Devan Rehunathan

Exploiting Self-Reported Social Networks for Routing in Ubiquitous Computing Environments

Mobile, delay-tolerant, ad hoc and pocket-switched networks may form an important part of future ubiquitous computing environments. Understanding how to efficiently and effectively route information through such networks is an important research challenge, and much recent work has looked at detecting communities and cliques to determine forwarding paths. Such detected communities, however, may miss important aspects. For instance, a user may have strong social ties to another user that they seldom encounter; a detected social network may omit this tie and so produce sub-optimal forwarding paths. Moreover, the delay in detecting communities may slow the bootstrapping of a new delay-tolerant network. This paper explores the use of self-reported social networks for routing in mobile networks in comparison with detected social networks discovered through encounters. Using encounter records from a group of participants carrying sensor motes, we generate detected social networks from these records. We use these networks for routing, and compare these to the social networks which the users have self-reported on a popular social networking website. Using techniques from social network analysis, we find that the two social networks are different. These differences, however, do not lead to a significant impact on delivery ratio, while the self-reported social network leads to a significantly lower cost.

A comparison of TCP behaviour at high speeds using ns-2 and Linux

There is a growing interest in the use of variants of the Transmission Control Protocol (TCP) in high-speed networks. ns-2 has implementations of many of these high-speed TCP variants, as does Linux. ns-2, through an extension, permits the incorporation of Linux TCP code within ns-2 simulations. As these TCP variants become more widely used, users are concerned about how these different variants of TCP might interact in a real network environment -- how fair are these protocol variants to each other (in their use of the available capacity) when sharing the same network. Typically, the answer to this question might be sought through simulation and/or by use of an experimental testbed. So, we compare with TCP NewReno the fairness of the congestion control algorithms for 5 high-speed TCP variants -- BIC, Cubic, Scalable, High-Speed and Hamilton -- on both ns-2 and on an experimental testbed running Linux. In both cases, we use the same TCP code from Linux. We observe some differences between the behaviour of these TCP variants when comparing the testbed results to the results from ns-2, but also note that there is generally good agreement.

Enabling Mobile Networks through secure naming

Mobile Networks are increasingly important in land-, sea-and air-based military scenarios. The interest in supporting network mobility for Internet Protocol (IP) networks has led to the Network Mobility (NEMO) protocol extensions being proposed for IP within the IETF. These extensions are based on the work already completed on host mobility for Mobile IP (MIP). The current work is based on the use of software agents: a Home Agent (HA) intercepts packets destined for the addresses in the mobile network and uses an IP-in-IP tunnel to send the packets to the Mobile Router (MR) located at a Care of Address (CoA), which terminates the tunnel. As the mobile network moves to new IP networks, the MR updates the HA with its new CoA. While this tunnelling approach represents a sound engineering solution for backwards compatibility, and is the only one that has been pursued within the IETF, it has seen little deployment, either in support of mobile hosts or mobile networks. We make the case for an alternative approach based on secure naming. We make a comparison in operation with the current tunnelling-based approach, both in architecture and by analysis of protocol operation. Our initial analyses indicate that a naming-based approach shows promise as a viable alternative to a tunnelling-based approach, and could offer other architectural benefits.

vNurse: Using virtualisation on mobile phones for remote health monitoring

We present vNurse, a system based on a smartphone platform that permits comprehensive, secure and modular patient remote monitoring outside a clinical environment, e.g. in the home. Using both virtualisation of the phone OS and virtual mobile networks of sensors with full Internet Protocol (IP) connectivity, we enable real-time remote sensor readings of patient Wireless Body Area Networks (WBANs) to be stored, processed and forwarded securely to healthcare practitioners based at clinical sites, while patients are remote or mobile.

A comparative assessment of routing for mobile networks

Wireless mobile devices are becoming increasingly prevalent in society. As a result, aggregation of network connectivity through the use of mobile networks is becoming increasingly relevant to service providers as well as for mobile users. The current approach being pursued within the IETF Mobile Extensions for IPv6 (MEXT) WG, is based on the Network Mobility (NEMO) architecture. NEMO uses IP-in-IP tunnelling for providing mobile network capability on an existing IPv6 network. This approach can result in non-optimal routing between source and destination nodes. Other proposals such as OptiNets extend NEMO and try to address issues such as sub-optimal routing. There are alternative approaches also being proposed, such as the Identifier Locator Network Protocol (ILNPv6), which is based on the use of naming, to enable a flexible and integrated mobile network capability based on IPv6.We have conducted a comparative analysis of the cost of providing optimal routing, in terms of packet and bandwidth overhead, based on an emulation, using data from the London Circle Line metropolitan railway as a scenario. Our analysis shows that these different approaches to mobility offer significantly different performance trade-offs in routing for mobile networks, depending on the constraints of the network scenario.

Application of virtual mobile networking to real-time patient monitoring

We aim to merge the benefits of network mobility and virtualisation to provide a simple, mobile and secure method for providing mobile network (as opposed to mobile host) platforms. We demonstrate our approach by showing the use of a mobile network of sensors and wide area connectivity for maintaining and managing a Wireless Body Area Networks (WBAN) for healthcare. WBANs are a mature field of research, where the challenges and applications have been explored for quite some time. One of the most promising applications for WBANs is healthcare. Wireless sensors are used to monitor patient health statistics and activity. With the ubiquity of wireless mobile personal devices (such as smart phones), their increased CPU and power capability, the feasibility of using them to build mobile network platforms is increasingly possible. In this paper we describe our novel approach, which is to utilise, through virtualisation, an individuals smartphone not only as a mobile router that manages his personal mobile network, but also as a platform to host his WBAN.

Comparing network protocols via elimination of MAC/PHY effects

Outside simulation, the study of mobile network protocols is not trivial and the standard approach usually involves building a testbed and populating it with the relevant entities. While this approach, provides real-life results, it is time consuming and resource intensive. We propose an alternative approach that can be used to compare mobile network protocols with a minimum amount of resources. Our solution explores the possibility of discounting physical layer effects entirely, when doing a comparative analysis of two mobile network protocols. In this paper, we document and discuss our efforts to check if this method is feasible.

Mobile Networks: Naming vs. Tunnelling

Using data of passenger numbers and train schedules from the London Underground metropolitan railway system, we compare a Tunnelling-based to a Naming-based approach for supporting mobile networks. We show that, in terms of packet overhead, a naming based approach may have similar performance overhead to a tunnelling approach, and so may offer a viable alternative, whilst also offering other benefits.