5 The RA1 Function

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

This function shall be used to adapt between the synchronous user rates, or the output of the RA0 function or Split/Combine function and the intermediate rate of 8, 16, 32 or 64 kbit/s.

For multislot operations RA1 applies per substream. RA1 applies only if TCH/F4.8 or TCH/F9.6 is used for user rates up to 38,4 kbit/s. The RA1 function is only applicable for A/Gb mode.

Synchronous user rate

Intermediate rate

 2,4 kbit/s

8 kbit/s

4,8 kbit/s

8 kbit/s

9,6 kbit/s

16 kbit/s

14,4 kbit/s

32 kbit/s

19,2 kbit/s

32 kbit/s

28,8 kbit/s

64 kbit/s

38,4 kbit/s

64 kbit/s

An ITU-T V.110 80 bits frame is constructed using the user data bits received (from the RA0 in the asynchronous case).

Adaptation of 600 bit/s to 8Kbit/s is performed by 8 times consecutive duplication of each user data bit. (Figure 11)

Adaptation of 1200 bit/s to 8 Kbit/s is performed by 4 times consecutive duplication of each user data bit. (Figure 10)

Adaptation of 2400 bit/s to 8kbit/s is performed by 2 times consecutive duplication of each user data bit. (Figure 9)

Adaptation of 4800 bit/s to 8 Kbit/s is performed by transmitting the bit stream with no duplication. (Figure 7)

Adaptation of 9600 bit/s to 16 Kbit/s is performed by transmitting the bit stream with no duplication (the emitting period is halved with respect to the 4800 bit/s case). (Figure 7)

Adaptation of 14400 bit/s to 32 Kbit/s is performed as for 3600 bit/s to 8 kbit/s (the emitting period is divided by four with respect to the 3600 bit/s case).( Adaptation of 3600 bit/s to 8 kbit/s is performed by transmitting the bit stream with no duplication.) (Figure 8)

Adaptation of 19200 bit/s to 32 Kbit/s is performed as for 4800 bit/s to 8 kbit/s (the emitting period is divided by four with respect to the 4800 bit/s case). (Figure 7)

Adaptation of 28800 bit/s to 64 Kbit/s is performed as for 3600 bit/s to 8 kbit/s (the emitting period is divided by eight with respect to the 3600 bit/s case). (Figure 8)

Adaptation of 38400 bit/s to 64 Kbit/s is performed as for 4800 bit/s 8 kbit/s (the emitting period is divided by eight with respect to the 4800 bit/s case). (Figure 7)

The ITU-T V.110 80 bit frames shown in Figures 7 and 8 are used. The meaning of the bits is specified in 3GPP TS 44.021.