Synchronizing asynchronous bounded delay networks

An efficient way to synchronize an asynchronous network with a bounded delay message delivery is presented. Two types of synchronization algorithm are presented. Both types require an initializing phase that costs |E| messages (where |E| is the number of links). The first requires an additional bit in every message and increases the time complexity by a factor of 2. The second does not require any additional bits but increases the time complexity by a factor of 3. How to overcome differences in nodal timer rates is explained     

Satellite systems for personal communication networks

The paper addresses some issues related to Satellite Personal Communication Networks (S‐PCNs). The role of satellite communications in that scenario is discussed, and some characteristics of S‐PCNs are identified. In addition, the problem of the integration of S‐PCNs with the Universal Mobile Telecommunication System (UMTS) is considered. In this respect an original methodology for accomplishing such integration is proposed; such methodology aims at avoiding complex protocol conversions at the interfaces between the terrestrial and the satellite segment. The paper is partly based upon the work performed by the authors in the framework of the European Community INSURED Project “INtegrated Satellite UMTS Real Environment Demonstrator”. This revised version was published online in June 2006 with corrections to the Cover Date.     

Quantum communication for wireless wide-area networks

In this paper, a quantum routing mechanism is proposed to teleport a quantum state from one quantum device to another wirelessly even though these two devices do not share EPR pairs mutually. This results in the proposed quantum routing mechanism that can be used to construct the quantum wireless networks. In terms of time complexity, the proposed mechanism transports a quantum bit in time almost the same as the quantum teleportation does regardless of the number of hops between the source and destination. From this point of view, the quantum routing mechanism is close to optimal in data transmission time. In addition, in order to realize the wireless communication in the quantum domain, a hierarchical network architecture and its corresponding communication protocol are developed. Based on these network components, a scalable quantum wireless communication can be achieved.     

Traffic models for wireless communication networks

Introduces a deterministic fluid model and two stochastic traffic models for wireless networks. The setting is a highway with multiple entrances and exits. Vehicles are classified as calling or noncalling, depending upon whether or not they have calls in progress. The main interest is in the calling vehicles; but noncalling vehicles are important because they can become calling vehicles if they initiate (place or receive) a call. The deterministic model ignores the behavior of individual vehicles and treats them as a continuous fluid, whereas the stochastic traffic models consider the random behavior of each vehicle. However, all three models use the same two coupled partial differential equations (PDEs) or ordinary differential equations (ODEs) to describe the evolution of the system. The call density and call handoff rate (or their expected values in the stochastic models) are readily computable by solving these equations. Since no capacity constraints are imposed in the models, these computed quantities can be regarded as offered traffic loads. The models complement each other, because the fluid model can be extended to include additional features such as capacity constraints and the interdependence between velocity and vehicular density, while the stochastic traffic model can provide probability distributions. Numerical examples are presented to illustrate how the models can be used to investigate various aspects of time and space dynamics in wireless networks     

Multiwavelength lightwave networks for computer communication

The different approaches being considered to build high-capacity lightwave networks are described. Two kinds of lightwave network architectures are examined: broadcast-and-select networks and wavelength-routing networks. A comparison of the two shows that broadcast-and-select networks may be more suitable for local area networks (LANs) and metropolitan area networks (MANs), while wavelength-routing networks are suitable for wide area networks (WANs). The overall network may then be a combination of broadcast subnets interconnected by a point-to-point wavelength-routing network     

New radio networks for tactical communication

A packet-switched radio system designed and developed for the Norwegian Army is presented. In particular, the development of an overall network concept, the network and access protocols, and the routing strategy are examined. Network synchronization and radio process protocols are discussed, and simulation results are given. A radio design allowing integration of electronic countermeasures (ECM) protected data and voice channels is presented     

Network coding for wireless communication networks

This special issue includes a collection of 19 outstanding research papers which cover a diversity of topics on the application of network coding in wireless communication networks.     

Designing communication subsystems for high-speed networks

Is shown that system structure and implementation of a communication subsystem are vital elements in high-throughput protocol implementation. A well-structured and carefully implemented subsystem can exploit high-speed transmission links and preserve their speed up to the application. The issues of memory management and organization are presented as examples. Support for data movement and processing overlap, and intelligent DMA, two alternatives for the communication subsystem to achieve higher performance and scale to higher-speed links, are discussed     

Developing technologies for personal communication networks

The author reviews the technologies needed to meet the demands of the personal communication network (PCN) service, and gives the reasons why the three successful PCN applicants stated their preference for Groupe Speciale Mobile, (GSM) as the basis for PCN. Then the author discusses how, based on GSM, the DCS1800 standard (digital communication system at 1800 MHz) was elaborated by ETSI to meet PCN requirements     

Coalitional game theory for communication networks

In this tutorial, we provided a comprehensive overview of coalitional game theory, and its usage in wireless and communication networks. For this purpose, we introduced a novel classification of coalitional games by grouping the sparse literature into three distinct classes of games: canonical coalitional games, coalition formation games, and coalitional graph games. For each class, we explained in details the fundamental properties, discussed the main solution concepts, and provided an in-depth analysis of the methodologies and approaches for using these games in both game theory and communication applications. The presented applications have been carefully selected from a broad range of areas spanning a diverse number of research problems. The tutorial also sheds light on future opportunities for using the strong analytical tool of coalitional games in a number of applications. In a nutshell, this article fills a void in existing communications literature, by providing a novel tutorial on applying coalitional game theory in communication networks through comprehensive theory and technical details as well as through practical examples drawn from both game theory and communication application.     

Exact admission control for networks with a bounded delay service

To support the requirements for the transmission of continuous media, such as audio and video, multiservice packet-switching networks must provide service guarantees to connections, including guarantees on throughput, network delays, and network delay variations. For the most demanding applications, the network must offer a service which provides deterministically bounded delay guarantees, referred to as “bounded delay service.” The admission control functions in a network with a bounded delay service require `schedulability conditions' that detect violations of delay guarantees in a network switch. Exact schedulability conditions are presented for three packet scheduling methods: earliest-deadline-first (EDF), static-priority (SP), and a novel scheduling method, referred to as rotating-priority-queues (RPQ). By characterizing the worst-case traffic with general subadditive functions, the presented schedulability conditions can be applied to a large class of traffic models. Examples, which include actual MPEG video traces, are presented to demonstrate the trade-offs involved in selecting a packet scheduling method for a bounded delay service     

On bounded real lemma in multivariable networks

The bounded real lemma for multivariable networks is interpreted in state-space terms. This lemma is useful in the synthesis of networks having lumped transmission line elements.     

Mobile responder communication networks for public safety

This article proposes a paradigm shift from the prevailing public safety model of disparate, agency-owned and -operated Land Mobile Radio networks to Mobile Responder Communication Networks (MRCNs) that are created by unifying communications resources and are shared across cooperating public safety agencies to provide local, regional, or national service. MRCNs use a common IP-based core network employing service-intelligent session control to bridge networks based on LMR and commercial wireless access technologies, thus allowing the support of emerging IP-based multimedia services, high data rate access, and mission-critical tactical group voice and interoperable communications during emergency responses.     

提高通信网络可靠性的方法探析

从产品的可靠性定义出发,通过对通信网络可靠性的分析得出了影响通信网络可靠性的因素。从提高节点／设备的可靠性、优化拓扑结构、使用网络保护与恢复技术、使用差错控制技术等几个方面详细介绍了提高通信网络可靠性的方法和需要注意的问题,并简要说明了其它的方法。最后,指出这些方法已经运用于工程实践并被证明切实有效。     

Mobile power management for wireless communication networks

For fixed quality-of-service constraints and varying channel interference, how should a mobile node in a wireless network adjust its transmitter power so that energy consumption is minimized? Several transmission schemes are considered, and optimal solutions are obtained for channels with stationary, extraneous interference. A simple dynamic power management algorithm based on these solutions is developed. The algorithm is tested by a series of simulations, including the extraneous-interference case and the more general case where multiple, mutually interfering transmitters operate in a therefore highly responsive interference environment. Power management is compared with conventional power control for models based on FDMA/TDMA and CDMA cellular networks. Results show improved network capacity and stability in addition to substantially improved battery life at the mobile terminals.     

High-speed nondirective optical communication for wireless networks

The primary obstacles to high-speed communication, namely, shot noise from ambient light, high-capacitance photodiodes and multipath dispersion, are reviewed, and ways to counter them are demonstrated for a prototypical infrared system. The discussion is limited to the physical-layer issues involved in the design of a single high-speed optical link. The focus is on the downlink (from base station to portable), which is a more challenging problem technically than the uplink for two reasons. First, the complexity of the portable receiver is much more constrained than that of the base station, due to power consumption and cost restrictions. Second, the downlink data rates are likely to be much higher than the uplink rates, because downlink communication will include downloading large executable files and possibly video services, whereas uplink communication will be used for transferring working files and keyboard commands which tend to be much smaller     

Schemes for fault identification in communication networks

A single fault in a large communication network may result in a large number of fault indications (alarms) making the isolation of the primary source of failure a difficult task. The problem becomes worse in cases of multiple faults. In this paper we present an approach for modelling the problem of fault diagnosis. We propose a graph based network model that takes into account the dependencies among the different objects in the telecommunication environment and a novel approach to estimate the domain of an alarm. Based on that model, we design an algorithm for fault diagnosis and analyze its performance with respect to the accuracy of the fault hypotheses it provides. We also propose and analyze a fault diagnosis algorithm suitable for systems for which an independent failure assumption is valid. Finally, we examine the importance of the information of dependency between objects for the fault diagnosis process