3 General approach

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

3GPP TS 43.010 (clause 6) defines the PLMN connection types necessary to support the data and telematic services in a PLMN operating in A/Gb mode or GERAN Iu mode.

Within the BSS , transcoder and IWF, there are several data rate adaptation functions which are combined as shown in 3GPP TS 43.010 as part of a connection type.

These functions are RA0, RA1, RA1/RA1′ , RA1” , RA1’/RA1", RA1’/RAA", RA1′, RAA", RA1’/RAA’, RAA’ , RAE and RA2. The RA2 function is equivalent to that described in ITU-T Recommendation V.110. In addition, splitting/combining, padding and inband numbering functions as defined in 3GPP TS 44.021 and multiplexing as defined herein are used in cases where more than one channel is allowed.

The RA1/RA1′, RA1’/RA1", RA1’/RAA" and RA1’/RAA’ are relay functions used as indicated in 3GPP TS 43.010.

The BSS uses the information contained in the ASSIGNMENT REQUEST message on the A-interface (see 3GPP TS 48.008) to set the "E bits" and to map the "D bits" as shown below, as well as to choose the correct channel coding.