11.2 Protocol Model (Informative)

25.4013GPPRelease 17TSUTRAN overall description

The following subclause is a informative subclause which aim is to provide an overall picture of how the MAC layer is distributed over Uu, Iub and Iur for the RACH, FACH, DCH, [TDD – DSCH, USCH] and HS-DSCH.

11.2.1 RACH Transport Channel

Figure 11 shows the protocol stack model for the RACH transport channel when the Controlling and Serving RNC are co-incident.

For the RACH transport channel, Dedicated MAC (MAC-d) uses the services of Common MAC (MAC-c/sh).

Figure 11: RACH: Coincident Controlling and Serving RNC

The Common MAC (MAC-c/sh) entity in the UE transfers MAC-c/sh PDU to the peer MAC-c/sh entity in the RNC using the services of the Physical Layer.

An Interworking Function (IWF) in the Node B interworks the RACH frame received by the PHY entity into the RACH Frame Protocol (RACH FP) entity.

The RACH Frame Protocol entity adds header information to form a RACH FP PDU that is transported to the RNC over a transport bearer.

At the RNC, the RACH FP entity delivers the MAC-c/sh PDU to the MAC-c/sh entity.

Figure 12 shows the protocol model for the RACH transport channel with separate Controlling and Serving RNC. In this case, Iur RACH Frame Protocol (RACH FP) is used to interwork the Common MAC (MAC-c/sh) at the Controlling RNC with the Dedicated MAC (MAC-d) at the Serving RNC.

Figure 12: RACH: Separate Controlling and Serving RNC

11.2.2 CPCH [FDD] Transport Channel

Void.

11.2.3 FACH Transport Channel

Figure 15 shows the protocol model for the FACH transport channel when the Controlling and Serving RNC are co-incident.

Figure 15: FACH Co-incident Controlling and Serving RNC

The Common MAC (MAC-c/sh/m) entity in the RNC transfers MAC-c PDU to the peer MAC-c entity in the UE using the services of the FACH Frame Protocol (FACH FP) entity.

The FACH Frame Protocol entity adds header information to form a FACH FP PDU which is transported to the Node B over a transport bearer.

An Interworking Function (IWF) in the Node B interworks the FACH frame received by FACH Frame Protocol (FACH FP) entity into the PHY entity.

FACH scheduling is performed by MAC-c/sh/m in the CRNC.

Figure 16 shows the protocol model for the FACH transport channel with separate Controlling and Serving RNC. In this case, Iur FACH Frame Protocol is used to interwork the Common MAC (MAC-c) at the Controlling RNC with the Dedicated MAC (MAC-d) at the Serving RNC.

Figure 16: FACH: Separate Controlling and Serving RNC

11.2.4 DCH Transport Channel

Figure 17 shows the protocol model for the DCH transport channel when the Controlling and Serving RNC are co-incident.

Figure 17: DCH: Co-incident Controlling and Serving RNC

The DCH transport channel introduces the concept of distributed PHY layer.

An Interworking Function (IWF) in the Node B interworks between the DCH Frame Protocol (DCH FP) entity and the PHY entity.

Figure 18: DCH: Separate Controlling and Serving RNC

Figure 18 shows the protocol model for the DCH transport channel with separate Controlling and Serving RNC. In this case, the Iub DCH FP is terminated in the CRNC and interworked with the Iur DCH FP through a PHY function. This function performs optional soft handover or can be a null function.

11.2.5 DSCH Transport Channel [TDD]

Figure 19 shows the protocol model for the DSCH transport channel when the Controlling and Serving RNC are co-incident.

Figure 19: DSCH Co-incident Controlling and Serving RNC

The Shared MAC (MAC-c/sh) entity in the RNC transfers MAC-c/sh PDU to the peer MAC-c/sh entity in the UE using the services of the DSCH Frame Protocol (DSCH FP) entity. The DSCH FP entity adds header information to form a DSCH FP PDU that is transported to the Node B over a transport bearer.

An Interworking Function (IWF) in the Node B interworks the DSCH frame received by DSCH FP entity into the PHY entity. DSCH scheduling is performed by MAC-c/sh in the CRNC.

Figure 20 shows the protocol model for the DSCH transport channel with separate Controlling and Serving RNC. In this case, Iur DSCH Frame Protocol is used to interwork the MAC-c/sh at the Controlling RNC with the MAC-d at the Serving RNC.

Figure 20: DSCH: Separate Controlling and Serving RNC

11.2.6 USCH Transport Channel [TDD]

Figure 21 shows the protocol model for the USCH transport channel when the Controlling and Serving RNC are co-incident.

Figure 21: USCH Co-incident Controlling and Serving RNC

The Shared MAC (MAC-c/sh) entity in the RNC receives MAC-c/sh PDU from the peer MAC-c/sh entity in the UE using the services of the Interworking Function in the Node B, and the USCH Frame Protocol (USCH FP) entity. The USCH FP entity in the Node B adds header information to form a USCH FP PDU that is transported to the RNC over a transport bearer.

An Interworking Function (IWF) in the Node B interworks the received USCH PHY entity into an USCH frame to be transmitted by the USCH FP entity over the Iub interface. USCH scheduling is performed by MAC-c/sh in UE and by C-RRC in the CRNC.

Figure 22 shows the protocol model for the USCH transport channel with separate Controlling and Serving RNC. In this case, Iur USCH Frame Protocol is used to interwork the MAC-c/sh at the Controlling RNC with the MAC-d at the Serving RNC.

Figure 22: USCH: Separate Controlling and Serving RNC

11.2.7 HS-DSCH Transport Channel

Figure 23 shows the protocol model for the HS-DSCH transport channel when the Controlling and Serving RNC are co-incident. [FDD and 1.28 Mcps TDD – The protocol model in Figure 23 is applied for HS-DSCH configured for UEs in Cell_DCH.]

Figure 23: HS-DSCH Co-incident Controlling and Serving RNC

The High Speed MAC (MAC-hs) or Enhanced High Speed MAC (MAC-ehs) entity in the Node B transfers MAC-hs (or MAC-ehs) PDU to the peer MAC-hs (or MAC-ehs) entity in the UE over the Uu interface. The Dedicated MAC (MAC-d) entity in the RNC transfers MAC-d PDUs to the MAC-hs or MAC-ehs in the Node B using the services of the HS-DSCH Frame Protocol (HS-DSCH FP) entity. The HS-DSCH FP entity adds header information to form a HS-DSCH FP PDU that is transported to the Node B over a transport bearer.

A Relaying Function in the Node B relays the HS-DSCH frame received by HS-DSCH FP entity to the MAC-hs (or MAC-ehs) entity. HS-DSCH scheduling is performed by MAC-hs (or MAC-ehs) in the Node B.

Figure 24 shows the protocol model for the HS-DSCH transport channel with separate Controlling and Serving RNC. [FDD and 1.28 Mcps TDD – The protocol model in Figure 24 is applied for HS-DSCH configured for UEs in Cell_DCH.] In this case, Iur HS-DSCH Frame Protocol is used to interwork the Flow Control function at the Controlling RNC with the MAC-d at the Serving RNC. Also in this case, Iub HS-DSCH Frame Protocol is used to interwork the MAC-hs (or MAC-ehs) at the Node B with the Flow Control function at the Controlling RNC.

Figure 24: HS-DSCH: Separate Controlling and Serving RNC (configuration with CRNC flow control)

Figure 25 shows the protocol model for the HS-DSCH transport channel with the Controlling RNC user plane RNL being bypassed. [FDD and 1.28 Mcps TDD – The protocol model in Figure 25 is applied for HS-DSCH configured for UEs in Cell_DCH.] In this case, the CRNC does not have any user plane RNL function for the HS-DSCH. MAC-d in SRNC is located directly above MAC-hs (or MC-ehs) in Node B, i.e. in the HS-DSCH user plane RNL, the SRNC is directly connected to the Node B, thus bypassing the CRNC user plane RNL. The CRNC performs only user plane TNL functions.

Figure 25: HS-DSCH: Serving RNC with bypassed Controlling RNC (configuration without CRNC flow control)

[FDD and 1.28 Mcps TDD – Figure 25A shows the protocol model for the HS-DSCH transport channel configured for UE in Cell_FACH, Cell_PCH and URA_PCH, when the Controlling and Serving RNC are co-incident.

The Common MAC (MAC-c/sh/m) entity in the RNC transfers MAC-c PDU to the peer MAC-c entity in the UE using the services of the HS-DSCH Frame Protocol (HS-DSCH FP) entity.

The HS-DSCH Frame Protocol entity adds header information to form a HS-DSCH FP PDU which is transported to the Node B over a transport bearer.

The Enhanced High Speed MAC (MAC-ehs) entity in the Node B transfers MAC-ehs PDU to the peer MAC-ehs entity in the UE over the Uu interface. ]

Figure 25A: HS-DSCH configured for UE in Cell_FACH, Cell_PCH and URA_PCH: Co-incident Controlling and Serving RNC (FDD and 1.28 Mcps TDD only)

[FDD and 1.28 Mcps TDD – Figure 25B shows the protocol model for the HS-DSCH transport channel configured for UE in Cell_FACH, Cell_PCH and URA_PCH, with separate Controlling and Serving RNC. In this case, Iur HS-DSCH Frame Protocol is used to interwork the Flow Control function at the MAC-c at Controlling RNC with the MAC-d at the Serving RNC. Also in this case, Iub HS-DSCH Frame Protocol is used to interwork the MAC-ehs at the Node B with the Flow Control function at the MAC-c at the Controlling RNC.]

Figure 25B: HS-DSCH configured for UE in Cell_FACH, Cell_PCH and URA_PCH: Serving RNC with Separate Controlling and Serving RNC (FDD and 1.28 Mcps TDD only)

11.2.8 E-DCH Transport Channel

Figure 26 shows the protocol model for the E-DCH transport channel when the Controlling and Serving RNC are co-incident. [FDD and 1.28 Mcps TDD – The protocol model in Figure 26 is applied for E-DCH configured for UEs in Cell_DCH.]

Figure 26: E-DCH Co-incident Controlling and Serving RNC

The E-DCH MAC (MAC-e/MAC-es)/Enhanced E-DCH MAC (MAC-i/MAC-is) entity in the UE transfers MAC-e /MAC-i PDUs to the peer MAC-e/MAC-i entity in the Node B and MAC-es/MAC-is PDUs to the peer MAC-es /MAC-is entity in the RNC using the services of the Physical Layer.

The E-DCH FP entity adds header information to form a E-DCH FP PDU that is transported to the RNC over a transport bearer.

An Interworking Function (IWF) in the Node B interworks the E-DCH frame received by the MAC-e/MAC-i entity into the E-DCH Frame Protocol (E-DCH FP) entity. E-DCH scheduling is performed by MAC-e/MAC-i in the Node B and reordering is performed by MAC-es/MAC-is in the RNC.

Figure 27 shows the protocol model for the E-DCH transport channel with separate Controlling and Serving RNC. [FDD and 1.28 Mcps TDD – The protocol model in Figure 27 is applied for E-DCH configured for UEs in Cell_DCH.] In this case, the CRNC does not have any user plane RNL function for the E-DCH. MAC-es/MAC-is in SRNC is located directly above MAC-e/MAC-is in Node B, i.e. in the E-DCH user plane RNL, the SRNC is directly connected to the Node B, thus bypassing the CRNC user plane RNL. The CRNC performs only user plane TNL functions.

Figure 27: E-DCH: Separate Controlling and Serving RNC

[FDD and 1.28 Mcps TDD – Figure 28 shows the protocol model for the E-DCH transport channel configured for UE in Cell_FACH for CCCH transmission.

The E-DCH MAC (MAC-i/MAC-is) entity in the UE transfers MAC-i and MAC-is PDUs to the peer MAC-i in the Node B and and MAC-is entity in the CRNC.

The E-DCH FP entity adds header information to form a E-DCH FP PDU that is transported to the RNC over a transport bearer.]

Figure 28: E-DCH configured for UE in Cell_FACH(CCCH case)(FDD and 1.28 Mcps TDD only)

[FDD and 1.28 Mcps TDD – Figure 29 shows the protocol model for the E-DCH transport channel configured for UE in Cell_FACH for DCCH and DTCH transmission when the Controlling and Serving RNC are co-incident.

The E-DCH MAC (MAC-i/MAC-is) entity in the UE transfers MAC-i PDUs to the peer MAC-i entity in the Node B and MAC-is PDUs to the peer MAC-is entity in the RNC using the services of the Physical Layer.

The E-DCH FP entity adds header information to form anE-DCH FP PDU that is transported to the RNC over a transport bearer.

An Interworking Function (IWF) in the Node B interworks the E-DCH frame received by the MAC-i entity into the E-DCH Frame Protocol (E-DCH FP) entity. E-DCH scheduling is performed by MAC-i in the Node B and reordering is performed by MAC-is in the RNC.]

Figure 29: E-DCH configured for UE in Cell_FACH (DCCH/DTCH case) :Co-incident Controlling and Serving RNC (FDD and 1.28 Mcps TDD only)

[FDD and 1.28 Mcps TDD – Figure 30 shows the protocol model for the E-DCH transport channel configured for UE in Cell_FACH for DCCH and DTCH transmission, with separate Controlling and Serving RNC.

An Interworking Function (IWF) in the CRNC interworks the E-DCH data frame received from Node B into the Iur E-DCH Frame Protocol (E-DCH FP) entity.]

Figure 30: E-DCH configured for UE in Cell_FACH (DCCH/DTCH case): Separate Controlling and Serving RNC (FDD and 1.28 Mcps TDD only)