Question 29/XV - Characteristics of digital systems on optical fibre
cables for the synchronous hierarchy

Considering

(1) that a number of Recommendations in the G.700-Series gives
characteristics on Network Node Interfaces (NNI) and on the synchronous
digital hierarchy;

(2) that there is a need for new generations of digital systems on
optical fibres based on this synchronous hierarchy;

(3) that optical fibres may be used for in-station cabling,

1. What new Recommendations should be established regarding digital
systems on optical fibre cables based on the new synchronous digital
hierarchy?

2. What line interface requirements should be recommended to ensure the
transverse compatibility of these systems (i.e. the possibility of
mixing various manufacturers' equipment within a single digital line
system)?

3. What should be the characteristics of related optical fibre in-
station cabling systems?

4. How should other existing Recommendations in the G.900-Series be
amended and completed in so far as they relate to systems addressed by
this Question?

Points for study

1.Systems at bit rate related to the synchronous hierarchy.

2.Attenuation and/or dispersion limited systems.

3.Single-mode fibre systems employing LEDs, multilongitudinal-mode
lasers (MLM-LD) and single longitudinal-mode lasers (SLM-LD).

4.Systems not optimized for maximum section length.

5.Wavelength division multiplexing.

6.Systems employing coherent detection.

7.Possible power supply arrangements and related precautions against
induced voltages and currents.

8.Environmental conditions.

9.Overall design features.

10.Implications of IEC studies of optical fibre/laser safety
considerations.

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

12.Design methodology - worst case versus statistical design approach.

13.Definitions and test methods of system/equipment parameters.

14.Error performance.

15.Requirements for systems/equipment characteristics which provide
transverse compatibility in order to enable equipments designed by
different manufacturers to interwork and/or be utilized together in a
given digital line system (i.e. the possibility of mixing various
manufacturers' equipment within a single digital line system) including
optical pulse shape and optical source parameters.

16.The requirements for systems operating on fibres conforming to
Recommendations G.651, G.652, G.653 and G.654.

17.The use of optical fibre systems for in-station cabling.

18.Maintenance strategy:

18.1 monitors and alarms,

18.2 supervision and fault location,

18.3 protection switching.

Notes

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

2.Protection switching systems are studied under Questions 5/XV and
6/XV.
3. The study of this Question should be coordinated with the study of
Questions 11/XV, 12/XV, 13/XV, 15/XV, 18/XV, 19/XV and 25/XV.

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

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