Performance modelling and evaluation of telecommunication systems

Queuing networks models are widely used as important tools for the performance modeling and evaluation of both computer systems and communication networks. Exact solutions are generally not attainable except for some special cases. Consequently, numerical techniques and analytic approximations are needed for the study of queuing networks with bursty traffic. This paper presents the performance modeling and evaluation of general packet radio service (GPRS) for wireless global system for mobile telecommunication (GSM) cells with bursty multi-class traffic under a partial sharing scheme (PSS). The model has been developed using a new powerful tool, MOSEL (Modeling, specification and evaluation language), which is based on numerical methods and the Petri-nets. The proposed model has been validated against simulation and those developed using maximum entry (ME), a well established methodology for approximate solutions. Numerical results demonstrate the credibility of our models.

The diversity of methodologies and applications in the literature for the traffic engineering, performance modelling and analysis of convergent multiservice heterogeneous networks attests to the breath and richness of recent research and developments towards the design and dimensioning of the next and future generation Internets. Heterogeneous Networks: Traffic Engineering, Performance Evaluation Studies and Tools describes recent advances in networks of diverse technology reflecting the state-of-the-art technology and research achievements in traffic engineering, performance evaluation studies and tools worldwide. Technical topics presented in the book include: Traffic Modelling and Characterisation Queueing and Interconnection Networks Performance Evaluation Studies TCP Performance Analysis Congestion Control Application Layer Multicast Numerical and Software Tools; This book contains recently extended research papers, which have their roots in the series of the HET-NETs International Working Conferences focusing on the Performance Modelling and Evaluation of Heterogeneous Networks under the auspices of the EU Networks of Excellence Euro-NGI and Euro-FGI. Heterogeneous Networks: Traffic Engineering, Performance Evaluation Studies and Tools is ideal for personnel in computer/communication industries as well as academic staff and master/research students in computer science, operational research, electrical engineering and telecommunication systems and the Internet. CACHE_VSTAMP

The situation of telecommunications systems is rapidly evolving towards a state characterized by the presence of a multitude of services integrated in a single network structure. In order to ease their integration, it is important to provide an unambiguous description of the organization, of the functionality, and of the relationships existing among services. Since it is not possible to completely foresee the situation of services in the future, the description should be modular, so that the task of adding new services to an existing environment is simplified. Formal description techniques are languages designed to handle such descriptions. Their goal is to produce correct and unambiguous specifications, understanding and modeling the system and the domain within which it operates. Their input is a set of required statements and a conceptual overview of the system. Their output is a formal representation that captures the functional behavior. On the other hand, the throughput of physical networks is constantly growing, reaching the order of Gbit/s. In the meantime, services needing high throughput, like multimedia conferencing systems are being designed, creating a need for flexible, high performance communication systems. An important feature of new high speed services is their increased need for guarantees. Therefore, the use of powerful performance modeling techniques becomes of prime importance. Their goal is to obtain some notion of how the system will perform under a given set of conditions. Performance evaluation theorists have long been using system specifications to make a heuristic model of the system and then an analysis of the model. When system specifications exist, the question arises whether a more direct path to performance analysis can be found. Our scope is to provide a methodology that fully and consistently integrates formal specification and performance evaluation. A problem is that many of the bottlenecks and impediments to smooth data flow have to do with implementation issues not directly dealt within the system specification itself. Therefore, prior to generating a performance model, the formal specification should be enhanced with the relevant non-functional information. It is essential to assure a smooth specification of the non-functional information. Thus, it is necessary to consistently add this information to the formal specification. Besides, the extended formal method should focus on conserving the semantics of the original one, and on providing a coherent extension of the semantics and syntax for the new concepts. Since all relevant required information is integrated within the formal extended representation, we provide a mapping technique that translates the extended formal representation into a performance modeling conserving the properties of the formal model. In parallel to the development of a performance model, the formal model can be validated and verified, and their implementation can be tested for conformance towards the original formal model. Finally, the performance modelling is implemented in a programming language, and then simulated. The results from simulation can be reused as inputs for the optimization of the formal specification (functional optimization) or the extended formal model (design optimization). To sum up, the goal of this work is to: Define extensions to current formal methods that allow to enhance the formal specification with performance modeling related information. Develop a method to translate the extended formal specification into a performance modeling. Develop rules and guidelines to automatically implement the performance modeling for the purpose of a performance evaluation (we use the commercial tool Opnet). Develop a consistent and coherent methodology for the integration of performance modeling and formal specification.

Summary form only given. Telecommunications systems were among the first to use modeling and analysis to improve designs. Since those early days, researchers have made many advances in the technology and tools. Performance models have been successfully applied to a variety of other computer systems design problems. When we consider the current state of the art and state of the practice, are we satisfied with the results? What areas need improvement? We explore these questions by first considering some of the important research issues of the past. Which have been resolved and which need further work? Have advances in technology mitigated some of the issues while exacerbating others? Next we consider the proactive application of performance models during system design to resolve problems before they occur. How extensive is this practice? How successful is it? What are the barriers to more widespread use and what can we do about it?.

This volume covers recent developments in the design, operation, and management of mobile telecommunication and computer systems. Uncertainty regarding loading and system parameters leads to challenging optimization and robustness issues. Stochastic modeling combined with optimization theory ensures the optimum end-to-end performance of telecommunication or computer network systems. In view of the diverse design options possible, supporting models have many adjustable parameters and choosing the best set for a particular performance objective is delicate and time-consuming. An optimization based approach determines the optimal possible allocation for these parameters. Researchers and graduate students working at the interface of telecommunications and operations research will benefit from this book. Due to the practical approach, this book will alsoserve as areference tool for scientists and engineers in telecommunication and computer networks who depend upon optimization.

The use of wireless communications networks has gained phenomenal momentum both in the business and individual-user sectors. As a consequence of the increasing reliance of businesses on such networks, service disruption due to network facility failures can cause severe economic impact on the associated business. Hence service survivability-i.e., providing continued service in the midst of network failures becomes an important feature for network providers to incorporate within their network. In this work, we propose appropriate self-healing mechanisms that can be used by network providers/engineers to provide automatic service restoration (hence service survivability) in the event of network facility failures in the wireless networks of today. In particular, our contribution is as follows. We propose appropriate (cost-performance- and complexity-sensitive) self-healing mechanisms that can be used both in the currently deployed GSM-based and the rapidly emerging GPRS-based wireless networks to provide service survivability. We then perform modeling and simulation of portions of the proposed self-healing mechanisms and analyze the performance of the proposed self-healing mechanism in the core network portion of a GSM/GPRS-based system. Our simulations not only help to demonstrate the importance of simulation-based studies towards understanding, modeling and analyzing the performance of the proposed self healing mechanisms but also help provide useful insights into the potential of the proposed self-healing mechanisms.

DNS Servers significantly play a vital role in Internet and Intranet environments. It translates human-friendly names into IP addresses and vice versa. However, propagation processing of any change in DNS Server takes hours and days for its full global-wide implementation in both the versions of IP addressing scheme. This is the age of fast communication where bulk of data communication occurs globally in terms of tera, peta or exa bytes etc., where trends of developing traditional desktop software changing into dynamic web-based applications, where computer networks are emerging into telecommunication networks, where wired and wireless networks are transforming into network mobility, where traditional data communication is emerging into highspeed digital audio/video streaming using video conferencing IP data streaming techniques; it sounds contemptible and abominable for waiting hours for DNS information proliferation for a single minor change. In this paper, an authoritative response from a non-authoritative DNS server is proposed and tested, through which not only request time out has been reduced but also DNS resolution time dropped to around 50% in comparison with the existing DNS resolution process.

Computer simulation is becoming increasingly popular among computer network researchers for performance modeling and evaluation of computer and telecommunication networks. This popularity is due to the availability of various sophisticated and powerful simulators, and also because of the flexibility in model construction and validation offered by simulation. While various network simulators (both open source and commercial) exist for modeling and performance evaluation of communication networks, OPNET is becoming popular network simulator as the package is available to academic institutions at no cost, especially OPNET IT Guru. This chapter aims to provide a tutorial on OPNET focusing on the simulation and performance modeling of IEEE 802.11 wireless local area networks (WLANs). Results obtained show that OPNET provides credible simulation results close to a real system.

The complexity of computer systems, networks and applications, as well as the advancements in computer technology, continue to grow at a rapid pace. Mathematical analysis, modeling and optimization have been playing, and continue to play, an important role in research studies to investigate fundamental issues and trade-offs at the core of performance problems in the design and implementation of complex computer systems, networks and applications. On June 20, 2014, the 16th Workshop on MAthematical performance Modeling and Analysis (MAMA 2014) was held in Austin TX, USA, sponsored by ACM SIGMETRICS, and held in conjunction with SIGMETRICS 2014. This workshop seeks to bring together researchers working on the mathematical, methodological and theoretical aspects of performance analysis, modeling and optimization. It is intended to provide a forum at SIGMETRICS conferences for talks on early research in the more mathematical areas of computer performance analysis. These talks tend to be based on very recent research results (including work in progress) or on new research results that will be otherwise submitted only to a journal (or recently have been submitted to a journal). Thus, part of the goal is to complement and supplement the SIGMETRICS Conference program with such talks without removing any theoretical contributions from the main technical program. Furthermore, we continue to experience the desired result of having abstracts from previous MAMA workshops appear as full papers in the main program of subsequent SIGMETRICS and related conferences. All submissions were reviewed by at least 4 members of the program committee, from which a total of 13 were selected for presentation at the MAMA 2014 workshop. This special issue of Performance Evaluation Review includes extended abstracts relating to these presentations (arranged in the order of their presentation), which cover a wide range of topics in the area of mathematical performance analysis, modeling and optimization. The study of Gelenbe examines the backlog of energy and of data packets in a sensor node that harvests energy, computing the properties of energy and data backlogs and discussing system stability. Meyfroyt derives asymptotic results for the coverage ratio under a specific class of spatial stochastic models (Cooperative Sequential Adsorption) and investigates the scalability of the Trickle communication protocol algorithm. The study of Tune and Roughan applies the principle of maximum entropy to develop fast traffic matrix synthesis models, with the future goal of developing realistic spatio-temporal traffic matrices. Bradonjić et al. compare and contrast the capacity, congestion and reliability requirements for alternative connectivity models of large-scale data centers relative to fat trees. The study of Rochman et al. considers the problem of resource placement in network applications, based on a largescale service faced with regionally distributed demands for various resources in cloud computing. Xie and Lui investigate the design and analysis of a rating system and a mechanism to encourage users to participate in crowdsourcing and to incentivize workers to develop high-quality solutions. The study of Asadi et al. formulates a general problem for the joint per-user mode selection, connection activation and resource scheduling of connections using both LTE and WiFi resources within the context of device-todevice communications. Zheng and Tan consider a nonconvex joint rate and power control optimization to achieve egalitarian fairness (max-min weighted fairness) in wireless networks, exploiting the nonlinear Perron-Frobenius theory and nonnegative matrix theory. The study of Goldberg et al. derives an asymptotically optimal control policy for a stochastic capacity problem of dynamically matching supply resources and uncertain demand, based on connections with lost-sales inventory models. Ghaderi et al. investigate a dynamic stochastic bin packing problem, analyzing the fluid limits of the system under an asymptotic best-fit algorithm and showing it asymptotically minimizes the number of servers used in steady state. The study of Tizghadam and Leon-Garcia examines the impact of overlaying or removing a subgraph on the Moore-Penrose inverse of the Laplacian matrix of an existing network topology and proposes an iterative method to find key performance measures. Miyazawa considers a two-node generalized Jackson network in a phase-type setting as a special case of a Markov-modulated twodimensional reflecting random walk and analyzes the tail asymptotics for this reflecting process. The study of Squillante et al. investigates improvement in scalability of search in networks through the use of multiple random walks, deriving bounds on the hitting time to a set of nodes and on various performance metrics.

Computer Network Integrated Manufacturing: Performance Evaluation Using Distributed Simulation

The wireless mesh networks (WMNs) have become one of the popular technologies of the wireless network utilization. WMN provides reliable and scalable wireless network because of its features such as dynamic self-organizing, self-configuring, Self-managing and self-healing. Routing protocols play an essential role in finding and establishing an active route from a source to a destination in WMNs. This article focuses on the performance evaluation and comparison of some routing protocols commonly used in WMNs for VoIP application: AODV, DSR, OLSR and TORA has been investigated over client Wireless Mesh Networks based on OPNET simulation in a different network sizes and mobility. This article presents a background of some designs and solutions based on an elaborated simulation investigation. The performance comparisons are carried out with regard to the node variation in network sizing and mobility. Based on the empirical outputs, the authors suggested that to utilize a specific routing protocol in certain situations.

The 8th International Workshop on Performance Modeling, Evaluation, and Optimization of Ubiquitous Computing and Networked Systems (PMEO-UCNS'09)

Performance Modeling and Evaluation of Web Server Systems with Proxy Caching

Welcome to PMEO-UCNS'10! This is the 9 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> International Workshop on Performance Modeling, Evaluation, and Optimization of Ubiquitous Computing and Networked Systems is being held in conjunction with IPDPS'10.

The paper presents a performance evaluation and resource management of hierarchical MACRO-/MICRO cellular networks using the new Modeling and Evaluation Language (MOSEL-2). MOSEL-2 with new constructs has the ability to find the performance and reliability modeling and evaluation of systems with exponential and non-exponential distributions. A MACRO/MICRO cell structure is solved numerically and mathematically in this paper to handle the handoff calls. Additionally, a simulation program is written to validate these results. In order to reduce the loss probability, a guard channels are introduced at the MICRO cell and channel reservation at the MACRO cell. Additionally, the concept of queuing is introduced where there is a possibility for the handoff calls from both MACRO and MICRO layers to be queued when all the resources are occupied. MOSEL-2 is used to find the numerical solution for this problem with both exponential and general exponential (GE) distribution. The performance analysis show the efficiency of the proposed scheme to manage the handoff calls and the ability of the suggested scheme to reduce the blocking probability of handover calls and the loss probability as the main objective is to block the new connection rather than terminating the ongoing connection as well as balancing the load all over the whole network. It is shown in this paper that there are a set of important factors that affect the performance, such as: reservation policy, channel allocation, handover ratio, capacity of the queue and the variation of the inter-arrival times. These factors are discussed via some important performance measures, such as: new call blocking probability, blocking probability of handover calls, loss probability, utilization and the average delay of the queue.