This paper describes a framework for admission control for a packet-based network where the decisions are taken by edge devices or end-systems, rather than resources within the network. The decisions are based on the results of probe packets that the end-systems send through the network, and require only that resources apply a mark to packets in a way that is load dependent. One application example is the Internet, where marking information is fed back via an ECN bit, and we show howthis approach allows a rich QoS framework for ows or streams. Our approach allows networks to be explicitly analysed, and consequently engineered.

High-speed packet networks will begin to support services that need Quality-of-Service (QoS) guarantees. Guaranteeing QoS typically translates to reserving resources for the duration of a call. We propose a statedependent routing scheme that builds on any base stateindependent routing scheme, by routing flows which are blocked on their primary paths (as selected by the state-independent scheme) onto alternate paths in a manner that is guaranteed---under certain Poisson assumptions---to improve on the performance of the base state-independent scheme. Our scheme only requires each node to have state information of those links that are incident on it. Such a scheme is of value when either the base state-independent scheme is already in place and a complete overhaul of the routing algorithm is undesirable, or when the state (reserved flows) of a link changes fast enough that the timely update of state information is infeasible to all possible call-originators. The performance improvements ...

In this paper we consider the analysis of call blocking at a single resource with differing capacity requirements as well as differing arrival rates and holding times. We include in our analysis trunk reservation parameters which provide an important mechanism for tuning the relative call blockings to desired levels. We base our work on an asymptotic regime where the resource is in heavy traffic. We further derive, from our asymptotic analysis, methods for the analysis of finite systems. Empirical results suggest that these methods perform well for a wide class of examples. LOSS NETWORKS; INTEGRATED NETWORKS; TIME-SCALE SEPARATION; TRUNK RESERVATION; BLOCKING PROBABILITIES AMS 1991 Mathematics Subject Classification Primary: 60K20 Secondary: 60K15, 60K30, 68M20, 90B12 1 Introduction Recent developments in communication networks have lead to much interest in systems where traffic of widely differing characteristics is integrated. In this paper we address one of the probabilistic issue...

This paper examines the connection between loss networks without controls and Markov random field theory. The approach taken yields insight into the structure and computation of network equilibrium distributions, and into the nature of spatial dependence in networks. In addition, it provides further insight into some commonly used approximations, enables the development of more refined approximations, and permits the derivation of some asymptotically exact results. 1

Wireless private branch exchange (PBX) system offers wireless telephone access in an office environment. In a WPBX, several base stations are connected to the PBX, and the PBX is connected to the public switched telephone network (PSTN). Since only a small number of telephones are expected to be busy at the same time, the capacity (number of the external lines) between the PBX and the PSTN is typically smaller than the sum of the capacities (radio channels) of the individual base stations. It is important to determine the capacity of the WPBX to optimize the performance of the system. This paper proposes an analytic model and a simulation model for WPBX resource planning. Based on the workload to the WPBX, our study provides the guidelines to determine the capacities of the PBX and the base stations. 1 Introduction One of the major trends in enterprise networking is to add mobility solutions to the existing corporate communication systems and integrate them as seamlessly as possible [...

This paper proposes an analytic model to compute the loss probability for Wireless Local Loop (WLL) with finite number of subscribers. The number of trunks between the WLL concentrator and the base station controller is less than the total number of radio links in the WLL. This model is validated against the simulation results. The execution of our model is ecient compared with simulation. However, its time complexity is higher than several existing analytic models that approximate the loss probability for WLL. Therefore, we design an ecient WLL network planning procedure (in terms of time complexity and accuracy) that utilizes the approximate analytic models to provide small ranges for selecting the values of system parameters. Our model is then used to accurately search the operation points of WLL within the small ranges of the system parameter values. This paper proves that the performance of WLL with limited trunk capacity and finite subscriber population is not affected by the call holding time distributions. Based on our model, we illustrate WLL design guidelines with several numerical examples.

Motivated by emerging applications in workforce management, we consider a class of revenue management problems in systems with reusable resources. The corresponding applications are modeled using the well-known loss network systems (sometime also called the stochastic knapsack model). We use an extremely simple linear program (LP) that provides an upper bound on the best achievable expected long-run revenue rate. The optimal solution of the LP is used to devise a conceptually simple control policy that we call the class selection policy(CSP). Moreover, the LP is used to analyze the performance of the CSP policy. We obtain the first control policy with uniform performance guarantees. That is, the CSP policy is guaranteed to have expected long-run revenue rate that is at least half of the best achievable. Moreover, as the ratio between the capacity of the system and the maximum resource requirement grows to infinity, the CSP policy is asymptotically optimal, regardless of any other parameter of the problem. The asymptotic performance analysis that we obtain is more general than existing results in several important dimensions. It is based on several novel ideas that we believe will be useful in other settings.

This paper is concerned with evaluating the performance of loss networks. Accurate determination of loss network performance can assist in the design and dimensioning of telecommunications networks. However, exact determination can be dicult and generally cannot be done in reasonable time. For these reasons there is much interest in developing fast and accurate approximations. We develop a reduced load approximation which improves on the famous Erlang xed point approximation (EFPA) in a variety of circumstances. We illustrate our results with reference to a range of networks for which the EFPA may be expected to perform badly. 1 Introduction We shall use the standard model for a circuit-switched teletrac network. The network consists of a nite set of links J and the j-th link comprises a co-operative group of C j circuits. Upon connection of a call an end-to-end route is established such that a call initiated on route r seizes a number, a j;r , of circuits from one or more ...

The analysis of stochastic loss networks has long been of interest in computer and communications networks and is becoming important in the areas of service and information systems. In traditional settings, computing the well known Erlang formula for blocking probability in these systems becomes intractable for larger resource capacities. Using compound point processes to capture stochastic variability in the request process, we generalize existing models in this framework and derive simple asymptotic expressions for blocking probabilities. In addition, we extend our model to incorporate reserving resources in advance. Although asymptotic, our experiments show an excellent match between derived formulas and simulation results even for relatively small resource capacities and relatively large values of blocking probabilities.

The analysis of stochastic loss networks has long been of interest in computer and communications networks and is becoming important in the areas of service and information systems. In traditional settings, computing the well known Erlang formula for blocking probability in these systems becomes intractable for larger resource capacities. Using compound point processes to capture stochastic variability in the request process, we generalize existing models in this framework and derive simple asymptotic expressions for blocking probabilities. In addition, we extend our model to incorporate reserving resources in advance. Although asymptotic, our experiments show an excellent match between derived formulas and simulation results even for relatively small resource capacities and relatively large values of blocking probabilities.