Communication Network Architecture Research Articles

A WDM-based PCN architecture

This paper proposes personal communication network (PCN) architecture based on wavelength-division multiplexing (WDM). By employing the broadcast nature of the WDM star couplers, the proposed architecture furnishes a very simple and fast hand off procedure. To overcome the wavelength offset conflict problem that might happen in this architecture when mobile terminal roams to a neighboring cell, a wavelength assignment scheme is also proposed. This scheme assigns the wavelength channels to the established connections, including the roaming ones, efficiently so that the wavelength offset conflict rate is kept as low as possible. Simulation results show that compared to the random assignment strategy, the proposed scheme furnishes a much better offset conflict rate.

A User-Focused Security Service Architecture for Communication Networks

Summary This paper discusses how to include security into existing communication services in a way that increases the users' trust. Throughout this paper, we discuss a security architecture that enables secure communication services to both satisfy the users' security needs and protect investments into existing network infrastructure. Adding security implies penalties in cost, quality of service, or usage pattern. Thus, our proposal aims at optional security services that are activated by users on demand. We accomplish this by exploiting existing service interfaces to plug-in security services call-by-call. Communication services offer many benefits and become essential in people's business and private lives. Therefore, architects of communication networks need to address the users' security requirements more carefully than in the past. By including open security interfaces throughout the communication system design, users gain flexibility in choosing those security solutions that satisfy their requirements most efficiently. As the whole is no more secure than the weakest of its parts, separating security sensitive functions from highly complex communication functions promotes security. Additionally, this approach leads to security services that are mostly independent of the communication services they protect. Thus, these security services can be universally used and implemented in highly secure runtime environments. These portable and secure runtime environments can accompany the users wherever they go.

Potential metering communication services using the public Internet

The Internet was born approximately 20 years ago out of a project to integrate a US Defence Department Network called ARPAnet. This integration involved radio satellite voice and data networks. The Internet has completely revolutionised public communication networks. The concept of using the Internet for a metering communications service is proposed. The use of the Internet for a range of customer services in the residential and industrial area is also detailed. The Internet provides the potential for integrating many thousand of homes into a wide area metering communications network (WAMCN) architecture. The potential characteristics of this type of communication architecture are established for efficient transport of data services.

CIMS network protocol and its net models

Computer communication network architectures for CIMS are based on the OSI Reference Model. In this paper, CIMS network protocol model is set up on the basis of the corresponding service model. Then the authors present a formal specification of transport protocols by using an extended Predicate/Transition net system that is briefly introduced in the third part. Finally, the general methods for the Petri nets based formal specification of CISM network protocols are outlined.

Stochastic geometry and architecture of communication networks

This paper proposes a new approach for communication networks planning based on stochastic geometry. We first summarize the state of the art in this domain, together with its economic implications, before sketching the main expectations of the proposed method. The main probabilistic tools are point processes and stochastic geometry. We show how several performance evaluation and optimization problems within this framework can actually be posed and solved by computing the mathematical expectation of certain functionals of point processes. We mainly analyze models based on Poisson point processes, for which analytical formulae can often be obtained, although more complex models can also be analyzed, for instance via simulation.

Dynamic mobile user location update for wireless PCS networks

The basic architecture of a personal communication network consists of a wireline network and mobile terminals. Each mobile terminal communicates with the wireline network through a nearby base station. In order to route incoming calls to a destination mobile terminal, the network must keep track of the location of each mobile terminal from time to time. This is achieved by location update such that each mobile terminal reports its current location to the network at specific time points. When an incoming call arrives, the network will page the mobile terminal starting from the last updated location. A trade-off, therefore, exists between the frequency of location update and the number of locations paged in order to track down the mobile terminal. This paper introduces a location update policy which minimizes the cost of mobile terminal location tracking. A mobile terminal dynamically determines when to update after moving to a new cell based on its mobility pattern and the incoming call arrival probability. The performance of this scheme is close to that of the optimal policy reported earlier. However, the processing time requirement of this scheme is very low. The minimal computation required by this scheme enables its usage in mobile terminals which has limited energy supply and computational power.

A recursive variance-reduction algorithm for estimating communication-network reliability

In evaluating the capacity of a communication network architecture to resist possible faults of some of its components, several reliability metrics are used. This paper considers the /spl Kscr/-terminal unreliability measure. The exact evaluation of this parameter is, in general, very costly since it is in the NP-hard family. An alternative to exact evaluation is to estimate it using Monte Carlo simulation. For highly reliable networks, the crude Monte Carlo technique is prohibitively expensive; thus variance reduction techniques must be used. We propose a recursive variance-reduction Monte-Carlo scheme (RVR-MC) specifically designed for this problem, RVR-MC is recursive, changing the original problem into the unreliability evaluation problem for smaller networks. When all resulting systems are either up or down independently of components state, the process terminates. Simulation results are given for a well-known test topology. The speedups obtained by RVR-MC with respect to crude Monte Carlo are calculated for various values of component unreliability. These results are compared to previously published results for five other methods (bounds, sequential construction, dagger sampling, failure sets, and merge process) showing the value of RVR-MC.

ATM-based transport architecture for multiservices wireless personal communication networks

This paper presents an ATM-based transport architecture for next-generation multiservices personal communication networks (PCN). Such multimedia integrated services wireless networks are motivated by an anticipated demand for wireless extensions to future broadband networks. An ATM compatible wireless network concept capable of supporting a mix of broadband ISDN services including constant bit-rate (CBR), variable bit-rate (VBR), and packet data transport is explored from an architectural viewpoint. The proposed system uses a hierarchical ATM switching network for interconnection of PCN microcells, each of which is serviced by high-speed, shared-access radio links based on ATM-compatible cell, relay principles. Design issues related to the physical (modulation), media access control (MAC), and data-link layers of the ATM-based radio link are discussed, and preliminary technical approaches are identified in each case. An example multiservice dynamic reservation (MDR) TDMA media access protocol is then considered in further detail, and simulation results are presented for an example voice/data scenario with a proportion of time-critical (i.e., multimedia) packet data. Time-of-expiry (TOE) based queue service disciplines are also investigated as a mechanism for improving the quality-of-service (QoS) in this scenario. >

Real-time communication in packet-switched networks

The dramatically increased bandwidths and processing capabilities of future high-speed networks make possible many distributed real-time applications, such as sensor-based applications and multimedia services. Since these applications will have traffic characteristics and performance requirements that differ dramatically from those of current data-oriented applications, new communication network architectures, and protocols will be required. In this paper we discuss the performance requirements and traffic characteristics of various real-time applications, survey recent developments in the areas of network architecture and protocols for supporting real-time services, and develop frameworks in which these, and future, research efforts can be considered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Reliability Evaluation of Communication Networks

In the evaluation of the capacity of a communication network architecture to resist to the possible faults of some of its components, several reliability metrics are currently used. The evaluation of these metrics is in general a very costly task since most of them are, as algorithmic problems, classed in the NP-hard family. As a consequence, many different techniques have been proposed to solve them. We discuss here a promising class of methods called “factorization” and some of the implementation issues. An alternative approach to these exact techniques is to perform statistical estimations using a Monte Carlo simulation. It allows to deal with larger networks (having, say, hundreds of components) if the user accepts probabilistic answers. In the case of highly reliable networks, the standard Monte Carlo technique is also prohibitively expensive and variance reduction techniques must be used. We propose here a new Monte Carlo algorithm specifically designed to this context. For both approaches, exact and simulation algorithms, numerical results are provided allowing a comparison and giving an idea of the performances that can be expected.

TOPNET: a tool for the visual simulation of communication networks

TOPNET is a software package for the simulation of communication networks that is being developed with the aim of exploiting as much as possible the visual aspects of a simulation experiment. The communication network topology and architecture are described by drawings, the system dynamics are represented with a class of timed Petri nets, the simulation experiment is controlled through menus and buttons activated with a mouse, and results are graphically displayed on the screen. With the help of an example, the main characteristics of the user interface and the internal architecture of TOPNET are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Control architecture for next-generation communication networks based on distributed databases

Intelligent routing control is defined as the process in which the network interrogates the databases containing the relationships between logical numbers, such as personal or information identifiers, and physical addresses in the transport network to find the terminal having the information required to process a user request. The routing control system presented uses distributed databases, each of which manages a switching system and all of which are connected through high-speed signalling networks separate from the transport network. If the requested physical address cannot be found in one database, search requests are distributed at the same time to all other databases. For up to 100 million subscribers, the routing control system can find a physical address within 1 s when each database uses ten memories accessed at 200 ns with an interdatabase linkage speed of 14 Mb/s. >

Performance of Double-Tier Access-Control Schemes Using a Polling Backbone for Metropolitan and Interconnected Communication Networks

We consider a double-tier communication network architecture for metropolitan area and packet radio networks for controlling the access of network terminals into a single shared broadcast channel. Terminals are organized into local groups in accordance with their geographical proximity or other criteria. Each local group can be associated with a primary station. The latter can serve as an unbuffered repeater for terminal transmissions unto the multiple-access channel. A polling policy is used by the primary stations to gain access into the shared communications backbone. Once a primary station is provided access into the channel, it initiates a local access control procedure. Message delay performance results and bounds are obtained for general reservation local-access procedures. In particular, we analyze and present performance results for a polling/tree-random-access procedure which can be effectively used for many packet radio and cellular digital radio networks, as well as for a polling/positionalpriority scheme for CATV and fiber-optic based networks.

Designing a new architecture for packet switching communication networks

Designing a new architecture for packet switching communication networks

Data communications: The implications of communication systems for protocol design

The construction of a communication network architecture, specifying protocols by which systems communicate, is a complex art. Much has been written about the optimal protocols for theoretical models of systems. This paper points out that protocol design must depend on the “nuts and bolts” of the systems which implement the protocols. Numerous examples are provided to support this thesis. The paper also briefly discusses other issues that influence protocol design and draws lessons for standards activities.

Helping computers communicate: The Open Systems Interconnection model promises compatibility for a variety of computer systems, although not all its functions are yet defined

The possibilities opened up by the Open Systems Interconnection (OSI) model are discussed. It is noted that many of the protocols to implement OSI are now complete, and manufacturers offer products to implement some of the standards. The International Organization for Standardization will continue to expand the functions covered by OSI as new communications network architectures and technologies emerge. Each of the seven layers making up the model is described. Prospects for the model's success are then surveyed.

Integrated Broad-Band Communication Systems in Belgium

Belgian politicians, the National Telecommunications Administration (RTT), and the telecommunication industry in general fully realize the major economic, industrial, and social importance of an advanced telecommunications infrastructure for the future of the country. A national effort is therefore underway. This paper describes the specific Belgian telecommunications environment, its development towards an ISDN infrastructure, and evolution towards the integration of telecommunication and distribution services into a uniform broad-band communication network. The present network structures for both telecommunication and distribution services are briefly discussed in this paper. Furthermore, plans and experiments in the area of ISDN are also described. Explanations related to the basic concepts of a national integrated broad-band communication network and possible architectures for a demonstration project are given.

Performance of globally distributed networks

In the design and implementation of computer networks one must be concerned with their overall performance and the efficiency of the communication mechanisms chosen. Performance is a major issue in the architecture, implementation, and installation of a computer communication network. The architectural design always involves many cost/performance tradeoffs. Once implemented, one must verify the performance of the network and locate bottlenecks in the structure. Configuration and installation of a network involves the selection of a topology and communication components, channels and nodes of appropriate capacity, satisfying performance requirements. This panel will focus on performance issues involved in the efficient design, implementation, and installation of globally distributed computer communication networks. Discussions will include cost/performance tradeoffs of alternative network architecture structures, methods used to measure and isolate implementation performance problems, and configuration tools to select network components of proper capacity. The panel members have all been involved in one or more performance issues related to the architecture, implementation, and/or configuration of the major networks they represent. They will describe their experiences relating to performance issues in these areas. Methodologies and examples will be chosen from these networks in current use. There will be time at the end of the session for questions to the panel.

Preface to the Special Issue

This Special Issue deals with the way computer networks are put together. There are various topics that are covered in this Special Issue. They consist of the systematic portrayal of the way communication network architectures are put together and conclude with an tip-to-date sampling of one of the most active. and exciting research areas in the protocol field today, verifying and directly implementing protocols from a formal specification. Throughout our discussion of the various architectures and protocols, the authors have been at pains to provide a readable description that is both tutorial and, within limits, encyclopedic.

DCNA Higher Level Protocols

This paper explains a philosophy for modeling the higher level communication functions into a network architecture for heterogeneous computer networks called Data Communication Network Architecture (DCNA), the logical structure of the architecture, and several protocols based on it. To specify higher level protocols among computers of different types, DCNA defines a logical model of a computer network consisting of three submodels: the basic model, the logical network model, and the virtual network model. The basic model represents a logical view of the network resources, e.g., processing power, files, data bases, I/O devices, and a layered structure for the basic mechanisms for accessing such resources, which incorporate the concept of sublevels as well as levels. The logical network model describes the mechanisms for unified management of network resources. The virtual network model describes the mechanisms for using network resources. The. common use of network resources, by several sets of interrelated applications is made easier by treating the logical network and the virtual network separately. These models form the basis for the stipulation of higher level protocols, such as network management protocols, message transfer protocols, virtual terminal protocols, and virtual file system protocols.