(Continuation and extension of Question 15/12 studied in 1997-2000)

Type

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

Background

Signal processing technology applied to both directions of transmission in a 4-wire path, can be used to estimate the contribution of a number of factors affecting the transmission performance of the complete connection, without interfering with the signals on the connection;

Desirable voice service measurements can be found in ITU-T Recommendation P.561, and guidance for the analysis and the interpretation of the measurement results can be found in ITU-T Recommendation P.562.

A device that performs such measurements is known as an In-service Non-intrusive Measurement Device (INMD).

As far as packetized systems (and more generally, non linear systems) are concerned, they are theoretically covered in P.561 by class D devices. The section of P.561 on those devices was left for further study during the last study period. New documentation and study results, as well as the evolution of network technologies (including interworking between, circuit switched, and packet switched mobile of fix networks), show that the time has come to think of an update of existing Recommendations on INMDs to take into consideration new systems like IP network equipments.

The parameters that can be added to existing INMD parameters include:

• non linear distortion,
• packet protocol parameters like latency, jitter and packet loss.

Text of the Question

1 What changes and/or improvements can be made to ITU-T Recommendations P.561 and P.562 to take into consideration new impairments generated in non-linear systems and how can measurements be made at the IP as well as other layers?

2 What relationship exists between the subjective responses of users at the terminals and the objective measurements made from the point at which the non-intrusive assessment system is connected ?

3 What measures give an estimate of the transmission quality of a connection including the accumulated effects of all technologies (e.g. IP, wireless, ATM, etc.)?

4 How can such measures be used to assess, plan and maintain the transmission quality of networks ?

5 How are non-intrusive measurements related to conventional intrusive measurements ?

Objectives and Schedule

Revised Recommendation P.561 by 2002 and P.562 by 2003.

New draft Recommendation on non-intrusive measurement of speech quality including audio parameters by 2004.

Relationship with other Study Groups and Questions

Liaison should be maintained with ITU-T Study Group 2 who deal with Quality of Service (QoS), ITU-T Study Group 4 whose responsibility is maintenance of networks, and ITU-T Study Group 13 which is the leading study group for internet protocol topics.

The work under other standardisation bodies, like ETSI (STQ, TIPHON) or IETF (IPPM), can also be useful for this new question.

The studies of Q.16 will also be fed by results coming from Q. 8, 9 (WP2) and 12 (WP3) of SG 12.