15a Support of non-transparent bearer services in Iu mode

3GPP48.020Rate adaption on the Base Station System - Mobile-services Switching Centre (BSS - MSC) interfaceRelease 17TS

In Iu mode the RLP frames are transmitted via the Iu interface by means of the Iu UP protocol in support mode, see 3GPP TS 25.415. Each SDU is transported in one Iu UP PDU type 1.

Each SDU has a size of 576 bits and carries one RLP frame with frame size of 576 bits if TCH/F14.4, TCH/F28.8 or TCH/F43.2 channel coding is used in GERAN. Each SDU has a size of 480 bits and carries two RLP frames with frame size of 240 bits if TCH/F9.6 channel coding is used in GERAN.

If TCH/F14.4, TCH/28.8 or TCH/F43.2 is used, the range of AIUR values is 14,4 kbit/s, 28,8 kbit/s, 43,2 kbit/s, 57,6 kbit/s, limited by the maximum bit rate, and varies with the transmission period on the Um interface, which is 40 ms, 20 ms, 13⅓ ms or 10 ms. If TCH/F9.6 is used, the range of AIUR values is 12, 24, 36, 48 kbit/s, limited by the maximum bit rate, and varies with the transmission on the Um interface, which is 40 ms, 20 ms, 13⅓ ms or 10 ms. A change in the transmission period is signalled to the IWF through the Iu UP protocol. The Iu UP primitive Iu-UP‑DATA-REQUEST is invoked each time an RLP frame is ready to be sent from the IWF towards the UE.

DTX indication is not used.