Broadband ISDN
The broadband ISDN ( B-ISDN ) should on user channels with low data transfer rate anabolic ISDN (narrowband ISDN English. Narrowband ISDN supplement). The intention was to provide the user with higher data transfer rates with B-ISDN.
Transmission technology
Narrowband ISDN is based on PCM technology with 64 kbit / s channels; Subscriber connections are made using a basic connection with two channels or as a primary rate connection with 30 channels. The planning for B-ISDN saw as transmission techniques
- the Asynchronous Transfer Mode (ATM) and
- the Synchronous Digital Hierarchy (SDH).
Pilot tests
The B-ISDN in its original conception did not get beyond pilot tests . These pilot tests enabled the participants to have a maximum data transmission rate of 155 Mbit / s; the next stage was 622 Mbit / s. The planned network topology of the B-ISDN would have corresponded to the ISDN: Central switching centers in a hierarchical star network with meshing. One of the original basic ideas was that the growing ISDN traffic should also be transferred to the B-ISDN using concentrators and multiplexers .
Possible broadband services
For example, the following applications were intended for the B-ISDN:
- Moving image communication: videophone , video conference , video surveillance
- Data communication: LAN connections, CAD / CAM connections, data transfer
- Exchange of messages: video e-mail, multimedia documents
- On-demand services: distance learning , databases
- News on demand : video on demand , distribution services, radio and television , electronic newspaper
The integrated broadband telecommunications network was conceived as an even more advanced technology in the 1980s . While B-ISDN was only supposed to expand the narrowband ISDN to include the broadband services of individual communication video telephony , mass media broadband distribution services for television and radio as a broadband distribution network were also planned for IBFN .
Access network
In addition to newly laid fiber-optic cables , the access network should also use technologies that use existing telephone and cable networks . These technologies include the following:
- High Data Rate Digital Subscriber Line (HDSL): Several copper wire pairs can be bundled to achieve data transfer rates of up to 20 Mbit / s in both directions.
- Asymmetric Digital Subscriber Line (ADSL): On a subscriber line can be achieved in a direction s to 12 Mbit / s.
Current status
The terms B-ISDN or broadband ISDN are no longer used for today's broadband networks. The main reason for this is that the network design of the B-ISDN proved to be too expensive: IP - routers are cheaper than ATM switching centers . Furthermore, the connection-oriented B-ISDN, compared to the connectionless IP networks, would be significantly less suitable for the applications that are predominant on the Internet today , such as the World Wide Web . The public broadband networks still use ATM in the backbone area today, but only as a transport infrastructure.
Standards
- ITU-T I.121, Broadband aspects of ISDN, 04-1991
- ITU-T I.311, B-ISDN general network aspects, 08-1996
- ITU-T E.737, Dimensioning methods for B-ISDN, 02-2001
Individual evidence
- ↑ a b c Technology of Networks, Gerd Siegmund, Hüthig, 5th edition 2002
- ↑ ITU-T I.430 Integrated Services Digital Network (ISDN) - Basic Rate User-Network Interface - Layer 1 Specification
- ↑ ITU-T I.431 Integrated Services Digital Network (ISDN) - Primary Rate User-Network Interface - Layer 1 Specification
- ↑ Barbara Mettler-Meibom : Broadband technology: About the chances of social reason in technology-political decision-making processes. Volume 79 of contributions to social science research. Springer-Verlag, 2013. ISBN 3322886859 , ISBN 9783322886859 (Online at Google Books, p. 78)