CN104243097A - Data transmission method and system based on satellite network - Google Patents
Data transmission method and system based on satellite network Download PDFInfo
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Abstract
The invention provides a data transmission method and system based on a satellite network. The method includes the steps that data are transmitted in a UDP transmission mode, and a field is added on the basis of a UDP data header, wherein the field comprises a serial number representing a currently sent data package, serial numbers representing all data packages received by a receiving end, and the number of received data packages contained at the receiving end; in the processing of transmitting data in the UDP transmission mode, the receiving end sends the serial numbers of all the received data packages to a sending end after receiving the data packages transmitted by the sending end; the maximum number of the data packages in a channel is determined according to the serial number of the currently sent data package and the termination serial number, received by the receiving end, of the data package; when the maximum number of the data packages in the channel is smaller than the number of the received data package contained at the receiving end, the lost data packages are retransmitted. The data transmission method and system based on the satellite network solve the problem that the satellite network is low in transmission efficiency and not reliable in transmission under the high package loss rate.
Description
Technical field
The present invention relates to network transmission technology field, more specifically, relate to a kind of data transmission method based on satellite network and system.
Background technology
In geo-synchronous orbit satellite communication, satellite network Bandwidth-Delay product is large, and round-trip delay is large, thus causes Bandwidth-Delay product also larger.In addition, owing to there is no the protection of medium on satellite channel, under the impact of the factor such as electromagnetic interference, weather conditions, cause the error rate higher.When the widely used TCP of ground network (Transmission Control Protocol, transmission control protocol) is applied to satellite network, the throughput of network is subject to serious restriction.For above-mentioned large Bandwidth-Delay product or high bit error, researcher proposes the improvement version of a lot of TCP, as Westwood, Veno, BIC etc., these improvement applications are in satellite network, communication efficiency can be improved to a certain extent, but because these amendments will keep the compatibility of existing TCP version, its flexibility can be restricted to a certain extent.And by the restriction of the regulation of existing protocol, and the transfer of data of specific area can not be widely used in based on the application layer protocol of UDP (User Datagram Protocol, User Datagram Protocol).Wherein, UDP is a kind of connectionless transport layer protocol in OSI Reference Model, it is mainly used in the transmission not requiring order of packets to arrive, and the inspection of transmitted in packets order is completed by application layer with sequence, provides towards the simple of affairs but unreliable information transfer service.Udp protocol is the interface of IP agreement and upper-layer protocol substantially.
Transmission Control Protocol is SCCP connection-oriented, end to end transport layer protocol, it provides a kind of transmission means reliably.At high latency, when the Broadband Satellite of high packet loss uses TCP, along with the increase TCP of network delay decreases congestion window, but available bandwidth can not be recovered, the efficiency step-down thus of Transmission Control Protocol.In addition, the inequitable of TCP congestion control carries out RTT (Round-Trip Time, round-trip delay), and the concurrent TCP flow having different round-trip delay incites somebody to action share of bandwidth partially, also becomes serious problems.
The main cause of congested generation is that inadequate resource that network provides is to meet the demand of user, and these resources comprise the disposal ability of spatial cache, link bandwidth capacity and intermediate node.Design mechanism due to the Internet causes it to lack " call access control " ability, can cannot limited subscriber quantity when Internet resources are not enough, and can only continue as user's service by reducing service quality.
Udp protocol is connectionless agreement, has resource consumption little, the advantage that processing speed is fast, but the unreliability of udp protocol is very large, can not ensure the correctness of packet, not have affirmation mechanism, packet is unordered propagation in a network, the easy packet loss when network condition is bad.Udp protocol is just gone out the Packet Generation that application program passes to IP layer, does not ensure that packet can arrive destination, thus, in a network with UDP send data cannot determine data whether arrive or data whether correct.
Based on above feature, need a kind of fast and flexible, under high packet loss environment, support the method for the reliable transfer of data of high-performance.
Summary of the invention
In view of the above problems, the object of this invention is to provide a kind of data transmission method based on satellite network and system, by the transmission means of UDP and network real-time monitoring, packet is transmitted, to solve satellite network under high packet loss, the low and insecure problem of transmission of efficiency of transmission.
On the one hand, the invention provides a kind of data transmission method based on satellite network,
Adopt the transmission means transfer of data of UDP, the basis of UDP message header increases the sequence number comprising the packet representing current transmission, the sequence number representing all packets that receiving terminal receives, represent that receiving terminal holds the field of the quantity of the packet received; Wherein,
In the process of transmission means transmission data adopting UDP:
The sequence number of all packets received, after the packet receiving transmitting terminal transmission, is sent to transmitting terminal by receiving terminal, wherein,
The sequence number of all packets received comprises the termination sequence number of the packet received, and, each packet sets a time-out time by timer, according to the sequence number of all packets that time-out time and the described receiving terminal of packet setting receive, determines the packet lost;
The termination sequence number of the packet that transmitting terminal receives according to the sequence number of the packet of current transmission and receiving terminal, determines the maximum quantity of the packet be trapped in transmission channel; Wherein,
When the maximum quantity of the described packet be trapped in transmission channel be less than receiving terminal hold the quantity of the packet received time, the packet of described loss retransmits by transmitting terminal.
In addition, preferred scheme is, in the process of maximum quantity determining the packet be trapped in transmission channel, adopts following formula to obtain the maximum quantity of the packet be trapped in transmission channel:
P＝sndq-E
Wherein, P represents the maximum quantity of the packet be trapped in transmission channel;
Sndq represents the sequence number of the packet of current transmission;
E represents the termination sequence number of the packet that receiving terminal receives.
In addition, preferred scheme is, in the process of transmission data, is monitored in real time by the process of network monitoring to transmission data,
The network condition of process of transmission data is monitored in network monitoring in real time, when network monitoring identify current network conditions change time, amendment network parameter; Wherein,
Network parameter comprises network delay and transmission rate;
Network delay comprises transmission time-out, reconnects time-out, transmission times, number of retransmissions;
Transmission rate, goes out real-time network transmission speed by the information analysis of the packet transmitted.
In addition, preferred scheme is, is carrying out in the process of monitoring in real time by network monitoring to data transmission procedure,
Set up RTCP communication module at transmitting terminal and receiving terminal, network monitoring calculates current packet loss by the RTP bag received, and wherein, packet loss algorithm is as follows:
Loos_Pack(z)＝C_Loss/C_Expect
＝(C_Expect–C_Received)/C_Expect
＝1-(C_Received/C_Expect)
Wherein, Loos_Pack (z) represents current packet loss;
C_Loss represents the number of the packet lost in current time sheet;
C_Expect is the number of the packet that should receive in current time sheet;
C_Received is the number of the packet of the actual receipts of current time sheet.
In addition, preferred scheme is, the packet loss calculated according to current time sheet and the transmission rate of current time, obtain out the transmission rate of future time sheet by corresponding strategy, and adopt multiplicative to decline, additivity rises and carries out flow control algorithm, and algorithm is as follows:
Wherein, L (X+1) transmission rate that is future time sheet;
L (X) is current time sheet transmission rate;
The packet loss that C_loss (X) is current time sheet;
C_up cuts thresholding on being; C_down is incision threshold value.
On the other hand, the present invention also provides a kind of data transmission system based on satellite network, for adopting the transmission means transmission data of UDP, the basis of UDP message header increasing the sequence number comprising the packet representing current generation, the sequence number representing all packets that receiving terminal receives, represents that receiving terminal holds the field of the data packet number received;
Wherein, the data transmission system of satellite network, comprising:
Sequence number feedback unit, for after the packet receiving transmitting terminal transmission, all packet sequence numbers received are sent to transmitting terminal, and wherein, the sequence number of all packets received comprises the termination sequence number of the packet received;
The packet acquiring unit lost, for being set the time-out time of each packet by timer, according to the sequence number of all packets that time-out time and the receiving terminal of packet setting receive, determines the packet lost;
The number obtainment unit of the packet in channel, the termination sequence number of the packet that sequence number and receiving terminal for the packet according to current transmission receive, determines the maximum quantity of the packet be trapped in transmission channel;
Data packet retransmission unit, for be less than when the maximum quantity being trapped in the packet in transmission channel receiving terminal hold the quantity of the packet received time, the packet of loss retransmits by transmitting terminal.
From technical scheme above, data transmission method based on satellite network of the present invention and system, by the transmission means of UDP and network real-time monitoring, packet is transmitted, to solve satellite network under high packet loss, the low and insecure problem in transport part of efficiency of transmission.Transmission rate can be improved by the transmission means of UDP; By delay and the transmission rate of monitoring network, catch the real-time status of network, amendment network parameter, improves data transmission efficiency more efficiently.
In order to realize above-mentioned and relevant object, will describe in detail and the feature particularly pointed out in the claims after one or more aspect of the present invention comprises.Explanation below and accompanying drawing describe some illustrative aspects of the present invention in detail.But what these aspects indicated is only some modes that can use in the various modes of principle of the present invention.In addition, the present invention is intended to comprise all these aspects and their equivalent.
Accompanying drawing explanation
By reference to the content below in conjunction with the description of the drawings and claims, and understand more comprehensively along with to of the present invention, other object of the present invention and result will be understood and easy to understand more.In the accompanying drawings:
Fig. 1 is the data transmission method flow chart based on satellite network according to the embodiment of the present invention;
Fig. 2 is the data message structural representation according to the embodiment of the present invention;
Fig. 3 is the data transmission system logic diagram based on satellite network according to the embodiment of the present invention.
Label identical in all of the figs indicates similar or corresponding feature or function.
Embodiment
In the following description, for purposes of illustration, in order to provide the complete understanding to one or more embodiment, many details have been set forth.But, clearly, also these embodiments can be realized when there is no these details.
Mentioning network satellite in aforementioned adopts Transmission Control Protocol to carry out transfer of data, the efficiency step-down of Transmission Control Protocol.In addition, inequitable RTT (Round-Trip Time, round-trip delay) of TCP congestion control also becomes serious problems.And udp protocol is connectionless agreement, unreliability is very large, and can not ensure the correctness of packet, and also do not have affirmation mechanism, packet is unordered propagation in a network, the easy packet loss when network condition is bad simultaneously.The present invention is directed to udp protocol Problems existing, adopt increase on the basis of UDP message header flag bit, sequence number, confirmation number, window size the transfer of data header of field carry out transfer of data, and in transmitting procedure, network monitoring is carried out to it, according to the real-time condition of monitoring, time update network parameter, makes the carrying out of packet high efficient and reliable transmit.
Below with reference to accompanying drawing, specific embodiments of the invention are described in detail.
In order to the transmission method under satellite network high packet loss environment provided by the invention is described, Fig. 1 shows the data transmission method flow process based on satellite network according to the embodiment of the present invention.
As shown in Figure 1, data transmission method based on satellite network provided by the invention, adopt the transmission means transmission data of UDP, the basis of UDP message header increases the sequence number comprising the packet representing current transmission, the sequence number representing all packets that receiving terminal receives, represent that receiving terminal holds the field of the quantity of the packet received.
That is, adopting the transmission means of UDP to carry out in transmitting procedure to packet, data packet transmission layer adopts the transmission means based on UDP, data transfer layer header be UDP message header basis on increase flag bit, sequence number, confirmation number and window size.
Wherein, flag bit: play the effect distinguished and control bag and application data.
Sequence number: play the effect of mark bag uniquely identified, realize the sequence to packet, to ensure the correctly complete of packet.
Confirmation number: if represent that current bag is ACK bag, so confirmation expression is the sequence number which promises wrap, after being mainly used to confirm to send application data bag, whether receiving terminal receives, also be just say, for receiving terminal is after receiving correctly complete packet, all packet sequence numbers received are returned to transmitting terminal.
Window size: be used for transmitting adjustment sliding window size, regulate sliding window to adapt to network environment; Represent that receiving terminal can hold the quantity of the packet received.
It should be noted that, data transfer layer is based on the transmission means of UDP, and UDP master data header is made up of 4 fields, and wherein each field takies 2 bytes (16).Concrete field is followed successively by: source port number, destination port number, datagram length, check value.
Wherein, data transfer layer header increases by 4 fields on UDP message header basis, and concrete field is followed successively by: flag bit, sequence number, confirmation number, window size.Adopt specified number according to message structure to illustrate in the present invention, Fig. 2 shows the data message structure according to the embodiment of the present invention.As shown in Figure 2, the concrete field of data message structure that the present invention adopts is followed successively by: source port number, destination port number, datagram length, check value, flag bit, sequence number, confirmation number and window size.
Flag bit: take 1,0 is represented as application data bag, and 1 representative confirms to control bag.
Sequence number: take 4 bytes, the sequence number of each non-retransmission packet increases progressively to add 1, covers when sequence number arrives 2^31-1 time; Its object can sort when arriving destination in order to packet, and knows whether packet is lost, and guarantees the correctly complete of data.
Confirmation number: take 4 bytes, be the packet sequence number+1 needing to confirm, its object, in order to receiving terminal is after receiving correctly complete packet, returns to promising of transmitting terminal.
Window size: take 2 bytes, represents the quantity of the packet that receiving terminal can receive.
Wherein, the process of the transmission means of UDP transmission data is being adopted specifically to comprise:
S110: the sequence number of all packets received, after the packet receiving transmitting terminal transmission, is sent to transmitting terminal by receiving terminal.
Wherein, the sequence number of all packets received comprises the termination sequence number of the packet received, and each packet sets a time-out time by timer, according to the sequence number of all packets that time-out time and the receiving terminal of packet setting receive, determine the packet lost.
That is, the sequence number of all packets received is sent to transmitting terminal by receiving terminal, and transmitting terminal can receive the ACK bag containing negative sense feedback information data.Wherein, SNACK (Selective Negative Acknowledgment) is negative sense feedback information data.Negative sense feedback information data comprises start sequence number and the packet loss gap of the packet that the packet information, the receiving terminal that correctly do not receive receive; Packet loss gap NAK represents, NAK represents the loss of individual data bag by a sequence number or represents a packet loss section by initial, termination sequence number.
It should be noted that, the packet loss caused by network congestion in satellite communication environment is all generally continuous appearance, and the data-bag lost caused by error code distributes more even in communication; So according to this feature, the present invention adopts SNACK (Selective Negative Acknowledgment) negative sense feedback information data to carry out Fast retransmission.(two-part information is comprised containing the packet information correctly do not received in SNACK bag, the information of the packet namely lost and be trapped in the information of the packet in transmission channel), (receiving terminal not only receives only the start sequence number of packet and stops sequence number the start-stop sequence number START of all buffer memory bags of receiving terminal and END, comprise the sequence number receiving all packets), and packet loss gap.
In the present invention, transmitting terminal arranges a timer and is used for checking all packets, each packet arranges a fixing time-out time, when the packet sent exceedes the time of setting, receiving terminal does not receive, so just can think and become the packet of loss by this data-bag lost, need to retransmit.
Need illustrate but, timer is the instrument of function activation period sexual behavior part, the meaning is exactly when timer is after each packet sets a fixed-timeouts time, timer can trigger alarm event as alarm clock after the time, because timer sets a time to each packet, corresponding event can be triggered when timer arrives the corresponding time, event is exactly that the packet received in the time to timer setting is analyzed, timer can check that the data which sends are surrounded by the sequence number not receiving correspondence, and the time-out time sending the transmitting time of wrapping and compare transmission bag is subtracted by current time, if be greater than time-out time, be defined as overtime packet loss.
S120: the termination sequence number of the packet that transmitting terminal receives according to the sequence number of the packet of current transmission and receiving terminal, determines the maximum quantity of the packet be trapped in transmission channel.
Particularly, in the process of maximum quantity obtaining the packet be trapped in transmission channel, following formula is adopted to obtain the maximum quantity of the packet be trapped in transmission channel:
P＝sndq-E
Wherein, P represents the maximum quantity of the packet be trapped in transmission channel; Sndq represents the sequence number of the packet of current transmission; E represents the termination sequence number of the packet that receiving terminal receives.
That is, when transmitting terminal receives the ACK bag comprising SNACK time, to the packet occurred in all NAK, in transmission buffer memory, increase it lose number of times, record the sequence number sndq of the packet of current transmission, calculate the largest possible number thereof p=sndq-E of the packet be detained in the channel.Further, the value of p increases by 1 after transmission packet, reduces 1 after receiving ACK.It should be noted that, have in the buffer memory of transmitting terminal and the specific algorithm of packet is received, records and processed.
S130: when the maximum quantity being detained packet be in the transmission signal less than receiving terminal hold the quantity of the packet received time, the packet of loss retransmits by transmitting terminal.
That is, when the quantity of being detained packet is in the transmission signal less than window size, the packet of loss retransmits by transmitting terminal, and wherein, window size is the quantity that the receiving terminal that the basis of datagram header in the transmission means of UDP increases holds the packet received.
Window size also can be shown: the data packet number that can send at most in the RTT time.RTT (Round-Trip Time, round-trip delay).It is important performance index in a computer network, represents from transmitting terminal sends data, receives the confirmation (receiving terminal just sends confirmation after receiving data immediately) from receiving terminal, the time delay altogether experienced to transmitting terminal.
It should be noted that, when p<wd (window size), transmitting terminal can send packet, the packet sent can be lose number of times to reach 3 times and the packet not yet retransmitted, also the new packet be in wd can be sent, send window can be advanced continuously, by determining the packet of loss thus reducing transmitting terminal because the blindness of transmitting terminal when retransmitting, to improve packet loss retransmission efficiency.
It should be noted that, in the process that packet is retransmitted, monitored in real time by the process of network monitoring to transfer of data.
In an embodiment of the present invention, adopt UDP transmission means transmission packet in, the network condition in transmitting procedure is monitored in network monitoring in real time, when monitoring program identify current network conditions change time, amendment network parameter; Wherein, network parameter comprises two classes: a class is network delay, specifically comprises transmission time-out, reconnects time-out, transmission times, number of retransmissions; Another kind of is transmission rate, by the information of packet transmitted, analyzes real-time network transmission speed.
That is, amendment network parameter is the last layer at Fast retransmission, has one to monitor network condition in responsible monitoring transmitting procedure.When monitor identify current network conditions change time, amendment network parameter; When monitoring, passing threshold and recognizer control.
The parameter of network delay be all agreement itself intrinsic, by the adjustment of these parameters, agreement value is inherently changed along with the change of network, makes it to have more practical significance.It is that let us converses according to transmission rate knowledge the size that we send buffering area when sending content that transmission rate monitors the effect played, and utilizes network more efficiently.
Wherein, it should be noted that, the upper strata of transfer of data utilizes network monitoring to on-the-fly modify network parameter: by delay and the transmission rate of monitoring network, catch the real-time status of network.When the situation of suspension occurs, can the carrying out of blocked task, until network is unimpeded; Its objective is to improve data transmission efficiency when network packet loss rate is high.
Monitor in the process of the network condition of the process of transmission data in real time in network monitoring, packet loss is that network real-time status shows the most intuitively, RTCP (Real-time Transport Control Protocol is set up in transmission two ends (transmitting terminal and receiving terminal), RTCP Real-time Transport Control Protocol) communication module, network monitoring calculates current packet loss by RTP (RTP) bag received, wherein, packet loss algorithm is as follows:
Loos_Pack(z)＝C_Loss/C_Expect
＝(C_Expect–C_Received)/C_Expect
＝1-(C_Received/C_Expect)
Wherein, Loos_Pack (z) represents current packet loss; C_Loss represents the number of the packet lost in current time sheet; C_Expect is the number of the packet that should receive in current time sheet; C_Received is the number of the packet of the actual receipts of current time sheet.
Wherein, monitor in the process of the network condition of the process of transmission data in real time in network monitoring, control strategy main purpose is responsible for the strategy providing flow control, the packet loss calculated according to current time sheet and the transmission rate of current time, the transmission rate of future time sheet is obtained out by corresponding policy calculation prediction, employing multiplicative declines, and additivity rises and carries out flow control algorithm, and algorithm is as follows:
Wherein, L (X+1) transmission rate that is future time sheet; L (X) is current time sheet transmission rate; The packet loss that C_loss (X) is current time sheet; C_up cuts thresholding on being; C_down is incision threshold value.
It should be noted that, C_loss packet loss is sent in policy control and judges, cuts thresholding C_up (C_up=0 on packet loss is not more than, represent there is no packet loss), then traffic Promotion Strategy, lifting K per second (K=10Kbps, regular length slowly increases); If packet loss C_loss is greater than incision threshold value C_down (C_down=5%), then performs and reduce traffic policy, be multiplied by the deceleration parameter of a >1.If packet loss is larger, effect is that 1-C_Loss will be less, and target bit rate decrease speed is faster, so more can effectively avoid congested appearance, the utilization rate of higher raising bandwidth high packet loss Time Bandwidth.It should be noted that, monitoring in network monitoring in the process of the network condition of the process of transmission data in real time, by controlling message, the transmission delay that Real-time Obtaining is current.Simultaneously can decision network whether unobstructed, the foundation of process is provided to other modules.Further, the information of transmitted data amount provided by other modules, analyzes real-time network transmission speed.
In the process of carrying out network control, by the delay of network and the analysis of transmission rate, judge suspension, network recovery, network state changes and network state keeps four kinds of network states.The control of network parameter is comprised to buffering area, connects time-out time, reconnects number of times, reconnects interval etc.
Wherein, network recovery: when network recovers from suspension is abnormal, the acquisition of network control module meeting open network parameter, makes Internet Transmission proceed.
Network state changes: when network condition changes, postpone or threshold value that the change of speed is variable more than one time, network control module can revise the parameter of network, and Internet Transmission is carried out with the fastest speed.
In the present invention, network state is obtained by network validation core algorithm; Its detailed process comprises: first, records N network state, the mean value/median of computing network state; Then, current average/median is compared with history average/median, if ratio exceedes threshold value (ratio < threshold value <1 or 1< threshold value < ratio), then think that network state changes, otherwise (threshold value < ratio <1 or 1< ratio < threshold value) then thinks that network state does not change.
In order to udp protocol under further illustrating satellite network communication environment is relative to the laser propagation effect of Transmission Control Protocol, compare for the laser propagation effect of the IFEP agreement developed based on udp protocol and Transmission Control Protocol below.In laboratory environment, three groups of simulated experiment data of carrying out respectively prove, in following analogue test, and analog satellite network respectively, and apply IFEP agreement and Transmission Control Protocol transmission data.
First group is in speed limit upstream bandwidth 200KB/s, downlink bandwidth 200KB/s situation, and send 25MB data, test result is as follows:
The speed that IFEP agreement sends data is 26KB/S, the used time: 923s;
The speed that Transmission Control Protocol sends data is 24KS/S, the used time: 1028s.
Second group is in speed limit upstream bandwidth 2000KB/s, downlink bandwidth 2000KB/s situation, and send 412MB data, test result is as follows:
The speed that IFEP agreement sends data is 255KB/s, the used time: 1582s;
The speed that Transmission Control Protocol sends data is 242KB/s, the used time: 1664s.
3rd group is without speed limit in situation, and send 412MB data, test result is as follows:
The speed that IFEP agreement sends data is 4.7MB/s, the used time: 83s;
The speed that Transmission Control Protocol sends data is 3.6MB/s, the used time: 107s.
By test, IFEP agreement is better than Transmission Control Protocol under satellite network communication environment, this agreement compares Transmission Control Protocol under satellite communication environment significantly can promote file transmission efficiency, makes full use of the network bandwidth of effective use under high packet loss environment, ensures the complete, reliable of data.Therefore, in the present invention, make use of the characteristic that udp protocol is applicable to existing satellite network communication environment more, simultaneously in order to evade udp protocol Problems existing, add and control content and related algorithm, simultaneously with the addition of network monitoring and queue management content on udp protocol upper strata, and then solve unordered, the packet loss existed current satellite network communication process, the problem such as congested from different aspects and dimension.
Corresponding with said method, the present invention also provides a kind of data transmission system based on satellite network, and Fig. 3 shows the data transmission system logical construction based on satellite network according to the embodiment of the present invention.
As shown in Figure 3, the data transmission system 300 based on satellite network provided by the invention comprises: the maximum quantity acquiring unit 330 of the packet in sequence number feedback unit 310, the packet acquiring unit 320 lost, channel and the data packet retransmission unit 340 of loss.
Data transmission system 300 based on satellite network transmits data for adopting the transmission means of UDP, the basis of UDP message header increases the sequence number comprising the packet representing current transmission, the sequence number representing all packets that receiving terminal receives, represents that receiving terminal holds the field of the data packet number received.
Wherein, sequence number feedback unit 310 is for after the packet receiving transmitting terminal transmission, and all packet sequence numbers received are sent to transmitting terminal, and wherein, the sequence number of all packets received comprises the termination sequence number of the packet received.
The packet acquiring unit 320 lost, for being set the time-out time of each packet by timer, according to the sequence number of all packets that time-out time and the receiving terminal of packet setting receive, determines the packet lost.
The termination sequence number of the packet that the maximum quantity acquiring unit 330 of the packet in channel receives for sequence number and the receiving terminal of the packet according to current transmission, determines the maximum quantity of the packet be trapped in transmission channel.
When the data packet retransmission unit 340 lost holds the quantity of the packet received for being less than receiving terminal when the maximum quantity being trapped in the packet in transmission channel, the packet of loss retransmits by transmitting terminal.
Data transmission system 300 based on satellite network also comprises network monitoring unit, and network monitoring unit is used for monitoring in real time data transmission procedure.
The number obtainment unit 330 of the packet in channel, in the process of maximum quantity obtaining the packet be trapped in transmission channel, adopts following formula to obtain the maximum quantity of the packet be trapped in transmission channel:
P＝sndq-E
Wherein, P represents the maximum quantity of the packet be trapped in transmission channel; Sndq represents the sequence number of the packet of current transmission; E represents the termination sequence number of the packet that receiving terminal receives.
Wherein, when network monitoring unit identify current network conditions change time, amendment network parameter; Wherein, network parameter comprises network delay and transmission rate: network delay comprises transmission time-out, reconnects time-out, transmission times, number of retransmissions; Transmission rate, goes out real-time network transmission speed by the information analysis of the packet transmitted.
Network monitoring unit is in the process of the network condition of the process of the data of monitoring transmission in real time, RTCP communication module is set up at transmitting terminal and receiving terminal, network monitoring unit calculates current packet loss by the RTP bag received, and wherein, packet loss algorithm is as follows:
Loos_Pack(z)＝C_Loss/C_Expect
＝(C_Expect–C_Received)/C_Expect
＝1-(C_Received/C_Expect)
Wherein, Loos_Pack (z) represents current packet loss; C_Loss represents the number of lost data packets in current time sheet; C_Expect is the number of the packet that should receive in current time sheet; C_Received is the number of the packet of the actual receipts of current time sheet.
Wherein, the transmission rate of the packet loss that network monitoring unit calculates according to current time sheet and current time, obtains out the transmission rate of future time sheet by corresponding strategy, and adopt multiplicative to decline, additivity rises and carries out flow control algorithm, and algorithm is as follows:
Wherein, L (X+1) transmission rate that is future time sheet;
L (X) is current time sheet transmission rate;
The packet loss that C_loss (X) is current time sheet;
C_up cuts thresholding on being; C_down is incision threshold value.
Wherein, it should be noted that, C_loss packet loss is sent in policy control and judges, thresholding C_up (C_up=0 is cut on packet loss is not more than, represent there is no packet loss), then traffic Promotion Strategy, lifting K per second (K=10Kbps, regular length slowly increases); If packet loss C_loss is greater than incision threshold value C_down (C_down=5%), then performs and reduce traffic policy, be multiplied by the deceleration parameter of a >1.If packet loss is larger, effect is that 1-C_Loss will be less, and target bit rate decrease speed is faster, so more can effectively avoid congested appearance, the utilization rate of higher raising bandwidth high packet loss Time Bandwidth.
Can be found out by above-mentioned execution mode, satellite network packet loss transmission method of the present invention and system, adopt increase on the basis of UDP message header flag bit, sequence number, confirmation number, window size the transfer of data header of field carry out transfer of data, and in transmitting procedure, network monitoring is carried out to it, according to the performance of monitoring, to network parameter time update, make satellite network at minimizing packet loss, maintenance efficiency of transmission does not change transmission that also can be reliable and stable.
The satellite network packet loss transmission method and system that propose according to the present invention is described in an illustrative manner above with reference to accompanying drawing.But, it will be appreciated by those skilled in the art that satellite network packet loss transmission method and system that the invention described above is proposed, various improvement can also be made on the basis not departing from content of the present invention.Therefore, protection scope of the present invention should be determined by the content of appending claims.
Claims (10)
1. the data transmission method based on satellite network, adopt the transmission means transmission data of UDP, the basis of UDP message header increases the sequence number comprising the packet representing current transmission, the sequence number representing all packets that receiving terminal receives, represent that receiving terminal holds the field of the quantity of the packet received; Wherein,
In the process of transmission means transmission data adopting UDP:
The sequence number of all packets received, after the packet receiving transmitting terminal transmission, is sent to transmitting terminal by receiving terminal, wherein,
The sequence number of all packets received comprises the termination sequence number of the packet received, and, each packet sets a time-out time by timer, according to the sequence number of all packets that time-out time and the described receiving terminal of packet setting receive, determines the packet lost;
The termination sequence number of the packet that transmitting terminal receives according to the sequence number of the packet of current transmission and receiving terminal, determines the maximum quantity of the packet be trapped in transmission channel; Wherein,
When the maximum quantity of the described packet be trapped in transmission channel be less than receiving terminal hold the quantity of the packet received time, the packet of described loss retransmits by transmitting terminal.
2., as claimed in claim 1 based on the transfer of data of satellite network, wherein, in the process of maximum quantity determining the packet be trapped in transmission channel, adopt following formula to obtain the maximum quantity of the packet be trapped in transmission channel:
P＝sndq-E
Wherein, P represents the maximum quantity of the packet be trapped in transmission channel;
Sndq represents the sequence number of the packet of current transmission;
E represents the termination sequence number of the packet that receiving terminal receives.
3., as claimed in claim 1 based on the data transmission method of satellite network, wherein, in the process of transmission data, monitored in real time by the process of network monitoring to transmission data,
The network condition in transmitting procedure is monitored in described network monitoring in real time, when described network monitoring identify current network conditions change time, amendment network parameter; Wherein,
Described network parameter comprises network delay and transmission rate;
Described network delay comprises transmission time-out, reconnects time-out, transmission times, number of retransmissions;
Described transmission rate, goes out real-time network transmission speed by the information analysis of the packet transmitted.
4. as claimed in claim 3 based on the data transmission method of satellite network, wherein, undertaken in the process of monitoring in real time by the process of network monitoring to transmission data,
Set up RTCP communication module at described transmitting terminal and described receiving terminal, described network monitoring calculates current packet loss by the RTP bag received, and wherein, packet loss algorithm is as follows:
Loos_Pack(z)＝C_Loss/C_Expect
＝(C_Expect–C_Received)/C_Expect
＝1-(C_Received/C_Expect)
Wherein, Loos_Pack (z) represents current packet loss;
C_Loss represents the number of the packet lost in current time sheet;
C_Expect is the number of the packet that should receive in current time sheet;
C_Received is the number of the packet of the actual receipts of current time sheet.
5. as claimed in claim 4 based on the data transmission method of satellite network, wherein,
The packet loss calculated according to current time sheet and the transmission rate of current time, obtain out the transmission rate of future time sheet by corresponding strategy, adopt multiplicative to decline, additivity rises and carries out flow control algorithm, and algorithm is as follows:
Wherein, L (X+1) transmission rate that is future time sheet;
L (X) is current time sheet transmission rate;
The packet loss that C_loss (X) is current time sheet;
C_up cuts thresholding on being; C_down is incision threshold value.
6. the data transmission system based on satellite network, for adopting the transmission means of UDP to carry out transfer of data, the basis of UDP message header increasing the sequence number comprising the packet representing current generation, the sequence number representing all packets that receiving terminal receives, represents that receiving terminal holds the field of the data packet number received;
Wherein, the data transmission system of satellite network, comprising:
Sequence number feedback unit, for after the packet receiving transmitting terminal transmission, all packet sequence numbers received are sent to transmitting terminal, and wherein, the sequence number of all packets received comprises the termination sequence number of the packet received;
The packet acquiring unit lost, for being set the time-out time of each packet by timer, according to the sequence number of all packets that time-out time and the described receiving terminal of packet setting receive, determines the packet lost;
The number obtainment unit of the packet in channel, the termination sequence number of the packet that sequence number and receiving terminal for the packet according to current transmission receive, determines the maximum quantity of the packet be trapped in transmission channel;
Data packet retransmission unit, for when described in the maximum quantity of packet that is trapped in transmission channel be less than receiving terminal hold the quantity of the packet received time, the packet of described loss retransmits by transmitting terminal.
7. defend the data transmission system based on satellite network as claimed in claim 6, wherein, the number obtainment unit of the packet in described channel, in the process of maximum quantity obtaining the packet be trapped in transmission channel, adopts following formula to obtain the maximum quantity of the packet be trapped in transmission channel:
P＝sndq-E
Wherein, P represents the maximum quantity of the packet be trapped in transmission channel;
Sndq represents the sequence number of the packet of current transmission;
E represents the termination sequence number of the packet that receiving terminal receives.
8., as claimed in claim 6 based on the data transmission system of satellite network, also comprise:
Network monitoring unit, for monitoring the network condition of transmission data procedures in real time; When described network monitoring unit identify current network conditions change time, amendment network parameter; Wherein,
When described network monitoring unit identify current network conditions change time, amendment network parameter;
Wherein,
Described network parameter comprises network delay and transmission rate:
Described network delay comprises transmission time-out, reconnects time-out, transmission times, number of retransmissions;
Described transmission rate, goes out real-time network transmission speed by the information analysis of the packet transmitted.
9. as claimed in claim 8 based on the data transmission system of satellite network, wherein, described network monitoring unit is carrying out in the process of monitoring in real time to the process of transmission data,
Set up RTCP communication module at described transmitting terminal and described receiving terminal, described network monitoring unit calculates current packet loss by the RTP bag received, and wherein, packet loss algorithm is as follows:
Loos_Pack(z)＝C_Loss/C_Expect
＝(C_Expect–C_Received)/C_Expect
＝1-(C_Received/C_Expect)
Wherein, Loos_Pack (z) represents current packet loss;
C_Loss represents the number of lost data packets in current time sheet;
C_Expect is the number of the packet that should receive in current time sheet;
C_Received is the number of the packet of the actual receipts of current time sheet.
10. as claimed in claim 9 based on the data transmission system of satellite network, wherein,
The transmission rate of the packet loss that described network monitoring unit calculates according to current time sheet and current time, obtains out the transmission rate of future time sheet by corresponding strategy, adopt multiplicative to decline, additivity rises and carries out flow control algorithm, and algorithm is as follows:
Wherein, L (X+1) transmission rate that is future time sheet;
L (X) is current time sheet transmission rate;
The packet loss that C_loss (X) is current time sheet;
C_up cuts thresholding on being; C_down is incision threshold value.
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| CN110278058A (en) * | 2019-06-05 | 2019-09-24 | 华为技术有限公司 | A kind of redundancy feedback method and communication device |
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| CN112114294A (en) * | 2020-09-24 | 2020-12-22 | 北京无线电测量研究所 | Control method and system of radar target simulator |
| CN112672223A (en) * | 2020-12-31 | 2021-04-16 | 北京中联合超高清协同技术中心有限公司 | High-reliability distribution method for ultra-high definition video satellite transmission |
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| CN112911638A (en) * | 2021-02-20 | 2021-06-04 | 上海吉盛网络技术有限公司 | Reliable communication method for optimizing wireless network load congestion by using UDP (user Datagram protocol) |
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