PCN based admission control for autonomic video quality differentiation: design and evaluation

The popularity of multimedia services has introduced important new challenges for broadband access network management. As these services are very prone to network anomalies such as packet loss and jitter, accurate admission control mechanisms are needed to avoid congestion. Traditionally, centralized admission control mechanisms often underperform in combination with multimedia services, as they fail to effectively characterize the amount of needed resources. Recently, measurement based admission control mechanisms have been proposed such as the IETF Pre-Congestion Notification (PCN) mechanism, where the network load is measured at each intermediate node and signaled to the edge, where the admittance decision takes place. In this article, we design a PCN based admission control mechanism, optimized for protecting bursty traffic such as video services, which is currently not studied in the PCN working group. We evaluated and identified the effect of PCN's configuration in protecting bursty traffic. The proposed admission control mechanism features three main improvements to the original PCN mechanism: first, it uses a new measurement algorithm, which is easier to configure for bursty traffic. Second, it allows to automatically adapt PCN's configuration based on the traffic characteristics of the current sessions. Third, it introduces the differentiation between video quality levels to achieve an admission decision per video quality level of each request. The mechanism has been extensively evaluated in a packet switched simulation environment, which shows that the novel admission control mechanism is able to protec

Service oriented networking for multimedia applications in broadband wireless networks

Extensive efforts have been focused on deploying broadband wireless networks. Providing mobile users with high speed network connectivity will let them run various multimedia applications on their wireless devices. In order to successfully deploy and operate broadband wireless networks, it is crucial to design efficient methods for supporting various services and applications in broadband wireless networks. Moreover, the existing access-oriented networking solutions are not able to fully address all the issues of supporting various applications with different quality of service requirements. Thus, service-oriented networking has been recently proposed and has gained much attention. This dissertation discusses the challenges and possible solutions for supporting multimedia applications in broadband wireless networks. The service requirements of different multimedia applications such as video streaming and Voice over IP (VoIP) are studied and some novel service-oriented networking solutions for supporting these applications in broadband wireless networks are proposed. The performance of these solutions is examined in WiMAX networks which are the promising technology for broadband wireless access in the near future. WiMAX networks are based on the IEEE 802.16 standards which have defined different Quality of Service (QoS) classes to support a broad range of applications with varying service requirements to mobile and stationary users. The growth of multimedia traffic that requires special quality of service from the network will impose new constraints on network designers who should wisely allocate the limited resources to users based on their required quality of service. An efficient resource management and network design depends upon gaining accurate information about the traffic profile of user applications. In this dissertation, the access level traffic profile of VoIP applications are studied first, and then a realistic distribution model for VoIP traffic is proposed. Based on this model, an algorithm to allocate resources for VoIP applications in WiMAX networks is investigated. Later, the challenges and possible solutions for transmitting MPEG video streams in wireless networks are discussed. The MPEG traffic model adopted by the WiMAX Forum is introduced and different application-oriented solutions for enhancing the performance of wireless networks with respect to MPEG video streaming applications are explained. An analytical framework to verify the performance of the proposed solutions is discoursed, and it is shown that the proposed solutions will improve the efficiency of VoIP applications and the quality of streaming applications over wireless networks. Finally, conclusions are drawn and future works are discussed

Quality of Service Support in IEEE 802.11 Wireless LAN

Wireless Local Area Networks (WLANs) are gaining popularity at an unprecedented rate, at home, at work, and in public hot spot locations. As these networks become ubiquitous and an integral part of the infrastructure, they will be increasingly used for multi-media applications. The heart of the current 802.11 WLANs mechanism is the Distributed Coordination Function (DCF) which does not have any Quality of Service (QoS) support. The emergence of multimedia applications, such as the local services in WLANs hotspots and distributions of entertainment in residential WLANs, has prompted research in QoS support for WLANs. The absence of QoS support results in applications with drastically different requirements receiving the same (yet potentially unsatisfactory) service. Without absolute throughput support, the performance of applications with stringent throughput requirements will not be met. Without relative throughput support, heterogeneous types of applications will be treated unfairly and their performance will be poor. Without delay constraint support, time-sensitive applications will not even be possible. The objective of this dissertation is, therefore, to develop a comprehensive and integrated solution to provide effective and efficient QoS support in WLANs in a distributed, fair, scalable, and robust manner.In this dissertation, we present a novel distributed QoS mechanism called Distributed Relative/Absolute Fair Throughput with Delay Support (DRAFT+D). DRAFT+D is de- signed specifically to provide integrated QoS support in IEEE 802.11 WLANs. Unlike any other distributed QoS mechanism, DRAFT+D supports two QoS metrics (throughput and delay) with two QoS models (absolute and relative) under two fairness constraints (utilitarian and temporal fairness) in the same mechanism at the same time a fully distributed manner. DRAFT+D is also equipped with safeguards against excessive traffic injection DRAFT+D operates as a fair-queuing mechanism that controls packet transmissions (a) by using a distributed deficit round robin mechanism and (b) by modifying the way Backoff Interval (BI) are calculated for packets of different traffic classes. Fair relative throughput support is achieved by calculating BI based on the throughput requirements. Absolute throughput and delay support are achieved by allocating sufficient shares of bandwidth to these types of traffic