Question 16/XV - Characteristics of digital line systems for use in
local networks including narrow-band and broadband ISDN access
(Continuation of Question 25/XV 1985-88)

Considering

(1) that Recommendation G.961 specifies the digital line systems on
metallic pairs for basic rate access to ISDN;

(2) that Study Group XVIII has specified the basic requirements for
primary rate access;

(3) the increasing need for distributive broadband services such as
television and sound programme;

(4) the future need for interactive broadband services such as visual
telephony and videoconferencing;

(5) that the preliminary requirements for ISDN services have been
established;

(6) the functional characteristics and reference configuration for
broadband ISDN are being defined by Study Group XVIII;

(7) that the general network aspects such as network structure,
reference configurations, network performance objectives, etc. will be
further studied by Study Group XVIII;

(8) the possibilities offered by digital techniques and optical fibres
etc. for the transmission of digital signals in local networks;

(9) that the impact of private networks which include elements of public
networks need to be taken into account;

(10) that Recommendation G.960 specifies digital section for basic rate
access and that specific digital line sections may require further work;

(11) that a new synchronous digital hierarchy is under study in Study
Group XVIII,

1. What characteristics should be recommended for digital line systems
on optical fibre cables to be used in local networks including narrow-
band and broadband ISDN access?

2. What characteristics should be recommended for any optical interfaces
in local networks?

Points for study

1.Transmission media, e.g. fibre type.

2. Transmission method.

3. Transmission path interfaces.

4. Error performance.

5. Jitter performance.

6. Availability.

7. Reliability.

8. Environmental conditions, if some other studies appear necessary.

9. Maintenance strategy.

10. Monitoring capabilities.

11.Application of Operations, Administration and Maintenance interfaces
as given in Recommendation G.771 - any unique features required.

12.Protection against interference.

Notes

1. Account should be taken of the study of ISDN carried out by Study
Group XVIII including any access bit rates and other characteristics
that may be recommended by them for the local network.

2. The study of this Question should be coordinated with the study of
Questions 14/XV, 15/XV, 17/XV, 18/XV, 25/XV.

3. Operations, Administration and Maintenance interfaces on transmission
equipment are studied under Question 9/XV.

4. Study Group V is responsible for the study of protection against
dangers and disturbances of electromagnetic origin.

5.Study Group XVIII is responsible for general network issues.

6. Study on digital sections, if any, should be carried out under this
Question and coordinated with the studies on systems of CCIR Study
Groups 4 and 9.

7. Studies of this Question should be coordinated with Question
20/XVIII.