George Kamel

An Information-Centric Communication Infrastructure for Real-Time State Estimation of Active Distribution Networks

The evolution toward emerging active distribution networks (ADNs) can be realized via a real-time state estimation (RTSE) application facilitated by the use of phasor measurement units (PMUs). A critical challenge in deploying PMU-based RTSE applications at large scale is the lack of a scalable and flexible communication infrastructure for the timely (i.e., sub-second) delivery of the high volume of synchronized and continuous synchrophasor measurements. We address this challenge by introducing a communication platform called C-DAX based on the information-centric networking (ICN) concept. With a topic-based publish-subscribe engine that decouples data producers and consumers in time and space, C-DAX enables efficient synchrophasor measurement delivery, as well as flexible and scalable (re)configuration of PMU data communication for seamless full observability of power conditions in complex and dynamic scenarios. Based on the derived set of requirements for supporting PMU-based RTSE in ADNs, we design the ICN-based C-DAX communication platform, together with a joint optimized physical network resource provisioning strategy, in order to enable the agile PMU data communications in near real-time. In this paper, C-DAX is validated via a field trial implementation deployed over a sample feeder in a real-distribution network; it is also evaluated through simulation-based experiments using a large set of real medium voltage grid topologies currently operating live in The Netherlands. This is the first work that applies emerging communication paradigms, such as ICN, to smart grids while maintaining the required hard real-time data delivery as demonstrated through field trials at national scale. As such, it aims to become a blueprint for the application of ICN-based general purpose communication platforms to ADNs.

A publish/subscribe communication framework for managing electric vehicle charging

Electric Vehicle (EV) based applications have recently received wide interests from both commercial and research communities, thanks to the avoidance of CO2 pollution by using electric energy instead of traditional fuel energy. With the deployment of public Charging Stations (CSs), the travelling distance of EVs could be substantially increased by recharging their electric energy during journeys. Different from the existing research on decision making to improve charging performance, in this paper we focus on how necessary dynamic information in relation to the charging service can be efficiently disseminated to on-the-move EVs which potentially require charging at CSs. We propose an efficient communication framework based on Publish/Subscribe (P/S) mechanism to disseminate necessary information of CSs to EVs. Those EVs subscribing to such information could then make their individual decisions to select a desired CS for charging, according to received information such as expected waiting time. A core part of communication framework is the utilization of Road Side Units (RSUs) to bridge the information flow from CSs to EVs, which has been regarded as a type of cost-efficient communication infrastructure. In this context, we introduce two complementary communication modes, namely Push and Pull Modes, in order to enable the required information dissemination operation. Both options are evaluated based on realistic simulation models, in particular on how information freshness can influence the overall charging performance based on a common CS selection strategy.

CAINE: a context-aware information-centric network ecosystem

Information-centric networking (ICN) is an emerging networking paradigm that places content identifiers rather than host identifiers at the core of the mechanisms and protocols used to deliver content to end users. Such a paradigm allows routers enhanced with content-awareness to play a direct role in the routing and resolution of content requests from users, without any knowledge of the specific locations of hosted content. However, to facilitate good network traffic engineering and satisfactory user QoS, content routers need to exchange advanced network knowledge to assist them with their resolution decisions. In order to maintain the location-independency tenet of ICNs, such knowledge (known as context information) needs to be independent of the locations of servers. To this end, we propose CAINE - Context-Aware Information-centric Network Ecosystem - which enables context-based operations to be intrinsically supported by the underlying ICN routing and resolution functions. Our approach has been designed to maintain the location-independence philosophy of ICNs by associating context information directly to content rather than to the physical entities such as servers and network elements in the content ecosystem, while ensuring scalability. Through simulation, we show that based on such location-independent context information, CAINE is able to facilitate traffic engineering in the network, while not posing a significant control signalling burden on the network.

Enabling resilient smart grid communication over the information-centric C-DAX middleware

Limited scalability, reliability, and security of todays utility communication infrastructures are main obstacles to the deployment of smart grid applications. The C-DAX project aims at providing and investigating a communication middleware for smart grids to address these problems, applying the information-centric networking and publish/subscribe paradigm. We briefly describe the C-DAX architecture, and extend it with a flexible resilience concept, based on resilient data forwarding and data redundancy. Different levels of resilience support are defined, and their underlying mechanisms are described. Experiments show fast and reliable performance of the resilience mechanism.

A Cost-Optimal QoS Aggregation Policy for Network Mobility: Analysis and Performance Comparisons

The potentially large population density and high handover rates of mobile users aboard a public transport vehicle underpin the need for robust and scalable quality-of-service (QoS) provisioning mechanisms designed for such environments. Traditional QoS approaches fall short of such criteria and have led to the proposal of a number of aggregation-based QoS mechanisms that maintain a single QoS state in the access network for the entire moving network subnet. Although such proposals can increase handover scalability, the dynamic connectivity and population of users within public transport vehicles can lead to bursts of requests being made due to passengers embarking on a vehicle in groups, intermittently increasing the control signaling density in the network and consequently increasing the cost to the operator. QoS aggregation policies alleviate this problem by buffering QoS requests at the mobile router installed on the vehicle for a period of time and then aggregating these into a single request to alter the resources reserved in the access network for the moving network. A number of such policies have previously been proposed in the literature to control and manage the buffering duration at the mobile router. However, since the aggregation decision of these policies is based on a static request-rate-dependent parameter, cost inefficiency can occur when the request rate is variable, as is typical of public transport vehicles due to passengers embarking and disembarking. This paper therefore provides a full mathematical and simulation-based analysis of a novel cost-driven aggregation policy and compares its performance with that of other policies previously proposed in the literature. Our results show that our cost-driven policy can reduce operator costs due to signaling by up to 21% compared with other policies while, at the same time, not putting the user at a disadvantage with long and unpredictable waiting times to establish a session.

Case analysis of a Cost-Optimal QoS aggregation policy for network mobility

The network mobility reservation protocol was proposed to increase the scalability of QoS provision in moving networks. However, its scalability is undermined when sessions are bursty and short-lived. QoS aggregation addresses this by holding requests at the mobile router for a time before sending a single aggregated reservation to the access network. This letter analyses a cost-optimal QoS aggregation policy under the case of bursty requests, and compares its expected cost efficiency and user waiting time with that of other previously proposed policies. It is shown that the C-policy reduces operator costs compared to other policies, whilst also reducing expected queueing times.

Cost-Optimal QoS Aggregation for Network Mobility

Many existing communication protocols fail to perform efficiently when groups of users move in unison and at high velocity. A classic example is the Mobile IP protocol, which, as it stands, leads to storms of binding updates at every IP handover, but is resolved by the NEMO basic support protocol. However, a problem of similar nature is also existent in Quality of Service protocols, which again tend to produce signalling storms at handover, leading to, somewhat paradoxically, surges of congestion within the access network. While QoS aggregation improves protocol scalability by maintaining a single QoS state for potentially the entire moving network rather than for each individual node, the act of having to constantly maintain this state when sessions are frequently created and terminated undermines its benefit. We therefore propose a dynamic cost-driven QoS aggregation policy, which aims at minimising network operator costs for each aggregation cycle. Simulations of the cost-driven policy show that costs are reduced by up to 6.5% relative to other QoS aggregation policies, with expected user waiting times prior to session establishment increasing by a only a fraction of a second.

A combined mobility and QoS framework for delivering ubiquitous services

From a network perspective, the major challenge in providing seamless connectivity whilst maintaining the required level of QoS to users results from the negative interactions that occur between mobility and QoS. These interactions, particularly those of mobility and QoS, have been the subject of much research. In this paper, we discuss the various approaches that have already been taken to combine QoS and mobility mechanisms, and present a new framework to combine such mechanisms with the aim of reducing the negative interactions that might arise between them. We propose the concept of enhanced nodes which is a special IP router with an extra sub-layer of mobility, QoS and security features. Our framework is illustrated with an example of a QoS-based mobility selection mechanism.

A seamless QoS-enabled mobility management mechanism for moving networks

The demand for resource-hungry applications whilst on the move is growing, and is being fuelled in particular by the increasing availability of high-quality multimedia services. To this end, micro-mobility protocols play an important role in providing seamless data delivery to terminals as they roam across different networks. However, such protocols typically lead to bottleneck congestion occurring within the access network. Within moving networks, in which a potentially vast number of terminals are present, the bottleneck congestion problem is significantly magnified, and can lead to increased call dropping probability and/or quality-of-service degradation. This paper therefore presents a novel mechanism, designed to ensure that the continuity of all sessions of a moving network is seamlessly preserved as it performs handovers to and within micro-mobility-enabled access networks.