Next generation network

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Next Generation Network ( NGN ), also called Next Generation Access Network ( NGA-Netz ), describes the network technology in telecommunications which replaces traditional circuit-switching telecommunications networks such as telephone networks , cable television networks , cellular networks , etc. with a uniform packet-switching network infrastructure and architecture and replaces the older ones Telecommunication networks is compatible. The designation NGN / NGA is also used (in a simplistic way) as a catchphrase for the current conversion of the existing telecommunication networks to Internet protocol technology (IP), since the Internet protocol is the predominant choice for the implementation of packet-switching networks.

The advantage is convergence . One of the essential features of NGN is that different network functions such as transport, service and the control function (e.g. signaling) are implemented on different (logical) network levels.

Critics see NGNs as a threat to net neutrality . In particular, reference is made to the planned introduction of the defined end-to-end quality of service ( QoS ) and the associated possibility of deliberately "slowing down" or even blocking data streams .

background

motivation

Due to the increasing cost pressure in the telecommunications market and the drop in prices for voice services, the service providers and network operators are forced to look for new approaches to the economical and efficient offer of telecommunications services and the operation of telecommunications networks. So far, the telecommunications market has been dominated by traditional telephony providers. However, there is an increasing convergence of services and networks. Classic portal providers such as B. Google , Yahoo , MSN or cable network operators on this market. The increasing range of telephone services using IP telephony (VoIP) is just one example. In the course of this convergence, the value contribution of the network provision in the end customer sales decreases in favor of the service offer; the value chains of the telecommunications market are changing. The established network operators are therefore forced to look for potential cost savings and rethink their business models. Due to the convergence of four industries T elecommunications, I nformation, M edia and E ntertainment has emerged as collective term the acronym TIME established.

The traditional telecommunications infrastructure is structured heterogeneously . Fixed line telephony and data transmission are implemented using different technologies. There are direct dependencies between services and the technology used, which means that the introduction of new services by adapting the hardware is a very costly and lengthy process. A uniform network infrastructure that can be used as a platform for offering all services would save time and money. In addition, the restriction to only one system technology offers great savings potential in terms of costs for maintenance, conversion and procurement as well as the reduction in the number of technical locations and areas. The conversion of the previous circuit-switching networks to packet-switching networks using the Internet Protocol is seen as a fundamental possibility .

It should also be noted that the infrastructure cannot be switched to packet switching suddenly, but that the existing telephone networks and network access with the corresponding connected end devices must be operated in parallel with the new network structures for a longer period of time. A trouble-free migration process must therefore be guaranteed. Therefore, the new network infrastructure must be a PSTN / ISDN - simulation and - Emulation allow.

Against this background, the need is seen to develop a comprehensive network architecture that provides control mechanisms with the help of which the network resources can be sensibly controlled and managed according to the requirements of the services and the number of users. The aim of the NGN development is to meet these requirements.

Historical development

The first NGN specifications for the European region took place in ETSI Project TIPHON ( T elecommunications and I nternet P rotocol H armonization O ver N etworks). By combining this project with the ETSI TC SPAN ( T echnical C ommittee S ervices and P rotocols for A dvanced N etworks) was then the ETSI TC TISPAN ( T elecoms & I nternet converged S ervices & P rotocols for A dvanced N etworks) founded, which is responsible for the processing of standards for NGN within ETSI to this day.

The work in ETSI TC TISPAN takes place against the background of the creation of concepts for the migration from PSTN / ISDN to packet-switching networks. An NGN was specified that can switch on and replace PSTN and ISDN . All system components are provided, in particular to implement voice transmission services in an NGN. Protocols and mechanisms are specified by the TISPAN working groups in order to help network operators develop migration strategies in order to be able to fall back on standardized components.

In addition, there is the 3rd Generation Partnership Project (3GPP) , which is developing an NGN from UMTS and is thus being advanced by the mobile network operators. 3GPP has developed the core specification of IP Multimedia Subsystem (IMS) based on IP technology. Both groups, ETSI TC TISPAN and 3GPP, aim to implement NGN on the basis of IMS. ETSI TISPAN and 3GPP work closely together to prevent the IMS specifications from diverging.

Within the ITU, comparable work began in 1995 with the Global Information Infrastructures (GII) project, which then led to the specification of the ITU-T-NGN. The ITU-T approach is an overarching model for the long-term and complete replacement of circuit-switched networks by packet-switched networks with a focus on defining the basic functions and architecture, while the work at ETSI focuses more on the elaboration of practical implementations. ETSI TISPAN tries to ensure the compatibility of ITU-T and its own approach through a close exchange with ITU-T.

NGN Timeline.png

Definition and specification

Definition of the ITU

The ITU-T defines an NGN in the ITU-T recommendation Y.2001 as follows (translation from English):

“A next generation network (NGN) is a packet-switched telecommunications network that provides telecommunications services, uses many broadband, quality-of-service transport technologies and in which service-related functions are independent of the transport technology used. It offers users unrestricted access to networks, competing service providers and / or services of their choice. It supports general mobility, which enables constant and ubiquitous provision of services to users. "

The concept of general mobility plays a fundamental role in the NGN and is therefore defined more precisely in the ITU-T recommendation Y.2001 (translation from English):

“The ability of users or other mobile devices to communicate and gain access to telecommunications services, regardless of changes in their location or the technical environment. The level of service availability can depend on various factors, including the characteristics of the access network, the service contracts between the user's “home network operator” and those of the “network operator” visited (if applicable), etc. Mobility includes the possibility of telecommunication with or without maintaining the service (service continuity). "

Furthermore, the ITU-T recommendation Y.2001 lists the following fourteen basic characteristics that must be fulfilled in order for a telecommunications network to be regarded as an NGN:

  1. Packet transfer
  2. Division of the control functions into transmission properties, call / connection and application / service
  3. Decoupling of the range of services from the network and provision of open interfaces
  4. Support of a wide range of services, applications and mechanisms based on service building blocks (service modules) (including real-time / streaming / non-real-time services and multimedia)
  5. Broadband capabilities with consistent quality of service and transparency
  6. Cooperation with existing networks via open interfaces
  7. General mobility
  8. Unrestricted access for users to various service providers
  9. Variety of identification schemes
  10. Uniform service features for the same service from the user's point of view
  11. Convergence of services between fixed / mobile
  12. Independence of service-related functions from the underlying transportation technologies
  13. Support of various last mile technologies
  14. Compliance with all regulatory requirements, e.g. B. Emergency communications and security / confidentiality, etc.

The concept of the ETSI working group TIPHON

This ETSI working group was founded in 1997 and has meanwhile been discontinued in favor of ETSI AG TISPAN. The concept essentially consists of the following components:

  • Media gateways that physically connect the individual networks and ensure the transmission of information - including the necessary format and data conversion, and
  • Soft switches that control the media gateways and, for example, establish and clear connections across all network boundaries.

New services in an NGN are also referred to as NGS ( Next Generation Services ). These services are provided by the so-called Service Delivery Platform (SDP).

The IMS of 3GPP

IMS is being developed in Europe by 3GPP , an association of operators and manufacturers in the field of mobile communications. With Release 5 of its “Technical Recommendations (TR)” an “all IP” concept is introduced.

The concept comprises three layers, the "Transport Layer" of the ITU approach is split into "Transport Layer" and "IMS Layer". The functionality is distributed as follows:

  • The transport layer comprises the gateways and integrates the access networks
  • The IMS layer includes the "Call Control" function (CSCF), as well as control functions for the gateways
  • the service layer contains the HSS (database) and AS (application server)

A detailed description and sources can be found in IP Multimedia Subsystem .

The concept of the ETSI working group TISPAN

The ETSI TISPAN NGN is specified in Release 2. The concept takes IMS as its starting point (“Core IMS”) and does not integrate mobile-specific forms of access. The following are mentioned in particular:

The basic architecture is defined in the ETSI specification ES 282 001.

ETSI distinguishes between two functional groups:

  • Transport Stratum
  • Service stratum

The applications are counted here in the service layer. We speak of (logical) functions, how their technical realization is not part of the specifications. The terms have nothing to do with the similar ones in the OSI model .

Transport layer

The transport layer comprises the “Transport processing functions”, the “Network Attachment Subsystem” (NASS) and the Resource and Admission Control Subsystem (RACS). The transport processing functions (called transfer functions in Release 1) connect the NGN system to the networks to be served. This also includes signaling and media gateways. The NASS and the RACS contain the control functions and services of the transport layer . These include in particular IP address management, IP-based access control (both NASS), resource management and NAT support (both RACS).

Service layer

The "Core" IP Multimedia Subsystem (IMS) is the central component of the NGN architecture. It implements a SIP IMS switch to control all SIP multimedia services. It supports the IMS based PSTN / ISDN emulation system.

The PSTN / ISDN emulation subsystem (PES) makes it possible to emulate PSTN or ISDN services and thus to connect traditional telephony devices to the NGN. The PES distinguishes between two approaches: the softswitch-based approach and the IMS-based approach.

The The IPTV subsystem specifies the integration of IPTV and similar services in the NGN.

The common components are a set of functions that are shared by the above-mentioned functions of the service layer. This includes in particular interfaces for database access (User Profile Server Function and Subscription Locator Function) and for access to the applications (Application Server Function (ASF))

Three interfaces are defined for the Application Server Function (ASF) :

  • SIP Application Servers (SIP AS) for connecting applications that can handle SIP
  • the IM-SSF Application Server for connection to IN applications with CAMEL or ETSI Core INAP interfaces
  • OSA SCS Application Server for connection to IN applications with OSA / Parlay interfaces

ETSI TISPAN does not currently specify any applications. Examples of applications are given in the literature.

End-to-end quality of service

A general problem arises from the simultaneous use of the same network for the transmission of voice and data. An increased data traffic would increase the latency of the voice transmission, which is perceived as annoying by the conversation partners. The organizations involved in the definition of the NGN concept see measures to achieve “broadband capability with defined end-to-end quality of service (QoS)” as necessary, which should achieve “first-line quality” comparable to the fixed network . This is u. a. in Internet forums repeatedly the subject of discussions, since the OSI model typical of the Internet requires a more complex system of different hardware and software components for data transport than the ISDN-based analog or digital technology in the conventional fixed network .

See also quality features in IP telephony

Power requirements for the end user

The use of a modem with a router for a Next Generation Network (NGN) and a built-in analog telephone adapter can result in significant electrical output. The modems (Residential Gateways (RGW)) from the manufacturer Standard Microsystems Corporation (SMC) sold by Arcor are to serve as an example : According to the nameplate, the type A400 is specified with 15 watts, the type A401 and A601 with 18 watts each. In the case of POTS and ISDN connections that are connected to an Access Gateway (AGW) at the network operator, however, the end user does not need any different power requirements than the traditional telephone connection.

operating cost

Because of the uninterrupted operation required for the telephone adapter, the consumption and costs for routers from Arcor / Vodafone are exemplary

  • A400 with 15 watt connected load: 131.4 kWh / a; with 0.28 € / kWh operating costs are 36.79 € / a
  • A401, A601 with 18 watt connected load: 157.7 kWh / a; With 0.28 € / kWh, there are 44.16 € / a operating costs.

Emergency calls and emergency power supply

NGN connections have so-called first-line quality, a level of reliability comparable to that of conventional fixed-line networks. The power supply of the telephones remains a problem in the event of a failure or disruption of the public power grid. In contrast to the analog landline or ISDN connection, this is not the case with Voice over IP. Otherwise, emergency calls are possible without restriction. In addition, with Voice over Cable (VoC) , this configuration does not allow any technical emergency or remote supply , since the CMTS does not offer this standard function of the classic exchange in the DSL area. In addition, in the event of an emergency call, the caller can be located and the location information can be transmitted to the control center . All NGN connections thus comply with the requirements of the German Telecommunications Act . Regardless of the technology used, emergency calls will continue to be prioritized at the expense of other telephone calls in the event of network-side bottlenecks.

Making calls in the event of a power failure is problematic. Network providers are obliged to ensure emergency power supply, but this only applies to their own network infrastructure. By eliminating the analog in-band voice channel in favor of increased data rates with a full DSL connection - in contrast to analog telephones or ISDN - conventional telephones can no longer be operated with mains-side emergency power. A petition, which in 2016 called on the German Bundestag to oblige the network operators as legislators to provide emergency power supply to the customer's end device, had no effect. While analog connections, which are also migrated to IP solutions in the background, are supplied with emergency power for several hours in the event of a power failure, users of NGN connections are dependent on their own emergency power, for example on a power strip with an emergency power system or the use of a mobile phone . In both cases, operation is limited by the battery power. In the event of a large-scale blackout, about two hours of emergency power can be expected for mobile communications, but smaller base stations that only serve to optimize network coverage are shut down immediately. House emergency call systems contain a base station with an emergency power supply and a "GSM fallback", which means that mobile radio can be used as an alternative communication channel in an emergency.

Regardless of the network technology used, it must be taken into account that most end devices, such as cordless DECT devices , do not work without an external power source and are also dependent on emergency power.

criticism

Critics complain that the telephone service of NGN providers is again firmly linked to the broadband connection and that VoIP providers who have developed their products in the previous network-neutral Internet are excluded from the new networks. In addition, customers are largely forced to use NGN telephony, as the operator hardware does not allow the connected telephones to be used with another VoIP provider.

A major advantage of Voice over IP is that it can be used on the go. When traveling, VoIP customers can be reached on any broadband connection around the world using telephone software or VoIP-enabled mobile phones under their local number. Since the connection is registered in Germany, only the German tariff applies for calls to your home country. Next Generation Network does without this convenience and excludes nomadic use.

Due to the open standard, the SIP protocol used by VoIP providers and its possibilities are being further developed worldwide. The audio quality also benefits from this. Wideband codecs now allow a high-fidelity speech quality. The use is open to every customer of the alternative provider. NGN users, on the other hand, can only access the operator technology and therefore continue to make calls in fixed-line quality.

Another restriction is that NGN networks are exclusively geared towards voice transmission and possibly fax. This means that other services - such as card terminals for companies - are not possible. In contrast to conventional telephone connections, if the power supply fails, there is no emergency power supply (see # Emergency calls and emergency power supply ).

See also

Web links

Individual evidence

  1. ↑ www.bka.gv.at/Docs/2007/12/7/NGN.ppt ( Memento of the original from September 10, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. - NGN worksheet, which describes the possibility of a targeted lockout of Internet content. @1@ 2Template: Webachiv / IABot / www.bka.gv.at
  2. ↑ www.heise.de/ct/09/01/038/ ( Memento from December 22, 2008 in the Internet Archive ) - Heise. c't . 1/2009, p. 28: Net neutrality.
  3. ↑ ETSI TIPHON website .
  4. ↑ ETSI TISPAN website ( Memento of the original dated February 5, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.etsi.org
  5. ↑ ITU-T recommendation Y.2001 (12/04) .
  6. ↑ About 3GPP ( Memento of the original from May 10, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.3gpp.org
  7. ↑ TISPAN_NGN_2004.ppt Converged Fixed-Mobile solutions: The TISPAN_NGN approach (Powerpoint presentation) ( Memento of the original from July 12, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / portal.etsi.org
  8. ↑ ETSI ES 282 001: Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); NGN Functional Architecture.
  9. ↑ ETSI ES 282 001: Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); NGN Functional Architecture.
  10. ↑ ETSI ES 282 004: Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); NGN Functional Architecture; Network Attachment Sub-System (NASS).
  11. ↑ ETSI ES 282 003: Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Resource and Admission Control Sub-system (RACS); Functional architecture.
  12. ↑ ETSI ES 283 003: Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IP Multimedia Call Control Protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Stage 3.
  13. ↑ ETSI ES 282 002: Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); PSTN / ISDN Emulation Sub-system (PES); Functional architecture.
  14. ↑ ETSI TS 182 028: Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IPTV Architecture; Dedicated subsystem for IPTV functions.
  15. ↑ Electricity prices for private households .
  16. ↑ No emergency power supply at the cable connection (1) - Thread on power failure & emergency calls in the UMKBW forum ( memento of the original from August 16, 2017 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.unitymediakabelbwforum.de
  17. ↑ No emergency power supply at the cable connection (2) - Thread on power failure & emergency calls in the Helpdesk forum
  18. ↑ Bundestag: The emergency call must also work in the event of a power failure. Telariff, March 7, 2016
  19. ↑ Claudia Brüggen-Freye: Internet telephony: Who will help me in an emergency? Computer picture, November 26, 2017
  20. ↑ a b Home emergency call and IP telephony: Safe and reliable with Deutsche Telekom
  21. ↑ Cellular. tariftip.de, accessed on February 18, 2018
  22. ↑ Sipgate criticizes the new service wasteland with the NGN telephone connection , www.telefontarifrechner.de from May 13, 2008.