Multimedia Satellite Networks Research Articles

Use of optimal wavelet packet decomposition for the long-term prediction of variable-bit-rate video traffic

This study systematically investigates the long-term prediction of online, real-time variable-bit-rate (VBR) video traffic, which is a key and complicated component of advanced predictive dynamic bandwidth control for future networks such as multimedia satellite networks. As per the time variation, non-linearity and long-range dependence in the VBR video traffic trace, a novel method of feature extraction based on multi-scale decomposition is proposed. After an analysis of the time–frequency distribution characteristics of the video trace, the wavelet packets that have the trait of arbitrary distinction and decomposition are selected. After space partition of wavelet packets, the best wavelet packet basis for feature extraction is picked. Based on the best basis, fast arbitrary multi-scale wavelet packet transform (WPT) can be done and each higher dimension wavelet coefficient matrix can be obtained. Then, wavelet coefficients prediction is done based on normalised least mean square error (NLMS) or least mean-support vector machine (LS-SVM) algorithm. The long-term prediction of the VBR video traffic is obtained through reverse wavelet transforms on the predicted wavelet coefficients. Numerical and simulation results are provided to validate the claims.

Simulation analyses of weighted fair bandwidth‐on‐demand (WFBoD) process for broadband multimedia geostationary satellite systems

AbstractAdvanced resource management schemes are required for broadband multimedia satellite networks to provide efficient and fair resource allocation while delivering guaranteed quality of service (QoS) to a potentially very large number of users. Such resource management schemes must provide well‐defined service segregation to the different traffic flows of the satellite network, and they must be integrated with some connection admission control (CAC) process at least for the flows requiring QoS guarantees. Weighted fair bandwidth‐on‐demand (WFBoD) is a resource management process for broadband multimedia geostationary (GEO) satellite systems that provides fair and efficient resource allocation coupled with a well‐defined MAC‐level QoS framework (compatible with ATM and IP QoS frameworks) and a multi‐level service segregation to a large number of users with diverse characteristics. WFBoD is also integrated with the CAC process. In this paper, we analyse via extensive simulations the WFBoD process in a bent‐pipe satellite network. Our results show that WFBoD can be used to provide guaranteed QoS for both non‐real‐time and real‐time variable bit rate (VBR) flows. Our results also show how to choose the main parameters of the WFBoD process depending on the system parameters and on the traffic characteristics of the flows. Copyright © 2005 John Wiley & Sons, Ltd.

Delay Control for Non-Real-Time Data in Interactive Multimedia Satellite Networks

Non-real-time packets in the interactive multimedia satellite network suffer inherent delay in cases of traffic congestion. Moreover, these packets may be discarded from the queue if they are not sent within a certain time. The objective of this study is to develop a real-time method in order to minimize the packet discard rate. Extensive evaluation results show that the proposed method performs very well.

Fixed Versus Adaptive Admission Control in Direct Broadcast Satellite Networks With Return Channel Systems

In this paper, as part of the adaptive resource allocation and management (ARAM) system (Alagoz, 2001), we propose an adaptive admission control strategy, which is aimed at combating link congestion and compromised channel conditions inherent in multimedia satellite networks. We present the performance comparisons of a traditional (fixed) admission control strategy versus the new adaptive admission control strategy for a direct broadcast satellite (DBS) network with return channel system (DBS-RCS). Performance comparisons are done using the ARAM simulator. The traffic mix in the simulator includes both available bit rate (ABR) traffic and variable bit rate (VBR) traffic. The dynamic channel conditions in the simulator reflect time variant error rates due to external effects such as rain. In order to maximize the resource utilization, both for fixed and adaptive approaches, assignment of the VBR services are determined based on the estimated statistical multiplexing and other system attributes, namely, video source, data transmission, and channel coding rates. In this paper, we focus on the admission control algorithms and assess their impact on quality-of-service (QoS) and forward link utilization of DBS-RCS. We show that the proposed adaptive admission control strategy is profoundly superior to the traditional admission control strategy with only a marginal decrease in QoS. Since the ARAM system has several parameters and strategies that play key roles in terms of the performance measures, their sensitivity analysis are also studied to verify the above foundations.

Interactive channel for multimedia satellite networks

Multimedia, including Internet traffic, can currently be multiplexed within the DVB/MPEG-2 formats and delivered direct to home users. Traditionally a slow terrestrial telephone link between the user and Internet service provider is used to request data. A direct return channel system will facilitate users' high-bit-rate bidirectional communication via satellite. The return link could be used for the fast Internet access or large data exchanges that will be necessary in a multimedia world. The satellite system not only removes the need for wires but also increases transfer speeds. Satellite interactive terminals can establish network connections via satellite and a ground-based hub. The DVB/MPEG-2 format carries up to 45 Mb/s in the forward link, and a multifrequency time-division multiple access scheme allows up to 2 Mbit/s in the return direction. The return channel of the interactive channel for multimedia satellite networks underwent final standardization by ETSI in early 2000. This article reviews the system concept of a typical implementation. The key features of the return channel air interface, from transmission parameter to login procedure, are explained. In general, Internet packets are expected to be carried via DVB/MPEG-2 in the forward direction and via ATM in the return direction. The IP transportation techniques are described.

Multimedia Satellite Networks and TCP/IP Traffic Transport

To meet an increasing demand for multimedia services and electronic connectivity across the world, satellite networks will play an indispensable role in the deployment of global networks. A number of satellite communication systems have been proposed using geosynchronous (GEO) satellites, medium earth orbit (MEO) and low earth orbit (LEO) constellations operating in the Ka-band and above. At these frequencies, satellite networks are able to provide broadband services requiring wider bandwidth than the current services at C or Ku-band. Most of the next-generation broadband satellite systems will use ATM or "ATM-like" switching with onboard processing to provide full two-way services to and from earth stations. The new services gaining momentum include mobile services, private intranets, and high-data-rate internet access carried over integrated satellite-fiber networks. Several performance issues need to be addressed before a transport layer protocol like TCP can satisfactorily work over satellite ATM for large delay-bandwidth networks. The authors review the proposed satellite systems and discuss challenges such as traffic management and QoS requirements for broadband satellite ATM networks. The performance results of TCP enhancements for Unspecified Bit Rate over ATM (ATM-UBR+) for large bandwidth-delay environments with various end system policies and drop policies for several buffer sizes are presented.

Performance analysis of multiple access protocols for multimedia satellite networks

In this paper, several TDMA-based packet multiple access protocols are studied and evaluated in the geostationary satellite environment. The distributed queueing random access protocol, DQRAP, originally proposed for HFC networks is adapted to the satellite environment. Another protocol, the announced retransmission random access protocol, ARRA, proposed for wireless networks is also studied. Both protocols are modeled and simulated in a VSAT network context. We then propose a new protocol which combines the advantages of both studied schemes and is more adapted to interactive multimedia applications over satellite uplinks. The generalized retransmission announcement protocol, GRAP, regroups the immediate access by contention at low loads, and the reservation access. At higher loads, to achieve a better channel efficiency. An analytical model is proposed to calculate the channel throughput obtained by GRAP under different loading conditions. Simulation results illustrate an improved throughput/delay characteristics and a higher protocol stability compared to both DQRAP and ARRA. Enhanced versions of the protocol are also proposed and evaluated to further improve its efficiency, with reasonable additional complexity.