Now showing 1 - 10 of 10
  • Publication
    DAPP: A Delay-Aware Packet Prioritisation Scheme for VoIP in Wireless Multi-hop Networks
    (IEEE, 2016-07-13) ;
    In this paper we propose a mechanism entitled Delay-Aware Packet Prioritisation (DAPP) that works at WiFi packet queue level. DAPP enqueues packets according to their time spent in the network, such that more delayed packets are enqueued towards the head of the queue. We study the effects of such an approach in wireless multi-hop scenarios where VoIP packets with various delay impairments reach a congested node. Packets’ delay builds up as congestion increases and we show that DAPP improves a network’s VoIP capacity by distributing the negative effects of delay to those VoIP packets that so far travelled in good network conditions. This is to the advantage of those VoIP packets already negatively affected by network conditions, as they are allowed to pass a congested node with less further delay accumulation. We use extensive NS-3 simulations where a wide range of network impairments affect VoIP calls, and we demonstrate that DAPP is able to improve the VoIP capacity and fairness among VoIP calls in a wireless multi-hop network.
  • Publication
    Experience of developing an openflow SDN prototype for managing IPTV networks
    IPTV is a method of delivering TV content to endusers that is growing in popularity. The implications of poor video quality may ultimately be a loss of revenue for the provider. Hence, it is vital to provide service assurance in these networks. This paper describes our experience of building an IPTV Software Defined Network testbed that can be used to develop and validate new approaches for service assurance in IPTV networks. The testbed is modular and many of the concepts detailed in this tutorial may be applied to the management of other end-to-end services.
      1469Scopus© Citations 9
  • Publication
    Impact of non-deterministic software execution times in SmartGrid applications
    Electricity companies will only allow customers to inject power into the grid network if the customer’s system is in synch with both frequency and phase as the grid itself. This is normally achieved using a specialised machine sold by the energy provider. It may be possible to achieve this via low cost, low power nodes such as a Raspberry Pi, to synchronize frequency and phase as well as voltage and current. In order to synchronize to microsecond or nanosecond precision, the hardware being deployed must in itself be able to achieve said precision when coupled with software. In this paper we evaluate the level of nondeterministic execution times in two versions of a widespread embedded compute platform, namely Raspberry Pi.
      338Scopus© Citations 1
  • Publication
    Prototyping telematic services in a wireless vehicular mesh network environment
    Next generation telematic services are expected to play a key role in future automotive applications. In order to achieve strong integration between the services and the underlying network infrastructure there is a need for both simulation and emulation of the entire system. This paper presents a combined simulation and emulation approach for telematic services prototyping in an emulated wireless vehicular mesh networking environment. The ns-3 wireless mesh model, SUMO vehicular mobility model and different telematic services are integrated to demonstrate high scalability and flexibility of the proposed approach.
      482Scopus© Citations 4
  • Publication
    VoIP Quality Monitoring in LTE Femtocells
    The increasing number of users demanding voice and data communication through cellular networks has driven the need for higher network throughput rates and lower latency. LTE femtocells address this pressing problem by offloading cellular service providers networks and increase both coverage and capacity for their users. Assuming a wired DSL backhaul for these femtocells, this paper shows simulations exploring a case where the DSLAM represents the main bottleneck when the cellular network operator and the DSL provider do not collaborate. This paper introduces the concept of Intermediary Mean Opinion Score which may be employed at femtocell gateways to isolate network problems and feed into customer experience management. We also propose and investigate a technique of mapping the human audio recency into the MOS calculation. Results are presented to illustrate the information that can be extracted from a lightweight monitor in the network.
      471Scopus© Citations 12
  • Publication
    A Delay-aware Packet Prioritisation Mechanism for Voice over IP in Wireless Mesh Networks
    This work proposes a novel Delay-aware Packet Prioritisation Mechanism (DPPM) to uniformly distribute the Quality of Service (QoS) level across all Voice Over IP (VoIP) calls in a Wireless Mesh Network (WMN). The method prioritises VoIP packets based on the amount of queueing delay that has been accumulated across multiple hops within the WMN. The accumulated queueing delay is piggybacked over every VoIP packet and is used at the enqueueing phase to place more delayed packets towards the head of the queue. This assures higher priority for more delayed VoIP packets over less delayed VoIP packets. The influence of the queueing delay on voice call quality is further reduced by utilising the proposed DPPM in conjunction with WiFi frame aggregation. This conjunction increases the network's VoIP call capacity, and this is validated through NS-3 simulations.
      470Scopus© Citations 14
  • Publication
    Integration of QoS Metrics, Rules and Semantic Uplift for Advanced IPTV Monitoring
    Increasing and variable traffic demands due to triple play services pose significant Internet Protocol Television (IPTV) resource management challenges for service providers. Managing subscriber expectations via consolidated IPTV quality reporting will play a crucial role in guaranteeing return-on-investment for players in the increasingly competitive IPTV delivery ecosystem. We propose a fault diagnosis and problem isolation solution that addresses the IPTV monitoring challenge and recommends problem-specific remedial action. IPTV delivery-specific metrics are collected at various points in the delivery topology, the residential gateway and the Digital Subscriber Line Access Multiplexer through to the video Head-End. They are then pre-processed using new metric rules. A semantic uplift engine takes these raw metric logs; it then transforms them into World Wide Web Consortium’s standard Resource Description Framework for knowledge representation and annotates them with expert knowledge from the IPTV domain. This system is then integrated with a monitoring visualization framework that displays monitoring events, alarms, and recommends solutions. A suite of IPTV fault scenarios is presented and used to evaluate the feasibility of the solution. We demonstrate that professional service providers can provide timely reports on the quality of IPTV service delivery using this system.
      2468Scopus© Citations 8
  • Publication
    A QoS based call admission control and resource allocation mechanism for LTE femtocell deployment
    Current trends show a growing number of femtocell deployments, this in turn will lead to increased volumes of voice traffic being transmitted through fixed broadband access networks such as Digital Subscriber Line. In this paper the issue of maintaining call quality through the resource constraint expedited forwarding queue of DSLAMs is investigated. A quality based Call Admission Control and resource allocation mechanism is provided to avoid resource overloading and call quality degradation. The ITU-T's E-Model is used for call quality monitoring and a message exchange interface between the mobile and fixed networks which allows dynamic adjustment to network resources is described and simulated. The results show that high voice call quality can be maintained.
      447Scopus© Citations 22
  • Publication
    Provisioning call quality and capacity for femtocells over wireless mesh backhaul
    The primary contribution of this paper is the design of a novel architecture and mechanisms to enable voice services to be deployed over femtocells backhauled using a wireless mesh network. The architecture combines three mechanisms designed to improve Voice Over IP (VoIP) call quality and capacity in a deployment comprised of meshed femtocells backhauled over a WiFi-based Wireless Mesh Network (WMN), or femto-over-mesh. The three mechanisms are: (i) a Call Admission Control (CAC) mechanism employed to protect the network against congestion; (ii) the frame aggregation feature of the 802.11e protocol which allows multiple smaller frames to be aggregated into a single larger frame; and (iii) a novel delay-piggy-backing mechanism with two key benefits: prioritizing delayed packets over less delayed packets, and enabling the measurement of voice call quality at intermediate network nodes rather than just at the path end-points. The results show that the combination of the three mechanisms improves the system capacity for high quality voice calls while preventing the network from accepting calls which would result in call quality degradation across all calls, and while maximizing the call capacity available with a given set of network resources.
      379Scopus© Citations 5
  • Publication
    Enabling IPTV service assurance using OpenFlow
    One difficulty facing Internet Protocol Television (IPTV) service providers is the issue of monitoring and managing their service delivery network. An in-depth monitoring regime is required, which performs measurements within different networking devices. When network conditions deteriorate to the point where they could disrupt IPTV services, Network Operators (NOs) can use the measurements as a basis to reconfigure the network with minimal delay. OpenFlow (OF) presents a potential solution to this problem as it provides vendor-neutral access to the packet forwarding interface of the different hardware device types. This work investigates how OF can leverage video packet inspection measurements taken from within the IPTV service delivery network and combine these with of statistics to make decisions regarding routing in order to assure service quality.
      667Scopus© Citations 14