D.2 Half rate MS delay requirement definition

03.503GPPTransmission planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) systemTS

The symbol definitions for the calculations in this clause are:

Trftx: The time required for transmission of a TCH radio interface frame over the air interface due to the interleaving and de‑interleaving (system dependent).

Ttransc: The speech encoder processing time, from input of the last PCM sample to output of the final encoded bit (implementation dependent).

Tsample: The duration of the segment of PCM speech operated on by the speech transcoder.

Tencode: The time required for the channel encoder to perform channel encoding (implementation dependent).

Trxproc: The time required after reception over the air interface to perform equalization, channel decoding and SID frame detection (implementation dependent).

Tproc: The time required after reception of the first gain vector (GSPO) to process the speech encoded data for the half rate speech decoder and to produce the first PCM output sample (implementation dependent).

Ta/d: Delay in the analogue to digital converter in the downlink.

Tmargin: An allowance for system entities that are implementation dependent.

Td/a: Delay in the digital to analogue converter in the uplink.

Tpcm: The duration of a segment of PCM speech for the downlink processing delay.

The half rate MS speech delay in the uplink direction is the delay between an acoustic event at the MRP to the last bit of the corresponding speech frame at the antenna connector and shall not exceed:

MS uplink delay = Ta/d + Tmargin + Tsample + Ttransc + Tencode + Trftx

= 1,0 + 1,9 + 24,4 + 12,1 + 1,2 + 32,9 ms

= 73,5 ms

The half rate MS speech delay in the downlink direction is the delay between the first bit of a speech frame at the antenna connector and the last acoustic event at the ERP corresponding to that speech frame and shall not exceed:

MS downlink delay = Tpcm + Trftx + Trxproc + T proc + Tmargin + Td/a

= 24,4 + 32,9 + 8,8 + 1,9 + 1,9 + 0,5 ms

= 70,4 ms

The round trip delay shall therefore not exceed:

143,9 ms (see clause 3.3.6.2).

Annex E (informative):
Adaptive gain control

In noisy surroundings the speaker automatically raises his voice to compensate for the noise. The sending sensitivity can therefore be reduced, giving the same voice output to the line as under quiet conditions and at the same time reducing the output line noise level.

On the other hand the receiving sensitivity has to be increased under noisy conditions to give a better perceived sound quality.

The Sending and receiving sensitivities may be modified automatically by implementing an Adaptive gain control. The gain variation in the set corresponds to a gain in the receiving path and to a symmetrical attenuation in the sending path for increased ambient noise level.

The following table presents, for guidance and illustration only, three examples of gain variation characteristics.

Table E.1: Gain variation characteristics

Ambient noise level

Relative Gain variation

Single threshold

between –44 and –39 dBPa(A)

8 dB

Double

‑44 dBPa(A)

5 dB

threshold

‑34 dBPa(A)

10 dB

Continuous

from –64 to –44 dBPa(A)

3 dB

variation

from –44 to –24 dBPa(A)

8 dB

Annex F (informative):
Change Request History

SMG#

SPEC

CR

PHASE

VERS

NEW_VERS

SUBJECT

S17

03.50

A005

2+

5.0.0

New specification for handsfree performance

S17

03.50

A006

2+

5.0.0

Noise reduction Specification for the GSM MS.

S17

03.50

A007

2+

5.0.0

Inclusion of the possibility to use a type 3.2 leaky ear for handset tests.

S17

03.50

A008

2+

5.0.0

Update of references

s24

03.50

A011

R96

5.0.2

5.0.3

CR to 03.50 Correction of wrong reference to ITU-T Recommendation

s25

03.50

A013

R96

5.0.3

5.1.0

Removal of inconsistency in RLR for Handsetand Headset MS

s27

03.50

A014

R96

5.1.0

5.2.0

Correction of reference in Section 1.1

s27

03.50

6.0.0

Release 1997 version

s28

03.50

A018

R97

6.0.0

6.1.0

Acoustic testing of MS over the air interface

s29

03.50

7.0.0

Upgrade to Release 1998 version 7.0.0

03.50

7.0.0

7.0.1

Update to version 7.0.1 for Publication

s31

03.50

7.0.1

8.0.0

Release 1999 version 8.0.0

s32

03.50

A022

R99

8.0.0

8.1.0

Addition of a new optional artificial ear Type for acoustic tests

03.50

8.1.0

8.1.1

Update to Version 8.1.1 for Publication