This involves a technology called DC (Dual link technology). From the 5G technology of the live network, the principle of LTE\/NR dual connection is basically the same as that of R12 LTE\/LTE dual connection, either LTE base station (eNB) is the main node, 5G base station (gNB) is the auxiliary node; Either 5G base station (gNB) is the primary node and LTE base station (eNB) is the secondary node.
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This leads to the networking mode used by the base station you occupy, that is, the option you use is the option.
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At present, most operators use option.3x. Under this option, the control plane is anchored to 4G, and all kinds of control signaling such as access, connection and handover are processed at the 4G base station. However, when the 5G base station on the user side connects to the 4G core network, the diversion and aggregation of user data traffic is also completed at the 5G base station, or it is directly transmitted to the terminal. Or part of the data is forwarded to the 4G base station and then transmitted to the terminal through the X2 interface.
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To put it bluntly, depending on the option mode you occupy, 4G and 5G data traffic is shunted at the 4G base station and then transmitted to the mobile phone terminal.
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How the 5G phone determines whether to display 4G or 5G in the case of dual links is determined by the \"upperLayerIndication\" defined by the standards organization in the LTE broadcast System Information (SIB2), which acts as a \"5G status indicator\". When set to True (on), the UE will display the 5G icon, which will let 5G users know that 5G service is available in their location when they are idle.
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Under the NSA networking architecture, 4G base stations (cell) and 5G base stations (cell) are not completely overlapping due to the different working frequency bands and antenna hanging heights, and when the mobile phone is in a different signal coverage range, the GSMA defines the following four options:
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It can be seen that Config D is the most radical. Under Config D configuration, as long as the mobile phone occupies the 4G LTE cell under the NSA network, the 5G icon will be displayed even if no 5G NR signal coverage is detected at this time. Config D is easy for users to mistake for \"fake 5G\". Config C is second, only when the phone detects 5G NR coverage will the 5G icon be displayed. B and A are also analyzed in this way.
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Global operators do not agree on a single option configuration, so in practice, according to different operators and devices will be flexible according to their own preferences.
When a 5G mobile phone is used and within the coverage range of 5G signal, the status bar of the mobile phone will display 5G signal even if the mobile phone card does not open 5G plan. At this time, the phone can enjoy up to 300Mbps in a good signal (compared to the speed limit of 5G plans).
1. The display of 5G on a mobile phone without 5G package indicates that the mobile phone supports 5G network and is within the coverage range of 5G network.
2. In the case that 5G is displayed on the mobile phone without 5G plan, even if the mobile phone card is 4G plan, it can enjoy 300Mbps network speed (depending on the actual signal situation).
3. If you want to experience faster 5G network speeds, you need to open a 5G plan. With the 5G plan, the Internet speed can reach 500Mbps
You do not need to change your mobile phone card to use 5G network. The original 4G mobile phone card can use 5G network, but if you do not have 5G network coverage in your local area, you can only use 4G network for the time being.