Common channel signalling system number 7 for ISDN and intelligentnetworks

Various functional parts of signalling system number 7 and the underlying concepts are described. The unique attributes of the lower and higher functional layers are discussed. Applications of signaling system number 7 for call control and for transaction services are presented. The signaling transfer point makes signalling networks possible. Using the lower layers of the protocol, it provides routing capability for signaling messages between the exchange offices and access of these exchange offices to the network databases. The author discusses the performance parameters associated with the signalling transfer point and examines its implementations     

Building a signaling protocol architecture for future mobile networks

Third-generation mobile systems are emerging. These systems will support a unified user access to a variety of services, including the existing mobile and fixed network (PSTN, N-ISDN) services, the enhanced multimedia and multiparty services envisaged for broadband networks, and personal communication services as well. The role of signaling is predominant in building a flexible, efficient, and evolving system. The aim of this paper is to provide a framework for developing a signaling protocol architecture for future mobile networks. The study especially focuses on the universal mobile telecommunication system (UMTS). Within this framework various design and operational requirements imposed on UMTS can be satisfied. A method to deal with the functional complexity of UMTS is provided. Mobile networks are viewed as integral parts of the broadband infrastructure and are built upon the IN principles.     

Evolving intelligent interexchange network-an SS7 perspective

The role of common channel signaling, referred to as Signaling System No.7 (SS7), in the evolution of services in an interexchange carrier environment is discussed. The importance of SS7 in evolving the intelligent network necessary to support these services is addressed. Interworking with virtual private networks via the out-of-band ISDN messaging channel (D-channel) to extend the capabilities of SS7 network signaling to customer networks is also discussed. For ubiquitous support of ISDN, CLASS, and future services, the interworking of interexchange SS7 with domestic local exchange carriers as well as foreign administrations is critical. This service and intelligent network evolution is described. Emphasis is placed on services and the anticipated migration to those types of services which demand an intelligent interaction and close coupling of both virtual private networks and local public switched networks to the interexchange network     

Application-Level QoS Negotiation and Signaling for Advanced Multimedia Services in the IMS

The IP multimedia subsystem (IMS) has been recognized as a reference next-generation network architecture for offering multimedia services over an Internet Protocol (IP)-based infrastructure. One of the key benefits of the IMS is efficient and flexible introduction of new services and access to third-party application providers, thanks to standard interfaces and standardized service capabilities. To support novel media-rich applications across a wide range of user devices and access networks, IMS must support negotiable quality of service (QoS) for IP multimedia sessions. In this article, we describe the application-level QoS signaling as specified by the 3GPP and propose some enhancements based on advanced QoS parameter matching and optimization functionality to be included along the signaling path. We outline various signaling flow scenarios and discuss them in the context of a case study involving an IMS-supported 3D virtual environment, featuring a treasure-hunt-like game.     

Wireless ATM networks: technology status and future directions

The concept of “wireless ATM” (WATM), first proposed in 1992, is now being actively considered as a potential framework for new-generation wireless communication networks capable of supporting integrated, quality-of service (QoS) based multimedia services. In this review paper, we outline the technological rationale for wireless ATM, present a system-level architecture, and discuss key design issues for both mobile ATM switching infrastructure and radio access subsystems. The WATM radio access layer issues covered in this paper include: spectrum allocation; spectrum etiquette; modem technology; and medium access/data link control (MAC/DLC) protocols. Mobile ATM aspects such as ATM signaling extensions for handoff control, location management, and mobile QoS control are discussed. A summary of current wireless/mobile ATM technology development and standardization status is given, including an outline of our WATMnet prototype. The paper concludes with a discussion of future directions for wireless ATM technology such as Internet protocol (IP) integration and mobile multimedia terminals/applications     

Signaling System No. 7 ISDN User Part

The integrated services digital network (ISDN) user part of Signaling System No. 7 defines the signaling protocol which supports the establishment, supervision, and release of voice and nonvoice calls over circuit-switched connections between ISDN terminations of digital subscriber access lines. This paper gives an overview of the ISDN user part protocol, as defined in CCITT Recommendations Q.761-Q.766 [1], in terms of the signaling functions and procedures provided to support call and connection control in an ISDN, and in terms of the information elements and signaling messages that are used by the signaling functions in ISDN exchanges to communicate.     

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access     

A service-based RBAC & MAC approach incorporated into the FHIR standard

Health Information Exchange (HIE) provides a more complete health record with the aim to improve patient care with relevant data gathered from multiple Health Information Technology (HIT) systems. In support of HIE, the Health Level Seven (HL7) XML standard was developed to manage, exchange, integrate, and retrieve electronic health information. In 2011, the Fast Healthcare Interoperable Resources (FHIR) standard, based on HL7, was proposed to facilitate the development of mobile Health (mHealth) apps with HIT data sharing via a common modeling format. FHIR utilizes RESTful APIs enabled with a FHIR server for information usage and exchange in the cloud. FHIR has a security specification, but does not define actual security mechanisms for secure data exchange via service invocations. If services are the primary means of access, there must be a way to control who can invoke which service at which time. This paper proposes the use of Role-Based Access Control (RBAC) and Mandatory Access Control (MAC) to define permissions based on role and/or the sensitivity level of services. This is accomplished by evolving RBAC and MAC to support permissions on services (as opposed to the usual object view) at a model level applied to a setting where a mobile application is using RESTful APIs. The resulting service-based model is incorporated into the FHIR standard to control the access of who can invoke which services of FHIR RESTful APIs that manage the sensitive healthcare data; work is demonstrated via an mHealth application that interacts with the OpenEMR HIT system via the HAPI FHIR server.     

True number portability and advanced call screening in a SIP-basedIP telephony system

Custom local area signaling service features offered in the PSTN have certain limitations due to the closed nature of PSTN network signaling. The adoption of telephony over IP (IP telephony) will enable a new paradigm of services and features that are not possible to implement in today's PSTN. This is especially the case for services that make use of personal, trusted information, which can be provided by a user's personal digital assistant. We demonstrate how personal information can be coupled with an IP telephony service to provide user-customized call handling by the network. In particular, we describe a demonstration architecture that includes Ethernet-attached phones running SIP, with an interface to synchronize with PDAs that supply personal information. The proposed architecture is quite flexible; it can support enhanced versions of the current PSTN and private branch exchange services, in addition to many new features and services. We describe true number portability and advanced call screening as examples of new services in a hybrid PSTN/IP telephony environment     

Providing QOS support at the distributed wireless MAC layer: a comprehensive study[medium access control protocols for wireless LANs]

Holding the promise of making ubiquitous mobile access to IP-based applications and services a reality, wireless local area networks have been deployed in an unlimited way over the last few years. Due to their robust characteristics, distributed MAC protocols are the most widely used mechanisms to arbitrate access to the wireless channel. However, their ability to achieve high medium usage efficiency while providing services with meaningful performance assurances is being challenged by a wide range of existing and emerging applications that have lately migrated from other telecommunication networks to wireless environments. This article aims to provide a comprehensive study of the limitations and merits of mechanisms that have been proposed toward embedding QoS support to distributed wireless MAC protocols. A hybrid scheme that incorporates signaling and information sharing is proposed, and extensive simulation experiments are run to assess the efficiency of the access schemes in maximizing utilization of the wireless bandwidth while providing QoS support for heterogeneous applications.     

Implementing ISDN in the United States

Planning for implementation of ISDN is proceeding at a rapid rate throughout the United States. Planning for nationwide deployment of common-channel signaling to support database access, as well as internode signaling for ISDN is also underway. This paper describes planning for trials and initial applications of ISDN and common-channel signaling for service starting in late 1986 through early 1988, as well as ISDN demonstrations, some already in operation. In addition, this paper discusses the network and regulatory environment for ISDN implementation in the United States, standards for the U.S. environment, and trials of transition services.     

PCS mobility support over fixed ATM networks

As broadband multimedia services and wireless services become popular, there is growing interest in the industry to support ATM over a wireless link, and wireless access to fixed ATM networks. We focus on the internetworking of PCS and ATM networks, in which the air interface remains one of the PCS standards and the backbone is an ATM network with mobility support. It is desirable to minimize the impact of the internetworking and mobility support on the existing/emerging PCS and ATM specifications. A network architecture, a protocol reference model, and signaling protocols for PCS mobility support over fixed ATM networks are described. They are compared against other implementation alternatives and the trade-offs are discussed. Some performance results of the proposed architecture are also presented     

Developing applications for Internet telephony: a case study on the use of parlay call control APIs in SIP networks

Applications offered to end users as value-added services, or more simple, services, are crucial for the survival and success of service providers. Two main sets of standards have emerged for Internet telephony: H.323 from the ITU-T and SIP from the IETF. Unfortunately, the related application development frameworks are rather weak. Parlay, a set of standard object-oriented and signaling protocol-neural APIs, is an alternative. It allows applications to access network functionality, including call control, in a controller manner. Call control makes it possible to establish, modify, and tear down calls. It is the main functionality offered by Internet telephony networks. We have built a call control application in a SIP environment, using the call control APIs offered by Parlay. The application is a multiparty game. This article describes the case study. The mapping of the APIs onto SIP is presented, and its implementation is described. Related work reviewed, and the lessons learned are discussed. Parlay call control APIs are suitable for application development in Internet telephony. However, well isolated extensions are needed to realize their full potential.     

A radio system proposal for widespread low-power tetherlesscommunications

It is suggested that low-power digital radio as an access technology could be integrated into a local exchange network to provide a ubiquitous personal communications network (PCN). High-quality tetherless communications services that could be provided by such an exchange-network-based PCN are described. A possible low-power exchange access digital radio system for providing these exchange-network based PCS services is discussed. The radio system uses a spectrum-efficient time-division multiple-access (TDMA) architecture made possible by advanced digital signal processing techniques. Control of the frequency reuse system is described, and frequency spectrum needs are indicated     

Quality-of-service signaling for next-generation IP-based mobile networks

We present a novel end-to-end QoS architecture that enables seamless services over heterogeneous wireless access networks. We discuss the main architectural approaches and design issues of mobility-aware QoS signaling in IP networks. Then we introduce a QoS signaling architecture that integrates resource management with mobility management. It is based on a domain resource manager concept and nicely supports various handover types in an integrated approach. In particular, we support anticipated handover with pre-reservation of resources over the old network before the mobile node is attached to the new access point.     

A signaling and control architecture for mobility support in wireless ATM networks

This paper presents a signaling and control architecture for mobility support in a wireless ATM network that provides integrated broadband services to mobile terminals. A system level protocol architecture for a wireless ATM network is outlined. The proposed protocol stack incorporates new wireless link MAC, DLC and wireless control sublayers, together with appropriate mobility extensions to the existing ATM network control layer. Wireless control and ATM signaling capabilities required for mobility support are discussed, and preliminary solutions are given for selected major functions. Potential extensions to standard Q.2931 ATM signaling are proposed to support handoff and service parameter/QoS renegotiation required for mobility. An associated wireless control protocol for supporting terminal migration, resource allocation, and handoff is discussed. Preliminary experimental results are given which validate the proposed handoff control protocol on an ATM network testbed.     

A direct signaling system for flexible access and deployment oftelecommunication services

In current telecommunication networks, the value-added services available to subscribers are almost exclusively offered by the carrier providing local telephony service. This results from two factors: the processing for services is either based in or triggered from software executing on the access telecommunication switches, and signaling links over which subscribers request services are terminated on these access switches. In a direct signaling system, the signaling link from a subscriber does not necessarily terminate on an access switch, but rather on an intelligent server we call a call server. The call server invokes service functions and coordinates their interactions. This direct signaling system may be overlaid on various types of access networks, including circuit-switched telephony, packet telephony, wireless local loop, cable, etc. We discuss the design, implementation, and performance of a direct signaling system, including procedures that provide varying amounts of integration with current telecommunication systems. Our results show that a direct signaling system using a low-delay direct signaling link and in which no changes are made to existing telecommunicatione switches incurs approximately 100 ms higher postdial delay than a standard ISDN system. A direct signaling system in which telecommunication switches provide open interfaces and coordinate processing with direct signaling servers incurs approximately 100 ms lower postdial delay than a standard ISDN system     

Providing quality of service in always best connected networks

The next generation of mobile systems is expected to support multiple radio access technologies, as well as diverse types of terminals, including mobile phones, personal digital assistants, and laptops, as well as personal area, moving, and sensor networks. Thus, future wireless systems will not only continue to break technological barriers in terms of new air interface capabilities, higher bit rates, mobility, security, and QoS management, but will present new end-to-end scenarios in which applications access services over multiple L2 hops and multiple IP networks. The term always best connected refers to the concept of defining a set of access selection criteria and mechanisms that allow users to get connected to various services in a nearly optimal manner. Providing QoS in this type of heterogeneous multihop environment is a challenging task because applications may be completely unaware of them scenario and the underlying layer 2 technologies that can be quite different at different hops. For instance, some wireless links may have scarce resources and highly optimized QoS mechanisms; others may not support explicit QoS handling at all. In this article we consider the use of IP-level QoS signaling as a key component to support the end-to-end QoS for various applications. We propose a small set of application programmer- and wirelesslink-friendly IP QoS parameters (wireless hints) and illustrate the use of these in a specific WLAN-to-cellular handover situation. We conclude that the proposed model, signaling protocol, and wireless information elements can efficiently support QoS in heterogeneous mobile environments.     

Switching in a competitive market

The author examines the significance of the competitive positioning of the local exchange carriers with regard to their expectations of their network equipment providers and, in particular, the providers of the whole range of capabilities that fall within the broad category of switching. The point of view is that of a local exchange carrier whose principal products are public exchange access services, as defined by the AT&T divestiture agreement. Development of services, customer participation, transport capabilities, implementation agreements, and industry cooperation are discussed     

Design,Implementation and Evaluation of Programmable Handoff in Mobile Networks

We describe the design, implementation and evaluation of a programmable architecture for profiling, composing and deploying handoff services. We argue that future wireless access networks should be built on a foundation of open programmable networking allowing for the dynamic deployment of new mobile and wireless services. Customizing handoff control and mobility management in this manner calls for advances in software and networking technologies in order to respond to specific radio, mobility and service quality requirements of future wireless Internet service providers. Two new handoff services are deployed using programmable mobile networking techniques. First, we describe a multi-handoff access network service, which is capable of simultaneously supporting multiple styles of handoff control over the same physical wireless infrastructure. Second, we discuss a reflective handoff service, which allows programmable mobile devices to freely roam between heterogeneous wireless access networks that support different signaling systems. Evaluation results indicate that programmable handoff architectures are capable of scaling to support a large number of mobile devices while achieving similar performance to that of native signaling systems.