CN103095440B - Automatic repeat request system and method is mixed in free space optical communication - Google Patents
Automatic repeat request system and method is mixed in free space optical communication Download PDFInfo
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Abstract
The invention discloses in a kind of free space optical communication and mix automatic repeat request system and method, mainly solve the integrity problem in existing free-space optical communication system, piecemeal error detection coding module of the present invention, under the control of self-adaptive control module, carries out self adaptation piecemeal and error detection decoding to transmission data; Error correction coding module carries out error-correcting decoding to the data after error detection decoding; Diversity transmission control module carries out adaptive diversity transmission to error-correcting decoding data under the control of self-adaptive control module; Diversity reception module carries out diversity reception to reception data; Code combination and error-correcting decoding module carry out adaptive code merging and error-correcting decoding to diversity reception data under the control of self-adaptive control module; Piecemeal error detection decoding module carries out block-wise decoding and request retransmission to error-correcting decoding data.Invention increases the reliability of communication system, taken into account real-time and the efficiency of transmission of communication, may be used for free space optical communication field.
Description
Technical field
The invention belongs to communication technical field, further relate to a kind of free space optical communication (FreeSpaceOptical in the error-control technique field of free space optical communication, FSO) mixing automatic repeat request (HybridAutomaticRepeatreQuest, HARQ) system and method in.The present invention can be used in the free-space optical communication system had higher requirements to real-time, reliability and efficiency of transmission.
Background technology
Free space optical communication be one in free space with light (mainly referring to laser) for carrier carries out the Wideband wireless communication technology that communicates.It has that modulation rate is high, bandwidth, capacity greatly, do not take frequency spectrum resource, good confidentiality, cost is low, installation is quick, protocol transparent and the plurality of advantages such as networking flexibility is convenient, be one of best mode of generally acknowledged Future broadband mobile communication, thus have broad application prospects.In recent years, along with substantially building up of backbone network, the appearance of last one kilometer problem, the development of each side technology, the maturation gradually of equipment development, and the driving of broadband data service and quick emergency traffic, FSO, as one of Communication Highlights technology, receives the extensive attention of people.
FSO is larger by the impact of weather conditions, orographic condition, exotic, the random error and burst error that time change, multipath, shade, Doppler frequency shift etc. particularly in atmospheric channel cause can severe exacerbation systematic function, affects stability and the reliability of FSO system.Meanwhile, growing broadband data service and quick emergency traffic are also had higher requirement to the real-time of system and reliability.In FSO tradition improve the method for communication quality mainly contain large aperture reception technique, multi-beam transmission diversity technique, multi-wavelength transmission technology, partially coherent optical transport technology, catch, aim at and follow the tracks of (AcquisitionPointingandTracking, APT) technology, adaptive optical technique and modulation-demodulation technique etc.But these technical methods have certain limitation, they are often only effective when condition is better, when weather conditions are severe and other worsening conditions time, it is even invalid that these method performances sharply decline, and in various degree have that range of application is little, complexity is high, bandwidth availability ratio is low, time the shortcoming such as prolongation.
Therefore, the reliability and stability improving communication are one of key technologies of FSO.HARQ combines automatic repeat request (AutomaticRepeatreQuest as a kind of error-control technique, ARQ) high reliability and forward error correction (ForwardErrorCorrection, FEC) high-efficiency, relatively traditional method more effectively can ensure stability and the reliability of FSO communication under severe conditions, thus be subject to people's attention, but the research applied it in FSO system is also in the starting stage.
HARQ mode conventional at present mainly contains three kinds: I type HARQ and information sequence and verification sequence thereof is all retransmitted and carry out Code combination, information sequence and verification sequence alternately retransmit and merge decoding with the information sequence sent or verification sequence by II type HARQ, type III HARQ by information sequence and verification sequence according to punching matrix partial retransmission.These 3 kinds of HARQ modes also exist some shortcomings, and such as, in burst error situation, all mistakes concentrate on the sub-fraction of data usually, even if only there is the mistake of a small amount of bit after decoding, whole data still need to retransmit, and cause system effectiveness significantly to reduce; Repeatedly retransmitting makes data transmission delay long, cannot ensure real-time reception; The memory capacity that sending and receiving end stores data retransmission is large, consumes resources; Receive data cannot fully merge, easily the effective reception information of loss etc.In existing HARQ system, following methods is generally taked to improve systematic function.
The people such as Zhou Qinying propose a kind of novel HARQ method based on block data transmission in " New HARQ System based on block data transmission " (" Xian Electronics Science and Technology University's journal " natural science edition 200532 (5): 720-723).This method determines the block count of every frame data and the number of retransmissions correctly needed for transmission according to the channel situation estimated, piecemeal is carried out to Frame and according to the number of retransmissions estimated, each piecemeal is copied, then CRC check is carried out to each piecemeal, finally merge into a Frame and send.This method can reduce delay of feedback, improves the real-time of system.But the weak point that the method exists is, owing to copying and CRC check each piecemeal of Frame, make data volume large, produce too much redundant information; Send together after the identical point of merged block copied, can increase the correlation of point interblock, making to receive data cannot fully merge, and is unfavorable for improving Code combination performance; And correct piecemeal receives after decoding, the piecemeal of mistake abandons, and does not retransmit, and can destroy the integrality of transmitting data frame.
Propose a kind of parallel redundancy in the patent " parallel redundancy sends and merges with parallel the method receiving grouped data in mixed spin system system " (publication number CN1444352A application number 02133719.5, applying date 2002.9.9) of Southwest Jiaotong University's application to send and walk abreast and merge the method receiving grouped data.The transmitting terminal of the method by the packet carried out after error correction coding after the perforation process of N number of puncture module, then time number of lines be the transmitted in parallel of N; Receiving terminal to parallel receive to packet recover through N number of depuncture module, then carry out Code combination process.The weak point that the method exists is, be applied in cdma system, transmitted in parallel number N equals the orthogonal channel number of codes that CDMA packet data communication system distributes, and is fixed value, adaptive adjustment can not be carried out with channel conditions, be unfavorable for the raising of efficiency of transmission; For after error-correcting decoding still vicious grouping carry out abandoning and request retransmission, retransmit the parallel redundancy still re-executing whole grouped data to send and parallel redundancy merging reception, even if mistake only concentrates on a bit of of grouping like this, whole data still need to retransmit, and cause the reduction of efficiency of transmission.
Summary of the invention
The object of the invention is to overcome above-mentioned the deficiencies in the prior art, a kind of mixed automatic retransfer system for free space optical communication and method are provided, to meet the requirement of free space optical communication to real-time, reliability and efficiency of transmission.
For achieving the above object, thinking of the present invention is: be applied in mixed automatic retransfer system by self adaptation block transmission technology, adaptive diversity technology and adaptive code folding, can according to current channel condition, dynamically adjust the block count of Frame, send and the diversity number of reception, the coding mode of each diversity and Code combination method, thus improve the reliability of free-space optical communication system, and real-time and efficiency of transmission are taken into account.
System of the present invention comprises transmitting portion, receiving unit and control section, wherein:
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 the input of diversity transmission module; 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; Error correction coding module, carries out error correction coding for the Frame exported piecemeal error detection coding module; Diversity transmission module, under controlling at self-adaptive control module, carries out adaptive diversity transmission to the Frame after error correction coding.
Receiving unit comprises diversity reception module, Code combination and error-correcting decoding module, piecemeal error detection decoding module; The output of diversity reception module connects the 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; Diversity reception module, for carrying out diversity reception and decoding to the Frame received; Code combination and error-correcting decoding module, carry out Code combination and error-correcting decoding to diversity reception data under controlling at self-adaptive control module; Piecemeal error detection decoding module, for carrying out piecemeal error detection decoding to the Frame after error-correcting decoding, and provides corresponding feedback information.
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 the output of self-adaptive control module is connected with the input of error-correcting decoding module with the input of piecemeal error detection coding module, the input of diversity transmission module, Code combination respectively; Signal-to-noise ratio (SNR) estimation module, for estimating the signal to noise ratio of present channel; 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, and 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.
Method of the present invention comprises two steps in process of transmitting and receiving course, wherein:
The concrete steps of process of transmitting comprise as follows:
(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, and 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.
(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 according to selected coding mode, generates corresponding diversity coded data.
5d) transmitting element carries out diversity transmission to the diversity coded data in respective diversity.
The concrete steps of receiving course comprise as follows:
(6) diversity reception decoding:
6a) receiving element detects reception data, when diversity coded data being detected, carries out diversity reception to it.
6b) diversity translated code cache module to each diversity reception to diversity coded 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, and 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 deblockings.
9b) error detection decoding unit carries out error detection decoding to multiple deblocking, 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, and 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.
The present invention compared with prior art has the following advantages:
The first, the present invention have employed structure based on self adaptation block transmission and self adaptation block transmission method due to system, achieve the block count of Frame and mating of current channel condition, and only retransmit the piecemeal of makeing mistakes, overcome in prior art and transmit poor to channel adaptability and that efficiency of transmission is low shortcoming without piecemeal or fixed block, make efficiency of transmission and the real-time of the system that invention increases.
The second, the present invention have employed structure based on adaptive diversity and adaptive diversity method due to system, achieve the several dynamic conditioning according to current channel condition of diversity, overcome multiple identical data piecemeal serial simultaneously in prior art to send, the correlation of point interblock is increased, thus the shortcoming that reception data cannot fully merge, make the present invention can reduce correlation between Frame, improve the performance of Code combination, thus increase the reliability of error-correcting decoding, reduce number of retransmissions, reduce the time delay of system; Meanwhile, also overcome the shortcoming of fixing point set pair channel adaptability difference in prior art, make the present invention can improve the efficiency of transmission of system.
3rd, the present invention is owing to adopting the method for adaptive coding to each diversity, and the coding mode of each diversity is adjusted by residual matrix, achieve selected HARQ type according to the dynamic conditioning of current channel condition, only realize the dynamic conditioning to coding mode with the form by dynamic conditioning residual matrix, thus the HARQ simultaneously configuring independently three types in systems in which can be avoided, the present invention is made can effectively to take into account system transfers efficiency and reliability, reduce system complexity, reduce the consumption to hardware resource, reach the unified effect of systematic function and implementation complexity.
Four, the present invention is owing to adopting adaptive code merging method, achieve mating of the HARQ type of Code combination mode and current channel condition and employing, overcome in prior art and use single Code combination method to the shortcoming of channel adaptability difference, make the present invention can improve the Code combination performance of system, increase reliability of decode.
Five, the present invention is when carrying out Code combination process to data retransmission, the Frame retransmitted merges with the last Frame after error-correcting decoding transmitted, overcome Code combination in prior art and can not make full use of the shortcoming of the effective information increased in error-correcting decoding process, make the present invention can improve the Code combination performance of system, increase reliability of decode, and then minimizing number of retransmissions, reduce the time delay of system.
Accompanying drawing explanation
Fig. 1 is system block diagram of the present invention;
Fig. 2 is transmitting portion structural representation in system of the present invention;
Fig. 3 is receiving unit structural representation in system of the present invention;
Fig. 4 is process of transmitting flow chart in method of the present invention;
Fig. 5 is receiving course flow chart in method of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail.
With reference to accompanying drawing 1, system of the present invention comprises transmitting portion, receiving unit and control section.
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 the input of diversity transmission module.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 data.Error correction coding module, carries out error correction coding for the Frame exported piecemeal error detection coding module.Diversity transmission module, under controlling at self-adaptive control module, carries out adaptive diversity transmission to the Frame after error correction coding.
Piecemeal error detection coding module in transmitting portion comprise Data Division module, M (M be greater than 1 integer) individual error detection coding unit and point block cache merge module, describes the structural relation between the Data Division module included by piecemeal error detection coding module, a M error detection coding unit and point block cache merging module in fig 2.M output of Data Division module is connected with the input of M error detection coding unit respectively, M the input that the output of M 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 the output of self-adaptive control module is connected with the input that point block cache merges module with the input of Data Division module respectively.
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.
M error detection coding unit, for carrying out error detection coding to each piecemeal, and is sent to a point block cache merging module by the piecemeal after error detection coding.M be greater than 1 integer, its maximum is determined by systematic difference environment and partition strategy, and the number used in reality sends data with each, and to carry out the actual block count after piecemeal through Data Division module identical.
Dividing block cache to merge module, for carrying out buffer memory and merging to the piecemeal after error detection coding, and by the dataframe after merging to error correction coding module, and under the control of self-adaptive control module, the piecemeal of makeing mistakes being retransmitted.
Diversity transmission module in transmitting portion comprise diversity transmission control module and N (N be greater than 1 integer) individual transmitting element, describe the structural relation between diversity transmission control module included by diversity transmission module and N number of transmitting element in fig 2.The output of error correction coding module connects the input of diversity transmission control module, and N number of output of diversity transmission control module is connected with the input of N number of transmitting element respectively, and the output of self-adaptive control module connects the input of diversity transmission control module.
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.
N number of transmitting element, for sending the Frame of each diversity.N be greater than 1 integer, its maximum is determined by systematic difference environment and diversity strategy, and the number used in reality is identical with diversity number selected by diversity transmission control module.
Receiving unit comprises diversity reception module, Code combination and error-correcting decoding module, piecemeal error detection decoding module.
The output of diversity reception module connects the 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.Diversity reception module, for carrying out diversity reception and decoding to the Frame received.Code combination and error-correcting decoding module, carry out Code combination and error-correcting decoding to diversity reception data under controlling at self-adaptive control module.Piecemeal error detection decoding module, for carrying out piecemeal error detection decoding to the Frame after error-correcting decoding, and provides corresponding feedback information.
Diversity reception module in receiving unit comprise N (N be greater than 1 integer) individual receiving element and diversity translated code cache module, in fig. 3 the N number of receiving element included by diversity reception module and the structural relation between diversity translated code cache module are illustrated.The output of N number of receiving element is connected with N number of input of diversity translated code cache module respectively, and the output of diversity translated code cache module connects the input of Code combination and error-correcting decoding module.
N number of receiving element, for receiving the Frame of each diversity, N be greater than 1 integer, its maximum is identical with the maximum of transmitting element number in diversity transmission module, and the number used in reality is identical with actual transmitting diversity number.
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.
Piecemeal error detection decoding module in receiving unit comprise Data Division module, M (M be greater than 1 integer) individual error detection decoding unit and point block cache merge module.Describe the structural relation between the Data Division module included by piecemeal error detection decoding module, a M error detection decoding unit and point block cache merging module in fig. 3.The output connection data of Code combination and error-correcting decoding module splits the input of module, M output of Data Division module is connected with the input of M error detection decoding unit respectively, and M the input that the output of M error detection decoding unit merges module with point block cache is respectively connected.
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.
M error detection decoding 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, M be greater than 1 integer, identical with piecemeal error detection coding module of its maximum, the number used in reality receives data with each, and to carry out the actual block count after piecemeal through Data Division module identical.
Block cache is divided to merge 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.
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 the output of self-adaptive control module is connected with the input of error-correcting decoding module with the input of piecemeal error detection coding module, the input of diversity transmission module, Code combination respectively.Signal-to-noise ratio (SNR) estimation module, for estimating the signal to noise ratio of present channel; Self-adaptive control module, for correctly transmitting required number of retransmissions according to feedback information, signal-to-noise ratio (SNR) estimation information and previous frame data, current channel condition is estimated, and 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.
Method of the present invention comprises process of transmitting and receiving course.
With reference to accompanying drawing 4, process of transmitting in method of the present invention is described further.
Step 1, generates multiple deblocking.
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, if do not carry out the transmission of data, then self-adaptive control module was estimated current channel condition according to signal-to-noise ratio (SNR) estimation information; If carried out the transmission of data, then self-adaptive control module comprehensive signal-to-noise ratio (SNR) estimation information, feedback information, previous frame data were correctly transmitted the information such as required number of retransmissions and were estimated current channel condition.Self-adaptive control module carries out self adaptation piecemeal according to the current channel condition estimated 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, self-adaptive control module the current channel condition estimated compared with the last channel condition estimated, if it is large that current channel condition changes degree, the piecemeal number then increased or reduce is just many, if it is little that current channel condition changes degree, then the piecemeal number increasing or reduce is just few.Block count is put into piecemeal control information and is sent to Data Division module by self-adaptive control module, Data Division module carries out self adaptation piecemeal according to the block count in piecemeal control information to transmission data, and the multiple deblockings generated are sent to corresponding unit in M error detection coding unit.If deblocking number is less than M, then the unit number used in reality is identical with block count.
Step 2, generates multiple error detection coding piecemeal.
M error detection coding unit carries out error detection coding to the deblocking received, and distributes corresponding piecemeal number for each piecemeal, generates corresponding multiple error detection coding piecemeal, and sends to a point block cache merging module to carry out buffer memory error detection coding piecemeal.
Step 3, merges and retransmits.
According to feedback information, self-adaptive control module judges whether that the piecemeal of makeing mistakes needs to retransmit, if had, then need the piecemeal number of the piecemeal retransmitted to put into Retransmission control information and send to piecemeal buffer memory to merge module; If no, then do not put into any piecemeal number in Retransmission control information.Divide block cache to merge module and judge whether to exist the piecemeal needing to retransmit according to Retransmission control information, if existence, then retransmit corresponding piecemeal according to the piecemeal in Retransmission control information number; If there is no, then the piecemeal of buffer memory in step 2 is merged into a Frame, and 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, and error correction encoded data is sent to diversity transmission module.
(5) adaptive diversity sends.
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, if do not carry out the transmission of data, then self-adaptive control module was estimated current channel condition according to signal-to-noise ratio (SNR) estimation information; If carried out the transmission of data, then self-adaptive control module comprehensive signal-to-noise ratio (SNR) estimation information, feedback information, previous frame data correctly transmitted the information estimation current channel condition such as required number of retransmissions.
Self-adaptive control module is according to the current channel condition estimated, adaptively selected diversity number and mixing automatic repeat request HARQ type, and selected diversity number and HARQ type are put into diversity control information send to diversity transmission control module, diversity transmission control module carries out the selection of diversity number and HARQ type according to the diversity number in diversity control information and HARQ type, and is that each diversity selects corresponding coding mode according to selected HARQ type.
Self-adaptive control module is estimated the number of retransmissions needed for current correct transmission one Frame according to the current channel condition estimated, by the number of retransmissions estimated to determine diversity number: if current channel condition is good, required number of retransmissions is few, then corresponding minimizing diversity number, if current channel condition is poor, required number of retransmissions is many, then corresponding increase diversity number.
Self-adaptive control module selects mixing automatic repeat request HARQ type according to the current channel condition estimated: if current channel condition is good, then Selective type I mixing automatic repeat request HARQ; If current channel condition is medium, then Selective type II mixing automatic repeat request HARQ; If current channel condition is poor, then Selective type III mixing automatic repeat request HARQ.
Selected diversity number and HARQ 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 HARQ type according to the diversity number in diversity control information and HARQ type, and is that each diversity selects corresponding coding mode according to selected HARQ type.Coding mode is by selecting corresponding residual matrix to realize: when adopting type i mixing automatic repeat request HARQ, use the residual matrix of regular coding; When adopting Type II or type-iii mixing automatic repeat request HARQ, use the residual matrix of rate-matched.
Diversity transmission control module is encoded to error correction encoded data according to selected coding mode, generates corresponding diversity coded data, and diversity coded data is sent to corresponding unit in N number of transmitting element according to selected diversity number.If selected diversity number is less than N, then the unit number used in reality is identical with diversity number.
Transmitting element carries out diversity transmission to the diversity coded data in respective diversity.
With reference to accompanying drawing 5, receiving course in method of the present invention is described further.
Step 6, diversity reception decoding.
N number of receiving element detects reception data, when diversity coded data being detected, carries out diversity reception to it, and the diversity coded data received is sent to diversity translated code cache module.If the diversity coded data number received actual is less than N, then the unit number used in reality is identical with the actual diversity coded data number received.
Diversity translated code cache module to each diversity reception to diversity coded data carry out decoding and buffer memory, generate corresponding diversity decoding data, and diversity decoding data sent to Code combination and error-correcting decoding module.
Step 7, Code combination.
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, if do not carry out the transmission of data, then self-adaptive control module was estimated current channel condition according to signal-to-noise ratio (SNR) estimation information; If carried out the transmission of data, then self-adaptive control module comprehensive signal-to-noise ratio (SNR) estimation information, feedback information, previous frame data were correctly transmitted the information such as required number of retransmissions and were estimated current channel condition.Self-adaptive control module selects the Code combination method matched with current channel condition according to the current channel condition estimated: when channel conditions are good, uses Chase merging method, when channel conditions are poor, uses steadily increase redundancy IR merging method.Selected Code combination Method type is put into Code combination control information and is sent to Code combination and error-correcting decoding module by self-adaptive control module, and Code combination selects corresponding Code combination method to error-correcting decoding module according to the Code combination Method type in Code combination control information.When carrying out Code combination, piecemeal identical in multiple diversity decoding data can carry out diversity merging.When needing when there being piecemeal to retransmit, the Frame after the error-correcting decoding that the Frame of re-transmission and last time transmit merges, to utilize the effective information increased in error-correcting decoding process.
Step 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, and error-correcting decoding data are sent to piecemeal error detection decoding module.
Step 9, piecemeal error detection decoding.
Data Division module carries out piecemeal to error-correcting decoding data, generates corresponding multiple deblockings, and multiple deblocking is sent to corresponding unit in M error detection coding unit.If deblocking number is less than M, then the unit number used in reality is identical with block count.
Error detection decoding unit carries out error detection decoding to multiple deblocking, generates the multiple error detection decoding piecemeals comprising right and wrong.
Divide block cache to merge module and buffer memory is carried out to the piecemeal after error detection coding, if there is the piecemeal of mistake in the piecemeal received, then the piecemeal of wrong piecemeal number is fed back to transmitting terminal as feedback information, the error detection decoding piecemeal of request retransmission mistake.If 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.
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.
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