Question 24/XII - Integration of mobile systems into the public
switched network
(merging of Questions 24/XII and 33/XII. Continuation of Question 24/XII
studied during the 1984-88 study period, new wording)

Considering

(a) that the number of automatic land mobile and maritime mobile systems
connected (directly or through a national telephone network) to the
international telephone network, will increase;

(b) that speech processing equipment, such as automatic speech volume
control, companders, low-bit-rate coding, etc. used in some mobile
systems, may interact adversely with equipment in the international
telephone network;

(c) that for technical and economical reasons, mobile systems will not
conform to existing CCITT Recommendations;

(d) that existing CCITT Recommendations may be insufficient to ensure
satisfactory transmission quality of international connections including
mobile systems,

the following Questions should be studied:

1. What Recommendations should be given for

- loudness ratings;

- quantizing distortion;

- echo;

- one-way delay;

- stability;

for mobile systems?

2. What assessment method should be used and what values should be
recommended for noise in mobile systems?

3. Aspects on non-speech signal transmission.

4. Requirements of special service like roaming.

Note - A preliminary draft Recommendation G.173 is given in Supplement
No. 30, Volume III.1 of the Blue Book.
ANNEX 1

(to Question 24/XII)

Reply given to the Question in Report COM XII-R 30,
section 3.4, February 1988
ANNEX 2

(to Question 24/XII)

Reply given to Question 33/XII in Report COM XII-30,
section 9, February 1988

ANNEX 3

(to Question 24/XII)

Documentation received during the 1985-1988 period
1.COM XII-R 6-E, pages 8-19

2.COM XII-R 13-E, pages 9-14

3.COM XII-R 18-E, pages 11-15 and 106-108

4.COM XII-68 (European Joint Experts Group on low-bit-rate coding for
mobile radio)

Subjective testing methodology for the evaluation of low-bit-rate codes
for mobile radio.

5.COM XII-73 (British Telecom)

Delay aspects of low-bit-rate speech coding below 32 kbit/s

6.COM XII-79 (Norway)

Some considerations on medium-bit-rate speech coding for digital mobile
radio.

7.COM XII-94 (LM Ericsson)

Delay in low-bit-rate codecs.

8.COM XII-97 (British Telecom)

Considerations of echo caused by the acoustic loss path of telephone
sets.

9.COM XII-129 (Study Group XI)

Coordination of work on the mobile systems between CCITT Study Groups.

10.COM XII-134 (Study Group XV)

Reply from Working Party XV/2 to Working Party XII/3 on companders.

11.COM XII-147 (Swedish Administration)

Report on subjective test on candidate codecs for mobile radio.

12.COM XII-165 (Norway)

Assessment of talker echo caused by the acoustic echo-path in a 4-wire
telephone set. Results from a conversational experiment.

13.COM XII-183 (NTT)

Transmission speech quality in land mobile radio.