(Merging of Questions 16/12 and 17/12 studied in 1997-2000 study period)

Type of question

Task-oriented, leading to new and revised ITU-T Recommendations.

Background

ITU-T Recommendations have been a source for general transmission planning information for many years and these Recommendations have continued to be evolved, replaced or complemented to keep up with technological evolution. There is a continued need for this guidance, especially in light of the changes that have recently allowed competing carriers to provide service in any segment of a telecommunications connection. Increasingly, these segments involve technologies such as ATM, IP, Frame Relay, wireless, etc. These segments may include echo cancellers, automatic level control devices , or noise reduction devices that may interact with other network elements and cause transmission impairments. Additionally, due to factors such as mobility, the noise environment in which terminals are used is varying and may affect the performance of network elements. Thus, it is imperative that new guidance continues to be available.

The network will:

• involve new connection topologies;
• offer, on an ever increasing basis, connections comprised of mixed PSTN, ISDN, ATM and IP network segments;
• continue to use increasingly sophisticated digital processes (codecs, DCME, and packet voice, etc.) to increase connection efficiency;
• become more difficult to model because these new processes will introduce new impairments that will impact on the quality of the services carried on these connections;
• support an increasing number of sophisticated non-speech services that could be affected by the increased impairments.

Text of the question

Considering that a valid set of transmission planning guidelines should be available to network planners:

• Is a new approach to transmission planning required?
  The operating environment has changed to allow more liberalized competition and new connection topologies. The impact of this on the approach to transmission planning should be determined.
• What Hypothetical Reference Connections (HRC’s) are required to perform network transmission planning?
  The existing HRC’s in the G.100-Series Recommendations should be reviewed and harmonized as necessary. They should be complemented by new HRC’s, if required as a result of new connection topologies, especially those based on ATM and IP.
• Are different HRC’s required for different transmission parameters?
  In recognition of that fact that as connections increasingly use specialised digital processing, such as low bit rate coding used in wireless and IP systems, it may be necessary to develop HRC’s that apply to specific transmission impairments, such as delay, echo, distortion, packet loss, stationary or non-stationary noise, etc.
• What enhancements can be made to G.113 to improve its value to network planners, particularly in the area of providing guidance for non-speech services?
  The recent extensions of G.113 were focused on speech services while there was no advancements made in the area of nonspeech services.
• What guidance can be provided regarding talker and listener echo, transmission time and stability in evolving networks?

Study items

Main points of study are:

• determine if the new operating environment and the resultant new connection topologies require a new approach to transmission planning, and revise G.101 accordingly;
• determine what planning rules are required for multimedia services that incorporate a speech component;
• determine how frame slips, random bit errors, and packet loss should be incorporated into the transmission planning process for speech and non-speech signals;
• Recording, study and classification of stationary/non-stationary noise, that may lead to revise noise measures in P.561, and help producing a noise model to be included in the E-Model;
• performance requirements for noise reduction devices (new Recommendation G.1n1);
• determine the impairment effect of each new coding algorithm, so that it can be considered in the context of the G.113 planning Recommendation;
• determine the transmission delay of any new network technologies, so that it can be considered in the context of the G.114 planning Recommendation;
• determine if G.113 can be enhanced by its extension to include other impairment factors.

Objectives and schedules

Completion of G.1n1 by 2002.

Revision of G.101 by 2002.

Frequent updating of Appendix I to G.113.

Revise G.103, G.113 and G.114 as needed.

Relationship with other Study Groups

This Question should be studied in cooperation with ITU-T Study Groups 13, 15 and 16.