CN102694632A - Deep space file transfer method based on relay store-forward - Google Patents

Abstract

The invention provides a deep space file transfer method based on relay store-forward, used for transmitting a file to a receiving terminal from a transmitting terminal by virtue of a relay satellite. The deep space file transfer method based on relay store-forward comprises a transmitting terminal-to- relay satellite stage and a relay satellite-to-receiving terminal stage... According to the deep space file transfer method based on relay store-forward disclosed by the invention, in a high-error-rate deep space environment, gain of a delay negative acknowledgement type CFDP (ccsds file delivery protocol) based on the relay store-forward is increased by dozens to hundreds of astronomical units compared with the traditional point-to-point direct transfer protocol scheme, relay amplification forward protocol scheme and relay decoding forward protocol scheme in the aspect of transmission delay index.

Description

Method for transmitting deep space file based on relaying storage-forwarding

Technical field

The present invention relates to a kind of method for transmitting deep space file based on relaying storage-forwarding.

Background technology

Existing deep space communication FTP mainly contains two types according to the difference of retransmission mechanism:

1) ICP/IP protocol

Under internet (Internet) background; With what set up under the assumed conditions such as infinitely great, the low delay of bandwidth, low error rate, continuous communiction; The TCP establishment of connection need send both sides and pass through hand shaking earlier; Promptly formally beginning the file data transmission need carry out once coming and going propagating at least; Transmission Control Protocol uses the hierarchical routing agreement of calculating based on real-time status; Autonomous system is carried out addressing need pass through Border Gateway Protocol (BGP), then passes through IS2IS (Intermediate System to Intermediate System), OSPF (Open ShortestPath First) and EIGRP Routing Protocol addressing such as (Enhanced Interior Gateway Routing Protocol) in internal system.Characteristics are can internet, seamless compatible ground.

2) FTP of spatial data Advisory Board (CFD P, CCSDS File DeliveryProtocol)

CFDP produces under the TCP/IP background that service efficiency is lower in spatial network communication.Than TCP/IP; CFDP has overcome TCP/IP application layer protocol File Transfer Protocol and can't support multi-link transmission, transmission to suspend and continuous deficiency and ICP/IP protocol " handshake mechanism " the inefficient shortcoming in space communication that passes, tolerates the incorrect order bag; Part has solved space communication file reliable transmission problem end to end, is widely used in the space science tasks such as the moon, mars exploration plan.Four kinds of patterns that CCSDS has been the CFDP protocol definition: NAK CFDP agreement immediately, asynchronous NAK CFDP agreement triggers NAK CFDP agreement and time-delay NAK CFDP agreement.The characteristics of CFDP agreement are to adopt ACK and NAK to mix acknowledgement mechanism.When protocol Data Unit (PDU:Protocol Data Unit) transmission makes a mistake, receiving terminal feedback NACK response message (NAK).And confirm that response message (ACK) only is used for control data and wraps in the mutual of transmitting-receiving two-end, generally when tail of file and transmission course end, occur.

Deep space communication and traditional ground communication have huge difference, its peculiar dynamic long delay, high bit-error, are interrupted characteristics such as available link, dissymmetrical channel, make ICP/IP protocol be applied directly in the deep space communication system and a lot of problems can occur.At first, propagation delay is huge in the deep space communication, for example Mars to the round-trip delay of the earth according to the orbital position difference of celestial body usually between 8.5 to 40 minutes, if round-trip delay greater than communication duration, application data does not have the chance of transmission at all so.Secondly, up very big with the asymmetric throughput influence of information rate down link to TCP.Estimated that an accessible ground month communication upstream rate was 4kb/s in 2015, downstream rate is 10Mb/s, and Mars communication upstream rate is 4kb/s, and downstream rate is 4～6Mb/s.Because the asymmetric meeting of channel speed causes bigger wire rate burst error, it is congested to increase the weight of down buffer storage, and throughput decays with the asymmetry exponentially.Once more, the congested strategy with loss of data of Transmission Control Protocol resolution determines the deterioration rapidly with the increase that comes and goes propagation delay and information dropout probability of its throughput.Transmission Control Protocol guarantees to send in order fileinfo through ARQ mechanism, and arbitrary packet of losing will cause that all data after this packet resend.The error rate of deep space channel (BER) is bigger than the error rate of terrestrial channel usually, and the typical deep space communication error rate is 10 ^-5, and since the celestial body orbital motion to the blocking of detector, the deep space communication link can produce periodic interruptions.In addition, the error detection occurs of Transmission Control Protocol and recovery policy are not suitable for deep space high bit-error environment: at first, Transmission Control Protocol overflows through the retransmission timer timing to be judged losing of packet; Secondly, the reason that Transmission Control Protocol can't be distinguished data-bag lost is network congestion or channel error code, and Transmission Control Protocol is mainly handled error code through reducing message transmitting spped rate to avoid congested strategy.In addition, throughput can be along with the further deterioration of losing of confirming response message (ACK, Acknowledgement Character).Because Transmission Control Protocol is based on the agreement of end-to-end re-transmission, buffer memory is only confirmed just can discharge the communication resource that is used to retransmit after correct all information of reception to transmitting terminal at receiving terminal; The informational needs that transmission course is lost retransmits, and further prolongs the time of resource occupation buffer memory, is not suitable for for spatial cache and the limited deep space probe of disposal ability.And the Routing Protocol of TCP/IP lacks foresight for following possible route of deep space communication operating environment.In addition, the deep space communication environment is difficult to the time interval is made accurate prediction, therefore the very sensitive distributed routing algorithm of the forecasting accuracy in the state information updating time interval is not suitable for.

Be faced with formidable challenges on the problems such as to sum up, existing ICP/IP protocol system is long at the propagation delay of deep space communication, the error rate is high, asymmetric link, link compatibility and heterogeneous network.At chain-circuit time delay or the bigger deep space network of time delay bandwidth product, various TCP improve agreement and are more or less the same and poor performance, can not satisfy the mission requirements of deep space file high efficiency of transmission.

Although than ICP/IP protocol, the feedback mechanism efficient of CFDP is significantly improved, in order to ensure reliable transmission; CFDP still need feed back repeatedly NAK and a small amount of ACK information; And the continuous increase of transmission range has increased this mutual round-trip delay, has reduced the efficiency of transmission of CFDP.Particularly, the channel bit error rate inclement condition can cause data-bag lost quantity to increase, and has increased the number of times that the file feedback retransmits, thereby has increased the required time of file reliable transmission.For example: when the error rate near 10 ^-4The time, the simulation curve of the CFDP file transfer time delay expectation of the mode that direct transfers shows its performance severe exacerbation.It is very big that frequent re-transmission under the deep space long time delay environment make to come and go propagation delay total propagation delay time in whole document transmission process, especially in the earth-Mars communication average single propagation delay near 20 minutes.

Summary of the invention

In order to overcome the deficiency of above-mentioned prior art; The present invention provides a kind of method for transmitting deep space file; Be used for file is sent to receiving terminal by transmitting terminal through the relaying star, said method for transmitting deep space file based on relaying storage-forwarding comprises transmitting terminal to relaying star stage and relaying star to receiving terminal stage

Transmitting terminal to the relaying star stage further may further comprise the steps:

Step (a), transmitting terminal send comprise MPDU, EOF all PDU to the relaying star, send at transmitting terminal that the relaying star does not return any NAK or ACK information in the process of PDU, transmitting terminal sends out and gets into step (b) after all PDU and relaying star are received EOF;

Step (b), relaying star constantly return NAK information and have received that up to the relaying star relaying star returns FIN to transmitting terminal after all PDU of whole file, relaying star have received all PDU of whole file, and the relaying star finishes transmission course and also closes link;

Relaying star to the receiving terminal stage further may further comprise the steps:

Step (c), relaying star send all PDU to transmitting terminal; In step (c); After the EOF that relaying magnitude end to be sent sends arrives, send paid-in whole PDU to receiving terminal, promptly said step (c) starts from the moment that the step (a) of transmitting terminal to relaying star in the stage finishes;

Return NAK to the relaying star after the integrality of step (d), receiving terminal detection file, require the relaying star that the PDU of disappearance is retransmitted;

Step (e), relaying star are accepted the NAK that receiving terminal returns, and the retransmission list of the PDU of required re-transmission is checked and confirmed to the relaying star;

Step (f), the affirmation of relaying star need the PDU that retransmits whether to be retransmitted to the relaying star by transmitting terminal, and the relaying star will be sent to the relaying star by transmitting terminal and the PDU in the retransmission list of PDU is sent to receiving terminal; In this step; The relaying star will not waited for after all PDU that need transmitting terminal to retransmit all arrive and begin to retransmit again; Received and the PDU in retransmission list but retransmit immediately unreceived PDU waits for the NAK of next receiving terminal checks whether can retransmit when arriving again.

Step (g), repeating step (d) are received all PDU of file to (f) up to receiving terminal;

Step (h), receiving terminal return FIN to the relaying star, and the relaying star is received FIN and return ACK (FIN) to receiving terminal that receiving terminal is accepted ACK (FIN) and closed link, ends file transfer.

Of the present inventionly further be improved to, said transmitting terminal to relaying star adopts time-delay NACK type CFDP protocol transmission algorithm to carry out transfer of data in the stage.

Of the present inventionly further be improved to, said transmitting terminal to the distance of relaying star smaller or equal to the distance of relaying star to receiving terminal.

Of the present inventionly further be improved to, said method for transmitting deep space file based on relaying storage-forwarding satisfies following formula,

$T_{\mathrm{def}2}=\frac{[E\left(M\right)-1](2{\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}+T_{\mathrm{NAK}})}{1-{\mathrm{<figure-callout\; id="2"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}+\frac{{\mathrm{NT}}_{\mathrm{PDU}}(\frac{1}{1-P_{\mathrm{ePDU}2}}-1)}{1-P_{\mathrm{eNAK}2}}---\left(10\right)$

Wherein: $E\left(M\right)=1+\underset{m-1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}[1-{(1-P_{\mathrm{EPDU}2}^m)}^N]$

T _Def2For the relaying star in the file transfer of receiving terminal the relaying star in all PDU retransmission processes to the spatial transmission time delay sum of receiving terminal and the processing delay sum of giving out a contract for a project when retransmitting; T _Prop2Be the propagation delay of relaying star to receiving terminal; T _NAKThe time delay of giving out a contract for a project for NAK; P _ENAK2Be the packet loss of relaying star to receiving terminal section NAK; N is the number of PDU; T _PDUThe time delay of giving out a contract for a project for PDU; P _EPDU2Be the packet loss of relaying star to receiving terminal section PDU; P _ENAK2Be the packet loss of relaying star to receiving terminal section NAK; E (M) is the expectation of M, wherein being defined as of M: suppose K _iThe number of times of transmission altogether when being i PDU transmission success makes that M is the number of transmissions of the maximum PDU of number of retransmissions, and then M is max{K ₁, K ₂, K ₃...,, then M-1 is total number of retransmissions.

Of the present inventionly further be improved to, said transmitting terminal to the distance of relaying star greater than the distance of relaying star to receiving terminal.

Of the present inventionly further be improved to, said method for transmitting deep space file based on relaying storage-forwarding satisfies following formula,

${\mathrm{<figure-callout\; id="2"\; label="T\; inc"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{inc}}+T_{\mathrm{def}2}=T_{\mathrm{def}1}+\frac{{\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}}{1-{\mathrm{<figure-callout\; id="2"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}$

$=\frac{[E\left(M\right)-1]({2\mathrm{<figure-callout\; id="1"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}+T_{\mathrm{NAK}})}{1-{\mathrm{<figure-callout\; id="1"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}+\frac{{\mathrm{NT}}_{\mathrm{PDU}}(\frac{1}{1-P_{\mathrm{ePDU}1}}-1)}{1-{\mathrm{<figure-callout\; id="1"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}}{1+{\mathrm{<figure-callout\; id="2"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}$

Wherein: $E\left(M\right)=1+\underset{m-1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}[1-{(1-P_{\mathrm{EPDU}2}^m)}^N]$

T _Inc1Processing delay and transmitting terminal the spatial transmission time delay of giving out a contract for a project for all packets of transmitting terminal to the relaying star; T _Inc2For sending processing delay and relaying star the spatial transmission time delay of giving out a contract for a project of all packets that the relaying star receives at this moment to receiving terminal; T _Def2For the relaying star in the file transfer of receiving terminal the relaying star in all PDU retransmission processes to the spatial transmission time delay sum of receiving terminal and the processing delay sum of giving out a contract for a project when retransmitting; T _Prop1Be the propagation delay of transmitting terminal to the relaying star; T _NAKThe time delay of giving out a contract for a project for NAK; N is the number of PDU; T _PDUThe time delay of giving out a contract for a project for PDU; P _EPDU1Be the packet loss of transmitting terminal to relaying star section PDU; P _ENAK1Be the packet loss of transmitting terminal to relaying star section NAK; T _Prop2Be the propagation delay of relaying star to receiving terminal; P _ENAK2Be the packet loss of relaying star to receiving terminal section NAK; N is the number of PDU; E (M) is the expectation of M, wherein being defined as of M: suppose K _iThe number of times of transmission altogether when being i PDU transmission success makes that M is the number of transmissions of the maximum PDU of number of retransmissions, and then M is max{K ₁, K ₂, K ₃...,, then M-1 is total number of retransmissions.

Compared to prior art; Method for transmitting deep space file based on relaying storage-forwarding of the present invention is under the deep space environment of high bit-error, and the time-delay NACK type CFDP agreement that storage is transmitted based on the relaying more traditional direct host-host protocol scheme of point-to-point, relaying on the propagation delay time index amplifies the retransmission protocol scheme and relaying decoding retransmission protocol scheme has obtained tens to hundreds of a.u gains.

Description of drawings

Fig. 1 is the method for transmitting deep space file transmission course sketch map that the present invention is based on relaying storage-forwarding

Fig. 2 is the d that the present invention is based on the method for transmitting deep space file of relaying storage-forwarding ₁Smaller or equal to d ₂The time the transmission course sketch map

Fig. 3 is the d that the present invention is based on the method for transmitting deep space file of relaying storage-forwarding ₁Greater than d ₂The time the transmission course sketch map

Fig. 4 the present invention is based on the situation contrast sketch map that the delay performance of four kinds of transmission plans of the method for transmitting deep space file of relaying storage-forwarding changes with bit error rate

Fig. 5 the present invention is based on the situation contrast sketch map that the delay performance of four kinds of transmission plans of the method for transmitting deep space file of relaying storage-forwarding changes with transmission rate

Fig. 6 the present invention is based on the delay performance of four kinds of transmission plans of method for transmitting deep space file of relaying storage-forwarding with the situation of the length variations of PDU contrast sketch map

Fig. 7 the present invention is based on the situation contrast sketch map that the delay performance of four kinds of transmission plans of the method for transmitting deep space file of relaying storage-forwarding changes with the number of PDU

Embodiment

Below in conjunction with description of drawings and embodiment the present invention is further specified.

See also Fig. 1 to Fig. 3, the invention provides a kind of method for transmitting deep space file based on relaying storage-forwarding.

As shown in Figure 1; Method for transmitting deep space file based on relaying storage-forwarding of the present invention is used for file is sent to receiving terminal by transmitting terminal through the relaying star, and the method for transmitting deep space file based on relaying storage-forwarding of the present invention comprises transmitting terminal to relaying star stage and relaying star to receiving terminal stage.

Transmitting terminal to the relaying star stage further may further comprise the steps:

Step (a), transmitting terminal send and comprise MPDU (Meta-data Protocol Data Unit; The metadata protocol data cell), EOF (End Of File; EOF) at interior all PDU (Protocol DataUnit; Protocol Data Unit) to the relaying star, the relaying star does not return any NAK (Negative Acknowledge confirms response message) or ACK (AcknowledgementCharacter in the process of transmitting terminal transmission PDU; Confirm response message) information, transmitting terminal sends out and gets into step (b) after all PDU and relaying star are received EOF;

Step (b), relaying star constantly return NAK information has been received whole file up to the relaying star all PDU; The relaying star returned FIN (finish after the relaying star had been received all PDU of whole file; END instruction) to transmitting terminal, the relaying star finishes transmission course and closes link;

Adopt time-delay NACK type CFDP protocol transmission algorithm to carry out transfer of data in stage at transmitting terminal to relaying star.

Relaying star to the receiving terminal stage further may further comprise the steps:

Step (c), relaying star send all PDU to transmitting terminal; In step (c); After the EOF that relaying magnitude end to be sent sends arrives, send paid-in whole PDU to receiving terminal, promptly said step (c) starts from the moment that the step (a) of transmitting terminal to relaying star in the stage finishes;

Return NAK to the relaying star after the integrality of step (d), receiving terminal detection file, require the relaying star that the PDU of disappearance is retransmitted;

Step (e), relaying star are accepted the NAK that receiving terminal returns, and the retransmission list of the PDU of required re-transmission is checked and confirmed to the relaying star;

Step (f), the affirmation of relaying star need the PDU that retransmits whether to be retransmitted to the relaying star by transmitting terminal, and the relaying star will be sent to the relaying star by transmitting terminal and the PDU in the retransmission list of PDU is sent to receiving terminal; In this step; The relaying star will not waited for after all PDU that need transmitting terminal to retransmit all arrive and begin to retransmit again; Received and the PDU in retransmission list but retransmit immediately unreceived PDU waits for the NAK of next receiving terminal checks whether can retransmit when arriving again.

Step (g), repeating step (d) are received all PDU of file to (f) up to receiving terminal;

Step (h), receiving terminal return FIN to the relaying star, and the relaying star is received FIN and return ACK (FIN) (affirmation termination character) to receiving terminal that receiving terminal is accepted ACK (FIN) and closed link, ends file transfer.

In conjunction with the mission requirements of deep space communication, the present invention realizes that with file the required time delay of reliable transmission is as performance index.In the present invention, step (a) is T _Inc1Transmission detection-phase I, step (b) is T _Ddef1Time-delay detection-phase I, step (c) is T _Inc2Transmission detection-phase II, step (d) to step (h) is T _Def2Time-delay detection-phase II.As shown in Figure 1, adopt the file transfer time delay of RSF-CFDP agreement can be divided into three parts: transmitting terminal is to the T of relaying star _Inc1Section transmission course time delay, relaying star are to the T of receiving terminal _Inc2With T _Def2Two sections transmission course time delays.Be overall delay T=T _Inc1+ T _Inc2+ T _Def2T _Inc1The propagation delay time of section comprises that give out a contract for a project processing delay and transmitting terminal of all packets of transmitting terminal are to the spatial transmission time delay of relaying star, T _Inc2The file transfer time delay of section comprises that give out a contract for a project processing delay and the relaying star that send all packets that the relaying star receives at this moment are to the spatial transmission time delay of receiving terminal, T _Def2Comprise the relaying star in the file transfer of receiving terminal the relaying star in all PDU retransmission processes to the spatial transmission time delay sum of receiving terminal and the processing delay sum of giving out a contract for a project when retransmitting.

A) T _Inc1The time delay modeling of section

If N represent the number of the PDU that will send, T _PDUFor sending needed time of single PDU, P _EPDU1Be the packet loss of transmitting terminal to the via node section, T _Prop1Be the one way transmission time of transmitting terminal to the relaying star, T _{ACK1 (EOF)}For transmitting terminal sends required time of ACK (EOF), T _EOF1For transmitting terminal sends the required time of EOF.Transmitting terminal is to the T of relaying star transmission course _Inc1Duan Shiyan is following:

B) T _Inc2The time delay modeling of section

Transmission course by RSF-CFDP can be known T _Inc2With T _Inc1Derivation principle is similar, T _PDUFor sending needed time of single PDU, P _EPDU2Be the packet loss of via node section to receiving terminal, T _Prop2Be the one way transmission time of relaying star to receiving terminal, T _{ACK2 (EOF)}For the relaying star sends required time of ACK (EOF), T _EOF2For the relaying star sends the required time of EOF.Difference is that variation has taken place parameter N.Definition of T _Inc2In this parameter be N ₂, N ₂Following with the relation of N:

N ₂＝N(1-P _ePDU1) (2)

The relaying star is to the T of receiving terminal transmission course _Inc2Duan Shiyan can be expressed as:

${\mathrm{<figure-callout\; id="2"\; label="T\; inc"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{inc}}=N_2{T}_{\mathrm{PDU}}+\frac{P_{\mathrm{ePDU}2}({2\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}+{\mathrm{<figure-callout\; id="2"\; label="T\; EOF"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{EOF}}+T_{\mathrm{ACK}2\left(\mathrm{EOF}\right)})}{1+{\mathrm{<figure-callout\; id="2"\; label="P\; ePDU"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{ePDU}}}+{\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}+{\mathrm{<figure-callout\; id="2"\; label="T\; EOF"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{EOF}}+T_{\mathrm{ACK}2\left(\mathrm{EOF}\right)}---\left(3\right)$

T _Inc1The propagation delay time of section comprises that give out a contract for a project processing delay and transmitting terminal of all packets of transmitting terminal are to the spatial transmission time delay of relaying star, T _Inc2The file transfer time delay of section comprises that give out a contract for a project processing delay and the relaying star that send all packets that the relaying star receives at this moment are to the spatial transmission time delay of receiving terminal, T _Def2Comprise the relaying star in the file transfer of receiving terminal the relaying star in all PDU retransmission processes to the spatial transmission time delay sum of receiving terminal and the processing delay sum of giving out a contract for a project when retransmitting, T _Prop1Be the propagation delay of transmitting terminal to the relaying star, T _Prop2Be the propagation delay of relaying star to receiving terminal, P _EPDU1Be the packet loss of transmitting terminal to relaying star section PDU, P _EPDU2Be the packet loss of relaying star to receiving terminal section PDU, P _ENAK1Be the packet loss of transmitting terminal to relaying star section NAK, P _ENAK2Be the packet loss of relaying star to receiving terminal section NAK, T _NAKBe the time delay of giving out a contract for a project of NAK, T _PDUBe the time delay of giving out a contract for a project of PDU, N is the number of PDU, and E (M) is the expectation of M, wherein being defined as of M: suppose K _iThe number of times of transmission altogether when being i PDU transmission success makes that M is the number of transmissions of the maximum PDU of number of retransmissions, and then M is max{K ₁, K ₂, K ₃....So, M-1 is total number of retransmissions.

C) T _Def2The time delay modeling of section

T _Def2Be retransmission delay time, be defined as and send first NAK from the recipient and begin for the relaying star, to all PDU successful required time till the transmission all.For the ease of analyzing, it is divided into two kinds of situation considers.In order to divide both of these case, at first, we are to introducing before and after the relaying star, and the diverse location of relaying star chooses, and concrete analysis is carried out in the influence of link error rates, provide segmentation error rate P under the via node condition of diverse location _E1, P _E2With omnidistance error rate P _eRelation.We define transmitting terminal respectively is d to the distance of relaying star ₁, whole range distance is d, different d ₁Represent different via node positions.

At first, it is following to provide the deep space link parameter expression formula of standard:

$\frac{{\mathrm{<figure-callout\; id="0"\; label="E\; b\; N"\; filenames="120604100349.png,120604100400.png"\; state="\{\{state\}\}">E</figure-callout>}}_b}{N_{}}=P_{\mathrm{sc}}\&CenterDot;\frac{G_{\mathrm{sc}}}{L_{\mathrm{psc}}}\&CenterDot;\frac{1}{L_{\mathrm{space}}}\&CenterDot;\frac{1}{L_{\mathrm{pg}}}\&CenterDot;\frac{1}{K}\&CenterDot;\frac{G_g}{L_{\mathrm{atm}}\&CenterDot;(T_B+T_{\mathrm{eq}})}\&CenterDot;\frac{1}{L_{\mathrm{sys}}}\&CenterDot;\frac{1}{R_b}---\left(4\right)$

Wherein, E _b/ N ₀Be the bit signal to noise ratio (snr) of deep space link, parameter E _b, N ₀, P _Sc, G _Sc, L _Psc, L _Space, L _Pg, K, G _g, L _Atm, T _B, T _Eq, L _SysAnd R _bThe energy of representing every Bit data that receiving terminal receives respectively; The single face noise power spectral density, the radio-frequency power of spacecraft or relaying star emission data, the antenna gain of spacecraft or relaying star; The sensing loss of spacecraft or relaying star antenna; Free space path loss, atmospheric loss, Boltzmann constant (1.38x10 ^-23J/K), the earth station antenna gain, ground station points to loss, sky brightness noise temperature, ground installation noise temperature, other all system losses, and information rate (bits/sec).Other parameter constants are apart from variable d ₁Variation can cause the space path loss L of segmentation _SpaceVariation, and then cause the variation of segment link signal to noise ratio, the BPSK modulation relation of link bit signal to noise ratio (snr) and link bit error rate (BER) down is following.

SNR＝10lgP _sc+10lgG _sc+10lgG _g-10lgL _psc-(32.44+20lgd+20lgf)

(5)

-10lgL _pg-10lgK-10lgL _atm-10lg(T _B+T _eq)-10lgL _sys-10lgR _b

$P_e={\&Integral;}_{-\&infin;}^0\frac{1}{\sqrt{2\mathrm{\&pi;}}{\mathrm{\&sigma;}}_n}{e}^{-{(x-\mathrm{\&mu;})}^2/2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="120604100400.png"\; state="\{\{state\}\}">n</figure-callout>}}^2}\mathrm{dx}=\frac{1}{2}\&times;\mathrm{erfc}\left(\sqrt{\mathrm{SNR}}\right)---\left(6\right)$

From equality (4), (5), (6); We can find out that Distance Transmission distance and bit error rate are the relations of shining upon one by one; We suppose to have identical and enough transmitting powers at sending node with the relaying star earlier; Obtain the variable quantity of signal to noise ratio through the variable quantity of distance,, derive the bit error rate expression formula after the variable in distance then based on the error rate before the variable in distance.

SNR ₀＝(erfc ^-1(2□P _e) ² (7)

${\mathrm{<figure-callout\; id="1"\; label="P\; e"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_e={\&Integral;}_{-\&infin;}^0\frac{1}{\sqrt{2\mathrm{\&pi;}}{\mathrm{\&sigma;}}_n}{e}^{-{(x-\mathrm{\&mu;})}^2/2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="120604100400.png"\; state="\{\{state\}\}">n</figure-callout>}}^2}=\frac{1}{2}\&times;\mathrm{erfc}\left(\sqrt{{\mathrm{SNR}}_1}\right)=\frac{1}{2}\&times;\mathrm{erfc}\sqrt{({\mathrm{<figure-callout\; id="0"\; label="SNR"\; filenames="120604100349.png,120604100400.png"\; state="\{\{state\}\}">SNR</figure-callout>}}_0+10{\log }_{10}{(d/d_1)}^2)}---\left(8\right)$

${\mathrm{<figure-callout\; id="2"\; label="P\; e"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_e={\&Integral;}_{-\&infin;}^0\frac{1}{\sqrt{2\mathrm{\&pi;}}{\mathrm{\&sigma;}}_n}{e}^{-{(x-\mathrm{\&mu;})}^2/2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="120604100400.png"\; state="\{\{state\}\}">n</figure-callout>}}^2}=\frac{1}{2}\&times;\mathrm{erfc}\left(\sqrt{{\mathrm{SNR}}_2}\right)=\frac{1}{2}\&times;\mathrm{erfc}\sqrt{({\mathrm{<figure-callout\; id="0"\; label="SNR"\; filenames="120604100349.png,120604100400.png"\; state="\{\{state\}\}">SNR</figure-callout>}}_0+10{\log }_{10}{(d/({d-d}_1\left)\right)}^2)}---\left(9\right)$

Wherein, P _E1, P _E2And P _eBe respectively the bit error rate of transmitting terminal to the relaying star, the relaying star is to the bit error rate of receiving terminal, and transmitting terminal is to the bit error rate of receiving terminal point-to-point direct communication, SNR ₀, SNR ₁And SNR ₂Represent the bit signal to noise ratio of transmitting terminal to the relaying star respectively, the relaying star is to the bit signal to noise ratio of receiving terminal, and transmitting terminal is to the bit signal to noise ratio of receiving terminal point-to-point direct communication.

The present invention divides following two kinds of situation to T _Def2The time delay of section is carried out modeling analysis.

Case1：d ₁＜＝d ₂

Wherein, d ₁Be the distance of transmitting terminal to the relaying star, d ₂Be the distance of relaying star to receiving terminal, the RSF-CFDP part transmission course under the Case1 situation is as shown in Figure 2.Transmitting terminal can return earlier to the PDU of relaying star span line and finish, and this moment, the PDU re-transmission of this section did not influence the PDU re-transmission of relaying star to receiving terminal.

In the case, the propagation delay time of time-delay detection-phase II is following:

${\mathrm{<figure-callout\; id="2"\; label="T\; def"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{def}}=\frac{[E\left(M\right)-1](2{\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}+T_{\mathrm{NAK}})}{1-{\mathrm{<figure-callout\; id="2"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}+\frac{{\mathrm{NT}}_{\mathrm{PDU}}(\frac{1}{1-P_{\mathrm{ePDU}2}}-1)}{1-P_{\mathrm{eNAK}2}}---\left(10\right)$

Wherein: $E\left(M\right)=1+\underset{m-1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}[1-{(1-P_{\mathrm{EPDU}2}^m)}^N]$

Case 2:d ₁＞d ₂, opposite with situation 1, its transmission course is as shown in Figure 3.

In the case, transmission detection II is following with the propagation delay time sum that time-delay detects II:

${\mathrm{<figure-callout\; id="2"\; label="T\; inc"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{inc}}+{\mathrm{<figure-callout\; id="2"\; label="T\; def"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{def}}={\mathrm{<figure-callout\; id="1"\; label="T\; def"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{def}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}}{1-P_{\mathrm{eNAK}2}}---\left(11\right)$

$=\frac{[E\left(M\right)-1]({2\mathrm{<figure-callout\; id="1"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}+T_{\mathrm{NAK}})}{1-{\mathrm{<figure-callout\; id="1"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}+\frac{{\mathrm{NT}}_{\mathrm{PDU}}(\frac{1}{1-P_{\mathrm{ePDU}1}}-1)}{1-{\mathrm{<figure-callout\; id="1"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="T\; prop"\; filenames="120604100400.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{prop}}}{1+{\mathrm{<figure-callout\; id="2"\; label="P\; eNAK"\; filenames="120604100400.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{eNAK}}}$

Be example referring to Fig. 4 to Fig. 7 emulation with the communication task of mars exploration in the lump please; Analysis is adopted the delay performance of time-delay NACK type CFDP (RSF-CFDP) agreement that storage is transmitted based on relaying proposed by the invention at Mars-earth communication down link, and with other three kinds of traditional deep space FTP schemes: traditional point-to-point CFDP, relaying amplify to be transmitted CFDP (RAF-CFDP) and compares analysis with relaying decoding forwarding CFDP (RDF-CFDP) scheme.The agreement key parameter mainly comprises: bit error rate, Bit Transmission Rate, PDU quantity and length etc. the scheme Effect on Performance simultaneously.The result shows, at the deep space environment of high bit-error (like BER＞10 ^-4Condition) under, the time-delay NACK type CFDP agreement more traditional direct host-host protocol scheme of point-to-point, relaying amplification retransmission protocol scheme and the relaying decoding retransmission protocol scheme on the propagation delay time index that the present invention is based on relaying storage forwarding obtained tens to hundreds of a.u. gains.In order to reduce the time delay of deep space file transfer; Improve file transfer efficient; The present invention is based on the thought that shortens the point to point link distance, introduce the via node store-and-forward mechanism traditional time-delay NACK type CFDP protocol transmission mechanism is improved, reduce the error probability of data; Reduce the time delay that feedback retransmits, and then the file transfer efficient that improves.Above content is to combine concrete preferred implementation to the further explain that the present invention did, and can not assert that practical implementation of the present invention is confined to these explanations.For the those of ordinary skill of technical field under the present invention, under the prerequisite that does not break away from the present invention's design, can also make some simple deduction or replace, all should be regarded as belonging to protection scope of the present invention.

Claims (6)

1. method for transmitting deep space file based on relaying storage-forwarding; Be used for file is sent to receiving terminal by transmitting terminal through the relaying star; It is characterized in that: said method for transmitting deep space file based on relaying storage-forwarding comprises transmitting terminal to relaying star stage and relaying star to receiving terminal stage

Transmitting terminal to the relaying star stage further may further comprise the steps:

Step (a), transmitting terminal send comprise MPDU, EOF all PDU to the relaying star, send at transmitting terminal that the relaying star does not return any NAK or ACK information in the process of PDU, transmitting terminal sends out and gets into step (b) after all PDU and relaying star are received EOF;

Step (b), relaying star constantly return NAK information and have received that up to the relaying star relaying star returns FIN to transmitting terminal after all PDU of whole file, relaying star have received all PDU of whole file, and the relaying star finishes transmission course and also closes link;

Relaying star to the receiving terminal stage further may further comprise the steps:

Step (c), relaying star send all PDU to transmitting terminal; In step (c); After the EOF that relaying magnitude end to be sent sends arrives, send paid-in whole PDU to receiving terminal, promptly said step (c) starts from the moment that the step (a) of transmitting terminal to relaying star in the stage finishes;

Return NAK to the relaying star after the integrality of step (d), receiving terminal detection file, require the relaying star that the PDU of disappearance is retransmitted;

Step (e), relaying star are accepted the NAK that receiving terminal returns, and the retransmission list of the PDU of required re-transmission is checked and confirmed to the relaying star;

Step (f), the affirmation of relaying star need the PDU that retransmits whether to be retransmitted to the relaying star by transmitting terminal, and the relaying star will be sent to the relaying star by transmitting terminal and the PDU in the retransmission list of PDU is sent to receiving terminal; In this step; The relaying star will not waited for after all PDU that need transmitting terminal to retransmit all arrive and begin to retransmit again; Received and the PDU in retransmission list but retransmit immediately unreceived PDU waits for the NAK of next receiving terminal checks whether can retransmit when arriving again;

Step (g), repeating step (d) are received all PDU of file to (f) up to receiving terminal;

Step (h), receiving terminal return FIN to the relaying star, and the relaying star is received FIN and return ACK (FIN) to receiving terminal that receiving terminal is accepted ACK (FIN) and closed link, ends file transfer.

2. according to the said method for transmitting deep space file based on relaying storage-forwarding of claim 1, it is characterized in that: said transmitting terminal to relaying star adopts time-delay NACK type CFDP protocol transmission algorithm to carry out transfer of data in the stage.

3. according to the said method for transmitting deep space file of claim 2, it is characterized in that based on relaying storage-forwarding: said transmitting terminal to the distance of relaying star smaller or equal to the distance of relaying star to receiving terminal.

4. according to the said method for transmitting deep space file based on relaying storage-forwarding of claim 3, it is characterized in that: said method for transmitting deep space file based on relaying storage-forwarding satisfies following formula,

$T_{\mathrm{def}2}=\frac{[E\left(M\right)-1](2T_{\mathrm{prop}2}+T_{\mathrm{NAK}})}{1-P_{\mathrm{eNAK}2}}+\frac{{\mathrm{NT}}_{\mathrm{PDU}}(\frac{1}{1-P_{\mathrm{ePDU}2}}-1)}{1-P_{\mathrm{eNAK}2}}$

Wherein: $E\left(M\right)=1+\underset{m-1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}[1-{(1-P_{\mathrm{EPDU}2}^m)}^N]$

T _Def2For the relaying star in the file transfer of receiving terminal the relaying star in all PDU retransmission processes to the spatial transmission time delay sum of receiving terminal and the processing delay sum of giving out a contract for a project when retransmitting; T _Prop2Be the propagation delay of relaying star to receiving terminal; T _NAKThe time delay of giving out a contract for a project for NAK; P _ENAK2Be the packet loss of relaying star to receiving terminal section NAK; N is the number of PDU; T _PDUThe time delay of giving out a contract for a project for PDU; P _EPDU2Be the packet loss of relaying star to receiving terminal section PDU; P _ENAK2Be the packet loss of relaying star to receiving terminal section NAK; E (M) is the expectation of M, wherein being defined as of M: suppose K _iThe number of times of transmission altogether when being i PDU transmission success makes that M is the number of transmissions of the maximum PDU of number of retransmissions, and then M is max{K ₁, K ₂, K ₃...,, then M-1 is total number of retransmissions.

5. according to the said method for transmitting deep space file of claim 2, it is characterized in that based on relaying storage-forwarding: said transmitting terminal to the distance of relaying star greater than the distance of relaying star to receiving terminal.

6. according to the said method for transmitting deep space file based on relaying storage-forwarding of claim 5, it is characterized in that: said method for transmitting deep space file based on relaying storage-forwarding satisfies following formula,

$T_{\mathrm{inc}2}+T_{\mathrm{def}2}=T_{\mathrm{def}1}+\frac{T_{\mathrm{prop}2}}{1-P_{\mathrm{eNAK}2}}$

$=\frac{[E\left(M\right)-1]({2T}_{\mathrm{prop}1}+T_{\mathrm{NAK}})}{1-P_{\mathrm{eNAK}1}}+\frac{{\mathrm{NT}}_{\mathrm{PDU}}(\frac{1}{1-P_{\mathrm{ePDU}1}}-1)}{1-P_{\mathrm{eNAK}1}}+\frac{T_{\mathrm{prop}2}}{1+P_{\mathrm{eNAK}2}}$

Wherein: $E\left(M\right)=1+\underset{m-1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}[1-{(1-P_{\mathrm{EPDU}2}^m)}^N]$

T _Inc1Processing delay and transmitting terminal the spatial transmission time delay of giving out a contract for a project for all packets of transmitting terminal to the relaying star; T _Inc2For sending processing delay and relaying star the spatial transmission time delay of giving out a contract for a project of all packets that the relaying star receives at this moment to receiving terminal; T _Def2For the relaying star in the file transfer of receiving terminal the relaying star in all PDU retransmission processes to the spatial transmission time delay sum of receiving terminal and the processing delay sum of giving out a contract for a project when retransmitting; T _Prop1Be the propagation delay of transmitting terminal to the relaying star; T _NAKThe time delay of giving out a contract for a project for NAK; N is the number of PDU; T _PDUThe time delay of giving out a contract for a project for PDU; P _EPDU1Be the packet loss of transmitting terminal to relaying star section PDU; P _ENAK1Be the packet loss of transmitting terminal to relaying star section NAK; T _Prop2Be the propagation delay of relaying star to receiving terminal; P _ENAK2Be the packet loss of relaying star to receiving terminal section NAK; N is the number of PDU; E (M) is the expectation of M, wherein being defined as of M: suppose K _iThe number of times of transmission altogether when being i PDU transmission success makes that M is the number of transmissions of the maximum PDU of number of retransmissions, and then M is max{K ₁, K ₂, K ₃...,, then M-1 is total number of retransmissions.

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