共查询到20条相似文献,搜索用时 15 毫秒
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Within the standard IMS framework, the value-added service is executed in the Application Server (AS) when the expected event happens. In order to be aware of the event, the AS should be inserted into the SIP signaling path at the beginning of the call to monitor the call progress. As a result, all SIP messages related to the session have to be relayed to the AS to determine whether the service is to be executed or not. However, some services are rarely executed; that is, the procedure of relaying messages to the AS seems unnecessary for most cases of these services. This paper proposes a distributed service invocation function (DSIF) to eliminate the unnecessary relay. The DSIF works as an overlay on the top of the current IMS infrastructure that enables operators to deploy it without any change in the existing IMS core; thus, it can be applied transparently to SIP dialogs between the S-CSCF and the AS. The DSIF consists of two functional entities: the Core network-SIF (C-SIF) and the Application side-SIF (A-SIF), and one database node: DB-DSIF. The C-SIF is responsible for allowing the messages to be relayed to the AS only when the service really needs to be executed. The operation of C-SIF is based on two new defined types of filter criteria: trigger Filter Criteria (tFC) and execution Filter Criteria (eFC), which are stored in the DB-DSIF. The A-SIF is in charge of interacting with the AS for service invocation. Our study indicates that the DSIF achieves a shorter service invocation time with a lower message transmission cost. We also demonstrate its feasibility by implementing a prototype on Open IMS Core platform. 相似文献
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针对IMS(IP Multimedia Subsystem)中已注册用户的重注册过程,提出了一种改进的快速重注册方法.由于已注册用户的UE(User Equipment)已经记录归属地S-CSCF(Serving-Call Session Control Function)的地址信息,因此在重注册过程中,通过在REGISTER消息中携带S-CSCF的路由信息,让REGISTER消息直接从拜访地的P-CSCF(Proxy-Call Session Control Function)转发到归属地的S-CSCF,可以有效地减少重注册延时.分析结果显示,改进的快速重注册过程要优于标准重注册过程和已有的一些改进过程.同时,它对网络的改动较小,容易实现. 相似文献
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IMS中核心网元S-CSCF的可靠性是保障IMS服务连续性的关键,是部署商用IMS网络的前提。在分析了S-CSCF功能特点的基础上,设计和实现了一种S-CSCF可靠性方案,给出了在S-CSCF提供服务的过程中,需要备份的内容、备份的时机、保证数据一致性策略、故障检测与主备服务器切换策略以及恢复策略,并在开源项目OpenIMSCore中实现和验证了该方案。实验结果表明,这一方案有效可行、备份代价较小,当工作机S-CSCF1发生故障时,备份机S-CSCF2能够在不影响服务用户的体验的情况下,迅速恢复服务。 相似文献
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This paper analyzes the session setup delay in the IP multimedia subsystem (IMS) with the CDMA2000 evolution data only rev. A (EV-DO rev. A) standard for wireless transmission. Session setup delay is particularly critical for interactive multimedia applications, such as gaming, push-to-X and voice over IP (VoIP), as it directly translates in user perception of service quality. Keeping signaling delay low, however, is a challenge in IMS due to the text-based nature of the session initiation protocol (SIP) for signaling, and, more significantly, due to the lossy and capacity constrained wireless links. To address this challenge, we analyze the session setup delay end-to-end, by taking into account key system properties across all layers, ranging from radio links to IMS signaling architecture. We present a model for cross-layer performance analysis and simulation, which includes the statistical properties of the EV-DO (rev. A) wireless channel, and also takes into consideration the properties of transport protocols (TCP, UDP) and SIP signaling (message size and compression). By means of analysis and simulations, we study the setup delay performance of a generic, multi-operator IMS communication scenario between two mobile users. We describe how session setup delay can be estimated and reduced in realistic IMS settings and we propose architecture alternatives to the basic IMS scenario. The results derived from this study show that the proposed methods can incrementally lead to a lower setup delay and less sensitivity to the radio transmission quality and frame error rate compared to the base IMS scenario 相似文献
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在分析IMS(IP Multimedia Subsystem)的注册过程后,提出一种基于缓存的改进注册过程.在UE(User Equipment)向S-CSCF(Serving-Call Session Control Function)注册的第一次交互过程中,让P-CSCF(Proxy-CSCF)缓存通过DNS组合查询得到的I-CSCF(Interrogation-CSCF)的地址信息,再让I-CSCF缓存它为用户选择的S-CSCF的地址信息.在UE与S-CSCF的第二次交互过程中,相关实体直接从缓存中提取之前保存的地址信息,以此加快用户的注册过程.分析结果显示,改进的注册过程要优于标准的注册过程.同时,它对网络的改动较小,容易部署和实现. 相似文献
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基于IP多媒体子系统(IMS)的IPTV引入集中式SIP会话管理机制,除对业务控制功能(SCF)服务器提出更高的响应性能要求,而且由于SIP的事务和对话双重完整性,对传统负载均衡技术也带来诸多限制。针对SCF的性能瓶颈,结合IMS的业务触发过程和IPTV业务的会话统计特性,探讨了集群间区分业务和集群内对后台服务器负载感知的多级负载均衡机制,并提出基于SIP事务优先级的轻量级动态权值随机调度算法。最后在IPTV原型系统中验证了该负载均衡机制的技术可行性,并给出具体实验方案。 相似文献
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IMS,IP多媒体子系统,为下一代网络用户服务提供强大的会话和服务体系结构平台。简要回顾了IMS的发展历程;详细介绍了IMS的体系结构,阐述了IMS机构的三层:应用层、会话控制层、传输与端点层的基本技术与功能;从兼容性、管理、安全三个方面分析了IMS的特点.;展望未来IMS的应用前景。 相似文献
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在分析IMS(IP Multimedia Subsystem)的注册过程后,提出一种改进的位置更新注册机制.该机制采用分层位置管理的思想,让P-CSCF(Proxy-Call Session Control Function)记录UE(User Equipment)的IP地址,S-CSCF(Service-Call Session Con-trol Function)记录为该UE服务的P-CSCF的地址,不再记录UE的IP地址,使得UE在发生位置更新时,尽可能少产生注册信令,让信令尽量限制在拜访网络.优化机制同时考虑UE与P-CSCF之间的安全问题,利用已有的安全数据让新P-CSCF对UE进行认证和建立安全联盟.分析结果显示,本文提出的改进的位置更新注册机制要优于已有的一些算法. 相似文献
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《Information Security Journal: A Global Perspective》2013,22(3):139-148
ABSTRACT A packet-based network to provide telecommunication services independent from the underlying access and transport technologies is known as a next generation network. An IP multimedia subsystem (IMS) provides an architectural framework for the next generation networks and includes variety of services such as presence, instant messaging, push-to-talk over cellular, multiparty conference, and so forth. IMS-based instant messaging is available in two flavors (immediate messaging and session-based messaging). Both flavors are subject to different types of security threats. An attacker can generate an immediate messaging flood by sending enormous number of messages to deny the services to a group of users or to an individual. Session-based messaging is facing threats such as invite flooding attack, session modification attack, and session teardown attack. In this paper, we developed a security mechanism, consisting of three layers, to secure the messaging service from flooding attacks and session-based attacks and the like. The simulation results show a good improvement in the existing security mechanism of the IMS-based instant messaging service. 相似文献
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IMS可以针对用户不同的需求提供广泛的增值多媒体业务,通过专门的SIP应用服务器可以在IMS网络之上实现这些业务。本文主要讨论当用户获得一个IMS订购关系且其订购关系包含一些增值业务时,如何创建业务专用的数据即过滤规则;当用户在IMS网络上发起业务请求时,通过业务控制机制将SIP请求正确的路由到应用服务器,以执行相应的业务逻辑。 相似文献
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Summary. A complete communication system is broken down into a number of protocol layers each of which provides services to the layer
above it and uses services provided by its underlying layer. A service specification defines a particular ordering of the
operations that a given layer provides to the layer above it. The active elements in each layer are called entities and they
use a protocol in order to implement their service definition. On the basis of this relation between the service and protocol
concepts we have developed algorithms for deriving protocol entity specifications from a formal service specification. The
derived protocol entities ensure the correct ordering of the service primitives by exchanging synchronization messages through
an underlying communication medium. This paper presents an extended version of our earlier derivation algorithms. This version
of the algorithm can handle all operators and unrestricted process invocation and recursion as defined by basis LOTOS. The
correctness of this derivation algorithm is formally proved.
Received: January 1992 / Accepted: February 1996 相似文献
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Niklas Blum Piotr Jacak Florian Schreiner Dragos Vingarzan Peter Weik 《Journal of Network and Systems Management》2008,16(1):63-91
The IP Multimedia Subsystem (IMS), already widely recognized as a fundamental core component of Next Generation Networks (NGNs),
enables proliferation of a huge variety of value added services. Simultaneous to the emergence of triple play services there
is a strong need for establishing standardized methodologies for service fulfillment and assurance, maintaining service execution
parameters at advertised levels. Traditional Operations Support Systems (OSS) are not adequate for managing NGNs. This work
shows experiences gained from implementing OSS for NGNs. It describes a solution that combines extensive NGN development expertise
with a new generation, of policy-based, service oriented OSS solutions in order to provide enhanced levels of automation and
reliability to the NGN service delivery and session control environment. Primary focus of this approach is put on service
assurance and service fulfillment mechanisms for remote monitoring, automated control and configuration of standard compliant
IMS infrastructures, such as the Open Source IMS Core (OSIMS) based Open IMS Playground. This work describes state of the
art NGN OSS design principles and knowledge attained by integration of standardized fault management as well as service and
subscriber provisioning procedures showing how the full cycle from service deployment to service advertisement to service
execution can be delivered in an automated way.
相似文献
Peter WeikEmail: |
16.
《Computer Networks》2007,51(8):2015-2032
Proportional delay differentiation (PDD) is an important service model for providing relative differentiated services on the Internet. It aims to maintain pre-specified packet queueing-delay ratios between different classes of traffic at each hop. Existing rate-allocation approaches for PDD services assume the average queueing delay of a class is inversely proportional to its service rate. This assumption is not necessarily valid when the system is not heavily loaded. To provide consistent PDD services under various load conditions, in this paper, we propose a novel rate-allocation approach that applies fuzzy control theory to capture the nonlinear relationship between the queueing delay and the service rate. In the approach, a class’s service rate is adjusted according to a set of fuzzy control rules defined over its error (the difference between the target delay ratio and the achieved one), the change of error, and the change of service rate. We prove that the fuzzy control system is stable and the service rate of a class converges to its equilibrium point at steady state. Simulation results demonstrate that, in comparison with other rate-allocation approaches, the fuzzy control approach is able to provide consistent PDD services under wide range load conditions. It is also shown robust under various system conditions, including with multiple classes, changing target delay ratios, changing load conditions, and different traffic patterns. 相似文献
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通过对IMS业务体系、业务触发机制进行分析,提出了基于ICSI进行业务控制以及基于缺省i FC进行业务触发控制的方法 ,从而可以阻止IMS用户使用未签约授权的业务。 相似文献