A cross-satellite communication switching method based on mobile groups

Abstract

The present invention proposes a cross-satellite communication switching method based on a mobile group, which belongs to the field of communication technology. The present invention regards the mobile group as a whole, and multiple mobile terminals inside can use internal wireless or wired links to communicate; externally, one of the multiple mobile terminals in the mobile group is used to realize cross-satellite external communication, and two of the mobile terminals are used to realize cross-satellite communication switching. During switching, the main mobile terminal and the mobile terminal to be switched in the mobile group are used to establish two transmission channels with the original communication satellite and the target communication satellite respectively. Before switching, the original transmission channel is used for service transmission, and after switching, the new transmission channel is used for service transmission, thereby ensuring uninterrupted external service transmission of the mobile group. In the cross-satellite communication switching process of the mobile group of the present invention, the entire mobile group only performs one cross-satellite switching, and there is no need for each mobile terminal to perform cross-satellite switching, which reduces the number of switching times.

Description

Technical Field

[0001] The invention relates to an inter-satellite communication switching method based on a mobile group, and belongs to the technical field of communications. Background Art

[0002] Since the coverage area of ​​a single geosynchronous orbit satellite (high-orbit GEO satellite) or non-geosynchronous orbit satellite (such as medium-orbit MEO satellite and low-orbit LEO satellite) is limited and it is difficult to achieve coverage of a large area or even the whole world, many geosynchronous orbit satellite systems and non-geosynchronous orbit satellite systems have begun to deploy multiple communication satellites or constellations to increase the coverage area and even achieve global coverage.

[0003] In a system consisting of multiple communication satellites, different satellites use different satellite beams to cover different areas. When a satellite mobile terminal moves within the coverage area of ​​a multi-satellite satellite communication system, it inevitably faces the problem of inter-satellite handover. The power value is highest at the center of the satellite beam and gradually decreases towards the beam edge. As a mobile terminal moves from the center of communication satellite beam A to the adjacent communication satellite beam B, the signal strength between the mobile terminal and communication satellite beam A gradually decreases, while the signal strength with communication satellite beam B gradually increases. When this reaches a certain level, the mobile terminal needs to switch to using the satellite resources of communication satellite beam B and no longer use the satellite resources of communication satellite beam A.

[0004] Since most satellite mobile terminals use directional antennas, and different communication satellites are located in different positions, the satellite mobile terminal must adjust the antenna pointing (if the phased array antenna needs to adjust the beam pointing) before establishing the satellite communication channel, which will cause service interruption. To ensure uninterrupted service, a single mobile terminal needs to be equipped with two directional antennas (or one phased array antenna with two beams). One of the directional antennas (or one beam of the phased array antenna) is used to communicate with the original communication satellite, while the other directional antenna (or one beam of the phased array antenna) is used to establish a new transmission channel with the target communication satellite. After the new transmission channel is established, the service transmission can be switched to the new transmission channel to complete the inter-satellite communication handover.

[0005] However, this approach not only requires each mobile terminal to be equipped with two directional antennas (or one phased array antenna with two beams), but also makes each mobile terminal independent of each other, greatly increasing the number of cross-satellite communication switches. Summary of the Invention

[0006] In light of this, the present invention proposes a method for inter-satellite communication handover based on a mobile group. This method treats the mobile group as a whole, requiring only a single inter-satellite handover for the entire group, rather than requiring each mobile terminal to perform an inter-satellite handover. This reduces the number of handovers and allows each mobile terminal to be configured with only one directional antenna (or one phased array antenna with one beam).

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A mobile group-based inter-satellite communication handover method comprises: forming a mobile group with multiple mobile terminals, wherein the mobile terminals within the mobile group communicate via wireless or wired links; the mobile group as a whole uses one mobile terminal as a master mobile terminal to implement inter-satellite external communication for the entire mobile group; and performing inter-satellite communication handover when the mobile group moves into the coverage area of ​​another communication satellite. The method specifically comprises the following steps:

[0009] Step 1: Select a mobile terminal to be switched within the mobile group to establish a new transmission channel with another communication satellite;

[0010] Step 2: The active mobile terminal sends a mobile group handover request message to the ground control center, including information of the active mobile terminal, the mobile terminal to be handed over, the original communication satellite, the target communication satellite, and other mobile terminals;

[0011] Step 3: The control center allocates channel resources of the target communication satellite or pre-planned channel resources. If the channel resources can be allocated, step 4 is executed; if the channel resources cannot be allocated, the inter-satellite communication handover fails, and step 6 is executed.

[0012] Step 4: The mobile terminal to be switched establishes a new transmission channel with the target communication satellite, and continuously detects the channel quality and compares it with the original transmission channel quality;

[0013] Step 5: If the quality of the new transmission channel is better than the original transmission channel within a period of time, the external service transmission within the mobile group is switched to the new transmission channel, the mobile terminal to be switched is designated as the new primary mobile terminal, and the original transmission channel resources are reclaimed. The switching is successful and this process ends. If the quality of the new transmission channel is always not better than the original transmission channel quality, the inter-satellite handover fails and step 6 is executed.

[0014] Step 6: After the inter-satellite handover fails, the mobile group continues to use the original transmission channel for external business transmission; if there are allocated new transmission channel resources, the resources are recovered and this process ends.

[0015] Furthermore, the mobile group as a whole uses one of its mobile terminals as the primary mobile terminal to achieve cross-satellite external communication of the entire mobile group. Specifically, the non-primary mobile terminals in the mobile group communicate with the primary mobile terminal through wireless or wired links in a direct or multi-hop manner. The primary mobile terminal communicates directly with the communication satellite, and the non-primary mobile terminals all achieve indirect communication with the communication satellite through the primary mobile terminal.

[0016] Furthermore, the active mobile terminal and the mobile terminal to be switched in the mobile group are each configured with only one satellite antenna or one beam phased array antenna.

[0017] The beneficial effects of the present invention are:

[0018] 1. In real-world scenarios, in addition to the free movement of individual mobile terminals (users), many mobile terminals will have identical or very similar movement trajectories. Therefore, they can be considered as a whole, forming a mobile group (for example, a convoy of cars, different train carriages, an aircraft formation, or a group of multiple co-orbiting remote sensing / reconnaissance satellites in low-orbit). Multiple mobile terminals within a mobile group can communicate using internal wireless or wired links (or networks). Externally, a single active mobile terminal within the mobile group can achieve inter-satellite communication. Inter-satellite communication handover can also be achieved using two mobile terminals within the mobile group, ensuring uninterrupted external communication for the entire group. Traditional inter-satellite handover methods for individual mobile terminals cannot be simply applied to inter-satellite handover for mobile groups.

[0019] 2. In the present invention, the entire mobile group only needs to perform one inter-satellite handover, and each mobile terminal does not need to perform an inter-satellite handover, thereby reducing the number of handovers.

[0020] 3. The active mobile terminal and the mobile terminal to be switched in the mobile group only need to be equipped with one satellite antenna (or one-beam phased array antenna) to achieve the soft switching function. Unlike the traditional soft switching method, each mobile terminal does not need to be equipped with two satellite antennas (or two-beam phased array antennas), saving the number of equipment and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of an application scenario of the method according to an embodiment of the present invention;

[0023] Figure 3 It is a timing diagram of the method according to the embodiment of the present invention. Implementation Method

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] A cross-satellite communication switching method based on mobile groups, its application scenarios are as follows Figure 2 As shown in the figure, the entire satellite communication system consists of a mobile group, a source communication satellite, a target communication satellite, a ground gateway, a network control center, and an external network. Each communication satellite lands information through one or more ground gateways. Each ground gateway is connected to an external network (such as the internet), enabling the mobile group to communicate with the external network. Each ground gateway is connected to the control center via ground fiber optic links. The network control center is responsible for allocating satellite resources. The mobile group communicates with the control center via communication satellites and ground gateways.

[0026] The specific process of this method is as follows Figure 1 and Figure 3 As shown, the specific steps include:

[0027] (1) The mobile group selects an external main mobile terminal to establish a transmission channel with the original communication satellite. Each mobile terminal within the mobile group can communicate with the external main mobile terminal directly or through other mobile terminals through internal wireless or wired links, thereby using the satellite communication transmission channel of the main mobile terminal to achieve communication with the external network; the control center sends the satellite system ephemeris information to the main mobile terminal;

[0028] (2) When the mobile group moves to the coverage area of ​​another communication satellite (target communication satellite), cross-satellite communication switching is required;

[0029] (3) In order to ensure uninterrupted external communication of the mobile group, the main mobile terminal presides over the selection of another mobile terminal to be switched within the group to establish a new transmission channel with the target communication satellite. After the election is completed, the main mobile terminal broadcasts the election result to each mobile terminal in the mobile group through an internal link or network; when selecting the mobile terminal to be switched, priority is given to mobile terminals with strong capabilities as the mobile terminal to be switched, for example, mobile terminals with large energy, large external satellite antenna EIRP and G\T values ​​are given priority.

[0030] (4) The mobile group (primary mobile terminal) sends a group handover request message to the ground control center. The request message includes information about the primary mobile terminal, the mobile terminal to be handed over, the original communication satellite, the target communication satellite, and other mobile terminals.

[0031] (5) The control center allocates channel resources of the target communication satellite or pre-planned channel resources. If the channel resources can be allocated, step (6) is executed; if the channel resources cannot be allocated, the inter-satellite communication handover fails, and step (8) is executed.

[0032] (6) The mobile terminal to be switched establishes a new transmission channel with the target communication satellite and continuously detects the channel quality (such as signal strength); the main mobile terminal continuously sends the real-time parameters of the original transmission channel quality to the mobile terminal to be switched through the internal line or network, and the mobile terminal to be switched continuously compares the quality of the new transmission channel with the quality of the original transmission channel;

[0033] (7) Within a period of time (for example, it can be set to the length of the overlapping area of ​​the original communication satellite beam and the target communication satellite beam in the moving direction of the mobile group / the estimated average moving speed of the mobile group), if it is found that the quality of the new transmission channel is better than the quality of the original transmission channel, it indicates that switching can be performed, then the external service transmission within the group is switched to the new transmission channel, the mobile terminal to be switched is designated as the new main mobile terminal, and the original transmission channel resources are recovered, the switching is successful, and the process ends; if the quality of the new channel is always not better than the quality of the original transmission channel, it indicates that an abnormal situation has occurred, such as the mobile group temporarily changes its moving direction or the channel quality of the target mobile satellite deteriorates, and the inter-satellite switching fails;

[0034] (8) After the inter-satellite handover fails, the mobile group continues to use the original transmission channel for external business transmission; if there are new transmission channel resources allocated, the resources are recovered and the process ends.

[0035] This method treats the mobile group as a single entity. Multiple mobile terminals within the group can communicate using internal wireless or wired links (or networks). Externally, one of the multiple mobile terminals in the group can communicate across satellites, while two of the mobile terminals can perform inter-satellite handover. During inter-satellite handover, the entire mobile group undergoes a single inter-satellite handover, eliminating the need for individual mobile terminals to perform a handover, thus reducing the number of handovers.

[0036] Mobile group inter-satellite communication handover utilizes a soft handover approach. This involves establishing two transmission channels with the original and target satellites, respectively, using the active mobile terminal within the mobile group and the target mobile terminal to be handed over. Service transmission occurs over the original channel before the handover, and over the new channel after the handover, ensuring uninterrupted external service transmission for the group. This approach allows the active and target mobile terminals within the mobile group to achieve soft handover with only one satellite antenna (or one-beam phased array antenna), rather than two satellite antennas (or two-beam phased array antennas) per mobile terminal, as is required with traditional soft handover.

Claims

1. A method for switching inter-satellite communications based on a mobile group, characterized in that: Multiple mobile terminals are organized into a mobile group, and the mobile terminals within the mobile group communicate via wireless or wired links. The mobile group is treated as a whole, and one of the mobile terminals is used as the primary mobile terminal to achieve inter-satellite external communication for the entire mobile group. When the mobile group moves into the coverage area of ​​another communication satellite, inter-satellite communication switching is performed, specifically including the following steps: Step 1: Select a mobile terminal to be switched within the mobile group to establish a new transmission channel with another communication satellite; Step 2: The active mobile terminal sends a mobile group handover request message to the ground control center, including information of the active mobile terminal, the mobile terminal to be handed over, the original communication satellite, the target communication satellite, and other mobile terminals; Step 3: The control center allocates channel resources of the target communication satellite or pre-planned channel resources. If the channel resources can be allocated, step 4 is executed; if the channel resources cannot be allocated, the inter-satellite communication handover fails, and step 6 is executed. Step 4: The mobile terminal to be switched establishes a new transmission channel with the target communication satellite, and continuously detects the channel quality and compares it with the original transmission channel quality; Step 5: If the quality of the new transmission channel is better than the original transmission channel within a period of time, the external service transmission within the mobile group is switched to the new transmission channel, the mobile terminal to be switched is designated as the new primary mobile terminal, and the original transmission channel resources are reclaimed. The switching is successful and this process ends. If the quality of the new transmission channel is always not better than the original transmission channel quality, the inter-satellite handover fails and step 6 is executed. Step 6: After the inter-satellite handover fails, the mobile group continues to use the original transmission channel for external business transmission; if there are allocated new transmission channel resources, the resources are recovered and this process ends.

2. The inter-satellite communication switching method based on mobile groups according to claim 1, characterized in that: The mobile group is taken as a whole, and one of the mobile terminals is used as the main mobile terminal to realize cross-satellite external communication of the entire mobile group. Specifically, the non-main mobile terminals in the mobile group communicate with the main mobile terminal through wireless or wired links in a direct connection or multi-hop manner. The main mobile terminal communicates directly with the communication satellite, and the non-main mobile terminals all realize indirect communication with the communication satellite through the main mobile terminal.

3. The inter-satellite communication switching method based on mobile groups according to claim 1, characterized in that: The active mobile terminal and the mobile terminal to be switched in the mobile group are both equipped with only one satellite antenna or one beam phased array antenna.

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