Cristian Olariu

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-Ts 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.

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.

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.

Integration of QoS Metrics, Rules and Semantic Uplift for Advanced IPTV Monitoring

Abstract 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.

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.

Real-time monitoring of SDN networks using non-invasive cloud-based logging platforms

The Software Defined Networking (SDN) paradigm enables quick deployment of software controlled network infrastructures, however new approaches to system monitoring are required to provide network administrators with instant feedback on a networks health. This paper details the deployment of an SDN system architecture featuring the integration of a cloud-based, real-time log-analysis platform. The proposed architecture uses log data collected from host machines, OpenFlow switches and the SDN controllers in a non-invasive style. This work uses a commercially available correlation platform to provide network administrators with a real-time view of the network status and the approach is validated under two scenarios: — network overload and a security attack.

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 networks VoIP call capacity, and this is validated through NS-3 simulations.

Adaptive multicast streaming for videoconferences on software-defined networks

Abstract Real-time applications, such as video conferences, have strong Quality of Service requirements for ensuring a decent Quality of Experience. Nowadays, most of these conferences are performed over wireless devices. Thus, an appropriate management of both heterogeneous mobile devices and network dynamics is necessary. Software Defined Networking enables the use of multicasting and stream layering inside the network nodes, two techniques able to enhance the quality of live video streams. In this paper, we propose two algorithms for building and maintaining multicast sessions in a software-defined network. The first algorithm sets up the initial multicast trees for a given call. It optimally places the stream layer adaptation function inside the core network in order to minimize the bandwidth consumption. This algorithm has two versions: the first one, based on shortest path trees is minimizing the latency, while the second one, based on spanning trees is minimizing the bandwidth consumption. The second algorithm adapts the multicast trees according to the network changes occurring during a call. It does not recompute the trees, but only relocates the stream layer adaptation functions. It requires very low computation at the controller, thus making our proposal fast and highly reactive. Extensive simulation results confirm the efficiency of our solution in terms of processing time and bandwidth savings compared to existing solutions such as multiple unicast connections, Multipoint Control Unit solutions and application layer multicast.

OpenFlow based VoIP QoE monitoring in enterprise SDN

The global view enabled by a Software Defined Network (SDN) architecture allows us to observe the contribution of each congested router to the overall Mean Opinion Score (MOS) degradation of a VoIP service. Thus, when a number of routers in the path may add to the MOS degradation, the SDN controller can quantify the contribution from each router. This work presents the implementation of a network monitoring system for OpenFlow protocol aware enterprise VoIP networks. The presented solution enables network administrators and developers to access on demand information about intermediate packet loss and MOS for real-time applications. The main contribution of this work is an out-of-the-box architecture to enable users to find the exact location of quality degradation with a small operational cost.

Delay-based priority queueing for VoIP over Software Defined Networks

Software Defined Networking and Network Function Virtualisation provide significantly more flexibility and control when provisioning QoS for delay sensitive services. Network delay can have a detrimental impact on VoIP quality and, therefore, minimising delay can help maintain the quality and prevent call dropping. This paper proposes a queuing scheme based on packet delay for prioritising VoIP calls made over SDN. An OpenFlow testbed was developed to validate our proposal, and results show that delay-based prioritisation of VoIP packets in SDN networks ensures that only a small number of users will be affected by network congestion.