ITU Home Page International Telecommunication Union Franšais  Espa˝ol 
Print Version 
ITU Home Page
Home : ITU-T Home : Study Period 2001-2004
Question 18/15 - Characteristics of optical fibre submarine cable systems

(Continuation of Questions 18 and 19/15)

Background and justification

The demand for transmission capacity has been rapidly increasing due to the rapid evolution towards a packet based network infrastructure (Internet). Optical fibre submarine cable systems form an essential part of the worldwide communication networks and are affected by such an increase in demand. Transmission systems satisfying this demand could be realized using a combination of Time Division Multiplexing (TDM), wavelength division multiplexed (WDM), and optical amplifying techniques (in-line optical amplifier, post amplifier, pre-amplifier, remote amplification, etc.). Moreover, as the transmission capacity increases, protection mechanisms, both from a mechanical (submarine cables) and system perspective (e.g. ring structure), become more important to improve system reliability and availability.

Responsibility under this Question includes the following Recommendations:

G. 971: General features of optical fibre submarine cable systems

G. 972: Definition of terms relevant to optical fibre submarine cable systems

G. 973: Characteristics of repeaterless optical fibre submarine cable systems

G. 974: Characteristics of regenerative optical fibre submarine cable systems

G. 975: Forward error correction for submarine systems

G. 976: Test methods applicable to optical fibre submarine cable systems.

G. 977: Characteristics of optically amplified optical fibre submarine cable systems


  • How should Recommendations G. 971, G. 972, G. 973, G.975, G. 976 and G. 977 be amended or restructured in order to ease their use?
  • What new transmission techniques should be recommended to increase transmission capabilities of optical fibre submarine cable systems?
  • What new components and subsystems (fibre, component, etc.) should be utilized to improve system capacity and reliability?
  • What mechanical protection and system protection mechanisms should be recommended for high capacity submarine cable systems to improve systems reliability/availability?
  • What new Recommendations are necessary?

Study items

Study items to be considered include:

  • Transmission characteristics of optical fibre submarine cable systems
  • Interface characteristics of optical fibre submarine cable systems
  • Mechanical characteristics of the submarine portion of optical fibre submarine cable systems
  • Test methods
  • Evolution of submarine systems to higher bit-rates, including the effects of chromatic dispersion, polarization mode dispersion, and optical fibre nonlinearities
  • Adoption of wavelength-division multiplexing/ demultiplexing techniques
  • FEC (Forward Error Correction) for high bit rate DWDM submarine systems
  • Introduction of other types of fibre amplifiers or semiconductor amplifiers operating at different wavelengths
  • Use of branching devices in submarine networks
  • Availability and reliability
  • Operations and maintenance
  • Interface compatibility of submarine and terrestrial systems
  • Mechanical and systems level protection mechanisms
  • Optical submarine systems based on soliton transmission techniques

Specific tasks

  • Revision and/or restructuring G. 971, G. 972, G.973, G. 975, G. 976, and G.977 (2004)
  • Consider development of a new Recommendation to serve as a FEC standard for high bit rate DWDM submarine cable systems and in the same time keeping Rec. G.975 (Forward Error Correction for Submarine Systems) as reference for legacy submarine cable systems that use FEC code RS (225, 239) (2004)
  • Continue updating the Appendix/G. 971 regarding data on cable ships and submersible equipment (as required)


  • Other relevant Questions of SG 15 on optical transmission systems
  • ITU-T SG 6 on other types of underwater cables (e.g. marinized terrestrial cables)
  • ITU-T SG 13 on error performance
  • IEC SC86 on fibre reliability and on underwater cables


Top - Feedback - Contact Us - Copyright ę ITU 2004 All Rights Reserved
Contact for this page : TSB EDH
Updated : 2004-10-21