CN103780345A - System and method for multi-buffering non-constant-speed code transmission of real-time service in intensive communication - Google Patents

Abstract

The invention discloses a system and method for multi-buffering non-constant-speed code transmission of real-time service in intensive communication. The system comprises a coding terminal, at least two communication links and a decoding terminal, wherein the coding terminal sequentially conducts LT code coding on a plurality of information groups formed by dividing a video streaming so that a plurality of groups of multi-buffing LT codes can be obtained, and the obtained multi-buffering LT codes are sent by the coding terminal; the decoding terminal conducts LT code decoding on all the groups of multiple-buffering LT codes which are received accumulatively, so that corresponding information groups are obtained, and corresponding decoding buffering zones are emptied; when one communication link breaks down, other communication links are adopted to conduct data transmission through switching or other communication links and the communication link which breaks down are selected to conduct data communication at the same time. According to the system for multi-buffering non-constant-speed code transmission of the real-time service in intensive communication, when feedback links are not ideal in intensive communication, for example, the delay of one feedback link is long or the upstream link and the downstream link do not correspond to each other, real-time data can be transmitted efficiently and reliably; due to the feature of the non-constant speed codes, switching between the communication links is smoother.

Description

Multi-buffer non-constant-speed code transmission system and method for real-time services in intensive communication

technical field

The invention relates to the technical field of wireless communication, in particular to a multi-buffer non-constant-speed code transmission system and method for real-time services in intensive communication.

Background technique

Mobile communication is an important infrastructure of the information society, and the development of broadband wireless mobile communication is the basic strategic demand of our country. At the same time, with the great enrichment of cultural life of our people in the information society and the popularization of smart phones, tablets, and laptops, the mobile data business volume has almost exponentially increased. On the other hand, with the acceleration of urbanization in our country, the degree of urban population density is constantly upgrading, and due to the limitation of land resources, the development of modern cities is shifting from flat extension to three-dimensional extension, which also makes the number of mobile users per unit area With the linear increase of floor and terrain height, it shows an unprecedented densification trend, which poses a great challenge to the spectral efficiency of mobile communication per unit area. Therefore, the three-dimensional dense coverage network for mobile users has become the development trend of the future metropolitan wireless communication network.

In the wireless network environment with three-dimensional dense coverage, mobile multimedia applications will continue to increase, which will put forward higher requirements for wireless real-time data services such as real-time video transmission quality. However, most of the literature and patents at home and abroad only consider the design and research of non-constant-rate coding under ideal feedback channels. Therefore, there is an urgent need for a real-time service transmission system that can effectively resist the feedback channel non-ideality.

Contents of the invention

One of the technical problems to be solved by the present invention is to provide a multi-buffer non-constant-speed code transmission system for real-time services in intensive communication, which can effectively resist the non-ideality of the feedback channel. In addition, a multi-buffer non-constant-speed code transmission method for real-time services is also provided.

In order to solve the above-mentioned technical problems, the present invention provides a multi-buffer non-constant-speed code transmission system for real-time services in intensive communication, including: a coding end, which is provided with a plurality of coding buffers, and utilizes a plurality of coding buffers to process video streams The divided information groups are sequentially encoded with LT codes to obtain multiple groups of multi-buffer LT codes, and the obtained groups of multi-buffer LT codes are sent sequentially, and the information groups in the corresponding coding buffers are updated in combination with the decoding feedback information; The transmission medium includes at least two communication links for real-time transmission of each group of multi-buffered LT codes; the decoding end is provided with multiple decoding buffers, and each group of multi-buffered LT codes accumulated and received by each decoding buffer is used. code to perform LT code decoding so as to obtain the corresponding information group, send the decoding feedback information about the group of multi-buffered LT codes back to the encoding end, and clear the corresponding decoding buffer, wherein, when a communication link has a problem, Then switch to another communication link for data transmission, or select another communication link to perform data transmission simultaneously with the communication link.

In one embodiment, the communication link communicates through a non-link-oriented reliable transmission protocol, wherein the non-link-oriented reliable transmission protocol is based on an erasure channel composed of UDP packets and CRC checks and multi-buffered LT codes. The encoding and decoding methods are obtained.

In one embodiment, the encoding end further includes: a division unit, which is used to divide the video stream into several information groups of equal length, and sort each information group in turn to form an encoding queue, and divide the previously set number of information Groups are put into each encoding buffer in turn, wherein, the number of information groups of the set number is the same as the number of encoding buffers, and each information group is divided into K LT packets of equal length; LT code encoding unit, which performs LT code encoding on the K LT data packets in the encoding buffer currently pointed to by the encoding pointer to obtain p encoding packets, and sends the obtained p encoding packets in sequence, and then points the encoding pointer to the next encoding Buffer, if the current encoding pointer points to the last encoding buffer, then the encoding pointer points to the first encoding buffer, wherein the number p of encoded packets is less than the number K of LT data packets; During the encoding process, it is used to judge whether the decoding feedback information from the decoding end is received. If the decoding feedback information is received, the first group of information that is not placed in the encoding buffer and is located at the head of the encoding queue Put it into the encoding buffer corresponding to the decoding feedback information, otherwise return to the LT code encoding unit to continue to perform LT code encoding on the encoding buffer currently pointed to by the encoding pointer.

In one embodiment, the decoding end further includes: a receiving unit, configured to, when receiving an encoded packet, put it into a corresponding decoding buffer according to the encoding buffer information obtained from the header information of the encoded packet In the area; LT code decoding unit, when the total number of the encoded packets received by it in a certain decoding buffer is greater than K, the encoded packets in the decoding buffer are decoded by LT code, if the decoding is successful, then the decoding will be obtained Put the information group into the tail of the decoding queue and send decoding feedback information to the encoding end, otherwise the decoding buffer will continue to receive p encoding packets sent by the corresponding encoding buffer, and perform The LT code is decoded until the decoding is successful.

According to another aspect of the present invention, there is also provided a multi-buffer non-constant-speed code transmission method for real-time services in intensive communication, including: an encoding step, setting a plurality of encoding buffers, and using the plurality of encoding buffers to process the video streams The divided information groups are sequentially encoded with LT codes to obtain multiple groups of multi-buffer LT codes, and the obtained groups of multi-buffer LT codes are sent sequentially, and combined with the decoding feedback information to update the corresponding information groups in the coding buffer; Step, real-time transmission of each group of multi-buffer LT codes through the communication link; Decoding step, a plurality of decoding buffers are set, and each group of multi-buffer LT codes received by each decoding buffer is used to decode the LT codes to obtain the corresponding Information group, sending the decoding feedback information about the group of multi-buffered LT codes to the encoding end, and clearing the corresponding decoding buffer, wherein there are at least two communication links, and when a communication link has a problem , switch to another communication link for data transmission, or select another communication link to perform data transmission simultaneously with the communication link.

In one embodiment, in the transmission step, the communication link communicates based on a non-link-oriented reliable transmission protocol, wherein the non-link-oriented reliable transmission protocol is based on the deletion of UDP packets and CRC checks. Channel and multi-buffered LT code encoding and decoding methods are obtained.

In one embodiment, the encoding step further includes: step 710, dividing the video stream into several information groups of equal length, sorting each information group in turn to form an encoding queue, and converting the previously set number of information Groups are put into each encoding buffer successively, wherein, the number of information groups of the set quantity is identical with the number of encoding buffers, and each information group is divided into K LT data packets equal in length; Step 720, Carry out LT code encoding to the K LT data packets in the encoding buffer currently pointed to by the encoding pointer to obtain p encoding packets, and send the obtained p encoding packets in sequence, then point the encoding pointer to the next encoding buffer, If the current encoding pointer points to the last encoding buffer, then the encoding pointer is pointed to the first encoding buffer, wherein the number p of encoded packets is less than the number K of LT data packets; step 730, in the LT code encoding process, Judging whether to receive decoding feedback information from the decoding end, if receiving the decoding feedback information, put the first group of information that is not placed in the buffer and is located at the head of the encoding queue into the decoding feedback Otherwise, return to step 720 and continue to perform LT code encoding on the encoding buffer currently pointed to by the encoding pointer.

In one embodiment, the decoding step further includes: step 810, when receiving the encoded packet, put it into the corresponding decoding buffer according to the encoding buffer information obtained from the header information of the encoded packet In the district; step 820, when the total number of the coded packets received in a certain decoding buffer is greater than K, carry out LT code decoding to the coded packets in the decoding buffer, if the decoding is successful, then the information group obtained by decoding Put it at the end of the decoding queue and send decoding feedback information to the encoding end, otherwise the decoding buffer will continue to receive p encoded packets sent by the corresponding encoding buffer, and perform LT code decoding on all the encoded packets it receives , until the decoding is successful.

In one embodiment, the transmission rate of the multi-buffer LT code is:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; di</span>}}<span\; class="notranslate">\; )</span>}$

Among them, l is the total number of information groups, K is the number of LT data packets with the same length in each information group, P _m is the size of LT data packets, and s _i is the multi-buffer received before the ith information group is successfully decoded The number of groups of LT codes, p is the number of encoded packets generated by each information group, t _c is the transmission time corresponding to a group of multi-buffered LT codes corresponding to the transmission data link, t _di is the feedback information after decoding the i-th information group The time required to reach the decoder.

In one embodiment, under the premise that max{t _di }<pmt _c -1 is satisfied, the transmission efficiency of the multi-buffer LT code is:

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}$

Wherein, m is the number of encoding buffers, R is the actual transmission speed of the transmission data link, and E(s) is the expectation of the number of sets of multi-buffered LT codes received before successful decoding.

Compared with the prior art, one or more embodiments of the present invention may have the following advantages:

The multi-buffer non-constant-speed code transmission system of the present invention encodes and decodes data based on non-constant-speed codes, and includes at least two communication links to transmit information, which ensures the accuracy of data transmission when a link has a real-time failure Continuity; due to the use of the encoding buffer and the decoding buffer, the multi-buffer non-constant speed code of the present invention better overcomes the delay characteristics of the non-constant code, so the system can feedback link delays in dense communications. Efficient and reliable transmission of real-time data when there is a large amount of time or when the uplink and downlink unequal feedback links are not ideal, and the switching between communication links is smoother.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the attached picture:

1 is a block diagram of a multi-buffer non-constant-speed code transmission system for real-time services in dense communications according to an embodiment of the present invention;

Fig. 2 is the flow chart of the encoding method based on multi-buffer LT code according to an example of the present invention;

Fig. 3 is a flow chart of a decoding method based on multi-buffer LT codes according to an example of the present invention;

Fig. 4 is a comparison diagram between the transmission efficiency of the multi-buffering non-constant-speed code transmission system of real-time services in intensive communication and the transmission efficiency of other systems under the condition that the feedback link has a delay according to an example of the present invention;

Fig. 5 is a frame diagram of a multi-buffer non-constant-speed code transmission system for real-time services in intensive communication according to an example of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a block diagram of a multi-buffer non-constant-speed code transmission system for real-time services in intensive communication (hereinafter referred to as a multi-buffer non-constant-speed code transmission system) according to an embodiment of the present invention, and Fig. 5 is a multi-buffer according to an example of the present invention The frame diagram of the non-constant-speed code transmission system, the following takes the transmission of video files as an example, and describes in detail how the system performs data transmission in combination with the attached drawings.

It can be seen from FIG. 1 that the multi-buffer non-constant-speed code transmission system mainly includes an encoding end 10 , a transmission medium 20 and a decoding end 30 .

The encoding end 10 is used to convert the file to be transmitted into a video stream, and encode the obtained video stream based on a non-constant-rate encoding method. For example, a video file can be acquired by a camera acquisition device (such as a video camera), and the acquired video file can be encoded by VLC video stream by calling the LibVLC library function, so as to obtain a video stream file.

Specifically, the encoding end 10 is provided with a plurality of encoding buffers, and the plurality of encoding buffers are used to sequentially perform LT code encoding on several information groups divided by the video stream to obtain multiple sets of multi-buffer LT codes. The multi-buffer LT codes are sent sequentially, and the corresponding information groups in the coding buffer are updated in combination with the decoding feedback information. The multi-buffer LT code in this embodiment is an improved non-constant speed code. The decoding feedback information mentioned here is an ACK feedback packet.

The encoding end 10 further includes: a dividing unit 11 , an LT code encoding unit 12 and a judging unit 13 . Wherein, the division unit 11 is used to divide the video stream into several information groups of equal length, and sort each information group in turn to form an encoding queue, and put the previously set number of information groups into each encoding buffer in turn, wherein, The set number of information groups is the same as the number of encoding buffers, and each information group is divided into K LT data packets of equal length.

For the LT code encoding unit 12, it carries out LT code encoding to K LT data packets in the encoding buffer currently pointed to by the encoding pointer to obtain p encoded packets, and sends the obtained p encoded packets in sequence, and then, Point the encoding pointer to the next encoding buffer, if the current encoding pointer points to the last encoding buffer, point the encoding pointer to the first encoding buffer, wherein the number p of encoded packets is less than the number K of LT data packets.

The judging unit 13 then judges whether to receive the decoding feedback information from the decoder 10 during the LT code encoding process. The group information group is put into the encoding buffer corresponding to the decoding feedback information, otherwise, return to the LT code encoding unit 12 to continue performing LT code encoding on the encoding buffer currently pointed to by the encoding pointer.

As for the transmission medium 20, it is used for real-time transmission of encoded video streams, and includes at least two communication links. This makes it possible to switch to other communication links for data transmission when a problem occurs in a communication link, or select another communication link to perform data transmission simultaneously with the communication link. For example, if the LTE link increases the total data delay due to the increase of dense users, the transmission direction can be changed and WLAN link transmission is adopted. Due to the importance of non-constant-speed encoded packets, link switching has a relatively high fluency.

Please refer to FIG. 5 , in the example shown in FIG. 5 , the transmission medium 20 includes two links, an LTE link and a WLAN link with a relay station. Preferably, the communication link communicates through a non-link-oriented reliable transmission protocol, wherein the non-link-oriented reliable transmission protocol is obtained based on an erasure channel composed of UDP packets and CRC checks, and multi-buffered LT code encoding and decoding methods. The error control method using multi-buffer LT codes on the deletion channel composed of UDP packets and CRC checks only needs a small amount of calculation overhead to ensure reliable transmission of the system, and has the effect of efficient communication of UDP protocol and non-constant Due to the advantages of high-speed encoding channel rate adaptive matching, low feedback channel pressure in high bit error rate communication environments, and peer-to-peer flow properties of encoded packets, this non-link-oriented reliable transmission protocol can be used in multi-link situations.

The decoding end 30 is provided with a plurality of decoding buffers, utilizes each decoding buffer to carry out LT code decoding to each group of multi-buffering LT codes accumulated therein so as to obtain the corresponding information group, and sends the decoding information about the group of multi-buffering LT codes The feedback information is fed back to the encoding end 10, and the corresponding decoding buffer is cleared. For example, the decoding end 30 receives the video stream file in multi-buffer LT code form from the LTE client and/or WIFI through Ethernet, decodes it, and transmits the decoded file to the VLC player in real time to complete real-time playback demo. Here, the number of decoding buffers may be selected to be greater than the number of encoding buffers, so as to increase the tolerance for delay of feedback information.

In detail, the decoding end 30 further includes: a receiving unit 31 and an LT code decoding unit 32 . Wherein, the receiving unit 31 is configured to put the encoded packet into the corresponding decoding buffer according to the encoding buffer information obtained from the header information of the encoded packet when receiving the encoded packet. For the LT code decoding unit 32, when the total number of the received coded packets in a certain decoding buffer is greater than K, the coded packets in the decoded buffer are decoded by the LT code, and if the decoding is successful, the decoded The obtained information group is put into the tail of the decoding queue, and the decoding buffer is emptied, and in addition, decoding feedback information is sent to the encoding end 10, otherwise the decoding buffer continues to receive p encoded packets sent by the corresponding encoding buffer, And perform LT code decoding on all the coded packets it receives until the decoding succeeds.

From another point of view, the present invention also proposes a multi-buffer non-constant-speed code transmission method, which will be described in detail below in conjunction with the above-mentioned multi-buffer non-constant-speed code transmission system.

First, the encoding end 10 sets a plurality of encoding buffers, uses the plurality of encoding buffers to sequentially perform LT code encoding on several information groups divided by the video stream to obtain multiple groups of multi-buffer LT codes, and converts each group of multi-buffer LT codes obtained Send them sequentially, and update the corresponding information group in the encoding buffer in combination with the decoding feedback information.

FIG. 2 is a flow chart of an encoding method based on multi-buffered LT codes according to an embodiment of the present invention. With reference to FIG. 2 , the encoding end 10 encodes a video stream in detail below.

As shown in step S210, the division unit 11 first divides the video stream into several equal-length information groups, and sorts each information group in turn to form an encoding queue, wherein the previously set number of information groups are sequentially put into each encoding buffer , where the number of information groups of the set number is the same as the number of encoding buffers, and each information group is divided into K LT data packets of equal length. In step S220, the LT code encoding unit 12 performs LT code encoding on the K LT data packets in the encoding buffer currently pointed to by the encoding pointer to obtain p encoded packets, and sends the obtained p encoded packets in sequence, and then, Point the encoding pointer to the next encoding buffer, if the current encoding pointer points to the last encoding buffer, point the encoding pointer to the first encoding buffer, wherein the number p of encoded packets is less than the number K of LT data packets.

In detail, a group of information is divided into K equal-length LT data packets with a length of P bit, and then d data packets are randomly selected for bitwise XOR operation as an LT encoded packet. It can be understood that such data packets and encoding Packages have an adjacency relationship. Among them, d is the encoding degree, which is a random variable. In engineering, the random variable adopts a robust arc distribution:

$\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; K</span>}$

解码最大错误概率，λ是满足 $\frac{1}{K}\frac{\sqrt{K}}{\ln \left(\frac{K}{\mathrm{\&delta;}}\right)}<\mathrm{\&lambda;}<\frac{1}{2}\frac{\sqrt{K}}{\ln \left(\frac{K}{\mathrm{\&delta;}}\right)}$ 的正参量。in: $\mathrm{\&mu;}\left(d\right)=\left\{\begin{array}{cc}\frac{1}{K},& d=1\\ \frac{1}{d(d-1)},& d\&Greater\; Equal;2\end{array}\right.,$ $\left(d\right)=\left\{\begin{array}{cc}\frac{S}{k},& d<\frac{K}{S}\\ \frac{S}{K}\ln \left(\frac{S}{\mathrm{\&delta;}}\right),& d=\frac{K}{S}\\ 0,& d>\frac{K}{S}\end{array}\right.,$ $S=\mathrm{\&lambda;}\ln \left(\frac{K}{\mathrm{\&delta;}}\right)\sqrt{K},$ δ and λ are the parameters of the degree distribution, and δ means when received

The maximum error probability of decoding, λ is to satisfy $\frac{1}{K}\frac{\sqrt{K}}{\ln \left(\frac{K}{\mathrm{\&delta;}}\right)}<\mathrm{\&lambda;}<\frac{1}{2}\frac{\sqrt{K}}{\ln \left(\frac{K}{\mathrm{\&delta;}}\right)}$ positive parameter.

As shown in step S230, the judging unit 13 judges whether to receive the decoding feedback information from the decoding end 30 during the LT code encoding process, and if the decoding feedback information is received, it will not put into the buffer and is located in the encoding queue. Put the first group of information at the head into the encoding buffer corresponding to the decoding feedback information, otherwise return to step S220 and continue to perform LT encoding on the encoding buffer currently pointed to by the encoding pointer. For example, if an ACK feedback packet from a certain decoding buffer is received, the first group of information that is not placed in the buffer and located at the head of the encoding queue is put into the encoding buffer corresponding to the decoding buffer.

Through the above steps, the multi-buffer LT code encoding of the video stream file in the encoding terminal 10 can be completed, and each group of multi-buffer LT codes can be transmitted in real time through the communication link in the transmission medium 20 . Wherein, there are at least two communication links, and when a problem occurs in one communication link, switch to another communication link for data transmission, or select another communication link to perform data transmission simultaneously with the communication link. As mentioned above, the communication link in this embodiment communicates based on the non-link-oriented reliable transmission protocol, which is based on the erasure channel composed of UDP packets and CRC checks and the encoding and decoding methods of multi-buffered LT codes. It is worth noting that if the decoding buffer does not receive all the p encoded packets encoded by the corresponding information groups, for example, only p-2 encoded packets are received, at this time, the decoding end 30 does not send a message to the encoding end 10 Send a request asking it to resend the p encoded packets.

Finally, the decoding end 30 also sets a plurality of decoding buffers, utilizes each decoding buffer to perform LT code decoding on each group of multi-buffering LT codes received accumulatively to obtain a corresponding information group, and sends decoding feedback about the group of multi-buffering LT codes The information is fed back to the encoding end 10, and the corresponding encoding buffer is cleared.

FIG. 3 is a flow chart of a decoding method based on multi-buffered LT codes according to an embodiment of the present invention. With reference to FIG. 3 , the encoding terminal 30 decodes the video stream in detail below. In step S310, the receiving unit 31 firstly puts the encoded packet into the corresponding decoding buffer according to the encoding buffer information obtained from the header information of the encoded packet when receiving the encoded packet. Then, in step S320, when the total number of received coded packets in a certain decoding buffer is greater than K, the LT code decoding unit 32 carries out LT code decoding to the coded packets in the decoded buffer, if the decoding is successful, then Put the decoded information group into the tail of the decoding queue, clear the decoding buffer, and send decoding feedback information to the encoding end 10, otherwise the decoding buffer will continue to receive p encoded packets sent by the corresponding encoding buffer, And perform LT code decoding on all the coded packets it receives until the decoding succeeds.

Specifically, according to the encoding degree information carried in the packet header, an encoded packet with a degree of 1 is found as a decoding node. Since the decoding node is a complete copy of its unique data adjacent packet, this corresponding adjacent data packet can be recovered according to the encoding information. At the same time, bitwise XOR the recovered data packet with all its adjacent coded packets and decrement the degree of these coded packets by 1, and continue to search for coded packets with a degree of 1, if found, repeat the above operation until all K data The packets are all restored, that is, the decoding is successful. If it is not found, it will return the decoding failure, and wait to receive more (the next set of p) packets to decode again.

It can be understood that in this embodiment, the relay complementary link and the multi-buffer LT code are used to reduce the impact on the LT coding performance caused by the delay of the feedback ACK information packet, improve the transmission efficiency of the traditional LT code, and finally provide Stable and reliable data transmission service.

In addition, the multi-buffered LT code of this embodiment has a better transmission rate than the common LT code. The transmission rate of the multi-buffer LT code is calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; di</span>}}<span\; class="notranslate">\; )</span>}$

Among them, l is the total number of information groups, K is the number of LT data packets with the same length in each information group, P _m is the size of LT data packets, and s _i is the multi-buffer received before the ith information group is successfully decoded The number of groups of LT codes, p is the number of encoded packets generated by each information group, t _c is the transmission time corresponding to a group of multi-buffered LT codes corresponding to the transmission data link, t _di is the feedback information after decoding the i-th information group The time required to reach the decoder.

And, under the premise of satisfying max{t _di }<pmt _c -1, the transmission efficiency of multi-buffer LT code transmission:

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}$

Among them, m is the number of encoding buffers, R is the actual transmission speed of the transmission data link, and E(s) is the expected number of groups of multi-buffered LT codes received before successful decoding.

Fig. 4 is a diagram comparing the transmission efficiency of the multi-buffer non-constant-rate code transmission system with the transmission efficiency of other systems under the condition that the feedback link has a delay according to an example of the present invention. It can be seen from Fig. 4 that the transmission efficiency of multi-buffered LT codes in different channels (such as ideal channels, AWGN channels and fading channels) with delay in the feedback link is higher than that of traditional LT codes.

To sum up, the multi-buffer non-constant-speed code transmission system of this embodiment encodes and decodes data based on non-constant-speed codes, and includes at least two communication links to transmit information, which will cause real-time failures in the links. The continuity of data transmission is guaranteed at the same time; due to the use of encoding buffer and decoding buffer, the multi-buffer non-constant speed code of the present invention better overcomes the delay characteristics of non-constant code, so this system can be used in intensive communication When the delay of the feedback link is large or when the uplink and downlink are not equal and the feedback link is not ideal, the real-time data can be transmitted efficiently and reliably, and the switching between communication links is smoother.

The above is only a specific implementation case of the present invention, and the scope of protection of the present invention is not limited thereto. Any skilled person familiar with the technology should modify or replace the present invention within the technical specifications described in the present invention. Within the protection scope of the present invention.

Claims (10)

1. A multi-buffer non-constant-speed code transmission system for real-time services in intensive communications, comprising: Encoding end, it is provided with a plurality of encoding buffers, utilizes a plurality of encoding buffers to carry out LT code encoding sequentially to several information groups divided by the video stream to obtain multiple groups of multi-buffering LT codes, and each group of obtained multi-buffering LT codes Send in sequence, and update the information group in the corresponding encoding buffer in combination with the decoding feedback information; A transmission medium comprising at least two communication links for real-time transmission of each group of multi-buffered LT codes; The decoding end, which is provided with multiple decoding buffers, utilizes each decoding buffer to perform LT code decoding on each group of multi-buffered LT codes received in total to obtain the corresponding information group, and sends the decoding information about the group of multi-buffered LT codes The feedback information is fed back to the encoding end, and the corresponding decoding buffer is cleared, Wherein, when a problem occurs in a communication link, switch to another communication link for data transmission, or select another communication link to perform data transmission simultaneously with the communication link. 2. The multi-buffering non-constant-speed code transmission system according to claim 1, wherein the communication link communicates by a non-link-oriented reliable transmission protocol, wherein the non-link-oriented reliable transmission protocol is based on The erasure channel composed of UDP packets and CRC checks and the encoding and decoding methods of multi-buffer LT codes are obtained. 3. The multi-buffering non-constant-speed code transmission system according to claim 2, wherein the encoding end further comprises: A division unit, which is used to divide the video stream into several information groups of equal length, and sort each information group in turn to form an encoding queue, and put the previously set number of information groups into each encoding buffer in turn, wherein, all The number of information groups of the set quantity is the same as the number of encoding buffers, and each information group is divided into K LT packets of equal length; LT code coding unit, it carries out LT code coding to the K LT data packets in the coding buffer that the coding pointer currently points to obtains p coding packets, and sends the obtained p coding packets in sequence, and then points the coding pointer to The next encoding buffer, if the current encoding pointer points to the last encoding buffer, then point the encoding pointer to the first encoding buffer, wherein the number p of encoded packets is less than the number K of LT data packets; Judgment unit, which is used to judge whether the decoding feedback information from the decoding end is received during the LT code encoding process. If the decoding feedback information is received, it will not put into the encoding buffer and is located in the encoding queue The first group of information group at the head is put into the encoding buffer corresponding to the decoding feedback information, otherwise return to the LT code encoding unit to continue to perform LT encoding on the encoding buffer currently pointed to by the encoding pointer. 4. The multi-buffering non-constant-speed code transmission system according to claim 3, wherein the decoding end further comprises: A receiving unit, which is used to put the encoded packet into the corresponding decoding buffer according to the encoded buffer information obtained from the header information of the encoded packet when receiving the encoded packet; LT code decoding unit, when the total number of coded packets received in a certain decoding buffer is greater than K, it performs LT code decoding on the coded packets in the decoding buffer, if the decoding is successful, the decoded information group Put it at the end of the decoding queue and send decoding feedback information to the encoding end, otherwise the decoding buffer will continue to receive the p encoded packets sent by the corresponding encoding buffer, and perform LT code decoding on all the encoded packets it has received accumulatively , until the decoding is successful. 5. A multi-buffer non-constant-speed code transmission method for real-time services in dense communications, comprising: The encoding step is to set a plurality of encoding buffers, use the plurality of encoding buffers to sequentially perform LT code encoding on several information groups divided by the video stream to obtain multiple groups of multi-buffer LT codes, and send each group of multi-buffer LT codes in sequence , and update the corresponding information group in the encoding buffer in combination with the decoding feedback information; The transmission step is to transmit each group of multi-buffered LT codes in real time through the communication link; In the decoding step, a plurality of decoding buffers are set, and each decoding buffer is used to decode the LT codes of each group of multi-buffered LT codes accumulated therein to obtain the corresponding information group, and send decoding feedback information about the group of multi-buffered LT codes Feedback to the encoding end, and clear the corresponding decoding buffer, Wherein, there are at least two communication links, and when a problem occurs in one communication link, switch to another communication link for data transmission, or select another communication link to perform data transmission simultaneously with the communication link. 6. The multi-buffering non-constant-speed code transmission method according to claim 5, wherein, in the transmission step, the communication link communicates based on a non-link-oriented reliable transmission protocol, wherein the oriented The unlinked reliable transmission protocol is obtained based on the erasure channel composed of UDP packets and CRC checks and the encoding and decoding methods of multi-buffer LT codes. 7. The multi-buffering non-constant-speed code transmission method according to claim 5, wherein, in the encoding step, further comprising: Step 710, divide the video stream into several information groups of equal length, sort each information group in turn to form an encoding queue, and put the previously set number of information groups into each encoding buffer in turn, wherein the set The number of information groups is the same as the number of encoding buffers, and each information group is divided into K LT packets of equal length; Step 720: Perform LT code encoding on the K LT data packets in the encoding buffer currently pointed to by the encoding pointer to obtain p encoding packets, and send the obtained p encoding packets in sequence, and then point the encoding pointer to the next encoding Buffer, if the current encoding pointer points to the last encoding buffer, then point the encoding pointer to the first encoding buffer, wherein the number p of encoded packets is less than the number K of LT data packets; Step 730: During the encoding process of the LT code, it is judged whether the decoding feedback information from the decoding end is received. The group information group is put into the encoding buffer corresponding to the decoding feedback information, otherwise, return to step 720 and continue to perform LT code encoding on the encoding buffer currently pointed to by the encoding pointer. 8. The multi-buffering non-constant-speed code transmission method according to claim 7, wherein, in the decoding step, further comprising: Step 810, when receiving the encoded packet, put it into the corresponding decoding buffer according to the encoding buffer information obtained from the header information of the encoded packet; Step 820, when the total number of received encoded packets in a certain decoding buffer is greater than K, perform LT code decoding on the encoded packets in the decoding buffer, if the decoding is successful, put the decoded information group into the decoding The end of the queue and send decoding feedback information to the encoding end, otherwise the decoding buffer continues to receive p encoded packets sent by the corresponding encoding buffer, and performs LT code decoding on all the encoded packets it receives until decoding success. 9. according to the multi-buffer non-constant-speed code transmission method described in any one of claim 5-8, it is characterized in that, the transmission rate of described multi-buffer LT code is: ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; di</span>}}<span\; class="notranslate">\; )</span>}$ Among them, l is the total number of information groups, K is the number of LT data packets with the same length in each information group, P _m is the size of LT data packets, and s _i is the multi-buffer received before the ith information group is successfully decoded The number of groups of LT codes, p is the number of encoded packets generated by each information group, t _c is the transmission time corresponding to a group of multi-buffered LT codes corresponding to the transmission data link, t _di is the feedback information after decoding the i-th information group The time required to reach the decoder. 10. The multi-buffer non-constant-speed code transmission method according to claim 9, characterized in that, under the premise of satisfying max{t _di }<pmt _c -1, the transmission efficiency of the multi-buffer LT code is: $\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}$ Wherein, m is the number of encoding buffers, R is the actual transmission speed of the transmission data link, and E(s) is the expectation of the number of sets of multi-buffered LT codes received before successful decoding.

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