Method, device and system of self-adaptive dynamic forward error correction coding
A forward error correction coding and adaptive technology, applied in the field of adaptive dynamic forward error correction coding, can solve the problems of low efficiency and reliability of data transmission, inability to adapt to data, etc., achieve accurate and reliable data transmission, and improve data quality. The effect of transmission efficiency and the need to improve data transmission
Inactive Publication Date: 2010-02-17
NAT UNIV OF DEFENSE TECH
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Problems solved by technology
[0009] In the process of realizing the present invention, the inventor finds that the existing forward error correction technology has at least the following defects: in the existing adaptive FEC encoding method, a single FEC encoding algorithm is used, and generally the size of redundant data or whether Carry out FEC coding for control to adapt to the current network environment....
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View moreMethod used
In practical application, described encoding algorithm can be block code algorithm, convolution code algorithm, turbo code algorithm, low integration parity check code algorithm or RAID code algorithm etc., wherein, can adopt RS in the block code code (Reed-Solomon code), RAID code or XOR code, etc. Specifically, the sending device or the receiving device can establish a suitable coding algorithm between the two parties according to the needs of the current network status, so that when performing forward error correction coding according to the coding algorithm, the bandwidth occupied by data transmission is small and the link consumption is small. Low, and can effectively guarantee the accuracy of received data and improve the reliability of data transmission. At the same time, since the encoding algorithm is set according to the current network status, using the negotiated encoding algorithm for forward error correction can effectively reduce the network bandwidth occupied in data transmission and improve the efficiency of data transmission, thereby improving the overall Throughput of the communication system.
The embodiment of the present invention can be applied in the network that carries out message transmission based on forward error correction technology, specifically, the embodiment of the present invention can set up encoding between the sending device and the receiving device of the communication link of message transmission Negotiation mechanism, the sending device or the receiving device can actively initiate a coding negotiation request message to the other party according to its own network status, and establish a suitable coding algorithm between the two parties, so that when forward error correction coding is performed using the negotiated coding algorithm, the sending device The communication with the receiving device can be synchronized, which can effectively ensure the efficiency of data transmission while reducing the bit error rate in data transmission. Wherein, in order to facilitate description of the technical solution of the present invention, the embodiment of the present invention uses a communication link for packet transmission using a point-to-point protocol (Point to Point, PPP) as an example for description.
Therefore, in the embodiment of the present invention, the receiving device can initiate a negotiation request of a coding algorithm to the sending device according to its own network state, negotiate the coding algorithm adopted between the two parties, and use the negotiated coding algorithm to send data and data Receiving and performing cor...
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View moreAbstract
The invention discloses a method, a device and a system of self-adaptive dynamic forward error correction coding. The method comprises the following steps: launching coding consultation request information comprising a coding algorithm to a message transmission device on a communication link according to the current network status; receiving the coding consultation confirmation information that isreturned by the transmission device, and decoding messages received by the transmission device according to the coding algorithm. The device comprises a consultation transmission module and a receiving process module. In the technical schemes, a coding consultation mechanism can be established between the transmission device and a receiving device so as to establish the appropriate coding algorithm between the transmission device and the receiving device, therefore, the data transmission efficiency is improved while ensuring the data transmission reliability; and the invention can be suitablefor requirements of data transmission by adopting forward error correction coding under various network environments.
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[0036] The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.
[0037] The embodiment of the present invention can be applied to a network that performs message transmission based on forward error correction technology. Specifically, the embodiment of the present invention can establish an encoding negotiation mechanism between a sending device and a receiving device of a communication link for message transmission. The sending device or the receiving device can actively initiate coding negotiation request information to the other party according to its own network status, and establish a suitable coding algorithm between the two parties, so that when forward error correction coding is performed under the negotiated coding algorithm, the sending device and the receiving device The communication between them can be synchronized, which can effectively ensure the efficiency of data transmission while reducing the bit error rate in data transmission. In order to facilitate the description of the technical solution of the present invention, the embodiment of the present invention uses a point-to-point protocol (Point to Point, PPP) communication link for message transmission as an example for description.
[0038] The following first describes the communication process using the PPP protocol. figure 1 It is a schematic diagram of data transmission based on PPP protocol; figure 2 Schematic diagram of the negotiation phase of the PPP protocol. In low-speed communication links, such as radio stations, satellite communications, etc., message transmission generally uses PPP protocol for link control, data compression control, network layer protocol control and data encapsulation, which makes PPP protocol a low-speed link data The first choice for communication, and for high-speed links with high bit error rates or low bit error rates but high data transmission reliability requirements, such as optical fiber communication systems, PPP protocols are also widely used. Therefore, it is necessary to On the basis of the PPP protocol, the control of message error correction is extended. Among them, the negotiation process based on the PPP protocol is as follows:
[0039] (1) When the PPP link is activated (UP), it enters the Establish phase. Specifically, based on the PPP protocol standard, the link control protocol (Link Control Protocol, LCP) exchanges Configure messages to establish a connection When the Configure-Ack message is received, the negotiation interaction is completed and enters the LCP Open state, so that the LCP is in the Opened state.
[0040] (2) After the link establishment phase is over, enter the Authenticate phase. This authentication phase is optional. If the two parties have configured authentication options, the PPP protocol entity requires the other party to authenticate before exchanging network layer protocol messages. At this time, only after the two parties on the link pass each other's authentication can they enter the next stage of negotiation.
[0041] (3) After the authentication phase is over, enter the network (Network) layer protocol negotiation phase. According to the PPP protocol standard, the Compression Control Protocol (CCP) is first negotiated. CCP is responsible for configuring and enabling the PPP link at both ends. It can and close the data compression algorithm, and can also notify the failure of the compression/decompression mechanism in a reliable way. Among them, CCP negotiation is also optional.
[0042] Since most of the data transmission uses the IP protocol, after the completion of the CCP negotiation, an important part of the network layer protocol negotiation is to use the IP Control Protocol (IP Control Protocol, IPCP) to configure and use at both ends of the PPP link. The IP protocol module can be closed, and IPCP uses the same message exchange mechanism as LCP. The technical solution of the embodiment of the present invention can realize the negotiation of the forward error correction coding algorithm and the pre-adoption on the communication link using the PPP protocol. Data transmission is realized by error correction coding.
[0043] image 3 It is a flowchart of Embodiment 1 of an adaptive dynamic forward error correction coding method of the present invention. Such as image 3 As shown, the method of this embodiment includes the following steps:
[0044] Step 101: According to the current network state, initiate coding negotiation request information to a message sending device on the communication link, where the coding negotiation request information includes an encoding algorithm;
[0045] Step 102: Receive the coding negotiation confirmation information returned by the sending device, and perform decoding processing on the message received from the sending device according to the coding algorithm.
[0046] The technical solution of this embodiment can be applied to a communication system that uses forward error correction coding for data transmission. The receiving device in the data transmission can be based on its own network status, such as the actual bit error rate of the channel or the measured bit error rate. , Bandwidth, delay, availability, user needs, etc., determine the coding algorithm suitable for the current network state and meet the reliability of data transmission, and carry the coding algorithm in the coding negotiation request information and send it to the sending device in data transmission, Establish between the two parties to use a suitable coding algorithm to transmit data, so that when forward error correction data transmission is performed using the coding algorithm, the reliability of data transmission can be effectively guaranteed, the bit error rate of data transmission is reduced, and the bandwidth during data transmission is reduced Occupancy rate, improve data transmission efficiency. Specifically, when the receiving device sends the coding negotiation request information carrying the coding algorithm to the sending device, after receiving the coding negotiation request information, the sending device can respond according to its own conditions or network environment, such as whether the coding algorithm is supported, etc. Should the encoding negotiation request, if the encoding algorithm in the encoding negotiation request information is agreed, then the encoding negotiation confirmation message is returned to the receiving device, indicating that the encoding algorithm in the encoding negotiation request information is agreed to be used for data transmission, and then the sending device and the receiving device are The data can be processed according to the negotiated encoding algorithm to complete the sending and receiving of data, that is, the sending device can process and send the data according to the negotiated encoding algorithm, and the receiving device can send the data according to the encoding algorithm. The data received by the device is decoded accordingly.
[0047] In practical applications, when the receiving device decodes the received message incorrectly, it can initiate coding negotiation request information to the message sending device on the communication link according to the detected current network state, so as to communicate between the sending device and the receiving device. Establish appropriate coding algorithms to improve the accuracy and reliability of message decoding by the receiving device, and improve the efficiency of data transmission throughout the communication link.
[0048] In practical applications, the encoding algorithm can be a block code algorithm, a convolutional code algorithm, a turbo code algorithm, a low-integration parity check code algorithm or a RAID code algorithm. Among them, the block code can use RS code (Reed -Solomon code), RAID code or XOR code, etc. Specifically, the sending device or the receiving device can establish a suitable coding algorithm between the two parties according to the needs of the current network status, etc., so that the bandwidth occupied by data transmission when forward error correction coding is performed according to the coding algorithm is small, and the link consumption Low, and can effectively ensure the accuracy of received data, improve the reliability of data transmission. At the same time, since the encoding algorithm is set according to the current network status, the use of the negotiated encoding algorithm for forward error correction can effectively reduce the network bandwidth occupied in data transmission, improve the efficiency of data transmission, and improve the overall The throughput of the communication system.
[0049] In practical applications, when the sending device initiates the coding negotiation request information to the receiving device, and the sending device does not support the encoding algorithm carried by it, the sending device can return renegotiation request information to the receiving device. The renegotiation request information may include the suggestion of the sending device Using a new encoding algorithm, if the receiving device receives the re-negotiation request information returned by the sending device, it can re-initiate the encoding negotiation request information to the sending device according to the re-negotiation request information, and the re-initiated encoding negotiation request information It may include request information carrying the new encoding algorithm, so that the sending device and the receiving device can negotiate to determine an encoding algorithm suitable for both parties. At the same time, the receiving device can also select another suitable encoding algorithm to initiate encoding negotiation request information to the sending device according to its own needs, and establish an encoding algorithm suitable for both parties between the sending device and the receiving device.
[0050] Therefore, in the embodiment of the present invention, the receiving device can initiate a coding algorithm negotiation request to the sending device according to its own network status, negotiate the coding algorithm used between the two parties, and use the negotiated coding algorithm to respond to data transmission and data reception. The processing makes the data transmission based on the negotiated coding algorithm more accurate and reliable, and can effectively improve the data transmission efficiency of the entire communication link and communication system; the embodiment of the present invention can adopt different coding algorithms according to different network environments. Forward error correction coding can effectively improve the need for data transmission using forward error correction coding, reduce the error rate of data transmission, and improve the efficiency of data transmission.
[0051] Figure 4 It is a flowchart of the second embodiment of the adaptive dynamic forward error correction coding method of the present invention. The method of this embodiment may include the following steps:
[0052] Step 201: Count the number of times of decoding without errors when continuously decoding different received messages.
[0053] Step 202: Determine whether the number of times of decoding exceeds a preset number of times, if yes, execute step 203; otherwise, execute step 201.
[0054] Step 203: According to the current network state, initiate coding negotiation request information to the message sending device on the communication link.
[0055] Step 204: Receive the coding negotiation confirmation information returned by the sending device, and perform decoding processing on the message received from the sending device according to the coding algorithm.
[0056] In the embodiment of the present invention, the receiving device can count the number of consecutively correct decoding times for different received messages. When the number of consecutive decoding times exceeds the preset number, it indicates that the current network status is good. It is possible to allow the transmission of data with lower encoding strength. Therefore, when the number of correct decoding times for different message connections exceeds the preset number of times, the receiving device can set the encoding algorithm that is more suitable for the network state and send it to the sending device. Initiate a coding negotiation request, so that when forward error correction coding is performed under the new coding calculation, the coding strength is reduced, so that less network bandwidth is occupied during data transmission, and the efficiency of data transmission is improved. At the same time, the data transmission can be guaranteed. Accuracy and reliability.
[0057] It can be seen that the embodiment of the present invention can re-send the coding negotiation request information according to the actual needs of the receiving device when the network is in good condition, so as to establish the use of a new coding algorithm for forward error correction coding, which can prevent data from being in for a long time. The stronger coding strength reduces the efficiency of data transmission, can effectively improve the efficiency of data transmission of the entire communication link, and improve the throughput of the entire communication system.
[0058] In the foregoing embodiments, when the receiving device initiates the encoding negotiation request information to the sending device, the encoding negotiation request information may also include encoding parameters corresponding to the encoding algorithm to confirm the size of the encoded redundant data. Of course, according to actual conditions In order to ensure the accuracy and reliability of data transmission, and the efficiency of data transmission, it is also possible to negotiate only the appropriate coding parameters used in the coding between the sending device and the receiving device when performing coding negotiation.
[0059] In the foregoing embodiments, the sending device may also initiate the coding negotiation request information. In this case, the forward error correction coding algorithm used between the sending device and the receiving device is generally established before data transmission, so that when the data starts to be transmitted That is, it has a better data transmission effect.
[0060] In order to have a better understanding of the technical solution of the present invention, the implementation of the encoding algorithm negotiation between the sending device and the receiving device on the PPP link will be described below.
[0061] In practical applications, the coding algorithm negotiation between the sending device and the receiving device in the embodiment of the present invention can be realized on the communication link using the PPP protocol, and the FEC error correction algorithm can be configured on the sending device and the receiving device of the PPP link. Protocol (FEC Control Protocol, FCP), FCP can be used to identify the encoding algorithm used for error correction encoding and decoding. Therefore, the FCP can be used to negotiate the encoding used between the sending device and the receiving device for forward error correction encoding and data transmission. Algorithms, specifically, the receiving device or the sending device can negotiate a suitable encoding algorithm with the other end of the data transmission according to the needs of its own network, so as to improve the efficiency of data transmission and the reliability of data transmission. Among them, FCP is a network layer negotiation protocol, FCP can use the same message exchange mechanism as LCP, and FCP messages can only be exchanged when PPP reaches the network layer protocol stage.
[0062] The following describes the FCP protocol in order to have a better understanding of it. Specifically, the FCP protocol and the LCP are the same as the LCP except for the following differences:
[0063] (1) Different frame formats.
[0064] The frame format of the FCP message is different from the frame format used by the LCP during the link establishment phase negotiation. Specifically, the values of some of the fields have been modified. The following descriptions of the differences in the fields can be seen.
[0065] (2) The data link protocol domain is different.
[0066] An FCP message is encapsulated in the PPP information field. At this time, the type number of the PPP protocol field is 803D, which indicates that it corresponds to FCP.
[0067] (3) The Code Field is different.
[0068] In addition to codes 1-7, namely Configure-Request, Configure-Ack, Configure-Nak, Configure-Reject, Terminate-Request, Terminate-Ack and Code-Reject, two additional codes 14 and 15 have been added to FCP, namely Reset-Request and Reset-Ack. In addition, other codes should be treated as unknown and respond to Code-Rejects.
[0069] (4) The timeout operation is different.
[0070] The FCP message can only be exchanged when the PPP has reached the network layer protocol stage. When it is implemented, it should first wait for the authentication and link quality determination (Link Quality Determination) to start after the Configure-Ack or other response timeout operations, specific implementation It is recommended that only when the user intervenes or waits for a configurable time before giving up and continuing to wait for a response.
[0071] (5) Configuration Option Types are different.
[0072] The FCP protocol has its own configuration options, which will be introduced later.
[0073] (6) Sending Fec-coded Datagrams is different.
[0074] Before any FEC encoded message can communicate, PPP must reach the network layer protocol stage, and FCP must be in the Opend state.
[0075] One or more FEC encoded messages are encapsulated in the PPP information field, and the hexadecimal value of the PPP protocol field type is 003D, which corresponds to the FEC encoded message. Each FEC encoding algorithm can use different mechanisms to indicate that one or more unencoded messages are included in a Data Link Layer frame to confirm whether the previous decoded message is correct , Or for encoding synchronization, etc.
[0076] Only one main FEC encoding algorithm can be used in each direction of the PPP link at a time. The specific algorithm used and the corresponding encoding algorithm parameters are negotiated between message interactions. The PPP protocol field of the FEC encoded message indicates The frame is FEC encoded, but it does not indicate which FEC encoding algorithm and related encoding algorithm parameters are used.
[0077] The maximum length of the FEC encoded message transmitted on the PPP link is the same as the maximum length of the information field (Information field) of the PPP encapsulated message, and longer messages can be sent without encoding, such as standard formats Or, if the FEC encoding algorithm supports it, multiple messages can be sent. In this agreement, normal messages that do not use FEC encoding can be encapsulated and sent using a PPP frame with a protocol domain type of 003F to facilitate FEC encoding synchronization or other needs.
[0078] Since the FEC encoding algorithm can judge whether the received data is correct from the encoding information in the message, the FEC algorithm does not require that the underlying PPP data transmission is reliable, but the FEC encoding algorithm must have a mechanism to determine the encoded message Whether the encoding and decoding are synchronized.
[0079] The message format and basic mechanism of FCP are the same as those defined in the LCP protocol. The latest values of the FCP code field (Code field) in FCP are 003D and 003F, which are used for message sending and receiving, and the following are added to FCP The FCP code domain value:
[0080] 14Reset-Request
[0081] 15Reset-Ack
[0082] In order to provide a mechanism to indicate the failure of decoding in one direction of the communication link without affecting the traffic in the other direction, FCP provides Reset-Request and Reset-Ack codes. The failure of decoding can be achieved by the number of error data blocks during decoding is greater than the current The coding error correction ability can be judged, and the erroneous data block can be judged by the CRC check value attached after the data block.
[0083] If the FCP implementation wants to indicate that the decoding is invalid, it can send an FCP message with a code field of 14, namely Reset-Request, and fill in any desired data in the data field. After sending the Reset-Request, any received FEC-encoded packets should be discarded and another Reset-Request should be sent until a legal Reset-Ack is received. After receiving the Reset-Request, the sender’s FEC encoder returns to its initial state, that is, re-initializes the relevant parameters of the encoding algorithm. At this time, FEC must send an FEC message with a code field of 15, namely Reset-Ack, as a response, with its id The field, that is, the identifier field is the same as the id in the Reset-Request, and the data field is filled with any desired data. If a Reset-Request or Reset-Ack FCP message is received, the receiver should determine whether there is a fatal error in the local decoding. If a fatal error occurs, the FCP should be closed and the FCP message with the code field Terminate-Request should be sent to the other party. If a non-fatal error occurs, you can send a Configure-Request message to request the other party to return to the link establishment phase.
[0084] Figure 5 It is a schematic diagram of the encoding format of Reset-Request and Reset-Ack messages in FCP. Specifically, such as Figure 5 As shown, the corresponding message fields in the Reset-Request and Reset-Ack message encoding formats are transmitted from left to right, where,
[0085] In the code (Code), 14 means Reset-Request, 15 means Reset-Ack; during transmission, the id field must be changed when the content of the data field changes and a legal reply to the previous request (Request) is received. , That is, the Identifier field. When a Reset-Request message is received, the id field of the Reset-Request should be copied to the id field of the Reset-Ack message; the Data field is 0 or more bytes , Contains uninterpretable data to the sender, the data can contain any binary value, the length can be any length, from 0 to the MRU value of the other party -4.
[0086] The following describes the FCP configuration options. The FCP configuration option allows negotiation of compression algorithms and corresponding algorithm parameters. FCP uses the same configuration option format as the LCP protocol, but the options are different. The configuration option in FCP indicates the encoding algorithm used by the receiving device. The receiving device is willing or able to decode the data sent by the sending device according to the encoding algorithm. Assuming that the system can provide multiple algorithms, one of them can be negotiated and used. Since the sending and receiving parties of data may not be able to agree on all error correction algorithms (ie forward error correction coding algorithms), error correction algorithms may not be used at this time. Therefore, the communication link must reach an agreement without error correction. When LCP negotiates again, the FCP state must be renegotiated. In addition, since many users can use their own proprietary algorithms, users can also set a number according to their own code, and this number is different from the number given by the FCP protocol later, that is, users can also customize the algorithm and Corresponding number in FCP.
[0087] In actual applications, if the configuration option cannot be recognized by the receiver, configure-reject is sent. If all the receivers of the FEC encoding algorithm are not recognized, it indicates that FEC encoding cannot be used in this direction of the communication link. If the configuration option can be recognized by the receiver, but because the option value cannot be accepted by the receiver, or there is no option parameter, a Configure-NAK must be sent, which contains the modified option value, and the Configure-NAK must contain only acceptable options . When the sender receives a Configure-NAK, it should send a new Configure-Request, in which the option value is modified to the value desired by the receiver, so that a consensus encoding algorithm can be reached between the two parties.
[0088] Specifically, the FCP option type field can support the following option values:
[0089] FCP Option FEC Coding Type
[0090] 2 XOR
[0091] 3 RS
[0092] 4 RAID6-Like
[0093] 5 turbo yards
[0094] 6 Convolutional codes
[0095] 7 Low integration parity check code
[0096] 8-15 unassigned code
[0097] 255 Reserved
[0098] The coding algorithms corresponding to option values 1 to 7 in the above option type fields are all commonly used coding algorithms. Unassigned codes can be user-specific FEC coding algorithms, and the proprietary FEC coding algorithms may not require license authorization. The corresponding option value can be defined by the user.
[0099] In order to have a better understanding of the application of the encoding algorithm in the FCP in the embodiment of the present invention, the encoding methods of the XOR and RS encoding algorithms are described below:
[0100] (1) XOR encoding algorithm.
[0101] Image 6 It is a schematic diagram of the message format of the XOR encoding algorithm in FCP. Specifically, such as Image 6 As shown, this configuration option provides a way to negotiate the use of the XOR encoding algorithm. XOR is a typical block code. Since a segment can only contain one error correction block (ie, redundant code), An error correction can only correct the errors of one block in a section. Therefore, its error correction capability depends entirely on the number of blocks in the section, that is, the number of original data blocks corresponding to an error correction block. For XOR encoding, the encoding parameters include the original data block size (BS) and the number of segments (segment size, SS), and the unit is byte. The number of blocks in a segment is BS/SS. In addition, for each original data block, one or more check bytes are required to verify the correctness of the data block after receiving. The check method is CRC8 or CRC16, that is, an 8-bit or 16-bit cyclic redundancy check.
[0102] The following describes each message field in the message format of the XOR encoding algorithm:
[0103] The Type value is 2, which means that the XOR coding algorithm is used; the Length value is 8; BS represents the size of each code block, in bytes, and a CRC is added to the end of the block; SS represents the size of each code segment, in units Is a byte, and an XOR-encoded error correction block is added to the end of the segment, where SS is 0, which means that the entire data is regarded as a segment. SS is generally an integer multiple of BS. If it is a non-integer multiple, the last one at the end of the segment The block should be filled with 0 before encoding; CRC bits represents the number of CRC check bits after each encoding block, and its value is usually 8 (ie 1 byte) or 16 (ie 2 bytes), using CRC8 Or CRC16 check.
[0104] (2) RS coding algorithm.
[0105] Figure 7 It is a schematic diagram of the message format of the RS encoding algorithm in FCP. Specifically, such as Figure 7 As shown, this configuration option provides a way to negotiate the use of RS coding algorithm. Like XOR code, RS code is also a typical block code, but the error correction capability of RS code is much higher than that of XOR code. According to the ITU-T recommendation of the Telecommunication Union, the RS coding format can be expressed as (n, k, d), where n=2 m -1, d=n-k+1, m is a positive integer, and the RS coding algorithm can correct t=(d-1)/2 m-ary code errors. Generally speaking, m=8, that is, during normal RS8 encoding, it can correct a burst code error with a length of t bytes. Since it is a block code, the length of the encoded data block and the segment length must also be explained , This is the same as XOR encoding, the data block check also uses CRC check.
[0106] The following describes each message field in the message format of the RS encoding algorithm:
[0107] The Type value is 3, which means that the RS coding algorithm is used; the corresponding value of Length is 14; Coded size(n) is used to indicate the value range of the current coding, that is, the number of all symbols, because RS coding is based on a finite field From the above, the finite field, the Galois field, refers to a field with a finite number of elements. The number of elements in the field is called the order of the field. By using GF(q), RS coded symbols are all in GF In the (q) domain, its length is n=q-1; the value K corresponding to Data size(k) represents the number of original information symbols before encoding; the value d corresponding to Minimum Distance(d) represents the minimum Hamming distance of RS encoding , D should satisfy d=n-k+1=2t+1, t refers to the number of errors that can be corrected, so in actual transmission, if the d value received by the receiver cannot meet the above conditions, the message should be discarded by default ; BS represents the size of each code block, the unit is byte, the end of the block is appended with a CRC check; SS represents the size of each code segment, the unit is byte, according to the adopted code, the end of the segment is appended one or more RS error correction block, SS is 0 means that the whole data is regarded as a segment, SS is generally an integer multiple of BS, if it is a non-integer multiple, the end of the segment should be filled with 0 before encoding; CRC bits represent each The number of bits of the CRC check after the encoding block is usually 8 (that is, 1 byte) or 16 (that is, 2 bytes).
[0108] Figure 8 It is a schematic diagram of the working stage of encoding algorithm negotiation through FCP in an embodiment of the present invention. Specifically, when the sending device and the receiving device communicate using the PPP protocol, and the above-mentioned FCP is used to negotiate the encoding algorithm of the sending and receiving parties, the working stage can be as follows Figure 8 As shown, the entire PPP protocol includes link control negotiation, password authentication negotiation, compression control negotiation, FEC control negotiation, and IP control negotiation. Among them, the type of control message interaction can range from 1 to 15, where 14 is Reset-Request , 15 is Reset-Ack. It can be seen that in the PPP protocol communication process, in addition to the original link control negotiation, password authentication negotiation, compression control negotiation, and IP control negotiation, the receiving device and the sending device can also be reached through FEC control negotiation, that is, FCP negotiation Consistency between the encoding algorithms. It can be seen that the synchronization of the coding algorithm adopted between the sending device and the receiving device can be realized through FCP negotiation, which can effectively ensure the accuracy and reliability of data transmission.
[0109] In addition, the embodiment of the present invention also proposes a method for determining the error correction capability for data communication in the network, which is the optimal segment length of the encoded original data under the assumption that the probability p of data error in network data transmission is determined Is n, and the length of the error correction coding part is k.
[0110] The receiving device can calculate the probability of data message loss according to the data transmission situation as p, and the total length of the message after encoding the data is n+k, then from the theory of probability, the receiving device has i The probability of each error is P i :
[0111] P i = C n + k i p i ( 1 - p ) n + k - i - - - ( 1 )
[0112] After FEC error correction and repair, the actual packet error probability can be approximately calculated with the following formula:
[0113] P ′ = ( n + k ) p - X i = 1 k P i ( n + k ) = ( n + k ) p - X i = 1 k C n + k i p i ( 1 - p ) n + k - i ( n + k ) = p - X i = 1 k C n + k i p i ( 1 - p ) n + k - i ( n + k ) - - - ( 2 )
[0114] From formula (2), it can be seen that the probability of the receiving device being completely received correctly is determined by the probability p of the data message transmitted by the network and the message length n+k. Since k is a constant, the optimal message length is determined by n . However, formula (2) is not convenient to be converted into an analytical expression. In this embodiment, an approximate method is used to determine the value of n.
[0115] Since the number of errors i after decoding of each message obeys the binomial distribution with a parameter of n+k, according to probability theory, the mathematical expectation of the number of errors i of the message is:
[0116] E(i)=(n+k)p (3)
[0117] Therefore, the original data length n corresponding to the number of errors in each message less than k should be:
[0118] ( n + k ) p ≤ k ⇒ n ≤ k p - k = k ( 1 p - 1 ) - - - ( 4 )
[0119] Among them, n can only be an integer, so:
[0120]
[0121] In actual use, the original data length n can be obtained according to formula (5), and n can be appropriately modified according to the specific needs of the user for the actual data loss probability (ie packet loss rate), and the FCP protocol can be used by both the sender and the receiver Negotiate the most suitable block size and segment size to obtain a suitable coding algorithm and corresponding coding parameters.
[0122] In fact, according to formula (1), there can be:
[0123] P i P i + 1 = C n + k i p i ( 1 - p ) n + k - i C n + k i + 1 p i + 1 ( 1 - p ) n + k - i - 1 = i ! ( n + k - i ) ! ( n + k ) ! ( 1 - p ) ( i + 1 ) ! ( n + k - i - 1 ) ! ( n + k ) ! p = ( n + k - i ) ( i + 1 ) ( 1 p - 1 )
[0124] Therefore, when p is small and n is appropriate, it is clear that p ip i+1 Therefore, the message error probability tends to decrease rapidly as errors increase.
[0125] Picture 9 It is a schematic structural diagram of Embodiment 1 of an adaptive dynamic forward error correction coding apparatus of the present invention. Such as Picture 9 As shown, the device of this embodiment includes a negotiation sending module 11 and a receiving processing module 12, where:
[0126] The negotiation sending module 11 is configured to initiate encoding negotiation request information to the message sending device on the communication link according to the current network state, where the encoding negotiation request information includes an encoding algorithm;
[0127] The receiving processing module 12 is configured to receive the encoding negotiation confirmation information returned by the sending device, and to decode the message received from the sending device according to the encoding algorithm.
[0128] In the embodiment of the present invention, a negotiation mechanism can be established between the sending device and the receiving device, and the coding algorithm used between the sending device and the receiving device can be negotiated according to the network status. Specifically, the functions of each module in the embodiment of the present invention can be adopted by the above-mentioned present invention. The steps in the first embodiment of the adaptive dynamic forward error correction coding method are implemented, which can produce the same technical effects as the method embodiments, and will not be repeated here.
[0129] Picture 10 It is a schematic structural diagram of Embodiment 2 of an adaptive dynamic forward error correction coding apparatus of the present invention. Specifically, such as Picture 10 As shown, the present implementation device includes a negotiation sending module 11, a receiving processing module 12, a decoding frequency counting module 15 and a judgment module 16, wherein,
[0130] The decoding times counting module 15 is used to count the number of times of decoding without errors when the received different messages are continuously decoded;
[0131] The judging module 16 is configured to judge whether the number of decoding times exceeds a preset number of times, and transmit the judgment result to the negotiation sending module 11;
[0132] The negotiation sending module 11 is configured to initiate encoding negotiation request information to the message sending device on the communication link when the determination result of the determination module 16 is that the number of decoding times exceeds the preset number of times, where the encoding negotiation request information includes Coding algorithm
[0133] The receiving processing module 12 is configured to receive the encoding negotiation confirmation information returned by the sending device, and to decode the message received from the sending device according to the encoding algorithm.
[0134] The embodiment of the present invention can be based on the actual needs of the receiving device in the data transmission of the communication link. When the network is in good condition, the coding negotiation can be established between the sending device and the receiving device to adopt a new coding algorithm to achieve forward error Error coding, the specific implementation process can be achieved by the steps in the second embodiment of the adaptive dynamic forward error correction coding method of the present invention, which can produce the same technical effect as the method embodiment, and will not be repeated here.
[0135] Picture 11 It is a schematic structural diagram of an embodiment of an adaptive dynamic forward error correction coding system of the present invention. Specifically, such as Picture 11 As shown, the system of this embodiment includes a receiving device 1 and a sending device 2, where:
[0136] The receiving device 1 is configured to initiate coding negotiation request information to a message sending device on the communication link according to the current network state, the coding negotiation request information includes an encoding algorithm; and receiving the coding negotiation confirmation information returned by the sending device , And decode the message received from the sending device according to the encoding algorithm;
[0137] The sending device 2 is configured to receive the coding algorithm negotiation request information sent by the receiving device, and return negotiation confirmation information according to its own state.
[0138] In the embodiment of the present invention, the sending device and the receiving device can perform coding negotiation to establish a suitable forward error correction coding algorithm between the two parties to adapt to data transmission under the current network environment and improve the efficiency of data transmission. The device may include the modules in the embodiment of the adaptive dynamic forward error correction coding apparatus of the present invention, which can initiate a coding negotiation request to the sending device according to the current network state.
[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: Modifications or equivalent replacements can be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
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