Soft handover method and device suitable for telemetry system

Abstract

The invention discloses a soft handover method and device suitable for a telemetering system, and relates to the technical field of wireless communication, and the method comprises the following steps: monitoring GPS positioning in real time, and making a handover decision based on the GPS positioning; the aircraft is connected with a second telemetry ground station based on a switching judgment triggering state, a double-link maintaining state is formed, the first telemetry ground station and the second telemetry ground station receive the same data, and signals of the two telemetry ground stations are combined through a signal combining technology; when the aircraft enters the coverage area of the second telemetry ground station, the link between the aircraft and the first telemetry ground station is disconnected, the link between the aircraft and the second telemetry ground station is reserved, and switching is completed, the communication reliability during medium and long distance flight is remarkably improved, and the method is suitable for a high-reliability telemetry data transmission scene under the complex channel condition.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and specifically to a soft handover method and device applicable to a telemetry system. Background Art

[0002] With the rapid development of the aviation industry and the continuous improvement of the complexity of aircraft design, manufacturing, and testing, the key role of aviation telemetry technology in flight tests has become increasingly prominent. As an important bridge connecting aircraft and ground control centers in flight tests, the reliability of the telemetry system directly affects aircraft performance verification, safety monitoring, and data processing.

[0003] In a complex flight test environment, channel conditions are significantly affected by factors such as multipath effects, Doppler frequency shift, and time-varying characteristics, which pose higher requirements for communication quality. Although the traditional hard handover method is simple to implement, when the aircraft gradually leaves the coverage area of the ground station, the original link will be instantaneously disconnected and a new ground station will be connected, easily resulting in link interruption or signal quality degradation during the handover process. More seriously, data loss and transmission interruption may occur in the boundary area. The traditional hard handover method is difficult to meet the requirements in flight tests with high reliability and continuity requirements.

[0004] To solve the above problems, soft handover technology can be adopted. However, in the traditional soft handover process, although the signals of the mobile terminal can be received by multiple base stations simultaneously, these received signals are not further optimized in terms of signal quality through diversity combining techniques (such as maximum ratio combining). Specifically, the signals received by multiple base stations will be separately sent to the core network, and the base station controller will only select one path with the optimal signal quality for decoding, rather than enhancing the reception effect by combining the signals received by multiple base stations. Although this method can ensure the stability of the connection, it fails to fully utilize the redundant signal information received from multiple base stations, and thus may not be able to fully improve communication quality in high-interference or weak-signal situations. Summary of the Invention

[0005] To address the deficiencies mentioned in the above background art, the purpose of the present invention is to provide a soft handover method and device applicable to a telemetry system.

[0006] In a first aspect, the purpose of the present invention can be achieved through the following technical solution: A soft handover method applicable to a telemetry system, the method comprising the following steps:

[0007] Real-time monitor GPS positioning and make a handover decision based on the GPS positioning;

[0008] Based on the handover decision trigger state, connect the aircraft to a second telemetry ground station to form a dual-link holding state, wherein the first telemetry ground station and the second telemetry ground station receive the same data;

[0009] After the aircraft enters the coverage area of the second telemetry ground station, the link between the aircraft and the first telemetry ground station will be disconnected, and the link with the second telemetry ground station will be retained to complete the handover.

[0010] Combined with the first aspect, in some implementations of the first aspect, the method further includes: the determination conditions for the handover decision include any one or more of the following:

[0011] The aircraft performs real-time GPS positioning and starts the handover when it reaches the preset handover range between the two stations;

[0012] The diversity gain between the first telemetry ground station and the second telemetry ground station is lower than the preset threshold.

[0013] Combined with the first aspect, in some implementations of the first aspect, the method further includes: the determination process of the preset handover range between the two stations:

[0014] It is determined based on the midpoint of the geographical locations of the first telemetry ground station and the second telemetry ground station. Specifically, the handover range is determined by calculating the geographical distance between the two stations and taking the area near the midpoint as the handover area. When the aircraft reaches this handover area through GPS positioning, the system determines that it has entered the handover range and starts the handover process.

[0015] Combined with the first aspect, in some implementations of the first aspect, the method further includes: the acquisition process of the preset threshold:

[0016] The calculation process of the preset threshold is as follows:

[0017] The system measures the signal-to-noise ratios of the first telemetry ground station and the second telemetry ground station in real time, denoted as SNR 1 and SNR 2 , calculates the signal-to-noise ratio difference ΔSNR between the two ground stations, and the formula is:

[0018] ΔSNR = |SNR 1 - SNR 2 |

[0019] According to the characteristics of the signal combining technology, the threshold value of the signal-to-noise ratio difference is set as ΔSNR threshold , when ΔSNR > ΔSNR threshold , the system determines that the diversity gain has fallen below the effective range and ends the handover state.

[0020] In combination with the first aspect, in certain implementations of the first aspect, the method further includes: in the handover process, through the dual-link maintenance technology, the aircraft simultaneously establishes communication connections with the first telemetry ground station and the second telemetry ground station; meanwhile, the RAN component coordinates the antenna directions and transmission powers of the two telemetry ground stations to optimize the connections; and performs weighted processing on the telemetry data received by the two telemetry ground stations through the signal diversity combining technology, where the signal diversity combining technology is the soft bit combining technology or other combining technologies.

[0021] In combination with the first aspect, in certain implementations of the first aspect, the method further includes: the process of performing weighted processing on the telemetry data received by the two telemetry ground stations through the signal diversity combining technology includes:

[0022] First, use the signal-to-noise ratio estimation method to obtain the signal-to-noise ratios SNR 1 、SNR 2 of the two telemetry ground stations, calculate the combining weights according to the magnitudes of the signal-to-noise ratios, specifically as follows

[0023]

[0024] In the formula, w i represents the weight of the i-th telemetry ground station, SNR i is the signal-to-noise ratio of the i-th path. According to the calculated weighting coefficients, perform weighted summation on the log-likelihood ratio values of all signal reception paths to obtain the finally combined log-likelihood ratio value LLR combined , specifically as follows:

[0025]

[0026] In the formula, LLR i (b) represents the LLR value of the b-th bit of the i-th path, and LLR combined (b) represents the LLR value of the b-th bit after combination.

[0027] In a second aspect, to achieve the above object, the present invention discloses a soft handover device applicable to a telemetry system, including:

[0028] A handover decision module for real-time monitoring of GPS positioning and making a handover decision based on the GPS positioning;

[0029] A dual-link connection module for connecting the aircraft to the second telemetry ground station based on the triggered state of the handover decision to form a dual-link maintenance state, where the first telemetry ground station and the second telemetry ground station receive the same data;

[0030] The soft handover module is used to disconnect the link between the aircraft and the first telemetry ground station and retain the link with the second telemetry ground station after the aircraft enters the coverage area of the second telemetry ground station, so as to complete the handover.

[0031] In another aspect of the present invention, in order to achieve the above object, a terminal device is disclosed, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. The computer program capable of running on the processor is stored in the memory. When the processor loads and executes the computer program, a soft handover method applicable to a telemetry system as described above is adopted.

[0032] In yet another aspect of the present invention, in order to achieve the above object, a computer-readable storage medium is disclosed. A computer program is stored in the computer-readable storage medium. When the computer program is loaded and executed by a processor, a soft handover method applicable to a telemetry system as described above is adopted.

[0033] Advantages of the present invention:

[0034] The present invention can improve the communication stability and data transmission reliability during the handover process of an aviation telemetry system: By introducing the soft handover technology, the problems of instantaneous link break and data loss in traditional hard handover are avoided, ensuring smooth communication transition of the aircraft within the coverage areas of multiple telemetry ground stations. At the same time, combined with the diversity signal combining technology, the anti-interference ability and bit error rate performance of the received signal are effectively improved. The present invention can adapt to complex channel environments, meet the requirements of high reliability and real-time performance, and provide a more efficient and stable communication solution for modern flight tests. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts;

[0036] Figure 1 It is a schematic flowchart of the method of the present invention;

[0037] Figure 2 It is a schematic diagram of the telemetry soft handover scenario of the present invention;

[0038] Figure 3 It is a schematic diagram of the device structure of the present invention. Detailed Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Embodiment 1:

[0041] Next, relevant terms related to the embodiments of the present application will be introduced:

[0042] A telemetry system is a system that has the functions of measuring, transmitting, and processing certain parameters of a measured object at a certain distance, that is, a system that transmits the measured values of the object parameters at a short distance to a measurement station at a long distance to achieve long-distance measurement. A telemetry system generally consists of three major parts: an input device, a data transmission device, and a terminal device. Among them, the data transmission device includes devices for multiplexing, transmitting, receiving, and demultiplexing multiple signals coming from the input device. The working principle of the telemetry system involves aspects such as information acquisition, information transmission, and information processing. The telemetry system is essentially a type of multi-channel data transmission system. In order to complete the transmission of multiple-channel information with one channel, multiplexing technology can be used.

[0043] As Figure 1 shown, a soft handover method applicable to a telemetry system includes the following steps:

[0044] S101: Real-time monitor GPS positioning and make a handover decision based on the GPS positioning;

[0045] The determination conditions for the handover decision include any one or more of the following:

[0046] The aircraft performs real-time GPS positioning and starts to hand over when it reaches the preset handover range between two stations;

[0047] The diversity gain between the first telemetry ground station and the second telemetry ground station is lower than a preset threshold.

[0048] The preset handover range between two stations:

[0049] Determination of the handover range: The preset handover range between two stations is determined based on the midpoint of the geographical locations of the first telemetry ground station and the second telemetry ground station. Specifically, the handover range is determined by calculating the geographical distance between the two stations and taking the area near the midpoint as the handover area. When the aircraft reaches this handover area through GPS positioning, the system determines that it enters the handover range and starts the handover process.

[0050] The acquisition process of the preset threshold:

[0051] The preset threshold refers to the threshold of the signal-to-noise ratio (SNR) difference between the first telemetry ground station and the second telemetry ground station. When the SNR difference between the two ground stations exceeds this threshold, the system determines that the diversity gain is no longer sufficient to effectively improve the communication quality, ends the dual-link maintenance state, disconnects from the first telemetry ground station, and only retains the communication link with the second telemetry ground station. Specifically, when the SNR difference between the two ground stations exceeds a certain threshold (e.g., 10 dB), the gain of the signal combining technology will become negligible, and it is no longer practical to continue maintaining the dual-link state at this time.

[0052] The calculation process of the threshold is as follows:

[0053] The system measures the SNR of the first telemetry ground station and the second telemetry ground station in real time, denoted as SNR 1 and SNR 2 . Calculate the SNR difference ΔSNR between the two ground stations. The formula is:

[0054] ΔSNR = |SNR 1 - SNR 2 |

[0055] According to the characteristics of the signal combining technology, set the threshold value of the SNR difference as ΔSNR threshold , and the threshold value can be determined according to the actual situation. When ΔSNR > ΔSNR threshold , the system determines that the diversity gain has fallen below the effective range and ends the handover state.

[0056] S102: Based on the handover decision trigger state, connect the aircraft to the second telemetry ground station to form a dual-link maintenance state, where the first telemetry ground station and the second telemetry ground station receive the same data;

[0057] In the handover process, through the dual-link maintenance technology, the aircraft establishes communication connections with both the first telemetry ground station and the second telemetry ground station at the same time; at the same time, the RAN component coordinates the antenna directions and transmission powers of the two telemetry ground stations to optimize the connection; the telemetry data received by the two telemetry ground stations is weighted through the signal diversity combining technology, where the signal diversity combining technology is soft bit combining technology or other combining technologies.

[0058] The process of weighting the telemetry data received by the two telemetry ground stations through the signal diversity combining technology includes:

[0059] First, use the SNR estimation method to obtain the SNR of the two telemetry ground stations SNR 1 , SNR 2 , and calculate the combining weights according to the SNR magnitudes as follows

[0060]

[0061] In the formula, w i represents the weight of the i-th telemetry ground station, and SNR i is the weighting coefficient calculated according to the signal-to-noise ratio of the i-th path. The logarithmic likelihood ratio values of all signal reception paths are weighted and summed to obtain the finally combined logarithmic likelihood ratio value LLR combined , specifically as follows:

[0062]

[0063] In the formula, LLR i (b) represents the LLR value of the b-th bit of the i-th path, and LLR combined (b) represents the LLR value of the b-th bit after combination.

[0064] S103: After the aircraft enters the coverage area of the second telemetry ground station, the link between the aircraft and the first telemetry ground station will be disconnected, and the link with the second telemetry ground station will be retained to complete the handover.

[0065] Specifically, the solution of the present invention will be further described by the following embodiments:

[0066] The present invention is applicable to the scenario where a test aircraft crosses the coverage areas of multiple telemetry ground stations during flight. The telemetry system realizes data transmission and link management through a radio access network (RAN). The test aircraft transmits flight status data in real time, and the telemetry ground station is responsible for receiving, processing, and forwarding these data. To ensure the continuity of communication during the handover process, the present invention designs the following soft handover steps.

[0067] As Figure 2 shown, at Time 0, the aircraft is within the communication range of telemetry ground station 1 and transmits data to ground station 1 through a stable link. The aircraft obtains its own positioning in real time through GPS. When the aircraft gradually moves away from ground station 1, the link quality may deteriorate. At this time, if the aircraft enters the handover area preset by the two ground stations, the system starts the handover process;

[0068] At Time 1, the aircraft gradually enters the communication range of Ground Station 2 and starts to establish a communication connection with Ground Station 2. At this time, the aircraft maintains a dual-link connection state with both Ground Station 1 and Ground Station 2 (indicated by the two dashed blue arrows in the figure). During the dual-link maintenance phase, the two ground stations receive the same telemetry data and process the received signals through diversity techniques (such as signal combining or selection combining), thereby improving the reliability and anti-interference ability of the received signals. To further optimize the communication quality, the Radio Access Network (RAN) components coordinate the antenna directions and transmission powers of Ground Station 1 and Ground Station 2, dynamically adjust the link parameters, and ensure that the signal strengths and qualities of the two communication links reach the optimal level. The dual-link maintenance mechanism in this phase avoids the risks of data loss and link interruption during the handover instant;

[0069] At Time 2, the aircraft fully enters the coverage range of Ground Station 2. The system disconnects the connection with Ground Station 1 based on the link quality parameters and only retains the communication link with Ground Station 2 (indicated by the solid blue arrow in the figure). After the handover is completed, all telemetry data is transmitted to the flight test command hall through Ground Station 2. To ensure the communication stability after the handover, the flight test command hall is also responsible for continuously monitoring the link state of Ground Station 2 and optimizing the link performance through dynamic resource allocation;

[0070] Embodiment 2: Second aspect, as Figure 3 shown, to achieve the above object, the present invention discloses a soft handover device applicable to a telemetry system, including:

[0071] A handover decision module, configured to monitor the GPS positioning in real time and make a handover decision based on the GPS positioning;

[0072] A dual-link connection module, configured to connect the aircraft with the second telemetry ground station based on the triggered state of the handover decision to form a dual-link maintenance state, wherein the first telemetry ground station and the second telemetry ground station receive the same data;

[0073] A soft handover module, configured to disconnect the link between the aircraft and the first telemetry ground station and retain the link with the second telemetry ground station to complete the handover when the aircraft enters the coverage range of the second telemetry ground station.

[0074] Based on the same inventive concept, the present invention further provides a computer device, which includes: one or more processors, and a memory for storing one or more computer programs; the program includes program instructions, and the processor is configured to execute the program instructions stored in the memory. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is used to implement one or more instructions. Specifically, it is used to load and execute one or more instructions in the computer storage medium to implement the above method.

[0075] It should be further noted that, based on the same inventive concept, the present invention further provides a computer storage medium, on which a computer program is stored, and the computer program, when run by a processor, executes the above method. The storage medium may be any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may, for example, but is not limited to, an electrical, magnetic, optical, electrical, magnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the computer-readable storage medium include: an electrical connection having one or more wires, a portable computer disk, a hard disk, a Random Access Memory (RAM), a Read-Only Memory (ROM), an Erasable Programmable Read-Only Memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, the computer-readable storage medium may be any tangible medium that contains or stores a program, and the program may be used by or combined with an instruction execution system, apparatus, or device.

[0076] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0077] The foregoing has shown and described the basic principles, main features and advantages of the present disclosure. Those skilled in the art should understand that the present disclosure is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present disclosure. Without departing from the spirit and scope of the present disclosure, the present disclosure will have various changes and improvements, and these changes and improvements fall within the scope of the present disclosure claimed.

Claims

1. A soft switching method applicable to a telemetry system, characterized in that: The method comprises the following steps: Monitor GPS positioning in real time and make switching decisions based on GPS positioning; Based on the switching decision trigger state, the aircraft is connected to the second telemetry ground station to form a dual link holding state, wherein the first telemetry ground station and the second telemetry ground station receive the same data, and the signals received by the two telemetry ground stations are combined by a signal combining technology; When the aircraft enters the coverage area of ​​the second telemetry ground station, the link between the aircraft and the first telemetry ground station will be disconnected, and the link with the second telemetry ground station will be retained, completing the switch.

2. A soft switching method applicable to a telemetry system according to claim 1, characterized in that: The switching decision condition includes any one or more of the following: The aircraft performs real-time GPS positioning and starts switching when it reaches the preset switching range between the two stations; The diversity gain between the first telemetry ground station and the second telemetry ground station is lower than a preset threshold.

3. A soft switching method applicable to a telemetry system according to claim 2, characterized in that: The preset switching range determination process between two stations: The switching range is determined based on the midpoint of the geographical locations of the first telemetry ground station and the second telemetry ground station. The switching range is calculated by calculating the geographical distance between the two stations and taking the area near the midpoint as the switching area. When the aircraft reaches the switching area through GPS positioning, the system determines that it has entered the switching range and starts the switching process.

4. A soft switching method applicable to a telemetry system according to claim 3, characterized in that: The process of obtaining the preset threshold: The calculation process of the preset threshold is as follows: The system measures the signal-to-noise ratio of the first telemetry ground station and the second telemetry ground station in real time, which are recorded as SNR1 and SNR2 respectively, and calculates the difference in signal-to-noise ratio between the two ground stations, ΔSNR, using the formula: ΔSNR=|SNR1-SNR2| Set the signal-to-noise ratio difference threshold to ΔSNR threshold , when ΔSNR>ΔSNR threshold , the system determines that the diversity gain is lower than the effective range and ends the switching state.

5. A soft switching method applicable to a telemetry system according to claim 1, characterized in that: During the switching process, the aircraft establishes communication connections with the first telemetry ground station and the second telemetry ground station simultaneously through dual-link maintenance technology; at the same time, the RAN component coordinates the antenna direction and transmission power of the two telemetry ground stations to optimize the connection; the telemetry data received by the two telemetry ground stations are weightedly processed through signal diversity combining technology, wherein the signal diversity combining technology is soft bit combining technology or other combining technology.

6. A soft switching method applicable to a telemetry system according to claim 5, characterized in that: The process of weighted processing of telemetry data received by two telemetry ground stations by using signal diversity combining technology includes: First, the signal-to-noise ratio estimation method is used to obtain the signal-to-noise ratios SNR1 and SNR2 of the two telemetry ground stations. The merging weight is calculated according to the signal-to-noise ratio as follows: Where w i represents the weight of the i-th telemetry ground station, SNR i The signal-to-noise ratio of the i-th path is calculated based on the weighted coefficient, and the log-likelihood ratio values ​​of all signal receiving paths are weighted and summed to obtain the final combined log-likelihood ratio value LLR combined ,as follows: Where LLR i (b) represents the LLR value of the bth bit of the ith path, LLR combined (b) represents the LLR value of the b-th bit after merging.

7. A soft switching device suitable for a telemetry system, characterized in that: include: A switching decision module is used to monitor GPS positioning in real time and make switching decisions based on GPS positioning; A dual-link connection module, used to connect the aircraft to a second telemetry ground station based on a switching decision trigger state to form a dual-link holding state, wherein the first telemetry ground station and the second telemetry ground station receive the same data; The soft switching module is used to disconnect the link between the aircraft and the first telemetry ground station and retain the link with the second telemetry ground station to complete the switching when the aircraft enters the coverage area of ​​the second telemetry ground station.

8. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that: The memory stores a computer program that can be run on the processor. When the processor loads and executes the computer program, a soft switching method applicable to a telemetry system according to any one of claims 1 to 6 is adopted.

9. A computer-readable storage medium having a computer program stored therein, characterized in that: When the computer program is loaded and executed by the processor, a soft switching method applicable to a telemetry system according to any one of claims 1 to 6 is adopted.

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