5G Architecture Co-existence with Non-3GPP System

Multi-access capabilities are improved in Rel-16, as it will natively support fixed access as well as providing simultaneous multi-access capabilities to maximize data rates, increase reliability and improve user experience. This release specifies a 5G Access Gateway Function that adapts fixed access onto the 5G Core and extends the 5GC control plane to the home network, and a 5G Residential Gateway that leverages that control plane to enable new services. User equipment (UE) in the 5G era comprised of two types: 5G RG and NG UE.5G Residential Gateway is an upgraded version of the traditional RG and is connected as a UE to the 5G core network through a fixed or mobile network. 5G RG can be connected to the core network via FWA or hybrid links. Next Generation UE is an upgraded version of the original UE and is connected to the 5G core network through WLAN or cellular networks. NG UE can be connected via Wi-Fi or cellular networks to offload some traffic, or via both WLAN and cellular networks. In both cases, Residential Gateway serves as a trusted node to provide Wi-Fi access. The connectivity options include 5G-RG (RG enhanced with 5G capabilities) connecting via wireline access, 5G-RG using 3GPP access (Hybrid access) and legacy RG (FN-RG) using wireline access.

5GC+5G-RG with Wireline 5G access network and NGRAN

5G-RG can be connected to 5GC via W-5GAN, NG RAN or via both accesses. 5G RG provides the connection between the network equipment within a home or small office to the 5G core network and then on to a DN such as the Internet. 5G RG could support both a wireless interface (Uu), similar to a FWA deployment and the wireline interface (Y4) towards the 5G core via the W-AGF (Wireline – Access Gateway Function). It is this which supports the standard 3GPP reference points N2 and N3 towards the AMF (Access and Mobility management Function) and UPF (User Plane Function) respectively in much the same way as a 5G base station or gNB. However, the 5G RG also supports the 3GPP N1 reference point which is used to pass NAS (Non-Access Stratum) signaling between it and the AMF. Therefore, before any data can be transferred across the wireline network, the 5G RG must first register with the AMF and trigger the establishment of a PDU Session. This may contain a number of QoS Flows to support the broad range of services that may wish to utilize this connection – IPTV, Voice, Internet and IoT etc. Furthermore, Network Slicing can also be supported across the wireline network. Thus, in the case of streaming video, the data will flow from the video server connected to the Data Network via the N6 reference point to the UPF. From here, it will be tunneled to the W-AGF via the N3 reference point using the protocol GTP (GPRS Tunneling Protocol) and finally across the wireline connection (Y4) to the 5G RG which in turn may transfer the information to any Media device using ethernet or Wi-Fi within the home network.

5GC+Fixed Network Residential Gateway with Wireline 5G access network and NGRAN

In addition to the 5G RG, another endpoint is also defined as FN RG (Fixed Network Residential Gateway). This operates in a similar way to the 5G RG however it does not support the 3GPP N1 reference point. As such, the W-AGF would need to deal with the NAS signaling on its behalf. N1 for the FN-RG, which is not 5G capable, is terminated on W-AGF which acts on behalf of the FN-RG. It can only be connected to 5GC via W-5GAN. The reference architecture only shows the architecture and the network functions directly connected to Wireline 5G Access Network, and other parts of the architecture are the same. Reference architecture supports service-based interfaces for AMF, SMF and other NFs not represented in the figure. The two N2 instances apply to a single AMF for a 5G-RG which is simultaneously connected to the same 5G Core Network over 3GPP access and Wireline 5G Access Network. The two N3 instances may apply to different UPFs when different PDU Sessions are established over 3GPP access and Wireline 5G Access Network

2 Likes