F.1 General

26.1323GPPRelease 18Speech and video telephony terminal acoustic test specificationTS

This Annex provides packet delay and loss profiles to be inserted on the IP packets in the test system when testing the UE delay and speech quality for speech-only with LTE or WLAN access in jitter and error conditions, to characterise the jitter buffer management behaviour. The profiles are based on the assumption that one IP packet corresponds to 20ms of the speech sequence. In order to preserve the synchronization of the elements in the profile and the timing of the speech sequence (e.g. the RTP time stamp) when the speech codec does not produce one packet every 20ms, e.g. during speech codec DTX operation, the profiles needs to be sub-sampled in accordance with the rate of production of the packets containg the speech frames.