Service layer

Last updated

In intelligent networks (IN) and cellular networks, service layer is a conceptual layer within a network service provider architecture. It aims at providing middleware that serves third-party value-added services and applications at a higher application layer. The service layer provides capability servers owned by a telecommunication network service provider, accessed through open and secure Application Programming Interfaces (APIs) by application layer servers owned by third-party content providers. The service layer also provides an interface to core networks at a lower resource layer. [1] The lower layers may also be named control layer and transport layer (the transport layer is also referred to as the access layer in some architectures).[ citation needed ]

Contents

The concept of service layer is used in contexts such as Intelligent networks (IN), WAP, 3G and IP Multimedia Subsystem (IMS). It is defined in the 3GPP Open Services Architecture (OSA) model, which reused the idea of the Parlay API for third-party servers.

In software design, for example Service-oriented architecture, the concept of service layer has a different meaning.

Service layer in IMS

The service layer of an IMS architecture provides multimedia services to the overall IMS network. This layer contains network elements which connect to the Serving-CSCF (Call Session Control Function) using the IP multimedia Subsystem Service Control Interface (ISC). [2] The ISC interface uses the SIP signalling protocol.

Elements of the IMS service layer

The network elements contained within the service layer are generically referred to as 'service platforms' however the 3GPP specification (3GPP TS 23.228 V8.7.0) defines several types of service platforms:

SIP Application Server

The SIP Application Server (AS) performs the same function as a Telephony Application Server in a pre-IMS network, however it is specifically tailored to support the SIP signalling protocol for use in an IMS network.

OSA Service Capability Server

An OSA Service Capability Server acts as a secure gateway between the IMS network and an application which runs upon the Open Services Architecture (this is typically a SIP to Parlay gateway)

IM-SSF

The IM-SSF (IP Multimedia Service Switching Function) acts as a gateway between the IMS network and application servers using other telecommunication signalling standards such as INAP and CAMEL.

Service layer in SOA

In service-oriented architecture (SOA), the service layer is the third layer in a five-abstraction-layer model. The model consists of Object layer, Component layer, Service layer, Process layer and Enterprise layer. [3] The service layer can be considered as a bridge between the higher and lower layers, and is characterized by a number of services that are carrying out individual business functions.

See also

Related Research Articles

The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating real-time sessions that include voice, video and messaging applications. SIP is used for signaling and controlling multimedia communication sessions in applications of Internet telephony for voice and video calls, in private IP telephone systems, in instant messaging over Internet Protocol (IP) networks as well as mobile phone calling over LTE (VoLTE).

The Intelligent Network (IN) is the standard network architecture specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as mobile telecom networks. It allows operators to differentiate themselves by providing value-added services in addition to the standard telecom services such as PSTN, ISDN on fixed networks, and GSM services on mobile phones or other mobile devices.

The Parlay Group was a technical industry consortium that specified APIs for the telephone network. These APIs enable the creation of services by organizations both inside and outside of the traditional carrier environment. In fact, it is hoped that services can be created by IT developers, rather than telephony experts.

The Open Service Access or OSA is part of the third generation mobile telecommunications network or UMTS. OSA describes how services are designed in a UMTS network.

Customized Applications for Mobile networks Enhanced Logic (CAMEL) is a set of standards designed to work on either a GSM core network or the Universal Mobile Telecommunications System (UMTS) network. The framework provides tools for operators to define additional features for standard GSM services/UMTS services. The CAMEL architecture is based on the Intelligent Network (IN) standards, and uses the CAP protocol. The protocols are codified in a series of ETSI Technical Specifications.

The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS) is a standardised architectural framework for delivering IP multimedia services. Historically, mobile phones have provided voice call services over a circuit-switched-style network, rather than strictly over an IP packet-switched network. Alternative methods of delivering voice (VoIP) or other multimedia services have become available on smartphones, but they have not become standardized across the industry. IMS is an architectural framework that provides such standardization.

The Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN) is a standardization body of ETSI, specializing in fixed networks and Internet convergence. It was formed in 2003 from the amalgamation of the ETSI bodies Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) and Services and Protocols for Advanced Networks (SPAN).

A session border controller (SBC) is a network element deployed to protect SIP based voice over Internet Protocol (VoIP) networks.

The next-generation network (NGN) is a body of key architectural changes in telecommunication core and access networks. The general idea behind the NGN is that one network transports all information and services by encapsulating these into IP packets, similar to those used on the Internet. NGNs are commonly built around the Internet Protocol, and therefore the term all IP is also sometimes used to describe the transformation of formerly telephone-centric networks toward NGN.

A VoIP phone or IP phone uses voice over IP technologies for placing and transmitting telephone calls over an IP network, such as the Internet. This is in contrast to a standard phone which uses the traditional public switched telephone network (PSTN).

A service delivery platform (SDP) is a set of components that provides a service(s) delivery architecture for a type of service delivered to consumer, whether it be a customer or other system. Although it is commonly used in the context of telecommunications, it can apply to any system that provides a service. Although the TM Forum (TMF) is working on defining specifications in this area, there is no standard definition of SDP in industry and different players define its components, breadth, and depth in slightly different ways.

Vertical handover or vertical handoff refers to a network node changing the type of connectivity it uses to access a supporting infrastructure, usually to support node mobility. For example, a suitably equipped laptop might be able to use both a high speed wireless LAN and a cellular technology for Internet access. Wireless LAN connections generally provide higher speeds, while cellular technologies generally provide more ubiquitous coverage. Thus the laptop user might want to use a wireless LAN connection whenever one is available, and to 'fall over' to a cellular connection when the wireless LAN is unavailable. Vertical handovers refer to the automatic fallover from one technology to another in order to maintain communication. This is different from a 'horizontal handover' between different wireless access points that use the same technology in that a vertical handover involves changing the data link layer technology used to access the network.

Text over IP is a means of providing a real-time text (RTT) service that operates over IP-based networks. It complements Voice over IP (VoIP) and Video over IP.

System Architecture Evolution (SAE) is the core network architecture of mobile communications protocol group 3GPP's LTE wireless communication standard.

Video Share

Video Share is an IP Multimedia System (IMS) enabled service for mobile networks that allows users engaged in a circuit switch voice call to add a unidirectional video streaming session over the packet network during the voice call. Any of the parties on the voice call can initiate a video streaming session. There can be multiple video streaming sessions during a voice call, and each of these streaming sessions can be initiated by any of the parties on the voice call. The video source can either be the camera on the phone or a pre-recorded video clip.

Image Share

Image Share is a service for sharing images between users during a mobile phone call. It has been specified for use in a 3GPP-compliant cellular network by the GSM Association in the PRD IR.79 Image Share Interoperability Specification.

The 3GPP/NGN IP Multimedia Subsystem (IMS) multimedia telephony service (MMTel) is a global standard based on the IMS, offering converged, fixed and mobile real-time multimedia communication using the media capabilities such as voice, real-time video, text, file transfer and sharing of pictures, audio and video clips. With MMTel, users have the capability to add and drop media during a session. You can start with chat, add voice, add another caller, add video, share media and transfer files, and drop any of these without losing or having to end the session. MMTel is one of the registered ICSI feature tags.

IMS is a set of specifications to offer multimedia services through IP protocol. This makes it possible to incorporate all kinds of services, such as voice, multimedia and data, on an accessible platform through any Internet connection.

The Session Initiation Protocol (SIP) is the signaling protocol selected by the 3rd Generation Partnership Project (3GPP) to create and control multimedia sessions with two or more participants in the IP Multimedia Subsystem (IMS), and therefore is a key element in the IMS framework.

ViLTE, an acronym for "Video over LTE", is a conversational video service based on the IP Multimedia Subsystem (IMS) core network like VoLTE. It has specific profiles for the control and VoLTE of the video service and uses LTE as the radio access medium. The service as a whole is governed by the GSM Association in PRD IR.94.

References

  1. ↑ Kristofer Kimbler, Service Interaction in Next Generation Networks: Challenges and Opportunities. Feature Interactions in Telecommunications and Software Systems. Papers from the sixths International Workshop on Feature Interactions in Telecommunications and Software Systems May 2000. Edition: illustrated. Published by: IOS Press, 2000. ISBN   1-58603-065-5 ISBN   978-1-58603-065-0.
  2. ↑ http://www.3gpp.org/ftp/Specs/html-info/23228.htm
  3. ↑ Service-oriented Architecture Compass: Business Value, Planning, and Enterprise Roadmap. Author: Norbert Bieberstein, Sanjay Bose, Marc Fiammante, Keith Jones, Rawn Shah. Edition: illustrated. Published by: FT Press, 2005. ISBN   0-13-187002-5 ISBN   978-0-13-187002-4
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.