CN112996070B

CN112996070B - Data transmission method and system based on distributed non-cellular network

Info

Publication number: CN112996070B
Application number: CN202110240254.0A
Authority: CN
Inventors: 石磊; 王东明; 刘东杰
Original assignee: Network Communication and Security Zijinshan Laboratory
Current assignee: Network Communication and Security Zijinshan Laboratory
Priority date: 2021-03-04
Filing date: 2021-03-04
Publication date: 2023-03-24
Anticipated expiration: 2041-03-04
Also published as: CN112996070A

Abstract

The embodiment of the invention discloses a data transmission method and a data transmission system based on a distributed cellular-free network, which relate to the technical field of wireless communication, can realize distributed multi-CPU node deployment and simultaneously can avoid the condition that data of single UE is processed in a distributed manner by a plurality of CPU nodes. Therefore, the complexity of cooperation among the CPU nodes is reduced, and the time delay of data processing is also reduced. The invention comprises the following steps: when the UE is in an overlapping area, performing data interaction with a first CPU through the AP in the overlapping area, wherein each CPU is connected with the AP in a service range, the overlapping area is formed when the service ranges of more than 1 CPU are overlapped, and the data interaction is realized between the AP in the overlapping area and at least 2 CPUs serving the overlapping area; and after the UE moves, the mobility management unit modifies the routing information of the front-end transmission network and routes the uplink data of the UE to the second CPU. The invention is suitable for the selection and cooperation mode of the AP taking the UE as the center.

Description

Data transmission method and system based on distributed non-cellular network

Technical Field

The present invention relates to the field of wireless communication technologies, and in particular, to a data transmission method and system based on a distributed cellular-free network.

Background

The cellular-free network and the distributed ultra-large MIMO are used as key technical directions of a future 6G network, and joint scheduling of resources and joint sending and receiving of data are realized through cooperation of multiple nodes, so that on one hand, interference is effectively eliminated, and signal receiving quality is enhanced; on the other hand, the coverage is enhanced. In a cellular-less network, multiple Access Points (APs) jointly serve a UE. A plurality of access points are aggregated at a Central Processing Unit (CPU) node. Processing downlink data CPU and then distributing the processed downlink data to a plurality of APs for sending; for the uplink data, the data of a plurality of APs are gathered to the CPU, and the CPU is merged for further processing. There are two modes for the selection and cooperation of APs. The first is a network-centric mode and the second is a UE-centric mode.

However, in the UE-centric mode, ideally all APs are connected to the same CPU node. There is a one-to-many relationship between the CPU nodes and the APs. If all APs in a set of APs serving a certain UE are connected to the same CPU node, the data of the UE needs to be distributed and aggregated at the same CPU node. However, if the UE is located at the border of the coverage of multiple CPU nodes, the APs in the UE's preferred set of APs may be connected to different CPU nodes. Some steps in the physical layer processing are less easy to implement for distributed computing. For example, in the downlink process, channel coding needs to be completed in one node, and then the channel coding can be distributed to a plurality of nodes for further processing. In the uplink processing, the data of each node needs to be combined to perform channel decoding. The current distributed CPU architecture is not well able to support this.

One existing improvement is to increase the cooperation among multiple CPU nodes. For the upstream data, each CPU node receives data from the AP connected to the node and performs distributed processing. Then, the data of a plurality of CPU nodes are converged to one CPU node for merging and post-processing; for downlink data, a certain CPU node merges UE data and distributes the merged UE data to a plurality of CPU nodes. And each CPU node is distributed to the AP connected with the CPU after further processing. However, such improvements still have drawbacks, such as: the cooperation among the CPU nodes is very complex, and the improvement scheme greatly changes a network architecture, a physical layer and a protocol stack in the implementation process; the transmission distance between the CPU nodes is large, and extra delay is added, so that the distance between the CPU nodes is limited; and high requirements on transmission network bandwidth and delay among CPU nodes.

Disclosure of Invention

Embodiments of the present invention provide a data transmission method and system based on a distributed cellular-free network, which can implement distributed multi-CPU node deployment and can avoid a situation that data of a single UE is distributively processed by multiple CPU nodes. Therefore, the complexity of cooperation among the CPU nodes is reduced, and the time delay of data processing is also reduced.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

the method provided by the embodiment of the invention comprises the following steps:

when the UE is in an overlapping area, performing data interaction with a first CPU through the AP in the overlapping area, wherein each CPU is connected with the AP in a service range, the overlapping area is formed when the service ranges of more than 1 CPU are overlapped, and the data interaction is realized between the AP in the overlapping area and at least 2 CPUs serving the overlapping area; after the UE moves, the mobility management unit modifies routing information of a front-end transmission network and routes uplink data of the UE to a second CPU, wherein a part of a service range of the first CPU is overlapped with a part of a service range of the second CPU, and an AP in the overlapped service range establishes a data channel with the first CPU and the second CPU through a forwarding network.

An embodiment of the present invention further provides a system, including: at least 2 CPUs, each CPU corresponding to at least 1 AP, AP-accessed UE, a front-end transmission network and a mobility management unit; each CPU is connected with an AP in a service range, an overlapping area is formed when the service ranges of more than 1 CPU are overlapped, data interaction is realized between the AP in the overlapping area and at least 2 CPUs serving the overlapping area, and when the UE is in the overlapping area, data interaction is carried out between the AP in the overlapping area and a first CPU; the mobile management unit is used for taking the UE which moves as the target UE to be switched and starting to execute a switching process; the front-end transmission network is used for updating routing information after the UE moves, wherein the routing information points to a CPU (central processing unit) of the UE which currently establishes data interaction.

According to the data transmission method and system based on the distributed cellular-free network, provided by the embodiment of the invention, the CPU and the AP in the overlapping area are not connected in a one-to-many manner any more, but are connected in a many-to-many manner. That is, one AP may be interconnected with a plurality of CPU nodes through a forwarding network. The AP and the CPU outside the overlapping area can be directly connected or can be connected through a forwarding network. When the service CPU changes due to the movement of the UE, the service AP and the forwarding network need to configure new routing information, so that the uplink data of the UE is routed to the new service CPU. The distributed multi-CPU node deployment can be realized, and meanwhile, the condition that data of a single UE is processed by a plurality of CPU nodes in a distributed mode can be avoided. Therefore, the complexity of cooperation among the CPU nodes is reduced, and the time delay of data processing is also reduced. Compared with the prior art, the invention has the following advantages: in the interaction between the UE and the CPU and the switching process of the CPU, the cooperation between CPU nodes is not needed, no extra delay is introduced because the data transmission between the CPUs is not needed, and a high-quality transmission network between the CPUs is also not needed to be built, so that the complexity of control is greatly reduced, and the conventional network architecture, algorithm realization and processing flow can be fully multiplexed.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1a, FIG. 1b, and FIG. 1c are schematic diagrams illustrating basic principles of a conventional network architecture;

FIG. 1d is a schematic diagram of a possible improvement to the existing network architecture;

FIG. 2 is a diagram illustrating a network architecture according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a UE granularity forwarding data route according to an embodiment of the present invention;

fig. 4 is a schematic view of a scenario in which a UE1 serving CPU is a CPU1 according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a service CPU switching manner provided in an embodiment of the present invention;

fig. 6 is a flowchart illustrating a CPU switching process according to an embodiment of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In the current mode with a UE (User Equipment) as a center, there is no longer a fixed group of APs (wireless access points), and the network dynamically selects a plurality of optimal APs to provide services for the APs according to the geographical location and channel conditions of the UE, for example, in fig. 1a, the network selects three APs in an area 1 to serve the UE1 and three APs in an area 2 to serve the UE 2. And as the UE moves, the set of APs serving the UE may change dynamically. However, in the UE-centric mode, all APs are ideally connected under the same CPU node, where the CPU node in this embodiment may be a computing resource in the base station, such as a processor in a BBU (baseband processing unit) of the base station. No matter how the AP set serving a certain UE is dynamically adjusted, data of a single UE is aggregated in the same CPU node. However, in an actual network, due to the CPU node processing capability and the connection distance, a distributed networking manner is usually required, that is, a plurality of CPU nodes distributed in different regions are networked together. The CPU node and the AP are in one-to-many relationship: one CPU node serves an AP of a slice region, and one AP is connected to one CPU node. In this networking mode, if all APs in an AP set serving a certain UE are connected to the same CPU node, data of the UE is distributed and aggregated at the same CPU node. For example, in fig. 1b, the case of UE1 and UE 2.

However, if the UE is located at the intersection of the coverage areas of multiple CPU nodes, the APs in the UE's preferred AP set may be connected to different CPU nodes. For example, in fig. 1c, the set of APs serving the UE are AP1-AP4. Wherein AP1, AP2 are connected to CPU1, and AP3, AP4 are connected to CPU2. However, some steps in the physical layer processing are less easy to implement for distributed computing. For example, in the downlink process, channel coding needs to be completed in one node, and then the channel coding can be distributed to a plurality of nodes for further processing. In the uplink processing, the data of each node needs to be combined to perform channel decoding. The distributed CPU architecture does not support this well.

Among existing solutions, one solution is to increase the cooperation among multiple CPU nodes, such as shown in fig. 1 d. Wherein, for the uplink: each CPU node receives data from an AP connected to the node and performs distributed processing. And then, the data of a plurality of CPU nodes are converged to one CPU node for merging and post-processing. For the downlink: and one CPU node combines the UE data and distributes the combined UE data to a plurality of CPU nodes. And each CPU node is distributed to the AP connected with the CPU after further processing. The disadvantages are that: 1. the cooperation among the CPU nodes is very complex, and the network architecture, the physical layer and the protocol stack are greatly changed; 2. the transmission distance between CPU nodes is large, and extra delay is increased. Therefore, the distance between CPU nodes is limited; 3. the requirements on the bandwidth and the delay of the transmission network between the CPU nodes are high.

The design idea of the embodiment of the invention is to solve or alleviate the defects in the existing scheme, so as to further optimize the data transmission scheme based on the distributed cellular-free network.

The embodiment of the invention provides a data transmission method based on a distributed cellular-free network, which mainly comprises the following processes:

and S0, acquiring the position of the user terminal.

Wherein, the positioning information of the UE can be obtained in real time, such as positioning through a satellite positioning system, or positioning through a base station.

S1, when the UE is in an overlapping area, performing data interaction with a first CPU through the AP in the overlapping area, wherein each CPU is connected with the AP in a service range, the overlapping area is formed when the service ranges of more than 1 CPU are overlapped, and the data interaction is realized between the AP in the overlapping area and at least 2 CPUs serving the overlapping area.

S2, after the UE moves, the first CPU configures new routing information through a front transport network (frontaul transport network), and routes uplink data of the UE to a second CPU.

And the AP in the overlapped service range establishes a data channel with the first CPU and the second CPU through a forwarding network. Here, the UE moves, which can be understood as moving in the direction of the service range of the second CPU. Specifically, the AP in the overlapping area is connected to the CPU through the front-end transmission network. And the AP outside the overlapping area is directly connected with the CPU, or the AP outside the overlapping area is connected with the CPU through the front-end transmission network. In practical applications, a plurality of CPU nodes are usually deployed, and overlapping coverage is implemented in the edge areas of the plurality of CPU nodes. Wherein, there is no more one-to-many connection between the CPU and the AP in the overlapping area, but many-to-many connection. That is, one AP may be interconnected with a plurality of CPU nodes through a front-end transmission network. For example, in fig. 2, AP4-AP 6 may be interconnected with CPU1 or CPU2. The AP outside the overlapping area and the CPU can be directly connected or can be connected through a front-end transmission network. The forwarding protocol adopted in the front-end transmission network is eCPRI, the front-end transmission network can be based on IP or Ethernet, and a router, a switch or an extension unit is arranged in the network to realize a routing function.

In this embodiment, the data transmitted through the front-end transmission network includes: in the downlink transmission process, bit data before or after encoding, or IQ data after encoding and modulation, or frequency domain IQ data after precoding; and in the uplink transmission process, IQ data after coherent combination, log-likelihood ratio data after detection and demodulation, and the like. The type of forwarding data in practical applications can be various. For example, bit data before or after encoding in downlink, IQ data after encoding and modulation, frequency domain IQ data after precoding, and the like.

Further, in the process of performing data interaction with the first CPU through the AP in the overlapping area, the method further includes: and separating the received uplink data of all the UEs to obtain the uplink data of each UE, wherein the separation operation is performed at an AP (access point) which is accessed by each UE respectively or at an expansion unit. Namely, UE-granularity forwarding data routing can be realized between the AP and the CPU. The type of forwarding data may be various. For example, bit data before or after encoding, IQ data after encoding and modulation, frequency domain IQ data after precoding, and the like in the downlink, IQ data after coherent combining, log likelihood ratio data after detection and demodulation, and the like in the uplink, and the frequency domain IQ data of the user is taken as an example in the following. Taking fig. 3 as an example, the frequency domain IQ data of UE1 processed by AP1 is routed to CPU1, and the frequency domain IQ data of UE2 is routed to CPU2. The separation of uplink multiple UE data may be completed in the AP or in the extension unit.

Further, the method also comprises the following steps: when the UE is in the overlapping area, performing data interaction with a first CPU through at least 2 APs in the overlapping area, and after receiving uplink data sent by the UE, the at least 2 APs in the overlapping area respectively transmit the received uplink data of the UE to the first CPU. The downlink data of the UE is processed by the first CPU and then distributed to at least 1 AP for processing and transmission.

And recording the corresponding relation between the UE and the CPU with data interaction established currently in the routing information configured by the front-end transmission network. For example: for the uplink, the AP serving the UE sends/routes the received data to the serving CPU. For example, in fig. 4, the serving APs of UE1 are AP3, AP4, and AP6, and the serving CPU is CPU1. At this time, the data received by the AP3 is transmitted to the CPU1. Data received by AP4, AP6 for UE1 will be routed to CPU1. The CPU1 processes the received data in a centralized way without cooperation with other CPUs. And for the downlink, the service CPU distributes the processed data to the service AP for processing and transmission. Specifically, for one UE, only one CPU node serves it at a time. For the uplink, the AP serving the UE sends/routes the received data to the serving CPU. For example, in fig. 4, the serving APs of UE1 are AP3, AP4, and AP6, and the serving CPU is CPU1. At this time, the data received by the AP3 is transmitted to the CPU1. Data received by AP4, AP6 for UE1 will be routed to CPU1. The CPU1 processes the received data in a centralized way without cooperation with other CPUs. And for the downlink, the service CPU distributes the processed data to the service AP for processing and transmission. When the serving CPU becomes CPU2, data received by AP6 for UE1 at this time will be routed to CPU2. The CPU2 performs centralized processing of the received data. When the service CPU changes due to the UE moving, the serving AP and the front end transport network need to configure new routing information, so as to route the UE uplink data to the new service CPU. For example: the selection and switching of the UE serving CPU can be done by a separate mobility management unit. And the mobility management unit performs switching decision according to the input of the UE position, the channel quality, the CPU node load and the like. The context of the UE needs to be migrated from the source CPU node to the destination CPU node during the handover process. And a front-end transmission network or an AP needs to be configured to perform route switching. For example, as shown in fig. 5, according to the moving direction of UE1, the set of serving APs of UE1 is changed to AP5, AP6 and AP8, and the serving CPU is changed to CPU2. Data received by AP6 for UE1 at this point will be routed to CPU2. The CPU2 performs centralized processing on the received data without cooperation with other CPUs.

In practical application, the mobility management Unit is responsible for switching a network element of the CPU, and in a hardware level, the mobility management Unit may be a CU (Control Unit) portion deployed in a base station, may also be an independent server, and may also be a service deployed in a cloud.

After the UE moves, the mobility management unit takes the moving UE as a target UE to be handed over, and starts to execute a handover procedure, as shown in fig. 6, including:

the mobility management unit receives first mobility-related measurement data sent by a first CPU and second mobility-related measurement data sent by a second CPU, and detects whether a handover condition is satisfied.

When the handover condition is satisfied, the mobility management unit transmits a handover preparation notification to the first CPU and the second CPU.

And after the first CPU and the second CPU both feed back a handover preparation completion message to the mobility management unit, the mobility management unit sends a front-end handover notification for the target UE to the front-end transmission network.

And the front-end transmission network updates routing information and replaces the first CPU pointed by the routing information with the second CPU. And the AP accessed by the target UE sends uplink data to the second CPU according to the updated routing information. The source service CPU refers to a first CPU currently connected with the UE, and the destination service CPU refers to a second CPU to which the UE needs to be switched. Specifically, the mobility-related measurement data may include: the signal strength, signal quality, UE location information, etc. of the UE received by each AP. Taking the signal strength as an example, the mobility management unit determines whether to perform handover according to the strength of the signal received by each AP and the connection condition between the AP and the CPU. Such as: the measured signal strength of the AP within the service range of CPU2 is greater than the AP within the service range of CPU1, indicating that CPU2 serves the UE better than CPU1. For the APs in the overlapping coverage areas of the CPUs 1 and 2, if the AP with high received signal strength is closer to the CPU2, it also means that the CPU2 serves the UE better than the CPU1.

When it is determined that handover is required, handover preparation may be performed first, for example: for the destination service CPU, handover preparation includes resource allocation, UE context establishment, and the like. For the source serving CPU, handover preparation includes UE state transition and the like.

An embodiment of the present invention further provides a data transmission system based on a distributed cellular-free network, as shown in fig. 2, 4, and 5, where the system includes: at least 2 CPUs, each CPU corresponding to at least 2 APs, UE accessing the APs, a front end transmission network and a mobility management unit.

Each CPU is connected with an AP in a service range, the overlapping area is formed when the service ranges of more than 1 CPU are overlapped, the data interaction between the AP in the overlapping area and at least 2 CPUs serving the overlapping area is realized, and when the UE is in the overlapping area, the data interaction is carried out between the AP in the overlapping area and the first CPU.

And the mobility management unit is used for taking the UE which moves as the target UE to be switched and starting to execute the switching process.

The front-end transmission network is used for updating routing information after the UE moves, wherein the routing information points to a CPU (central processing unit) of the UE which currently establishes data interaction.

Specifically, the AP in the overlapping area is connected to the CPU through the front-end transmission network. And the AP outside the overlapping area is directly connected with the CPU, or the AP outside the overlapping area is connected with the CPU through the front-end transmission network.

Further, the mobility management unit is configured to receive first mobility-related measurement data sent by the first CPU and second mobility-related measurement data sent by the second CPU, and detect whether a handover condition is satisfied. And when the switching condition is met, the mobility management unit sends a switching preparation notice to the first CPU and the second CPU, wherein one part of the service range of the first CPU is overlapped with one part of the service range of the second CPU, and an AP in the overlapped service range establishes a data channel with the first CPU and the second CPU through a forwarding network. The first CPU and the second CPU are both used for feeding back a switching preparation completion message to the mobility management unit. The mobility management unit is further configured to send a front-end handover notification for the target UE to the front-end transport network. The front-end transmission network is used for updating routing information and replacing the first CPU pointed by the routing information with the second CPU. And the AP accessed by the target UE is used for sending the uplink data to the second CPU according to the updated routing information.

Compared with the existing scheme, the embodiment has the following advantages on the premise of realizing the distributed deployment without the cellular network: 1. the cooperation among CPU nodes is not needed, and the complexity of control is greatly reduced; 2. fully multiplexing the existing network architecture, algorithm implementation and processing flow; 3. because data transmission between the CPUs is not required, no additional delay is introduced, and thus a high-quality transmission network between the CPUs is not required.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus embodiment, since it is substantially similar to the method embodiment, it is relatively simple to describe, and reference may be made to some descriptions of the method embodiment for relevant points. The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1.A data transmission method based on a distributed cellular-free network is characterized by comprising the following steps:

acquiring the position of a user terminal;

when the user terminal is in an overlapping area, performing data interaction with a first CPU through a wireless access point in the overlapping area, wherein each CPU is connected with the wireless access point in a service range, the overlapping area is formed when the service ranges of more than 1 CPU are overlapped, and the wireless access point in the overlapping area realizes data interaction with at least 2 CPUs serving the overlapping area;

after the user terminal moves, the mobility management unit modifies routing information of a front-end transmission network and routes uplink data of the user terminal to a second CPU, wherein one part of a service range of the first CPU is overlapped with one part of a service range of the second CPU, and a wireless access point in the overlapped service range establishes a data channel with the first CPU and the second CPU through a forwarding network.

2. The method of claim 1, wherein the wireless access points in the overlapping region are connected to a CPU through the front-end transport network;

and the wireless access point outside the overlapping area is directly connected with the CPU, or the wireless access point outside the overlapping area is connected with the CPU through the front-end transmission network.

3. The method of claim 1, wherein the data transmitted over the front-end transport network comprises:

in the downlink transmission process, bit data before or after encoding, or IQ data after encoding and modulation, or frequency domain IQ data after pre-encoding;

and in the uplink transmission process, IQ data after coherent combination or log-likelihood ratio data after detection and demodulation.

4. The method according to claim 1 or 3, wherein in the process of data interaction with the CPU through the wireless access point in the overlapping area, the method further comprises:

and separating the received uplink data of all the user terminals to obtain the uplink data of each user terminal, wherein the separation operation is performed at the wireless access point or at the expansion unit.

5. The method of claim 4, further comprising:

when a user terminal is in an overlapping area, performing data interaction with a first CPU through at least 1 wireless access point in the overlapping area, after receiving uplink data sent by the user terminal, respectively transmitting the received uplink data of the user terminal to the first CPU, wherein the corresponding relation between the user terminal and the CPU which is currently established with the data interaction is recorded in routing information configured by the front-end transmission network.

6. The method of claim 1, wherein after the ue moves, the mobility management unit takes the moving ue as a target ue to be handed over, and starts to perform a handover procedure, comprising:

the mobility management unit receives first mobility-related measurement data sent by a first CPU and second mobility-related measurement data sent by a second CPU, and detects whether a switching condition is met;

when the switching condition is satisfied, the mobility management unit sends a switching preparation notification to the first CPU and the second CPU;

after the first CPU and the second CPU both feed back a handover preparation completion message to the mobility management unit, the mobility management unit sends a front-end handover notification for the target user terminal to the front-end transmission network;

the front-end transmission network updates routing information and replaces the first CPU pointed by the routing information with the second CPU;

and the wireless access point accessed by the target user terminal sends uplink data to the second CPU according to the updated routing information.

7. A data transmission system based on a distributed cellular-free network, the system comprising: at least 2 CPUs, at least 1 wireless access point corresponding to each CPU, a user terminal accessing the wireless access point, a front-end transmission network and a mobility management unit;

each CPU is connected with a wireless access point in a service range, an overlapping area is formed when the service ranges of more than 1 CPU are overlapped, data interaction is realized between the wireless access point in the overlapping area and at least 2 CPUs serving the overlapping area, and data interaction is carried out between the wireless access point in the overlapping area and a first CPU when a user terminal is in the overlapping area;

a mobile management unit, which is used for taking the mobile user terminal as a target user terminal to be switched and starting to execute a switching process;

the front-end transmission network is used for updating routing information after the user terminal moves, wherein the routing information points to a CPU (central processing unit) of the user terminal which currently establishes data interaction.

8. The system of claim 7, wherein the wireless access points in the overlapping region are connected to the CPU through the front end transport network;

9. The system according to claim 7 or 8, wherein the mobility management unit is configured to receive first mobility-related measurement data sent by a first CPU and second mobility-related measurement data sent by a second CPU, and detect whether a handover condition is satisfied; when the switching condition is met, the mobility management unit sends a switching preparation notice to the first CPU and the second CPU, wherein one part of the service range of the first CPU is overlapped with one part of the service range of the second CPU, and a wireless access point in the overlapped service range establishes a data channel with the first CPU and the second CPU through a forwarding network;

the first CPU and the second CPU are both used for feeding back a switching preparation completion message to the mobility management unit; the mobility management unit is further configured to send a front-end handover notification for the target user terminal to the front-end transport network;

the front-end transmission network is used for updating routing information and replacing the first CPU pointed by the routing information with the second CPU;

and the wireless access point accessed by the target user terminal is used for sending the uplink data to the second CPU according to the updated routing information.

10. A storage medium, characterized in that a computer program or instructions are stored which, when executed by a computer, implement the method according to any one of claims 1 to 6.