CN103095440B - Automatic repeat request system and method is mixed in free space optical communication - Google Patents

Abstract

The invention discloses a hybrid automatic request retransmission system and method in free space optical communication, which mainly solves the reliability problem in the existing free space optical communication system. Under the control, adaptive block and error detection decoding are performed on the transmitted data; the error correction coding module performs error correction decoding on the data after error detection decoding; the diversity transmission control module performs error correction under the control of the adaptive control module The decoded data is sent in adaptive diversity; the diversity receiving module performs diversity reception on the received data; the code combination and error correction decoding module performs adaptive code combination and error correction decoding on the diversity received data under the control of the adaptive control module; The block-by-block error detection and decoding module performs block-by-block decoding on the error-correction decoding data and requests retransmission. The invention improves the reliability of the communication system, takes into account the real-time performance and transmission efficiency of the communication, and can be used in the field of free space optical communication.

Description

Hybrid automatic request retransmission system and method in free space optical communication

technical field

The present invention belongs to the technical field of communication, and further relates to a hybrid automatic repeat request (HARQ) system and method in free space optical communication (FreeSpace Optical, FSO) in the technical field of error control of free space optical communication. The invention can be used in a free space optical communication system that has higher requirements on real-time performance, reliability and transmission efficiency.

Background technique

Free space optical communication is a new type of broadband wireless communication technology that uses light (mainly laser) as a carrier to communicate in free space. It has many advantages such as high modulation rate, wide frequency bandwidth, large capacity, no spectrum resource occupation, good confidentiality, low cost, fast installation, transparent protocol, flexible and convenient networking, etc. It is recognized as one of the best ways for future broadband mobile communications First, it has broad application prospects. In recent years, with the basic completion of the backbone network, the emergence of the last mile problem, the continuous development of various technologies, the gradual maturity of equipment development, and the drive of broadband data services and rapid emergency services, FSO is one of the hot communication technologies. received widespread attention.

FSO is greatly affected by weather factors, terrain conditions, and foreign objects, especially random errors and burst errors caused by time-varying, multipath, shadows, and Doppler frequency shifts in atmospheric channels will seriously deteriorate system performance and affect Stability and reliability of FSO system. At the same time, the ever-increasing broadband data services and fast emergency services also put forward higher requirements on the real-time and reliability of the system. Traditional methods to improve communication quality in FSO mainly include large-aperture receiving technology, diversity technology of multi-beam transmission, multi-wavelength transmission technology, partially coherent optical transmission technology, acquisition, aiming and tracking (Acquisition Pointing and Tracking, APT) technology, adaptive optics technology and modulation and demodulation technology, etc. However, these technical methods have certain limitations. They are often only effective when the conditions are good. When the weather conditions are bad and other conditions deteriorate, the performance of these methods will drop sharply or even be ineffective, and there are also varying degrees of small application range and complexity. High, low bandwidth utilization, time extension and other shortcomings.

Therefore, improving the reliability and stability of communication is one of the key technologies of FSO. As an error control technology, HARQ combines the high reliability of Automatic RepeatreQuest (ARQ) and the high effectiveness of Forward Error Correction (FEC). The stability and reliability of FSO communication have been paid attention to by people, but the research on applying it to FSO system is still in its infancy.

There are three main HARQ methods commonly used at present: Type I HARQ retransmits all information sequences and their check sequences and performs code combination; Type II HARQ alternately retransmits information sequences and check sequences and combines them with the sent information sequences or check sequences. The verification sequence is combined and decoded, and the type III HARQ retransmits the information sequence and the verification sequence according to the punctured matrix part. These three HARQ methods have some disadvantages. For example, in the case of burst errors, all errors are usually concentrated in a small part of the data. Even if there are only a small number of bit errors after decoding, the entire data still needs to be retransmitted, resulting in The efficiency of the system is greatly reduced; multiple retransmissions prolong the data transmission time, and real-time reception cannot be guaranteed; the storage capacity of the retransmitted data at the receiving end is large, which consumes resources; the received data cannot be fully combined, and it is easy to lose effective received information. In an existing HARQ system, the following methods are generally adopted to improve system performance.

Zhou Qinying and others proposed a new HARQ method based on block data transmission in "A New HARQ System Based on Block Data Transmission" ("Journal of Xidian University" Natural Science Edition 200532(5): 720-723). This method determines the number of blocks of each frame of data and the number of retransmissions required for correct transmission according to the estimated channel conditions, blocks the data frame and copies each block according to the estimated number of retransmissions, and then The blocks are CRC checked, and finally combined into one data frame for transmission. This method can reduce the feedback delay and improve the real-time performance of the system. However, the disadvantage of this method is that due to the duplication and CRC check of each block of the data frame, the amount of data is large and excessive redundant information is generated; the copied identical blocks are combined and sent together, It will increase the correlation between the blocks, so that the received data cannot be fully combined, which is not conducive to improving the performance of the code combination; and after decoding, the correct block is received, the wrong block is discarded, and no retransmission is performed, which will destroy the integrity of the transmitted data frame. integrity.

A parallel redundant transmission is proposed in the patent "Parallel redundant transmission and parallel combined reception of packet data in hybrid automatic repeat request system" (publication number CN1444352A, application number 02133719.5, application date 2002.9.9) applied by Southwest Jiaotong University Combined with the method of receiving packet data in parallel. In this method, the sending end passes the error correction coded data packet through N puncturing modules, and then sends it in parallel with the number of N puncture modules; the receiving end passes the data packet received in parallel through N depuncturing modules recovery, and then perform code merging processing. The disadvantage of this method is that when applied to CDMA system, the number N of parallel transmission is equal to the number of orthogonal channel codes allocated by CDMA packet data communication system, which is a fixed value and cannot be adjusted adaptively with channel conditions, which is not conducive to Improvement of transmission efficiency; discard packets that still have errors after error correction and decoding and request retransmission, and retransmit the parallel redundant sending and parallel redundant combined reception of the entire packet data, so that even if the error is only concentrated in the packet For a small segment, the entire data still needs to be retransmitted, resulting in a reduction in transmission efficiency.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and provide a hybrid automatic retransmission system and method for free-space optical communication, so as to meet the requirements of free-space optical communication for real-time performance, reliability and transmission efficiency.

In order to achieve the above object, the idea of the present invention is: apply the adaptive block transmission technology, adaptive diversity technology and adaptive code combination technology to the hybrid automatic retransmission system, and dynamically adjust the data frame according to the current channel condition The number of blocks, the number of transmission and reception diversity, the coding mode of each diversity and the method of code combination, thereby improving the reliability of the free space optical communication system, and taking into account real-time and transmission efficiency.

The system of the present invention includes a sending part, a receiving part and a control part, wherein:

The sending part includes a block error detection coding module, an error correction coding module, and a diversity transmission module; the output end of the block error detection coding module is connected to the input end of the error correction coding module, and the output end of the error correction coding module is connected to the input of the diversity transmission module terminal; the block error detection coding module is used to perform adaptive block and block error detection coding on the transmitted data frame under the control of the adaptive control module, and retransmit when the block is wrong; the error correction coding module is used to perform error correction coding on the data frame output by the block error detection coding module; the diversity transmission module is used to perform adaptive diversity transmission on the error correction coded data frame under the control of the adaptive control module.

The receiving part includes a diversity receiving module, a code merging and error correction decoding module, and a block error detection decoding module; the output of the diversity receiving module is connected to the input of the code merging and error correction decoding module, and the code merging and error correction decoding The output end of the module is connected to the input end of the block error detection and decoding module; the diversity receiving module is used for diversity receiving and decoding of the received data frames; the code combination and error correction decoding module is used for adaptive control Under the control of the module, the code combination and error correction decoding are performed on the diversity received data; the block error detection decoding module is used to perform block error detection decoding on the data frames after error correction decoding, and give corresponding feedback information .

The control part includes a signal-to-noise ratio estimation module and an adaptive control module; the output end of the signal-to-noise ratio estimation module is connected to the input end of the adaptive control module, and the output end of the adaptive control module is respectively connected to the input end of the block error detection coding module, The input terminal of the diversity transmission module, code combination and the input terminal of the error correction decoding module are connected; the signal-to-noise ratio estimation module is used to estimate the signal-to-noise ratio of the current channel; the self-adaptive control module is used to The noise ratio estimation information and the number of retransmissions required for the correct transmission of the previous frame data estimate the current channel conditions, and generate control information according to the estimated current channel conditions, so as to realize the block number, Adaptive control of diversity number and encoding mode, code combination and code combination mode in error correction decoding module in diversity sending module.

The method of the present invention comprises two steps in the sending process and the receiving process, wherein:

The specific steps of the sending process include the following:

(1) Generate multiple data blocks:

The data splitting module receives the control information of the self-adaptive control module, performs adaptive blocking on the transmitted data frame according to the block control information in the control information, and generates a plurality of corresponding data blocks.

(2) generate a plurality of error detection coding blocks:

2a) A plurality of error detection coding units perform error detection coding on multiple data blocks, and assign a corresponding block number to each block to generate multiple error detection coding blocks.

2b) The block cache merging module caches multiple error detection coding blocks.

(3) Merge retransmission:

3a) The block cache merging module receives the control information from the adaptive control module.

3b) The block cache merging module judges whether there is a block number of the retransmission block in the received control information, if it exists, then retransmits the error block corresponding to the block number; if it does not exist, the block cache The merging module merges the plurality of error detection coding blocks buffered in step 2b) into a data frame, and sends the data frame to the error correction coding module.

(4) Error correction code:

The error correction encoding module performs error correction encoding on the received data frame, and generates corresponding error correction encoding data.

(5) Adaptive diversity transmission:

5a) The diversity transmission control module receives the diversity control information from the adaptive control module.

5b) Under the control of the diversity control information, the diversity transmission control module adopts an adaptive method to select the diversity number and the HARQ types of I, II, and III respectively, and assigns each diversity type according to the selected HARQ type. Select the encoding mode, the encoding mode is consistent with the selected HARQ type.

5c) The diversity transmission control module encodes the error correction coded data according to the selected coding mode, and generates corresponding diversity coded data.

5d) The sending unit performs diversity sending on the diversity coded data on the corresponding diversity.

The specific steps of the receiving process include the following:

(6) Diversity reception decoding:

6a) The receiving unit detects the received data, and when diversity coded data is detected, performs diversity reception on it.

6b) The diversity decoding and buffering module decodes the diversity encoded data received by each diversity, and generates corresponding diversity decoding data.

6c) The diversity decoding and buffering module buffers the diversity decoding data.

(7) code merge:

The code combination and error correction decoding module receives the control information of the adaptive control module, and performs code combination processing on the diversity decoding data according to the code combination control information in the control information, and generates corresponding code combination data.

(8) Error correction decoding:

The code combination and error correction decoding module performs error correction decoding on the code combination data to generate corresponding error correction decoding data.

(9) block error detection decoding:

9a) The data splitting module divides the error correction decoding data into blocks, and generates a plurality of corresponding data blocks.

9b) The error detection decoding unit performs error detection decoding on a plurality of data blocks, and generates a plurality of error detection decoding blocks including correctness and error.

9c) The block cache merging module caches the blocks after the error detection coding, requests retransmission of the wrong error detection decoding block, and records the block number and retransmission times of the correct error detection decoding block, When all blocks are received correctly or the number of retransmissions reaches the maximum value set by the system, each block is combined into a data frame for submission.

Compared with the prior art, the present invention has the following advantages:

First, the present invention realizes the matching between the number of blocks of a data frame and the current channel condition because the system adopts a structure based on adaptive block transmission and an adaptive block transmission method, and only retransmits erroneous blocks, overcoming The disadvantages of poor channel adaptability and low transmission efficiency of non-block or fixed block transmission in the prior art are eliminated, so that the present invention improves the transmission efficiency and real-time performance of the system.

Second, the present invention realizes the dynamic adjustment of the diversity number according to the current channel conditions because the system adopts the adaptive diversity-based structure and adaptive diversity method, overcomes the simultaneous serial transmission of multiple identical data blocks in the prior art, The disadvantage of increasing the correlation between blocks, so that the received data cannot be fully combined, enables the present invention to reduce the correlation between data frames, improve the performance of code merging, thereby increasing the reliability of error correction decoding and reducing the number of retransmissions , to reduce the time delay of the system; at the same time, it also overcomes the disadvantage of poor channel adaptability of the fixed diversity in the prior art, so that the present invention can improve the transmission efficiency of the system.

Third, because the present invention adopts the adaptive coding method for each diversity set, and adjusts the coding mode of each diversity set through the puncturing matrix, it realizes the dynamic adjustment of the selected HARQ type according to the current channel condition, only by dynamically adjusting the puncturing The format of the remainder matrix is used to realize the dynamic adjustment of the encoding mode, thereby avoiding the simultaneous configuration of three independent types of HARQ in the system, so that the present invention can effectively take into account the system transmission efficiency and reliability, reduce system complexity, and reduce the need for The consumption of hardware resources achieves the unified effect of system performance and implementation complexity.

Fourth, because the present invention adopts the adaptive code combination method, it realizes the matching between the code combination mode and the current channel condition and the HARQ type adopted, and overcomes the shortcoming of using a single code combination method in the prior art that is poor in adaptability to the channel, making the present invention The invention can improve the code combination performance of the system and increase the decoding reliability.

Fifth, when the present invention performs code combination processing on the retransmitted data, the retransmitted data frame is combined with the data frame after the error correction decoding of the previous transmission, which overcomes the fact that the code combination in the prior art cannot fully utilize the correction The disadvantage of effective information added in the wrong decoding process enables the present invention to improve the code combination performance of the system, increase the decoding reliability, further reduce the number of retransmissions, and reduce the system delay.

Description of drawings

Fig. 1 is a system block diagram of the present invention;

Fig. 2 is a schematic structural diagram of the sending part in the system of the present invention;

Fig. 3 is a schematic structural diagram of the receiving part in the system of the present invention;

Fig. 4 is a flow chart of sending process in the method of the present invention;

Fig. 5 is a flowchart of the receiving process in the method of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Referring to accompanying drawing 1, the system of the present invention includes sending part, receiving part and control part.

The sending part includes block error detection coding module, error correction coding module and diversity sending module.

The output end of the block error detection encoding module is connected to the input end of the error correction encoding module, and the output end of the error correction encoding module is connected to the input end of the diversity sending module. The block error detection coding module is used for performing adaptive block and block error detection coding on the transmitted data under the control of the adaptive control module, and performing retransmission when block error occurs. The error correction coding module is used to perform error correction coding on the data frame output by the block error detection coding module. The diversity sending module is used to perform adaptive diversity sending on the error correction coded data frame under the control of the adaptive control module.

The block error detection coding module in the sending part includes a data splitting module, M (M is an integer greater than 1) error detection coding units and a block buffer merging module, and the block error detection coding module is described in accompanying drawing 2 The structural relationship among the included data splitting module, M error detection coding units and block cache merging module. The M output terminals of the data splitting module are respectively connected to the input terminals of the M error detection coding units, and the output terminals of the M error detection coding units are respectively connected to the M input terminals of the block buffer merging module, and the block buffer merging module The output end of the self-adaptive control module is connected to the input end of the error correction coding module, and the output end of the self-adaptive control module is respectively connected to the input end of the data splitting module and the input end of the block cache merging module.

The data splitting module is used for adaptively dividing the transmitted data frame into blocks under the control of the adaptive control module, and sending the blocks to the error detection coding unit.

M error detection coding units are configured to perform error detection coding on each block, and send the block after error detection coding to the block buffer merging module. M is an integer greater than 1, and its maximum value is determined by the application environment of the system and the block strategy. The number used in practice is the same as the actual number of blocks after each sent data is divided into blocks by the data splitting module.

The block cache merging module is used for caching and merging the blocks after the error detection encoding, and sending the merged data frame to the error correction encoding module, and under the control of the adaptive control module to correct the erroneous blocks Make a retransmission.

The diversity transmission module in the transmission part includes a diversity transmission control module and N (N is an integer greater than 1) transmission units, and the diversity transmission control module included in the diversity transmission module and the N transmission units are described in the accompanying drawing 2 structural relationship. The output end of the error correction coding module is connected to the input end of the diversity transmission control module, the N output ends of the diversity transmission control module are respectively connected to the input ends of N transmission units, and the output end of the adaptive control module is connected to the input of the diversity transmission control module end.

The diversity transmission control module is used to adaptively select the diversity number of data transmission and the coding mode of each diversity according to the control information of the adaptive control module.

N sending units are used to send each diversity data frame. N is an integer greater than 1, and its maximum value is determined by the system's application environment and diversity strategy. The actual number used is the same as the diversity number selected by the diversity transmission control module.

The receiving part includes a diversity receiving module, a code combination and error correction decoding module, and a block error detection decoding module.

The output end of the diversity receiving module is connected to the input end of the code combination and error correction decoding module, and the output end of the code combination and error correction decoding module is connected to the input end of the block error detection decoding module. The diversity receiving module is used for performing diversity reception and decoding on the received data frames. The code combination and error correction decoding module is used for performing code combination and error correction decoding on the diversity received data under the control of the adaptive control module. The block-by-block error detection and decoding module is used to perform block-by-block error detection and decoding on the error-corrected and decoded data frames, and provide corresponding feedback information.

The diversity receiving module in the receiving part includes N (N is an integer greater than 1) receiving units and a diversity decoding buffer module. The structural relationship among them is shown. The output terminals of the N receiving units are respectively connected to the N input terminals of the diversity decoding buffer module, and the output terminals of the diversity decoding buffer module are connected to the input terminals of the code combining and error correction decoding module.

N receiving units are used to receive each diversity data frame, N is an integer greater than 1, and its maximum value is the same as the maximum value of the number of sending units in the diversity sending module, and the number used in practice is the same as the actual number of sending units The number of episodes is the same.

The diversity decoding and buffering module is used to decode and buffer each diversity received data frame, and send the decoded data frame to the code combination and error correction decoding module.

The block error detection and decoding module in the receiving part includes a data splitting module, M (M is an integer greater than 1) error detection and decoding units and a block buffer merging module. The structural relationship between the data splitting module, the M error detection decoding units and the block buffer merging module included in the block error detection decoding module is described in Fig. 3 . The output end of the code merging and error correction decoding module is connected to the input end of the data splitting module, the M output ends of the data splitting module are respectively connected to the input ends of M error detection decoding units, and the M error detection decoding units The output terminals of are respectively connected to the M input terminals of the block cache merging module.

The data splitting module is used to divide the received data frame after the error correction encoding into blocks, and send the blocks to the error detection decoding unit.

M error detection decoding units are used to perform error detection encoding on each block, and send the error detection coded block to the block buffer merging module, M is an integer greater than 1, and its maximum value is the same as the block The error detection coding module is the same, and the actual number used is the same as the actual number of blocks after each received data is divided into blocks by the data splitting module.

The block cache merging module is used to cache the blocks after the error detection encoding, and request to retransmit the wrong error detection decoding blocks. When all the blocks are received correctly or the number of retransmissions reaches the maximum value set by the system After that, merge the blocks into one data frame for submission.

The control part includes a signal-to-noise ratio estimation module and an adaptive control module.

The output end of the signal-to-noise ratio estimation module is connected to the input end of the adaptive control module, and the output end of the adaptive control module is respectively connected to the input end of the block error detection coding module, the input end of the diversity transmission module, code combination and error correction decoding connected to the input of the module. The signal-to-noise ratio estimation module is used to estimate the signal-to-noise ratio of the current channel; the adaptive control module is used to estimate the current Estimate the channel conditions, and generate control information according to the estimated current channel conditions, and realize the block number of the transmitted data frame in the block error detection coding module, the diversity number and coding mode in the diversity transmission module, code combination and error correction decoding Adaptive control of the code combination mode in the module.

The method of the invention includes a sending process and a receiving process.

Referring to Fig. 4, the sending process in the method of the present invention is further described.

Step 1, generate multiple data blocks.

The signal-to-noise ratio estimation module estimates the signal-to-noise ratio of the current channel, and sends the signal-to-noise ratio estimation information to the adaptive control module. Estimate the current channel conditions; if the data has been sent, the adaptive control module will estimate the current channel conditions based on information such as signal-to-noise ratio estimation information, feedback information, and the number of retransmissions required for the correct transmission of the previous frame of data. . The adaptive control module performs adaptive segmentation on the transmitted data frame according to the estimated current channel condition: if the current channel condition is good, the number of divisions is reduced, and if the current channel condition is poor, the number of divisions is increased. The increased or decreased number of blocks is consistent with the changing trend of the current channel condition. The adaptive control module compares the estimated current channel condition with the last estimated channel condition. If the current channel condition changes greatly, the increased or decreased The number of sub-blocks is large, and if the current channel condition changes little, the number of sub-blocks to be increased or decreased is small. The adaptive control module puts the number of blocks into the block control information and sends it to the data splitting module. The data splitting module adaptively blocks the sent data according to the block number in the block control information, and generates multiple The data blocks are sent to corresponding units in the M error detection coding units. If the number of data blocks is less than M, the number of units actually used is the same as the number of blocks.

Step 2, generate a plurality of error detection coding blocks.

M error detection coding units perform error detection coding on the received data blocks, assign corresponding block numbers to each block, generate corresponding multiple error detection code blocks, and send the error detection code blocks Cache for the block cache merge module.

Step 3, merge and retransmit.

The adaptive control module judges whether there is an erroneous block that needs to be retransmitted according to the feedback information. If there is, the block number of the block that needs to be retransmitted is put into the retransmission control information and sent to the block cache merging module; if not , then no block number is put in the retransmission control information. The block cache merging module judges whether there is a block that needs to be retransmitted according to the retransmission control information, and if it exists, retransmits the corresponding block according to the block number in the retransmission control information; The buffered blocks are combined into a data frame, and the data frame is sent to the error correction coding module.

(4) Error correction coding.

The error correction encoding module performs error correction encoding on the received data frame, generates corresponding error correction encoding data, and sends the error correction encoding data to the diversity sending module.

(5) Adaptive diversity transmission.

The signal-to-noise ratio estimation module estimates the signal-to-noise ratio of the current channel, and sends the signal-to-noise ratio estimation information to the adaptive control module. The current channel condition is estimated; if the data has been sent, the adaptive control module estimates the current channel condition based on information such as signal-to-noise ratio estimation information, feedback information, and the number of retransmissions required for correct transmission of the previous frame of data.

The adaptive control module adaptively selects the diversity number and HARQ type according to the estimated current channel conditions, and puts the selected diversity number and HARQ type into the diversity control information and sends them to the diversity transmission control module, and the diversity transmission control The module selects the diversity number and HARQ type according to the diversity number and HARQ type in the diversity control information, and selects the corresponding coding mode for each diversity according to the selected HARQ type.

The adaptive control module estimates the number of retransmissions required for the current correct transmission of a data frame according to the estimated current channel conditions, and determines the number of diversity by the estimated number of retransmissions: if the current channel conditions are good, the number of retransmissions required is small , then reduce the diversity number accordingly, if the current channel condition is bad and the required number of retransmissions is large, then increase the diversity number accordingly.

The adaptive control module selects the type of hybrid automatic repeat request HARQ according to the estimated current channel condition: if the current channel condition is good, select type I hybrid automatic repeat request HARQ; if the current channel condition is medium, select type II hybrid automatic request repeat Transmit HARQ; if the current channel condition is poor, select type III hybrid automatic retransmission HARQ.

The adaptive control module puts the selected diversity number and HARQ type into the diversity control information and sends them to the diversity transmission control module, and the diversity transmission control module selects the diversity number and the HARQ type according to the diversity number and the HARQ type in the diversity control information, and A corresponding coding mode is selected for each diversity set according to the selected HARQ type. The coding mode is realized by selecting the corresponding puncture matrix: when using type I hybrid automatic retransmission HARQ, use the fixed coding puncture matrix; when using type II or type III hybrid automatic retransmission HARQ, use rate matching The censored matrix of .

The diversity transmission control module encodes the error correction coded data according to the selected coding mode, generates corresponding diversity coded data, and sends the diversity coded data to corresponding units in the N sending units according to the selected diversity number. If the selected diversity number is less than N, the actual number of units used is the same as the diversity number.

The sending unit performs diversity sending on the diversity coded data on the corresponding diversity.

Referring to accompanying drawing 5, the receiving process in the method of the present invention is further described.

Step 6, diversity reception decoding.

The N receiving units detect the received data, and when the diversity coded data is detected, they perform diversity reception on it, and send the received diversity coded data to the diversity decoding buffer module. If the number of actually received diversity coded data is less than N, the number of units actually used is the same as the number of actually received diversity coded data.

The diversity decoding and buffering module decodes and buffers the diversity encoded data received by each diversity, generates corresponding diversity decoding data, and sends the diversity decoding data to the code combining and error correction decoding module.

Step 7, code merging.

The signal-to-noise ratio estimation module estimates the signal-to-noise ratio of the current channel, and sends the signal-to-noise ratio estimation information to the adaptive control module. Estimate the current channel conditions; if the data has been sent, the adaptive control module will estimate the current channel conditions based on information such as signal-to-noise ratio estimation information, feedback information, and the number of retransmissions required for the correct transmission of the previous frame of data. . The adaptive control module selects a code combination method that matches the current channel condition according to the estimated current channel condition: when the channel condition is good, the Chase combination method is used, and when the channel condition is poor, the incremental redundancy IR combination method is used. The adaptive control module puts the selected code combination method type into the code combination control information and sends it to the code combination and error correction decoding module, and the code combination and error correction decoding module selects according to the code combination method type in the code combination control information Corresponding code combination method. When code combining is performed, the same block in multiple diversity decoding data can be diversity combined. When a block needs to be retransmitted, the retransmitted data frame is combined with the error-corrected and decoded data frame transmitted last time, so as to utilize the effective information added in the error-corrected and decoded process.

Step 8, error correction decoding.

The code combination and error correction decoding module performs error correction decoding on the code combination data, generates corresponding error correction decoding data, and sends the error correction decoding data to the block error detection decoding module.

Step 9, block error detection decoding.

The data splitting module divides the error correction decoding data into blocks, generates corresponding multiple data blocks, and sends the multiple data blocks to corresponding units in the M error detection coding units. If the number of data blocks is less than M, the number of units actually used is the same as the number of blocks.

The error detection decoding unit performs error detection decoding on a plurality of data blocks, and generates a plurality of error detection decoding blocks including correctness and error.

The block cache merging module caches the block after the error detection code, if there is an error block in the received block, it will feed back the block number of the wrong block as feedback information to the sender, and request retransmission Wrong error detection decoding blocks. If all blocks are received correctly or the number of retransmissions reaches the maximum value set by the system, each block will be combined into a data frame for submission.

Claims (10)

1., for mixing an automatic repeat request system in free space optical communication, comprise transmitting portion, receiving unit and control section, wherein:

Described transmitting portion comprises piecemeal error detection coding module, error correction coding module, diversity transmission module; The output of piecemeal error detection coding module connects the input of error correction coding module, and the output of error correction coding module connects an input of diversity transmission module; Described piecemeal error detection coding module, under controlling at self-adaptive control module, carries out the error detection coding of self adaptation piecemeal and piecemeal, and retransmits when piecemeal is made mistakes to transmission Frame; Described error correction coding module, carries out error correction coding for the Frame exported piecemeal error detection coding module; Described diversity transmission module, under controlling at self-adaptive control module, carries out adaptive diversity transmission to the Frame after error correction coding;

Described receiving unit comprises diversity reception module, Code combination and error-correcting decoding module, piecemeal error detection decoding module; The output of described diversity reception module connects an input of Code combination and error-correcting decoding module, and Code combination is connected the input of piecemeal error detection decoding module with the output of error-correcting decoding module; Described diversity reception module, for carrying out diversity reception and decoding to the Frame received; Described Code combination and error-correcting decoding module, carry out Code combination and error-correcting decoding to diversity reception Frame under controlling at self-adaptive control module; Described piecemeal error detection decoding module, for carrying out piecemeal error detection decoding to the Frame after error-correcting decoding, and provides corresponding feedback information;

Described control section comprises signal-to-noise ratio (SNR) estimation module, self-adaptive control module; The output of signal-to-noise ratio (SNR) estimation module connects the input of self-adaptive control module, and three outputs of self-adaptive control module are connected with another input of error-correcting decoding module with the input of piecemeal error detection coding module, another input of diversity transmission module, Code combination respectively; Described signal-to-noise ratio (SNR) estimation module, for estimating the signal to noise ratio of present channel; Described self-adaptive control module, current channel condition is estimated for correctly transmitting required number of retransmissions according to feedback information, signal-to-noise ratio (SNR) estimation information and previous frame data, produce control information according to the current channel condition estimated, realize the adaptive control to Code combination mode in diversity number in the block count sending Frame in piecemeal error detection coding module, diversity transmission module and coding mode, Code combination and error-correcting decoding module.

2. the mixing automatic repeat request system for free space optical communication according to claim 1, is characterized in that: the piecemeal error detection coding module in described transmitting portion comprises Data Division module, multiple error detection coding unit and point block cache and merges module; Multiple outputs of Data Division module connect the input of multiple error detection coding unit, the input that the output of multiple error detection coding unit merges module with point block cache is respectively connected, the output dividing block cache to merge module connects the input of error correction coding module, and first output of self-adaptive control module is connected with another input that point block cache merges module with the input of Data Division module respectively; Wherein:

Described Data Division module, under controlling at self-adaptive control module, carries out self adaptation piecemeal to transmission Frame, and piecemeal is sent to error detection coding unit;

Described multiple error detection coding unit, for carrying out error detection coding to each piecemeal, and the piecemeal after error detection coding is sent to a point block cache merging module, the number of error detection coding unit be greater than 1 integer, its maximum is determined by systematic difference environment and partition strategy, and the unit number used in reality sends Frame with each, and to carry out the actual block count after piecemeal through Data Division module identical;

Described point block cache merges module, for carrying out buffer memory and merging to the block data frame after error detection coding, and by the dataframe after merging to error correction coding module, retransmits under the control of self-adaptive control module to the piecemeal of makeing mistakes.

3. the mixing automatic repeat request system for free space optical communication according to claim 1, is characterized in that: the diversity transmission module in described transmitting portion comprises diversity transmission control module and multiple transmitting element; The output of error correction coding module connects an input of diversity transmission control module, multiple outputs of diversity transmission control module are connected with the input of multiple transmitting element respectively, and second output of self-adaptive control module connects another input of diversity transmission control module; Wherein:

Described diversity transmission control module, the coding mode for the diversity number that sends data according to the control information of self-adaptive control module and each diversity carries out adaptively selected;

Described multiple transmitting elements, for sending the Frame of each diversity, the number of transmitting element be greater than 1 integer, its maximum is determined by systematic difference environment and diversity strategy, and the unit number used in reality is identical with diversity number selected by diversity transmission control module.

4. the mixing automatic repeat request system for free space optical communication according to claim 1, is characterized in that: the diversity reception module in described receiving unit comprises multiple receiving element and diversity translated code cache module; The output of multiple receiving element is connected with multiple inputs of diversity translated code cache module respectively, and the output of diversity translated code cache module connects an input of Code combination and error-correcting decoding module; Wherein:

Described multiple receiving elements, for receiving the Frame of each diversity, the number of receiving element be greater than 1 integer, the number of receiving element is identical with the number of transmitting element in transmitting diversity module;

Described diversity translated code cache module, for carrying out decoding and buffer memory to the Frame of each diversity reception, and by the dataframe after decoding to Code combination and error-correcting decoding module.

5. the mixing automatic repeat request system for free space optical communication according to claim 1, is characterized in that: the piecemeal error detection decoding module in described receiving unit comprises Data Division module, multiple error detection decoding unit and point block cache and merges module; Multiple outputs of Data Division module are connected with the input of multiple error detection decoding unit respectively, the input that the output of multiple error detection decoding unit merges module with point block cache is respectively connected, and the output connection data of Code combination and error-correcting decoding module splits the input of module; Wherein:

Described Data Division module, for carrying out piecemeal to the receiving data frames after error correction coding, and is sent to error detection decoding unit by piecemeal;

Described multiple error detection decoding units, for carrying out error detection coding to each piecemeal, and the piecemeal after error detection coding is sent to a point block cache merging module, the number of error detection decoding unit be greater than 1 integer, in receiving unit, the number of error detection decoding unit is identical with the number of error detection coding unit in transmitting portion;

Described point block cache merges module, for carrying out buffer memory to the piecemeal after error detection coding, the error detection decoding piecemeal of request retransmission mistake, after all piecemeals all correctly receive or number of retransmissions reaches the maximum of default, is merged into a Frame and submits to by each piecemeal.

6., for a mixing automatic request retransmission method for free space optical communication, comprise two steps in process of transmitting and receiving course, wherein:

Described process of transmitting comprises the steps:

(1) multiple deblocking is generated:

Data Division module receives the control information of self-adaptive control module, carries out self adaptation piecemeal, generate corresponding multiple deblocking according to the piecemeal control information in control information to transmission Frame;

(2) multiple error detection coding piecemeal is generated:

2a) multiple error detection coding unit carries out error detection coding to multiple deblocking, and distributes corresponding piecemeal number for each piecemeal, generates multiple error detection coding piecemeal;

2b) divide block cache to merge module and buffer memory is carried out to multiple error detection coding piecemeal;

(3) re-transmission is merged:

Block cache 3a) is divided to merge the control information of module reception self-adaptive control module;

3b) divide block cache to merge module and judge in the control information received, whether to there is the piecemeal number retransmitting piecemeal, if existed, then retransmit with a piecemeal number corresponding piecemeal of makeing mistakes; If there is no, then divide block cache to merge module by step 2b) in multiple error detection coding piecemeals of buffer memory be merged into a Frame, then by this dataframe to error correction coding module;

(4) error correction coding:

Error correction coding module carries out error correction coding to the Frame received, and generates corresponding error correction encoded data frame;

(5) adaptive diversity sends:

5a) diversity transmission control module receives the diversity control information of self-adaptive control module;

5b) diversity transmission control module is under the control of diversity control information, adopt adaptive approach selection diversity number and the mixing automatic repeat request type being respectively I, II, III, according to selected mixing automatic repeat request type be each diversity select coding mode, coding mode is consistent with selected mixing automatic repeat request type;

5c) diversity transmission control module is encoded to error correction encoded data frame according to selected coding mode, generates corresponding diversity coded frame data;

5d) transmitting element carries out diversity transmission to the diversity coded frame data in respective diversity;

Described receiving course comprises the steps:

(6) diversity reception decoding:

6a) receiving element detects receiving data frames, when diversity coded frame data being detected, carries out diversity reception to it;

6b) diversity translated code cache module to each diversity reception to diversity coded frame data carry out decoding, generate corresponding diversity decoding data;

6c) diversity translated code cache module carries out buffer memory to diversity decoding data;

(7) Code combination:

Code combination and error-correcting decoding module receive the control information of self-adaptive control module, carry out Code combination process according to the Code combination control information in control information to diversity decoding data, generate corresponding Code combination data;

(8) error-correcting decoding:

Code combination and error-correcting decoding module carry out error-correcting decoding to Code combination data, generate corresponding error-correcting decoding data;

(9) piecemeal error detection decoding:

9a) Data Division module carries out piecemeal to error-correcting decoding data, generates corresponding multiple block data frames;

9b) error detection decoding unit carries out error detection decoding to multiple Frame piecemeal, generates the multiple error detection decoding piecemeals comprising right and wrong;

9c) divide block cache to merge module and buffer memory is carried out to the piecemeal after error detection coding, the error detection decoding piecemeal of request retransmission mistake, record piecemeal number and the number of retransmissions of correct error detection decoding piecemeal, after all piecemeals all correctly receive or number of retransmissions reaches the maximum of default, each piecemeal is merged into a Frame and submits to.

7. the mixing automatic request retransmission method for free space optical communication according to claim 6, it is characterized in that: the self adaptation piecemeal described in step (1) refers to, the signal to noise ratio of signal-to-noise ratio (SNR) estimation module to present channel is estimated, signal-to-noise ratio (SNR) estimation information is sent to self-adaptive control module, self-adaptive control module estimates current channel condition according to signal-to-noise ratio (SNR) estimation information, according to the current channel condition estimated, piecemeal is carried out to transmission Frame: if current channel condition is good, then reduce block count, if current channel condition is poor, then increase block count, the piecemeal number increased or reduce is consistent with the change trend of current channel condition, block count is put into piecemeal control information and is sent to Data Division module by self-adaptive control module, and Data Division module carries out piecemeal according to the block count in piecemeal control information to transmission Frame.

8. the mixing automatic request retransmission method for free space optical communication according to claim 6, is characterized in that: step 5b) described in the step of adaptive approach as follows:

The first step, the signal to noise ratio of signal-to-noise ratio (SNR) estimation module to present channel is estimated, and signal-to-noise ratio (SNR) estimation information is sent to self-adaptive control module, and self-adaptive control module estimates current channel condition according to signal-to-noise ratio (SNR) estimation information;

Second step, self-adaptive control module estimates the number of retransmissions needed for current correct transmission one Frame according to the current channel condition estimated, selects the diversity number equal with the number of retransmissions estimated;

3rd step, self-adaptive control module, according to the current channel condition estimated by the first step, selects the mixing automatic repeat request of three kinds: if current channel condition is good, then Selective type I mixing automatic repeat request; If current channel condition is medium, then Selective type II mixing automatic repeat request; If current channel condition is poor, then Selective type III mixing automatic repeat request;

4th step, selected diversity number and mixing automatic repeat request type are put into diversity control information and are sent to diversity transmission control module by self-adaptive control module, diversity transmission control module carries out the selection of diversity number and mixing automatic repeat request type according to the diversity number in diversity control information and mixing automatic repeat request type, is that each diversity selects corresponding coding mode according to selected mixing automatic repeat request type.

9. the mixing automatic request retransmission method for free space optical communication according to claim 6, it is characterized in that: step 5b) described in coding mode refer to, the coding mode that diversity transmission control module uses according to selected type mixing automatic repeat request selects corresponding residual matrix: when adopting type i mixing automatic repeat request, use the residual matrix of regular coding; When adopting Type II or type-iii mixing automatic repeat request, use the residual matrix of rate-matched.

10. the mixing automatic request retransmission method for free space optical communication according to claim 6, it is characterized in that: the Code combination process described in step (7) refers to, Code combination and error-correcting decoding module are according to the Code combination information in control information, select the Code combination method matched with current channel condition, when channel conditions are good, use Chase merging method, when channel conditions are poor, use steadily increase redundancy merging method; Identical piecemeal carries out diversity merging, and the Frame after the error-correcting decoding that the Frame of re-transmission and last time transmit merges.