Navigation message broadcasting method and device for multi-order LDPC encoding

Abstract

The application provides a navigation message broadcasting method and device based on multi-ary LDPC coding. The method is related to the field of signal processing, and comprises the following steps: obtaining original navigation message information, and splitting the original navigation message information into multi-ary navigation message information streams based on the number of information symbols of LDPC and the bit width of information symbols of LDPC in a finite field; performing multi-path parallel finite field multiplication operation on the multi-ary navigation message information streams and non-unit matrices in a preset generating matrix based on a preset hardware coding parallel degree in the finite field to obtain a navigation message check information matrix; splicing the multi-ary navigation message information streams and supervision symbols to obtain error correction coded navigation message; and broadcasting the error correction coded navigation message.

Description

Technical Field

[0001] This invention relates to the field of signal processing, and in particular to a method and apparatus for broadcasting navigation messages using multi-level LDPC encoding. Background Technology

[0002] Satellite navigation signals undergo significant power attenuation during their long-distance transmission through the troposphere and ionosphere, making them highly susceptible to various types of interference and noise. Satellite navigation messages contain useful information modulated onto navigation signals, including crucial data such as satellite clock bias parameters, satellite broadcast ephemeris parameters, group delay correction parameters, and simplified almanacs. Irreversible loss can occur if environmental factors or interference affect data reception.

[0003] When satellite navigation systems were initially designed, the target users were in open outdoor environments with no obstacles between the satellite and the receiving terminal, and the channel conditions were stable. Therefore, early navigation message coding used binary LDPC codes, which had near-optimal performance under Gaussian white noise channels, to encode message subframes, thereby improving demodulation performance in mobile receiving environments and challenging conditions. However, as the application environment of satellite navigation systems expanded to urban, indoor, and jungle scenarios, reflections, blockages, or mobile reception in complex environments caused the channel to exhibit fading characteristics, placing higher demands on message coding.

[0004] Currently, in the field of satellite navigation, the BeiDou Global Navigation Satellite System (BDS-3) and my country's deployed low-Earth orbit (LEO) internet satellite messages both employ multi-level low-density parity check (LDPC) coding to improve the adaptability of satellites to fading channels. According to the BeiDou system's space signal interface control document, multiple frequency points, including B1C, B2a, B2b, and LEO satellite internet messages, all use multi-level low-density parity check (LDPC) as the primary channel coding form. However, multi-level LDPC channel coding often employs a software serial computation method, resulting in significant computational complexity and time consumption. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the present invention aims to provide a method and apparatus for broadcasting navigation messages using multi-level LDPC encoding, which can ensure stable and reliable information acquisition capabilities even under special conditions such as navigation satellite handover or short-term signal interruption, improve navigation message transmission rate, and enhance the high-precision positioning service performance of satellite navigation systems.

[0006] To achieve the above-mentioned objective, this invention provides a method for broadcasting navigation messages using multi-level LDPC encoding, comprising the following steps:

[0007] Obtain the original navigation message information with a total length of k·b bits, and based on the preset number of information symbols k of the low-density parity-check code LDPC, and the finite field GF(2) of LDPC... b The information symbol bit width b under the given conditions will split the original navigation message information into k 2-bit segments. b Multi-ary navigation message information flow S with radix notation;

[0008] In the finite field GF(2) b Under the condition that, based on the preset hardware coding parallelism m, the multi-level navigation message information stream S is multiplied by the non-identity matrix W in the preset generation matrix in m parallel finite field operations to obtain the navigation message verification information matrix P; the non-identity matrix W is the matrix obtained by dividing the preset generation matrix into blocks and removing the identity matrix part.

[0009] The multi-level navigation message information stream S is concatenated with the check code p to obtain the error-corrected navigation message D; the check code p is the element in the navigation message verification information matrix P within the finite field GF(2). b The result is obtained by summing the columns below.

[0010] The navigation message D after error correction coding is broadcast.

[0011] According to one technical solution of the present invention, the process of obtaining the original navigation message information includes:

[0012] The original navigation message information is received via a serial port, and the transmission level of the original navigation message information is sampled and aligned according to the preset clock division counting threshold corresponding to the baud rate of the original navigation message information in order to recover the original navigation message information.

[0013] According to one technical solution of the present invention, the generating matrix is ​​the result of applying the verification matrix of the navigation system to the finite field GF(2). b The matrix obtained after Gaussian elimination.

[0014] According to one technical solution of the present invention, after concatenating the multi-level navigation message information stream S with the check code p to obtain the error-corrected coded navigation message D, the method further includes:

[0015] The error-corrected and encoded navigation message D is alternately written to at least two buffer areas for ping-pong caching.

[0016] According to one technical solution of the present invention, broadcasting the error-corrected coded navigation message D includes:

[0017] According to the message broadcast rate, the error-corrected and coded navigation messages D that have been written to the buffer are read alternately and broadcast.

[0018] According to one technical solution of the present invention, the m-way parallel finite field multiplication operation includes:

[0019] Using m finite field multiplication units, the m matrix elements of the corresponding row in the non-identity matrix W are read in a column-parallel and row-serial manner, and compared with the currently read 2 b The product operation is performed simultaneously with the number base symbol;

[0020] Complete the process for the k 2s sequentially. b The operations on the number system symbols yield the navigation message verification information matrix P, which contains k×(nk) product operation results.

[0021] According to one technical solution of the present invention, the process of obtaining the supervision symbol p includes:

[0022] For each column element of the navigation message verification information matrix P, respectively, in the finite field GF(2) b Performing an addition operation yields nk twos. b Number system symbols;

[0023] The nk units of 2 b The number symbols are combined in the column order of the navigation message verification information matrix P to obtain the supervision code p; where n is the total code length of the navigation message D after error correction coding.

[0024] According to one technical solution of the present invention, broadcasting the error-corrected coded navigation message D includes:

[0025] A ranging code is generated according to a preset code rate, and the message transmission rate is calculated.

[0026] The error-corrected navigation message D is read from the buffer according to the message broadcast rate, so that the read error-corrected navigation message D is in phase with the ranging code;

[0027] The navigation message D after error correction coding is spread by direct sequence and carrier modulation using the ranging code. After power adjustment and up-conversion processing, the navigation radio frequency signal is finally output and broadcast.

[0028] The present invention also provides a navigation message broadcasting device with multi-level LDPC encoding, comprising:

[0029] The information splitting module is used to obtain the original navigation message information with a total length of k·b bits, and based on the preset number of information symbols k of the low-density parity-check code LDPC, and the finite field GF(2) of LDPC... b The information symbol bit width b under the given conditions will split the original navigation message information into k 2-bit segments. b Multi-ary navigation message information flow S with radix notation;

[0030] Parallel encoding module, used in the finite field GF(2 b Under the condition that, based on the preset hardware coding parallelism m, the multi-level navigation message information stream S is multiplied by the non-identity matrix W in the preset generation matrix in m parallel finite field operations to obtain the navigation message verification information matrix P; the non-identity matrix W is the matrix obtained by dividing the preset generation matrix into blocks and removing the identity matrix part.

[0031] The codeword concatenation module is used to concatenate the multi-level navigation message information stream S with the check code p to obtain the error-corrected navigation message D; the check code p is the element in the navigation message verification information matrix P in the finite field GF(2). b The result is obtained by summing the columns below.

[0032] The broadcast module is used to broadcast the error-corrected and encoded navigation message D.

[0033] The present invention provides a method and apparatus for broadcasting navigation messages using multi-level LDPC encoding, which has the following beneficial effects:

[0034] 1. This invention converts the input message data stream into a multi-base bit-width codeword stream and uses a column-parallel and row-serial reading method to generate the matrix. This allows for unified encoding in the encoding core according to multi-base granularity, which can effectively reduce computation time and achieve low-latency computation.

[0035] 2. The present invention makes reasonable use of the navigation message coding mapping relationship, reduces the number of particle number buffers in the generation matrix, reduces computational complexity, saves cache resources, and effectively completes multi-level LDPC coding operations.

[0036] 3. This invention employs parameter configuration and modular design to achieve message coding design for different navigation systems (including GNSS satellite navigation systems and low-Earth orbit satellite internet navigation systems), effectively reducing software modification complexity and improving software adaptability. It can be used in the design of related navigation satellite payloads to achieve on-board channel coding, reduce satellite-to-ground information uploading time, increase navigation signal broadcasting efficiency, and improve the overall stability of the satellite system. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0038] Figure 1 This schematic diagram illustrates the structure of a navigation message broadcasting device with multi-level LDPC encoding according to an embodiment of the present invention.

[0039] Figure 2 This diagram illustrates the principle of splitting the multi-level navigation message information stream S in a multi-level LDPC encoded navigation message broadcasting method according to an embodiment of the present invention.

[0040] Figure 3 This diagram illustrates the principle of m-path parallel finite field multiplication operations in a navigation message broadcasting method using multi-level LDPC encoding according to an embodiment of the present invention.

[0041] Figure 4 The schematic diagram illustrates the timing of m-path parallel finite field multiplication operations in a navigation message broadcasting method with multi-level LDPC encoding according to an embodiment of the present invention.

[0042] Figure 5 This diagram illustrates the principle of a message broadcasting module in a navigation message broadcasting method using multi-level LDPC encoding according to an embodiment of the present invention. Detailed Implementation

[0043] The description of the embodiments in this specification should be taken in conjunction with the accompanying drawings, which should form part of the complete specification. In the drawings, the shape or thickness of the embodiments may be exaggerated and may be indicated in a simplified or convenient manner. Furthermore, parts of the various structures in the drawings will be described separately; it is worth noting that elements not shown in the figures or not described in words are in a form known to those skilled in the art.

[0044] The descriptions of the embodiments herein, including any references to directions and orientations, are for ease of description only and should not be construed as limiting the scope of the invention. The following description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the invention is defined by the claims. Figures 1-5 As shown; Specific Implementation Method 1

[0046] This embodiment of a method for broadcasting navigation messages using multi-level LDPC encoding includes the following steps:

[0047] Obtain the original navigation message information with a total length of k·b bits, and based on the preset number of information symbols k of the low-density parity-check code LDPC, and the finite field GF(2) of LDPC... b The information symbol width b under the given conditions splits the original navigation message into k 2-bit segments. b Multi-ary navigation message information flow S with radix notation;

[0048] In the finite field GF(2) b Under the premise of a preset hardware coding parallelism m, the multi-level navigation message information stream S is multiplied by the non-identity matrix W in the preset generator matrix in m parallel finite field operations to obtain the navigation message verification information matrix P; the non-identity matrix W is the matrix obtained by dividing the preset generator matrix into blocks and removing the identity matrix part.

[0049] The multi-level navigation message information stream S is concatenated with the check code p to obtain the error-corrected navigation message D; the check code p is the result of the elements in the navigation message verification information matrix P in the finite field GF(2). b The result is obtained by summing the columns below.

[0050] The navigation message D after error correction coding is broadcast.

[0051] Specifically, the method for broadcasting navigation messages using multi-level LDPC encoding according to this embodiment includes the following steps:

[0052] Step S1: Receive navigation message information, split the received information, and form a multi-level navigation message information stream;

[0053] According to the "BeiDou System Space Signal Interface Control Document," both BeiDou-3 and low-Earth orbit internet satellite navigation systems use low-density parity-check (LDPC) codes as the primary channel coding method for downlink messages. This applies to the original navigation message information excluding the synchronization header. All participate in the finite field of the original polynomial. coding.

[0054] Multi-base codeword splitting, such as Figure 2 As shown. After receiving the original navigation message information, the finite field is encoded according to the LDPC encoding of the navigation message. and The information in the middle is used to split the original navigation message information into multiple bases, and the resulting multiple base navigation message information stream is as follows: Participating in finite field operations, where and middle correspond, Code words (information symbols) in Chinese Both are 2 6 The number system and bit width are b bits (taking b=6 as an example). The multi-base navigation message information stream is then buffered into a register, and subsequent reading and operation operations are performed on it according to the degree of parallelism.

[0055] Step S2: Calculate the generator matrix, and optimize its storage and serial-parallel reading.

[0056] Based on the generator matrix Characteristics of generating matrices It is a unit array Non-identity matrix To reduce storage and computational resource consumption, the composition only applies to non-identity matrices. Store the non-identity matrix W as a preset generator matrix for subsequent calculations.

[0057] Step S3: Perform finite field multi-ary LDPC encoding operation on the multi-ary navigation message information stream S and the generation matrix (non-identity matrix W) to complete the generation of the navigation message verification information matrix P.

[0058] The navigation message verification information matrix P uses multi-level LDPC encoding, and each message code character consists of b bits (taking b=6 as an example), defined in the original polynomial. finite field GF( The non-identity matrix W is read by m finite field multiplication units in a column-parallel, row-serial manner, and then computed through the finite field. * Generate a k×(nk) dimension navigation message verification information matrix P.

[0059] Step S4: Perform calculations on the encoded information stream and complete the ping-pong buffering.

[0060] Due to the generating matrix It is the identity matrix Non-identity matrix Composition, identity matrix It consists of multiple Composed of identity matrices of varying sizes, capable of generating multi-level navigation message information stream S; non-identity matrices Generate a parity check sequence. The mapping relationship of the system code ensures that the first k symbols of the error-corrected navigation message D are the same as the multi-level navigation message information flow S, and the last nk symbols are the check symbols obtained by column-wise accumulation of the navigation message check information matrix P. (i.e., parity check sequence). Then, the multi-level navigation message information stream S and the check code are compared. After splicing, the navigation message D with error-correcting coding capability is completed. ,Right now:

[0061]

[0062] The error-corrected navigation message D is then stored using a ping-pong method. Based on the characteristics of BeiDou-3 navigation message information, the maximum message rate is 1000bps. Therefore, a 16-bit wide, 64-bit deep RAM core is required for ping-pong operations to increase the error tolerance of the message information.

[0063] Step S5: Based on the ranging code rate and message broadcasting rate at each frequency point, read the error-corrected and coded navigation message D from the ping-pong buffer, and output the navigation radio frequency signal after direct-sequence spread spectrum, carrier modulation, power adjustment and up-conversion processing and broadcast it. Specific Implementation Method Two

[0065] In this embodiment, the process of obtaining the original navigation message information includes:

[0066] The system receives the original navigation message information via serial port and samples and aligns the transmission level of the original navigation message information according to the preset clock division counting threshold corresponding to the baud rate of the original navigation message information, so as to recover the original navigation message information.

[0067] Specifically, the reception of the original navigation message information can be accomplished by controlling the bit counter clk_Div_cnt=f (a preset clock division count threshold), where the preset clock division count threshold f is based on... Original navigation message information The baud rate is adjusted. Taking a system clock of 180MHz as an example, the selection of the preset clock division counting threshold f is shown in Table 1:

[0068] Table 1. Correspondence between baud rate and preset clock division counting threshold f

[0069] baud rate 115200 256000 512000 1000000 f 1561 702 350 179 Specific Implementation Method 3

[0071] In this embodiment, the generator matrix is ​​generated by applying the verification matrix of the navigation system to the finite field GF(2). b The matrix obtained after Gaussian elimination.

[0072] Specifically, this involves the specific process of calculating the generating matrix in step S2.

[0073] Based on the verification matrix H provided by the required navigation system frequency, it is transformed into a generator matrix G through Gaussian elimination and stored in a buffer. The navigation system includes satellite navigation systems such as BeiDou, GPS, GLONASS, Galileo, and low-Earth orbit satellite internet. Compatibility between different navigation systems can be achieved by configuring parameters k and b and loading verification matrices H at different frequencies.

[0074] For example, according to the BeiDou Navigation System's verification matrix given in the "BeiDou System Space Signal Interface Control Document", Both have a row weight of 4 and a column weight of 3. After error correction coding according to the linear block code calculation method, the navigation message c is obtained by finite field operations on the multi-base navigation message information flow S and the generator matrix G:

[0075]

[0076] Check matrix of linear block code , check matrix Transform into a system form, using Left multiplication The parity-check matrix on the right is the identity matrix. ,in It is an identity matrix; thus, we obtain the matrix. .

[0077] Among them, the theoretically corrected navigation message after coding is However, since only the non-identity matrix W is stored in step S2 to reduce storage and computational resource consumption, there is no need to perform finite field multiplication on the identity matrix in step S3. Instead, the multi-base navigation message information stream S is directly hardware-concatenated with the generated supervision code p to construct the error-corrected navigation message D. Specific Implementation Method Four

[0079] In this embodiment, after concatenating the multi-level navigation message information stream S with the check code p to obtain the error-corrected navigation message D, the method further includes:

[0080] After error correction coding, the navigation message D is alternately written to at least two buffers for ping-pong caching. Detailed Implementation Method Five

[0082] In this embodiment, broadcasting the error-corrected navigation message D includes:

[0083] According to the message broadcast rate, the navigation message D, which has been written into the buffer, is read alternately and then broadcast. Specific Implementation Method Six

[0085] In this embodiment, m-way parallel finite field multiplication operations are performed, including:

[0086] Using m finite field multiplication units, the m matrix elements of the corresponding row in the non-identity matrix W are read in a column-parallel and row-serial manner, and compared with the currently read 2 b The product operation is performed simultaneously with the number base symbol;

[0087] Complete the k 2s in sequence b The operations on the number system symbols yield a navigation message verification information matrix P containing the results of k×(nk) product operations.

[0088] Specifically, the m-way parallel finite field multiplication operation is calculated through the check bit calculation module, which is the core of the entire encoder, using the finite field GF( The design is described below using ) as an example:

[0089] This module receives codeword information Dian (multi-level navigation message information stream S) and matrix. The generator factor LDPC_W, codeword information Dian is entered as a 6-bit wide, non-identity matrix. Reading is performed using a parallel approach between columns and a serial approach between rows, and computation is performed using finite field methods. * Generate navigation message verification information matrix P.

[0090] The specific working sequence of this module is as follows: Figure 4 As shown.

[0091] clk_cnt is a modulo-6 counter;

[0092] Dian_flag is the value of the message Dian(clk_cnt);

[0093] When clk_cnt=0, LDPC_W_flag takes the value of LDPC_W[5], and at other times it takes the value of LDPC_W2[5].

[0094] When LDPC_Wflag is high, LDPC_W1 is shifted left by one bit; otherwise, it is taken as LDPC_W2 shifted left by one bit.

[0095] When LDPC_Wflag is high, LDPC_W2 ;

[0096] P_reg during Dian_flag ,otherwise ;

[0097] When clk_cnt=5, take P= ;

[0098] It involves parallel operations of m original polynomial modules (finite field multiplication units), thus yielding the navigation message verification information matrix P composed of 6-bit verification symbols as follows:

[0099]

[0100] Located in the i-th row and j-th column of the navigation message verification information matrix P, 2 b The radix is ​​checked for the sign, and each serial multiplication module completes the i-th row of the data vector. The product operation of finite fields. Represents the row index of the multi-level navigation message information flow S; This indicates the index of the supervised symbol column. Detailed Implementation Method Seven

[0102] In this embodiment, the process of obtaining the supervision symbol p includes:

[0103] For each column element of the navigation message verification information matrix P, in the finite field GF(2) b Performing an addition operation yields nk twos. b Number system symbols;

[0104] nk times 2 b The number symbols are combined in column order according to the navigation message verification information matrix P to obtain the check code p; where n is the total code length of the navigation message D after error correction coding.

[0105] Specifically, this involves the supervision code in step S4. The specific calculation process.

[0106] Elements in navigation message verification information matrix P It is the result of a single-point finite field operation, and needs to be sorted according to the columns in the finite field GF(2). b The supervised code is obtained by summing the results. .

[0107] The specific calculation method is as follows: the check code corresponding to the j-th column. The l-th bit ( The following conditions must be met: The bitwise XOR relationship between the elements in the j-th column of the navigation message verification information matrix P must be satisfied.

[0108]

[0109] After the l-th bit of all k elements in column j is XORed and summed, the calculated b bits are concatenated bit by bit to restore the corresponding j-th 2. b Hexadecimal check unit :

[0110]

[0111] The nk numbers of 2 are calculated by combining them in column order. b The number system symbols are used to ultimately obtain the check symbol vector. . Detailed Implementation Method Eight

[0113] In this embodiment, broadcasting the error-corrected navigation message D includes:

[0114] A ranging code is generated based on a preset code rate, and the message transmission rate is calculated.

[0115] Read the error-corrected navigation message D from the buffer according to the message broadcast rate, so that the read error-corrected navigation message D is in phase with the ranging code;

[0116] The navigation message D, after error correction coding, is spread spectrum and carrier modulated using ranging code. After power regulation and up-conversion processing, the navigation radio frequency signal is finally output and broadcast.

[0117] Specifically, this involves the process of broadcasting the error-corrected navigation message D in step S5.

[0118] like Figure 5 As shown, operations such as code clocking, message reading, and ranging code generation are completed based on the system clock and the code rate and message rate of navigation signals at each frequency.

[0119] The serial data stream after error correction coding is subjected to BPSK-DSSS direct sequence spread spectrum, signal modulation, power regulation and up-conversion to ultimately achieve accurate broadcasting of navigation messages.

[0120] The process involves generating ranging codes based on the code rates at each frequency point, simultaneously calculating their message transmission rates, and timely reading the electronically corrected navigation message D from the RAM core. This ensures that the read message information is in phase with the ranging code and is modulated onto a sinusoidal carrier, achieving BPSK-DSSS direct-sequence spread spectrum for the message data. The mathematical expression is as follows:

[0121]

[0122] Where P s For spread spectrum signal power, To correct errors in the encoded message, For ranging code, This represents the angular frequency of a sinusoidal carrier. The above description enables the accurate broadcasting of navigation messages encoded using low-latency multi-level LDPC channels. Detailed Implementation Method Nine

[0124] This embodiment provides a navigation message broadcasting device with multi-level LDPC encoding, including:

[0125] The information splitting module is used to obtain the original navigation message information with a total length of k·b bits, and based on the preset number of information symbols k of the low-density parity-check code LDPC, and the finite field GF(2) of LDPC... b The information symbol width b under the given conditions splits the original navigation message into k 2-bit segments. b Multi-ary navigation message information flow S with radix notation;

[0126] Parallel encoding module, used in the finite field GF(2 b Under the premise of a preset hardware coding parallelism m, the multi-level navigation message information stream S is multiplied by the non-identity matrix W in the preset generator matrix in m parallel finite field operations to obtain the navigation message verification information matrix P; the non-identity matrix W is the matrix obtained by dividing the preset generator matrix into blocks and removing the identity matrix part.

[0127] The codeword concatenation module is used to concatenate the multi-level navigation message information stream S with the check code p to obtain the error-corrected navigation message D; the check code p is the element in the navigation message verification information matrix P within the finite field GF(2). b The result is obtained by summing the columns below.

[0128] The broadcast module is used to broadcast the error-corrected and coded navigation message D.

[0129] In specific implementation, this invention can be as follows: Figure 2 and Figure 3 As shown, the code rate of the multi-level LDPC encoding is set to 1 / 2, i.e., n=2k. At this time, the non-identity matrix W is a k×k square matrix. The hardware encoding parallelism is set to m=k=nk, that is, the number of hardware multiplication units is equal to the number of information symbols and the number of check symbols, forming a fully parallel processing architecture. This architecture can complete the multiplication of an entire row of finite fields in one cycle, maximizing the reduction of encoding latency.

[0130] Furthermore, it should be noted that the present invention can be provided as a method, apparatus, or computer program product. Therefore, embodiments of the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0131] Embodiments of the present invention are described with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0132] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing terminal equipment to cause a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0133] It should also be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0134] Finally, it should be noted that the above description represents a preferred embodiment of the present invention. It should be pointed out that although preferred embodiments have been described, those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles described herein. These improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. A method for broadcasting navigation messages using multi-level LDPC encoding, characterized in that the steps include... include: Obtain the original navigation message information with a total length of k·b bits, and based on the preset number of information symbols k of the low-density parity-check code LDPC, and the finite field GF(2) of LDPC... b The information symbol bit width b under the given conditions will split the original navigation message information into k 2-bit segments. b Multi-ary navigation message information flow S with radix notation; In the finite field GF(2) b Under the condition that, based on the preset hardware coding parallelism m, the multi-level navigation message information stream S is multiplied by the non-identity matrix W in the preset generation matrix in m parallel finite field operations to obtain the navigation message verification information matrix P; the non-identity matrix W is the matrix obtained by dividing the preset generation matrix into blocks and removing the identity matrix part. The multi-level navigation message information stream S is concatenated with the supervision code p to obtain the error-corrected navigation message D; The supervision code p is the element in the navigation message verification information matrix P within the finite field GF(2). b The result is obtained by summing the columns below. The navigation message D after error correction coding is broadcast.

2. The method for broadcasting navigation messages using multi-level LDPC encoding according to claim 1, characterized in that, The process of obtaining the original navigation message information includes: The original navigation message information is received via a serial port, and the transmission level of the original navigation message information is sampled and aligned according to the preset clock division counting threshold corresponding to the baud rate of the original navigation message information in order to recover the original navigation message information.

3. The method for broadcasting navigation messages using multi-level LDPC encoding according to claim 1, characterized in that, The generator matrix is ​​the resultant matrix of the navigation system in the finite field GF(2). b The matrix obtained after Gaussian elimination.

4. The method for broadcasting navigation messages using multi-level LDPC encoding according to claim 1, characterized in that, After concatenating the multi-level navigation message information stream S with the check code p to obtain the error-corrected navigation message D, the following steps are also included: The error-corrected and encoded navigation message D is alternately written to at least two buffer areas for ping-pong caching.

5. The method for broadcasting navigation messages using multi-level LDPC encoding according to claim 4, characterized in that, Broadcasting the error-corrected and coded navigation message D includes: According to the message broadcast rate, the error-corrected and coded navigation messages D that have been written to the buffer are read alternately and broadcast.

6. The method for broadcasting navigation messages using multi-level LDPC encoding according to claim 1, characterized in that, The m-way parallel finite field multiplication operation includes: Using m finite field multiplication units, the m matrix elements of the corresponding row in the non-identity matrix W are read in a column-parallel and row-serial manner, and compared with the currently read 2 b The number system symbols are used simultaneously for product operations; Complete the process for the k 2s sequentially. b The operations on the number system symbols yield the navigation message verification information matrix P, which contains k×(nk) product operation results.

7. The method for broadcasting navigation messages using multi-level LDPC encoding according to claim 6, characterized in that, The process of obtaining the supervised symbol p includes: For each column element of the navigation message verification information matrix P, respectively, in the finite field GF(2) b Performing an addition operation yields nk twos. b Number system symbols; The nk units of 2 b The number symbols are combined in the column order of the navigation message verification information matrix P to obtain the supervision code p; where n is the total code length of the navigation message D after error correction coding.

8. The method for broadcasting navigation messages using multi-level LDPC encoding according to claim 5, characterized in that, Broadcasting the error-corrected and coded navigation message D includes: A ranging code is generated according to a preset code rate, and the message transmission rate is calculated. The error-corrected navigation message D is read from the buffer according to the message broadcast rate, so that the read error-corrected navigation message D is in phase with the ranging code; The navigation message D after error correction coding is spread by direct sequence and carrier modulation using the ranging code. After power adjustment and up-conversion processing, the navigation radio frequency signal is finally output and broadcast.

9. A navigation message broadcasting device with multi-level LDPC encoding, characterized in that, include: The information splitting module is used to obtain the original navigation message information with a total length of k·b bits, and based on the preset number of information symbols k of the low-density parity-check code LDPC, and the finite field GF(2) of LDPC... b The information symbol bit width b under the given conditions will split the original navigation message information into k 2-bit segments. b Multi-ary navigation message information flow S with radix notation; Parallel encoding module, used in the finite field GF(2 b Under the condition that, based on the preset hardware coding parallelism m, the multi-level navigation message information stream S is multiplied by the non-identity matrix W in the preset generation matrix in m parallel finite field operations to obtain the navigation message verification information matrix P; the non-identity matrix W is the matrix obtained by dividing the preset generation matrix into blocks and removing the identity matrix part. The codeword splicing module is used to splice the multi-level navigation message information stream S with the supervision code p to obtain the error-corrected navigation message D; The supervision code p is the element in the navigation message verification information matrix P within the finite field GF(2). b The result is obtained by summing the columns below. The broadcast module is used to broadcast the error-corrected and encoded navigation message D.

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