CN108769000A - A kind of highly efficient stream media transmission method for deep space environment - Google Patents
A kind of highly efficient stream media transmission method for deep space environment Download PDFInfo
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- CN108769000A CN108769000A CN201810507936.1A CN201810507936A CN108769000A CN 108769000 A CN108769000 A CN 108769000A CN 201810507936 A CN201810507936 A CN 201810507936A CN 108769000 A CN108769000 A CN 108769000A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/60—Network streaming of media packets
- H04L65/75—Media network packet handling
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/60—Network streaming of media packets
- H04L65/65—Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L67/00—Network arrangements or protocols for supporting network services or applications
- H04L67/50—Network services
- H04L67/56—Provisioning of proxy services
- H04L67/568—Storing data temporarily at an intermediate stage, e.g. caching
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
- H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
Abstract
Correcting and eleting codes are used for the transport layer of line service agreement BSS transmission plans by a kind of highly efficient stream media transmission method for deep space environment so that when an end node transmits streaming media resource via deep space network, have the energy of local recovery to the data packet of loss；Meanwhile by designing caching mechanism in receiving terminal, the redesign of packet structure solves out of order data, below the highly efficient stream media transmitting step of deep space environment：The first step transmission start stage；Second step transmission data；Including transmission data and receiving two processes of data.Correcting and eleting codes are applied in the transport layer of line service agreement BSS transmission plans by the present invention, when so that an end node transmitting the streaming media resources such as video via deep space network, increase the ability of local recovery, it is retransmitted to reduce, the efficiency of transmission being lifted under deep space communication network, the delivery time is reduced, while also optimizing the performance of real-time streaming service, improves the quality of real-time Transmission.
Description
Technical field
The present invention relates to a kind of network communication method, it is related to higher compared with long spacing distance, channel bit error rate for having
Efficient Stream Data Transmission under deep space communication environment is a kind of highly efficient stream media transmission method for deep space.
Background technology
Line service agreement (Bundle Streaming Service, BSS) transmission plan is in delay-tolerant network
On the basis of (Delay/Disruptive Tolerant Network, DTN) protocol stack, by beam protocol layer and transport layer
Between realize forwarding mechanism for the streaming media service of Information Network.Its design philosophy is to protect as far as possible
Hinder accessible Stream Data Transmission, so BSS transmission plans realize two kinds of services：" best-effort " service and
" reliable " is serviced.It can preferentially use " best-effort " to service this insecure mode the packet of arrival to pass in advance
It is defeated, because " best-effort " service need not establish connection, reduce the consumption of redundancy link foundation, to ensure real-time；
Packet or wrong packet for loss reuse " reliable " service and are retransmitted to ensure reliability.However in deep space environment
Channel particularity makes satellite communication process there are link delays big, and the high feature of packet loss, the resource overhead of re-transmission is big, and
BSS lacks corresponding mechanism for correcting errors.On the other hand, BSS takes out of order data and is directly placed into data to ensure real-time
The way in library, and be not transferred in the real-time display program of application layer, it is higher in packet loss, it can play in real time
Data can greatly reduce.Therefore a kind of novel flow-medium transmission method is developed for deep space communication network, realized in satellite chain
It efficiently, is reliably transmitted in road, is to build a deep space communication system important content needed to be considered.
In order to enable realizing the streaming media of high efficient and reliable in the following deep space communication network, mainly use will entangle the present invention
Code is deleted applied in BSS, by increasing redundancy appropriate in the transmission so that receiving terminal can local recovery go out the number of loss
According to reduction retransmits, to promote streaming media efficiency；Simultaneously by redesigning packet structure and design caching machine
System so that out of order data packet in a certain range can also be reordered and recover, and ensure the order of data,
Enable the real-time broadcasting smoothness of receiving terminal without interim card.
Invention content
It is an object of the invention to provide a kind of highly efficient stream media transmission method for deep space communication network, due to space
Information network is there is the particularity of high packet loss, long time delay, and the invention is for the efficiently transport stream matchmaker under deep space communication network
Body resource mitigates the negative effects such as the delivery time that deep space transmission condition particularity is brought is long, packet loss is high, easily interrupts.
Meanwhile taking the way of discarding different out of order data from other Streaming transfer protocols, the invention is for so that a certain range
Interior out of order data can also resequence and play in real time.
It can also resequence the invention enables a certain range of out of order data and play in real time.It solves the problems, such as
In comparing original BSS transmission plans, shorten the files in stream media delivery time, and increase the quality of real-time Transmission, promoted
User experience.In deep space communication network, since communication distance is remote, bad channel quality, long delay often interrupts, high bit-error
Channel characteristic bring huge challenge to the high efficiency of transmission of stream medium data.Therefore a kind of height suitable for deep space environment is proposed
Imitate flow-medium transmission method.
Technical scheme of the present invention：A kind of highly efficient stream media transmission method for deep space environment, one kind being used for deep space ring
Correcting and eleting codes are used for the transport layer of line service agreement BSS transmission plans so that an end segment by the highly efficient stream media transmission method in border
When point transmits streaming media resource via deep space network, there is the energy of local recovery to the data packet of loss；Meanwhile by receiving
End design caching mechanism, the redesign of packet structure solve out of order data, wherein specific steps：
Correcting and eleting codes are added in " best-effort " service layer of BSS, by the data for increasing redundancy so that receiving terminal has
There is certain error correcting capability, " best-effort " service layer of the transport layer of BSS transmission plans is added in correcting and eleting codes, relative to chain
The bottoms such as road floor coding has stronger error correcting capability；
Pass through the redesign to packet structure so that include sequence in the data message of " best-effort " service
Information；Pass through design caching mechanism so that the data of the same data block (Block) being ranked sequentially according to transmission,
And cache, it is decoded after collecting enough data so that the out of order data of the same data block can be played back orderly；
Coding, which is added, in transport layer can restore the data packet (transport layer message Segment) of length bigger, have stronger
Error correcting capability.
Correcting and eleting codes (erasure code) are added on the level of the transport layer；Wherein, the agreement that transport layer uses has：UDP,TCP,
Tetra- kinds of " green " LTP, " red " LTP agreements；Wherein UDP, " green " LTP are serviced for " best-effort "；TCP and
" red " LTP is serviced for " reliable ", and the agreement that suitable transport layer uses is selected according to actual application scenarios.
Correcting and eleting codes are added in " reliable " service, " reliable " of transport layer protocol is serviced, because retransmitting
Data be all by " reliable " service；
The highly efficient stream media transmitting step of deep space environment includes following：
The first step：The transmission start stage；It is connected firstly the need of establishing, when client is connect with server, due to BSS meetings
It is transmitted using to " reliable " service to ensure reliability；If using Transmission Control Protocol under " reliable " service,
It then needs to shake hands for 3 times, if using " red " ltp agreements under " reliable " service, need not shake hands, but by sending
End sends the data packet of an initialization connection, and then receiving terminal can postback one after several data segments (segment) and answer
It answers frame (ACK) and informs the case where transmitting terminal receives；In addition, the background process of a database can be opened in receiving terminal, and confirm
Database can be opened；This process can by all data received, either in real time, or retransmit, according to packet
Generated time is orderly to be stored in inside database, so that playback in future needs；
Second step：Transmission data；Including transmission data and receiving two processes of data：
3) transmission data process.
Step a：When transmitting terminal is received when upper level applications initiate new streaming medium content and receive request, transmitting terminal meeting
The beam that the stream medium data transmitted will be needed to be written to beam protocol layer (bundle protocol layer) sequentially in time
(bundle) in；Each beam can also record the generated time of beam；
Step b：Next beam to be transmitted is taken out from the queue of transmission of flow media data, by the forwarding mechanism of BSS,
Determine it is to call " reliable " service to send, or call " best-effort " clothes according to the generated time of each beam
Business is sent.Meanwhile determining which beam needs retransmits according to the acknowledgement frame of receiving terminal (ACK), the queue of transmission is added
In.
Step c：If calling " reliable " service, (multiple beam convergences are at one after the convergence by convergence-level
Block block), it is transferred out by TCP or " red " LTP.If " best-effort " service is called, by convergence-level
Convergence after (multiple beam convergences are at a block block), then call correcting and eleting codes process coded portion.
Step d：Correcting and eleting codes process encodes；" best-effort " services the transmission that can also handle acknowledgement frame, so sentencing first
Whether disconnected is data message (data segment).If data rather than acknowledgement frame, then cutting first is carried out to data block, then made
Redundant data is generated with correcting and eleting codes.This all data is all added into head, head includes that correcting and eleting codes decode and restore out of order number
According to required information), be then packaged as UDP messages and call UDP socket transmissions.
4) data process is received.
Step a：When receiving terminal is when upper level applications initiate new streaming medium content reception request, receiving terminal can be in number
After being opened according to the background process in library, the caching address (buffer) and the length of caching of reception are confirmed.
Step b：When the socket of " best-effort " service receives data, put it into caching first.And judge
It is acknowledgement frame (ACK) or data message (data segment).If it is data message, then by calling under caching mechanism
Come, for decoding use later.
Step c：After receiving enough data, initial data is decoded using correcting and eleting codes, at this moment should be one
Complete block (block), then give on convergence-level, then handle next piece.If the data lost cannot be restored,
Then the block is entirely abandoned, then handles next piece.Response (ACK) frame announcement can be sent after having handled a certain number of block
Know that the transmission situation for sending end data, which data need to retransmit.Inform that " reliable " service prepares to retransmit this data simultaneously.
Step d：The data that " reliable " service receives split into original beam in convergence-level after confirmation is errorless, pass
Enter upper-layer protocol beam protocol layer (bundle protocol layer), while sending acknowledgement frame (ACK).Beam protocol layer can basis
Lane database is written in the creation time of beam (bundle).
Step e：Protocol convergence layer receives the block that step 3 receives, and cutting is original beam, then according to the generation of beam when
Between, it is passed to beam protocol layer (bundle protocol layer), then arrive application program, is played back in real time in receiving terminal.Together
When, application program can copy one and backup to corresponding position in database, for playing back use later.Final data library can store
This time partial data of service.
Third walks：The end of transmission stage.After transmitting terminal receives the last one acknowledgement frame (ACK), all data transmissions are complete
At.After all streams are all closed, the connection closed of both-end.
Correcting and eleting codes are added in " best-effort " service layer of BSS, by the data for increasing redundancy so that receiving terminal has
There is certain error correcting capability, " best-effort " service layer of the transport layer of BSS transmission plans is added in correcting and eleting codes, relative to chain
The bottoms such as road floor coding has stronger error correcting capability；
Pass through the redesign to packet structure so that include sequence in the data message of " best-effort " service
Information；Pass through design caching mechanism so that the data of the same data block (Block) being ranked sequentially according to transmission,
And cache, it is decoded after collecting enough data so that the out of order data of the same data block can be played back orderly.
Erasure code, which is added, in transport layer can restore the data packet (transport layer message Segment) of length bigger, have
Stronger error correcting capability.
Correcting and eleting codes (erasure code) are added on the level of the transport layer；Wherein, the agreement that transport layer uses has：UDP,TCP,
Tetra- kinds of " green " LTP, " red " LTP agreements；Wherein UDP, " green " LTP are serviced for " best-effort "；TCP and
" red " LTP is serviced for " reliable ", and the agreement that suitable transport layer uses is selected according to actual application scenarios.
Correcting and eleting codes are added in " reliable " service, " reliable " of transport layer protocol is serviced, because retransmitting
Data be all by " reliable " service；
Correcting and eleting codes are used for the transport layer of line service agreement (BSS) transmission plan so that an end node to be via Deep Space Network
When network transmits the streaming media resources such as video, there is the ability of local recovery to the data packet of loss；It retransmits, is promoted to reduce
Efficiency of transmission under deep space communication network reduces the delivery time；Meanwhile by designing caching mechanism and data in receiving terminal
The redesign of pack arrangement solves the problems, such as that out of order data influence receiving terminal plays in real time, improves the property of real-time streaming service
Can, wherein：
(1) efficiency of transmission being lifted under deep space communication network is the recovery capability by correcting and eleting codes, can be in receiving terminal
Recover the packet of loss so that the data retransmitted is needed to greatly reduce.The effective delivery time for reducing flow data；
(2) correcting and eleting codes are added in the transport layer of BSS, correcting and eleting codes is added compared in link layer or beam protocol layer,
The advantages that correcting and eleting codes, which are added, in transport layer has error correction recovery capability strong, realizes succinctly, and real-time does very well；
(3) it solves the problems, such as that out of order data influence receiving terminal plays in real time, is transmitted for streaming media service and file
The different characteristics of service avoids out of order data by designing the redesign of caching mechanism and packet structure in receiving terminal
So that broadcasting pictures are discontinuous, or even wrong frame occur, phenomena such as interim card.To improve the performance of real-time streaming service.
The improved BSS transmission plans of correcting and eleting codes are applied to deep space flow data to communicate to be lifted under deep space communication network
Correcting and eleting codes are added by " best-effort " service layer in BSS, by the data for increasing redundancy so that receive in efficiency of transmission
End has certain error correcting capability, without ensureing the transmitting of data by retransmitting, especially in deep space communication environment
Under, the round-trip delay of link is very big, is retransmitted by reducing, can effectively reduce the delivery time, improves efficiency of transmission.Together
When, it can be higher in the bit error rate, packet loss mistake is wrapped in more deep space environment, goes out the real-time Transmission of loss in receiving terminal local recovery
Flow data, greatly promoted real-time streaming data transmission quality.
Correcting and eleting codes are added in the transport layer of BSS transmission plans, have stronger error correction relative to the bottoms such as link layer coding
Ability.And encoded relative to being added in beam protocol layer, waiting is too long when transport layer addition correcting and eleting codes need not decode, and real-time is more
By force, reduce the additional function such as rearrangement of beam so that the realization of scheme is more succinct and robust.
Pass through the redesign to packet structure so that include sequence in the data message of " best-effort " service
Information.Pass through design caching mechanism so that the data of the same data block (Block) being ranked sequentially according to transmission,
And cache, it is decoded after collecting enough data so that the out of order data of the same data block can be played back orderly.
It avoids out of order data influence to play in real time, to improve the performance of real-time streaming service.
The present invention is a kind of highly efficient stream media transmission method for deep space environment.By the way that correcting and eleting codes are transmitted for BSS
In scheme so that new agreement has error correcting capability, improves the efficiency of transmission of stream medium data.Simultaneously by redesigning number
According to pack arrangement and design caching mechanism so that out of order data packet in a certain range can also be reordered and pass through solution
Code recovers, and promotes real-time Transmission quality.In addition, the present invention correcting and eleting codes is added in the transport layer of BSS transmission plans.This is
Because being encoded relative to bottoms such as link layers, coding, which is added, in transport layer can restore data packet (the transport layer report of length bigger
Literary Segment), there is stronger error correcting capability.On the other hand, if correcting and eleting codes are added in beam protocol layer, because of beam protocol layer
Data cell it is excessive, need decoding when wait for the long period, be unfavorable for real-time performance.In addition, the addition of beam protocol layer is entangled and is deleted
Code needs more additional functions realizations, such as the rearrangement etc. of beam.Therefore correcting and eleting codes are added compared to other protocol layers,
The advantages that correcting and eleting codes, which are added, in transport layer has error correction recovery capability strong, realizes succinctly, and real-time does very well.
Correcting and eleting codes (erasure code) can be added in we on the level of the transport layer.Wherein, the agreement that transport layer can use
Have：Tetra- kinds of UDP, TCP, " green " LTP, " red " LTP agreements.Wherein UDP, " green " LTP take for " best-effort "
Business；TCP, " red " LTP are serviced for " reliable ", can select suitable transport layer protocol according to actual application scenarios.
(1) correcting and eleting codes are added in " reliable " service
For the transport layer protocol of " reliable " service, because the data retransmitted are serviced by " reliable "
, and the reliable mechanism of the agreement TCP and " red " LTP of " reliable " service can ensure the complete transmission of data, therefore entangle
Code is deleted to be not essential.
(1) correcting and eleting codes are added in Transmission Control Protocol：
If correcting and eleting codes are added on Transmission Control Protocol, the case where for repeatedly retransmitting, correcting and eleting codes, which are added, effectively to be reduced
Number of retransmissions reduces the delivery time of flow data.For real-time transmission performance, passed because being serviced by " reliable "
Defeated data do not appear in real-time playing program, so correcting and eleting codes, which are added, to have an impact real-time performance.For reality
For existing complexity, because adding correcting and eleting codes, therefore need to make certain change to acknowledgement frame (ACK) mechanism of TCP, in addition
The problem of also coping with out of order data.It should take the circumstances into consideration to consider whether to be added according to specific scene in actual use.
(2) correcting and eleting codes are added in " red " LTP agreements：
If correcting and eleting codes are added on " red " LTP, with TCP with similar in terms of implementation complexity and real-time performance
Feature.In addition to this, for TCP, the mechanism of acknowledgement frame is carried " red " LTP by convergence-level adapter (CLA) on LTP
For realizing simple compared with Transmission Control Protocol.Moreover, multiple sessions (session) parallel transmission of LTP compared to TCP have it is higher
Bandwidth availability ratio is more applicable for the data transmission of deep space scene.
(2) correcting and eleting codes are added in " best-effort " service
For the transport layer protocol of " best-effort " service, because UDP and " green " LTP agreements do not ensure reliably
Property.Therefore correcting and eleting codes, which are added, can improve the reliability of transmission, reduce the number that stream medium data retransmits.For real-time
Speech is added correcting and eleting codes in " best-effort " service, can recover the data lost in real-time Transmission, enhances in real time
The performance of transmission.In addition, because of the transmission of " best-effort " service orientation real time flow medium, it is therefore desirable to realize additional
Ensure the function of order.For implementation complexity, the response frame mechanism of " best-effort " has convergence-level adapter real
It is existing, therefore compared to the Transmission Control Protocol of " reliable " service, " best-effort " service realizes that correcting and eleting codes are more succinct.
(1) correcting and eleting codes are added in " green " LTP agreements：
If correcting and eleting codes are added on " green " LTP, because using multiple sessions (session) parallel transmission, therefore phase
Higher than in udp protocol bandwidth availability ratio, efficiency of transmission is more preferable.But due to multiple session parallel transmissions, out of order possibility is more
Greatly, bad for the guarantee of real time data order, need the function of realizing the guarantee order more more complicated than UDP.
(2) correcting and eleting codes are added in udp protocol：
If correcting and eleting codes are added on UDP, because of the parallel transmission without carrying out multiple sessions, UDP is ensureing have
It is more preferable than " green " LTP in terms of sequence, the function of complicated guarantee order is not needed, correcting and eleting codes implementation complexity is minimum, because
This robustness is also more preferable.
Therefore it should take the circumstances into consideration to consider that UDP is still added on " green " LTP in conjunction with scene and actual conditions in actual use
Correcting and eleting codes.
Advantageous effect：The present invention proposes a kind of highly efficient stream media transmission method for deep space communication network.1) it is promoted
Efficiency of transmission under deep space communication network is the recovery capability by correcting and eleting codes, and the packet of loss can be recovered in receiving terminal,
So that the data retransmitted is needed to greatly reduce.The effective delivery time for reducing flow data；
2) correcting and eleting codes are added in the transport layer of BSS, correcting and eleting codes is added compared in link layer or beam protocol layer, are passing
The advantages that correcting and eleting codes, which are added, in defeated layer has error correction recovery capability strong, realizes succinctly, and real-time does very well；
3) it solves the problems, such as that out of order data influence receiving terminal plays in real time, is for streaming media service and file transmission clothes
The different characteristics of business, by designing the redesign of caching mechanism and packet structure in receiving terminal, avoiding out of order data makes
Broadcasting pictures are discontinuous, or even there is wrong frame, phenomena such as interim card.To improve the performance of real-time streaming service.
Correcting and eleting codes are applied in the transport layer of line service agreement (BSS) transmission plan by the present invention so that an end node
When transmitting the streaming media resources such as video via deep space network, the ability of local recovery is increased, retransmits, is lifted to reduce
Efficiency of transmission under deep space communication network reduces the delivery time, while also optimizing the performance of real-time streaming service, improves in real time
The quality of transmission.Meanwhile the problem of being played in real time for out of order data influence receiving terminal, by the way that caching machine is arranged in receiving terminal
The redesign of system and packet structure so that out of order data packet in a certain range can be also reordered and extensive
It appears again and, ensure the order of data, enable the real-time broadcasting smoothness of receiving terminal without interim card.
Correcting and eleting codes are applied to the transmission layer method of BSS transmission plans, are obtained by increase redundant data appropriate certain
Data recovery capabilities；To reduce the expense for retransmitting data, to improve the efficiency of transmission under deep space environment；By in realization
For Stream Data Transmission real-time and order the characteristics of, by redesign packet structure, the sequence of data transmission is added
Column information, while designing caching mechanism and the message for belonging to the same data block is resequenced, it ensure that the order of transmission, carry
The quality of real-time Transmission is risen；More traditional BSS flow-medium transmission methods have preferable performance boost.
Description of the drawings
Fig. 1 is typical application scenarios；
Fig. 2 is the combination of protocols frame diagram of scheme；
Fig. 3 is the structure of data packet of the present invention；
Fig. 4 is correcting and eleting codes flow chart；
Fig. 5 is transmission process flow chart.
Specific implementation mode
The present invention is further described for explanation and specific implementation mode below in conjunction with the accompanying drawings.
It please refers to Fig.1 to Fig. 5, the present invention provides a kind of highly efficient stream media transmission methods of deep space communication network, below
Its principle and embodiment is described in detail.
The purpose of the invention is in deep space communication network provide streaming media service when, improve transmission efficiency and
Optimize the quality of real-time Transmission.Below with the Mars probes service end node A and distal end ground-based server in scene shown in Fig. 1
Node motion customer end B illustrates the embodiment of transmission method by satellite link since connection to disconnection, we are with Reed-
Solomon (RS) codings illustrate the specific implementation mode of correcting and eleting codes in the present invention as an example.
As shown in Figure 1, an Information Mobile Service end A needs to complete to distal end ground node motion by deep space information network
The access of customer end B.Information Mobile Service end A is linked into terrestrial space information network, after by space link, accesses and is in ground
Mobile client B.
As shown in Fig. 2, the block schematic illustration of the combination of protocols of transmission plan.
In Fig. 2, bssStreamingApp：The transmission function of application layer BSS；
bssRecv：The receiver function of application layer BSS；
BSS forwarder：BSS transponders；
BP forwarder：BP transponders；
Best-effort service：Best effort service；
Reliable service：Reliable service；
AOS：Advanced Orbiting Systems (Advanced Orbiting System)
Correcting and eleting codes (erasure code) can be added in we on transport layer.Transport layer can use " best-
The UDP of effort " services, ' green ' LTP or the TCP of " reliable " service, ' red ' LTP, or both are added.
In this Sample Scenario, the combination of protocols of beam protocol layer and transport layer that we select for：Shu Xieyi, BSS
Forwarder (bssfw), convergence-level adapter (convergence layer adapter), code layers of TCP, RS (is added in
On UDP), UDP.
As shown in figure 3, in the present invention, the data packet of transmission is divided into two big parts of packet header and data payload.
Data packet header includes：
● block number (Block ID)：8 bytes, flag bit are responsible for pointing out to belong to that block；
● sub-block number (sub-Block ID)：1 byte, the serial number of mark RS codings, for resequencing and decoding.
Load includes：
● the heads UDP；
● UDP is loaded.
Fig. 4 is the flow chart of coded portion.
As shown in figure 5, the transmission method for implementing the present invention is broadly divided into following steps：
The first step：The transmission start stage.Including establishing connection and initialization data library.
Step a：Carry out streaming media, it is necessary first to establish connection, confirm the Termination ID (endpoint ID) of both sides when
When client is connect with server, since BSS can be transmitted using to " reliable " service to ensure reliability.If
Transmission Control Protocol is used under " reliable " service, then needs to shake hands for 3 times, if used under " reliable " service
" red " ltp agreements, then need not generally shake hands, but the data packet of an initialization connection is sent by transmitting terminal, then receive
End can postback an acknowledgement frame (ACK) after several data segments (segment) and inform the case where transmitting terminal receives.
Step b：The background process of a database can be opened in receiving terminal, and confirms that database can be opened.Then it sets
" WINDOW " option is set, the playback duration of bss databases can be arranged in this option, be defaulted as 86400 seconds, i.e., one day.This into
Journey can be by all data received, either in real time, or retransmit, according to the generated time of packet it is orderly be stored in number
According to inside library, needed so that future plays back.In order to normally use future database, user to need to provide 3 parameters：Number
According to library name, the ID (endpoint ID) of data storage address, terminal.
Database includes the file of 3 kinds of formats：Table (table), row (list), data (data).Respectively with " .tbl ",
The name of " .lst ", " .dat " ending.
Data storage address is the address of above-mentioned 3 files, and 3 files need to be placed in a catalogue.
Termination ID determines data will be sent to where.
Second step：Transmission data.Including transmission data and receiving two processes of data：
(1) transmission data process.
Step a：When upper layer application initiates new streaming medium content reception request, transmitting terminal can will need the stream matchmaker that transmit
Volume data is written to sequentially in time in the beam (bundle) of beam protocol layer (bundle protocol layer).Each beam
The generated time of beam can also be recorded.
Step b：Next beam to be transmitted is taken out from the queue of transmission, as shown in Fig. 2, agreement will be turned by following
Hair mechanism ensures order transfer：
Each beam to be sent is compared with the generated time of the beam sent before.If small than before, explanation is
The packet of re-transmission, " reliable " service of calling are sent.If big than before, explanation is normal packet in real time, is called
" best-effort " service is sent.
Meanwhile determining which beam needs retransmits according to the acknowledgement frame of receiving terminal (ACK), it is added in the queue of transmission.
Step c：If calling " reliable " service, (multiple beam convergences are at one after the convergence by convergence-level
Block block), it is transferred out by TCP or " red " LTP.If " best-effort " service is called, by convergence-level
Convergence after (multiple beam convergences are at a block block), then call correcting and eleting codes process coded portion.
Step d：As shown in figure 4, the coded portion of correcting and eleting codes process.We are by taking Reed-Solomon is encoded as an example.Because
" best-effort " services the transmission that can also handle acknowledgement frame, so it is first determined whether being data message (data
segment).If data rather than acknowledgement frame, then start the part of RS (n, k) codings：
● by block cutting be k fritter (sub-block).
● and then the fritter of (n-k) a redundancy is generated using RS codings.
● this n fritter is all added to head (head includes the required information of RS coding and decodings), the information on head is such as
Shown in Fig. 3, block number (Block ID) (8 bytes) and block number (sub-Block ID) (byte) are contained.
● it is then packaged as UDP messages and calls UDP socket transmissions.
(2) data process is received.
Step a：When upper layer application initiates new streaming medium content and receives request, receiving terminal can the backstage of database into
After journey is opened, the caching address (buffer) and the length of caching of reception are confirmed.
Step b：When the socket of " best-effort " service receives data, put it into caching first.And judge
It is acknowledgement frame (ACK) or data message (data segment).It if it is data message, then caches, for decoding later
It uses.
Step c：The reception flow of " best-effort " service.
● the data of UDP socket are often received, are just stored in the UDP cachings of decoding end.
● the head currently wrapped is taken out, is checked with whether a upper sub-block is that identical block number (block ID) judges to be somebody's turn to do
Whether sub-block (sub-block) belongs to current block (block).If it is current block, then continuing to.And according to sub-block
Number order deposit caching corresponding position.
● if not current block, then judge whether the sub-block number of the same block received is more than k, illustrates energy
The data for enough recovering original entire block, are decoded., whereas if less than k, then illustrates that the block cannot be decoded, lose
The block is abandoned, an acknowledgement frame is replied.
● it checks whether decoding succeeds, recovers data if failing, abandon the block, then handle next piece.If
Can successfully by initial data decode come, at this moment should be a complete block (block), then give on convergence-level, connect
Next piece of processing.The transmission feelings that response (ACK) frame informs transmission end data can be sent after having handled a certain number of block
Condition, which data need to retransmit.Inform that the transmission queue of beam prepares to retransmit the beam simultaneously.
Step d：The data that " reliable " service receives split into original beam in convergence-level after confirmation is errorless, pass
Enter upper-layer protocol beam protocol layer (bundle protocol layer), while sending acknowledgement frame (ACK).Beam protocol layer can basis
Lane database is written in the creation time of beam (bundle).
Step e：Protocol convergence layer receives the block that step 3 receives, and cutting is original beam, then according to the generation of beam when
Between, it is passed to beam protocol layer (bundle protocol layer), then arrive application program, is played back in real time in receiving terminal.Together
When, application program can copy one and backup to corresponding position in database, for playing back use later.Final data library can store
This time partial data of service.
Third walks：The end of transmission stage.After transmitting terminal receives the last one acknowledgement frame (ACK), all data transmissions are complete
At.After all streams are all closed, the connection closed of both-end.
Working mechanism of the present invention, two nodes in deep space communication network, one end access another node as client,
When carrying out the transmission of multimedia messages, using this method, when packet loss mistake packet occurring in satellite link, it can effectively restore data,
The expense retransmitted is reduced, the efficiency of transmission under deep space environment is improved；The multimedia transmission method of more traditional BSS associations, Neng Gouyou
Effect ground promotes the transmission quality of real time data, reduces the delivery time of data.
It is described in detail in conjunction with the specific example of deep space communication network by introducing correcting and eleting codes and caching when the above content
Mechanism realizes principle and the effect of efficient multimedia transmission method.It cannot be assumed that the specific implementation of the present invention is confined to these and says
It is bright.It for those of ordinary skill in the art to which the present invention belongs, without departing from the inventive concept of the premise, can be with
Several deduction or replace are made, protection scope of the present invention is all should be considered as.
Claims (3)
1. a kind of highly efficient stream media transmission method for deep space environment, which is characterized in that
Correcting and eleting codes are used for the transport layer of line service agreement BSS transmission plans so that an end node to be transmitted via deep space network
When streaming media resource, there is the energy of local recovery to the data packet of loss；Meanwhile by designing caching mechanism, number in receiving terminal
Out of order data are solved according to the redesign of pack arrangement, below the highly efficient stream media transmitting step of deep space environment：
The first step：The transmission start stage；It is connected firstly the need of establishing, when client is connect with server, since BSS can be used
It is transmitted to " reliable " service to ensure reliability；If using Transmission Control Protocol under " reliable " service, need
It wants to shake hands for 3 times, if using " red " ltp agreements under " reliable " service, need not shake hands, but be sent out by transmitting terminal
The data packet of an initialization connection is sent, then receiving terminal can postback an acknowledgement frame after several data segments (segment)
(ACK) the case where transmitting terminal receives is informed；In addition, the background process of a database can be opened in receiving terminal, and confirm data
Library can open；This process can by all data received, either in real time, or retransmit, according to the generation of packet
Time is orderly to be stored in inside database, so that playback in future needs；
Second step：Transmission data；Including transmission data and receiving two processes of data：
1) transmission data process；
Step a：When transmitting terminal is received when upper level applications initiate new streaming medium content and receive request, transmitting terminal can need to
The stream medium data to be transmitted is written to the beam of beam protocol layer (bundle protocol layer) sequentially in time
(bundle) in；Each beam can also record the generated time of beam；
Step b：Next beam to be transmitted is taken out from the queue of transmission of flow media data, by the forwarding mechanism of BSS, according to
It is to call " reliable " service to send, or call " best-effort " service hair that the generated time of each beam, which determines,
It sees off；Meanwhile determining which beam needs retransmits according to the acknowledgement frame of receiving terminal (ACK), it is added in the queue of transmission；
Step c：If calling " reliable " service, (multiple beam convergences are at a block after the convergence by convergence-level
Block), transferred out by TCP or " red " LTP；If " best-effort " service is called, by convergence-level
After convergence (multiple beam convergences are at a block block), correcting and eleting codes process coded portion is then called；
Step d：Correcting and eleting codes process encodes；" best-effort ", which is serviced, can also handle the transmission of acknowledgement frame, thus first determine whether be
No is data message (data segment)；If data rather than acknowledgement frame, then cutting first is carried out to data block, then using entangling
It deletes code and generates redundant data；This all data is all added into head, head includes that correcting and eleting codes decode and restore out of order data institute
The information that needs), it is then packaged as UDP messages and calls UDP socket transmissions；
2) data process is received；
Step a：When receiving terminal is when upper level applications initiate new streaming medium content reception request, receiving terminal can be in database
Background process open after, confirm the caching address (buffer) and the length of caching of reception；
Step b：When the socket of " best-effort " service receives data, put it into caching first；And judge to be to answer
Answer frame (ACK) or data message (data segment)；If it is data message, then by calling caching mechanism to get off, supply
Decoding uses later；
Step c：After receiving enough data, initial data is decoded using correcting and eleting codes, at this moment should be one complete
Block (block), then give on convergence-level, then handle next piece；It, will if the data lost cannot be restored
The block entirely abandons, and then handles next piece；Response (ACK) frame can be sent after a certain number of block by, which having handled, informs hair
The transmission situation of sending end data, which data need to retransmit；Inform that " reliable " service prepares to retransmit this data simultaneously；
Step d：The data that " reliable " service receives split into original beam in convergence-level after confirmation is errorless, are passed to
Layer protocol beam protocol layer (bundle protocol layer), while sending acknowledgement frame (ACK)；Beam protocol layer can be according to beam
(bundle) lane database is written in creation time；
Step e：Protocol convergence layer receives the block that step 3 receives, and cutting is original beam, then according to the generated time of beam, is passed
Enter beam protocol layer (bundle protocol layer), then arrive application program, is played back in real time in receiving terminal；Meanwhile it applying
Program can copy one and backup to corresponding position in database, for playing back use later；Final data library, which can store, this time to be taken
The partial data of business；
Third walks：The end of transmission stage；After transmitting terminal receives the last one acknowledgement frame (ACK), all data transmissions are completed；?
After all streams are all closed, the connection closed of both-end.
2. the highly efficient stream media transmission method according to claim 1 for deep space environment, which is characterized in that
Take the circumstances into consideration to consider that still correcting and eleting codes are added on " green " LTP in UDP in conjunction with scene and actual conditions.
3. the highly efficient stream media transmission method according to claim 1 for deep space environment, which is characterized in that for
The transmission of " best-effort " service orientation real time flow medium needs the function of realizing additional guarantee order, " best-
The response frame mechanism of effort " has the realization of convergence-level adapter.
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