Cross-layer Scheduling with Feedback for QoS Support

AbstractNext-Generation Networks (NGNs) will support Quality of Service (QoS) over a mixed wired and wireless IP-based infrastructure. A relative model of service differentiation in Differentiated Services architecture is a scalable solution for delivering multimedia traffic. However, considering the dynamic nature of radio channels typically, it is difficult to achieve a given service provisioning working at the IP and lower layers separately as in the classical approach, without a run-time adaptation of the system towards the target quality. This work describes an IP cross-layer scheduler able to support a Proportional Differentiation Model (PDM) for delay guarantees with content-awareness, also over wireless. The key idea is to leverage feedbacks from the lower layers about the actual delays experienced by packets in order to tune at run-time the priority of the IP service classes in a closed-loop control with the objective of supporting a PDM at the network node on the whole, considering the cumulative latency in crossing the first three layers of the protocol stack, as relevant for the end-user. A simulation analysis demonstrates the prominent improvements in reliability and robustness of the proposal in the case of time-variant performance of the MAC and PHY layers with respect to the classical non-cross-layer approach and the open- loop control. Furthermore, considerations on the required functionality and likely deployment scenarios highlight the scalability and backward compatibility of the designed solution in supporting the concept of network transparency for the delivering of critical applications, as of the e-health domain

QoS multicast for DiffServ on MPLS and IP platforms

Multicasting has become increasingly important with the emergence of Internet-based applications such Internet protocol (IP) telephony, audio/video conferencing, distributed databases and software upgrading. IP Multicasting is an efficient way to distribute information from a single source to multiple destinations at different locations. One of the challenges the Internet is facing today is to keep the packet forwarding performance up with the skyrocketing demand for bandwidth. On the other hand, the MultiProtocol Label Switching (MPLS), which is an Internet Engineering Task Force (IETF) framework, combines the flexibility of layer 3 routing and layer 2 switching, which enhances network performance in terms of scalability, computational complexity, latency and control message overhead. Besides, MPLS offers a vehicle for enhanced network services such as Quality of Services (QoS)/Class of Service (CoS), Traffic Engineering and Virtual Private Networks (VPNs). In this thesis, we present a new Fair Share Policy (FSP), which is a traffic policing mechanism that utilizes Differentiated Services (DiffServ) to solve the problems of QoS and congestion control. We compare the QoS performance of IP and MPLS multicasting, given their particular constraints. In order to achieve the required QoS, different techniques of reliable multicasting are adapted, such as Forward Error Correction (FEC), Automatic Repeat Request (ARQ) or Hybrid FEC/ARQ with multicast or unicast repairs mechanisms so as to mitigate the effect of errors as well as packet loss. This reliable multicast is for both IP and MPLS platforms with Diffserv. Analytical and simulation models are suggested and employed. The results provide insights into the comparisons between IP multicast in MPLS networks using FSP and plain IP multicasting using the same policy when DiffServ is adopted and when reliable multicast is considered. This comparison will be based on the following QoS measures: total packet delay, delay jitter and residual packet loss probability. Analysis and simulation tools are used to evaluate our fair share policy (FSP) for different homogeneous (when all routers are identical in their capabilities) and heterogeneous (when routers have different capabilities) network scenarios

Towards scalable end-to-end QoS provision for VoIP applications

The growth of the Internet and the development of its new applications have increased the demand for providing a certain level of resource assurance and service support. The concept of ensuring quality of service (QoS) has been introduced in order to provide the support and assurance for these services. Different QoS mechanisms, such as integrated services (IntServ) and differentiated services (DiffServ), have been developed and introduced to provide different levels of QoS provision. However, IntServ can suffer from scalability issues that make it infeasible for large-scale network implementations. On the other hand, the aggregated-based per-flow technique of DiffServ does not provide such an end-to-end QoS guarantee. Recently, the IETF have proposed a new QoS architecture that implements IntServ over DiffServ in order to provide an end-to-end QoS for scalable networks. Hence, it became possible to provide and support a certain level of QoS for some delay sensitive and bandwidth-demanding applications such as voice over Internet Protocol (VoIP). With regard to VoIP applications, delay, jitter and packet loss are crucial issues that have to be taken into consideration for any VoIP system design and such parameters need a distinct level of QoS support

Implementation of QoS onto virtual bus network

Quality of Service (QoS) is a key issue in a multimedia environment because multimedia applications are sensitive to delay. The virtual bus architecture is a hierarchical access network structure that has been proposed to simplify network signaling. The network employs an interconnection of hierarchical database to support advanced routing of the signaling and traffic load. Therefore, the requirements and management of quality of service is important in the virtual bus network particularly to support multimedia applications. QoS and traffic parameters are specified for each class type and the OMNeT model has been described

Quality of service assurance for the next generation Internet

The provisioning for multimedia applications has been of increasing interest among researchers and Internet Service Providers. Through the migration from resource-based to service-driven networks, it has become evident that the Internet model should be enhanced to provide support for a variety of differentiated services that match applications and customer requirements, and not stay limited under the flat best-effort service that is currently provided. In this paper, we describe and critically appraise the major achievements of the efforts to introduce Quality of Service (QoS) assurance and provisioning within the Internet model. We then propose a research path for the creation of a network services management architecture, through which we can move towards a QoS-enabled network environment, offering support for a variety of different services, based on traffic characteristics and user expectations

Network emulation focusing on QoS-Oriented satellite communication

This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication