Development of a Quality of Service Framework for Multimedia Streaming Applications

By the year 2012, it is expected that the majority of all Internet traffic will be video content. Coupled with this is the increasing availability of Wireless Local Area Networks (WLANs) due to their ease of deployment, flexibility and reducing roll out costs. Unfortunately the contention based access mechanism utilised by IEEE 802.11 WLANs does not suit the non-uniform or bursty bandwidth profile of a video stream which can lead to a reduced quality of service (QoS) being experienced by the end-user. In 2005, the IEEE 802.11e protocol was ratified in an attempt to solve this emerging problem. It provides for an access prioritization mechanism based upon four separate traffic classes or access categories (ACs). Each AC is characterised by a set of access parameters that determine its level of access priority which is turn determines the amount of bandwidth available to it. Computer simulation studies have shown that AC prioritisation can yield significant improvements in the QoS delivered over a WLAN. However, these studies have been based upon the use of static access parameters for the ACs. In practice, this is not a viable solution owing to the dynamic and unpredictable nature of the operating conditions on WLANs. In this thesis, an experimental study of AC prioritisation based upon adaptive tuning of the access parameters is presented. This new approach to bandwidth provisioning for video streaming is shown to yield significant improvements in the QoS under a wide range of different operating conditions. For example, it is shown that by adaptively tuning the access control parameters in response to the network conditions, the number of video frames delivered that satisfy QoS requirements is more than doubled

Quality of service differentiation for multimedia delivery in wireless LANs

Delivering multimedia content to heterogeneous devices over a variable networking environment while maintaining high quality levels involves many technical challenges. The research reported in this thesis presents a solution for Quality of Service (QoS)-based service differentiation when delivering multimedia content over the wireless LANs. This thesis has three major contributions outlined below: 1. A Model-based Bandwidth Estimation algorithm (MBE), which estimates the available bandwidth based on novel TCP and UDP throughput models over IEEE 802.11 WLANs. MBE has been modelled, implemented, and tested through simulations and real life testing. In comparison with other bandwidth estimation techniques, MBE shows better performance in terms of error rate, overhead, and loss. 2. An intelligent Prioritized Adaptive Scheme (iPAS), which provides QoS service differentiation for multimedia delivery in wireless networks. iPAS assigns dynamic priorities to various streams and determines their bandwidth share by employing a probabilistic approach-which makes use of stereotypes. The total bandwidth to be allocated is estimated using MBE. The priority level of individual stream is variable and dependent on stream-related characteristics and delivery QoS parameters. iPAS can be deployed seamlessly over the original IEEE 802.11 protocols and can be included in the IEEE 802.21 framework in order to optimize the control signal communication. iPAS has been modelled, implemented, and evaluated via simulations. The results demonstrate that iPAS achieves better performance than the equal channel access mechanism over IEEE 802.11 DCF and a service differentiation scheme on top of IEEE 802.11e EDCA, in terms of fairness, throughput, delay, loss, and estimated PSNR. Additionally, both objective and subjective video quality assessment have been performed using a prototype system. 3. A QoS-based Downlink/Uplink Fairness Scheme, which uses the stereotypes-based structure to balance the QoS parameters (i.e. throughput, delay, and loss) between downlink and uplink VoIP traffic. The proposed scheme has been modelled and tested through simulations. The results show that, in comparison with other downlink/uplink fairness-oriented solutions, the proposed scheme performs better in terms of VoIP capacity and fairness level between downlink and uplink traffic

Adaptive buffer power save mechanism for mobile multimedia streaming

With the proliferation of wireless networks, the use of mobile devices to stream multimedia is growing in popularity. Although the devices are improving in that they are becoming smaller, more complex and capable of running more applications than ever before, there is one aspect of them that is lagging behind. Batteries have seen little development, even though they are one of the most important parts of the devices. Multimedia streaming puts extra pressure on batteries, causing them to discharge faster. This often means that streaming tasks can not be completed, resulting in significant user dissatisfaction. Consequently, effort is required to devise mechanisms to enable and increase in battery life while streaming multimedia. In this context, this thesis presents a novel algorithm to save power in mobile devices during the streaming of multimedia content. The proposed Adaptive-Buffer Power Save Mechanism (AB-PSM) controls how the data is sent over wireless networks, achieving significant power savings. There is little or no effect on the user and the algorithm is very simple to implement. The thesis describes tests which show the effectiveness of AB-PSM in comparison with the legacy power save mechanism present in IEEE 802.11. The thesis also presents a detailed overview of the IEEE 802.11 protocols and an in-depth literature review in the area of power saving during multimedia streaming. A novel analysis of how the battery of a mobile device is affected by multimedia streaming in its different stages is given. A total-power-save algorithm is then described as a possible extension to the Adaptive-Buffer Power Save Mechanism

Maximizing Resource Utilization In Video Streaming Systems

Video streaming has recently grown dramatically in popularity over the Internet, Cable TV, and wire-less networks. Because of the resource demanding nature of video streaming applications, maximizing resource utilization in any video streaming system is a key factor to increase the scalability and decrease the cost of the system. Resources to utilize include server bandwidth, network bandwidth, battery life in battery operated devices, and processing time in limited processing power devices. In this work, we propose new techniques to maximize the utilization of video-on-demand (VOD) server resources. In addition to that, we propose new framework to maximize the utilization of the network bandwidth in wireless video streaming systems. Providing video streaming users in a VOD system with expected waiting times enhances their perceived quality-of-service (QoS) and encourages them to wait thereby increasing server utilization by increasing server throughput. In this work, we analyze waiting-time predictability in scalable video streaming. We also propose two prediction schemes and study their effectiveness when applied with various stream merging techniques and scheduling policies. The results demonstrate that the waiting time can be predicted accurately, especially when enhanced cost-based scheduling is applied. The combination of waiting-time prediction and cost-based scheduling leads to outstanding performance benefits. The achieved resource sharing by stream merging depends greatly on how the waiting requests are scheduled for service. Motivated by the development of cost-based scheduling, we investigate its effectiveness in great detail and discuss opportunities for further tunings and enhancements. Additionally, we analyze the effectiveness of incorporating video prediction results into the scheduling decisions. We also study the interaction between scheduling policies and the stream merging techniques and explore new ways for enhancements. The interest in video surveillance systems has grown dramatically during the last decade. Auto-mated video surveillance (AVS) serves as an efficient approach for the realtime detection of threats and for monitoring their progress. Wireless networks in AVS systems have limited available bandwidth that have to be estimated accurately and distributed efficiently. In this research, we develop two cross-layer optimization frameworks that maximize the bandwidth optimization of 802.11 wireless network. We develop a distortion-based cross-layer optimization framework that manages bandwidth in the wire-less network in such a way that minimizes the overall distortion. We also develop an accuracy-based cross-layer optimization framework in which the overall detection accuracy of the computer vision algorithm(s) running in the system is maximized. Both proposed frameworks manage the application rates and transmission opportunities of various video sources based on the dynamic network conditions to achieve their goals. Each framework utilizes a novel online approach for estimating the effective airtime of the network. Moreover, we propose a bandwidth pruning mechanism that can be used with the accuracy-based framework to achieve any desired tradeoff between detection accuracy and power consumption. We demonstrate the effectiveness of the proposed frameworks, including the effective air-time estimation algorithms and the bandwidth pruning mechanism, through extensive experiments using OPNET

Providing Enhanced Framework to support QoS in Open Wireless Architecture

This paper presents a novel approach to support Quality of Service for Open Wireless Architectures (OWA), building a suitable framework over the top of the heterogeneous wireless MACs. It lets to enhance the existing QoS support provided by standard MAC protocols and it uses the contract model to guarantee QoS, taking into account the applications requests. It negotiates dynamically Application Level Contracts which will be translated seamlessly in Resource Level Contracts for the underlying network services. It receives the feedback by underlying network services to adjust the scheduling algorithms and policies to provide hard and soft guarantees. The framework comprises QoS Manager, Admission Control, Enhanced Scheduler, Predictor and Feedback System. The QoS manager component is able to dynamically manage available resources under different load conditions. A IEEE 802.11e Wireless LAN is simulated to show the benefits of this approach

Audio/Video Transmission over IEEE 802.11e Networks: Retry Limit Adaptation and Distortion Estimation

The objective of this thesis focuses on the audio and video transmission over wireless networks adopting the family of the IEEE 802.11x standards. In particular, this thesis discusses about the resolution of four issues: the adaptive retransmission, the comparison of video quality indexes for retry limit adaptation purposes, the estimation of the distortion and the joint adaptation of the maximum number of retransmissions of voice and video flows

Performance Evaluation of Video Streaming in an Infrastructure Mesh Based Vehicle Network

Most next-generation wireless networks are expected to support video stream- ing which constitutes the bulk of traffic on the Internet. This thesis evaluates the performance of video streaming in a vehicle network with an infrastructure wireless mesh network (WMN) backhaul. Several studies have investigated video quality per- formance primarily in single hop wireless networks and static WMNs. This thesis is based on those studies and conducts the study in relation to a network where the multi-hop features of the mesh network and mobility of the streaming clients may have substantial impact on the perceived video quality in the network. The study assumes a previously proposed vehicle network architecture con- sisting of an infrastructure WMN that serves as the mesh backhaul [2, 3]. A number of mesh routers (MRs) form the mesh backhaul using one of their two IEEE 802.11g radios whereas the other radio is used to communicate with the fast moving mesh clients (MCs). Selective MRs called mesh gateways (MGs) are connected to a wired network (e.g., the Internet, hereafter referred to as the core network) via a point-to- point link and provide gateway connectivity to the rest of the network. A server on the core network acts as a video server and streams individual video streams to the fast moving MCs. Upon deployment, network discovery occurs and segregates the network into a number of separate routing zones with each routing zone consisting of a single MG and all the MRs that use the MG as their gateway. A minimum-hop based routing protocol is used to enable seamless handover of MCs from one MR to another within a single zone. Simulation studies in this thesis inspects the network and video streaming performance within a single routing zone, assuming the handoff and inter-zone routing being taken care of by the routing protocol and only focus on the intra-zone packet forwarding and scheduling impacts. Hence, this study does not address cases where MCs move from one routing zone to another routing zone in the mobile network. In the first part of the study, we evaluate the performance of video streaming in the described network by studying performance metrics across different layers of the protocol stack. The number of video flows that can be supported by the network is experimentally determined for each scenario. In the second part, the thesis studies controllable network and protocol parameters\u27 ability to improve the network and video quality performance. Simulations are run in an integrated framework that includes network-simulator ns-2, NS-MIRACLE, and Evalvid