IP Network Applications Research Articles

Fast Mode Decision Algorithm Through Inter-View Rate-Distortion Prediction for Multiview Video Coding System

Multiview video coding (MVC) has attracted great attention from industries and research institutes. MVC is used to encode stereoscopic video streams for 3D playout systems such as 3D television, digital cinema, and IP network applications. MVC is an extended version of H.264/AVC that improves the performance of multiview videos. Yet, when compared with single-view video coding, MVC consumes much more time when encoding large amounts of data. Speed-up algorithms, therefore, are essential for realizing related applications. This paper presents a fast mode decision algorithm to avoid the high computational complexity of MVC. The proposed approach aims to reduce candidate modes and make mode decision process more efficient. The minimum and maximum values of rate-distortion cost (RD cost) in the previously encoded view are used to compute a threshold for each mode in the current view. Compared with joint multiview video coding, the experimental results demonstrate that the proposed algorithm provides an average of 79% in time savings with negligible bit rate increase and peak signal-to-noise ratio decrease.

Multipath Adaptive Packet Dispersion for Voice Applications

Problem statement: The quality of Voice over IP applications is decided by the main factors like network capacity and technologies such as codec type, Packet Loss Concealment (PLC) and Forward Error Correction (FEC). Approach: In MPLS networks multiple Label Switched Paths (LSP) are established between MPLS ingress and egress nodes to enhance the network performance and QoS for subscribers. To enhance the Quality of Service, Multipath adaptive packet dispersion is proposed for voice applications in IP networks. Results: The trigger handler is proposed to check the balanced load in the system. If the network condition becomes unbalanced, the adaptive packet scheduler classifies the flows and routed to the best shortest paths with the help of proposed packet dispersion technique. Conclusion: The VoIP traffic is routed along the most adequate path that has enough resource to meet a given target QoS. Simulation results are reported to show the efficiency of the proposed technique for effective VOIP flows.

Optimizing QoS for Voice and Video using DiffServ-MPLS

Abstract: The new emerging QoS architectures are motivated by the desire to improve the overall performance of an IP network. Differentiated Services (Diffserv) define a model for implementing scalable differentiation of QoS in the Internet. Multiprotocol Label Switching (MPLS) is a fast label-based switching technique that offers new QoS capabilities for large scale IP networks. When an MPLS network supports DiffServ, traffic flows can receive class-based network treatment that provides bases for QoS guarantees. The objective of this work is to study the influence of the QoS mechanism via DiffServ-MPLS on network parameters such as jitter, delay and throughput. The comprehensive study showed general improvement in the throughput, jitter and delay particularly of voice and video transmission when using DiffServ-aware MPLS network as compared to pure IP only or MPLS only. Keywords: VOIP, MPLS, Diffserv QoS, OPNET 1. Introduction Various multimedia applications such as video streaming, VOIP and video conference are gaining demand bringing with it a massive congestion to the IP networks. With the emergences of multimedia applications in IP networks, bandwidth consumption has become a critical issue among the Internet community and Internet providers. Also a lot of the recent multimedia applications and services not only have bandwidth requirements, but also require other QoS assurances, like end-to-end delay, jitter or packet loss likelihood. These QoS requirements put new challenges on Internet service providers [1].

Performance analysis of multicast routing and wavelength assignment protocol with dynamic traffic grooming in WDM networks

The need for on-demand provisioning of wavelength-routed channels with service-differentiated offerings within the transport layer has become more essential because of the recent emergence of high bit rate Internet protocol IP network applications. Diverse optical transport network architectures have been proposed to achieve the above requirements. This approach is determined by fundamental advances in wavelength division multiplexing WDM technologies. Because of the availability of ultra long-reach transport and all-optical switching, the deployment of all-optical networks has been made possible. The concurrent transmission of multiple streams of data with the assistance of special properties of fiber optics is called WDM. The WDM network provides the capability of transferring huge amounts of data at high speeds by the users over large distances. There are several network applications that require the support of QoS multicast, such as multimedia conferencing systems, video-on-demand systems, real-time control systems, etc. In a WDM network, the route decision and wavelength assignment of lightpath connections are based mainly on the routing and wavelength assignment RWA. The multicast RWA's task is to maximize the number of multicast groups admitted or minimize the call-blocking probability. The dynamic traffic-grooming problem in wavelength-routed networks is generally a two-layered routing problem in which traffic connections are routed over lightpaths in the virtual topology layer and lightpaths are routed over physical links in the physical topology layer. In this paper, a multicast RWA protocol for capacity improvement in WDM networks is designed. In the wavelength assignment technique, paths from the source node to each of the destination nodes and the potential paths are divided into fragments by the junction nodes and these junction nodes have the wavelength conversion capability. By using the concept of fragmentation and grouping, the proposed scheme can be generally applied for the wavelength assignment of multicast in WDM networks. An optimized dynamic traffic grooming algorithm is also developed to address the traffic grooming problem in mesh networks in the multicast scenario for maximizing the resource utilization and minimizing the blocking probability. Copyright © 2011 John Wiley & Sons, Ltd.

Field-Trial Evaluation of Cross-Layer Effect Caused by All-Optical Wavelength Converters on IP Network Applications

Future Internet infrastructure will require the utilization of new all-optical devices able to enhance the use of fiber capacity. Nevertheless, before deploying such devices, it is necessary to test them under conditions similar to the ones of commercial networks and to evaluate their impact on real-world applications. In this work we investigate the performance of a tunable fiber four-wave mixing all-optical wavelength converter (AOWC) on a video-streaming carried through a field-trial network. This analysis is performed by measuring the packet-error rate (PER) degradation caused by the AOWC for different wavelength separations between the input and output optical carriers. To the best of our knowledge, this is the first time that such a cross-layer effect is systematically evaluated for an AOWC. A dynamic polarization controller was successfully used to prevent the FWM efficiency variations that were caused by the changes in the state-of-polarization of the video signal. Our results show that the AOWC introduced a maximum power penalty of 2.5 dB for wavelength separations of up to 12 nm. We also find that such a penalty is related to the optical signal-to-noise ratio degradation induced by the converter.

On Bandwidth-Efficient Overlay Multicast

In this paper, we propose a new multicast delivery mechanism for bandwidth-demanding applications in IP networks. Our mechanism, referred to as multiple-destination overlay multicast (MOM), combines the advantages of IP multicast and overlay multicast. We formulate the MOM routing problem as an optimization problem. We then design an algorithm based on Lagrangian relaxation on our formulation and propose a distributed protocol based on the algorithm. For network operators, MOM consumes less network bandwidth than both IP multicast and overlay multicast. For users, MOM uses less interface bandwidth than overlay multicast.

The effect of packet dispersion on voice applications in IP networks

Delivery of real time streaming applications, such as voice and video over IP, in packet switched networks is based on dividing the stream into packets and shipping each of the packets on an individual basis to the destination through the network. The basic implicit assumption on these applications is that shipping all the packets of an application is done, most of the time,over a single path along the network. In this work, we present a model in which packets of a certain session are dispersed over multiple paths, in contrast to the traditional approach. The dispersion may be performed by network nodes for various reasons such as load-balancing, or implemented as a mechanism to improve quality, as will be presented in this work. To study the effect of packet dispersion on the quality of voice over IP (VoIP) applications,we focus on the effect of the network loss on the applications, where we propose to use the Noticeable Loss Rate (NLR) as a measure (negatively) correlated with the voice quality. We analyze the NLR for various packet dispersion strategies over paths experiencing memoryless (Bernoulli) or bursty (Gilbert model) losses,and compare them to each other. Our analysis reveals that in many situations the use of packet dispersion reduces the NLR and thus improves session quality. The results suggest that the use of packet dispersion can be quite beneficial for these applications.

A rate control scheme for adaptive real-time applications in IP networks with lossy links and long round trip times

Currently there is no control for real-time traffic sources in IP networks. This is a serious problem because real-time traffic can not only congest the network but can also cause unfairness and starvation of TCP traffic. However, it is not possible to apply current solutions for Internet to the networks with high bandwidth-delay products and high bit error rates. The channel errors may result in inaccurate congestion control decisions and unnecessary rate throttles leading to severe performance degradation. This problem is amplified in the links with high bandwidth-delay products, since the link is inefficiently utilized for a very long time until the unnecessary rate throttle is recovered. In this paper, a new Rate Control Scheme, RCS, is introduced for real-time interactive applications in networks with high bandwidth-delay products and high bit error rates. RCS is based on the concept of using dummy packets to probe the availability of network resources. Dummy packets are treated as low priority packets and consequently they do not affect the throughput of actual data traffic. Therefore, RCS requires all the routers in the connection path to support some priority policy. A new algorithm is also proposed to improve the robustness of the RCS to temporal signal loss conditions. The delay-bound considerations for real-time traffic sources using RCS rate control scheme are also investigated. Simulation experiments show that in environments with high bandwidth-delay products and high bit error rates, RCS achieves high throughput performance without penalizing TCP connections.

Active networks for efficient distributed network management

The emerging next generation of routers exhibit both high performance and rich functionality, such as support for virtual private networks and QoS. To achieve this, per-flow queuing and fast IP filtering are incorporated into the router hardware. The management of a network comprising such devices and efficient use of the new functionality introduce new challenges. A truly distributed network management system is an attractive candidate to address these challenges. We describe how active network techniques can be used to allow fast and easy deployment of distributed network management applications in IP networks. We describe a prototype system where legacy routers are enhanced with an adjunct active engine, which enables the safe execution and rapid deployment of new distributed management applications in the network layer. This system can gradually be integrated in today's IP network, and allows smooth migration from IP to programmable networks. This is done with an emphasis on efficient use of network resources, which is somewhat obscure by many of today's high-level solutions.