6 Control and User Plane Architecture

3GPP43.318Generic Access Network (GAN)Release 17Stage 2TS

6.1 CS Domain (GAN A/Gb mode)

6.1.1 CS Domain – Control Plane

6.1.1.1 CS Domain – Control Plane – GAN Architecture

The GAN architecture in support of CS Domain control plane is illustrated in figure 2.

Figure 2: Up CS Domain Control Plane Architecture

The main features of the Up interface for the CS domain control plane are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity.

– TCP provides reliable transport for the GA-RC between MS and GANC and is transported using the Remote IP layer.

– The GA-RC manages the IP connection, including the GAN registration procedures.

– The GA-CSR protocol performs functionality equivalent to the GSM-RR protocol, using the underlying connection managed by the GA-RC.

– Protocols, such as MM and above, are carried transparently between the MS and MSC.

– The GANC terminates the GA-CSR protocol and inter-works it to the A-interface using BSSAP messaging.

– The Remote IP layer is the ‘inner’ IP layer for IPsec tunnel mode and is used by the MS to be addressed by the GANC. Remote IP layer is configured during the IPsec connection establishment.

6.1.1.2 CS Domain – Control Plane – MS Architecture

The MS architecture for the CS domain control plane in the MS is illustrated in figure 3.

Figure 3: MS CS Domain Control plane Architecture

Figure 3 illustrates the main features of the MS CS Domain Control Plane architecture, which are as follows:

– The RR-SAP interface to the GSM-MM layer is preserved identically for both GSM and GAN access.

– An access mode switch is provided to switch between GERAN/UTRAN and GAN A/Gb modes.

– GA-CSR peers with GSM-RR to provide coordination for roving and handover.

6.1.2 CS Domain – User Plane

6.1.2.1 CS Domain – User Plane – GAN Architecture

The GAN protocol architecture in support of CS domain user plane is illustrated figure 4.

Figure 4: Up CS Domain User Plane Protocol Architecture

The main features of the CS domain user plane of the Up interface are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity.

– CS domain user plane is transported over RTP/UDP between MS and GANC.

– Support for AMR FR codec, as specified in 3GPP TS 26.071 [7], is mandatory when operating in GAN A/Gb mode, with support for other codecs being optional.

– CS-data is transported over RTP/UDP, by defining a new RTP frame format to carry the TAF-TRAU (V.110‑like) frames over RTP.

– TTY is transported using CTM over GSM codec over RTP/UDP.

– When using a TDM-based A-interface, the GANC re-frames and transcodes the CS domain user plane between RTP/UDP speech bearer and the speech bearers over the A-interface. Re-framing and transcoding is not required when the voice call uses AMR over an IP-based A-interface.

NOTE: RTP redundancy is not used over the Up interface when the voice call uses an IP-based A-interface.

6.2 PS Domain (GAN A/Gb mode)

6.2.1 PS Domain – GAN Architecture

6.2.1.1 PS Domain – Control Plane – GAN Architecture

The GAN architecture in support of PS Domain Control Plane is illustrated in figure 5.

Figure 5: Up PS Domain Control Plane Architecture

The main features of the Up interface for the PS domain control plane are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity.

– TCP provides reliable transport for the GA-PSR between MS and GANC.

– The GA-RC manages the IP connection, including the GAN registration procedures.

– The GA-PSR protocol performs functionality equivalent to the GPRS-RLC protocol. The concept of a TBF is replaced by mechanisms to manage an IP connection between MS and GANC.

NOTE: No QoS can be assured when utilizing the GA-PSR transport channel.

– Protocols, such as LLC and above, are carried transparently between the MS and CN.

– The GANC terminates the GA-PSR protocol and inter-works it to the Gb-interface using BSSGP.

6.2.1.2 PS Domain – User Plane – GAN Architecture

The GAN architecture for PS Domain User Plane is illustrated in figure 6.

Figure 6: Up PS Domain User Plane Protocol Architecture

The main features of the Up interface for PS domain user plane are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity.

– The GA-PSR operates between the MS to the GANC transporting the upper layer payload (i.e. user plane data)across the Up interface.

– Protocols and data, such as LLC and above, are carried transparently between the MS and CN.

– The GANC terminates the GA-PSR protocol and inter-works it to the Gb-interface using BSSGP.

6.2.2 PS Domain – MS Architecture

The MS architecture for the PS domain is illustrated in more detail in figure 7.

Figure 7: MS PS Domain Architecture

Figure 7 illustrates the main features of the MS PS Domain architecture, which are as follows:

– The GRR-SAP to the GPRS-LLC layer is preserved.

– The GMMRR-SAP interface to the GPRS-GMM layer is preserved.

– An access mode switch is provided to switch between GPRS and GAN A/Gb modes.

– GA-PSR peers with GPRS-RLC to provide coordination for roving and PS handover.

6.3 CS Domain (GAN Iu mode)

6.3.1 CS Domain – Control Plane

6.3.1.1 CS Domain – Control Plane – GAN Architecture

The GAN Iu mode architecture in support of the CS Domain control plane is illustrated in figure 7a.

Figure 7a: CS Domain Control Plane Architecture

The main features of the GAN Iu mode CS domain control plane architecture are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity between the MS and GANC.

– The Remote IP layer is the ‘inner’ IP layer for IPsec tunnel mode and is used by the MS to be addressed by the GANC. The Remote IP layer is configured during the IPsec connection establishment.

– A single TCP connection is used to provide reliable transport for both the GA-RC and GA-RRC signaling between the MS and GANC. The TCP connection is managed by GA-RC and is transported using the Remote IP layer.

– NAS protocols, such as MM and above, are carried transparently between the MS and MSC.

– The Generic Access Resource Control (GA-RC) protocol manages the Up session, including the GAN discovery and registration procedures.

– The Generic Access Radio Resource Control (GA-RRC) protocol performs functionality equivalent to the UTRAN RRC protocol, using the underlying Up session managed by the GA-RC. Note that GA-RRC includes both CS service and PS service-related signaling messages.

– The GANC terminates the CS-related GA-RRC protocol and inter-works it to the RANAP protocol over the Iu-cs interface.

– The Iu-cs signalling transport layer options (both ATM and IP-based) are defined in TS 25.412 [47].

6.3.1.2 CS Domain – Control Plane – MS Architecture

The MS architecture for the CS domain control plane is illustrated in figure 7b. The MS architecture illustrates support for both GAN A/Gb mode and GAN Iu mode.

Figure 7b: MS CS Domain Control Plane Architecture

Figure 7b illustrates the main features of the MS CS domain control plane architecture, which are as follows:

– The UTRAN RR-SAP interface to the MM layer is preserved identically for both UTRAN and GAN Iu mode access.

– The GERAN RR-SAP interface to the MM layer is preserved identically for both GERAN and GAN A/Gb mode access.

– An access mode switch is provided to switch between GERAN/UTRAN and GAN modes.

– GA-RRC (GAN Iu mode) peers with UTRAN-RRC and GERAN-RRC to provide coordination for roving and handover.

– GA-CSR (GAN A/Gb mode) peers with UTRAN-RRC and GERAN-RRC to provide coordination for roving and handover.

6.3.2 CS Domain – User Plane

6.3.2.1 CS Domain – User Plane – GAN Architecture

The GAN Iu mode protocol architecture in support of the CS domain user plane is illustrated figure 7c.

Figure 7c: CS Domain User Plane Protocol Architecture

The main features of the GAN CS domain user plane architecture are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity.

– CS domain user plane is transported over RTP/UDP between MS and GANC.

– Support for AMR FR codec, as specified in 3GPP TS 26.071 [7], is mandatory when operating in GAN Iu mode, with support for other codecs being optional.

– CS-data is transported over RTP/UDP, by defining a new RTP frame format to carry the TAF-TRAU (V.110‑like) frames over RTP.

– TTY is transported using CTM over GSM codec over RTP/UDP.

– The GANC provides interworking between RTP/UDP and the circuit switched bearers over the Iu-cs interface.

– The GANC supports the Iu User Plane (Iu UP) protocol. Each Iu UP protocol instance may operate in either transparent or support modes, as described in 25.415 [50]; the mode choice is indicated to the GANC by the MSC using RANAP.

– The Iu-cs data transport layers (both ATM and IP-based) and associated transport network control options are defined in 25.414 [49].

6.3.2.2 CS Domain – User Plane – MS Architecture

The MS architecture for the CS domain user plane is illustrated in figure 7d. The MS architecture illustrates support for both GAN A/Gb mode and GAN Iu mode.

Figure 7d: MS CS Domain User Plane Architecture

Figure 7d illustrates the main features of the MS CS domain user plane architecture, which are as follows:

– An access mode switch is provided to switch between GERAN/UTRAN and GAN modes; i.e., to route CS user plane data—either speech or circuit switched data—to the active access subsystem.

6.4 PS Domain (GAN Iu mode)

6.4.1 PS Domain – Control Plane

6.4.1.1 PS Domain – Control Plane – GAN Architecture

The GAN Iu mode architecture in support of the PS Domain Control Plane is illustrated in figure 7e.

Figure 7e: PS Domain Control Plane Architecture

The main features of the GAN PS domain control plane architecture are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity.

– TCP provides reliable transport for the GA-RRC between MS and GANC.

– The GA-RC manages the IP connection, including the GAN registration procedures.

– The Generic Access Radio Resource Control (GA-RRC) protocol performs functionality equivalent to the UTRAN RRC protocol, using the underlying Up session managed by the GA-RC. Note that GA-RRC includes both CS service and PS service-related signaling messages.

– The GANC terminates the GA-RRC protocol and inter-works it to the RANAP protocol over the Iu-ps interface.

– NAS protocols, such as for GMM, SM and SMS, are carried transparently between the MS and SGSN.

– The Iu-ps signalling transport layer options (both ATM and IP-based) are defined in 25.412 [47].

6.4.1.2 PS Domain – Control Plane – MS Architecture

The MS architecture for the PS domain control plane is illustrated in figure 7f. The MS architecture illustrates support for both GAN A/Gb mode and GAN Iu mode.

Figure 7f: MS PS Domain Control Plane Architecture

Figure 7f illustrates the main features of the MS PS domain control plane architecture, which are as follows:

– The UTRAN RABMAS-SAP and GMMAS-SAP interfaces to the MM layer are preserved identically for both UTRAN and GAN Iu mode access.

– The GERAN GRR-SAP and GMMRR-SAP interfaces to the MM layer are preserved identically for both GERAN and GAN A/Gb mode access.

– An access mode switch is provided to switch between GERAN/UTRAN and GAN modes.

– GA-RRC (GAN Iu mode) peers with UTRAN-RRC and GERAN-RRC to provide coordination for roving and handover.

– GA-PSR (GAN A/Gb mode) peers with UTRAN-RRC and GERAN-RRC to provide coordination for roving and handover.

6.4.2 PS Domain – User Plane

6.4.2.1 PS Domain – User Plane – GAN Architecture

The GAN Iu mode architecture for the PS Domain User Plane is illustrated in figure 7g.

Figure 7g: PS Domain User Plane Protocol Architecture

The main features of the GAN PS domain user plane architecture are as follows:

– The underlying Access Layers and Transport IP layer provides the generic connectivity between the MS and the GANC.

– The IPsec layer provides encryption and data integrity.

– The GA-RRC protocol operates between the MS to the GANC transporting the upper layer payload (i.e. user plane data) across the Up interface.

– PS user data is carried transparently between the MS and CN.

– The GANC terminates the GA-RRC protocol and inter-works it to the Iu-ps interface using GTP-U.

6.4.2.2 PS Domain – User Plane – MS Architecture

The MS architecture for the PS domain user plane is illustrated in figure 7h.

Figure 7h: MS PS Domain User Plane Architecture

Figure 7h illustrates the main features of the MS PS domain user plane architecture, which are as follows:

– The UTRAN PDCP-SAP interface to the PS user plane upper layers is preserved identically for both UTRAN and GAN Iu mode access.

– The GERAN GRR-SAP interface to the PS user plane upper layers is preserved identically for both GERAN and GAN A/Gb mode access.

– An access mode switch is provided to switch between GERAN/UTRAN and GAN modes; i.e., to route PS user plane data to the active access subsystem.