Olga Casals

Statistical multiplexing of VBR sources: a matrix-analytic approach

Abstract In this paper we propose a versatile point process as model for a large class of variable bit rate sources and their superpositions. The process belongs to the class of discrete-time batch Markovian arrival processes (D-BMAP). Its use leads to computationally tractable and accurate solutions for various performance measures of the related statistical multiplexer: buffer occupancy distribution, cell loss probability, conditional cell loss probability. Moreover it is shown that the output process of the multiplexer belongs to the same class of processes.

Performance analysis of statistical multiplexing of VBR sources

The authors propose a versatile point process as a model for a large class of variable bit rate sources and their superpositions. The process belongs to the class of discrete-time batch Markovian arrival processes. Its use leads to computationally tractable and accurate solutions for the following performance measures of the related statistical multiplexer: buffer occupancy distribution, cell loss probability, and conditional cell loss probability. It is shown that the output process of the multiplexer belongs to the same class of processes.<<ETX>>

Quality of Future Internet Services

This book is the final report of COST – Cooperation europeenne dans le domaine de la recherche scientifique et technique , Action 263 – Quality of future Internet Services.

A review of voice, data and video traffic models for ATM

This paper describes the main statistical features of voice, data and video sources, defines a set of selection criteria for selecting source models for these sources, describes a number of relevant source models for representing these sources and recommends the best source models based on the results of the parameterisation of these models from measured data.

Performance Analysis of IP Micro-mobility Handoff Protocols

Micro-mobility protocols have been proposed to provide seamless local mobility support. This paper focuses on the performance of the handoff schemes of two candidates for micro-mobility protocols, namely HAWAII and Cellular IP. For each handoff scheme, a simple analytical model is developed for the evaluation of two characteristic performance measures: the packet loss probability during handoff and the extra delay experienced by packets that are involved in the handoff. Application of these models allows a comparison of two important handoff schemes: the Multiple Stream Forwarding scheme of HAWAII and the Semi-soft Handoff scheme of Cellular IP.

Performance evaluation of layer 3 low latency handoff mechanisms

This paper investigates the performance of two Layer 3 low latency handoff mechanisms proposed by the IETF, namely Pre- and Post-Registration. These protocols use Layer 2 triggers to reduce the built-in delay components of Mobile IP. We propose a simple analytical model that allows assessing the packet loss and the delay characteristics of these mechanisms. We describe several handoff implementations over a wireless access based on the IEEE 802.11 standard and analyze several implementation issues. Finally we study the scalability of the protocols using an OPNET simulation.

An exact model for the multiplexing of worst case traffic sources

In this paper we analyse a multiplexer handling a number of identical and independent Worst Case Traffic (WCT) sources. Each WCT source produces a periodic stream of cells consisting of a constant number of back-to-back cells followed by a silent period of constant duration. The WCT can model the traffic produced by a “malicious” user who sends an ON/OFF traffic where a burst of back-to-back cells whose length is the largest compatible with the tolerance introduced in the control function alternates with an idle period whose length is the smallest compatible with the policed peak cell rate. WCT can also model, for example, the traffic produced by some ATM Adaptation Layer multiplexing schemes in the Terminal Equipment.

Low latency handoff mechanisms and their implementation in an IEEE 802.11 network

In this paper we compare the performance of two low latency handoff protocols for MIPv4, Pre- and Post-Registration Handoff. These mechanisms proposed by the IETF aim at improving the performance of Hierarchical Mobile IP with respect to handoff latency and packet loss. We propose an analytical model to study the influence of various system parameters on the performance of the two protocols, followed by a comparison of the two schemes. We describe several handoff implementations over a wireless access based on the IEEE 802.11 standard and analyze them by means of an ns simulation.

Performance Analysis of a Forwarding Scheme for Handoff in HAWAII

Demand for mobile network access is having a huge increase nowadays. Cellular networks are being deployed to cope with a high number of users. Several IP micro-mobility protocols have been proposed to handle routing and handoffs inside cellular networks. In this paper the HAWAII micro-mobility protocol is analyzed by means of an analytical model. A detailed description of the handoff procedure is given and illustrated by means of traces obtained from simulation. Several of the system details are taken into account in the analytical model. This allows us to investigate the influence of various system parameters (e.g. cell overlap area, beacon latency, forwarding buffer capacity, etc.) on the system performance for constant bit rate (UDP) traffic. The results are validated by means of simulation results obtained with the network simulator (ns).

Stochastic models of space priority mechanisms with Markovian arrival processes

In this paper, we study a single-server queue with finite capacity in which several space priority mechanisms are implemented. The arrival process is the general Markovian arrival process (MAP) which has been used to model the bursty arrival processes commonly arising in communication applications. The service times are generally distributed. These buffer mechanisms enable the Asynchronous Transfer Mode (ATM) layer to adapt the quality of the cell transfer to the quality of service requirements of the specific broadband ISDN services and to improve the utilization of the network resources. This is done by a selective discarding of cells according to the class they belong to. Computable expressions for various performance parameters are obtained. Numerical results are given for the case of a two-state Markov-modulated Poisson process (MMPP) and deterministic service times. The values derived can be used to evaluate the benefits of using priorities in an ATM network when the traffic is bursty and to make a comparative study of the buffer mechanisms. These results extend the models previously developed, which were limited to Poisson arrivals.