Performance evaluation of information and communications technology infrastructure for smart distribution network applications

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.Current electrical networks require secure, scalable and cost-effective Information and Communications Technology (ICT) solutions to facilitate the novel functionalities required by Smart Grids. Countries around the globe are investigating alternative energy sources to mitigate the current energy crisis and environmental issues experienced by many countries due to global warming, rapid growth of population, inefficient energy management, dwindling fossil fuel resources, etc. Therefore, alternative or renewable energy sources, such as wind, solar, hydro, combined heat and power, etc., are required to mitigate such a crisis and such sources will also need to be integrated in to the power grid in a distributed manner. Such distributed energy sources are mainly connected to the distribution networks and introduce huge challenges to the distribution network operator (DNO). Many of these challenges cannot be dealt with effectively using existing network operation mechanisms therefore the research and development of novel ICT solutions to support smart distribution network operation is required. This research investigated suitable ICT solutions to enable the Smart Grid to tackle these challenges and proposes ICT infrastructure models that can be used for simulation studies in order to investigate cost-effective, scalable and secure solutions for the DNOs. Initially, a Quality of Service (QoS) monitoring test-bed was proposed to evaluate the performance of bandwidth intensive applications, such as smart meter data transmission. Simulation studies for different communication technologies, cellular and Power Line Communication (PLC), were also carried out and the simulation models were verified using experimental test results. Finally, the modelling and analysis of smart metering infrastructure was carried out using simulation and extensive studies were performed to evaluate the data transmission rate performance for different configurations of smart meters and concentrators

Web browsing optimization over 2.5G and 3G: end-to-end mechanisms vs. usage of performance enhancing proxies

Published version on Wiley's platform: https://onlinelibrary.wiley.com/doi/abs/10.1002/wcm.4562.5 Generation (2.5G) and Third Generation (3G) cellular wireless networks allow mobile Internet access withbearers specifically designed for data communications. However, Internet protocols under-utilize wireless widearea network (WWAN) link resources, mainly due to large round trip times (RTTs) and request–reply protocolpatterns. Web browsing is a popular service that suffers significant performance degradation over 2.5G and 3G. Inthis paper, we review and compare the two main approaches for improving web browsing performance over wirelesslinks: (i) using adequate end-to-end parameters and mechanisms and (ii) interposing a performance enhancingproxy (PEP) between the wireless and wired parts. We conclude that PEPs are currently the only feasible way forsignificantly optimizing web browsing behavior over 2.5G and 3G. In addition, we evaluate the two main currentcommercial PEPs over live general packet radio service (GPRS) and universal mobile telecommunications system(UMTS) networks. The results show that PEPs can lead to near-ideal web browsing performance in certain scenarios.Postprint (published version

Network-wide Measurement of TCP RTT in 2G Networks

We analyze existing server-side log data of a large scale automatic toll system to measure the TCP round-trip-time (RTT) as experienced by the communication between the central system and the on-board units (OBUs) deployed for tolling heavy-goods vehicles. The RTT is estimated from passive monitoring by parsing server-side log files and aggregating fleet-wide statistics over time. Using this data we compare the characteristics of the four different types of OBU and the three GPRS (2G) networks used. We find the RTT data to be consistent with existing, smaller samples and extend the observed RTT range by an order of magnitude. The OBU types exhibit a markedly different behavior, most notably for long RTTs, and we find one of the 2G networks to -˜hum’ at 50 Hz and harmonics

Myspeedtest: active and passive measurements of cellular data networks

As the number and diversity of applications available to mobile users increases, there is an increasing need for developers, network service providers, and users to understand how users perceive the network performance of these applications. MySpeedTest is a measurement tool that actively probes the network to determine not only TCP throughput and round trip time, but also the proximity to popular content providers, IP packet delay variation, and loss. It also records other metadata that could affect user experience, such as signal strength, service provider, connection type, battery state, device type, manufacturer, time of day, and location. The tool also takes passive measurements of the applications installed on the device and the network usage of these applications. My SpeedTest is available on the Google Play Store and currently has 1300+ active users. This thesis presents the design and implementation of MySpeedTest as well as effect of metrics like latency and IP packet delay variation on performance.MSCommittee Chair: Nick Feamster; Committee Member: Patrick Traynor; Committee Member: Raghupathy Sivakuma

An investigation into dynamic TLPs for smartphone communication: To facilitate timed response in way finding for vision impaired people

A reliable, high speed and efficient data transfer method is a very important factor in real time Way-finding systems since it requires information with very low latency to discover paths, avoid dangerous situations, identified changes in existing maps and alternative routes. This research will develop models and methods to facilitate bounded timing with minimal latency for way-finding application for vision impaired people. As a result of analyzing the requirements for Way-finding applications, it was noted that some typical behaviours involve relatively small amount of data transfer through networks. Existing Transport Layer Protocols (TLP) are not ideal for providing such requirements. This research investigates existing TLPs and proposes modifications / extensions to facilitate demands in Way-finding applications and will implement the Dynamic TLP to incorporate both reliable data transfers with high efficiency as well as frequent data transfers which do not require reliability

Security for constrained IoT devices

Tese de mestrado, Segurança Informática, Universidade de Lisboa, Faculdade de Ciências, 2020In the recent past the Internet of Things has been the target of a great evolution, both in terms of applicability and of use. Society increasingly wants to use and massify the IoT to obtain information and act in the environment, for example, to remotely control an irrigation system. The reduction in the cost of devices and the constant evolution of personal mobile devices has largely contributed to their spread. However, its implementation is carried out in adverse environments and outside the typical information systems. The devices are, as a rule, limited in terms of resources, both computation and memory. The applicability to the IoT of the security techniques already known to conventional systems has therefore to be adapted, because it does not take into account the characteristics of the resources of the devices and require additional load when exchanging messages between these system elements. In addition, the development of applications is difficult because there is not yet developed tools and standards as there are for the traditional HTTPS or TLS when considering conventional systems. In this work, we intend to present a prototype of a low-cost solution (compared to existing equivalent solutions) that uses a secure communication channel based on standard protocols. An application is also developed based on technologies more familiar to programmers, similar to traditional Web development. We took into account the ”Green By Web” project as a case study. We have concluded that it is possible to have a secure communication, using UDP/DTLS over the CoAP protocol. With this approach we optimized the number of exchanged messages between the client and the server to be up to 8 times less and their size to be up to 10%, comparing against applications that use TCP/TLS connections, such as web applications that use HTTPS. This allows the energy spent by the low-cost components to be lower and increases their battery lifetime