5.7 Echo Control

26.1313GPPRelease 17RequirementsTerminal acoustic characteristics for telephonyTS

5.7.1 General

The echo loss (EL) presented by the 3G, LTE, NR or WLAN network at the POI should be sufficient during single-talk. This takes into account the fact that the UE is likely to be used in connections with high transmission delay and in a wide range of noise environments.
See ITU-T Recommendation G.131 for general guidance.

The use of acoustic echo control is not mandated for 3G, LTE, NR or WLAN networks and the connection between the UE and the POI is zero loss. Therefore the acoustic echo control provided in the UE should provide a sufficient TCLw at the POI over the likely range of acoustic end delays.

If acoustic echo control is provided by voice switching, comfort noise should be injected. This comfort noise shall operate in the same way as that used in DTX.

5.7.2 Acoustic echo control in desktop and vehicle-mounted hands-free UE

The TCLw for the desktop and vehicle-mounted hands-free UE shall be ≥ 40 dB for any setting of the volume control.

The TCLw for the desktop hands-free and vehicle-mounted hands-free UE shall be ≥ 46 dB when measured under free-field conditions at the nominal setting of the volume control.

NOTE: A TCLw for the desktop hands-free and vehicle-mounted hands-free UE of ≥ 55 dB is recommended as a performance objective when measured under free-field conditions at the nominal setting of the volume control. Depending on the UE idle channel noise in the sending direction, it may not always be possible to measure an echo loss ≥ 55 dB.

The echo canceller should be designed to cope with the expected reverberation and dispersion. In the case of the hands-free UE, this reverberation and dispersion may be time variant. Compliance with this requirement shall be checked by the relevant test described in TS 26.132.

5.7.3 Acoustic echo control in hand-held hands-free UE

The TCLw for hand-held hands-free UE shall be ≥ 40 dB for any setting of the volume control.

The TCLw for hand-held hands-free UE shall be ≥ 46 dB at the nominal setting of the volume control.

NOTE: A TCLw for the hand-held hands-free UE of ≥ 55 dB is recommended as a performance objective when measured under free-field conditions at the nominal setting of the volume control. Depending on the UE idle channel noise in the sending direction, it may not always be possible to measure an echo loss ≥ 55 dB.

The echo canceller should be designed to cope with the expected reverberation and dispersion. In the case of the hands-free UE, this reverberation and dispersion may be time variant. Compliance with this requirement shall be checked by the relevant test described in TS 26.132.

5.7.4 Acoustic echo control in a handset UE

The TCLw for handset UE shall be ≥ 46 dB for any setting of the volume control.

The TCLw for handset UE should be ≥ 55 dB at the nominal setting of the volume control.

NOTE: It is recommended that the volume control should be set back to nominal after each call unless TCLw ≥ 55 dB can also be maintained with the maximum volume setting. Depending on the UE idle channel noise in the sending direction, it may not always be possible to measure an echo loss ≥ 55 dB.

The echo canceller should be capable of dealing with the variations in handset positions when in normal use. The implications of this are under study. Compliance with this requirement shall be checked by the relevant test described in TS 26.132.

5.7.5 Acoustic echo control in a headset UE

The TCLw for headset UE shall be ≥ 46 dB for any setting of the volume control.

The TCLw for headset UE should be ≥ 55 dB at the nominal setting of the volume control.

NOTE: It is recommended that the volume control should be set back to nominal after each call unless TCLw ≥ 55 dB can also be maintained with the maximum volume setting. Depending on the UE idle channel noise in the sending direction, it may not always be possible to measure an echo loss ≥ 55 dB.

The echo canceller should be designed to cope with the expected reverberation and dispersion.

Compliance with this requirement shall be checked by the relevant test described in TS 26.132.

5.7.6 Echo control in an electrical interface UE

The TCLw for electrical interface UE shall be ≥ 46 dB for any setting of the volume control.

The TCLw for electrical interface UE should be ≥ 55 dB at the nominal setting of the volume control.

NOTE: It is recommended that the volume control should be set back to nominal after each call unless TCLw ≥ 55 dB can also be maintained with the maximum volume setting. Depending on the UE idle channel noise in the sending direction, it may not always be possible to measure an echo loss ≥ 55 dB.

The echo canceller should be designed to cope with the expected reverberation and dispersion.

Compliance with this requirement shall be checked by the relevant test described in TS 26.132.