An analytical paradigm to compare routing strategies in an ATMmultimedia environment

We propose an analytical model for the study of two different routing strategies in an ATM network supporting multimedia traffic flow: the multimedia virtual circuit (MVC) and the independent virtual circuit (IVC). The first strategy consists of assigning a single virtual channel to all of the monomedia streams which make up the multimedia flows; the second strategy consists of multiplexing homogeneous monomedia streams belonging to different multimedia sources on the same virtual channel. With this aim, a multimedia source is modeled as an arrival process defined as the superposition of heterogeneous correlated arrival processes, each of which models one monomedia source. In order to take into account the intermedia relationships which exist in a multimedia stream, each monomedia source is modeled as an interrupted Bernoulli process in which the transition and the arrival probabilities are functions of the states of the other monomedia sources. A finite-buffer discrete-time approach is used in order to compare MVC and IVC performance when an aggregate of N heterogeneous multimedia sources loads the network. Performance is evaluated for each monomedia source in terms of loss probability and jitter probability density function. To assess the proposed paradigm, a case study is shown     

Performance evaluation of an adaptive-rate MPEG encoder matching IntServ traffic constraints

Promoting the evolution of the Internet from a simple data network to a true multiservice network constitutes a challenging task. To this end, the Internet Engineering Task Force (IETF) has set up the Integrated Services (IntServ) and Differentiated Services (DiffServ) Working Groups, with the goal of defining a next-generation Internet, in which traditional best-effort datagram delivery and additional enhanced quality of service delivery classes coexist. The IntServ framework, in particular, is designed to be used in the access network, and requires a traffic source with the capability of matching the traffic characteristics declared to the network, TSpec. We propose to use the rate control facility, usually implemented in current MPEG encoders to provide a constant bit rate, to shape the output traffic according to the declared TSpec while maintaining an acceptable perceived image quality. In order to assess this scenario, we introduce an SBBP/D/N/K queueing system, where the SBBP (switched batch Bernoulli process) emission is varied according to the quantizer scale parameter chosen by the addressed rate control mechanism. The analytical framework allows us: 1) to evaluate system performance in terms of both the marking probability of nonconforming output traffic and the quantization distortion introduced by the encoder; 2) to choose the TSpec parameters to be declared such that given performance parameters are respected.     

A Comparison of Adaptive Location Tracking Schemes in Personal Communications Networks

Various tracking strategies for the location of a mobile user in a cell system have been introduced in literature. Up to now they have been evaluated using simple mobility models that do not take into account the various directions in which users often move. In this paper we present a comprehensive study of distance-based, movement-based and multilayer strategies, from which it emerges that the effectiveness of these techniques depends not only on the call-to-mobility rate, a parameter typically referred to in literature, but also on the directional characteristics of the user mobility model.     

Performance analysis of an ATM multiplexer loaded with VBR trafficgenerated by multimode speech coders

Multimode coders are able to exploit the different characteristics of the speech waveform and to take into account the different peculiarities of background noise, thus allowing improvements in both signal reconstruction and network-offered load. In this context the variable rate code excited linear prediction (VR-CELP) coding, that is, a multimode variable bit rate (VBR) coding based on the CELP technique, has been introduced in the literature and is currently being considered for use in various applications, especially in the third-generation UMTS cellular systems. The target of the paper is to introduce an efficient and accurate framework allowing a network designer to analyze the impact of multimode VBR speech coding on the quality of service (QoS) provided by a wireless/wired ATM network. In order to capture the coder output characteristics, we propose to model a VR-CELP voice source by using a switched batch Bernoulli process (SBBP). More specifically, three models are introduced and compared in terms of accuracy and simplicity in determining network performance. As a result of the comparison, a four-state model has been chosen as the best tradeoff. The model is then used to analytically derive the loss probability and the jitter probability density function of an ATM multiplexer loaded by a number of VR-CELP sources. Finally, the proposed paradigm has been assessed in a case study where we demonstrate that, for a given output ATM link capacity and for a number of telecommunication services involving voice transmission, VR-CELP coding performs better than traditional on-off coding     

A novel analytical framework compounding statistical traffic modeling and aggregate-level service curve disciplines: network performance and efficiency implications

This paper demonstrates that higher network resource efficiency can be achieved by using resource management protocols which consider service disciplines based on service curves together with statistical traffic modeling. To this end, an appropriate analytical framework is introduced which allows calculation of the performance statistically guaranteed to any flow out of an aggregate. This feature enables the analytical framework to be applied to the elements of the core network where aggregates of traffic are considered instead of single flows in order to avoid scalability problems. Given that flows are modeled in the analytical framework through switched batch Bernoulli processes (SBBPs), the whole queueing system is denoted as SBBP/Sc/1/K. The performance is calculated in terms of loss probability and delay distribution. The proposed framework is applied in a significant multinode case study.     

Discrete-time model for multimedia correlated sources

A multimedia source model is presented. To capture the intermedia synchronisation requirements of the streams in the multimedia flow, the model is defined as the superposition of heterogeneous correlated monomedia arrival processes. Transition probability matrices and correlation functions are calculated to allow any designer to investigate network performance by means of well-known analytical techniques     

Traffic specifications for the transmission of stored MPEG video onthe Internet

Guarantees of quality-of-service (QoS) in the real-time transmission of stored video on the Internet is a challenging task for the success of many video on demand (VoD) applications. Two QoS classes have been specified by the IETF Integrated Services (intserv) Working Group: Guaranteed Services and Controlled-Load Services. For both of them, it is necessary to provide traffic sources with the capability of calculating the traffic characteristics to be declared to the network, Tspec, on the basis of a limited set of parameters statistically characterizing the traffic and the required level of QoS. The target of this paper is to develop an algorithm for the evaluation of the Tspec parameters which characterize the video stream when a given QoS is required. To this end an analytical framework modeling an MPEG stored-video server and the access network node is introduced. The video emission process is modeled with a switched batch Bernoulli process (SBBP), and performance in the video-server smoother is analytically evaluated. Then the token bucket at the network access point, loaded by the output traffic of the video-server smoother, is modeled to calculate the probability of marking nonconforming data packets     

Modeling Service Activation in a Multimedia Environment

The emergence of multimedia applications requires appropriate management and control activities to be provided and organized in an integrated framework. This article presents an architectural approach to the modeling of service activation processing in a multimedia environment.     

A Simple Analytical Framework for the Performance Evaluation of a Tree-Based Connection Rerouting Architecture in a UMTS Network

The enormous increase in wireless communications and the growing request for transmission bandwidth have led to the need to configure wireless access networks with cellular structures based on the use of micro- and pico-cells. Applying these structures means that handovers between neighboring cells are more frequent and therefore have to be carefully managed. A key issue in connection with this is the rerouting of the data flows directed to a user making a handover. In fact, the time interval needed to update all the routing tables in the crossover switches is critical because in this interval data have to be stored, and later forwarded once the route towards the new location has been determined. The paper considers a connectionless protocol, the Signaling Network Layer (SNL), which has been conceived for use in the Universal Mobile Telecommunication System (UMTS) context for connection rerouting purposes and is based on a tree-structured rerouting architecture. Through an analytical model based on a queueing network, its performance is analyzed in terms of the distribution of the rerouting delay. The proposed model is then applied to a case study to demonstrate its versatility and manageability and to get insight into the dimensioning of the rerouting architecture.