Considering the permutation and combination of different wireless access and core network, and considering the control surface to choose different wireless access technologies in the case of dual connection, there are a total of 8 options.
From the point of view of terminal, dual connection refers to the terminal connecting two base stations for data transmission at the same time. The scenario includes LTE and LTE, LTE and NR (New Radio New Radio), NR and NR, eLTE and eLTE, eLTE and NR. Single connection means that the terminal is connected to only one base station for data transmission. Scenarios include LTE, eLTE and NR. Based on the concepts of single and double connections, we distinguish between NSA and SA. The NSA is a non-independent network, and the terminal requires a double connection, including options 3, Option 4, Option 7 and Option 8. SA is a stand-alone network, and the terminal only needs a single connection, including options 1, Option 2, Option 5 and Option 6.
(1) Option 1: 5G terminal is connected with 4G, which cannot reflect the advantages of 5G.
(2)Option 2: Independent 5G architecture, 5G base station is connected to 5G core network.
(3) Option 3: 5G terminals are dual-connected to 5G base stations and 4G base stations, and the core network is the 4G core network. The control surface anchor point is in 4G base stations, and the user side shunt can be in 4G base stations, 5G base station, or 4G core network.
(4) Option 4:5g terminal is dual-connected to 5G base station and 4G base station, and the core network is 5G core networks. The control surface anchor point is in 5G base stations, and the user surface shunt can be in 5G base station or 5G core network.
(5) Option 5:5G terminal is only connected to 4G base station and 5G core network. Without 5G base stations, 5G advantages cannot be reflected.
(6) Option 6:5g terminal is connected to 5G base stations, 4G core network, only eMBB is supported, and 5G capacity is limited. This option requires 5G continuous coverage and is not suitable for 5G initial deployment, which has been ruled out.
(7) Option 7:5g terminal is dual-connected to 5G base station and 4G base station, and the core network is 5G core networks. The control surface anchor point is in 4G base stations, and the user side shunt can be in 4G base station, 5G base station, or 5G core network.
(8)Option 8:5g terminal is dual-connected to 5G base station and 4G base station, and the core network is 4G core networks. The control surface anchor point is in 5G base stations, and the user side shunt can be in 5G base station or 4G core network. This option requires 5G continuous coverage and 5G base stations need to connect 4G core networks and 5G core networks at the same time, increasing unnecessary responsibility, which has been excluded.
Through the analysis of 8 options, it can be seen that Option 3 is the best Option in NSA networking and Option 2 is the best Option in SA networking. The N.S.A. program would simply upgrade the 4G core network, allowing carriers to quickly roll out 5G services. But the NSA can only support high-bandwidth services, not mass connections, high-reliability, low-latency services and network slicing. SA scheme needs to build 5G core networks, which is the 5G target architecture. However, THE STANDARDS related to SA are not perfect and commercial use is difficult. Therefore, the mainstream operators in the early stage of 5G choose NSA for commercial use, and at the same time increase their efforts to test and verify SA and evolve into the target architecture SA.
