Tight Upper Bounds for Cell Loss Probabilities and Required Bandwidth Estimation in ATM Multiplexers

Estimating the cell loss probability in an ATM multiplexer is a key issue in network management and traffic control such as call admission control and bandwidth allocation. In this paper, we derive a new approximation to estimate the total and individual cell loss probabilities in an ATM multiplexer fed by a superposition of heterogeneous on-off sources with exponentially distributed on and off periods. Based on this approximation, a simple and accurate method is proposed to estimate the aggregate required bandwidth by a given mix of traffic to guarantee a given cell loss probability.

An important parameter in ATM-based network design and management is the cell loss probability in ATM multiplexers. However, it depends on many unknown and unpredictable traffic parameters such as burst length distribution, mean rate, etc. In this paper, we propose a simple and robust fuzzy-based algorithm to predict the cell loss probability in large-sized systems based only on both a small amount of information from small-sized systems, and the asymptotic behavior for very large systems. Numerical results show that the value predicted by this algorithm is quite accurate. The application of the proposed algorithm to call admission control is also presented.

Estimating the cell loss probability in an ATM multiplexer is one of the most important problems concerning congestion control and bandwidth management in an ATM-based BISDN. We propose a new approach to estimating the cell loss probability in an ATM multiplexer. We use the Markov modulated deterministic process (MMDP) to approximate the actual arrival process and then model the ATM multiplexer as an MMDP/D/1/K queueing system. Using queueing analysis, we derive a formula for the cell loss probability expressed in terms of the limiting probabilities of a Markov chain. We propose two approximation methods based on the results of the analysis. The actual arrival process is approximated by an (M+1)-state MMDP in the first method and by a two-state MMDP in the second. The major advantages of both methods are simplicity, computational efficiency, and numerical stability. The most attractive feature of the second method is that the cell loss probability can be expressed in closed form. Numerical and simulation results show that the first method is sufficiently accurate for all cases in which burst-level congestion is the main contributing factor to cell loss, while the closed-form formula is sufficiently accurate for applications where the average burst length is large (such as large file transfers, image retrievals, etc.).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analyzing and estimating the cell loss probability in an ATM multiplexer is one of the most important problems concerning traffic control and resource management in an ATM‐based B‐ISDN. In this paper, an extension of the discrete fluid‐flow technique is proposed to calculate the cell loss probability of an ATM multiplexer fed by a 2‐state MMDP source. This technique is also used to analyze and estimate the cell loss performance of an ATM multiplexer loaded with homogeneous On‐Off sources. Numerical calculation and simulation results indicate that the method is both accurate and computationally efficient.

Estimating cell loss probability (CLP) in real time for achieving satisfactory call admission control (CAC) remains an important research problem. In estimating CLP which is often specified to be less than 10/sup -9/, fuzzy based techniques have been found to be more promising than crisp statistical techniques. In this paper, we propose a novel fuzzy logic algorithm based on the /spl alpha/-cuts of equivalence relations to estimate CLP in real time for self-similar ATM networks. The /spl alpha/-cuts of fuzzy sets are used to construct the membership functions of the input and output variables and to induce necessary fuzzy rules. The proposed fuzzy approach is validated by comparing the estimated values of CLP with the theoretical values. The new approach not only estimates accurate real time CLP, but also achieves it by using fewer theoretical data.

The authors propose a call admission control scheme based on a method of estimating cell loss quality for individual bursty traffic sources. The estimate is expressed in terms of virtual cell loss probability, which may be defined by two traffic characteristic parameters alone: peak and mean rate. The approach is suitable for the estimation of real cell loss probability in heterogeneous and homogeneous traffic models when burst length is larger than buffer capacity. The concept of virtual cell loss probability is extended to the individual call level so as to be able to estimate the quality of service (QOS) provided to individual calls. A virtual bandwidth method is used to develop a practical call admission control system. Quality is ensured by combining a traffic clustering scheme, with a scheme for assigning individual clusters to subcapacities of a link. Priority levels are presented in terms of the class of QOS required, i.e., deterministic or statistical, and the allocation of virtual bandwidth is discussed in terms of both QOS class and traffic characteristics.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

We discuss the call admission control problem in ATM networks. In particular, we focus on a single node in isolation as a model for the ATM multiplexer, and consider the cell loss probability and the average cell queueing delay in the multiplexer as the quality of service (QoS) performance measures. Difficulties often arise in the analysis for such systems due to the so-called curse of dimensionality in calculating some integer-parametered functions, where the integer parameter represents the system size or dimension. Our basic idea is to develop global rational approximation for such systems. Various examples presented in the previous papers have demonstrated the power of the approach. In this paper we apply the rational approximation method to the call admission problem in ATM networks.

The main contributions of this paper are two-fold. First, we prove fundamental, similarly behaving lower and upper bounds, and give an approximation based on the bounds, which is effective for analyzing ATM multiplexers, even when the traffic has many, possibly heterogeneous, sources and their models are of high dimension. Second, we apply our analytic approximation to statistical models of video teleconference traffic, obtain the multiplexing system's capacity as determined by the number of admissible sources for given cell-loss probability, buffer size and trunk bandwidth, and, finally, compare with results from simulations, which are driven by actual data from coders. The results are surprisingly close. Our bounds are based on large deviations theory. The main assumption is that the sources are Markovian and time-reversible. Our approximation to the steady-state buffer distribution is called Chenoff-dominant eigenvalue since one parameter is obtained from Chernoffs theorem and the other is the system's dominant eigenvalue. Fast, effective techniques are given for their computation. In our application we process the output of variable bit rate coders to obtain DAR(1) source models which, while of high dimension, require only knowledge of the mean, variance, and correlation. We require cell-loss probability not to exceed 10/sup -6/, trunk bandwidth ranges from 45 to 150 Mb/s, buffer sizes are such that maximum delays range from 1 to 60 ms, and the number of coder-sources ranges from 15 to 150. Even for the largest systems, the time for analysis is a fraction of a second, while each simulation takes many hours. Thus, the real-time administration of admission control based on our analytic techniques is feasible.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Wireless sensor networks (WSNs) use sensors to monitor phenomena such as temperature, humidity, groundwater levels and transmit this information to a base station using wireless channels. WSNs find applications in military, ecological, and health-related areas. A hybrid wireless sensor network includes two networks: an ad hoc wireless network and a wireless sensor network. The nodes in the ad hoc network act as base stations conducting surveillance on the WSN. In this dissertation, we focus on the key management issues in hybrid wireless sensor networks. The key management issues in hybrid wireless sensor networks can be divided into three categories according to which layer they affect: ad hoc network layer, wireless sensor network layer, and integrated cross layer. At the ad hoc network layer, we propose two elliptic curve discrete logarithm problem (ECDLP) based schemes for secure group communication (SGC). Unlike the vast majority of secure group communication protocols using the discrete logarithm problem (DLP) based Diffie-Hellman as the basic key agreement protocol, our solutions use the ECDLP-based Diffie-Hellman protocol. We also extend our research on secure group communication to the wireless sensor network layer. We formally define the grouping and secure group communication problems in WSNs. We further propose and evaluate four centralized group rekeying (CGK) schemes for SGC in WSNs. Our proposed key management protocol at the integrated cross layer, mKeying, includes two schemes, a key distribution scheme, KeyDist, supporting multiple base stations in the network, and a centralized key revocation scheme, KeyRev, for removing compromised sensor nodes from the sensor network. Through these protocols for key distribution, key revocation, and group communication, we present an integrated approach to provide security in hybrid wireless sensor networks.

Taking enterprise marketing as the research object, this paper discusses the construction and management of enterprise marketing network. First of all, it points out the necessity and importance of enterprise marketing network construction. Secondly, it discusses the key issues of enterprise marketing network management, including network security, network monitoring, network maintenance and so on. Finally, the paper puts forward some countermeasures and suggestions for the construction and management of enterprise marketing network, in order to provide some reference for the construction and management of enterprise marketing network.

In this paper, an on line Genetic Algorithm (GA) is proposed for estimating the cell loss probability (CLP) and the cell delay in real time. They are key parameters to many vital functions in the network such as call admission (CAC), bandwidth allocation, etc. However, the CLR and delay depend usually on many unknown and unpredictable traffic parameters such as input traffic correlations. In this paper, a novel Genetic Algorithm to predict the CLR and delay in different sized systems based on both a small amount of information from these systems. This algorithm is used with real time traffic measurement to maintain and design the ATM network.

ATM communication systems have introduced a number of new dimensioning problems, one being the evaluation of the loss probability for a shared buffer memory within a switch matrix. This is a problem of growing interest since shared buffer memory switches offer the best cell loss probability versus total buffer space provided, and thus are often the design of choice. ATM switches operate in a time slotted fashion: at the end of each slot, N cells will have been transmitted if all N servers have cells for transmission. If a server has no cell to transmit, it will produce an empty slot. Iliadis (1991) has presented a method for solving such a system based on the introduction of an N dimensional Markov chain. Schormans et al. (see Electronics Letters, vol.30, no.1, 1994) have presented a simplified algorithm for a fairly general arrival process. This paper considers certain problems in (shared) buffer dimensioning: calculation of the cell loss probability (CLP) for a 2/spl times/2 switching element, given any i/p loading; the effect, on such a shared buffer switching element, of allowing the applied traffic to approach the limit, i.e. during each time slot every input line will contain a new cell; and the relationship between the cell loss probability and the model of the routing strategy.

Call Admission Control (CAC) is one of the most important parts in Radio Resource Management of the wireless networks and it has a huge impact on the quality of service (QoS).Traditional CAC strategies focus on increasing the radio resource utility by decreasing the service blocking probabilities. In this paper, a new CAC scheme based on game theory is introduced to analyze the conflicts and rewards for different network operators. The game theoretic based CAC scheme contains two parts, utility function computation and a non-cooperative game between two networks to maximize their rewards. The proposed framework is preliminary and its objective is investigate the possibility that networks should be able to autonomously define policies for different parts of a coverage area depending on the priority of users and their requirements. In this approach, the two simulated WiMAX networks compete with each other for traffic units in overlapping coverage area and maximize their rewards. The proposed scheme is illustrated with the help of an example in which most of the traffic units lie close to one network as compared to the other network. Future work will present results of simulation studies for more detailed experiments.

Design and analysis of ATM networks in which sources are represented as fluid on/off is addressed. It is critical that cell loss rate as an important QOS measure be related to the call blocking, an important network design parameter, and this relation be used in link capacity sizing, call admission, and routing design. Recently, some research on the relation of cell loss and call blocking have appeared. However, they ignore buffering in the multiplexer. In this paper, it is shown that call blocking in a buffered ATM multiplexer behaves as an Erlang-B loss system. For analytic purposes system buffer is assumed infinite and transmission rate of the link (C) is assumed to be finite. Using past results on probability of cell loss and properties of Nearly Completely Decomposable Markov Chains, the aggregate cell loss when system is in different states is determined. It is shown that call blocking performance for a given link capacity is independent of the individual source parameters. An extended set of application of the results and an inverse problem is stated.

The stochastic fluid flow approach is applied to the analysis of the cell loss performance of an ATM multiplexer. The input traffic stream offered to the multiplexer is the superposition of heterogeneous on-off sources with independent and exponentially distributed on and off times. The focus is on the numerical investigation of the steady-state behavior of models involving very large state spaces. To this end, an efficient algorithm for the evaluation of tight upper and lower bounds of the cell loss probability is developed. The algorithm allows a significant reduction of the computational burden, while yielding a guaranteed overestimate of the error implied by the proposed approximation of the cell loss probability. Numerical results are presented both to assess the tightness of the proposed bounds and to gain insight into the behavior of heterogeneous traffic mixes. The main conclusion, from the multiplexer performance evaluation point of view, is that it is not convenient to mix very different traffic streams in a completely shared FIFO buffer, without some kind of control.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>