc networks. A wireless ad hoc network consists of several transceivers (nodes) located in the plane, communicating by radio. Unlike wired networks, in which the link topology is fixed at the time the network is deployed, wireless ad-hoc networks have no fixed underlying topology. In addition, the relational disposition of wireless nodes is constantly changing. The temporary physical topology of the network is determined by the distribution of the wireless nodes, as well as the transmission range of each node. The ranges determine a directed communication graph, in which the nodes correspond to the transceivers and the edges correspond to the communication links.
Topology control is to allow each node in the network to adjust its transmitting power so that a good network topology can be formed. There are many possible metrics to measure the efficiency of the constructed topology. To increase the longevity of such networks, an important requirement of topology control algorithms is to achieve the desired topology by using minimum energy consumption. To speed up the performance of routing algorithm we aim to produce a communication graph of bounded diameter and low interference levels. On the other hand, from the user's perspective, for already determined network topology, we want to identify the ``important'' places in the network in terms of robustness (failure of some node may lead to disconnected network), energy efficiency (some parts of network might be wasteful
in terms of energy), and scheduling (nodes may have many common neighbors which causes many interferences).
The main goal of this proposal is to design efficient solutions for topology construction of wireless ad hoc networks and to recognize important topology parts, taking into account various parameters altogether: energy, transport, schedule length, lifetime, hop-diameter and interference levels.

Planned Impact

Having been constructed from a group of mobile devices, an ad-hoc grid would allow the networked devices to accomplish a specific mission that maybe beyond an individual's computing or communication capacity. Examples of applications of mobile ad-hoc networks can be disaster management, wildfire fighting, and health care emergency. In health care several diseases and medical conditions require constant monitoring of physiological signals and vital signs on daily bases, such as diabetics, hypertension and etc. In order to make these patients capable of living their daily life it is necessary to provide a platform and infrastructure that allows the constant collection of physiological data even when the patient is not inside of the coverage area. The data must be rapidly "transported" to designated medical care givers. The problem is particularly severe in case of emergencies (e.g. natural disasters or hostile attacks) when the communications infrastructure (e.g. cellular telephony, WiFi public access, etc) has failed or is totally congested. The ad hoc networks will provide automatic control and therapy of the patients. In education sector, e-learning is of an increasing importance in modern education systems. One of the most important strategies for mobile e-learning is to focus on ubiquitous learning, communication in dialogues, and connectivity to meet the arising community aspects of learning platforms. With the combination of decentralized synchronization processes and a fixed synchronization point, ad hoc networks cover all issues for modern mobile e-learning environments. In commercial sector, ad hoc networks can be used in emergency/rescue operations for disaster relief efforts, e.g. in fire, flood, or earthquake. Emergency rescue operations must take place where non-existing or damaged communications infrastructure and rapid deployment of a communication network is needed. Information is relayed from one rescue team member to another over a small handheld. Other commercial scenarios include e.g. ship-to-ship ad hoc mobile communication, law enforcement, etc.
In media and entertainment sector, short-range mobile ad hoc networks can simplify the intercommunication between various mobile devices (such as a PDA, a laptop, and a cellular phone). Tedious wired cables are replaced with wireless connections. Such an ad hoc network can also extend the access to the Internet or other networks by mechanisms e.g. Wireless LAN (WLAN), GPRS, and UMTS. Daily news, videos and music can be requested from everybody and from every (connected) place in the world. All said above will add a tremendous impact on UK excellence and UK competitiveness in socio-economic and environmental fields. Also, since the energy conservation in mobile ad hoc networks is of paramount importance because most mobile nodes usually have very limited energy supply, our research on energy conservation, i.e., how to expend the energy resources in the network more frugally and evenly so as to prolong the network lifetime will show new, pioneering ways of improving the performance of networks.

Of course, UK is very strong in Wireless Networking, but the area moves fast and requires good theory and practice to continue to be pushed forward together. Energy considerations are also non-trivial, and while we've worked hard in the past to reduce power consumption in traditional wired and wireless networks, further future gains will need more radical ideas, such as some of the proposed work here. This is vital for UK to retain its leads in the area.

Publications

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Description Found a new way to minimise energy use for routing messages in ad hoc radio systems
Exploitation Route Optimising sensor systems which use multihop radio nets to report values is becoming more and more common in smart homes and smart cities-- techniques for optimising power use are important practically.
Sectors Digital/Communication/Information Technologies (including Software)