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Communication Services (communication + services)
Selected AbstractsPerformance analysis of microcell/macrocell with reuse partitioning in TDMA-based cellular systemsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 9 2008Jane Y. Yu Abstract System capacity and grade of service (GoS) are both important for the rapid growth of cellular communication services. In this paper, we propose a two-tier TDMA-based cellular system with macrocell overlaid on microcell clusters by implementing fixed channel assignment (FCA) scheme and fixed reuse partitioning (FRP) scheme in microcell layer and macrocell layer, respectively, named FCA,FRP overlay scheme. Improvement can be achieved in both system capacity and GoS. Theoretical analysis based on the overlay scheme without overflow and with overflow is first presented. It shows that the simulation results are agreed with the analytical results. Then, simulation results, obtained from the overlay scheme with and without overflow, show that the performance in terms of the call blocking probability, the call dropping probability and system capacity of such a system can be greatly improved compared with a conventional one-tier cellular system deployed with FCA or FRP scheme. Copyright © 2008 John Wiley & Sons, Ltd. [source] Practical performance of digital cellular system in mass rapid transit environmentsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2005Y. P. ZhangArticle first published online: 13 DEC 200 Abstract Leaky coaxial cables have found applications in the creation of network infrastructures for mobile and personal communication services in underground and enclosed spaces. A digital cellular system based on the GSM 900 standard and using radiated mode leaky coaxial cables has been implemented in an underground mass rapid transit environment. This paper presents the practical performance evaluation of the system. First, we start with a brief introduction of a radiated mode leaky coaxial cable and the digital cellular system GSM 900, and then we move into a full description of the measurement campaign; next we focus on an analysis of the measured performance data about received signal level, received signal quality, speech quality index and grade of service. The results show that the system performance is generally good; however, the poor system performance often occurs at the terminals of the leaky coaxial cable. In addition, it is found that the system performance is highly correlated with the density of train passenger. The higher train passenger density degrades the system performance. Copyright © 2004 John Wiley & Sons, Ltd. [source] A survey on mobile satellite systemsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2010Paolo Chini Abstract Satellite systems represent a significant solution to provide communication services to mobile users in under-populated regions, in emergency areas, on planes, trains, and ships. In all these cases, satellite systems have unique capabilities in terms of robustness, wide area coverage, and broadcast/multicast capabilities. This paper surveys current mobile satellite networks and services from different standpoints, encompassing research issues, recent standardization advances (e.g. mobile extension for DVB-S2/-RCS, DVB-SH) and some operational systems (e.g. Globalstar, Inmarsat BGAN, Iridium, and Thuraya). The last part of this paper is devoted to qualitative and quantitative comparisons of the different mobile satellite systems to understand their characteristics in terms of services, capacity, resource utilization efficiency, and user mobility degree.Copyright © 2009 John Wiley & Sons, Ltd. [source] Analyzing GPS signals to investigate path diversity effects of non-geostationary orbit satellite communication systemsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2002Hsin-Piao Lin Abstract The concept behind path diversity is that a user who can access several satellites simultaneously will be able to communicate more effectively than a user who could only access one. The success of this method depends on the environment, the satellite constellation, and diversity combining technology. This paper explores the path diversity effects of non-geostationary orbit (NGO) satellite personal communication services, for different degrees of user mobility, under various scenarios, using the constellation of the global positioning system (GPS). Measurements are taken near downtown Taipei. Three types of mobilities (fixed-point, pedestrian, and vehicular) are examined, and the switch diversity and maximum ratio combining method are applied to determine the path diversity gain and calculate bit error probability. The error probability performance of applying diversity schemes in coherent binary phase shift keying (BPSK) and non-coherent differential phase shift keying (DPSK) modulations over Rician fading channels are also analysed and evaluated by using the characteristic function method. The results show that fading can be significantly reduced and diversity greatly increased. A significant diversity gain and improvement in bit error rate (BER) can be expected in all cases by simply applying switch diversity scheme. Besides, for the maximum ratio combining method, the results imply that summing two satellite signals suffices to increase diversity and improve the bit error rate performance. Copyright © 2002 John Wiley & Sons, Ltd. [source] Multimedia satellite communications experiments to the international space stationINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2002Carlo Matarasso Abstract In the present concept of the International Space Station ISS, it is planned to provide the communication services between the European Columbus module of the ISS and the ground equipment via the TDRS (tracking and data relay satellite) network provided by the American NASA (National Aeronautics and Space Agency). Especially because of its low uplink data rate, an unacceptable limitation of the communication services with Columbus is to be expected. In order to investigate possible improvements to this situation, the MEDIS proposal studies the feasibility of a 150 Mbps full duplex communication system to the Columbus Module on via two MEO satellites. A mixed topology with optical inter satellite links and Ka-band up/down-links shall be employed. Also possible liaisons with the Artemis mission will be considered. The MEDIS project is a collaboration of Astrium GmbH, which is project manager, Bosch SatCom, GMD-Fokus and the German Aerospace Center (DLR). The preparation phase of the project will investigate the concept of the communications infrastructure and the experiments that could be realized when the MEOs are launched. This stage has been completed in February 2001. An additional study phase followed, which will be completed with a presentation in July 2002. Briefly the following aspects have been studied by DLR in the preparation phase: the overall concept of experimental communication services for Columbus, the system requirements and network topology, the relevant protocol and hardware architectures, useful satellite constellations and link scenarios. Two phases could follow the preparation phase, in phase one the satellite will be launched and the link will be tested. In phase two the satellites will be connected to the ISS. Copyright © 2002 John Wiley & Sons, Ltd. [source] Com 2.0: A path towards web communicating applicationsBELL LABS TECHNICAL JOURNAL, Issue 2 2008Paul Labrogere Providing key architecture and components that allow users to produce their own communicating Web applications as easily as producing Web content for digital assets today would open new perspectives for communication actors and would increase potential connections by an order of magnitude. The end of the walled garden model in the telecommunication world leads to an ecosystem where the user interoperates more directly with the communication service providers to define services based, for example, on presence, address book, or instant messaging. Com 2.0 is to the communication world what Web 2.0 has been to the Web: a second perceived generation of communication services. Com 2.0 uses the Web as a platform for communication and thus enables a true convergence of communication, information, and entertainment in a way that turns the user into a communication service provider. © 2008 Alcatel-Lucent. [source] Subscriber data management in IMS networksBELL LABS TECHNICAL JOURNAL, Issue 4 2006Daniel F. Lieuwen Next-generation communication services will be driven by increasingly rich and distributed subscriber information. Current wireless networks have evolved such that subscriber information now resides in various elements (e.g., home location register [HLR], prepay, voice mail, short message, and location determination systems). Convergence with the Internet promises significantly more personal information, such as presence, calendars, address books, buddy lists, pictures, and video. The home subscriber server (HSS) in the IP Multimedia Subsystem (IMS) architecture provides centralized storage for subscriber data. However, some application servers will also have their own subscriber data. As the quantity and variety of applications grow, it will become increasingly useful to provide unified views of subscriber data both within a network and across networks. The Lucent DatagridÔ software provides a telecom-targeted data integration capability, so that applications can use a logical "single-point-of-access" for user profile information inside a service provider's network. © 2006 Lucent Technologies Inc. [source] Web communication services and the PacketIN® application hosting environmentBELL LABS TECHNICAL JOURNAL, Issue 1 2002Yang Chen Large telecommunication customers are migrating their network infrastructure to support new converged services, while containing their operating costs. Deploying converged services on the networks today represents great opportunities to network service providers for new revenue generation. It brings big challenges as well, due to the requirements for a service platform with high capability to deal with the complexity of the network infrastructure, the difficulty of interoperability between different service platforms, and the diversity of signaling protocols and application programming interfaces (APIs). The Lucent PacketIN® application hosting environment (AHE) provides a solution that empowers network service providers to deliver a wide variety of enhanced services over the converged (packet and circuit, wireline and wireless) networks. It enables the creation and deployment of enhanced services on converged networks via the open service platform with interoperability, programmability, scalability, and wide protocol compliance. In particular, a new class of services is presented to demonstrate the transformation of telecommunication services that is enabled through Web presence. This article gives an overview of the PacketIN AHE with the focus on the customer values, the architecture, and enabling capability to deploy advanced applications and services. A new service portal, enterprise communication, is presented as an example of the innovation and implementation enabled by the service enabling environment. The enterprise communication provides Web access to presence information, instant messaging, third-party call management, and location. This convergence of features is enabled by the PacketIN AHE integration of the public switched telephone network (PSTN), session initiation protocol (SIP), and H.323 protocols through standard open APIs. The voice communication protocols are combined with a Web access interface to establish a new Internet presence, while leveraging existing switching products and reusing deployed communication networks and services. © 2002 Lucent Technologies Inc. [source] Optimization of Network Topologies for Service Providers in the Telecommunications MarketINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 6 2001Dieter B. Pressmar Following the deregulation of communications services, a growing number of commercial providers are offering global voice and data communications services via rented infrastructures. These service providers are faced with the challenge to determine cost-effective network-topologies, considering both the variety of contractual arrangements with national and international network providers, and the communication profiles of their customers. This paper introduces a planning model for solving the optimization problem outlined above. The model is evaluated on the basis of mixed-integer optimization. Practical deployment of this approach is discussed with respect to the run-time characteristics of the MIP solvers. Subsequently, a genetic algorithm is applied to the model and the results are compared to those of the mixed-integer optimization. [source] Implementing a management system architecture frameworkBELL LABS TECHNICAL JOURNAL, Issue 4 2000William C. Goers Any practical vision for the evolution of communications services must include a strategy for how networking vendors make it possible for service providers to manage their networks. While the Telecommunications Management Network (TMN) framework has proponents, the IP services community has shown little interest. Furthermore, operations systems developers have long attempted to produce the best framework, but the technology is outdated before it exists. This paper addresses both issues by presenting an application-driven model for integrated management. This model can be applied to either a "classic" framework orientation or a management application view. What is common between these two views are a management portal, common data models, multiple interface technologies, open and simple network element interfaces, and common operations, administration, and administration (OA&M) tools. These are the elements for which there needs to be a consistent set of interface definitions. They form the basis for the construction of next-generation management applications. [source] | ||||||||||