5.13 Echo control characteristics

26.1313GPPRelease 17RequirementsTerminal acoustic characteristics for telephonyTS

Echo cancellation is commonly deployed in the UE to fulfil the Acoustic echo control requirements. Echo cancellers are complex devices of which the subjective performance is affected by several attributes. The main attribute is its ability to suppress echo. The process of suppressing the echo may introduce impairments to the near-end speech signal, mainly manifested as distortion or clipping of the near-end signal during simultaneous speech from both the far and near-end ("double-talk").

To characterise the echo control performance, the activity (in % of total time) and averaged level difference (in dB) of the duration of any level difference according to Figure 6a and Table 8a between the clean near-end signal and the send-signal shall be reported for "double-talk" as well as the far-end single talk periods adjacent to the "double-talk".

NOTE: The limits for specifying the categories in Figure 6a and Table 8a are provisional pending further analysis and validation.

NOTE: The categories in Figure 6a and Table 8a are labelled in a functional order and the subjective impression of the respective categories is for further study.

All percentage values and averaged level differences described in the relevant test of 3GPP TS 26.132 shall be reported.

Figure 6a: Classification of echo canceller performance

Table 8a: Categories for echo canceller performance classification

Category

Description

A1

Full-duplex and full transparency

A2

Full-duplex with level loss in Tx

B

Very short clipping

C

Short clipping resulting in loss of syllables

D

Clipping resulting in loss of words

E

Very short residual echo

F

Echo bursts

G

Continuous echo

5.13.1 Handset

Requirements are for further study.

5.13.2 Headset

Requirements are for further study.

5.13.3 Handheld hands-free

Requirements are for further study.

5.13.4 Desktop and vehicle mounted hands-free

Requirements are for further study.

5.13.5 Electrical interface

Requirements are for further study.