We describe protocol features to provide both Identity Privacy and Location Privacy at the network layer that are truly end-to-end, strengthening the trust model by constraining the boundary of trust to only the communicating parties. We show that Identity Privacy and Location Privacy can be provided by changing only the addressing model, whilst still remaining compatible with IPv6. Using the Identifier-Locator Network Protocol (ILNP), it is possible to use ephemeral end-system ILNP Node Identity (NID) values to improve identity privacy. Using the ILNP Locator values with dynamic bindings, it is possible to use multiple IPv6 routing prefixes as network Locator (L64) values to provide (topological) location privacy. This is achieved: (a) whilst maintaining end-to-end state for transport protocols, without proxies, tunnels, or gateways at the transport layer or application layer; and (b) without the use of cryptographic techniques, so performance is not impacted.

As the use of mobile devices and methods of wireless connectivity continue to increase, seamless mobility becomes more desirable and important. The current IETF Mobile IP standard relies on additional network entities for mobility management, can have poor performance, and has seen little deployment in real networks. We present a host-based mobility solution with a true end-to-end architecture using the Identifier-Locator Network Protocol (ILNP). We show how the TCP code in the Linux kernel can be extended allowing legacy TCP applications that use the standard C sockets API to operate over ILNP without requiring changes or recompilation. Our direct testbed performance comparison shows that ILNP provides better host mobility support than Mobile IPv6 in terms of session continuity, packet loss, and handoff delay for TCP.

We provide an empirical evaluation of an IEEE 802.11ac Wireless Local Area Network (WLAN) cell with Multiple User Multiple Input Multiple Output (MU-MIMO) technology. We conducted our experiments on a testbed comprising consumer equipment under different office scenarios using 40MHz and 80MHz channels. This is the first performance study of MU-MIMO with 802.11ac in an operational scenario using a commercial access point. We find that, for clients that do not support MU-MIMO, operating in a cell that has MU-MIMO enabled may result in reduced performance.

The increases demand for communications and Internet access makes Wireless Local Area Networks (WLANs) one of the most popular solutions for network connectivity. In this paper, we examine the performance and the energy efficiency of WLANs in 2.4 GHz and 5 GHz and discuss paths for upgrading. Our results show that it is worth upgrading to the 5 GHz bands from the 2.4 GHz band for 802.11n, especially for applications that are sensitive to packet loss. We also show that it is little benefit in upgrading from 802.11n 5 GHz to its successor 802.11acin terms of performance and energy efficiency. We consider overall performance as well as the energy efficiency of 802.11n2.4 GHz, 802.11n 5 GHz and 802.11ac protocols, all with 40MHzchannels, to give a typical 802.11 office scenario. It is clear that802.11ac can achieve slightly higher throughput compared to802.11n for flows of large packets. However, the comparatively small benefits of 802.11ac may not justify the cost of buying and deploying new equipment for the upgrade.

We describe a user study of a mHealth prototype system based on a wellbeing scenario, exploiting the quantified-self approach to measurement and monitoring. We have used off-the-shelf equipment, with opensource, web-based, software, and exploiting the increasing popularity of smartphones and self-measurement devices in a user study. We emulate a mHealth scenario as a pre-clinical experiment, as a realistic alternative to a clinical scenario, with reduced risk to sensitive patient medical data. We discuss the efficacy of this approach for future mHealth systems for remote monitoring. Our system used the popular Fitbit device for monitoring personal wellbeing data, the Diaspora online social media platform (OSMP), and a simple Android/iOS remote notification application. We implemented remote monitoring, asynchronous user interaction, multiple actors, and usercontrolled security and privacy mechanisms. We propose that the use of a quantified-self approach to mHealth is particularly valuable to undertake research and systems development.

Video is the most prevalent traffic type on the Internet today. Significant research has been done on measuring user's Quality of Experience (QoE) through different metrics. We take the position that energy use must be incorporated into quality metrics for digital video. We present our novel, energy-aware QoE metric for video, the Energy-Video Index (EnVI). We present our EnVI measurements from the playback of a diverse set of online videos. We observe that 4K-UHD (2160p) video can use ~30% more energy on a client device compared to HD (720p), and up to ~600% more network bandwidth than FHD (1080p), without significant improvement in objective QoE measurements.

Seamless host mobility has been a desirable feature for a long time, but was not part of the original design of the Internet architecture or protocols. Current approaches to network-layer mobility typically require additional network-layer entities for mobility management, which add complexity to the current engineering landscape of the Internet. We present a host-based, end-to-end architecture for host mobility using the Identifier-Locator Network Protocol (ILNP). ILNP provides mobility support as a first class function, since mobility management is controlled and managed by the end-systems, and does not require additional network-layer entities. We demonstrate an instance of ILNP that is a superset of IPv6 - called ILNPv6 - that is implemented by extending the current IPv6 code in the Linux kernel. We make a direct comparison of performance of ILNPv6 and Mobile IPv6, showing the improved performance of ILNPv6.

In mature wireless LAN (WLAN) deployments, we show that introducing 802.11ac could have little benefit compared to existing 802.11n deployments. Using a testbed with common characteristics for a WLAN deployment, we compare throughput for 802.11ac and 802.11n (in both 5GHz and 2.4GHz bands). We find that 802.11ac has lower throughput than for 802.11n for our testbed configuration. We also provide an evaluation of energy usage for 802.11ac and 802.11n.

We show that the Datagram Congestion Control Protocol (DCCP) provides ~10% - ~40% greater energy efficiency than the User Datagram Protocol (UDP) in a wireless LAN (WLAN) client. Our empirical evaluation uses a test bed comprised of consumer components and open source software to measure typical performance that can be expected by a user, rather than highly-tuned performance which most users will not be able to configure. We focus our measurements on a scenario using IEEE 802.11n at 5GHz as energy efficiency will be particularly important to mobile and wireless users. We consider overall performance as well as the energy efficiency of the protocol usage to give a rounded comparison of UDP and DCCP. Overall, we see there would be great benefit in many applications using DCCP instead of UDP.

Host multihoming allows individual hosts to be multiply connected to the network, e.g. by concurrent use of two network prefixes, each network prefix tied to a separate network interface. Such multihoming capability improves the host's ability to implement such features as load-balancing, fail-over and multi-path transport protocols. However, IP does not directly support host multihoming today. The Identifier / Locator split solution space is seen as one way for reducing such negative impact. We present an evaluation of host-multihoming as a prototype implementation of the Identifier Locator Network Protocol (ILNP) on FreeBSD, as a superset of IPv6 - called ILNPv6. We demonstrate load-balancing using ILNPv6 multihoming and compare performance with IPv6 forwarding at the end host.

The quantified self is a key enabler for mHealth. We propose that a wellbeing remote monitoring scenario can act as a suitable proxy for mHealth monitoring by the use of an online social network (OSN). We justify our position by discussing the parallelism in the scenario between purpose-driven wellbeing and mHealth scenarios. The similarity between these two scenarios in terms of privacy and data sharing is discussed. By using such a proxy, some of the legal and ethical complexity can be removed from experimentation on new technologies and systems for mHealth. This enables technology researchers to carry out investigation and focus on testing new technologies, system interactions as well as security and privacy in healthcare in pre-clinical experiments, without loss of context. The analogy between two purpose-driven scenarios, i.e. fitness monitoring in wellbeing scenario and remote monitoring in mHealth, is discussed in terms of a practical example: we present a prototype using a wellbeing device - Fitbit - and an open source online social media platform (OSMP) - Diaspora.

We propose the use of an open and publicly accessible online social media platform (OSMP) as a key component for ubiquitous and personal remote health monitoring. Remote monitoring is an essential part of future mHealth systems for the delivery of personal healthcare allowing the collection of personal bio-data outside clinical environments. Previous mHealth projects focused on building private and custom platforms using closed architectures, which have a high cost for implementation, take a long time to develop, and may provide limited access and usability. By exploiting existing and publicly accessible infrastructure using an OSMP, initial costs can be reduced, at the same time as allowing fast and flexible application development at scale, whilst presenting users with interfaces and interactions that they are familiar with. We survey and discuss suitability of OSMPs in terms of functionality, performance and the key challenge in ensuring appropriate levels of security and privacy.

Allowing digital video users to make choices of picture size and codec would significantly reduce energy usage, electricity costs and the carbon footprint of Internet users. Our empirical investigation shows a difference of up to a factor of 3 in energy usage for video decoding using different codecs at the same picture size and bitrate, on a desktop client system. With video traffic already responsible for the largest and fastest growing proportion of traffic on the Internet, a significant amount of energy, money and carbon output is due to video. We present a simple methodology and metrics that can be used to give an intuitive, quantitative and comparable assessment of the energy usage of video decoding. Providing energy usage information to users would empower them to make sensible choices. We demonstrate how small energy savings for individual client systems could give significant energy savings when considered at a global scale.

Alerts are an essential part of future remote health monitoring. We assess the feasibility of leveraging online social media for such capability to enable the delivery of healthcare outside clinical sites. We have implemented medical alerts triggered by bio-data and notifications of management-related actions in relation to the operation of an example heart-monitoring application. We have examined the suitability of online social media platforms using Facebook. A Facebook application was developed to deliver configurable alerts to four different actor viewpoints in a carer network; the patient; the doctor in charge; the professional carer; and a family member of the patient. The suitability of the application was analysed as well as an initial examination of the reliability of alert delivery. We conclude that online social media platforms could offer suitable platforms for alerts in remote health monitoring.

We have investigated the scope for enabling WLAN applications to manage the trade-off between performance and energy usage. We have conducted measurements of energy usage and performance in our 802.11n WLAN testbed, which operates in the 5 GHz ISM band. We have defined an effective energy usage envelope with respect to application-level packet transmission, and we demonstrate how performance as well as the effective energy usage envelope is effected by various configurations of IEEE 802.11n, including transmission power levels and channel width. Our findings show that the packet size and packet rate of the application flow have the greatest impact on application-level energy usage, compared to transmission power and channel width. As well as testing across a range of packet sizes and packet rates, we emulate a Skype flow, a YouTube flow and file transfers (HTTP over Internet and local server) to place our results in context. Based on our measurements we discuss approaches and potential improvements of management in effective energy usage for the tested applications.

One of the operational goals of a middleware platform is to provide a mechanism of distributing computation requests in a way that hides from the programmer the complexity of the underlying systems platform. This means that distribution mechanisms used to harness a set of computer and network resources should not expose to the programmer the detailed systems aspects which are unrelated to their application. Ideally, the programmer should be left to concentrate on the functionality of his/her application without having to be concerned with how the distribution is achieved or how the resources are used. However, this is not true today: programmers need to be aware of details of the middleware in use and are constrained by it in the design of their application, e.g. API constraints. We present a proof-of-concept demonstration of a middleware platform that imposes absolutely no constraints on the programmer apart form those used in the programming language itself. We demonstrate the efficacy of our approach with a prototype implementation in Java, running on a cluster of 20 nodes with a performance comparison with XML-RPC and Java-RMI.

New transport protocols continue to appear as alternatives to the Transmission Control Protocol (TCP). Many of these are designed to address TCP's inefficiency in operating over paths with a high bandwidth-delay product (BDP). To test these new protocols, especially comparatively, and to understand their interactions, extensions to the ns2 simulator allow real code from the linux kernel to be used within the ns2 simulations. However, how does the performance of such configurations compare to test-bed experiments of the same configuration? Although, anecdotally, there are often comments within the research community about such issues, there are no studies that quantify the differences for a specific protocol suite. Using a simple testbed, we assess four different transport protocols in a comparative study to examine how well ns2 matches reality. Our tests are all conducted at 100 Mb/s over a wide range of delay and router buffer conditions: end-to-end delays from 25 ms to 400 ms, with end-to-end path buffering of 20% to 100% of the BDP. We find that in our simple configuration, there are significant differences in performance between ns2 and the testbed.

One of the aims of cloud-based services is to offer cost savings through elastic service provision. This elasticity refers to use of resources by the customer and the provision of resources by the provider. An increasingly important resource to consider is energy (or power). As cloud services are intended to be `always on' the energy costs of cloud service provision is already significant, and will continue to rise as global energy prices continue to rise and more users make use of cloud services. While providers can invest in energy-efficient hardware, how can we make users (customers) energy-aware, and incentives users towards energy-efficient use of cloud systems? Clearly, being able to measure actual energy usage will allow the provision of suitable feedback to users, as well as enable new energy-aware systems metrics that allow systems management policies to become responsive to energy usage. We list the requirements and described a prototype for such an energy measurement system.

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.

Challenges face the Internet Architecture in order to scale to a greater number of users while providing a suite of increasingly essential functionality, such as multi-homing, traffic engineering, mobility, localised addressing and end-to-end packet-level security. Such functions have been designed and implemented mainly in isolation and retrofitted to the original Internet architecture. The resulting engineering complexity has caused some to think of 'clean slate' designs for the long-term future. Meanwhile, we take the position that an evolutionary approach is possible for a practical and scaleable interim solution, giving much of the functionality required, being backwards compatible with the currently deployed architecture, with incremental deployment capability, and which can reduce the current routing state overhead for the core network. By enhancing the way we use naming in the Internet Architecture, it is possible to provide a harmonised approach to multi-homing, traffic engineering, mobility, localised addressing and end-to-end packet-level security, including specific improvement to the scalability of inter-domain routing, and have these functions co-exist harmoniously with reduced engineering complexity. A set of proposed enhancements to the current Internet Architecture, based on naming, are described and analysed, both in terms of architectural changes and engineering practicalities.

Keeping router buffering low helps minimise delay (as well as keeping router costs low), whilst increasing buffering minimises loss. This is a trade-off for which there is no single 'correct' solution. In order to maintain effective throughput for TCP, whilst minimising router buffer requirements, current results suggest that different amounts of buffering are needed depending on the position in the network (e.g., edge or core), and on the relative capacity of ingress and egress links to a router. However, today we have several different variants of TCP in use, and each is designed to have different behaviour especially on paths with high bandwidth-delay product (BDP) values. We use a testbed to investigate the effects of different amounts of 'on-path' buffering (OPB) on the performance of four TCP variants - TCP NewReno, BIC, CUBIC, and Compound TCP - over various end-to-end round-trip-times (RTTs). Specifically, we consider how the variants respond when competing for bandwidth on a bottleneck link. We find that overall performance depends on both the RTT and the OPB provision, and that the observed behaviour is not consistent across the range of RTT and OPB values.

We present experimental results evaluating fairness of several proposals to change the TCP congestion control algorithm, in support of operation on high bandwidth-delay- product (BDP) network paths. We examine and compare the fairness of New Reno TCP BIC, cubic, hamilton-TCP, highspeed-TCP and Scalable-TCP. We focus on four different views of fairness: TCP-friendliness RTT-fairness, intra- and inter-protocol fairness.

Many new transport protocols are being defined, including, for example, variants of the Transmission Control Protocol (TCP), to better match the requirements of new applications. A key issue in the evaluation of protocol flows, in terms of their performance, is how fair they are to other flows. Specifically, it is important to understand how a mix of existing and/or new protocols will interact with each other when using the same network resources. Such observations help to inform protocol design, and allow an assessment of potential impacts on users. We present a simple, yet effective, methodology for examining a specific case of inter-flow fairness based solely on measurements of flow performance. As well as using an existing fairness metric, we propose a new metric which provides a richer information summary for the evaluation of fairness.

Rapid and unpredictable topology changes and resource constraints make delivering packets in a MANET (Mobile Ad hoc Network) a challenging task. Routing information has to be updated to reflect the topology changes and maintain the correctness of route selection. On the other hand, the dissemination of control messages has to be optimised for efficient resource usage and to alleviate channel contention problems. To solve this problem, this dissertation focuses on how to automatically tune routing performance for MANETs in terms of packet delivery ratio and control overhead. The impacts of soft state signalling, especially the refresh intervals, are studied under various scenarios. A variety of topology advertisement strategies are presented. Two self-tuning neighbour detection schemes are proposed, the Dynamic Timer algorithm and the Fast Neighbour Handshake algorithm, in order to enhance routing performance.

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.

We describe a method for enabling dependable forwarding of messages in untrusted networks. Nodes perform only relatively lightweight operations per message, and only the originator and destination need to trust each other. Whereas existing protocols for dependable communication rely on establishing a verifiable identity for every node, our protocol can operate in networks with unknown or varying membership and with no limits on the creation of new identities. Our protocol supports the maintenance of unlinkability: relays cannot tell whether a given originator and destination are communicating. The destination of each message generates an unforgeable acknowledgement (U-ACK) that allows relays and the originator to verify that the message was delivered unmodified to the destination, but relays do not need to share keys with the originator or destination, or to know their identities. Similarly, the endpoints do not need to know the identities of the relays. U-ACKs can be seen as a building block for dependable communication systems; they enable nodes to measure the level of service provided by their neighbours and optionally to adjust the level of service they provide in return, creating an incentive for nodes to forward messages. Our work is ongoing.

This paper presents a fast neighbour detection scheme for a proactive MANET routing protocol. Instead of using periodic HELLO messages, the proposed scheme adopts explicit handshake mechanism to reduce the latency in neighbour detection. In particular, two route handshake options are presented, namely the Broadcast based handshake (BHS) algorithm and Unicast based handshake (UHS) algorithm. Our simulation results show that the proposed scheme improves routing performance, especially in networks with moderate or high mobility. In low-density networks, the unicast option improves the routing throughput significantly without introducing extra control overhead.

In wireless mission-critical systems, systems may be resource-constrained including limited bandwidth, so minimising protocol overhead, whilst maintaining performance, is important. Proactive MANET routing protocols tend to provide smaller route discovery latency than on-demand protocols because they maintain route information to all the nodes in the network at all time. However, such protocols may impose excessive soft-state routing control overhead which is generated by disseminating periodic update messages. In order to mitigate the side effects of the soft-state control over-heads, we propose two adaptive proactive routing algorithms, namely DT_MIAD and DT_ODPU. By tuning the value of refresh intervals dynamically and automatically, refresh updates are triggered based on traffic conditions and node mobility. We show through simulations that the proposed adaptive routing algorithms can outperform a traditional proactive routing protocol (OLSR).

Optimised link state routing (OLSR) is a popular protocol for use in MANET networks. In this paper, we investigate the different impacts of tuning refresh interval timers on OLSR performance under various scenarios (varying node density and node speed). Based on the simulation results with NS2, we find that although reducing refresh intervals could improve OLSR's performance, the intervals for some message types (HELLO messages) have a bigger impact on OLSR performance than for other message types. We find that the impact of the interval timer grows with increased network mobility and node density

Mobile devices available today provide users the ability to communicate using a number of different wireless network interfaces. However, these devices do not yet fully exploit the potential for multi-homed and multi-path communication allowing them to better utilise all the connectivity that is available to them. We present here the coalition peering domain (CPD), an architecture that supports collaborative networking relationships between mobile devices. This improves the speed and robustness of communication through more flexible use of all available connectivity

In the near future, billing for network services will not only be concerned with time or volume based accounting but also in ways of measuring the quality of the service provided. Dynamic price schemes, such as congestion-based charging, have been proposed. In some of these models, the charging infrastructure relies on the distribution of electronic tariffs to end-users machines. The tariff structure includes the price information and an algorithm to calculate the charge. Thus, the monitoring of network usage according to this tariff is essential within these frameworks. However, little attention has been given to the security issues associated with Internet metering in these schemes. This has had a great impact on the new models proposed today, since security has become a major concern in open networks. Systems that naturally have incentive to fraud, such as metering systems used for billing purposes, must deal with security threats in large scale environments. The article compiles the security issues of a dynamic networked system where electronic tariffs and service level agreement (SLA) structures are distributed among service providers and customers. To address these issues, a set of security protocols is outlined.

In this paper we attempt to gain an understanding of the behaviour of users in a multipoint, interactive communication scenario. In particular, we wish to understand the dynamics of user participation at a session level. We present wide-area session level traces of the popular multiplayer networked games Quake and Half-Life. These traces were gathered by regularly polling 2256 game servers located all over the Internet, and querying the number of players present at each server and how long they had been playing. We analyse three specific features of the data: the number of players in a game, the interarrival times between players and the length of a player's session. We find significant time-of-day and network externality effects in the number of players. Player duration times fit an exponential distribution, while interarrival times fit a heavy-tailed distribution. The implications of our findings are discussed in the context of provisioning and charging for network quality of service for multipoint and multicast transmission. This work is ongoing.