1. Lecture 11 B-ISDN

2. Broadband ISDN In 1988, CCITT issued the first two recommendations relating to the broadband ISDN called B-ISDN. This system is defined as a service requiring transmission channels capable of supporting the rates greater than the primary rates. With B-ISDN, services such as video services which require very high data rates can become available.

3. Bit Rates for Different Applications

4. B-ISDN Services

5. Services of b-isdn P 493, f2e

6. Architecture of B-ISDN B-ISDN differs from the narrowband ISDN in different ways. In order to meet the requirement of high resolution video, an upper channel rate of the order of 150 Mbps is required. In order to support one or more interactive services and distribution, a total subscriber line rate of about 600 Mbps is needed. Such high data rates can be supported only by using the optical fiber. Hence B-ISDN depends completely on the development of optical fiber.

7. Internally, it is necessary to use a switching technique, which is capable of handling a wide range of different bit rates and traffic parameters. The best suitable switching technique used is called ATM. It is used at the user-network interface.

8. Functional Architecture off B-ISDN Figure: Functional architecture of B-ISDN

9. Functional Architecture The functional architecture of B-ISDN is shown in Fig. 6.17.1. Similar to the narrowband ISDN, control of B-ISDN is based on common channel signaling. B-ISDN supports all the 64 kbps transmission services, both circuit switching and packet switching which are present in the narrowband ISDN. In addition to these, B-ISDN also provides the broadband capabilities for higher data rate transmission. At the user network interface, these capabilities will be provided with the connection oriented asynchronous transfer mode (ATM) facility.

10. Fig. 6.17.1 clearly indicates that the reference configuration defined for the narrowband ISDN is being used for the B-ISDN as well.

11. Access Methods 155.520 Mbps Full Duplex – Three new transmission services are defined in terms of the data rates available to B-ISDN subscribers. The first one consists of a fully duplex 155.52 Mbps service. 155.520/622.080 Mbps Input – The second service is asymmetrical. It provides transmission from the subscriber to the network at 155252 Mbps and in the other direction at 622.08 Mbps. The third service is of the highest capacity which is a full duplex 622.08 Mbps service.

12. The data rate of 155.52 Mbps can support most of the B-ISDN services. At this rate it is possible to transmit one or more video channels. Hence the full duplex 155.52 Mbps service will be the most common B-ISDN service. The higher data rate of 622.08 Mbps is required for transmitting multiple video distributions such as multiple simultaneous video conferences.

13. 622.080 Mbps Full Duplex

14. B-ISDN Accesses

15. B-ISDN Protocols 6.17.3, P 6-40, K

16. Advantages of B-ISDN P 6-41, K