CN101714915B - Data retransmission method and system - Google Patents
Data retransmission method and system Download PDFInfo
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- CN101714915B CN101714915B CN 200910237038 CN200910237038A CN101714915B CN 101714915 B CN101714915 B CN 101714915B CN 200910237038 CN200910237038 CN 200910237038 CN 200910237038 A CN200910237038 A CN 200910237038A CN 101714915 B CN101714915 B CN 101714915B
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Abstract
The invention provides a data retransmission method and system. The method comprises the following specific steps: after receiving K original data packs, performing packet-loss detection by the receiving terminals and sending feedback report to the sending terminal when detecting packet-loss, wherein the feedback report contains packet-loss information of the receiving terminal and K is a natural number; after sending W original data packs, generating a combined pack through network coding according to the received packet-loss information of all the receiving terminals by the sending terminal, wherein W is a natural number; and retransmitting the combined pack by the sending terminal. The method and system of the invention can be used to increase the data retransmission efficiency of wireless broadcast.
Description
Technical field
The present invention relates to wireless communication technology field, particularly relate to a kind of data repeating method for radio communication and a kind of data re-transmission system.
Background technology
Broadcast operation is being played the part of very important role in radio communication, it is not only the basis that on-demand routing protocol carries out route discovery, himself also can be used as the effective means of the unicast or multicast information of transmission.Compare with traditional wire communication, radio communication packet loss phenomenon is comparatively serious, thereby has higher bit error rate and propagation delay time.Therefore, in radio communication broadcasting, must adopt suitable strategy to improve the reliability of broadcast operation.At present, retransmission technique often is used to improve the reliability of transmission.The thought of ordinary retransmission technology based on: transmit leg obtains recipient's error situation by feedback, retransmit the message of data message to recover to make mistakes make mistakes.
In the practical application, in the broadcasting of low packet loss ratio radio communication, lost data packets is distributed on a plurality of receiving nodes usually.At this moment, the packet loss of any one node of a plurality of receiving nodes all requires the source node retransmission data packet may.Like this, existing repeating method needs repeatedly broadcast data packet to carry out the mistake processing, needs large numbers of number of retransmissions, and very high to the occupancy of wireless channel, therefore need to take massive band width, consumes more energy, thereby affects retransmission efficiency.
In a word, need the urgent technical problem that solves of those skilled in the art to be exactly: how can provide a kind of data retransmission scheme for radio broadcasting, in order to improve retransmission efficiency.
Summary of the invention
Technical problem to be solved by this invention provides a kind of data repeating method and system, in order to improve the data re-transmission efficient of radio broadcasting.
In order to address the above problem, the invention discloses a kind of data repeating method, comprising:
Set up the packet loss matrix, described packet loss matrix is used for depositing the packet loss information of all receiving terminals;
Described packet loss information comprises packet loss ID; Corresponding each receiving terminal of the row of described packet loss matrix, the ID of corresponding each packet of described packet loss matrix column, the initial value of described packet loss matrix is 0;
Whenever receive K raw data packets, receiving terminal carries out packet loss detection, and when detecting packet loss, sends feedback report to transmitting terminal, and described feedback report comprises the packet loss information of this receiving terminal, and K is natural number;
W raw data packets of every transmission, transmitting terminal by network code, generate the combination bag according to the packet loss information of all receiving terminals that receive, and W is natural number;
Described according to packet loss information in the packet loss matrix, by network code, the step that generates the combination bag comprises:
Determining step: judge in the current packet loss matrix whether contain non-zero row, if, then carry out finding step, otherwise, combination step carried out;
Finding step: in current packet loss matrix, search the non-zero row of corresponding ID minimum, and the raw data packets that described ID is corresponding is as the combination member;
Find row corresponding to non-zero element in these row, and row corresponding to non-zero element in these row;
Cross out these row and columns, as current packet loss matrix, and return determining step with remaining matrix;
Combination step: described combination member is done mould 2 Hes, obtain the combination bag;
Transmitting terminal retransmits described combination bag.
Preferably, described method also comprises: the step of described generation combination bag comprises: receive the packet loss information from certain receiving terminal; According to described packet loss information described packet loss matrix is upgraded;
W raw data packets of every transmission detects described packet loss matrix, and when detecting packet loss information, according to described packet loss information, by network code, generates the combination bag.
Preferably,
The step of described updating packet loss matrix comprises:
When the packet loss information that receives from i receiving terminal, according to packet loss ID wherein, successively i is capable in the element corresponding with this packet loss ID put 1, and other element during i is capable sets to 0.
Preferably, described method also comprises: receiving terminal is decoded to the combination bag of receiving, obtains raw data packets, if this raw data packets exists, and discard processing then.
Preferably, described feedback report also comprises the re-transmission successful information;
The step of described updating packet loss matrix comprises: when the feedback report that receives from i receiving terminal, check the content of this feedback report, if packet loss information, then according to wherein packet loss ID, the element corresponding with this packet loss ID puts 1 in successively i is capable, and other element during i is capable sets to 0;
If the re-transmission successful information, then the element that i is capable all sets to 0.
Preferably, describedly whenever receive K raw data packets, receiving terminal carries out packet loss detection, and when detecting packet loss, the step that sends feedback report to transmitting terminal comprises:
Initialization step: preset detected parameters a=0; Receiving step: when receiving a packet, if this packet is the raw data packets of not received, then make a=a+1; Pause step: if a＜K then returns receiving step, otherwise, make a=0, and carry out detecting step; Detecting step: whether the ID that judges all packets of receiving is continuous, if, then return receiving step, otherwise, feedback step carried out; Feedback step: from all packets of receiving, find packet loss information, and described packet loss information is fed back to transmitting terminal with the form of feedback report.
The embodiment of the invention also discloses a kind of data re-transmission system, comprising:
Set up module, be used for setting up the packet loss matrix, described packet loss matrix is used for depositing the packet loss information of all receiving terminals; Described packet loss information comprises packet loss ID; Corresponding each receiving terminal of the row of described packet loss matrix, the ID of corresponding each packet of described packet loss matrix column, the initial value of described packet loss matrix is 0;
Detect and feedback module, be used for whenever receiving K raw data packets, carry out packet loss detection, and when detecting packet loss, send feedback report to transmitting terminal, described feedback report comprises the packet loss information of this receiving terminal, and K is natural number;
Combination bag generation module is used for W raw data packets of every transmission, according to the packet loss information of all receiving terminals that receive, by network code, generates the combination bag, and W is natural number;
Specifically comprise: judge in the current packet loss matrix whether contain non-zero row, if then in current packet loss matrix, search the non-zero row of corresponding ID minimum, and the raw data packets that described ID is corresponding is as the combination member; Find row corresponding to non-zero element in these row, and row corresponding to non-zero element in these row; Cross out these row and columns,, and continue to judge as current packet loss matrix with remaining matrix, otherwise, described combination member is done mould 2 He, obtain making up and wrap;
Retransmission module is used for retransmitting described combination bag.
Preferably, described system also comprises:
Described combination bag generation module comprises:
The second receiving element is used for receiving the packet loss information from certain receiving terminal;
Updating block is used for according to described packet loss information described packet loss matrix being upgraded;
Assembled unit is used for W raw data packets of every transmission, described packet loss matrix is detected, and when detecting packet loss information, according to the packet loss information in the described packet loss matrix, by network code, generate the combination bag.
Preferably, described system also comprises:
Decoder module is used for the combination bag of receiving is decoded, and obtains raw data packets, if this raw data packets exists, and discard processing then.
Preferably, described detection and feedback module comprise:
Initialization unit is used for presetting detected parameters a=0;
The first receiving element is used for if this packet is the raw data packets of not received, then making a=a+1 when receiving a packet;
Suspend the unit, be used for when a＜K, returning the first receiving element, otherwise, make a=0, and carry out detecting unit;
Detecting unit is used for judging whether the ID of all packets of receiving is continuous, if, then return the first receiving element, otherwise, feedback unit carried out;
Feedback unit is used for finding packet loss information from all packets of receiving, and described packet loss information is fed back to transmitting terminal with the form of feedback report.
Compared with prior art, the present invention has the following advantages:
The present invention is applied in the characteristic that network code reduces the transmitting information wirelessly amount in the wireless network broadcast re-transmission, adopt regularly the mode of feedback exchanges packet drop between transmitting terminal and a plurality of receiving terminal, with a plurality of packets to be retransmitted, combine with the mode of network code and to be broadcast to all receiving terminals, reach the purpose that retransmits a plurality of packets with a time slot, thereby realize improving the purpose of retransmission efficiency;
Moreover the present invention adopts the packet loss matrix to deposit the packet loss information of all receiving terminals, and follows following strategy according to described packet loss Information generation combination bag the time, namely to any receiving terminal R
i, each combination bag contains at most a R
iPacket loss, therefore, as long as this combination bag and R
iPacket loss relevant, just can guarantee R
iCan from the combination bag of receiving, solve own required packet loss;
In addition, the present invention adopts mould 2 and generates and resolve the combination bag, computing and simple to operate, to hardware and operating system without any specific (special) requirements.
Description of drawings
Fig. 1 is the package head format of a kind of broadcast data packet of the present invention;
Fig. 2 is the flow chart of a kind of data repeating method embodiment 1 of the present invention;
Fig. 3 is the flow chart of a kind of data repeating method embodiment 2 of the present invention;
Fig. 4 is the radio transmission example of a kind of one-to-many of the present invention;
Fig. 5 is a kind of packet loss matrix of the present invention example;
Fig. 6 is a kind of transmitting terminal of the present invention retransmits work based on described packet loss matrix flow chart;
Fig. 7 is the form of a kind of feedback report FP of the present invention;
Fig. 8 is the flow chart of a kind of data repeating method embodiment 3 of the present invention;
Fig. 9 is the structure chart of a kind of data re-transmission system embodiment of the present invention.
Embodiment
For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, the present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.
In practice, network code so that network node is not only realized routing function but also realize encoding function, thereby improves network performance by allowing that the information from different links is carried out coded combination.Merged the concept of coding and route under this brand-new architecture of network code, network performance can reach the theoretical limit of max-flow transmission.Therefore, the broadcast characteristic of the unreliability of Radio Link and physical layer very is fit to use the method for network code.
To sum up analyze, the inventor herein has creatively proposed one of core idea of the embodiment of the invention, namely utilize the broadcast characteristic of wireless transmission medium, with a plurality of packets to be retransmitted, combine with the mode of network code and to be broadcast to all receiving terminals, reach the purpose that retransmits a plurality of packets with a time slot, thereby improve to greatest extent retransmission efficiency.
For the implementation procedure of retransmission scheme of the present invention clearly is described, at first introduce following symbol:
R
i, i=1,2 ..., M:M receiving terminal;
BPH:Broadcast Packet Head, the packet header of broadcast data packet;
FP:Feedback Packet, the feedback report that receiving terminal sends to transmitting terminal;
ACK, NACK: if all packet losses of receiving terminal are all successfully retransmitted, the FP of its transmission this moment is called ACK, if the packet loss that receiving terminal is confiscated in addition, the FP of its transmission is called NACK.
D
j, j=1,2,3 ...: the raw data packets (non-combination bag) of transmitting terminal broadcasting;
L
j, j=1,2,3 ...: packet D
jLength (byte number);
L: the number of the packet that comprises in the combination bag;
P
i: transmitting terminal is to receiving terminal R
iPacket loss.
With reference to figure 1, show packet header (BPH) form of a kind of broadcast data packet of the present invention.The first character of BPH saves to represent whether this bag is the combination bag and comprises what raw data packets.If l=1 represents non-combination bag; If l＞1 represent that this bag is the combination bag, and the inside comprises l raw data packets.The part of back, packet header comprises the section of l 6 bytes, and every section comprises two parts, and wherein the numbering of front 4 byte representation raw data packets (ID) is used j here
iExpression, rear 2 byte representations represent packet
Length.It should be noted that the length of whole packet (adding packet header) is according to " zero padding " above-mentioned principle
With reference to Fig. 2, show the flow chart of a kind of data repeating method embodiment 1 of the present invention, specifically can comprise:
Except the receive data bag, each receiving terminal also should be regularly to transmitting terminal feedback packet drop.In order to alleviate the load of feedback channel, the present invention does not adopt the mode of a bag one feedback, but receives whenever K raw data packets checks current whether packet loss arranged.If packet loss is arranged, just send a FP, concentrate the current packet drop NACK of feedback; If there is not packet loss, then do not feed back.The burden of link be can greatly alleviate like this, energy and bandwidth efficiency improved.The value of K can be set by each receiving terminal, and each receiving terminal can be different.In order in time packet drop to be fed back to transmitting terminal, its value can not be excessive, for receiving terminal R
i, with K＜1/P
iBe advisable.
Owing to comprising the ID of packet in the BPH, and packet numbers in order with integer, and therefore, whether receiving terminal can be determined with continuously according to the packet ID that receives does not have packet loss.In a preferred embodiment of the present invention, the detection of described receiving terminal and feedback step can realize by following substep:
Initialization substep A1: preset detected parameters a=0;
Receive substep A2: when receiving a packet, if this packet is the raw data packets of not received, then make a=a+1;
Suspend substep A3: if a＜K then returns receiving step, otherwise, make a=0, and carry out substep A4;
Detect substep A4: whether the ID that judges all packets of receiving is continuous, if, then return substep A2, otherwise, substep A5 carried out;
Feedback substep A5: from all packets of receiving, find packet loss information, and described packet loss information is fed back to transmitting terminal with the form of feedback report.
Similar with receiving terminal, transmitting terminal is not to retransmit once finding that packet loss starts yet.In order to raise the efficiency, we adopt following strategy.After W raw data packets of the every transmission of transmitting terminal, check the feedback report of receiving, the packet that retransmits if necessary just starts coding and retransmits.Similar with receiving terminal, W is unsuitable excessive, unrestrictedly piles up to avoid treating retransmission packet.
Situation under, requirement
In specific implementation, transmitting terminal can be realized based on digital fountain code the re-transmission of described combination bag.So-called digital fountain code refers to that this kind coding can be generated by k original data packet the coding groups of any amount, as long as and the recipient receives wherein arbitrarily m coding groups, can successfully recover whole original data packet with high probability by deciphering.Wherein, k, m are natural number, generally speaking, and m＞k.Above-mentioned cataloged procedure is as the fountain that produces continually water droplet (coding groups) (encoder), and as long as receive the water droplet of sufficient amount with cup (decoder), can reach the purpose of drinking (decoding success).Because unidirectional multicast feedback not, receiving terminal increases for transmitting terminal without any impact, has very strong robustness based on the solution of fountain codes.Therefore, adopt the digital fountain code technology, in a time slot, can retransmit simultaneously a plurality of packets to a plurality of receiving terminals, so retransmission efficiency improves greatly.
Retransmission scheme of the present invention adopts the mode of regularly feeding back to exchange packet drop between transmitting terminal and a plurality of receiving terminal, can when guaranteeing flexibility, reduce signaling consumption and computational complexity as far as possible.
With reference to Fig. 3, show the flow chart of a kind of data repeating method embodiment 2 of the present invention, specifically can comprise:
The difference of this enforcement and embodiment 1 is, transmitting terminal adopts the packet loss matrix to deposit the packet loss information of all receiving terminals, particularly, whenever receives the packet loss information from certain receiving terminal, just described packet loss matrix is upgraded.
In a preferred embodiment of the present invention, the row of described packet loss matrix can corresponding each receiving terminal, the ID that described packet loss matrix column can corresponding each packet, and the initial value of described packet loss matrix can be 0;
Described packet loss information can comprise packet loss ID;
The step of described updating packet loss matrix can comprise:
When the packet loss information that receives from i receiving terminal, according to packet loss ID wherein, successively i is capable in the element corresponding with this packet loss ID put 1, and other element during i is capable sets to 0.
After grasping packet drop, the further work of transmitting terminal is the generation of combination bag.How choosing retransmission data packet may and generating the combination bag is the key point of whole retransmission scheme.
With reference to figure 4, show the radio transmission example of a kind of one-to-many of the present invention.If transmitting terminal S is by M receiving terminal R of radio broadcasting chain road direction
1, R
2..., R
MSend a series of packets, and press sending order numeral 1,2,3 ... these packets are numbered.Owing to reasons such as channel fadings, some packet can not correctly arrive some receiving terminal, and the packet loss phenomenon also namely occurs.Therefore, for the reliability that guarantees to transmit, need transmitting terminal in time to recognize the packet drop of receiving terminal, and carry out necessary re-transmission by transmitting terminal.In the example of Fig. 1, receiving terminal R
1Lost packet 1, receiving terminal R
2Lost packet 3.Notice R
1Correctly received packet 3, and R
2Correctly received packet 1.If each packet is regarded as the vector that is formed by the finite field element, and to do linear combination (for example mould 2 Hes) with the packet 1 and 3 of this vector representation, generate a new combination bag, then broadcast away, so receiving terminal R
1After receiving this combination bag, because R
1Packet 3, R had before been received
1Can utilize packet 3 and combination bag, solution is out from the combination bag by packet 1 that linear transformation will be own required.For example, if make up bag by packet 1 and 3 being made mould 2 and generation, so R
1Only need to do mould 2 Hes to combination bag and packet 3, just can obtain packet 1.In like manner, R
2Also can from the combination bag, solve its required packet 3 with similar mode.As seen, the mode that the present invention adopts this " coding-broadcasting " is only used 1 time slot (time of 1 packet of transmission), and two data packet retransmissions just can will losing are given different receiving terminals, thereby can save to greatest extent system resource.
Can find out from above-mentioned example, the number of data packets that participates in linear combination is not limited to 2, can be individual for 1 (l is＞2 natural number).As long as target receiving terminal R
iKnown l-1 wherein, just can solve according to the mode of above-mentioned linear transformation that bag of oneself losing.If R
iKnown number of data packets is k＜l-1, so R
iCan't solve own missing data bag.According to Gauss theorem, R
iAt least need to receive again l-1-k combination bag (or raw data packets) and just can solve all packet losses.Such R
iThe combination bag that needs to receive is kept in, until can solve the missing data bag.But thus, will certainly take a large amount of memory spaces, and calculating process is very complicated.
For above-mentioned difficulties, for for purpose of brevity, retransmission scheme of the present invention is followed following principle, namely to any receiving terminal R
i, each combination bag contains at most a R
iPacket loss.So just guaranteed R
iWhenever receive a combination bag, as long as this combination bag and R
iPacket loss relevant, R
iCan therefrom solve oneself a packet loss.On this principle basis, packet can be regarded as the vector that is arranged in by 1 and 0, then use 2 yuan of non-zero linear combinations on the territory, namely mould 2 becomes the combination bag with next life.At receiving terminal, can with mould 2 and " cancellation " known packet, solve required packet loss equally.Compare the linear combination on the polynary territory GF (q) (q＞2), mould 2 and obviously simply many.Therefore, in the present invention, can adopt mould 2 and generate and resolve the combination bag.
For satisfying this principle, corresponding above preferred embodiment, step 305 of the present invention can be passed through following substep and realize:
Judge substep B1: judge in the current packet loss matrix whether contain non-zero row, if, then carry out substep B2, otherwise, substep B3 carried out;
Search substep B2: in current packet loss matrix, search the non-zero row of corresponding ID minimum, and the raw data packets that described ID is corresponding is as the combination member;
Find row corresponding to non-zero element in these row, and row corresponding to non-zero element in these row;
Cross out these row and columns, as current packet loss matrix, and return substep B1 with remaining matrix;
Combination substep B3: described combination member is done mould 2 Hes, obtain the combination bag.
For making those skilled in the art understand better the present invention, below take a kind of packet loss matrix of the present invention shown in Figure 5 as example, the course of work of transmitting terminal is described.
This packet loss matrix G
M * NSize be M * N, wherein M is the number of receiving terminal, N is length of window, the capable j column element of its i g
IjExpression, g
Ij=1 expression receiving terminal R
iLost packet D
J+kN(k is 0 or positive integer, and size is determined by residing window phase at that time), otherwise g
Ij=0 explanation explanation R
iCorrectly received D
J+kNSuch packet D
jLoss situation can be by G
M * N(j-1) modN+ 1 row reflect fully.Therefrom also can find out G
M * NThe loss situation that can only show simultaneously at most N bag.The size of N is determined according to actual needs, N should be enough large, so that after j bag send, during and j＞N, the re-transmission (if need retransmit) of j-N bag has successfully been carried out, that is to say window phase must long enough to hold all packet loss information of contemporaneity.
With reference to figure 6, show a kind of transmitting terminal of the present invention retransmits work based on described packet loss matrix flow process, specifically can comprise following:
Step 601, receive the FP from certain receiving terminal, comprise packet loss ID among the described FP;
If contain ID among step 602 FP
j, g then
I ((j-1) modN+1)=1, otherwise g
I ((j-1) modN+1)=0;
Step 603, W raw data packets of every transmission are judged G
M * NIn whether contain non-zero row, if, step 604 then, otherwise, execution in step 607;
Step 604, at G
M * NIn search the non-zero row of corresponding ID minimum, it is j that these row are established its corresponding ID value as the combination member
1, then with IDj
1As the combination member;
Step 605, find row corresponding to non-zero element in these row, and row corresponding to non-zero element in these row;
Suppose
Be total to m
1Individual receiving terminal has been lost
Need to retransmit, then determine j
1Capable i corresponding to non-zero element in the row
1, i
2..., i
M1, and find i
1, i
2..., i
M1Row corresponding to non-zero element in the row;
Step 606, cross out these row and columns, as current packet loss matrix, and return step 603 with remaining matrix;
For example, cross out capable i
1, i
2..., i
M1With the row of correspondence, with remaining matrix as current packet loss matrix.
Step 607, described combination member is made mould 2 and, obtain the combination bag;
Described combination bag can calculate with lower formula:
For example, from G
M * NIn can find out R
1Lost D
1, D
2, D
3Three packets, R
4Lost D
1, D
5Two packets, therefore, we are with the 1st row and the 4th row, and the 1st, 2,3,5 row are from G
M * NIn cross out.In the remaining matrix, the 4th row are non-zero row.Therefore the combination bag that obtains at last:
Step 608, the described combination bag of re-transmission.
In practice, can be combination bag D by the form of Fig. 1
zAdd packet header, and broadcast away.
The present embodiment adopts the packet loss matrix to deposit the packet loss information of all receiving terminals, and follows following strategy according to described packet loss Information generation combination bag the time, namely to any receiving terminal R
i, each combination bag contains at most a R
iPacket loss, therefore can guarantee R
iWhenever receive a combination bag, as long as this combination bag and R
iPacket loss relevant, R
iCan therefrom solve an own required packet loss.
In addition, the present embodiment adopts mould 2 and generates and resolve the combination bag, computing and simple to operate, to hardware and operating system without any specific (special) requirements.When implementing, can be integrated into easily in the various wireless MAC layer protocols, for the broadcast session that reliability requirement is arranged provides service, also can weave into dynamic link library, called when needed by application program.
In actual applications, except raw data packets, the packet that receiving terminal receives also can comprise the combination bag of re-transmission, in this case, receiving terminal can also be decoded to the combination bag of receiving, obtains raw data packets, if this raw data packets exists, then discard processing.
For example, combination bag
Wherein
R
iThe bag of losing, l
mBe the raw data packets number that comprises in this combination bag, then can obtain raw data packets by following mould 2 and computing
Correspondingly, if all packet losses of receiving terminal are all successfully retransmitted, at this moment, can also comprise the re-transmission successful information among the feedback report FP of its transmission, represent with ACK here.Show the form of a kind of feedback report FP of the present invention with reference to figure 7.First byte represents that this FP is ACK or NACK.If n=0 represents that this FP is an ACK; If n＞0 represent that this FP is a NACK, and the current n of a having packet loss needs to retransmit.The back represents respectively the ID of the packet loss that n needs retransmit with the section of n nybble.Therefore, the length of whole FP is 1+4n.
In these cases, when transmitting terminal upgraded the packet loss matrix according to the specifying information among the feedback report FP, the step of described updating packet loss matrix can comprise:
Substep C1, when the feedback report that receives from i receiving terminal, check the content of this feedback report, if packet loss information, then foundation packet loss ID wherein, the element corresponding with this packet loss ID puts 1 in successively i is capable, and other element during i is capable sets to 0;
If substep C2 retransmits successful information, then the element that i is capable all sets to 0.
In addition, in order to realize re-transmission work, each receiving terminal can be safeguarded a buffer queue, so that the raw data packets of receiving is inserted in the formation according to the ID order.In like manner, transmitting terminal also needs a buffer queue, deposits the raw data packets that sent in formation by the ID order.For the sake of simplicity, below deposit packet in formation according to the ID order and become " joining the team ", will delete formation head packet and be called " going out team ".
With reference to figure 8, show in the above-mentioned formation situation, the flow chart of a kind of data repeating method embodiment 3 of the present invention, wherein, the workflow of receiving terminal specifically can comprise:
The first initialization step 801: preset the first detected parameters a=0, i=0, initialization receives buffer queue;
The first receiving step 802: when receiving a packet, if this packet is the raw data packets of not received, then make a=a+1, and this packet is joined the team;
If this packet is the combination bag that retransmits, then described combination bag is decoded, obtain raw data packets, if this raw data packets exists, discard processing then, otherwise, this raw data packets is inserted formation;
Pause step 803: if a＜K then returns step 802, otherwise, make a=0, and execution in step 804;
Detecting step 804: check from the beginning to the end the packet in the buffer queue, if it is discontinuous to be checked through packet ID, then make i=1, then carry out substep 851;
If it is continuous to be checked through packet ID, and i=1, then makes i=0, and carry out substep 852;
If it is continuous to be checked through packet ID, and i=0, then returns first and accept step 802.
Feedback step 805:
The first feedback substep 851: find packet loss information in all packets from buffer queue, and described packet loss information is fed back to transmitting terminal with the form of NACK;
The second feedback substep 852: to the transmitting terminal feeding back ACK;
Correspondingly, the workflow of transmitting terminal can realize by following steps:
The second initialization step 806, preset the second detected parameters a '=0, initialization sends buffer queue, sets up packet loss matrix G
M * N, its element initial value is 0;
Send substep 871, send a raw data packets, make a '=a '+1, and this packet is joined the team, if a '＜W, then repeating step 871, otherwise, make a '=0, execution in step 808;
Reception is from R
iFP;
If this FP is ACK, then with G
M * NI capablely all set to 0; If this FP is NACK, and contain IDj, then g among the NACK
I ((j-1) modN+1)=1, otherwise g
I ((j-1) modN+1)=0;
If G
M * NJ row are full 0 row, establish this row corresponding data bag D
J+kNIf all row of corresponding data bag ID＜j+kN are full 0 row, then D so
J+kNAll data contract out team before;
Check step 808, check G
M * N, the bag that retransmits if necessary, then the described method of Fig. 6 generates the combination bag and broadcasts away;
Cleanup step 809: check to send length of buffer queue, if length Q＞T then deletes Q-T bag of formation head.
In practice, transmitting terminal also needs the useless bag in the periodic cleaning transmission buffer queue, in order to avoid when not receiving FP for a long time, it is long that buffer queue becomes.Here the strategy that adopts is that W packet inspection of every transmission be length of buffer queue once, deletes in case of necessity some bags of formation head, so that queue length is always less than or equal to a set point T.The large I of T is set according to actual conditions, requires T＞N can both correctly to be retransmitted to guarantee all packet losses.
In above implementation, have several problems should be noted that:
1) in BPH and FP, all represent a packet ID with 4 bytes, send like this after 4294967295 bags, ID can overflow.The way of reply is when overflowing, and again is set to 0 ID number.
2) among the BPH with the length of 2 byte representation packets, this requires the length of each packet can not be greater than 65535.In order to control packet loss, the bag of wireless transmission is long generally can both to be met this requirement.
3) the same with transmitting terminal, receiving terminal also needs useless bag in the periodic cleaning buffer queue to save the space.Because receiving terminal may receive the combination bag, the packet that must preserve some in the buffer queue is used for decoding.Receiving terminal can judge that by the BPH that receives which bag is expired.If j
MinThe minimum ID that BPH comprises, namely
According to the generative process of combination bag, can conclude that all ID are less than j so
MinPacket all by all R
iThe correct reception can these packets not occur in the combination bag of sending out later on again, therefore, just can go out team yet.
With reference to figure 9, show the structure chart of a kind of data re-transmission system embodiment of the present invention, specifically can comprise:
Detect and feedback module 901, be used for whenever receiving K raw data packets, carry out packet loss detection, and when detecting packet loss, send feedback report to transmitting terminal, described feedback report comprises the packet loss information of this receiving terminal, and K is natural number;
Owing to comprising the ID of packet in the BPH, and packet is with whole several numbering in order, and therefore, whether receiving terminal can be determined with continuously according to the packet ID that receives does not have packet loss.In a preferred embodiment of the present invention, described detection and feedback module can comprise:
The first receiving element 912 is used for if this packet is the raw data packets of not received, then making a=a+1 when receiving a packet;
Suspend unit 913, be used for when a＜K, returning the first receiving element, otherwise, make a=0, and carry out detecting unit;
Detecting unit 914 is used for judging whether the ID of all packets of receiving is continuous, if, then return the first receiving element, otherwise, feedback unit carried out;
In specific implementation, described detection and feedback module 801 can be positioned at receiving terminal inside, also can be used as one independently module be positioned at outside the receiving terminal, the present invention is not limited this.
Combination bag generation module 902 is used for W raw data packets of every transmission, according to the packet loss information of all receiving terminals that receive, by network code, generates the combination bag, and W is natural number;
In another kind of preferred embodiment of the present invention, adopt the packet loss matrix to deposit the packet loss information of all receiving terminals, therefore, described system can also comprise:
Set up module 904, be used for setting up the packet loss matrix, described packet loss matrix is used for depositing the packet loss information of all receiving terminals;
In this case, described combination bag generation module 902 can comprise:
The second receiving element 921 is used for receiving the packet loss information from certain receiving terminal;
Updating block 922 is used for according to described packet loss information described packet loss matrix being upgraded;
In specific implementation, described module 902-904 can be positioned at transmitting terminal inside, also can be used as one independently module be positioned at outside the receiving terminal, the present invention is not limited this.
In actual applications, except raw data packets, the packet that receiving terminal receives also can comprise the combination bag of re-transmission, and in this case, described system can also comprise:
Each embodiment in this specification all adopts the mode of going forward one by one to describe, and what each embodiment stressed is and the difference of other embodiment that identical similar part is mutually referring to getting final product between each embodiment.For device embodiment because itself and embodiment of the method basic simlarity, so describe fairly simple, relevant part gets final product referring to the part explanation of embodiment of the method.
Above to a kind of data repeating method provided by the present invention and a kind of data re-transmission system, be described in detail, used specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.
Claims (10)
1. a data repeating method is characterized in that, comprising:
Set up the packet loss matrix, described packet loss matrix is used for depositing the packet loss information of all receiving terminals;
Described packet loss information comprises packet loss ID; Corresponding each receiving terminal of the row of described packet loss matrix, the ID of corresponding each packet of described packet loss matrix column, the initial value of described packet loss matrix is 0;
Whenever receive K raw data packets, receiving terminal carries out packet loss detection, and when detecting packet loss, sends feedback report to transmitting terminal, and described feedback report comprises the packet loss information of this receiving terminal, and K is natural number;
W raw data packets of every transmission, transmitting terminal by network code, generate the combination bag according to the packet loss information of all receiving terminals that receive, and W is natural number; Described according to packet loss information in the packet loss matrix, by network code, the step that generates the combination bag comprises:
Determining step: judge in the current packet loss matrix whether contain non-zero row, if, then carry out finding step, otherwise, combination step carried out;
Finding step: in current packet loss matrix, search the non-zero row of corresponding ID minimum, and the raw data packets that described ID is corresponding is as the combination member;
Find row corresponding to non-zero element in these row, and row corresponding to non-zero element in these row;
Cross out these row and columns, as current packet loss matrix, and return determining step with remaining matrix;
Combination step: described combination member is done mould 2 Hes, obtain the combination bag;
Transmitting terminal retransmits described combination bag.
2. the method for claim 1 is characterized in that, also comprises:
The step of described generation combination bag comprises:
Reception is from the packet loss information of certain receiving terminal;
According to described packet loss information described packet loss matrix is upgraded;
W raw data packets of every transmission detects described packet loss matrix, and when detecting packet loss information, according to described packet loss information, by network code, generates the combination bag.
3. method as claimed in claim 2 is characterized in that,
The step of described updating packet loss matrix comprises:
When the packet loss information that receives from i receiving terminal, according to packet loss ID wherein, successively i is capable in the element corresponding with this packet loss ID put 1, and other element during i is capable sets to 0.
4. the method for claim 1 is characterized in that, also comprises: receiving terminal is decoded to the combination bag of receiving, obtains raw data packets, if this raw data packets exists, and discard processing then.
5. method as claimed in claim 3 is characterized in that, described feedback report also comprises the re-transmission successful information;
The step of described updating packet loss matrix comprises:
When the feedback report that receives from i receiving terminal, check the content of this feedback report, if packet loss information, then according to wherein packet loss ID, successively i is capable in the element corresponding with this packet loss ID put 1, and other element during i is capable sets to 0;
If the re-transmission successful information, then the element that i is capable all sets to 0.
6. the method for claim 1 is characterized in that, describedly whenever receives K raw data packets, and receiving terminal carries out packet loss detection, and when detecting packet loss, the step that sends feedback report to transmitting terminal comprises:
Initialization step: preset detected parameters a=0;
Receiving step: when receiving a packet, if this packet is the raw data packets of not received, then make a=a+1;
Pause step: if a＜K then returns receiving step, otherwise, make a=0, and carry out detecting step;
Detecting step: whether the ID that judges all packets of receiving is continuous, if, then return receiving step, otherwise, feedback step carried out;
Feedback step: from all packets of receiving, find packet loss information, and described packet loss information is fed back to transmitting terminal with the form of feedback report.
7. a data re-transmission system is characterized in that, comprising:
Set up module, be used for setting up the packet loss matrix, described packet loss matrix is used for depositing the packet loss information of all receiving terminals; Described packet loss information comprises packet loss ID; Corresponding each receiving terminal of the row of described packet loss matrix, the ID of corresponding each packet of described packet loss matrix column, the initial value of described packet loss matrix is 0;
Detect and feedback module, be used for whenever receiving K raw data packets, carry out packet loss detection, and when detecting packet loss, send feedback report to transmitting terminal, described feedback report comprises the packet loss information of this receiving terminal, and K is natural number;
Combination bag generation module is used for W raw data packets of every transmission, according to the packet loss information of all receiving terminals that receive, by network code, generates the combination bag, and W is natural number;
Specifically comprise: judge in the current packet loss matrix whether contain non-zero row, if then in current packet loss matrix, search the non-zero row of corresponding ID minimum, and the raw data packets that described ID is corresponding is as the combination member; Find row corresponding to non-zero element in these row, and row corresponding to non-zero element in these row; Cross out these row and columns,, and continue to judge as current packet loss matrix with remaining matrix, otherwise, described combination member is done mould 2 He, obtain making up and wrap;
Retransmission module is used for retransmitting described combination bag.
8. system as claimed in claim 7 is characterized in that, also comprises:
Described combination bag generation module comprises:
The second receiving element is used for receiving the packet loss information from certain receiving terminal;
Updating block is used for according to described packet loss information described packet loss matrix being upgraded;
Assembled unit is used for W raw data packets of every transmission, described packet loss matrix is detected, and when detecting packet loss information, according to the packet loss information in the described packet loss matrix, by network code, generate the combination bag.
9. system as claimed in claim 7 is characterized in that, also comprises:
Decoder module is used for the combination bag of receiving is decoded, and obtains raw data packets, if this raw data packets exists, and discard processing then.
10. system as claimed in claim 7 is characterized in that, described detection and feedback module comprise:
Initialization unit is used for presetting detected parameters a=0;
The first receiving element is used for if this packet is the raw data packets of not received, then making a=a+1 when receiving a packet;
Suspend the unit, be used for when a＜K, returning the first receiving element, otherwise, make a=0, and carry out detecting unit;
Detecting unit is used for judging whether the ID of all packets of receiving is continuous, if, then return the first receiving element, otherwise, feedback unit carried out;
Feedback unit is used for finding packet loss information from all packets of receiving, and described packet loss information is fed back to transmitting terminal with the form of feedback report.
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