CN101777963B - Method for coding and decoding at frame level on the basis of feedback mechanism - Google Patents

该发明属于通信领域信息传输技术中的信道编码与译码的方法。包括发射端的组帧、成帧处理、帧编码处理和发送、加入帧识别号、信号处理及发送；以及接收端的信号接收及常规信号处理、帧的检测、译码处理及将系统帧送入信宿。该发明在发射端只对错误的帧进行编码大大地降低了参与编码的帧数量、以及编码和译码的复杂度，并通过反馈机制根据接收端反馈回来的接收情况再进行下一步的编码、以提高传输效率；接收端能够将错误帧通过简单的译码方法恢复；又有效地提高了传输容量；由于编码允许很多错误帧参与、且不要求错误帧是连续的，又提高了其纠错能力。因而具有编码和译码的复杂度低，纠错能力强，系统的传输容量大、传输效率及可靠性高等特点。The invention belongs to the method of channel coding and decoding in information transmission technology in the communication field. Including framing, framing processing, frame encoding processing and sending, adding frame identification number, signal processing and sending at the transmitting end; and signal receiving and conventional signal processing at the receiving end, frame detection, decoding processing and sending system frames to the destination . The invention encodes only the wrong frames at the transmitting end, which greatly reduces the number of frames involved in encoding and the complexity of encoding and decoding, and performs the next step of encoding and decoding according to the receiving situation fed back by the receiving end through the feedback mechanism. In order to improve the transmission efficiency; the receiving end can restore the error frame through a simple decoding method; and effectively improve the transmission capacity; because the encoding allows many error frames to participate and does not require the error frames to be continuous, it also improves its error correction. ability. Therefore, it has the characteristics of low encoding and decoding complexity, strong error correction ability, large transmission capacity of the system, high transmission efficiency and reliability.

A kind of frame grade encoding and interpretation method based on feedback model

Technical field

The invention belongs to data (information) transmission technology in the communications field, particularly the frame grade encoding based on feedback model and the interpretation method in a kind of method of chnnel coding for reduction transmission error rate and decoding.

Background technology

Along with the development of the communication technology, the requirement of transmission capacity and distance is also in continuous growth.In data communication; signal often can be because the impact that is subject to noise, decline or other reasons produces mistake; in order to ensure communication quality and efficiency; must be controlled and correct these mistakes, common error-control technique mainly comprises that forward error correction (FEC) and feedback retransmit technology such as (ARQ).Forward error correction is a kind of very effective method, common forward error correction, is chnnel coding, and Read-Solomon (Reed-Solomon) code, convolution code, turbo code and low density parity check code (LDPC) etc. are arranged.Forward error correction, particularly recent fast-developing turbo code and LDPC code, be characterized in one-way transmission, do not need feedback, can automatically correct a mistake according to the regularity of code, and error correction is rapid, and error correcting capability is very strong; But the volume of forward error correction, decoding architecture complexity, efficiency is low, generally only is used in communication physical layer as the bit-level error correction in frame.

Owing to only adopting forward error correction to be difficult to guarantee that the frame through decoding must be correct, thereby generally on the upper strata of communication system, also to adopt other error correcting technique of frame level further to improve the reliability of transmission, and wherein modal be also that the simplest frame rank error correcting technique is exactly the ARQ technology.The characteristics of this technology be simple in structure, need feedback channel, but need in frame, not increase very long redundant information in transmission, and as long as increase very short error detection sequence, receiving terminal judges that according to this sequence whether this frame is correct, if correctly, receive, otherwise abandon this frame, and require transmitting terminal to retransmit this frame by based on feedback link.And the other class that recent development goes out is based on the frame level, other is called as the communication technology of " without speed " code and network code; Wherein, common no-rate codes has LT code, Raptor code and binary system to determine no-rate codes etc., the characteristics of this type of no-rate codes are exactly " without speed " property, when using no-rate codes as error control, transmitting terminal constantly sends other frame after coding of frame level, and receiving terminal carries out decoding to the frame of receiving, after receiving terminal is received abundant frame, just can recover the prime information frame fully, and then feed back a termination signal to transmitting terminal, transmitting terminal just stops continuing to send; Whole transmitting procedure, except termination signal, receiving terminal does not need to feed back to transmitting terminal other information again, such as the packet drop of packets of information, and wants the regular transmitting terminal that feeds back to unlike the ARQ technology; Also just because of without in the speed rates process not by the reception condition immediate feedback to transmitter, thereby it is low often just to feed back retransmission technique aspect efficiency of transmission.And network code both can be for Multicast Channel to have improved the transmission capacity of whole system, also can be for general transmission, particularly under the multicast and broadcast channel using network code when a kind of error correcting technique improves the reliability of transmission, require system that feedback channel is arranged, this error correcting technique is in the situation that there is feedback channel, when receiving terminal occurs that because of reception information mistake requires to retransmit, transmitting terminal no longer directly retransmits the information frame of makeing mistakes, but first some information frames is carried out being retransmitted after other coding of frame level again; And, at receiving terminal, each receiver can, according to own frame loss condition, process by simple XOR the correct frame that finds oneself to need from the coded frame retransmitted.

Be ARQ technology, no-rate codes or network coding technique no matter above-mentioned, be all to carry out decoding for through CRC, detecting correct frame when decoding, and erroneous frame is directly discarded.And in fact, in the frame be dropped, the bit number of most of frame mistake is considerably less, if can be at receiving terminal by technical finesse targetedly, be about to wrong particular location and find out and correct, make it become correct frame, thereby just can effectively improve the transmittability of channel, comprise the reliability of transmission and the efficiency of transmission.The frame folding grown up on the ARQ technical foundation, utilize this principle, at receiving terminal, erroneous frame is recovered to the prime information frame by detection exactly, thereby this technology also requires system that based on feedback link is provided; But different from ARQ is, this technology does not discard the frame of error of transmission for the first time, but preserve, if retransmit for the second time identical frame, mistake appears again, by the contrast of bit value diverse location in two erroneous frame, determine the errors present that it is possible, once find the position of makeing mistakes, just can recover by the way of poor search the prime information frame.But adopt the precondition of frame folding: the one, wrong bit number can not be too many, and not so the complexity of poor search is too high, but otherwise may cause the error detection failure because of the error detection scope that exceeds frame detection sequence; Two is that the error bit of two frames can not be positioned at same position, otherwise will occur undetected and can not find out its error bit, thereby also just can't recover the prime information frame; Its three, when continuous errors only occurs in this technology in frame transmission just effectively.Thereby the defect such as this technology exists again reducing the transmission error rate, the usefulness that improves transmission reliability and hoist capacity is poor, and range of application is narrow.

Summary of the invention

The objective of the invention is on basis of background technology, improve a kind of frame grade encoding and interpretation method based on feedback model of design, function with strengthening channel volume, decoding, improve ability, the reduction transmission error rate in transmission, erroneous frame being controlled and corrected, effectively reliability and the capacity of elevator system transmission, guarantee the purposes such as communication quality and efficiency.

Solution of the present invention is the angle from frame grade encoding, in feedback, retransmit on the basis of (ARQ) and frame folding, cataloged procedure is divided into to two stages, first stage is system coding, this stage, encoder is only to see off sent to the frame come by last module again, be left intact, second stage is the redundancy encoding stage, the frame number fed back according to each receiving terminal at this stage coding device, they are carried out to the XOR processing according to bit to bit, obtain a redundant frame, and deliver to next module; Decode procedure is: the system-frame of receiving is preserved, often receive that a redundant frame participates in the frame number of coding according to redundant frame, corresponding system-frame is taken out from frame memory, and system-frame and the corresponding redundant frame of receiving thereof are carried out to the XOR processing, obtain an errors present indicator sequence; If the bit number that participate in system-frame that XOR processes, does not have the even number frame to make mistakes and make mistakes at identical bit is limited at every turn, adopt poor searching class method to be recovered, to the system-frame that can't meet this condition, again pass redundant frame, the content of redundant frame is decided by feedback procedure; In order to make the efficiency of transmission maximum, the processing procedure of feedback is random half or 1 system-frame of taking out from current all system-frame of failing to recover decode procedure, and its frame number is sent to transmitter from feedback channel, then transmitting terminal produces a new redundant frame according to these frames again, then sends the decoding that decoder carries out a new round to; Thereby realize its purpose.Therefore, the inventive method comprises transmitting terminal and receiving terminal bi-level treatment, wherein:

A. the transmitting terminal treatment step is:

A. framing: the initial data that signal source is sent is sent into the framing processing module, is carried out framing, and framing turns and adds the verification sequence module after processing;

B. framing processing: the signal after a step framing is processed is sent into and added the verification sequence module and make framing and process, for each frame inserts Frame Check Sequence, with the examination to this frame for receiving terminal;

C. frame coding is processed and is sent: after the signal of b step framing processing is sent into the frame coding module, preserve, more continuously each system-frame is sent into to the d step according to the order of first in first out; Then accordingly these system-frame and verification sequence thereof carried out to the XOR processing, obtain a new redundant frame according to each frame number information (set of one or more system-frame frame numbers) that receiving terminal feeds back constantly, also send it to the d step, until only receive when receiving terminal sends the confirmation signal received;

D. add the incoming frame identifier: the information after the frame coding module is processed is sent into and added the frame number processing module, add respectively the identifier of this frame in each system-frame and redundant frame, then deliver to the normal signal processing module;

E. signal is processed and is sent: the information that add through the d step after the frame identifier is processed is sent into to signal processing module, signal is carried out to routine interweaves, modulation treatment, then send into channel and send;

B. the receiving terminal treatment step is:

A. signal receives and conventional treatment: the transmitting terminal signal of receiving is sent into to signal processing module, after carrying out conventional demodulation, deinterleaving and processing, send into next step;

B. the Check processing of frame: the signal after the demodulation of a step, deinterleaving are processed is sent into to the frame detection module, at first remove its frame number and according to former frame number, this frame is kept in corresponding frame memory from each system-frame of receiving, then according to Frame Check Sequence detect this system-frame to mistake, and its result is kept in the relevant position of frame quality buffer; And directly send into decoder after the redundant frame of receiving is removed to its frame number, carry out the decoding processing;

C. decoding is processed: the redundant frame after frame detector is processed is sent into decoder, and according to following steps, system-frame is recovered, at first obtain the redundant frame supplementary set, then obtain the errors present indicator sequence, then recovery system frame, if system-frame is still arranged not to be recovered, take out half or 1 at random from current all system-frame of failing to recover, and their frame number is sent to transmitting terminal from feedback channel, after obtaining new redundant frame, continue decoding, until all system-frame are all correctly recovered, send again the confirmation signal received from feedback channel to transmitting terminal,

D. the system-frame in frame memory is sent into to the receiving system stay of two nights.

Above-mentioned Frame Check Sequence is cyclic redundancy check (CRC) (CRC) sequence and detection method thereof.

In the step c processed at receiving terminal: described redundant frame supplementary set, its method is by upper one, redundant frame, a upper moment redundant frame supplementary set and current time redundant frame are carried out the XOR processing constantly; During initialization, making redundant frame, redundant frame supplementary set is the full null sequence that length is identical with system-frame and verification sequence length thereof.

And described errors present indicator sequence is divided into two kinds, a kind of is all system-frame of this redundant frame coding of the participation of the current redundant frame of receiving and correspondence thereof to be carried out to XOR process (being referred to as) participation frame errors present indicator sequence obtained; Another kind is the redundant frame supplementary set (being current redundant frame supplementary set) after upgrading and the vicious system-frame of institute that has neither part nor lot in current redundant frame coding to be carried out to (being referred to as) that the XOR processing obtains have neither part nor lot in frame errors present indicator sequence.

Described recovery system frame process in two sub-sections, the one, recover to participate in the system-frame that current redundant frame is encoded, its process by: in the vicious system-frame that participates in current redundant frame coding, be designated as wrong position (position that namely this sequence intermediate value is 1) and carry out bit reversal in participating in frame errors present indicator sequence, all according to Frame Check Sequence, carry out the frame detection after each bit reversal, if testing result is correct, the frame after this bit reversal is just corresponding correct system-frame, and by recovering rear correct system-frame and current redundant frame, carrying out the XOR processing, this correct system-frame is weeded out from the frame that participates in current redundant frame coding, the 2nd, recover to have neither part nor lot in the error system frame that current redundant frame is encoded, its process is identical with last process, the system-frame that just will recover is the error system frame that has neither part nor lot in current redundant frame coding, and the errors present indicator sequence is for having neither part nor lot in frame errors present indicator sequence, and change current redundant frame into current redundant frame supplementary set.And the number of wherein said bit reversal carries out according to the mode increased progressively from small to large, minimum is 1, and maximum number is determined by the decoder complexity.

Describedly take out half or 1 at random from current all system-frame of failing to recover, and their frame number is sent to transmitting terminal from feedback channel, its half principle of still taking out 1 system-frame of taking out all system-frame by the sum of reception error system frame do not change for continuous 2～3 times, take out randomly 1 system-frame, otherwise just take out all system-frame half, send to transmitting terminal from feedback channel.

The present invention has following advantage with respect to traditional other coding and decoding method of frame level: because receiving terminal can recover erroneous frame by simple interpretation method, thereby, with respect to technology such as traditional ARQ, no-rate codes, network codes, can very effectively improve system transmission capacity; And the employing feedback mechanism, the reception condition that transmitting terminal can feed back according to receiving terminal is carried out next step coding again, thereby its efficiency of transmission is high than the efficiency of transmission of the frame grade encoding technology without feedback mechanism again; Transmitting terminal of the present invention only to those wrong frame encoded, thereby reduced widely again and participated in the number of frames of coding and the complexity of coding&decoding; Participate in and do not require that erroneous frame is continuous because coding allows a lot of erroneous frame in addition, with respect to traditional frame folding, error correcting capability, having had greatly and promoted.Thereby the complexity that the present invention has coding&decoding is low, error correcting capability is strong, and the transmission capacity of system is large, efficiency of transmission and reliability high.

Embodiment:

A. transmitting terminal:

A. framing: the initial data that the length of being sent by information source is 1000 bits is sent into the framing processing module, carries out framing, forms the frame that 10 each length are 100;

B. framing processing: the signal after framing is sent to into frame module, the CRC check sequence that is 16 bits at each frame back intubating length;

C. the frame coding is processed and sent: the signal through framing processing is admitted to the frame coding module, and the frame cataloged procedure divides two steps, and first step is that 10 frames continuously last module being sent here are delivered to next module; Second step is to send redundant frame, according to i moment receiving terminal, feeds back frame number information C _i, C _ibe a set that comprises one or more system-frame frame numbers, with regard to accordingly these system-frame being carried out to (comprising verification sequence, lower same) XOR, obtain a redundant frame R _i, and deliver to next module, till this process is repeated to always and receives the confirmation signal received that receiving terminal sends;

D. add the incoming frame identifier: the information after the frame coding module is processed is admitted to and adds the frame number processing module,, in each frame, comprises system-frame and redundant frame, increases the frame number of unique this frame of identification, is sent to afterwards next module;

E. signal is processed and sent: the information after adding frame identifier resume module is admitted to the normal signal processing module, to signal interweaved, after modulation treatment, deliver to channel and send;

B. receiving terminal:

A. signal receives and conventional treatment: the signal of sending here from channel is sent to signal processing module, carries out the processing such as conventional demodulation, deinterleaving of signal;

B. the Check processing of frame: the signal after demodulation, deinterleaving are processed is transported to frame detector (module), 10 system-frame that this detector first will be received, remove frame number, and according to former frame number, this frame is kept in corresponding frame memory, then detect this system-frame to mistake according to CRC, and result is kept in the relevant position of a frame quality buffer; The frame memory of present embodiment is one can preserve the memory space that 10 each length are 116 bits, and frame quality buffer is a buffer that 10 bit storage space are arranged; This detector is directly given next module after the redundant frame of receiving is removed to frame number;

C. decoding is processed: the redundant frame after frame detector is processed is transported to decoder, and the redundant frame that the note current time is received is R ' _i, the system-frame set that participates in encoding at transmitting terminal corresponding to this redundant frame is C _i, the frame set that has neither part nor lot in coding in the note erroneous frame is C _i, C _inamely in frame quality buffer, all error system frames are deducted C _iremaining error system frame set, make R ' _i=R ' _i+ R ' _i-1+ R ' _i-1be redundant frame supplementary set constantly of i (annotate: here+be XOR, lower with), wherein, R ' _i-1and R ' _i-1be respectively redundant frame and the redundant frame supplementary set of previous moment, initialization makes R ' ₀and R ' ₀be all the full null sequence that length is 116, C ₁for empty set, then as follows to C _iin system-frame recovered:

(1). from find out C in the frame memory of a module _ithe all system-frame that comprise, mistake in computation position indicator sequence E=R ' _i+ sum (C _i), sum (C here _i) the computing meaning is to C _iin all elements carry out XOR, and the number of establishing " 1 " in E is d;

(2). v " 1 " is taken out in the d from E " 1 " position, is placed on original position, and other positions form a sequence E ' for " 0 ", and initialization v gets 1, total C _d ^vfollow the example of, here C _d ^vrefer in d the number of combinations of getting v, each is followed the example of to the E ' obtained, again with C _iin each of all system-frame carry out respectively XOR and obtain a series of exploration system-frame S _t, each is soundd out to system-frame S _tcarry out the frame detection according to Frame Check Sequence, if testing result is correct, this exploration system-frame is just the right value of corresponding system frame, then following information is upgraded: by the S that is updated to of corresponding system frame in frame memory _t; By the corresponding position of frame quality buffer, be updated to correct; By R ' _ibe updated to R ' _i+ S _tif testing result is incorrect, continue the calculating of next exploration system-frame, once C in computational process _iall system-frame all be resumed, turn to step [3], otherwise translator goes on always; As all E ' and all C _iin system-frame all sound out one time after, C _ialso have system-frame not to be resumed, if v<p, by v, from adding 1, the complexity that the value of p is arranged by decoder here determines, and repeats this process, if v reaches the p value, turns to step [3];

To C _iin recovery process and the C of system-frame _iin system-frame recovery process consistent, as long as by the C in (1) and (2) _ichange C into _i, by R ' _ichange R ' into _i, carry out (1) and (2) computing and get final product;

(3). the data of the frame quality buffer in the module that decoding is processed are sent to feedback processing modules, if there is no the error system frame in frame quality buffer, turn to steps d, otherwise, sum (is not generally 2-3 time) continuously several times and changes, get randomly a frame number and constantly participate in code set C as next from the error system frame number _i+1, remaining error system frame number is just C _i+1, otherwise from all error system frame numbers the random frame number of selecting half as C _i+1, remaining half as C _i+1, then by C _i+1feed back to transmitting terminal by feedback channel, this process be repeated until all system-frame indication in frame quality buffer be all correct till, at this time feed back the confirmation signal that one of transmitting terminal receives;

D. the system-frame of full recovery in frame memory or part recovery is delivered to the stay of two nights.