Haruo Akimaru

A practical dimensioning method for ATM systems

In this paper, a simplified practical method for dimensioning asynchronous transfer mode (ATM) systems is proposed. Packet switching services are classified into two categories: connection-oriented packet switching (COPS) with quality of service (QoS) guaranteed and connection-less packet switching (CLPS) on a best effort basis. A new control scheme is proposed for maintaining the cell-level QoS requirement for the COPS even in overload conditions. A dimensioning method is also proposed for the system where the COPS is served with nonpreemptive priority over the CLPS. The methods proposed are expected to contribute to the realization of robust and economical ATM systems.

Price Optimization of Contents Delivery Systems with Priority

For data delivery systems such as video-on-demand service, an optimum design is presented to maximize the revenue of the system with priority classes. The willingness-to-pay (WTP) is introduced for a measure of utility (price), and the optimum design is discussed to maximize the revenue. For the system with two priority classes, the optimum condition is given in terms of the traffic load, waiting time for service and pricing for the priority and non-priority classes. In this paper, we use the WTP as the measure of pricing. And we would like to examine the optimum design to propose the optimum pricing methods for timebase and flat-base. In this paper, using the WTP, the utility (price) of the data delivery system has been quantified, and the optimum condition to maximize the revenue of the system has been analyzed. From the numerical examples, the optimum condition for the service grade (waiting time for service) and pricing for priority and non-priority classes has been discussed.

Multi-Class Input Models

This chapter deals with traffic models with multi-class input which appear in the ISDN (integrated services digital network) and LAN (local area network). These include batch arrival, priority queue, multi-dimensional, mixed loss and delay, multi-queue models, etc.

Practical design methods for ATM systems

The basic service categories necessary for the information highway, namely, VLL (virtual leased line), VCS (virtual circuit switching), COPS (connection oriented packet switching), and CLPS (connectionless packet switching), have been proposed [9]. In this paper, we propose simplified practical design and control methods for the ATM systems to implement these categories of service. VLL may be realized by a cross-connecting technology of transmission systems. For VCS, the transmission speed is designed so as to satisfy the average call loss rate by applying a multidimensional traffic model. For COPS, using the call blocking probability as the call level QoS (quality of service), the maximum number of virtual channels (VCs) is designed to satisfy the QoS requirement. With the cell level QoS, the cell loss rate and mean cell delay, the transmission line speed and the buffer size are designed to satisfy the QoS requirement. In a system integrating COPS and CLPS, COPS is given nonpreemptive priority over CLPS, the latter being served on a best effort basis. In overload traffic conditions, a control method is proposed in which the number of assigned VCs is reduced so as to meet the cell level QoS requirement.

Practical QoS design for packet/cell switching systems

For packet/cell switching of connection-less and connection oriented modes, practical QoS design methods are presented. Identification of bursty traffic by the CR-H2 (correlated 2nd order hyper-exponential distribution) convenient for practical measurements is proposed, which is equivalent to the 2-phase MMPP (Markov modulated Poisson process). The formulas including 3rd moment of the packet delay are presented, using which the mean and peak packet delays are calculated. A simplified QoS design for COPS (connection oriented packet switching) is proposed for the ATM (asynchronous transfer mode). Numerical examples and simulation results are shown to demonstrate the proposed methods.

Alternative Routing Systems

In the alternative routing system, if all servers are busy in a certain route, blocked traffic is carried by an alternative route. The alternative routing system is a limited availability system, and various practical approximations have been studied, as well as the exact solution by numerical analysis. The typical methods are described in this chapter.

Advanced Teletraffic Models

As tools for analyzing advanced teletraffic systems, this chapter introduces the main results of the modified diffusion approximation, and matrix analytic method. As examples for latest teletraffic systems, performance analyses of the packet multiplexer system in the ISDN and ATM, as well as token ring and CSMA/CD LANs are also described.

Non-Markovian Models

A teletraffic system with the interarrival time or service time not exponentially distributed, are called a non-Markovian model. This chapter presents the main results for non-Markovian models for which relatively simple solutions are obtained. We shall begin by introducing the renewal process.