12 Sa4 Features

12.1 Requirements and Test methods for Wideband Terminals (retem_wb_t) uid_34045

Resources: S4

References

Document	Title/Contents
WID(s)
SP-080004	WID on Requirements and Test methods for Wideband Terminals
Impacted Specifications
TS 26.131	Terminal acoustic characteristics for telephony; Requirements
TS 26.132	Speech and video telephony terminal acoustic test specification
New Dedicated Specifications/Reports
-	-

Supporting Individual Members: Orange, France Telecom, T-Mobile International, Vodafone, Ericsson, Nokia.

UID	Name	Resource	Hyperlink	TS_TR
34045	Requirements and Test methods for Wideband Terminals	S4	SP-080004	26.131, 26.132

Recognizing the advantages brought by WideBand (WB) speech to the voice quality of conversational services, 3GPP has been working for long time on this. To obtain a genuine wideband speech quality, the whole communication chain has to be considered. AMR-WB codec is a high-quality WB speech compression solution for speech transmission over 3GPP radio access and core networks but this quality could be strongly altered if the terminal is not well designed from the acoustic point of view. 3GPP has already conducted work on this issue. Requirements (TS 26.131) and test methods (TS 26.132) for narrow-band and WB terminals were already specified by SA4.

Terminal performance strongly impacts the quality as really perceived by the end-user. Subjective tests have shown that terminal acoustic design impacts the end-user perceived quality as much as the codec itself. Some requirements set in current TS 26.131 do not guarantee obtaining the optimal WB quality.

Some examples of improvements:

• A handset with sensitivity/frequency response curve considered as acceptable regarding limits in TS 26.131 cannot sufficiently render real effective WB sound to the user if its response curve is in the lower part of the defined mask. As a result the difference with narrow-band rendering could be too reduced to justify WB voice services.

• Measurement of the distortion that is done only for one frequency is not sufficient for WB speech.

Without reconsidering such points especially with respect to high-quality WB voice requirements, some terminals would use WB codecs and be declared as WB, without sufficient improvement of acoustic and analogue part. For the end-user, difference with "normal" terminal would not justify transition to WB telephony. In some cases extension of frequency without correct study could even induce lower perceived quality especially with respect to narrow band voice obtained with AMR over a well acoustically designed narrow band terminal.

This work enhances TS 26.131 requirements and TS 26.132 test methods, originally narrow band terminals standards including partial update for WB terminals, to ensure adequate perceived quality for WB speech services and interoperability between terminals (for handset, headset and hands-free).