Evolution of QoS Control in Next Generation Mobile Networks

Next Generation Mobile Networks (NGMNs) constitute the evolution of mobile network architectures towards a common IP based network. One of the main research topics in wireless networks architectures is QoS control and provisioning. Different approaches to this issue have been described. The introduction of the NGMNs is a major trend in telecommunications, but the heterogeneity of wireless accesses increases the challenges and complicates the design of QoS control and provisioning. This chapter provides an overview of the standard architectures for QoS control in Wireless networks (e.g. UMTS, WiFi, WiMAX, CDMA2000), as well as, the issues on this all-IP environment. It provides the state-of-the-art and the latest trends for converging networks to a common architecture. It also describes the challenges that appear in the design and deployment of QoS architectures for heterogeneous accesses and the available solutions. The Evolved Core from 3GPP is analyzed and described as a suitable and promising solution addressing these challenges.

Quality of Service (QoS) Provisioning in Cognitive Wireless Ad Hoc Networks

Cognitive Radio (CR) is a next-generation wireless communication technology that improves the utilization of the overall radio spectrum through dynamic adaptation to local spectrum availability. In CR networks, unlicensed or Secondary Users (SUs) may operate in underutilized spectrum owned by licensed or Primary Users (PUs) conditional upon the PU encountering acceptably low interference levels. A Cognitive Wireless Ad Hoc Network (CWAN) is a multihop self-organized and dynamic network that applies CR technology for ad-hoc mode wireless networks that allow devices within range of each other to discover and communicate in a peer-to-peer fashion without necessarily involving infrastructure such as base stations or access points. Research into Quality of Service (QoS) in CWAN is still in its infancy. To date, there is only a perfunctory attempt to improve the data-link and network layers of the Open Systems Interconnection (OSI) reference model for CR hosts, and so this is the focus of this chapter. We present a discussion on the architecture, open issues and design approaches related to QoS provisioning in CWAN. Our discussion aims to establish a foundation for further research in several unexplored, yet promising areas in CWAN.

Towards Designing High-Throughput Routing Metrics for Wireless Mesh Networks

Routing is an essential mechanism for proper functioning of large networks, and routing protocols make use of routing metrics to determine optimal paths. The design of routing metrics is critical for achieving high throughput and we begin this chapter by proposing the design principles for routing metrics. These design principles are for ensuring the proper functioning of the network and achieving high throughput. We continue by giving a detail analysis of the existing routing metrics. We also look at the pitfalls of the existing routing metrics. We conclude the chapter by outlining the future research directions.

Scalable Wireless Mesh Network Architectures with QoS Provisioning

The wireless mesh network (WMN) is an economical solution to enable ubiquitous broadband services due to the advantages of robustness, low infrastructure costs, and enhancing coverage by low power. The wireless mesh network also has a great potential for realizing green communications since it can save energy and resources during network operation and deployment. With short-range communications, the transmission power in the wireless mesh networks is lower than that in the single-hop networks. Nevertheless, wireless mesh network should face scalability issue since throughput enhancement, coverage extension, and QoS guarantee are usually contradictory goals. Specifically, the multi-hop communications can indeed extend the coverage area to lower the infrastructure cost. However, with too many hops to extend coverage, the repeatedly relayed traffic will exhaust the radio resource and degrade the quality of service (QoS). Furthermore, as the number of users increases, throughput and QoS (delay) degrade sharply due to the increasing contention collisions. In this chapter, from a network architecture perspective we investigate how to overcome the scalability issue in WMNs, so that the tradeoff between coverage and throughput can be improved and the goal of QoS provisioning can be achieved. We discuss main QoS-related research directions in WMNs. Then, we introduce two available scalable mesh network architectures that can relieve the scalability issue and support QoS in WMNs for the wide-coverage and dense-urban coverage. We also investigate the optimal tradeoff among throughput, coverage, and delay for the proposed WMNs by an optimization approach to design the optimal system parameters.

Queuing Delay Analysis of Multi-Radio Multi-Channel Wireless Mesh Networks

Wireless mesh networking is becoming an economical means to provide ubiquitous Internet connectivity. In this chapter, we study wireless communications over multi-radio and multi-channel wireless mesh networks with IEEE 802.11e based ingress access points for local clients and point-to-point wireless links over non-overlapping channels for wireless mesh network backbones. We provide a set of algorithms to analyze the performance of such wireless mesh networks with wideband fading channels in various office building and open space environments and commonly-used Regulated and Markov On-Off traffic sources. Our goal is to establish a theoretical framework to predict the probabilistic end-to-end delay bounds for real-time applications over such wireless mesh networks.

Quality of Service (QoS) Routing in Mobile Ad Hoc Networks

A Mobile Ad hoc NETwork (MANET) consists of a collection of mobile nodes. They communicate in a multi-hop way without a formal infrastructure. Owing to the uniqueness such as easy deployment and self-organizing ability, MANET has shown great potential in several civil and military applications. As MANETs are gaining popularity day-by-day, new developments in the area of real time and multimedia applications are increasing as well. Such applications require Quality of Service (QoS) evolving with respect to bandwidth, end-to-end delay, jitter, energy etc. Consequently, it becomes necessary for MANETs to have an efficient routing and a QoS mechanism to support new applications. QoS provisioning for MANET can be achieved over different layers, starting from the physical layer up to the application layer. This chapter mainly concentrates on the problem of QoS provisioning in the perception of network layer. QoS routing aims at finding a feasible path, which satisfies QoS considering bandwidth, end-to-end delay, jitter, energy etc. This chapter provides a detailed survey of major contributions in QoS routing in MANETs. A few proposals on the QoS routing using optimization techniques and inter-layer approaches have also been addressed. Finally, it concludes with a discussion on the future directions and challenges in QoS routing support in MANETs.

Quality of Service Provisioning in the IP Multimedia Subsystem

The 3GPP IMS defines a network architecture that allows rapid provisioning of rich multimedia services. While standardization of the IMS core architecture is largely complete, there are several areas that are still to be addressed before effective deployment can be realized. In particular a QoS framework is required that efficiently manages scarce network resources, ensures reliability and differentiates IMS services from web-based services. This chapter reviews the most promising candidate resource management frameworks, performs architectural alignment and defines a set of generic terms and elements to provide a convenient point of departure for future research. This harmonization of standardized architectures is critical to avoid interoperability concerns that could cripple deployment. Further challenges are discussed, in particular the vertical and horizontal co-ordination of resources, and current research works that address these challenges are presented.

Video Distortion Estimation and Content-Aware QoS Strategies for Video Streaming over Wireless Networks

This chapter describes several advanced techniques for estimating the video distortion deriving from multiple video packet losses. It provides different usage scenarios, where the Peak Signal to Noise Ratio (PSNR) video metric may be used for improving the end user quality. The key idea of the presented applications is to effectively use the distortion information associated to each video packet. This allows one to perform optimal decisions in the selection of the more suitable packets to transmit. During the encoding process, the encoder estimates first the loss impact (for instance the amount of error propagation) of each packet. Afterwards, it generates side information as a “hint” for making video content aware transmission decisions. In this way, it is possible to define new scheduling schemes that give more priority to the packets with higher loss impact, and to assign fewer resources to the packets with lower loss impact. To this end, the usage of hint tracks, introduced in the MPEG-4 systems part, provides a syntactic means for storing scheduling information about media packets that significantly simplifies the operations of a streaming server. Moreover, the prioritization scheme may be used to minimize the overall error propagation under the delay constraint imposed by the video presentation deadline. The chapter also reviews recent research advances in the field of QoS mechanisms that adopt video specific metrics to improve the end user perceived quality.

Quality of Experience vs. QoS in Video Transmission

In legacy television services, user centric metrics have been used for more than twenty years to evaluate video quality. These subjective assessment metrics are usually obtained using a panel of human evaluators in standard defined methods to measure the impairments caused by a diversity of factors of the Human Visual System (HVS), constituting what is also called Quality of Experience (QoE) metrics. As video services move to IP networks, the supporting distribution platforms and the type of receiving terminals is getting more heterogeneous, when compared with classical video distributions. The flexibility introduced by these new architectures is, at the same time, enabling an increment of the transmitted video quality to higher definitions and is supporting the transmission of video to lower capability terminals, like mobile terminals. In IP Networks, while Quality of Service (QoS) metrics have been consistently used for evaluating the quality of a transmission and provide an objective way to measure the reliability of communication networks for various purposes, QoE metrics are emerging as a solution to address the limitations of conventional QoS measuring when evaluating quality from the service and user point of view. In terms of media, compressed video usually constitutes a very interdependent structure degrading in a non-graceful manner when exposed to Binary Erasure Channels (BEC), like the Internet or wireless networks. Accordingly, not only the type of encoder and its major encoding parameters (e.g. transmission rate, image definition or frame rate) contribute to the quality of a received video, but also QoS parameters are usually a cause for different types of decoding artifacts. As a result of this, several worldwide standard entities have been evaluating new metrics for the subjective assessment of video transmission over IP networks. In this chapter we are especially interested in explaining some of the best practices available to monitor, evaluate and assure good levels of QoE in packet oriented networks for rich media applications like high quality video streaming. For such applications, service requirements are relatively loose or difficult to quantify and therefore specific techniques have to be clearly understood and evaluated. By the mid of the chapter the reader should have understood why even networks with excellent QoS parameters might have QoE issues, as QoE is a systemic approach that does not relate solely to QoS but to the ensemble of components composing the communication system.

QoS in Vehicular Communication Networks

Vehicular communication networks (VCNs) have emerged as a key technology for next-generation wireless networking. DSRC/WAVE as a leading technology for VCN provides a platform for Intelligent Transportation System (ITS) services, as well as multimedia and data services. Some of these services such as active safety and multimedia services have special requirements for QoS provision. However, when providing QoS, the VCN characteristics are the cause for several new issues and challenges, especially when vehicles travel at high speeds of up to 200 km/h. These issues are addressed in the context of roadside networks and vehicular ad hoc (unplanned) networks (VANETs), including vehicle-to-vehicle (V2V) and vehicle-to-roadside (V2R) communications. Accordingly, plenty of solutions for provisioning QoS in VCNs have been classified in regards to VANETs and roadside networks, on the one hand, and to layer-2 and layer-3, on the other hand. Consequently, several QoS solutions, including medium access and routing protocols, are presented and discussed. Additionally, open research issues are discussed, with an objective to spark new research interests in the presented field.