5a The RA1′ Function
3GPP48.020Rate adaption on the Base Station System - Mobile-services Switching Centre (BSS - MSC) interfaceRelease 17TS
The RA1′ function is used to adapt between the synchronous data rates and the radio interface rates, i.e. it maps the data provided in the Iu UP SDUs into modified V.110 60 bit frame structure. It is specified in 3GPP TS 44.021.
In the BSS, the RA1′ function is only applicable in GERAN Iu mode if TCH/F9.6 channel coding is used.