Location-Based Services in Mobile Communication Infrastructures

Location- and context-based services form a new class of services, which supplement existing services in the mobile communication infrastructure. The paper describes shortly an architecture of systems supporting the new class of services; this architecture extends beyond those systems which have initially been introduced by support of centralized data bases (such as web servers) and by federation components providing search and mapping functions which are necessary for the full exploitation of the capabilities of such services. The concept is based on the existence of heterogeneous mobile and radio access networks. The question arises, among others, to what extent such services add to the network load and its performance, in particular the question of scalability. In this paper, an approach is outlined as a basis for future capacity planning and for the support of strategic decision making with respect to infrastructure investments.     

Optimal joint utility based load balancing algorithm for heterogeneous wireless networks

The rapid development of mobile broadband services with continuously increasing traffic volumes has resulted in a number of challenges, including ubiquitous network coverage, high bandwidth, and reliable services for reasonable price, etc. To address these challenges, evolved packet system (EPS) is proposed as the evolution of the packet core network. While resource management and load balancing issues in EPS are discussed in 3GPP standardization, relatively few research works consider mechanism design for load information monitoring and evaluation. Furthermore, even though some load balancing algorithms have been proposed for integrated networks, the load balancing scheme design which achieves the optimization of joint system performance has not been extensively studied. In this paper, an inter-access system anchor based load balancing mechanism is introduced which performs load monitoring and evaluation for access gateways and networks, and an optimal load balancing algorithm is proposed for heterogeneous integrated networks. To characterize the performance of integrated networks, the concept of utility function is introduced and the comprehensive performance of integrated networks which support both single type service and multimedia service is modeled mathematically. Applying vertical handoff as an efficient mechanism for achieving load balancing, the optimal number of handoff users is obtained through solving the optimization problem. Numerical results demonstrate that load balancing between access networks can be achieved, and the optimal number of handoff users corresponding to the maximal joint network utility can be obtained.     

The estimation of signaling delay in ATM networks

In multimedia applications over ATM networks, more stringent quality of services are required, because these applications are especially sensitive to the time delay. In this letter, a simple estimation of signaling delay is presented using Erlang service models according to ITU-T “Q.2931”. Additionally, the call blocking probability of a realistic network is considered. The simulation results show that the proposed model can be an effective tool to estimate the setup delay. If the connection setup delay can be effectively estimated according to the network load, then the users may decide whether or not to join this congested network, and thus contributes to the load balance of ATM networks     

考虑负载均衡的系统保护通信专网路由规划方法

针对系统保护通信专网局部节点与链路业务负载过重的问题,提出一种考虑负载均衡的系统保护通信专网路由规划方法.首先,阐述了系统保护通信专网的概念,分析了局部节点和链路业务负载过重的问题;然后,构建了综合考虑业务特性和备份路径的负载均衡路由规划优化模型,实现了模型的负载均衡路由规划求解;最后,以某省系统保护通信专网光传送网(...     

A simulation based approach for network resources dimensioning in video delivery systems

The availability of high-performance networking technologies and processing power allows creation of new multimedia services and applications in broadband integrated services networks. Such new services will be successful only if delivered to end-users at low cost. At present, for wide-area distributed systems, communication has a relevant impact on the overall costs. As a consequence, adequate methodologies for an efficient dimensioning of the network resources need to be devised. Simulation techniques represent a powerful instrument for the analysis and evaluation of real systems. This paper, moving from the definition of mathematical models for VBR video sources, presents the application of a simulation approach to verify the compatibility of the communication load related to a set of video streams with the data transport capability of an existing network architecture for the delivery of video streams, in the case of CBR communication links.     

Performance of Hierarchical Aggregation in Differentiated Services Networks

We address the use of hierarchical aggregation in DiffServ networks. We propose two analytical models to study the tradeoffs between signaling load and resource utilization. In the case of the signaling load, we introduce a novel performance metric that captures, simultaneously, the state information stored and the rate of signaling messages processed at routers. In the first analytical model, based on multidimensional birth–death processes, the offered load is detailed at the flow level, which allows accurate assessment of the signaling load. The second analytical model accommodates time-varying offered loads, which allows studying the tradeoffs between the time-scale of the aggregate demand and the time-scale of signaling. Our results, which also include analysis using measured traces, show that hierarchical aggregation can introduce very high signaling gains with a small penalty in terms of resource utilization, allowing significant savings in terms of network cost.     

Effects on TCP of routing strategies in satellite constellations

A broadband satellite network uses a constellation of a number of similar satellites to provide wireless networking services to the Earth. A number of these constellation networks are under development. This article introduces the types of satellite constellation networks, and examines how overall performance of TCP communications carried across such a network can be affected by the choice of routing strategies used within the network. Constellations utilizing direct intersatellite links are capable of using multiple paths between satellites simultaneously as a strategy to spread network load. This allows more general routing strategies than shortest-path routing, but we show these strategies to be detrimental to the performance of individual TCP connections     

A new architectural approach for optical burst switching networks based on a common control channel

The new architectural approach to Optical Burst Switching networks presented here features a common control channel and a node locally maintained network model. The Common Control Channel allows for a fast and efficient broadcast of the network Control Packets, which in turn are used by every node to update its Local Network Model. The Local Network Model allows efficient network resource planning as each node is aware of the reservation status intentions for the resources on each node. This paper describes the new C³-OBS architecture, evaluates its comparative performance to regular OBS, assesses the manageable bandwidth for a C³-OBS network and evaluates the common control channel manageable load. The concept of “Well-Informed Node” is defined as a metric of trustfulness on the information managed by the Local Network Model and the scope and application of C³-OBS networks are studied.     

PHS roaming signaling protocol architecture toward global mobilitynetwork

The network for supporting the global personal communication is called the global mobility network (GLOMONET), where global mobility is guaranteed by coordination between intelligent networks (INs). This paper describes the implementation of a roaming signaling protocol for the personal handy-phone system (PHS) GLOMONET, clarifying the concepts of the PHS architecture regarding the GLOMONET. The PHS is a more economical personal communication system than existing cellular systems, by introducing the concept that the PHS service is provided by the most effective use of the existing ISDN and IN functions, where the majority of network functions to provide ISDN services are commonly used for functions for PHS service provision. The PHS mobility function realized by the IN guarantees flexible and effective roaming service provision for the globalization of future personal communication. The proposed PHS signaling protocol architecture is based on the intelligent network capability set 2 (IN CS2) defined by the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Study Group 11 and a visitor location register (VLR) database scheme with efficient signal transfer in the GLOMONET. The PHS specific roaming signaling protocol is defined by the service-independent IN application protocol (INAP). The proposed PHS concepts and roaming signaling protocol were reflected to the national telecommunications standards in the Telecommunication Technical Committee (TTC) and standards in the PHS-memorandum of understanding (MoU)     

Self-configuring communication middleware model for clusters with multiple interconnections

Communication middleware such as MuniCluster provides high-level communication mechanisms for networked applications by hiding the low-level communication details from the applications. The MuniCluster model provides mechanisms to enhance the network performance properties through message separation and parallel transfer. However, the configurations of such services require various measurements and setups to efficiently utilize the availability of multiple network interfaces. In this paper we introduce and evaluate a self-configuring model that allows applications to transparently utilize the existence of multiple network interfaces and networks. Here we present enhancements to the MuniCluster model by adding the self-configuration mechanism. Using network resource discovery and deciding on how to efficiently utilize the multiple networks, the model enhances overall communications performance. The proposed techniques deal with the heterogeneity of interfaces and networks to enhance the communication performance transparent form the applications. The proposed techniques also deal with heterogeneity in the interfaces and networks in their numbers, latencies, and bandwidths.     

Situation-aware wireless networks

The task of implementing a dynamic planning tool for wireless networks is a complex and multilayered problem. The following article explains the concept of dynamic planning and highlights the challenges involved. A system architecture that allows networks to be self-organizing is presented, and the concept of situation awareness is introduced. The resulting functionality endows network elements with the intelligence to react dynamically to perturbations. Location-aided planning is currently receiving much attention from the research community; its application to situation awareness is discussed. The use of game theory to solve resource contention in competitive scenarios is highly effective. Adaptors that are specific program modules are used to launch countermeasures and are demonstrated in this article through an example. A number of key results associated with the concept of reconfigurability are presented. Finally, a new planning paradigm based on local interaction is introduced and relevant conclusions are drawn.     

网络性能仿真软件综述

网络性能仿真有助于网络运行数据的统计和网络性能的分析,对网络的设计、运营、优化与综合评估至关重要.由于网络的异构性、数据传输过程的复杂性、业务属性的多变性和网络设备的局限性,传统网络性能仿真方法难以确保所获取仿真结果的准确性.网络性能仿真软件通过搭建网络模型和模拟真实网络场景下的信息传送过程,可获取高可信度的仿真结果,...     

Distributed rate adaptive packet access (DRAPA) for multicell wireless networks

Fueled by the explosive growth of the Internet, applications are demanding higher data rates and better services. Given the scarcity of radio resources, higher network capacities need to be achieved through more efficient use of the available bandwidth. Current cellular networks utilize frequency planning schemes that are optimized for circuit-switched applications, and thus is inherently problematic for future wireless packet networks with bursty, high peak-rate traffics. Random access schemes such as the ALOHA are seen as better solutions for packet networks. However, co-channel interference may significantly reduce the network throughput when the multicell load is heavy. In this paper, we propose a distributed rate adaptive packet access (DRAPA) scheme to combine the advantages of rate adaptation (in circuit-switched networks) and random access (in packet-switched networks). In particular, DRAPA allows terminal stations to transmit packets in random access fashion in the presence of brusty interference from neighboring cells. The packet code rate is adjusted according to interference level so that the retransmisson is controlled at an acceptable level. The DRAPA scheme subsumes two traditional schemes as the extreme cases, and has superior performance over the traditional schemes in terms of throughput and stability.     

Performance management of multiple access communication networks

This paper focuses on conceptual design, development, and implementation of a performance management tool for computer communication networks to serve large-scale integrated systems. The objective is to improve the network performance in handling various types of messages by on-line adjustment of protocol parameters. The techniques of perturbation analysis of Discrete Event Dynamic Systems (DEDS), stochastic approximation (SA), and learning automata have been used in formulating the algorithm of performance management. The efficacy of the performance management tool has been demonstrated on a network testbed. The conceptual design presented offers a step forward to bridging the gap between management standards and users' demands for efficient network operations since most standards such as ISO (International Standards Organization) and IEEE address only the architecture, services, and interfaces for network management. The proposed concept for performance management can also be used as a general framework to assist design, operation, and management of various DEDS such as computer integrated manufacturing and battlefield C³ (Command, Control, and Communications)     

A concept of communication distance and its application to six situations in mobile environments

Wireless networks combined with location technology create new problems and call for new decision aids. As a precursor to the development of these decision aids, a concept of communication distance is developed and applied to six situations. This concept allows travel time and bandwidth to be combined in a single measure so that many problems can be mapped onto a weighted graph and solved through shortest path algorithms. The paper looks at the problem of intercepting an out-of-communication team member and describes ways of using planning to reduce communication distance in anticipation of a break in connection. The concept is also applied to ad hoc radio networks. A way of performing route planning using a bandwidth map is developed and analyzed. The general implications of the work to transportation planning are discussed.     

Performability analysis of common-channel signaling networks, basedon signaling system 7

Within integrated services digital networks (ISDN), all inter-change signaling messages for ISDN and intelligent network (IN) call controls are carried through a common channel signaling network (CCSN) as a backbone signaling network. Since CCSN usually have very strict reliability requirements as well as good performance objectives, performance and reliability of CCSN need to be jointly analyzed. This paper evaluates the mean end-to-end delay of a single-mated pair (SMP) CCSN for various call-arrival rates in a normal state and several failure states, as a performance index. As a performability index, this paper also analyzes the mean time to unreliable operation (MTUO) of a given network for various call-arrival rates at each signaling end point (SEP) and the failure rate of each signaling transfer point (STP). These results can be used in the design of common-channel signaling networks. This performability evaluation can be further studied for varying the failure rates of SEP and linksets, and the various threshold values of the unreliable operation     

Service management in multiparty active networks

Active networking is an expanding field of research. It includes the ability to easily install and modify customized network services and to process packets within the network in a customized way. This article addresses the question of how the benefits of active networking can be exploited in an environment where a large number of customers must share a common network infrastructure. We introduce a management framework for active networks that allows customers to deploy and manage their own active services in a provider domain. The key concept in our framework is the virtual active network. From the customer perspective, the VAN represents an environment in which the customer can install, run, and manage active services without interaction with the VAN provider. From the VAN provider perspective, the VAN represents the object of resource partitioning and customer isolation. Active networking combined with the VAN concept allows for new business models in the telecom industry