6 Example solution

3GPP46.011Full rate speechRelease 17Substitution and muting of lost frames for full rate speech channelsTS

For guidance, an example solution is given.

The first lost speech frame is replaced at the speech decoder input by the previous good speech frame. Normal decoding is then performed.

The muting procedure to be used in the case of subsequent lost speech frames or for comfort noise frames following the second lost SID frame is as follows:

The pseudo‑logarithmic encoded block amplitude Xmaxcr (GSM 06.10 [2]), coded on the interval from 0 to 63, is decreased with a constant value d=4 in each frame, down to the lowest possible value. Consequently, Xmaxcr will be reduced gradually, and the output muted after a maximum of 320 ms. The grid position parameters are chosen randomly between 0 and 3 during this time.

For subsequent unusable frames, after the frame where Xmaxcr reached the lowest possible value, "silence frames" are passed from the RX DTX handler to the speech decoder to guarantee a low output level under all conditions. The silence frame is defined in table 1.

Table 1: Encoded parameters (GSM 06.10) of the silence frame

Log area ratio 1 = 42

Log area ratio 2 = 39

Log area ratio 3 = 21

Log area ratio 4 = 10

Log area ratio 5 = 9

Log area ratio 6 = 4

Log area ratio 7 = 3

Log area ratio 8 = 2

_

LTP gain = 0

LTP lag = 40

Grid position = 1

Block amplitude = 0

RPE pulse no. 1 = 3

RPE pulse no. 2 = 4

RPE pulse no. 3 = 3

RPE pulse no. 4 = 4

RPE pulse no. 5 = 4

‑ repeated for each subsegment

RPE pulse no. 6 = 3

RPE pulse no. 7 = 3

RPE pulse no. 8 = 3

RPE pulse no. 9 = 3

RPE pulse no. 10 = 4

RPE pulse no. 11 = 4

RPE pulse no. 12 = 3

RPE pulse no. 13 = 3 _

Annex A (informative):
Change history

Change history

SMG No.

TDoc. No.

CR. No.

Section affected

New version

Subject/Comments

SMG#07

4.0.4

ETSI Publication

SMG#20

5.0.1

Release 1996 version

SMG#27

6.0.0

Release 1997 version

SMG#28

6.0.1

ETSI Publication

SMG#29

7.0.0

Specification version 6.0.0 upgrade to Release 1998 version 7.0.0

7.0.1

Version update for Publication

SMG#31

8.0.0

Release 1999 version

Change history

Date

TSG #

TSG Doc.

CR

Rev

Subject/Comment

Old

New

03-2001

11

Version for Release 4

4.0.0

06-2002

16

Version for Release 5

4.0.0

5.0.0

12-2004

26

Version for Release 6

5.0.0

6.0.0

06-2007

36

Version for Release 7

6.0.0

7.0.0

12-2008

42

Version for Release 8

7.0.0

8.0.0

12-2009

46

Version for Release 9

8.0.0

9.0.0

03-2011

51

Version for Release 10

9.0.0

10.0.0

09-2012

57

Version for Release 11

10.0.0

11.0.0

09-2014

65

Version for Release 12

11.0.0

12.0.0

12-2015

70

Version for Release 13

12.0.0

13.0.0

Change history

Date

Meeting

TDoc

CR

Rev

Cat

Subject/Comment

New version

03-2017

SA#75

Version for Release 14

14.0.0

06-2018

SA#80

Version for Release 15

15.0.0

2020-07

Update to Rel-16 version (MCC)

16.0.0

2022-04

Update to Rel-17 version (MCC)

17.0.0