3.1 Overall Loss/Loudness ratings

3GPP43.050Release 17Transmission planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) systemTS

The overall international connection involving PLMNs and the PSTN should meet the overall loudness rating (OLR) limits in ITU‑T Recommendation G.111. The national parts of the connection should therefore meet the send and receive loudness rating (SLR, RLR) limits in ITU‑T Recommendation G.121.

For the case where digital routeings are used to connect the PLMN to the international chain of circuits, the SLR and RLR of the national extension will be largely determined by the SLR and RLR of the PLMN. The limits given below are consistent with the national extension limits and long term objectives in CCITT Recommendation G.121.

The SLR and RLR values for the PLMN apply up to the POI. However, the main determining factors are the characteristics of the MS, including the analogue to digital conversion (ADC) and digital to analogue conversion (DAC). Hence, in practice, it will be convenient to specify loudness ratings to the Air Interface. For the normal case, where the PLMN introduces no additional loss between the Air Interface and the POI, the loudness ratings to the PSTN boundary (POI) will be the same as the loudness ratings measured at the Air Interface. However, in some cases loss adjustment may be needed for interworking situations in individual countries.

These values are directly applicable to the case of an MS operating in a conventional non‑mobile noise environment. Studies have shown that under the PLMN noise environment, speech levels are likely to be higher. Hence, in order to avoid clipping in the speech transcoder, the value of SLR may need to be increased.

NOTE: In [51] 3GPP TS 51.010, measurement of SLR and RLR for handset MS is specified using sinusoidal test frequencies. This may not be the optimum method of measuring the loudness ratings because of the adaptive characteristics of the GSM speech transcoders. However the actual measurement is only performed over the linear portion of the MS. When developing the subsequent test methods for handsfree MS, in annex B and annex C, it was decided to use the artificial voice described in ITU‑T Recommendation P.50, to measure send and receive sensitivities.

3.1.1 Connections with handset MSs

Overall Loss/Loudness ratings shall be as specified in [49], 3GPP TS 26.131.

For a dual mode GSM/3GPP telephone compliance shall be checked according to the procedures described in [50] , 3GPP TS 26.132.

For a single mode GSM MS conformance shall be checked according to either the procedures described in [51] 3GPP TS 51.010 or the procedures described in [50] 3GPP TS 26.132.

3.1.2 Connections with handsfree MSs

Overall Loss/Loudness ratings shall be as specified in [49], 3GPP TS 26.131.

For a dual mode GSM/3GPP telephone as well as a single mode GSM MS compliance shall be checked according to the procedures described in [50] , 3GPP TS 26.132.

3.1.3 Connections with headset MSs

Overall Loss/Loudness ratings shall be as specified in [49], 3GPP TS 26.131.

For a dual mode GSM/3GPP telephone as well as a single mode GSM MS compliance shall be checked according to the procedures described in [50] , 3GPP TS 26.132.