Reverse time bias compensation method, device, equipment and medium

Abstract

The invention provides a reverse time offset compensation method, device and equipment and a medium, and the method comprises the steps: determining a superframe header position through employing a superframe synchronization algorithm when a digital video broadcasting DVB terminal searches a satellite; performing frame format analysis processing based on the superframe header position to obtain a corresponding frame type format; when the superframe header position is in an available state, obtaining a theoretical frame header position corresponding to the frame type format according to the frame type format; and according to the theoretical frame header position and the superframe header position, determining a time offset error value and sending the time offset error value to a signaling processing unit, so that the signaling processing unit performs time offset compensation correction according to the time offset error value and determines a target time offset value. According to the scheme, the access stability and the data transmission reliability of the DVB communication system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite communication, in particular to a reverse timing offset compensation method, device, equipment and medium. BACKGROUND

[0002] In a digital video broadcast (DVB) communication system, the bidirectional transmission of data relies on an accurate timing synchronization mechanism, and the stability of reverse data transmission directly affects the overall communication quality. During the reverse data transmission process, the terminal adjusts the transmission time according to the reverse scheduling descriptor under the base station to ensure that the signal can accurately reach the base station and be correctly received, and the calculation accuracy directly determines whether the reverse data can accurately fall into the preset receiving time slot of the base station. When the terminal transmits data in reverse, the transmission timing needs to be adjusted according to the timing advance (TA) calculation result to ensure that the signal accurately reaches the receiving window of the base station; if there is a large error in TA calculation, the reverse data will deviate from the intended time slot position, causing the base station to fail to demodulate, and thus causing data transmission failure.

[0003] At present, the correction logic in the related art can only be triggered when the terminal enters the fine synchronization stage and the base station has successfully demodulated the terminal signal. At this time, the base station will issue a correction information descriptor to guide the terminal to correct the TA error. This means that in the scenario where the base station fails to demodulate, the terminal cannot obtain any correction feedback of the TA error. During the terminal access process, due to factors such as unstable initial synchronization and channel environment interference, the TA error is more likely to be at a large level, and at this time, if there is no effective correction method, the probability of base station demodulation failure will increase significantly, directly causing the terminal access failure. This cycle of "demodulation success to correct error, and large error leading to demodulation failure" affects the access stability and data transmission reliability of the DVB communication system. SUMMARY

[0004] The present application provides a reverse timing offset compensation method, device, equipment and medium.

[0005] The first aspect of the embodiment of the present application provides a reverse timing offset compensation method, which comprises:

[0006] When a digital video broadcast (DVB) terminal searches for a satellite, a superframe synchronization algorithm is used to determine the position of a superframe header;

[0007] Based on the position of the superframe header, frame format analysis processing is performed to obtain a corresponding frame type format;

[0008] When the position of the superframe header is in a usable state, the frame type format is used to obtain a theoretical frame header position corresponding to the frame type format.

[0009] According to the theoretical frame header position and the superframe header position, a time offset error value is determined and sent to a signaling processing unit, so that the signaling processing unit performs time offset compensation correction according to the time offset error value to determine a target time offset value.

[0010] A second aspect of the embodiment of the present application provides a reverse time offset compensation device, comprising:

[0011] A determining module is configured to determine a superframe header position by using a superframe synchronization algorithm when a digital video broadcast (DVB) terminal searches for a satellite.

[0012] An analyzing module is configured to perform frame format analysis processing based on the superframe header position to obtain a corresponding frame type format.

[0013] An obtaining module is configured to obtain a theoretical frame header position corresponding to the frame type format according to the frame type format when the superframe header position is in an available state.

[0014] A compensating module is configured to determine a time offset error value according to the theoretical frame header position and the superframe header position and send the time offset error value to a signaling processing unit, so that the signaling processing unit performs time offset compensation correction according to the time offset error value to determine a target time offset value.

[0015] A third aspect of the embodiment of the present application provides a communication terminal device, comprising a memory and a processor, the memory stores a computer program, and the processor implements the steps of any one of the above methods when executing the computer program.

[0016] A fourth aspect of the embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of any one of the above methods.

[0017] The embodiment of the present application provides a reverse time offset compensation method, which comprises the following steps: when a digital video broadcast (DVB) terminal searches a satellite, a superframe header position is determined by using a superframe synchronization algorithm; frame format analysis processing is performed based on the reverse time offset compensation superframe header position, so that a corresponding frame type format is obtained; when the reverse time offset compensation superframe header position is in an available state, a theoretical frame header position corresponding to the reverse time offset compensation frame type format is obtained according to the reverse time offset compensation frame type format; and a time offset error value is determined according to the reverse time offset compensation theoretical frame header position and the reverse time offset compensation superframe header position, and is sent to a signaling processing unit, so that the reverse time offset compensation signaling processing unit performs time offset compensation correction according to the reverse time offset compensation time offset error value, and determines a target time offset value. Compared with the prior art, the technical scheme in the present application does not need to rely on base station demodulation of a reverse signal, breaks the restriction that correction can be started only when the base station demodulates the reverse signal in the related art, so that the terminal can obtain frame header position basic data in an access stage, provides a precondition for TA error correction, and avoids a passive state without correction feedback; the frame type format is analyzed based on the superframe header position, the corresponding theoretical frame header position is obtained, the protocolized frame structure of the forward signal is used, the time offset error is directly derived from the forward link by comparing the theoretical frame header position with the actual frame header position, the demodulation result of the reverse link is not needed, and the problem of "no error reference source" when the reverse link demodulation fails is solved; and when the superframe header position is in the available state, the time offset error value is determined according to the theoretical frame header position and the superframe header position, and is sent to the signaling processing unit for correction, so that in the scene that the TA error is large in the terminal access stage, the time offset error is actively calculated and compensated, the cycle that "demodulation success can correct error, and the error is too large to cause demodulation failure" is broken, the base station demodulation failure probability is effectively reduced, and the access stability and data transmission reliability of the DVB communication system are improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are included to provide a further understanding of the present application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and serve to explain the present application. In the drawings:

[0019] Figure 1 A structural schematic diagram of a communication terminal device is provided for an embodiment of the present application;

[0020] Figure 2 A flowchart of a reverse time offset compensation method is provided for an embodiment of the present application;

[0021] Figure 3 A flowchart of a method for determining a frame type format according to a superframe header position is provided for an embodiment of the present application;

[0022] Figure 4 A method flowchart of reverse time offset compensation is provided for another embodiment of the present application;

[0023] Figure 5 The structure diagram of the reverse time offset compensation device provided by an embodiment of the application is shown. DETAILED DESCRIPTION

[0024] In the implementation of the application, the inventor finds that in the traditional reverse time offset compensation scheme, the error can be corrected only when the demodulation is successful, and the demodulation fails due to the too large error, which affects the access stability and data transmission reliability of the DVB communication system.

[0025] In order to make the technical solutions and advantages of the embodiments of the application clearer, the exemplary embodiments of the application are further described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. It should be noted that the embodiments and features in the embodiments can be combined with each other without conflict.

[0026] Based on the above defects, the application provides a reverse time offset compensation method. Compared with the related art, the technical solution in the application does not need to rely on the base station to demodulate the reverse signal, breaks the limitation in the related art that "the base station demodulates the reverse signal to start correction", so that the terminal can obtain the frame header position basic data in the access stage, provides a precondition for TA error correction, and avoids the passive state of no correction feedback. Based on the super frame header position, the frame type format is parsed and the corresponding theoretical frame header position is obtained. With the protocolized frame structure of the forward signal, the time offset error is directly derived from the forward link by comparing the theoretical frame header position with the actual frame header position, without relying on the demodulation result of the reverse link, which solves the problem of "no error reference source" when the reverse link demodulation fails. When the super frame header position is in the available state, the time offset error value is determined according to the theoretical frame header position and the super frame header position and sent to the signaling processing unit for correction. In the scene where the TA error is large in the terminal access stage, the time offset error is actively calculated and compensated, which breaks the cycle of "demodulation success to correct error, and too large error leads to demodulation failure", effectively reduces the probability of base station demodulation failure, and improves the access stability and data transmission reliability of the DVB communication system.

[0027] The scheme in the embodiments of the application can be implemented in various computer languages, such as the object-oriented program design language Java and the interpreted script language JavaScript.

[0028] Please refer to Figure 1 The structure diagram of a communication terminal device provided by an embodiment of the application is shown. As shown in Figure 1As shown, the communication terminal device includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. The processor of the communication terminal device is configured to provide computing and control capabilities. The memory of the communication terminal device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium can be a magnetic disk, for example. The non-volatile storage medium stores files (which can be files to be processed or processed files), an operating system and a computer program, etc. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium to run. The network interface of the communication terminal device is configured to communicate with external terminals through network connection. The computer program is executed by the processor to implement a reverse time offset compensation method. The display screen of the communication terminal device can be a liquid crystal display screen or an electronic ink display screen. The input device of the communication terminal device can be a touch layer overlaid on the display screen, or a key, trackball or touchpad provided on the shell of the communication terminal device, or an external keyboard, touchpad or mouse, etc. The communication terminal device has wireless communication and transceiving functions, and can include a self-organizing network communication device, a data link communication device and a Bluetooth communication device, etc.

[0029] Please refer to Figure 2 The following embodiments take the above communication terminal device as an execution subject, and take the reverse time offset compensation method provided by the embodiments of the present application as an example to perform data processing. The reverse time offset compensation method provided by the embodiments of the present application includes the following steps 201-204:

[0030] Step 201, when a digital video broadcast (DVB) terminal searches for a satellite, a superframe synchronization algorithm is used to determine the position of a superframe header.

[0031] It should be noted that when the digital video broadcast (DVB) terminal searches for a satellite or accesses, it will constantly search for digital video broadcast (DVB) forward signals from the satellite or the base station, and obtain received data. Whether or not the DVB forward signal is searched for, the superframe synchronization algorithm will be started to determine the position of the superframe header.

[0032] The superframe refers to a data unit composed of multiple frames, and is used to implement complex timing management, such as coordinated transmission of multiple frames, synchronization calibration, etc. The superframe header is the starting identifier of the superframe, and includes superframe number, frame structure type, synchronization code and other key information.

[0033] Specifically, the superframe synchronization algorithm described above works based on the data correlation matching principle. The terminal will intercept a piece of data from the received data and compare it bit by bit with the local pre-stored superframe header template data conforming to the DVB protocol. The correlation value of the two pieces of data can be calculated by multiplying the bits and then accumulating the sum. Subsequently, the algorithm will traverse the entire received data segment in the form of a sliding window, repeating the above correlation calculation, and finally determining the position with the maximum correlation value as the superframe header position.

[0034] The superframe synchronization algorithm adopted in this embodiment can accurately determine the superframe header position of the received data and provide good data guidance information for subsequent time offset compensation processing.

[0035] Step 202, performing frame format analysis processing based on the superframe header position to obtain the corresponding frame type format.

[0036] Specifically, in the DVB communication system, the frame format analysis processing based on the superframe header position is essentially to locate and read the key control information in the superframe by means of the "starting anchor point" function of the superframe header, so as to determine the data organization structure of the current superframe. The superframe header itself contains the core description information of the superframe, such as the frame structure identification field and format type coding defined by the protocol.

[0037] After the terminal locks the superframe header position by the superframe synchronization algorithm, it will take this position as the starting point and decode the bit stream of the corresponding length according to the offset rule defined by the DVB protocol. For example, if the superframe header position is at the 1000th bit of the data stream, the subsequent 10-20 bits are the frame type identification according to the protocol, then the terminal will read the data from the 1010th-1020th bit, and identify the coding of this field, such as "0010" corresponding to the frame format of QPSK modulation and "0110" corresponding to the frame format of 16QAM modulation, to obtain the final corresponding frame type format.

[0038] Step 203, when the superframe header position is in the available state, obtaining the theoretical frame header position corresponding to the frame type format according to the frame type format.

[0039] Step 204, determining the time offset error value according to the theoretical frame header position and the superframe header position and sending it to the signaling processing unit, so that the signaling processing unit performs time offset compensation correction according to the time offset error value to determine the target time offset value.

[0040] After determining the superframe header position, it can be judged whether it is in the available state based on the superframe header position. When the superframe header position is in the available state, it means that the position has been verified by bit-level decoding and is the real superframe header coordinate matched with the actual signal. At this time, the communication terminal will call the theoretical frame header position corresponding to the frame type format from the DVB protocol based on the frame type format parsed in the previous step. The theoretical frame header position is the "standard anchor point" preset by the protocol for each frame type. For example, the theoretical frame header of a certain type of frame format used for high-speed data transmission is specified at the 200th bit after the start of the superframe, and the theoretical frame header of another type of frame format used for low-latency transmission corresponds to the 300th bit. The mapping relationship between the above-mentioned frame type format and the theoretical frame header position can be predefined by the protocol to ensure that the terminal can accurately obtain the standard timing reference matched with the current signal.

[0041] After determining the theoretical frame header position, the timing offset error value is determined in combination with the theoretical frame header position and the actual superframe header position. Since the transmission rate of the DVB signal is fixed, it can be converted into a time offset by a unit bit transmission time, that is, the timing offset error value is obtained, and then the timing offset error value is sent to the signaling processing unit. After the timing offset error value is sent to the signaling processing unit, it will be used to correct the original TA (timing offset) estimation value: the signaling processing unit combines the original TA estimation value with the timing offset error value to calculate a target timing offset value that is more consistent with the actual transmission timing.

[0042] It can be understood that the above-mentioned signaling processing unit can be a Layer 1 Control (L1C) unit in the DVB system, which is a signaling module responsible for control logic and undertakes core control functions such as timing offset (TA) calculation, distance calculation, and synchronization calibration. It is a key command signal for timing coordination between the terminal and the base station and data transmission scheduling.

[0043] The timing offset correction compensation scheme in this step avoids the limitation that correction information can only be obtained by demodulating the reverse signal of the base station. Even if the reverse link is not stable, the terminal can actively calibrate the transmission time through the timing offset of the forward signal to ensure that the reverse data is sent according to the target timing offset value and accurately falls into the base station receiving time slot, thereby reducing the demodulation failure probability caused by timing offset error from the root.

[0044] The embodiment of the application provides a reverse time offset compensation method, which comprises the following steps: when a digital video broadcast (DVB) signal is searched, a superframe header position is determined by using a superframe synchronization algorithm; frame format analysis processing is performed based on the reverse time offset compensation superframe header position, so that a corresponding frame type format is obtained; when the reverse time offset compensation superframe header position is in a usable state, a theoretical frame header position corresponding to the reverse time offset compensation frame type format is obtained according to the reverse time offset compensation frame type format; a time offset error value is determined according to the reverse time offset compensation theoretical frame header position and the reverse time offset compensation superframe header position, and is sent to a signaling processing unit, so that the reverse time offset compensation signaling processing unit performs time offset compensation correction according to the reverse time offset compensation time offset error value, and determines a target time offset value. Compared with the prior art, the technical scheme in the application does not need to rely on base station demodulation of a reverse signal, breaks the limitation that the related art is that "the base station demodulation of the reverse signal can start correction", so that the terminal can obtain frame header position basic data in an access stage, provides a precondition for TA error correction, and avoids a passive state without correction feedback; the frame type format is analyzed based on the superframe header position, the corresponding theoretical frame header position is obtained, the protocolized frame structure of the forward signal is used, the time offset error is directly derived from the forward link by comparing the theoretical frame header position with the actual frame header position, the demodulation result of the reverse link is not needed, and the problem of "no error reference source" when the demodulation of the reverse link fails is solved; and when the superframe header position is in the usable state, the time offset error value is determined according to the theoretical frame header position and the superframe header position, and is sent to the signaling processing unit for correction, so that in the scene that the TA error is large in the terminal access stage, the time offset error is actively calculated and compensated, the cycle that "the demodulation is successful to correct the error, and the error is too large to cause demodulation failure" is broken, the base station demodulation failure probability is effectively reduced, and the access stability and data transmission reliability of the DVB communication system are improved.

[0045] In an optional embodiment of the application, the specific implementation manner of determining the superframe header position by using the superframe synchronization algorithm comprises the following steps:

[0046] The plurality of segmented data are determined from the received data; all the received data are traversed, each segmented data is multiplied by bit by bit with the frame header template data specified by the protocol and is summed to obtain a processing result; and the position corresponding to the segmented data with the largest processing result is taken as the superframe header position.

[0047] It should be noted that the superframe synchronization algorithm is essentially based on data correlation matching, and the received data is compared with reference data known locally, for example, the frame header template specified by the data protocol

[0048] Specifically, after the received data is acquired, a processing result is obtained by multiplying and accumulating a segment of the received data at each time according to the data length of the reference data, the processing result being used to represent the correlation between the segment of data and the frame header template data. The correlation values between each position of all received data and the frame header template data are calculated, the segment of data with the maximum correlation value being determined, which represents the highest matching degree between the segment of data and the frame header template data, and then the position corresponding to the segment of data with the maximum correlation value is taken as the super frame header position.

[0049] For example, the frame header template data is [1, 0, 1, 0] and a segment of data in the received data is [1, 0, 1, 0], then the bit-by-bit multiplication and summation is 1*1+0*0+1*1+0*0=2; if another segment of data in the received data is [1, 0, 0, 0], then the bit-by-bit multiplication and summation is 1*1+0*0+0*1+0*0=1. The higher the matching degree between the segment of data corresponding to the position and the frame header template data is, the greater the corresponding frame header probability is.

[0050] The terminal needs to keep searching for the forward signal, and when no forward signal is searched, an error frame header index may be acquired due to no actual signal. When the forward signal is searched, the forward signal may be, for example, a satellite / base station DVB signal, and the real frame header can be quickly locked by continuous calculation, because after the signal appears, the correlation calculation result of a position will match the frame header template data, so that the super frame header position can be determined.

[0051] In the embodiment, the super frame header position is located by segmenting the received data, traversing and comparing, and taking the maximum correlation result, so that the position with the highest matching degree to the protocol frame header template can be quickly locked in a complex channel environment, and accurate initial coordinates are provided for super frame synchronization. Meanwhile, the comparison is performed based on the quantized bit-by-bit multiplication and summation of the segment of data and the template, so that subjective judgment error is avoided, and even if there is noise or interference, the most possible real super frame header position can be screened out by the objective standard of the maximum processing result, thereby laying a reliable foundation for subsequent frame format analysis and timing calibration.

[0052] In an optional embodiment of the present application, frame format analysis processing is performed based on the super frame header position, and a corresponding frame type format is obtained, as shown in Figure 3 The method comprises the following steps:

[0053] Step 301: acquiring target data corresponding to the super frame header position.

[0054] Step 302: analyzing the target data according to a preset protocol to determine a corresponding frame type format.

[0055] Specifically, after obtaining the superframe header position, the superframe header position is taken as a reference to intercept the position and a subsequent data segment containing key information as target data. The target data includes not only the synchronization code, check bits and other basic identifiers of the superframe header itself, but also core control fields for defining the superframe structure, such as superframe type coding, frame format identification, and the like.

[0056] In the process of parsing the target data according to the preset protocol, specific fields can be extracted and the meanings thereof can be translated according to the provisions of the DVB protocol for the superframe structure, so as to finally determine the corresponding frame type format. For example, the DVB protocol can include: the 10th-15th bits after the superframe header are frame type identification bits, wherein "0001" corresponds to a basic frame format applicable to low-speed transmission, "0010" corresponds to an extended frame format supporting high-speed transmission, and "0100" corresponds to a hybrid frame format compatible with multiple channels. The terminal will locate the corresponding bit segment in the target data according to this rule, recognize the specific value of the identification bit through decoding, and then match the format type table defined in the protocol, so as to determine the frame type format adopted by the current superframe. Each superframe format type has a corresponding theoretical frame header position.

[0057] In the embodiment, the target data corresponding to the superframe header is accurately obtained, and the frame type format is determined by protocol parsing, which can provide accurate protocol basis for subsequent theoretical frame header position acquisition and time offset calculation, and guarantee the reliability of timing calibration.

[0058] In an optional embodiment of the present application, after obtaining the corresponding frame type format, the method further comprises:

[0059] Based on the frame type format, the size of each physical frame data is determined; decoding processing is performed according to the size of each physical frame data, and it is judged whether the decoding is correct; when the decoding is correct, it is determined that the superframe header position is in an available state; when the decoding is incorrect, it is determined that the superframe header position is in an unavailable state.

[0060] It can be understood that, since the DVB protocol presets explicit physical frame structure specifications for different frame type formats, for example, a certain type of frame type format provides that a single physical frame contains 1024 bytes of data, and the byte data contains a payload and a check bit, and another type provides 2048 bytes, and the frame type format directly determines the total length of the physical frame, the distribution of fields, such as the division of data area and check area.

[0061] Specifically, after the frame type format is acquired, the size of each physical frame data is determined according to a preset format rule, and bit-level decoding processing is performed according to the size of the physical frame data. The intercepted physical frame data can be reversely decoded according to an encoding rule specified by the protocol to obtain a decoding result, and then the correctness of the decoding result is verified through a verification mechanism. The verification mechanism can include CRC verification and parity verification. For example, if the size of the physical frame data is 1024 bytes, the data is first split according to the length of 1024 bytes during decoding, and then the original information is recovered through a decoding algorithm. Finally, it is checked whether the recovered information conforms to the verification rule, for example, whether the check bit matches the data content, to determine whether the decoding is correct. The encoding rule can be convolutional encoding or LDPC encoding.

[0062] When the decoding is correct, it indicates that the structure and content of the physical frame data are consistent with the protocol specification, and the reverse superframe header position is accurate, so it is determined that the superframe header position is in a usable state. When the decoding is incorrect, it means that the physical frame data may be incorrectly intercepted due to the deviation of the superframe header position, or it is interference data, so it is determined that the superframe header position is not usable.

[0063] In the embodiment, the size of the physical frame data is determined through the frame type format, and the usability of the superframe header position is verified by the correctness of the decoding. By means of the frame structure specification and decoding verification logic specified by the protocol, the incorrect frame header position caused by noise interference or synchronization deviation can be accurately filtered, and a reliable reference for subsequent frame format analysis and time offset calculation based on the superframe header position is ensured, thereby reducing the risk of subsequent processing deviation caused by position error from the source.

[0064] In an optional embodiment of the present application, the time offset error value is determined according to the theoretical frame header position and the superframe header position, including:

[0065] The total length of the data transmitted in each millisecond is acquired, and the time offset error value is determined according to the total length, the theoretical frame header position and the superframe header position.

[0066] Specifically, since the data transmission rate is fixed in the DVB system, after the theoretical frame header position and the superframe header position are acquired, the total length of the data transmitted in each millisecond is acquired. After the total length is obtained, the time offset error value is determined in combination with the theoretical frame header position and the superframe header position. This process is essentially to derive the "time deviation" through the "position deviation". The theoretical frame header position is a standard coordinate specified by the protocol, such as the 2000th bit after the start of the superframe. The superframe header position is an actual detected coordinate, such as the 2100th bit after the start of the superframe. The difference (100 bits) between the two is the position deviation. Since the total length per millisecond is known, the time offset error value Δt can be calculated by the following formula:

[0067] Δt = (position - P) / length.

[0068] Wherein, position is the super-frame header position, P is the theoretical frame header position, and length is the total length of data transmitted per millisecond.

[0069] It can be understood that, in the embodiment, the timing characteristics of the forward signal are completely relied on, and the demodulation result of the reverse link is not needed. Even in the initial terminal access stage, when the reverse link is not stable, the time offset error can be calculated independently through the forward data, so as to provide an accurate quantitative reference for subsequent time offset compensation.

[0070] In the embodiment, the total length of data transmitted per millisecond is obtained, and the time offset error value is determined in combination with the theoretical frame header position and the super-frame header position. The accurate conversion relationship from the position difference to the time difference can be established by using the fixed transmission rate, the time offset error is quantified independently based on the forward signal, the dependence on the demodulation state of the reverse link is broken, and timely and accurate error reference is provided for time offset compensation in the terminal access stage.

[0071] In an optional embodiment of the present application, the signaling processing unit performs time offset compensation correction according to the time offset error value to determine a target time offset value, including:

[0072] The signaling processing unit obtains the communication terminal position information and the satellite position information, and determines the target time offset value according to the communication terminal position information, the satellite position information and the time offset error value.

[0073] Specifically, after the communication terminal obtains the time offset error value, the time offset error value can be sent to the signaling processing unit, which can be L1C. The signaling processing unit obtains the communication terminal position information and the satellite position information, which provides a spatial coordinate reference for subsequent time offset correction.

[0074] Wherein, the terminal position information can be obtained by the GPS module built-in in the terminal, and includes accurate geographic coordinates such as longitude, latitude and altitude. The satellite position information can be obtained by extracting SPT (satellite position and time) information from the parsed forward signal, and then calculating the real-time spatial position of the satellite at the current time through the six numbers (orbital parameters) in the SPT. The two sets of position information together constitute the spatial distance reference of the "terminal-satellite" link, and are the basis for distinguishing the normal time delay caused by the spatial distance in the original time offset from the abnormal time offset caused by the signal transmission deviation.

[0075] It can be understood that the above L1C is responsible for processing the control signaling of the physical layer, and undertakes a plurality of key functions. It can realize functions such as satellite search strategy, power control, time-frequency offset synchronization, beam management, and transmission-reception switching. In terms of signaling processing, the L1C interfaces with higher layers (such as the RRC layer) and interacts with data, receives signaling data from the higher layer, and performs physical layer processing such as channel coding and modulation, and then transmits through the physical channel. At the same time, the L1C is also responsible for receiving signaling data on the physical channel, performing demodulation and decoding processing, and then passing it to the higher layer protocol stack.

[0076] The signaling processing unit in this embodiment can master the basic data of the normal propagation delay generated by the spatial distance between the communication terminal and the satellite by acquiring the position information of the communication terminal and the satellite, and can accurately correct the time sequence deviation in signal transmission on the basis of the normal propagation delay in combination with the time offset error value, so as to determine the target time offset value that conforms to the spatial propagation rule and is close to the actual transmission state, and to provide accurate time calibration basis for terminal reverse data transmission, thereby effectively improving the probability of correct demodulation of the reverse signal by the base station.

[0077] In an optional embodiment of the present application, the target time offset value is determined according to the communication terminal position information, the satellite position information, and the time offset error value, and includes:

[0078] The distance between the communication terminal and the satellite is calculated according to the communication terminal position information and the satellite position information.

[0079] The initial time offset is calculated according to the distance divided by the speed of light, and the target time offset value is determined by adding the initial time offset and the time offset error value.

[0080] Specifically, after the communication terminal position information and the satellite position information are acquired, the communication terminal position information and the satellite position information can be represented by three-dimensional coordinates, and the distance between the communication terminal and the satellite can be calculated by the following formula:

[0081]

[0082] Wherein, the communication terminal position information is (x st ,y st ,z st ), and the satellite position information is (x sat ,y sat ,z sat ).

[0083] After the distance between the communication terminal and the satellite is determined, the initial time offset is calculated according to the distance divided by the speed of light, and the target time offset value is determined by adding the initial time offset and the time offset error value to correct the initial time offset, which can be represented by the following formula:

[0084]

[0085] Where d is the distance between the communication terminal and the satellite, c is the speed of light, Δt is the time offset error value, and TA is the target time offset value.

[0086] It should be noted that the target time offset is the final timing reference value used by the communication terminal to calibrate the transmission time when transmitting data in the reverse direction. Its core function is to ensure that the reverse signal sent by the terminal accurately falls into the receiving time slot of the satellite (or base station), avoiding demodulation failure due to timing deviation. The aforementioned initial time offset is calculated based on the spatial position of the communication terminal and the satellite, obtained by dividing the distance between them by the speed of light. For example, at a distance of 3000 kilometers, the initial time offset is about 10 milliseconds, reflecting the "inherent time delay" of the signal propagation in space (which represents an inevitable deviation determined by physical laws). The time offset error value is obtained through forward signal analysis, reflecting the "additional timing offset" caused by channel interference, synchronization deviation, etc. in actual transmission, i.e., the abnormal deviation that needs to be corrected.

[0087] For example, please see Figure 4 As shown, taking the signaling processing unit (LIC) as an example, the DVB terminal searches for satellites. When it receives a DVB signal, it uses a superframe synchronization algorithm to determine the superframe header position. Based on the superframe header position, it performs frame format parsing to obtain the corresponding frame type format. Based on the frame type format, it determines the size of each physical frame data. It performs decoding processing based on the size of each physical frame data and determines whether the decoding is correct. When the decoding is correct, it determines that the superframe header position is in an available state; when the decoding is incorrect, it determines that the superframe header position is in an unavailable state. When the superframe header position is unavailable, the superframe synchronization algorithm is used again to determine the superframe header position. When the superframe header position is available, the theoretical frame header position corresponding to the frame type format is obtained. Based on the theoretical frame header position and the superframe header position, the time offset error value Δt is determined, and then the time offset error value is sent to the LIC so that the LIC can compensate for the time offset error value to determine the target time offset value.

[0088] In the terminal access process of the DVB protocol, "precise synchronization" is a critical stage for timing calibration between the terminal and the base station. However, before this (such as in the initial access stage), the terminal's TA calculation often has errors due to unstable synchronization, channel interference, etc. The role of TA is to allow the terminal to send reverse data in advance (to offset the signal propagation delay). If the TA calculation is inaccurate, the actual delay when the reverse data arrives at the base station will far exceed the tolerance range of the base station's receiving window. For example, the base station expects a delay of 10 microseconds, but the actual arrival delay is 30 microseconds, which will eventually lead to the failure of reverse demodulation by the base station.

[0089] The present application aims at this problem, and the core is "compensating the calculation defects of reverse TA with the known information of forward link": the frame structure of forward link (base station to terminal) is predefined in DVB protocol, for example, the position relationship of superframe header and theoretical frame header is explicitly defined in the protocol. The terminal parses the actual superframe header position through the forward signal, and combines the theoretical frame header position defined in the protocol to directly calculate the delay error of forward link, that is, the deviation of actual received forward frame header from the theoretical time, reflecting the degree of time sequence asynchronization between the terminal and the base station. Since the propagation environment of forward and reverse links has relevance, the delay characteristics of the same path are consistent, and this forward delay error can be used as the basis for compensating the reverse TA. The terminal superimposes the error to the original TA calculation value to dynamically adjust the advance amount of reverse transmission, so that the actual delay of reverse data reaching the base station falls within the receiving window.

[0090] The time delay correction value carried in the correction information descriptor is calculated based on the demodulation of reverse data at the base station side. If the reverse data delay error is large, the reverse link cannot be directly demodulated, resulting in link disconnection. By adjusting the initial time delay with the time deviation error value calculated in the present application, the problem of link disconnection caused by large reverse link delay can be solved, the scenario of large delay that cannot be covered by the correction information descriptor is supplemented, and the stability of reverse communication is improved.

[0091] In the present embodiment, the distance between the communication terminal and the satellite is calculated based on the position information of the two, and the initial time deviation obtained by combining the speed of light, so as to accurately capture the inherent time delay of signal propagation; on this basis, the time deviation error value is superimposed for correction, which further compensates for the time sequence deviation in actual transmission. The finally determined target time deviation value not only conforms to the physical propagation law, but also fits the real transmission state, thereby providing an accurate time reference for the terminal reverse data transmission and significantly improving the probability of correct demodulation of reverse signal by the satellite.

[0092] In an optional embodiment of the present application, the received data can also be subjected to superframe synchronization processing to obtain the superframe header of the superframe header position of the received data and superframe data;

[0093] Starting from the superframe header of the received data, N pieces of data are extracted according to a preset rule; each piece of data includes M data, and (N*M) < single superframe data length;

[0094] All data in the N pieces of data are subjected to real and imaginary part analysis processing to calculate an average power value;

[0095] The average power value is converted into binary, and a highest bit index value is determined; the highest bit index value is an index value corresponding to the highest significant bit after conversion into binary; a shift amount is calculated according to the highest bit index value; a target factor of time domain gain adjustment is obtained, and the target factor is subtracted by the shift amount to obtain the power adjustment factor; the power adjustment factor is used to realize dynamic adjustment of received data; when the average power value is equal to 2 raised to the power of the highest bit index value, and the highest bit index value is even, the highest bit corresponding to the highest bit index value is right shifted by one bit to obtain the shift amount; when the average power value is not equal to 2 raised to the power of the highest bit index value, or the highest bit index value is not even, the highest bit corresponding to the highest bit index value is right shifted by one bit and then added by one to obtain the shift amount.

[0096] The entire superframe data is moved left by the power adjustment factor bit positions to perform gain control on the entire superframe data, and gain-controlled data is obtained.

[0097] It should be understood that, although each step in the flowchart is shown in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, at least part of the steps in the figure can include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these sub-steps or stages is not necessarily sequential, but can be alternately executed with at least part of other steps or sub-steps or stages of other steps.

[0098] In another embodiment provided in the present application, a reverse time offset compensation device is also provided, please refer to Figure 5 The device comprises:

[0099] The determining module 810 is configured to determine a superframe header position by using a superframe synchronization algorithm when a digital video broadcast (DVB) terminal searches for a satellite.

[0100] The analyzing module 820 is configured to perform frame format analysis processing based on the superframe header position to obtain a corresponding frame type format.

[0101] The obtaining module 830 is configured to obtain a theoretical superframe header position corresponding to the frame type format according to the frame type format when the superframe header position is in an available state.

[0102] The compensation module 840 is configured to determine a time offset error value according to the theoretical superframe header position and the superframe header position, and send the time offset error value to a signaling processing unit, so that the signaling processing unit performs time offset compensation correction according to the time offset error value to determine a target time offset value.

[0103] Optionally, the determining module 810 is specifically used for:

[0104] determining a plurality of segment data from the received data;

[0105] performing bit-by-bit multiplication and summation processing on each segment data and a frame header template data specified by a protocol to obtain a processing result, by traversing all the received data;

[0106] taking the position of the segment data with the largest processing result as the super frame header position.

[0107] Optionally, the parsing module 820 is specifically used for:

[0108] obtaining target data corresponding to the super frame header position;

[0109] parsing the target data according to a preset protocol to determine a corresponding frame type format.

[0110] Optionally, the apparatus is specifically used for:

[0111] determining the size of each physical frame data based on the frame type format;

[0112] performing decoding processing according to the size of each physical frame data and determining whether the decoding is correct;

[0113] when the decoding is correct, determining that the super frame header position is in an available state;

[0114] when the decoding is incorrect, determining that the super frame header position is in an unavailable state.

[0115] Optionally, the compensation module 840 is specifically used for:

[0116] the signaling processing unit obtains communication terminal position information and satellite position information;

[0117] determining a target time offset value according to the communication terminal position information, the satellite position information and a time offset error value.

[0118] Optionally, the compensation module 840 is further used for:

[0119] calculating the distance between the communication terminal and the satellite according to the communication terminal position information and the satellite position information;

[0120] calculating an initial time offset by dividing the distance by the speed of light, and adding the initial time offset and the time offset error value to determine the target time offset value.

[0121] The specific limitations of the reverse timing skew compensation device can refer to the limitations of the reverse timing skew compensation method described above, which will not be repeated here. Each module in the reverse timing skew compensation device can be implemented by software, hardware, and a combination thereof, in whole or in part. The above modules can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory in the computer device in software form, so that the processor calls and executes the operations corresponding to each of the above modules.

[0122] In one embodiment, a communication terminal device is provided, and an internal structure diagram of the communication terminal can be as shown in Figure 1 The communication terminal includes a processor, a memory, a network interface, and a database connected by a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the communication terminal includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium to run. The database of the communication terminal is used to store data. The network interface of the communication terminal is used to communicate with external terminals through network connection. The computer program is executed by the processor to implement a reverse timing skew compensation method as described above. It includes a memory and a processor, the memory stores a computer program, and the processor executes the computer program to implement any step in the reverse timing skew compensation method described above.

[0123] In one embodiment, a computer readable storage medium is provided, and a computer program is stored on the computer readable storage medium. The computer program is executed by the processor to implement any step in the reverse timing skew compensation method described above.

[0124] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0125] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0126] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks Figure 1 means for functionally implementing the steps listed in the flowchart block or blocks.

[0127] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks ​ means for functionally implementing the steps listed in the flowchart block or blocks.

[0128] While the preferred embodiments of the application have been described, additional variations and modifications can be employed by those skilled in the art. Therefore, the appended claims intend to cover all such modifications and variations as fall within the true spirit and scope of the application.

[0129] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A reverse time offset compensation method, characterized in that, The reverse time offset compensation method includes: When the digital video broadcasting (DVB) terminal searches for satellites, it uses a superframe synchronization algorithm to determine the superframe header position. Frame format parsing is performed based on the superframe header position to obtain the corresponding frame type format; When the superframe header position is available, the theoretical frame header position corresponding to the frame type format is obtained according to the frame type format. Based on the theoretical frame header position and the superframe header position, the time offset error value is determined and sent to the signaling processing unit, so that the signaling processing unit can perform time offset compensation correction based on the time offset error value and determine the target time offset value.

2. The reverse time offset compensation method according to claim 1, characterized in that, The superframe header position is determined using a superframe synchronization algorithm, including: Multiple data segments are determined from the received data; Traverse all received data, perform bitwise multiplication and summation on each segment of data and the frame header template data specified in the protocol, and obtain the processing result; The position corresponding to the segment with the largest processing result is taken as the superframe header position.

3. The reverse time offset compensation method according to claim 1, characterized in that, Based on the superframe header position, frame format parsing is performed to obtain the corresponding frame type format, including: Obtain the target data corresponding to the superframe header position; The target data is parsed according to a preset protocol to determine the corresponding frame type format.

4. The reverse time offset compensation method according to claim 1, characterized in that, After obtaining the corresponding frame type format, the method further includes: Based on the frame type format, determine the size of each physical frame data; Decode the data based on the size of each physical frame and determine whether the decoding is correct. When the decoding is correct, it is determined that the superframe header position is in an available state; When a decoding error occurs, it is determined that the superframe header position is in an unavailable state.

5. The reverse time offset compensation method according to claim 1, characterized in that, Based on the theoretical frame header position and the superframe header position, the time offset error value is determined, including: Get the total length of data transmitted per millisecond; The time offset error value is determined based on the total length, the theoretical frame header position, and the superframe header position.

6. The reverse time offset compensation method according to claim 1, characterized in that, The signaling processing unit performs time offset compensation correction based on the time offset error value to determine the target time offset value, including: The signaling processing unit acquires the location information of the communication terminal and the satellite location information; The target time offset value is determined based on the communication terminal location information, satellite location information, and the time offset error value.

7. The reverse time offset compensation method according to claim 6, characterized in that, Based on the communication terminal location information, satellite location information, and the time offset error value, the target time offset value is determined, including: Calculate the distance between the communication terminal and the satellite based on the communication terminal location information and the satellite location information; The initial time offset is calculated by dividing the distance by the speed of light, and the initial time offset is added to the time offset error value to determine the target time offset value.

8. A reverse time offset compensation device, characterized in that, The reverse time offset compensation device includes: The determination module is used to determine the superframe header position using a superframe synchronization algorithm when the digital video broadcasting (DVB) terminal searches for satellites. The parsing module is used to perform frame format parsing based on the superframe header position to obtain the corresponding frame type format; The acquisition module is used to acquire the theoretical frame header position corresponding to the frame type format according to the frame type format when the superframe header position is in an available state; The compensation module is used to determine the time offset error value based on the theoretical frame header position and the superframe header position and send it to the signaling processing unit so that the signaling processing unit can perform time offset compensation correction based on the time offset error value and determine the target time offset value.

9. A communication terminal device, comprising: A memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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