How can 4G and 5G coexist in the 5G era? - Huawei's networking mode switching method

A few days ago, Huawei launched its new phone, the Mate xs. This phone is not only a foldable phone, but also a 5G phone. However, the advent of the 5G era has also brought about many problems. The point-by-point deployment of 5G base stations requires smartphones to be compatible with both 4G and 5G modes.

The current network networking modes include independent networking (SA) and non-independent networking (NSA). Among them, the SA mode is a single network of a network standard. The NSA mode is a mixed network of multiple network standards. For example, in the fifth-generation mobile communication network (5G), the SA mode includes a single 5G network, and the NSA mode includes a mixed network of the fourth-generation mobile communication network (4G) and the 5G network.

Our mobile phones register with different networks in different networking modes, and the networks for service transmission are also different. For example, in a 5G network, when the mobile phone is in NSA mode, the terminal cannot register with the 5G access technology (NR) network, so it cannot use the 5G network. The mobile phone needs to use the dual connection (DC) solution to use the high-speed function of NR, which will generate higher power consumption.

If the terminal is in SA mode but there is no NR network in the area, the terminal will periodically search for the NR network, resulting in higher power consumption and affecting services of other standards. It will also cause problems such as slow access speed and increased terminal power consumption, affecting the user's network experience.

In order to solve this problem, Huawei applied for an invention patent entitled "A networking mode switching method, device and system" (application number: 201910579124.2) on June 28, 2019, and the applicant was Huawei Technologies Co., Ltd.

Based on the currently disclosed patent information, let us take a look at this networking mode switching method.

The above figure is a system architecture diagram of the communication system. The main core of the architecture is the terminal 101, multiple base stations 102 and the core network 103. There can be multiple base stations in the area where the terminal is located to provide users with efficient network services, and the terminal can communicate with the nearest base station according to its location to ensure smooth network operation.

The patent divides the networking mode into the first networking mode and the second networking mode. Different networking modes can be determined according to specific network requirements, and the mobile terminal can automatically or manually select the networking mode supported by the target network. The two network standards corresponding to the two networking modes are LTE and NR. Therefore, in the above system, the terminal can determine the required networking mode according to the network standard of the accessed base station.

In addition, the core network 103 in the communication system sends some key system messages to the base station 102. After receiving the system messages, the base station can forward the system messages to the terminal.

The current base station is a device that can be used with a terminal to transmit or receive signals. For example, it can be an evolved base station in Long Term Evolution (LTE), a relay station or other access point. Since future base stations can be implemented using the cloud radio access network (C-RAN) architecture, future base stations may split the protocol stack architecture and functions of traditional base stations into two parts, one called a centralized unit (CU) and the other called a distributed unit (DU), as shown in the figure below.

As shown in the figure, the CU parts of multiple base stations are integrated together to form a larger functional entity. Multiple DUs can be centrally controlled by one CU. For example, CU and DU can be divided according to the protocol layer of the wireless network. For example, the functions of the packet data convergence layer protocol layer (PDCP) and the above protocol layers (such as radio resource control) are set in the CU. The functions of the protocol layers below PDCP, such as the radio link control (RLC), the media access control layer (MAC) and the physical layer (PHY), are set in the DU.

Next, let’s take a look at the specific process of the patented networking mode switching method.

As shown in the figure above, first the base station sends a system message to the terminal, which is used to determine the networking mode supported by the target network, which is the network that the base station accesses. As before, the network standard of the base station includes any one of the first network standard and the second network standard, the first network standard is LTE, and the second network standard is NR.

When the terminal is stationed in the area where it is located, it will give priority to accessing the base station of the pre-set network standard. For example, if the area where the terminal is located includes both LTE and NR base stations, if the terminal is set to give priority to accessing the LTE base station. The terminal determines the base station list in the area (the base station list includes both LTE base stations and NR base stations), and the terminal preferentially resides in the LTE base station. After the terminal completes the residency in the corresponding base station, the base station can send a system message to the terminal.

The terminal then receives a system message from the base station. Based on the content of the message, the terminal can determine the networking mode supported by the target network where the terminal is located, and switch based on the networking mode to meet specific network requirements.

The above figure shows the interface of the network search results displayed in the actual terminal. After searching the network, the terminal determines that there are three PLMN networks in the area, namely PLMN1, PLMN2 and PLMN3. Among them, the network standard of the base station in PLMN1 includes LTE, the network standard of the base station in PLMN2 includes LTE and NR, and the network standard of the base station in PLMN3 includes NR.

The terminal displays the network list of the three PLMNs. The terminal determines to select the corresponding PLMN for the terminal according to the received PLMN list selection instruction.

It can be seen that when the flexible and automatic network is switched, the terminal communicates with different base stations at the location to complete the network mode switching of the terminal, thereby avoiding the difficulty of the terminal being unable to access the network corresponding to the area, and at the same time improving the network speed. The above is Huawei's patent for the network mode switching method. In the early days of 5G, the intersection of 4G and 5G networks is inevitable, and this patented method can flexibly allocate the two!