Tiantong Beidou integrated communication device and method based on hybrid automatic retransmission

Abstract

The invention belongs to the field of Beidou navigation system short message communication and Tiantong communication, and relates to a Tiantong and Beidou integrated communication device and method based on hybrid automatic retransmission. According to the method, a sending end carries out fragmentation processing on original data, a Reed-Solomon FEC (RS FEC) method and an LDPC FEC method are used for coding the fragmented data at the same time, the data coded by the RS FEC are transmitted back to a receiving end through a Beidou short message link, and the data coded by the LDPC FEC are transmitted back to the receiving end through a Tiantong communication link. The receiving end corrects and analyzes the error code data in a verification and error correction decoding mode, and judges whether the two paths of data are normal or not and whether the data need to be transmitted back again or not by using a data verification function; and after the fragmented data is completely received, the receiving end can analyze the original data. According to the method, redundant backup and mutual verification of data are realized mainly by constructing a Beidou short message and Tiantong communication double-link data transmission mode, the bit error rate and packet loss rate of the data are reduced, and the reliability of data transmission is improved.

Description

Technical Field

[0001] The present invention belongs to the field of Beidou navigation system short message communication and Tiantong communication, and relates to a Tiantong-Beidou integrated communication device and method based on hybrid automatic retransmission. Background Art

[0002] In the maritime field, maintaining smooth communication between ships, boats, submarines and other carrier platforms and shore-based command centers and control rooms is crucial. Due to the distance from the continental shelf, two modes of communication are generally used: Beidou short message communication or Tiantong communication.

[0003] The BeiDou navigation system supports short message communication. Currently, this function can be implemented via geostationary satellites within public network coverage. However, due to technical limitations, data transmission capacity is limited, with frequency limited to minutes. Furthermore, data transmission is subject to significant latency, bit error rates, and packet loss. When data issues arise, traditional retransmission mechanisms are primarily relied upon, resulting in low efficiency and making them unsuitable for large data volumes and complex, latency-sensitive scenarios at sea.

[0004] The Tiantong-1 system is a mobile satellite communications system independently developed by my country. It boasts high bandwidth and large capacity, supporting high-speed voice and data communications. However, it also faces challenges such as signal interference, packet loss, and testing. In complex and volatile ocean environments, channel conditions are unstable, and single-link communication reliability is low.

[0005] The hybrid automatic repeat request mechanism primarily consists of forward error correction (FEC) and automatic repeat request (ARQ). By adding redundant information to the original data, the receiver can correct erroneous data after demodulation. When data errors are significant, automatic repeat requests can retransmit the erroneous data. This significantly improves transmission reliability and reduces retransmission times, holding great potential for multi-link joint communications.

[0006] Traditional transmission methods typically rely on single-link communication, which has poor anti-interference capabilities. Although Tiantong communication methods offer high bandwidth, packet loss still exists in complex environments. Existing communication systems fail to effectively integrate the dual-link capabilities of Beidou and Tiantong, and the data layer fails to fully utilize FEC+ARQ technology to improve data reliability. Consequently, there is a lack of communication methods suitable for integrated parallel transmission and joint error correction for Beidou and Tiantong. Summary of the Invention

[0007] This paper proposes a hybrid automatic retransmission-based integrated communication device and method for Tiantong and Beidou. This method primarily establishes a dual-link data transmission mode for Beidou short messages and Tiantong communications, enabling data redundancy and mutual verification, reducing the bit error rate and packet loss rate, and improving the reliability of transmitted data.

[0008] The technical solution adopted by the present invention is:

[0009] A hybrid automatic repeat request (HARQ)-based Tiantong Beidou integrated communication device includes a Tiantong Beidou encoding module at the transmitting end and a Tiantong Beidou decoding module at the receiving end; wherein the Tiantong Beidou encoding module includes a data processing module, a RS FEC encoding module, a LDPC FEC encoding module, a first Beidou short message module, and a first Tiantong communication module; and the Tiantong Beidou decoding module at the receiving end includes a second Beidou short message module, a second Tiantong communication module, a RS FEC decoding module, a LDPC FEC decoding module, and a data verification module.

[0010] The data processing module is used to slice the original data into fixed-size segments and send the sliced ​​data to the RS FEC encoding module and the LDPC FEC encoding module respectively; it is also used to resend the data of the corresponding segment to the RS FEC encoding module and the LDPC FEC encoding module after receiving NACK data;

[0011] The RS FEC encoding module is used to perform RS encoding on each received area data, send the RS-encoded data to the first Beidou short message module, and send ACK data or NACK data to the data processing module;

[0012] The first Beidou short message module is used to send the RS-encoded data to the Tiantong Beidou decoding module, and receive the ACK data or NACK data transmitted back by the Tiantong Beidou decoding module and send it to the RS FEC encoding module;

[0013] The LDPC FEC encoding module is used to perform LDPC encoding on the received data of each slice, send the LDPC-encoded data to the first communication module, and send ACK data or NACK data to the data processing module;

[0014] The Tiantong communication module is used to send the LDPC-encoded data to the Tiantong Beidou decoding module, and receive the ACK data or NACK data transmitted back by the Tiantong Beidou decoding module and send it to the LDPC FEC encoding module;

[0015] The second Beidou short message module is used to receive data transmitted by the first Beidou short message module, send the received data to the RS FEC decoding module, and send the ACK data or NACK data fed back by the data verification module to the first Beidou short message module;

[0016] The second communication module is used to receive data transmitted by the first communication module, send the received data to the LDPC FEC decoding module, and send the ACK data or NACK data fed back by the data verification module to the first communication module;

[0017] The RS FEC decoding module is used for RS decoding the data received by the second Beidou short message module, and sending the RS decoded data to the data checking module.

[0018] The LDPC FEC decoding module is used for LDPC decoding the data received by the second Tianxiang communication module, and sending the LDPC decoded data to the data checking module.

[0019] The data checking module is used for judging whether the two-way data of the same area is consistent, generating ACK data or NACK data according to the judgment result, the ACK data is used for indicating that the received data is normal, the NACK data is used for indicating that the received data is abnormal, and the ACK data or the NACK data is fed back to the second Beidou short message module and the second Tianxiang communication module, and is also used for storing the corresponding area data after the data checking is successful.

[0020] A Tianxiang-Beidou integrated communication method based on hybrid automatic repeat request, which is realized based on the above device, and the specific steps are as follows:

[0021] Step one: the Tianxiang-Beidou encoding module of the sending end carries out slicing processing on the received original data according to a fixed size;

[0022] Step two: each area data sliced in step one is subjected to RS encoding and LDPC encoding respectively;

[0023] Step three: the RS encoded and LDPC encoded data are respectively sent to the Tianxiang-Beidou decoding module of the receiving end;

[0024] Step four: the Tianxiang-Beidou decoding module of the receiving end simultaneously monitors the Beidou short message and the Tianxiang communication link, and respectively subjects the received data to RS decoding and LDPC decoding;

[0025] Step five: whether the two-way data of the same area is consistent is judged for the decoded data, and the ACK data is fed back to the Tianxiang-Beidou encoding module of the sending end for indicating that the received data is normal, and the NACK data is fed back for indicating that the received data is abnormal;

[0026] Step six: after receiving the NACK data, the Tianxiang-Beidou encoding module of the sending end retransmits the area data of which the checking fails.

[0027] Compared with the prior art, the above scheme has the following technical effects:

[0028] (1) The RS FEC encoding and decoding method is combined with the Beidou short message communication.

[0029] (2) The present invention combines the LDPC FEC encoding and decoding method with Tiantong communication. After the data layer is adjusted using the LDPC FEC encoding method, it can correct data errors caused by Tiantong channel transmission, thereby improving the stability and reliability of data transmission.

[0030] (3) The present invention segments the data transmitted by the Beidou short message and the Tiantong communication link, and adopts an automatic retransmission mechanism to retransmit the data in the error area. This avoids data errors and the waste of communication resources caused by retransmission of all data, and improves data utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural diagram of the Tiantong Beidou integrated communication device of the present invention.

[0032] Figure 2 This is a schematic diagram of the automatic retransmission mechanism of the present invention. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Figure 1 This is the structural diagram of the Tiantong Beidou integrated communication device of the present invention. The core concept of this invention is the mutual backup of Beidou short message communication and Tiantong communication. Data modulated by RS FEC is transmitted via Beidou short message; data modulated by LDPC FEC is transmitted via Tiantong communication. The receiving end decodes, corrects errors, and compares the data of the two links to determine the availability of the data; and determines whether to output retransmission, thereby reducing the data packet loss rate while further improving the data reliability. The details are as follows:

[0035] A hybrid automatic repeat request (HARQ)-based Tiantong Beidou integrated communication device includes a Tiantong Beidou encoding module at the transmitting end and a Tiantong Beidou decoding module at the receiving end; wherein the Tiantong Beidou encoding module includes a data processing module, a RS FEC encoding module, a LDPC FEC encoding module, a first Beidou short message module, and a first Tiantong communication module; and the Tiantong Beidou decoding module at the receiving end includes a second Beidou short message module, a second Tiantong communication module, a RS FEC decoding module, a LDPC FEC decoding module, and a data verification module.

[0036] The data processing module is used to slice the original data to be sent. It is assumed that each slice has 1024 bytes of data and a serial number is added before each slice to identify the order of the slice data. The size of the slice can be adaptively adjusted according to the amount of original data. After the slice is completed, the data is sent to the RS FEC encoding module and the LDPC FEC encoding module respectively. It is also used to resend the data of the corresponding slice to the RS FEC encoding module and the LDPC FEC encoding module after receiving NACK data.

[0037] The RS FEC encoding module is used to perform RS encoding on each received area data, send the RS-encoded data to the first Beidou short message module, and send ACK data or NACK data to the data processing module;

[0038] Because RS codes are particularly well-suited for correcting sudden errors, data can be broadcast via the Beidou navigation short message function. Reed-Solomon FEC encoding is a non-binary BCH (Bose-Chaudhuri-Hocquenghem) code widely used in digital communications and storage systems. By adding redundant symbols to the data, the receiver can automatically correct a certain number of errors, making it suitable for various scenarios requiring anti-interference and data recovery capabilities. The main logic of Reed-Solomon FEC encoding is as follows:

[0039] The data information group M after fragmentation is set as:

[0040] M=(m k ,m k-1 ,…,m1)

[0041] Its information polynomial m(x) is:

[0042] m(x)=m k x k-1 +m k-1 x k-2 +…+m2x+m1

[0043] The code word C of the RS code is:

[0044] C=(c n ,c n-1 ,…,c1)

[0045] Its codeword polynomial c(x) is:

[0046] c(x)=c n x n-1 +c n-1 x n-2 +…c2x+c1

[0047] The generating polynomial g(x) of the RS code is:

[0048] g(x)=(x-α)(x-α 2 )…(x-α 2t )

[0049] The encoding steps are:

[0050] Use x n-k Multiply by the code polynomial m(x).

[0051] Use m(x)x n-k Divide by g(x) and find the remainder r(x), which is:

[0052] r(x)=m(x)x n-k modg(x)

[0053] The code word c(x) is obtained by m(x) and r(x), that is:

[0054] c(x)=m(x)x n-k +r(x)

[0055] The codeword of the RS code after encoding is:

[0056] C=(c n ,c n-1 ,…,c1)

[0057] =(m k ,m k-1 ,…,m1,r n-k ,…r1)

[0058] The first k bits are information, and the last r=nk bits are check bits.

[0059] The LDPC FEC encoding module is used to perform LDPC encoding on the received data of each slice, send the LDPC-encoded data to the first communication module, and send ACK data or NACK data to the data processing module;

[0060] The LDPC code (Low-Density Parity-Check Code) is a linear block error-correcting code based on a sparse matrix. Its core concept is to achieve efficient error correction through a sparse check matrix and iterative decoding. It is mainly applicable to 5G communications, satellite communications, storage systems, etc., and uses the Tiantong communication segment for signal broadcasting. The encoding method is as follows:

[0061] LDPC code is a linear block code, and its encoding can be performed according to the encoding method of general block codes. That is, first, the Gaussian elimination method is used to transform the check matrix H into the following form:

[0062]

[0063] Among them, I n-k is the identity matrix of size (nk)×(nk), and Is a matrix of size (nk)×k, its transpose is P k×(n-k) , then the generator matrix G of the LDPC code is:

[0064] G=[P k×(n-k) |I k-k ]

[0065] Among them, I k-k is the identity matrix of size k×k, and P k×(n-k) Is a matrix of size k×(nk). Finally, it can be encoded by generating the matrix G;

[0066] c=u G=[u P k×(n-k) u]

[0067] Among them, u=(u1,u2,…,u k ) is the information bit, c=(c1,c2,…,c n ) is the generated codeword.

[0068] The first Beidou short message module is used to send the RS-encoded data to the Tiantong Beidou decoding module, and receive the ACK data or NACK data transmitted back by the Tiantong Beidou decoding module, and send it to the RS FEC encoding module.

[0069] The Tiantong communication module is used to send the LDPC-encoded data to the Tiantong Beidou decoding module, and receive the ACK data or NACK data transmitted back by the Tiantong Beidou decoding module and send it to the LDPC FEC encoding module.

[0070] The second Beidou short message module is used to receive data transmitted by the first Beidou short message module, send the received data to the RS FEC decoding module, and send the ACK data or NACK data fed back by the data verification module to the first Beidou short message module.

[0071] The second communication module is used to receive data transmitted by the first communication module, send the received data to the LDPC FEC decoding module, and send the ACK data or NACK data fed back by the data verification module to the first communication module.

[0072] The RS FEC decoding module is used to perform RS decoding on the data received by the second Beidou short message module and send the RS-decoded data to the data verification module;

[0073] For the decoding of Beidou RS, assume that the interference noise is e(x), i.e. error pattern; superimposed on c(x) to be transmitted to the receiving end together, assume that the received code word polynomial of the receiving end is r(x): r(x) = c(x) + e(x), wherein the expressions of c(x), r(x), e(x) are as follows:

[0074] c(x) = c0+ c1x + … + c n-1 x n-1

[0075] e(x) = e0+ e1x + … + e n-1 x n-1

[0076] r(x) = r0+ r1x + … + r n-1 x n-1

[0077] The basic principle of RS code decoding is: according to the received code word polynomial r(x), the error pattern e(x) is obtained, and then according to the formula r(x) = c(x) + e(x), e(x) is obtained, i.e. e(x) = r(x) - c(x);

[0078] RS code decoding mainly adopts time domain decoding, which calculates the error position according to the received code word, without conversion calculation, and is relatively easy to realize. The steps of time domain decoding are as follows: according to the received code word polynomial r(x), the adjoint s(x) and the key equation expression are obtained. Assume that y i is the value of the ith error, and x i is the position of the ith error.

[0079]

[0080] Wherein: i = 1, 2, …, 2t;

[0081] According to the adjoint s(x), the error position polynomial σ(x) and the error estimate polynomial ω(x) are obtained;

[0082] σ k+1 (x) = γ k σ k (x) - δ k+1 λ k (x)x

[0083] ω k+1 (x) = γ k ω k (x) - δ k+1 β k (x)x

[0084] Wherein δ k+1 can be expressed as λ k(x), β k (x),γ k are the coefficients that change during the iteration process of the above formula, and their initial values ​​are usually set to 1;

[0085] After the error position polynomial σ(x) is obtained, the error position x can be determined by finding the root of σ(x) i ;

[0086] According to the error location polynomial σ(x) and the error location x i Compute error value polynomial y i ;

[0087]

[0088] in, Expressed as the formal derivative of the error position polynomial;

[0089] According to the received codeword polynomial r(x) and the error value polynomial y i Find the information codeword and complete the decoding.

[0090] The LDPC FEC decoding module is used to perform LDPC decoding on the data received by the Tiantong communication module and send the LDPC decoded data to the data verification module;

[0091] For Beidou LDPC decoding, L is obtained from the channel reception value j , for all i and j, if L ij =1, then let

[0092]

[0093] In the above formula, σ is the standard deviation;

[0094] For all check nodes i (check equations), calculate the external information L transmitted from the check node to the variable node j→i ,Right now

[0095]

[0096] For all variable nodes j (codeword bits), calculate the external information L transmitted from the variable node to the check node j→i ,Right now

[0097]

[0098] For all j = 0, 1, ..., n-1, calculate:

[0099]

[0100] For all j=0,1,…,n-1, make a decision:

[0101]

[0102] The above steps are continuously performed until or the maximum number of iterations is reached, the decoding ends, and the code word is output

[0103] The data checking module is configured to determine whether two pieces of data in the same area are consistent, generate ACK data or NACK data according to the determination result, and feed back the ACK data or NACK data to the second Beidou short message module and the second Tianxiang communication module; the ACK data is used to indicate that the received data is normal, and the NACK data is used to indicate that the received data is abnormal; the data checking module is also configured to store the corresponding area data after the data checking is successful.

[0104] After receiving the data decoded and corrected by the Beidou short message and Tianxiang communication links, the data checking module first determines whether the two pieces of data are successfully checked, and if there is a checking failure, feeds back NACK incorrect reception information to the Tianxiang Beidou encoding module to reissue the area data of the checking failure; if both pieces of data are successfully checked and corrected, it is determined whether the data of the corresponding area of the two pieces of data are completely consistent, and when the data are consistent, the result is stored in the corresponding received area space; when the two pieces of data are inconsistent, NACK incorrect reception information is fed back to the Tianxiang Beidou encoding module to reissue the area data of the checking failure; when the checking, correction and two pieces of data are consistent, ACK correct reception information is returned to the sending end to retransmit the subsequent area data. After all the data are received completely, the received data are uniformly parsed to obtain complete data. Figure 2 as shown.

[0105] A Tianxiang Beidou integrated communication method based on hybrid automatic repeat, realized based on the above device, and the specific steps are as follows:

[0106] Step 1: The Tianxiang Beidou encoding module of the sending end divides the received original data into pieces according to a fixed size;

[0107] Step 2: Each piece of area data after the division in step 1 is respectively subjected to RS encoding and LDPC encoding;

[0108] Step 3: The data after the RS encoding and LDPC encoding are respectively sent to the Tianxiang Beidou decoding module of the receiving end;

[0109] Step 4: The Tianxiang Beidou decoding module of the receiving end simultaneously listens to the Beidou short message and Tianxiang communication links, and respectively subjects the received data to RS decoding and LDPC decoding;

[0110] Step 5: Determine whether the two data channels in the same area are consistent based on the decoded data, and feedback ACK data to the Tiantong Beidou encoding module at the sending end to indicate that the received data is normal, and feedback NACK data to indicate that the received data is abnormal;

[0111] Step 6: After receiving the NACK data, the Tiantong Beidou encoding module at the sending end resends the data of the area that failed the verification.

Claims

1. A Tiantong Beidou integrated communication device based on hybrid automatic retransmission, characterized in that: It includes a Tiantong Beidou encoding module at the sending end and a Tiantong Beidou decoding module at the receiving end; wherein the Tiantong Beidou encoding module includes a data processing module, an RS FEC encoding module, an LDPC FEC encoding module, a first Beidou short message module and a first Tiantong communication module; the Tiantong Beidou decoding module at the receiving end includes a second Beidou short message module, a second Tiantong communication module, an RS FEC decoding module, an LDPC FEC decoding module and a data verification module; The data processing module is used to slice the original data into fixed-size segments and send the sliced ​​data to the RS FEC encoding module and the LDPC FEC encoding module respectively; it is also used to resend the data of the corresponding segment to the RS FEC encoding module and the LDPC FEC encoding module after receiving NACK data; The RS FEC encoding module is used to perform RS encoding on each received area data, send the RS-encoded data to the first Beidou short message module, and send ACK data or NACK data to the data processing module; The first Beidou short message module is used to send the RS-encoded data to the Tiantong Beidou decoding module, and receive the ACK data or NACK data transmitted back by the Tiantong Beidou decoding module and send it to the RS FEC encoding module; The LDPC FEC encoding module is used to perform LDPC encoding on the received data of each slice, send the LDPC-encoded data to the first communication module, and send ACK data or NACK data to the data processing module; The Tiantong communication module is used to send the LDPC-encoded data to the Tiantong Beidou decoding module, and receive the ACK data or NACK data transmitted back by the Tiantong Beidou decoding module and send it to the LDPC FEC encoding module; The second Beidou short message module is used to receive data transmitted by the first Beidou short message module, send the received data to the RSFEC decoding module, and send the ACK data or NACK data fed back by the data verification module to the first Beidou short message module; The second communication module is used to receive data transmitted by the first communication module, send the received data to the LDPCFEC decoding module, and send the ACK data or NACK data fed back by the data verification module to the first communication module; The RS FEC decoding module is used to perform RS decoding on the data received by the second Beidou short message module and send the RS-decoded data to the data verification module; The LDPC FEC decoding module is used to perform LDPC decoding on the data received by the second communication module and send the LDPC decoded data to the data verification module; The data verification module is used to determine whether the two data in the same area are consistent, and generate ACK data or NACK data based on the judgment result. ACK data is used to indicate that the received data is normal, and NACK data is used to indicate that the received data is abnormal. The ACK data or NACK data is fed back to the second Beidou short message module and the second day communication module; it is also used to store the corresponding area data after the data verification is successful.

2. A Tiantong Beidou integrated communication method based on hybrid automatic retransmission, characterized in that: Based on the device described in claim 1, the specific steps are as follows: Step 1: The Tiantong Beidou encoding module at the sending end fragments the received raw data into fixed-size segments; Step 2: Perform RS encoding and LDPC encoding on each slice of data after sharding in step 1; Step 3: Send the RS-encoded and LDPC-encoded data to the Tiantong Beidou decoding module at the receiving end respectively; Step 4: The Tiantong Beidou decoding module at the receiving end monitors the Beidou short message and the Tiantong communication link at the same time, and performs RS decoding and LDPC decoding on the received data respectively; Step 5: Determine whether the two data channels in the same area are consistent based on the decoded data, and feedback ACK data to the Tiantong Beidou encoding module at the sending end to indicate that the received data is normal, and feedback NACK data to indicate that the received data is abnormal; Step 6: After receiving the NACK data, the Tiantong Beidou encoding module at the sending end resends the data of the area that failed the verification.

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