A terminal mobility management method based on MF-TDMA and DVB-RCS2

Abstract

The present invention discloses a terminal mobility management method based on MF-TDMA and DVB-RCS2, including: selecting a satellite terminal in a communication network, obtaining the control time slots of an interactive network and an adjacent interactive network, and simultaneously obtaining the service time slots of the interactive network, thereby initiating service communication; moving the satellite terminal to an adjacent interactive network, switching the forward channel, using the control time slot of the adjacent interactive network, and directly sending a service time slot application through the control time slot; setting a timeout time for the service time slots obtained by the satellite terminal in different interactive networks, and when it is detected that the state of the satellite terminal in the interactive network exceeds the set time, releasing the service time slot in the interactive network, and if it does not exceed, switching the corresponding forward channel and jumping into the service communication state. The present invention aims to avoid the problem of re-login of the user terminal when switching beams and the problem of frequent service interruptions through the above method.

Description

Technical Field

[0001] The invention relates to the field of satellite communication and discloses a terminal mobility management method based on MF-TDMA and DVB-RCS2. Background Art

[0002] Satellite communication technology is an important wireless communication method, which can be used as an emergency communication method after natural disasters such as earthquakes and tsunamis. MF-TDMA (Multi-Frequency Time Division Multiple Access) is a hybrid multiple access method that combines FDMA and TDMA systems. As the mainstream system currently adopted by broadband multimedia satellite communication systems, MF-TDMA allows user terminals to share a series of carriers with different rates, and each carrier is divided into time slots. Through comprehensive scheduling of time and frequency two-dimensional resources, flexible resource allocation is achieved. DVB-RCS2 is a standard protocol for implementing the MF-TDMA system. In this protocol, the terminal usually needs to log in to an IN (interactive network), and then the NCC (Network Control Center) allocates the service time slot in the IN to it. The terminal sends service data on the time slot allocated by the NCC. This method has good support for ordinary fixed stations, but for vehicle-mounted stations and airborne stations with strong mobility, there may be frequent beam switching problems. Usually, the terminal needs to re-login each time it switches, and the service time slot also needs to be reallocated. There is also a ping-pong switching problem, which may cause frequent interruptions of services for such terminal users during use.

[0003] In DVB-RCS2, the protocol defines the terminal's time slot acquisition method, network login process and state transition rules. After the small station (satellite terminal) is normally powered on, it usually needs to go through the following steps: Figure 1 The process shown in the figure adds interactive network and communication, and the whole process takes about ten seconds. Therefore, in the scenario of re-login in different beam switching, each switch will take at least ten seconds to restore business communication. If the user ping-pongs at the edge of the beam, it is very likely that the service will be interrupted for a long time for the user, which will greatly affect the user experience. Especially under the beam planning of modern high-throughput satellites, the beams on the user side are all small beams, which exacerbates the occurrence of such situations. Summary of the invention

[0004] Purpose of the invention: To provide a terminal mobility management method based on MF-TDMA and DVB-RCS2 protocols to solve the above problems.

[0005] Technical solution: A terminal mobility management method based on MF-TDMA and DVB-RCS2, comprising the following steps:

[0006] S1. Select a satellite terminal in the communication network, build an interactive network of multiple beams based on the communication network, and the satellite terminal logs in to the interactive network of the current beam to obtain the control time slots in the interactive network of the current beam and the interactive network of the adjacent beam;

[0007] S2. The satellite terminal switches to an adjacent beam, logs in to the interactive network of the adjacent beam, and directly adopts the control time slot in the interactive network of the adjacent beam. The satellite terminal sends a service time slot application through the control time slot to obtain the service time slot. The satellite terminal initiates service communication through the service time slot, and at the same time re-obtains the control time slots of the surrounding beams in the interactive network according to the position of the switched beam.

[0008] According to one aspect of the present application, after the satellite terminal switches to an adjacent beam, it initiates service communication through a service time slot by performing forward alignment, obtaining forward signaling, which includes time slot planning, directly applying for a service time slot, and realizing service communication.

[0009] According to one aspect of the present application, when a satellite terminal switches to an adjacent beam, the satellite terminal directly sends a control burst of the adjacent beam, updates the information of the satellite terminal according to the received control burst of the adjacent beam, and reallocates the control time slots of the surrounding beams in the interactive network.

[0010] According to one aspect of the present application, step S3 is also included:

[0011] S3. The satellite terminal obtains service time slot resources in the interactive network of different beams and sets a timeout period for the service time slot resources. When the satellite terminal sends a control burst, the timeout period of the service time slot resources of the beam in the interactive network is reset. When it is detected that the satellite terminal has not sent a control burst after exceeding the set time, the service time slot resources in the interactive network of the beam are released. When it is detected that the satellite terminal sends a control burst within the set time, the service time slot resources in the interactive network of the beam are directly read and the service communication state is jumped into.

[0012] According to one aspect of the present application, the steps for service communication after the satellite terminal switches to adjacent beams multiple times are specifically: performing forward alignment, obtaining forward signaling, the forward signaling includes time slot planning, and realizing service communication.

[0013] Beneficial effects: This solution proposes a terminal mobility management method based on MF-TDMA and DVB-RCS2 protocols, which is implemented through network planning and TDMA time slot planning, aiming to avoid the problem of re-login of user terminals when switching beams and the problem of frequent service interruptions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1This is a map of the location of the communication terminal for the small station to access the interactive network.

[0015] Figure 2 A terminal location diagram for a small station to move to another interactive network.

[0016] Figure 3 A terminal location diagram for small stations moving back and forth at the edges of different interactive networks.

[0017] Figure 4 This is the satellite terminal business communication flow chart. DETAILED DESCRIPTION

[0018] Satellite communication technology is an important wireless communication method, which can be used as an emergency communication method after natural disasters such as earthquakes and tsunamis. MF-TDMA (Multi-Frequency Time Division Multiple Access) is a hybrid multiple access method that combines FDMA and TDMA systems. As the mainstream system currently adopted by broadband multimedia satellite communication systems, MF-TDMA allows user terminals to share a series of carriers with different rates, and each carrier is divided into time slots. Through comprehensive scheduling of time and frequency two-dimensional resources, flexible resource allocation is achieved. DVB-RCS2 is a standard protocol for implementing the MF-TDMA system. In this protocol, the terminal usually needs to log in to an IN (interactive network), and then the NCC (Network Control Center) allocates the service time slot in the IN to it. The terminal sends service data on the time slot allocated by the NCC. This method has good support for ordinary fixed stations, but for vehicle-mounted stations and airborne stations with strong mobility, there may be frequent beam switching problems. Usually, the terminal needs to re-login each time it switches, and the service time slot also needs to be reallocated. There is also a ping-pong switching problem, which may cause frequent interruptions of services for such terminal users during use.

[0019] In DVB-RCS2, the protocol defines the time slot acquisition method, network login process and state transition rules of the terminal. After the small station is normally powered on, it usually needs to go through the following steps: Figure 1 The process shown in the figure adds interactive network and communication, and the whole process takes about ten seconds. Therefore, in the scenario of re-login in different beam switching, each switch will take at least ten seconds to restore business communication. If the user ping-pongs at the edge of the beam, it is very likely that the service will be interrupted for a long time for the user, which will greatly affect the user experience. Especially under the beam planning of modern high-throughput satellites, the beams on the user side are all small beams, which exacerbates the occurrence of such situations.

[0020] For this situation, this solution proposes a terminal mobility management method based on MF-TDMA and DVB-RCS2 protocol, including the following steps:

[0021] S1. Select a satellite terminal in the communication network, build an interactive network of multiple beams based on the communication network, and the satellite terminal logs in to the interactive network of the current beam to obtain the control time slots in the interactive network of the current beam and the interactive network of the adjacent beam;

[0022] S2. The satellite terminal switches to an adjacent beam, logs in to the interactive network of the adjacent beam, and directly adopts the control time slot in the interactive network of the adjacent beam. The satellite terminal sends a service time slot application through the control time slot to obtain the service time slot. The satellite terminal initiates service communication through the service time slot, and at the same time re-obtains the control time slots of the surrounding beams in the interactive network according to the position of the switched beam.

[0023] In a further embodiment, obtaining the control time slots in the interactive network of the current beam and the interactive network of the adjacent beam in step S1 can be executed in subsequent steps. In step S1, the network control has been allocated, so that when the terminal enters other interactive networks, it does not need to re-enter the network. It can directly detect the control time slot and enter the network state directly.

[0024] When the satellite terminal switches to an adjacent beam, the satellite terminal directly sends a control burst of the adjacent beam, updates the information of the satellite terminal according to the received control burst of the adjacent beam, and reallocates the control time slots of the surrounding beams in the interactive network.

[0025] In a further embodiment, based on the communication network at the upper layer of the interactive network component, a communication network may include multiple interactive networks, and the mobile terminal is placed in the communication network for management. When the mobile terminal accesses an interactive network in the communication network, the network control allocates control time slots to the interactive network of the beam where the terminal is currently located, as well as the interactive network of the beam adjacent to the beam. After the terminal beam is switched, the control burst can be sent directly after the forward alignment is completed. When the network control receives the control burst in the new beam, it updates the terminal information and reallocates the position of the control time slot. The network control records the terminal status information as follows:

[0026] In the field name "Terminal Address", the attribute is "rcst_mac", and the type is "Stirng";

[0027] In the field name "Interactive Network Identifier", the attribute is "in_id" and the type is "Int";

[0028] In the field name "Is the terminal currently in this interactive network", the attribute is "current" and the type is "Boolean";

[0029] In the field name "Business Slot Expiration Time", the attribute is "expiration_time" and the type is "Int".

[0030] The same satellite terminal may exist in multiple interactive networks. The interactive network the terminal is currently in can be determined by "current". The expiration time of the state can be determined by the priority of the terminal. When the terminal priority is high, the expiration time is long. When the terminal priority is low, the expiration time is short or does not support expiration. In this way, the system's time slot allocation can implement different strategies for users with different needs, and improve the overall utilization of network time slots while ensuring user services.

[0031] The step S3 is also included:

[0032] S3. The satellite terminal obtains service time slot resources in the interactive network of different beams and sets a timeout period for the service time slot resources. When the satellite terminal sends a control burst, the timeout period of the service time slot resources of the beam in the interactive network is reset. When it is detected that the satellite terminal has not sent a control burst after exceeding the set time, the service time slot resources in the interactive network of the beam are released. When it is detected that the satellite terminal sends a control burst within the set time, the service time slot resources in the interactive network of the beam are directly read and the service communication state is jumped into.

[0033] In a further embodiment, when a terminal applies for service time slot resources in an interactive network, the network control sets a timeout period for the resources of the terminal in the interactive network, and resets the timeout period of the service time slot resources of the terminal in the interactive network each time the network control receives a control burst from the terminal. If the terminal does not send a control burst in the interactive network within the timeout period, the network control releases the time slot resources of the terminal in the interactive network. The network control allocates service time slots to the terminal as follows:

[0034] In the field name "Interactive Network Identifier", the attribute is "in_id" and the type is "Int";

[0035] In field name "superframe sequence", attribute is "superframe_sequence", type is "Int";

[0036] In field name "superframe count", attribute is "superframe_count", type is "Int";

[0037] In the field name "frame number", the attribute is "frame_number" and the type is "Int";

[0038] In the field name "time slot number", the attribute is "time_slot_number" and the type is "Int";

[0039] In the field name "Terminal Address", the attribute is "rcst_mac" and the type is "String".

[0040] like Figure 1 As shown, in a further embodiment, the small station accesses the interactive network 5, obtains the control time slot resources of the interactive network 5 and the adjacent interactive networks 1, 2, 4, 6, 8, and 9, obtains the service time slot resources of the interactive network 5, and initiates service communication through the service time slot. At this time, the resources owned by the terminal are as follows:

[0041] Control time slot resources: IN1, IN2, IN4, IN5, IN6, IN8, IN9;

[0042] Business time slot resource: IN5.

[0043] IN stands for interactive network.

[0044] like Figure 2 As shown, in a further embodiment, when the small station moves to another interactive network 6, the forward channel is switched to the time division multiple access frequency of the interactive network 6. At this time, the dedicated control time slot of the small station in the interactive network 6 is directly obtained, and the state is directly changed from the "standby" state to the "reverse alignment" state, and then the service time slot application is directly sent through the dedicated control time slot. After the network control receives the control signaling sent by the satellite terminal 1 in the reverse channel of the interactive network 6, it adjusts the control time slot resources of the satellite terminal 1, switches its current interactive network to the interactive network 6, and allocates the control time slots of the surrounding beams to it, and then allocates the service time slot resources in the interactive network 6 to it, and then the satellite terminal can perform service communications in the interactive network 6. At this time, the satellite terminal 1 still has the service time slot resources in the interactive network 5. At this time, the resources owned by the terminal are as follows:

[0045] Control time slot resources: IN2, IN3, IN5, IN6, IN7, IN9, IN10;

[0046] Business time slot resources: IN5, IN6.

[0047] Afterwards, the small station continues to move within the beam range where the interactive network 6 is located. The network control detects that the state of the satellite terminal 1 in the interactive network 5 has timed out, and releases the service time slot resources of the terminal 1 in the interactive network 5.

[0048] like Figure 3As shown, in a further embodiment, the small station then comes to the boundary area of ​​beam 2, beam 5, and beam 6, and moves back and forth in this area. When the small station enters interactive network 2 for the first time, the network control allocates service time slot resources of interactive network 2 to it. At this time, the small station has service time slot resources in three interactive networks. When the small station switches back and forth between interactive network 2, interactive network 5, and interactive network 6, as long as the state timeout time in each interactive network is not exceeded, it will directly jump into the communication state after forward locking to avoid frequent interruption of user services. At this time, the resources owned by the terminal are as follows:

[0049] Control time slot resources: IN1, IN2, IN3, IN4, IN5, IN6, IN7, IN8, IN9, IN10;

[0050] Business time slot resources: IN2, IN5, IN6.

[0051] like Figure 4 As shown, a is the business communication process when the satellite terminal is turned on and accesses the network for the first time, b is the business communication process after the satellite terminal switches to the adjacent beam for the first time, and c is the business communication process after the satellite terminal switches to the adjacent beam multiple times.

[0052] It can be seen that the above embodiment reduces the login time of the terminal when switching the beam for the first time, as well as the repeated login and service time slot application during multiple switching, providing better protection for the services of mobile terminal users in the scenario of frequent network switching, effectively avoiding the problem of frequent interruption of user services, and also reducing the performance impact of concurrent operations caused by switching on network control services. By setting a timeout for service time slot resources, the time slot resources are automatically released or read according to the control emergency of the terminal, reducing the waste and conflict of time slot resources. At the same time, by utilizing the dynamic allocation of control time slots and service time slots, resources are flexibly adjusted according to the service needs and network conditions of the terminal, thereby improving the utilization rate of network resources and service quality.

[0053] According to one aspect of the present application, the following embodiment is provided. In step S1, according to the actual engineering scenario, the following steps are also included:

[0054] When each satellite terminal logs into the interactive network of the current beam, it predicts the adjacent beam it may switch to based on its own movement trajectory and speed, and sends a position prediction request to the NCC (Network Control Center, the same below).

[0055] According to the position prediction request sent by the satellite terminal, the NCC allocates control time slots in the current beam and adjacent beams, and returns the control time slot information to the terminal.

[0056] The satellite terminal predicts the number of service time slots it may need based on its own service characteristics and historical data, and sends a service time slot application to the NCC.

[0057] The NCC allocates service time slots in the current beam according to the service time slot application sent by the satellite terminal, and returns the service time slot information to the terminal.

[0058] The satellite terminal performs service communications through control time slots and service time slots, and at the same time re-predicts surrounding beams according to the positions of the switched beams and updates the control time slot information of the surrounding beams.

[0059] After switching to the adjacent beam, the satellite terminal uses the existing synchronization information for rapid alignment and the existing signaling information for signaling compression, directly reads the control time slot and service time slot in the adjacent beam, and continues service communications.

[0060] The satellite terminal obtains service time slot resources in the interactive network of different beams and sets a timeout period for the service time slot resources. When the terminal sends a control burst, the timeout period of the service time slot resources of the beam in the interactive network is reset. When it is detected that the terminal has not sent a control burst after the set time, the service time slot resources in the interactive network of the beam are released. When it is detected that the terminal sends a control burst within the set time, the service time slot resources in the interactive network of the beam are directly read and the service communication state is jumped into.

[0061] It should be noted that the above process can be implemented independently, and the following embodiments are given.

[0062] According to one aspect of the present application, the process of communicating by predicting the position of a satellite terminal comprises the following specific steps:

[0063] Step 1: When logging into the interactive network of the current beam, the satellite terminal predicts the adjacent beam it may switch to based on its own movement trajectory and speed.

[0064] For example, if the satellite terminal is moving at a constant speed in one direction, it can calculate the beam range that it may enter in the future based on its current position, speed and direction.

[0065] Step 2: The satellite terminal sends a position prediction request to the NCC, which contains its current position, speed, direction and predicted beam list.

[0066] Specifically, the following method can be used to obtain the current position:

[0067] Step 21: Obtain the orbital parameters of the satellite, including orbital altitude, eccentricity, inclination and argument of perigee. The above parameters can be obtained from the two-line orbital elements (TLE) or ephemeris of the satellite.

[0068] Step 22: Calculate the mean anomaly, eccentric anomaly and true anomaly of the satellite at any time. These angles can be obtained through Kepler's laws and geometric relationships.

[0069] Step 23: Convert the orbital coordinates of the satellite into Earth-centered fixed coordinates (ECF), which is achieved by using a rotation matrix or Euler angles.

[0070] Step 24: Calculate the ECF coordinates of the satellite terminal according to the latitude and longitude position and altitude of the ground satellite terminal, and then subtract them from the ECF coordinates of the satellite to obtain the relative position vector between the satellite and the satellite terminal. The relative velocity vector can be obtained by taking the derivative of the relative position vector or using the Doppler effect formula. If it is a synchronous communication satellite, the above process can be simplified.

[0071] In the calculation process, Doppler frequency shift needs to be considered. The specific processing process is as follows:

[0072] After obtaining the above orbital parameters of the satellite, the maximum visible elevation angle at the terminal is obtained; based on the orbital parameters of the satellite and the maximum visible elevation angle at the terminal, the elevation angle, azimuth angle and Doppler frequency shift curve of the satellite in the visible window are calculated using the spherical geometry relationship; based on the Doppler frequency shift curve of the satellite over time, the Doppler frequency shift value of the satellite at any time and the time when the Doppler frequency shift reaches the maximum and minimum values ​​are predicted.

[0073] Alternatively, a neural network model can be used for processing, as follows:

[0074] Collect Doppler shift data between the satellite and the satellite terminal as a training data set. This data can be obtained through actual measurement or simulation. Construct a deep neural network (DNN) model as a nonlinear regression fitter for Doppler shift. This model can be composed of multiple fully connected layers and activation functions; input the training data set into the DNN model, and use optimization methods such as back propagation algorithm and gradient descent method to adjust the weights and bias of the model so that the model can fit the training data set as much as possible. The satellite's orbital parameters and the terminal's location information are used as inputs and input into the trained DNN model to obtain the output Doppler shift prediction value.

[0075] Step 3: NCC allocates control slots in the current beam and predicted beam according to the position prediction request sent by the satellite terminal, and returns the control slot information to the terminal. The control slot information includes the control slot number, slot planning and modulation and demodulation mode of each beam.

[0076] Step 4: The satellite terminal saves the control time slot information in the current beam and the predicted beam according to the control time slot information returned by the NCC, and sends control signaling on the corresponding control time slot.

[0077] According to one aspect of the present application, the process of switching the communication process based on historical data specifically includes the following steps:

[0078] Step I: The satellite terminal predicts the number of service time slots it may need based on its own service characteristics and historical data.

[0079] For example, if the terminal is performing fixed-rate or predictable-rate services such as video calls or file transfers, the number of service time slots required can be calculated based on the service type, target rate, modulation and demodulation method, etc.

[0080] The method for predicting the service flow and the number of service time slots may be as follows:

[0081] Collect satellite communication service traffic data as a training data set. This data can be obtained from the monitoring platform or database of the satellite communication system.

[0082] Build a long short-term memory network (LSTM) model as a time series modeler for business traffic. This model can consist of one or more LSTM layers and a fully connected layer.

[0083] The training data set is divided into multiple subsequences according to a certain time step, and input into the LSTM model. The weights and biases of the model are adjusted using optimization methods such as the back propagation algorithm and the gradient descent method so that the model can fit the training data set as closely as possible.

[0084] The historical business traffic data is used as input and input into the trained LSTM model to obtain the output of the business traffic forecast value for a period of time in the future.

[0085] Of course, convolutional neural networks can also be used to implement this, as follows.

[0086] Collect satellite communication resource allocation data and user demand information as training data sets. These data can be obtained from the monitoring platform or database of the satellite communication system.

[0087] Construct a hybrid model of convolutional neural network (CNN) and attention mechanism as a spatial feature modeler and user importance weighter for resource allocation. This model can consist of one or more CNN layers, an attention layer, and a fully connected layer.

[0088] The training data set is divided into multiple sub-matrices according to a certain spatial dimension and input into the hybrid model of CNN and attention mechanism. The weights and biases of the model are adjusted using optimization methods such as back-propagation algorithm and gradient descent method so that the model can fit the training data set as closely as possible.

[0089] The historical resource allocation situation and user demand information are taken as input and input into the hybrid model of the trained CNN and attention mechanism to obtain the output of the business traffic forecast value and time slot allocation forecast value for a period of time in the future.

[0090] Step II: The satellite terminal sends a service time slot application to the NCC, which includes its own service type, target rate, modulation and demodulation mode, and the number of service time slots applied for.

[0091] Step III: NCC allocates service time slots in the current beam according to the service time slot application sent by the satellite terminal, and returns the service time slot information to the terminal. The service time slot information includes the number of each service time slot, time slot planning, modulation and demodulation mode, etc.

[0092] Step IV: The satellite terminal saves the service time slot information in the current beam according to the service time slot information returned by the NCC, and sends service data on the corresponding service time slot.

[0093] According to one aspect of the present application, a process of performing communication switching by a method of fast synchronization and signaling compression specifically includes the following steps:

[0094] After switching to an adjacent beam, the satellite terminal uses the existing synchronization information to quickly align.

[0095] For example, if the terminal already knows the frequency, symbol rate, coding method and other parameters of the forward signaling in the adjacent beam, the forward signaling can be directly locked without scanning or searching.

[0096] The satellite terminal uses the existing signaling information to perform signaling compression.

[0097] For example, if the terminal already knows some of the content contained in the forward signaling in the adjacent beam, such as the superframe structure, payload size, frame number and other fixed or derivable information, then this information can be removed or simplified from the forward signaling, thereby reducing the bandwidth and transmission time occupied by the forward signaling.

[0098] The satellite terminal directly reads the control time slots and service time slots allocated to it in the adjacent beams, and sends signaling or data on the corresponding time slots.

[0099] In a further embodiment, for multiple mobile satellite terminals, it can also be implemented in the following manner:

[0100] The location information, movement information and business information uploaded by each satellite terminal are read, and training and prediction are performed; the prediction results are then sent to each satellite terminal, and each satellite terminal switches to the predetermined network at the specified location or time.

[0101] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A terminal mobility management method based on multi-frequency time division multiple access MF-TDMA and the second generation digital video broadcast satellite return channel DVB-RCS2, characterized in that: The steps include: S1. Select a satellite terminal in the communication network, build an interactive network of multiple beams based on the communication network, and the satellite terminal logs in to the interactive network of the current beam to obtain the control time slots in the interactive network of the current beam and the interactive network of the adjacent beam; S2. The satellite terminal switches to an adjacent beam, logs in to the interactive network of the adjacent beam, and directly adopts the control time slot in the interactive network of the adjacent beam. The satellite terminal sends a service time slot application through the control time slot to obtain the service time slot. The satellite terminal initiates service communication through the service time slot, and at the same time re-obtains the control time slots of the surrounding beams in the interactive network according to the position of the switched beam.

2. The terminal mobility management method based on multi-frequency time division multiple access MF-TDMA and second-generation digital video broadcast satellite return channel DVB-RCS2 according to claim 1 is characterized in that: When the satellite terminal switches to an adjacent beam, the satellite terminal directly sends a control burst of the adjacent beam, updates the information of the satellite terminal according to the received control burst of the adjacent beam, and reallocates the control time slots of the surrounding beams in the interactive network.

3. The terminal mobility management method based on multi-frequency time division multiple access MF-TDMA and second-generation digital video broadcast satellite return channel DVB-RCS2 according to claim 2 is characterized in that: The step S3 is also included: S3. The satellite terminal obtains service time slot resources in the interactive network of different beams and sets a timeout period for the service time slot resources. When the satellite terminal sends a control burst, the timeout period of the service time slot resources in the interactive network is reset. When it is detected that the satellite terminal has not sent a control burst after exceeding the set time, the service time slot resources in the interactive network are released. When it is detected that the satellite terminal sends a control burst within the set time, the service time slot resources in the interactive network are directly read and the service communication state is jumped into.

4. The terminal mobility management method based on multi-frequency time division multiple access MF-TDMA and second-generation digital video broadcast satellite return channel DVB-RCS2 according to claim 1 is characterized in that: In step S1, when the satellite terminal logs into the interactive network of the current beam, it sends prediction data based on the location information to the network control center NCC, and the switching process is as follows: When logging into the interactive network of the current beam, the satellite terminal predicts the adjacent beam it may switch to based on its own movement trajectory and speed; the satellite terminal sends a position prediction request to the network control center NCC, which contains its current position, speed, direction and predicted beam list; The network control center NCC allocates control time slots in the current beam and the predicted beam according to the position prediction request sent by the satellite terminal, and returns the control time slot information to the terminal; the control time slot information includes the control time slot number, time slot planning and modulation and demodulation mode of each beam; The satellite terminal saves the control time slot information in the current beam and the predicted beam according to the control time slot information returned by the network control center NCC, and sends control signaling on the corresponding control time slot.

5. The terminal mobility management method based on multi-frequency time division multiple access MF-TDMA and second-generation digital video broadcast satellite return channel DVB-RCS2 according to claim 1 is characterized in that: In step S1, when the satellite terminal logs into the interactive network of the current beam, it sends the prediction data based on its own business to the network control center NCC, and the switching process is as follows: The satellite terminal predicts the number of service time slots it may need based on its own service characteristics and historical data; the satellite terminal sends a service time slot application to the network control center NCC, which includes its own service type, target rate, modulation and demodulation mode, and the number of service time slots applied for; The network control center NCC allocates service time slots in the current beam according to the service time slot application sent by the satellite terminal, and returns the service time slot information to the terminal. The service time slot information includes the number, time slot planning and modulation and demodulation mode of each service time slot; The satellite terminal saves the service time slot information in the current beam according to the service time slot information returned by the network control center NCC, and sends service data in the corresponding service time slot.

6. The terminal mobility management method based on multi-frequency time division multiple access MF-TDMA and the second generation digital video broadcast satellite return channel DVB-RCS2 according to claim 4 or 5, characterized in that: In step S1, when the satellite terminal logs into the interactive network of the current beam, it uses the method of fast synchronization and signaling compression to transmit data. The specific process is as follows: After switching to an adjacent beam, the satellite terminal uses the existing synchronization information for rapid alignment; the satellite terminal uses the existing signaling information for signaling compression; the satellite terminal directly reads the control time slots and service time slots that have been allocated to it in the adjacent beam, and sends signaling or data on the corresponding time slots.

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