CN117527049A

CN117527049A - Method, device and system for switching anchor point UPF (unified Power flow) in low-orbit satellite communication system

Info

Publication number: CN117527049A
Application number: CN202311618782.0A
Authority: CN
Inventors: 商科峰; 刘田; 张毅; 马松; 陈颖; 邹钦羊
Original assignee: CETC 10 Research Institute
Current assignee: CETC 10 Research Institute
Priority date: 2023-11-29
Filing date: 2023-11-29
Publication date: 2024-02-06

Abstract

The invention discloses a method, a device and a system for switching anchor UPF under a low orbit satellite communication system, which belong to the field of satellite communication and comprise the following steps: firstly, a public network IP address is allocated for a terminal user, and the public network IP address is kept unchanged when anchor point UPF changes occur at the terminal; secondly, when the satellite serving the terminal is switched from the source gateway station A to the destination gateway station B, and the terminal also follows the satellite to switch, the UPF of the gateway station A deletes the route, and simultaneously transmits the session context of the terminal data surface to the UPF of the gateway station B side and the gateway station B issues the route. And switching the anchor point UPF through the release of the new route and the deletion of the old route. When the anchor point UPF switching happens, the terminal data plane IP remains unchanged, and only the session context, the release route and the deletion route are required to be dynamically synchronized. The scheme of the invention does not need to forward data between the source side UPF and the destination side UPF, does not introduce forwarding delay, and does not occupy forwarding bandwidth.

Description

Method, device and system for switching anchor point UPF (unified Power flow) in low-orbit satellite communication system

Technical Field

The present invention relates to the field of satellite communications, and in particular, to a method, an apparatus, and a system for switching an anchor point UPF in a low-orbit satellite communications system.

Background

With the vigorous development of low-orbit satellite constellations, more and more low-orbit satellite systems are being built. The related problems of the satellite cross gateway feed link switching scene specific to the low orbit satellite system become an important subject of system scheme research. The problem of switching between the low orbit satellite and the gateway station in a very short time of a user which may occur under the station scene of the low orbit satellite, two conditions exist, namely: a single-star coverage area exists under the satellite cross-signal gateway station feed link switching time, users in the area passively follow the satellite cross-signal gateway station switching, meanwhile, the users at the edge of the single-star area are about to be covered by other satellites, and if other satellites are selected for access, the cross-signal gateway station switching can occur in a very short time; and a second case: users served by other satellites will have to switch to the current satellite because they are about to enter an area covered only by the current satellite, while at the same time the satellite cross-gateway feed link switches, single satellite coverage area users passively follow the satellite cross-gateway switch. Both of the above cases may cause some users to switch back and forth across gateway stations in a very short time, and the user service experience is affected.

Each gateway station has a local UPF that is responsible for handling the user plane traffic. As described in the above scenario, a user in a particular switching band may have a problem of frequent switching across gateway stations. How to ensure the continuity of the part of user traffic. The 3GPP protocol gives several ideas:

SSC mode one: when the access technology or the user position changes, the anchor point of the PDU session is kept unchanged, namely the UPF for executing the anchor point function is not changed;

SSC mode two: the method is that the original PDU session is cut off, then a new PDU session is established with the same data network, and after the new PDU session is established successfully, the new PDU session becomes a new anchor point;

SSC pattern three: then a new PDU session is re-established and a new UPF is used as the anchor point for the PDU session before the original PDU session is released.

For the SSC mode one, as shown in fig. 1, when a user sends a handover from gateway station a to gateway station B, in order to ensure continuity of service, a tunnel needs to be established between an anchor point UPF and a UPF serving the gateway station, and data is forwarded back to the anchor point UPF and then goes out to the public internet via the anchor point UPF. The dedicated bandwidth resources between gateway stations are precious, the capacity is limited, and the backhaul requirement of the data service cannot be met. Thus, in low-orbit satellite communication systems, the first SSC mode is not suitable for overcoming the effects of frequent UPF handoffs.

For the SSC mode two, as shown in fig. 2, when a user switches across gateway stations, in order to ensure continuity of service, it is necessary to repeatedly delete a session between the establishment and an anchor UPF. Repeated deletion of established sessions, re-assignment of IP to users, also presents a brief interruption of traffic, which is intolerable to users in the handover zone. Thus, in low-orbit satellite communication systems, SSC mode two is not suitable for overcoming the effects of frequent UPF handoffs.

For the SSC mode three, as shown in fig. 3, when a user makes a handover across gateway stations, in order to ensure continuity of service, a session with a destination UPF needs to be established in advance. For the same user, there are two IP routing connections between the application at the same time. Corresponding processing needs to be carried out on IP change and state transition, and meanwhile, data migration and merging are carried out on the side of application, so that the method is only suitable for special scenes. Thus, in low-orbit satellite communication systems, SSC mode three is also unsuitable for overcoming the effects of frequent UPF handoffs.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method, a device and a system for switching an anchor point UPF in a low-orbit satellite communication system, which do not need to forward data between a source side UPF and a destination side UPF, do not introduce forwarding delay and do not occupy forwarding bandwidth.

The invention aims at realizing the following scheme:

a method for anchor point UPF handoff in a low orbit satellite communication system, comprising the steps of:

step 1, an IP address is allocated for a terminal user, wherein the IP address is a public network IP address, and the IP address is kept unchanged when anchor point UPF changes occur at the terminal;

step 2, when the satellite B serving the terminal is switched from the source gateway station A to the destination gateway station B, and the terminal also follows the satellite B to switch, the UPF of the gateway station A side deletes the route, and simultaneously transmits the session context of the terminal data surface to the UPF of the gateway station B side and the UPF release route of the gateway station B side;

step 3, completing the switching of the anchor UPF through the release of the new route and the deletion of the old route; when the anchor point UPF switching happens, the terminal data plane IP remains unchanged, dynamically synchronizes the session context, issues the route and deletes the route.

Further, in step 1, the public network IP address is a public network address of Ipv 6.

Further, in step 2, the UPF on the gateway station a deletes the route, specifically, the UPF on the gateway station a deletes the route when the handover occurs by predicting the time when the terminal follows the satellite b to make the handover.

Further, in step 3, the switching of the anchor point UPF is completed through the release of the new route and the deletion of the old route; when the anchor point UPF switching happens, the terminal data plane IP remains unchanged, and only needs to dynamically synchronize the session context, release the route and delete the route, which comprises the following steps:

as satellite b moves, the terminal leaves the coverage of satellite b; the terminal can be switched between satellites, and the terminal is switched to the coverage area of the satellite a; satellite a also switches the terminal-anchored UPF back to the gateway station a UPF within the service range of gateway station a; the side A of the gateway station issues the route, and the side B of the gateway station deletes the route; the UPF of gateway a is updated synchronously according to the session context of the terminal in the UPF of gateway B.

An apparatus for an anchor UPF handoff in a low orbit satellite communication system, comprising a processor and a memory in which a program is stored that when loaded by the processor performs the method of any of the above claims.

A system for anchor UPF handoff in a low-orbit satellite communication system, comprising an apparatus as described above.

The beneficial effects of the invention include:

the invention innovatively contemplates a mode that a terminal adopts a fixed IP gateway station to release a new route and delete an old route when switching across gateway stations under a low-orbit satellite communication system, and can realize anchor point UPF switching. Compared with the prior art, the scheme of the invention has the following technical progress:

1) The public network IP avoids the re-establishment of IP connection between the caused and applied IP after the terminal switches the anchor point UPF;

2) The accurate coordination of releasing the new route and deleting the old route can ensure the continuity of the user service of the switching band;

3) The terminal session is anchored on the nearby UPF, the data is directly nearby to the Internet, and the service time delay is low;

4) Data is output to the Internet on the nearby UPF, forwarding between the source side UPF and the destination side UPF is not needed, and the special line bandwidth between the source side UPF and the destination side UPF is not occupied.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.

FIG. 1 is a schematic diagram of an anchor switching scheme for SSC mode;

FIG. 2 is a schematic diagram of a SSC mode two-anchor switching scheme;

fig. 3 is a schematic diagram of a three anchor point switching scheme in SSC mode;

fig. 4 is a schematic diagram of a multi-anchor scheme under SSC routing broadcast according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a multi-anchor example under SSC routing broadcast according to an embodiment of the present invention.

Detailed Description

All of the features disclosed in all of the embodiments of this specification, or all of the steps in any method or process disclosed implicitly, except for the mutually exclusive features and/or steps, may be combined and/or expanded and substituted in any way.

In the inventive concept, the inventors of the present invention consider that: in a low-orbit satellite communication system, the switching scene is regular and can be judged, unlike a ground mobile communication network. For handover across gateway stations, the network side can be accurately predicted. By pre-judging the switching time, accurately judging the time when the switching is about to occur, synchronizing the session context of the terminal and issuing a new route announcement at the destination UPF side, simultaneously maintaining the session context at the source side, and deleting the old route at the UPF side so as to achieve the route update between the destination UPF and the public network application server.

Under the above conception, when the cross-gateway station is switched in the low-orbit satellite communication system, the terminal adopts a mode of fixed IP gateway station route broadcasting, an anchor point UPF switching scheme is realized, and route release and route deletion are carried out based on the characteristic of prejudgement of satellite switching, so that the service continuity is ensured; by pre-judging the switching time, accurately judging the time when the switching is about to occur, synchronizing the session context of the terminal and issuing a new route announcement at the destination UPF side, simultaneously maintaining the session context at the source side, and deleting the old route at the UPF side so as to achieve the route update between the destination UPF and the public network application server.

In a specific embodiment, as shown in fig. 5, the beijing gateway station and the chu gateway station respectively correspond to independent UPFs, so that the configuration is convenient for data to come out to the internet, and the time delay of a data plane is reduced. The two satellites a, b alternately cover the end-user under the handoff band. The feeder link between the beijing gateway station and the chu gateway station switches the user terminal with a single star coverage area under the band, and frequent situations of switching anchor point UPF exist. The implementation steps of the technical scheme of the invention are as follows:

in step 1, as shown in fig. 5 (a), when the satellite b is operating at the position C, the terminal of the switching band is in the beam coverage area of the satellite b, and at this time, the satellite b is connected to the beijing gateway station. The Beijing gateway station allocates a fixed IP address to the terminal, and the public network address of the Ipv6 is adopted in consideration of the fact that the public network address of the Ipv4 is relatively small.

Step 2, as shown in fig. 5 (b), the feed link of the satellite b is switched with the movement of the satellite b, and the feed link is switched from the beijing gateway station to the chu gateway station. The user in the single satellite coverage zone will follow satellite b to switch to the Chu-Xiong gateway station. The anchor UPF of these end users also switches from the UPF of the beijing gateway station to the UPF of the chu gateway station.

At this time, the routing relationship of the terminal changes. The service data of the terminal on the public internet is sent from the application server to the Beijing gateway station and then sent to the terminal. After switching, the routing relationship becomes from an application server on the public internet, and sends to the Chu-Xiong gateway station and then to the terminal. Therefore, it is necessary to delete the routing relationship at the Beijing gateway station. And transmitting the session context of the terminal in the UPF of the Beijing gateway station to the UPF of the Chu-Xiong gateway station, and simultaneously releasing a new route by the Chu-Xiong gateway station.

Step 3, as shown in fig. 5 (C), the position of the satellite b moves from point C to point D as the satellite b moves. At the same time, the position of satellite a moves from point a to point B. When satellite b is at point D, the user of the handoff strap gradually leaves the coverage of satellite b and enters the coverage of satellite a. At this point the user switching the band needs to switch to satellite a to continue the service. Because the satellite a is still in the coverage area of the Beijing gateway station at this time, when the user switching the band switches to the satellite a to do business, the anchor point UPF also switches from the UPF of the Chu-Xuan gateway station to the UPF of the Beijing gateway station. In this process, both sessions of the data plane of the terminal are kept updated synchronously.

The terminal switching the band needs to delete the route at the Chu-Xe gateway station and issue the route at the Beijing gateway station. After the switching, the session of the terminal data surface is kept synchronously updated, and only the release and the deletion of the route are needed.

The distance between the Beijing gateway station and the Chu-Xiong gateway station is about 2200 km, the bandwidth of the special line is about hundred M, only the transmission of some management and control data on the special line is considered, and the transmission requirement of service data is not considered. And the data volume of one satellite is approximately about 10Gbps in one direction. The anchor point-unchanged scheme is adopted, so that data is required to be forwarded from a special line, and the capability of the special line can not meet the forwarding requirement at present. Meanwhile, the transmission delay of about 10ms is introduced in the forwarding of the special line. Therefore, by adopting the scheme provided by the invention, the special line is not required to bear the pressure of data forwarding while the service continuity of the terminal is ensured, and meanwhile, additional forwarding time delay is not introduced.

It should be noted that, within the scope of protection defined in the claims of the present invention, the following embodiments may be combined and/or expanded, and replaced in any manner that is logical from the above specific embodiments, such as the disclosed technical principles, the disclosed technical features or the implicitly disclosed technical features, etc.

Example 1

Example 2

On the basis of embodiment 1, in step 1, the public network IP address is a public network address of Ipv 6.

Example 3

Based on embodiment 1, in step 2, the UPF on the gateway station a side deletes the route, specifically, the UPF on the gateway station a side deletes the route when the handover occurs by predicting the time when the terminal follows the handover made by the satellite b.

Example 4

Based on embodiment 1, in step 3, the switching of the anchor point UPF is completed by the release of the new route and the deletion of the old route; when the anchor point UPF switching happens, the terminal data plane IP remains unchanged, and only needs to dynamically synchronize the session context, release the route and delete the route, which comprises the following steps:

Example 5

An apparatus for anchor point UPF handoff in a low orbit satellite communication system, comprising a processor and a memory, in which a program is stored which when loaded by the processor performs the method of any one of claims 1 to 4.

Example 6

A system for anchor UPF handoff in a low-orbit satellite communication system, comprising an apparatus as in embodiment 5.

The units involved in the embodiments of the present invention may be implemented by software, or may be implemented by hardware, and the described units may also be provided in a processor. Wherein the names of the units do not constitute a limitation of the units themselves in some cases.

According to an aspect of embodiments of the present invention, there is provided a computer program product or computer program comprising computer instructions stored in a computer readable storage medium. The computer instructions are read from the computer-readable storage medium by a processor of a computer device, and executed by the processor, cause the computer device to perform the methods provided in the various alternative implementations described above.

As another aspect, the embodiment of the present invention also provides a computer-readable medium that may be contained in the electronic device described in the above embodiment; or may exist alone without being incorporated into the electronic device. The computer-readable medium carries one or more programs which, when executed by the electronic device, cause the electronic device to implement the methods described in the above embodiments.

Claims

1. A method for switching an anchor point UPF in a low orbit satellite communication system, comprising the steps of:

2. The method for switching anchor UPF in a low-orbit satellite communication system according to claim 1, wherein in step 1, the public network IP address is a public network address of Ipv 6.

3. The method for switching between anchor points UPF in a low-orbit satellite communication system according to claim 1, wherein in step 2, the UPF on the a side of the gateway station deletes the route, specifically, the UPF on the a side of the gateway station deletes the route when the switching occurs by prejudging the moment that the terminal follows the switching of the satellite b.

4. The method for switching an anchor point UPF in a low-orbit satellite communication system according to claim 1, wherein in step 3, the switching of the anchor point UPF is completed by the release of the new route and the deletion of the old route; when the anchor point UPF switching happens, the terminal data plane IP remains unchanged, and only needs to dynamically synchronize the session context, release the route and delete the route, which comprises the following steps:

5. An apparatus for an anchor UPF handoff in a low orbit satellite communication system, comprising a processor and a memory, wherein the memory stores a program that when loaded by the processor performs the method of any one of claims 1-4.

6. A system for an anchor UPF handoff in a low orbit satellite communication system comprising the apparatus of claim 5.