CN111314705B - Non-orthogonal multiple access image transmission system based on multiple description coding and application thereof - Google Patents
Non-orthogonal multiple access image transmission system based on multiple description coding and application thereof Download PDFInfo
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- H04N19/39—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability involving multiple description coding [MDC], i.e. with separate layers being structured as independently decodable descriptions of input picture data
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Abstract
A non-orthogonal multiple access image transmission system based on multiple description coding and application thereof, belonging to the technical field of image coding and transmission method, solving the technical problems of data transmission reliability and improving system capacity, the transmission system comprises the following steps: suppose there is one base station and user 1, user 2. At the transmitting end, the desired signals of user 1 and user 2 are first encoded via multiple descriptions to generate two descriptions, and then the base station allocates the total power to user 1
p, allocating total power to user 2
p, at the same time
And is
(ii) a The descriptions of the two users are then superimposed by superposition coding. The transmission enters a rayleigh fading channel and the base station sends superimposed signals to user 1 and user 2, respectively, through two orthogonal sub-channels. At the receiving end, the serial interference cancellation technology is used to demodulate the received signals of the user 1 and the user 2 respectively, and finally the expected image is reconstructed. The invention only obviously improves the robustness and the system capacity of the transmission system and also improves the fairness of users.
Description
Technical Field
The invention belongs to the technical field of image coding and transmission methods, and particularly relates to a non-orthogonal multiple access image transmission system based on multiple description coding and application thereof.
Background
With the coming of the mobile internet era, intelligent terminal devices such as mobile phones, tablets, robots and the like are popularized comprehensively. Nowadays, internet social contact also becomes one of indispensable communication modes, from early social software QQ, weChat, microblog to short video software such as trembler and fast hands. The appearance of internet social contact not only accelerates the speed of information exchange between people, but also reduces the cost of remote communication. However, as social ways are more diversified, images and videos become one of the most important carriers in the internet. Because the image has a faster reading speed compared with the text and the voice, and can carry a larger amount of information, the quality requirement of the image is higher and higher. The resolution of the image also reaches 8K from the original high definition, ultra high definition to the images with special requirements of 2K and 4K, however, the image resolution is improved and simultaneously a large amount of data is generated. The acquisition, processing, storage and transmission of these data become an important component of the communication transmission system.
Due to the problems of the channel itself, such as network heterogeneity, network congestion, transmission errors (packet loss and bit error), end-to-end delay, limited spectrum resources, etc., the transmission reliability of the data is seriously affected. Therefore, it becomes a key to guarantee the data communication quality to adopt proper transmission control measures. Therefore, the joint research of image coding technology and image transmission technology is also one of the current research hotspots.
With the rapid development of internet applications, the amount of network data also shows exponential growth. Therefore, 4G networks have been unable to cope with the mass data that has increased sharply, and thus fifth generation communication technology (5G) mobile communication technology has been in the process. The method can meet the requirement of simultaneous access of massive terminals, and has higher transmission rate and lower end-to-end time delay. At present, the internationally recognized 5G technology has the total global connection amount of 1000 hundred million, the data transmission rate can reach 10-20Gbps (10-20 times of the 4G peak rate), the user experience data rate reaches 1Gbps (100 times of the 4G user experience rate), the end-to-end time delay of the network is shortened to 1ms (one fifth of the 4G), and the spectrum efficiency of the system is improved by 5-10 times.
However, in the face of the demand of new generation wireless networks and the development of mobile communication technology, limited spectrum resources are becoming more and more scarce, and high frequency spectrum resources are not yet developed. Therefore, more advanced technologies must be found in 5G to solve these problems, and Non-Orthogonal Multiple Access (NOMA) is considered as the most promising candidate in 5G networks due to its excellent Spectral Efficiency (SE). For a wireless Network, the underlying physical connection is called a Radio Access technology (RAN), and is implemented by a Radio Access Network (RAN). The RAN provides core network connectivity for mobile terminals by using a channel radio access technology. Designing a suitable multiple access technology is one of the key factors for improving the system capacity.
The internet is developing width and dimension, and various multiplexing technologies and multi-path forwarding technologies are widely applied to exert the value of network bandwidth to the maximum extent. Decentralized internet enables one message to be shared by multiple users, i.e. when multiple users request the same image content from a base station, the base station can send the content simultaneously on the shared resource. Thus, limited spectrum resources are efficiently utilized while the transmit power of the base station is significantly reduced. As an efficient and highly fault-tolerant encoding technique, a Multiple Description Coding (MDC) technique not only can adapt to an error-prone network, but also can realize multi-path simultaneous transmission to ensure that a plurality of users share information. As a common error-resilient technique, MDC encodes a picture into multiple equally important descriptions, each sub-description being sent independently to the receiving end. At the receiving end, decoding and reconstruction can be performed independently even if only one description is received. At the same time, the effect of decoding the reconstruction is improved as the number of received descriptions increases. But since each description contains not only its own important information but also redundant information that helps to recover the other descriptions, a larger amount of data is generated during the encoding process.
Disclosure of Invention
In order to overcome the defects of the prior art and solve the technical problems of data transmission reliability and system capacity improvement, the invention provides a non-orthogonal multiple access image transmission system based on multiple description coding and application thereof.
The design concept of the invention is as follows: the non-orthogonal multiple access technology and the multiple description coding are combined, the high efficiency of the spectrum efficiency of the non-orthogonal multiple access technology and the advantage of higher system capacity are utilized, and the high fault tolerance of the multiple description coding is combined, so that a reliable and stable transmission network is constructed.
The invention is realized by the following technical scheme.
A multiple description coding based non-orthogonal multiple access image transmission system, comprising the steps of:
i, transmitting end signal processing: in a downlink multiple description coding non-orthogonal multiple access image transmission system, a transmitting end is assumed to comprise a base station and two users, wherein the two users are a user 1 far away from the base station and a user 2 close to the base station respectively, and the steps of signal processing of the transmitting end are as follows:
a. multiple description coding
a1. Respectively reading in image sequences x of user 1 and user 2 1 And x 2 ；
a2. Using an MDC encoder to the image sequence x obtained in step a1 1 And x 2 Encoding so that two image sequences x 1 And x 2 Correspondingly generating two descriptions x 1,k And x 2,k Where k denotes the kth sub-channel for transmission, k =1 or k =2;
a3. the description x obtained in step a2 1,k And x 2,k Respectively carrying out source coding to generate binary bit streams;
a4. performing digital modulation on the binary bit stream generated in the step a3 to modulate the binary bit stream into a corresponding symbol;
b. power distribution
According to the channel state information h corresponding to the user 1 and the user 2 1,k And h 2,k For step a4 power distribution of the modulated signal, h 1,k And, h 2,k Channel gains for user 1 and user 2, respectively, and h 1,k ＜h 2,k (ii) a Assuming total power p, user 1 allocates power α k p, user 2 allocated power of (1- α) k ) p and 0 < alpha k ＜1，α k ＞(1-α k ) Completing the power distribution of the user 1 and the user 2;
c. superposition coding: b, performing superposition coding on the signals subjected to power distribution in the step b to obtain a superposed signal X k As shown in equation (1):
d, OFDM modulation: performing OFDM modulation on the superposed signals obtained after the superposition coding in the step c to obtain OFDM transmission signals;
II, the OFDM transmission signal after the multi-description coding processing enters a Rayleigh fading channel and is transmitted to a receiving end;
III, decoding and reconstructing a signal at a receiving end: the process of decoding and reconstructing the signal at the receiving end is opposite to the process of processing the signal at the transmitting end, and the method comprises the following steps:
s1, a receiving end converts a received serial signal into a parallel receiving signal, wherein the parallel receiving signal is shown as a formula (2):
y 1 ＝h 1,k X K +n 1,k
y 2 ＝h 2,k X K +n 2,k (2)
in the formula, h 1,k And, h 2,k Channel gains for user 1 and user 2, n 1,k And n 2,k For channel noise, X k Is a superimposed signal;
s2, performing OFDM demodulation on the parallel receiving signals obtained in the step S1 to obtain OFDM demodulation signals;
s3, decoding the OFDM demodulation signal demodulated in the step S2 by using a serial interference elimination receiver;
s4, carrying out source decoding on the image decoded by the serial interference elimination receiver in the step S3;
and S5, reconstructing the signal decoded by the information source in the step S4, and completing the transmission of the non-orthogonal multiple access image based on the multiple description coding to obtain the expected image.
Further, system performance: in a non-orthogonal multiple access image transmission system based on multiple description coding, we mainly consider two transmission scenarios:
(1) the base station is not known about the instantaneous channel state information in said step b: the base station adopts fixed transmitting power and rate;
(2) the base station is known for the instantaneous channel state information in said step b: the base station adjusts the transmission rate according to the change of a wireless channel with fixed sending power;
on the basis, the interruption probability and the traversal rate of the non-orthogonal multiple access image transmission system based on the multi-description coding are further analyzed.
Further, when the base station is unknown for the instantaneous channel state information, the outage probability of the non-orthogonal multiple access image transmission system based on multiple description coding is as follows:
in the transmission system of non-orthogonal multiple access image based on multiple description coding, when user 1 can not successfully decode x 1,k Or user 2 cannot decode x 2,k When the image transmission system is interrupted; user 1 can successfully decode x 1,k The following conditions must be satisfied:
wherein R is 1 For a predefined target transmission rate for subscriber 1, <' >>
Receiving a sub-description x for user 1 1,k Actual receiving rate of; user 2 can successfully decode x 2,k The following two conditions must be satisfied: user 2 successfully decodes x 1,k While user 2 successfully decodes x 2,k I.e. is->
And->
Wherein R is 2 For a predefined target transmission rate for user 2, <' >>
Receiving a sub-description x for user 2 1,k Is actually received, is taken into account>
Receiving a sub-description x for user 2 2,k Actual receiving rate of;
the data transmission rate on sub-channel 1,
the data transmission rate on subchannel 1 for user 1;
the outage probabilities for user 1 and user 2 are shown in equation (3):
the total outage probability of the multi-description coding based non-orthogonal multiple access image transmission system is shown in formula (4):
P O ＝P(O 1 )×P(Ο 2 )。 (4)
further, when the base station is unknown for the instantaneous channel state information, the traversal rate of the multiple description coding based non-orthogonal multiple access image transmission system is as follows:
i. traversal rate of user 1: the transmission traversal rate from the base station to user 1 is shown in equation (5):
II, traversing rate of the user 2: the transmission traversal rate from the base station to user 2 is shown in equation (6):
traversal and rate: traversal and Rate
Is the traversal rate from the base station to user 1->
And a traversal rate from the base station to user 2 ≥>
Sum, traversal and rate->
As shown in equation (7):
a multiple description coding based non-orthogonal multiple access image transmission system is used for occasions requiring different channel bandwidths and occasions having scalability of image quality.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention adopts multi-description coding, power distribution algorithm, superposition coding and cross interference elimination technology at the same time, and not only obviously improves the robustness and system capacity of a transmission system, but also improves the fairness of users.
2. Compared with the traditional image transmission method, the invention has the following innovation points and advantages:
1) Multiple description coding encodes an image sequence into two descriptions of equal importance, any description received at the receiving end can reconstruct a coarse but acceptable image relative to the original image, and the quality of reconstruction is gradually improved as the received descriptions increase. Therefore, the problem that the quality is seriously reduced due to packet loss and time delay when the traditional information source coding is transmitted on an unreliable network is effectively solved;
2) At a sending end, different powers are distributed to users according to the channel state information of the users, so that the users with poor channels can obtain more powers, the users with good channels obtain less powers, the fairness of the users is improved by adjusting the power distribution ratio, and the two users can reconstruct images with good quality;
3) By using superposition coding, the frequency spectrum efficiency and the system throughput are effectively improved.
3. The invention is suitable for applications requiring different channel bandwidths and scalability to image quality.
Drawings
FIG. 1 is a system scenario block diagram of the present invention;
FIG. 2 is a diagram of a multiple description coding framework in the present invention;
FIG. 3 is a schematic diagram of a successive interference cancellation technique according to the present invention;
FIG. 4 is a block diagram of a digital transmission system of the present invention;
FIG. 5 is a graph of outage probability for User 1 and User 2 for different power allocation factors;
FIG. 6 is a graph of the traversal rates of USER-1 with respect to different power allocation factors;
FIG. 7 is a graph of the traversal rates of user 2 with respect to different power allocation factors;
FIG. 8 is a graph of PSNR performance at different compression ratios;
FIG. 9 is a graph comparing outage probability for the present invention with a conventional orthogonal multiple access scheme, a conventional non-orthogonal multiple access scheme, and a multiple description orthogonal multiple access scheme;
fig. 10 is a graph comparing traversal and rate of the present invention with a conventional orthogonal multiple access scheme, a conventional non-orthogonal multiple access scheme, and a multiple description orthogonal multiple access scheme.
Detailed Description
The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the examples follow conventional experimental conditions. In addition, it will be apparent to those skilled in the art that various modifications or improvements may be made in the material composition and the amount of the components in the embodiments without departing from the spirit and scope of the invention as defined in the appended claims.
A multiple description coding based non-orthogonal multiple access image transmission system as shown in fig. 1 to 4, comprising the steps of:
i, transmitting end signal processing: in a downlink multiple description coding non-orthogonal multiple access image transmission system, a transmitting end is assumed to comprise a base station and two users, wherein the two users are a user 1 far away from the base station and a user 2 close to the base station respectively, and the steps of signal processing of the transmitting end are as follows:
a. multiple description coding
a1. Respectively reading in image sequences x of user 1 and user 2 1 And x 2 ；
a2. Using an MDC encoder to the image sequence x obtained in step a1 1 And x 2 Encoding so that two image sequences x 1 And x 2 Correspondingly generating two descriptions x 1,k And x 2,k Where k denotes the kth sub-channel for transmission, k =1 or k =2;
a3. the description x obtained in step a2 1,k And x 2,k Respectively carrying out source coding to generate binary bit streams;
a4. carrying out digital modulation on the binary bit stream generated in the step a3 to modulate the binary bit stream into a corresponding symbol;
b. power distribution
According to the channel state information h corresponding to the user 1 and the user 2 1,k And h 2,k Performing power distribution on the signal modulated in the step a4, wherein h 1,k And, h 2,k Channel gains for user 1 and user 2, respectively, and h 1,k ＜h 2,k (ii) a Assuming total power p, user 1 allocates power α k p, user 2 allocated power of (1- α) k ) p, and 0 < alpha k ＜1，α k ＞(1-α k ) Completing the power distribution of the user 1 and the user 2;
c. superposition coding: will be provided withB, performing superposition coding on the signals subjected to power distribution in the step b to obtain a superposed signal X k As shown in equation (1):
and d, OFDM modulation: performing OFDM modulation on the superposed signal obtained after the superposition coding in the step c to obtain an OFDM transmission signal;
II, the OFDM transmission signal subjected to the multi-description coding processing enters a Rayleigh fading channel and is transmitted to a receiving end;
III, decoding and reconstructing a signal at a receiving end: the process of decoding and reconstructing the signal at the receiving end is opposite to the process of processing the signal at the transmitting end, and the method comprises the following steps:
s1, a receiving end converts a received serial signal into a parallel receiving signal, wherein the parallel receiving signal is shown as a formula (2):
y 1 ＝h 1,k X K +n 1,k
y 2 ＝h 2,k X K +n 2,k (2)
in the formula, h 1,k And, h 2,k Channel gains for user 1 and user 2, n 1,k And n 2,k For channel noise, X k Is a superimposed signal;
s2, carrying out OFDM demodulation on the parallel received signals obtained in the step S1 to obtain OFDM demodulated signals;
s3, decoding the OFDM demodulation signal demodulated in the step S2 by using a serial interference elimination receiver;
s4, carrying out source decoding on the image decoded by the serial interference elimination receiver in the step S3;
and S5, reconstructing the signal decoded by the information source in the step S4, and completing the transmission of the non-orthogonal multiple access image based on the multiple description coding to obtain the expected image.
Further, system performance: in a non-orthogonal multiple access image transmission system based on multiple description coding, we mainly consider two transmission scenarios:
(1) the base station is not known about the instantaneous channel state information in said step b: the base station adopts fixed transmitting power and rate;
(2) the base station is known for the instantaneous channel state information in said step b: the base station adjusts the transmission rate according to the change of a wireless channel with fixed sending power;
the interruption probability and the traversal rate of the non-orthogonal multiple access image transmission system based on the multiple description coding are further analyzed on the basis.
Further, when the base station is unknown for instantaneous channel state information, the outage probability of the non-orthogonal multiple access image transmission system based on multiple description coding is as follows:
in the transmission system of non-orthogonal multiple access image based on multiple description coding, when user 1 can not successfully decode x 1,k Or user 2 cannot decode x 2,k When the image transmission system is interrupted; user 1 can successfully decode x 1,k The following conditions must be satisfied:
wherein R is 1 For a predefined target transmission rate for subscriber 1, <' >>
Receiving a sub-description x for user 1 1,k Actual receiving rate of; (ii) a User 2 can successfully decode x 2,k The following two conditions must be satisfied: user 2 successfully decodes x 1,k While user 2 successfully decodes x 2,k I.e. is->
And->
Wherein R is 2 For a predefined target transmission rate for user 2>
Receiving a sub-description x for user 2 1,k Is actually received, is taken into account>
Receiving a sub-description x for user 2 2,k Actual receiving rate of;
the outage probabilities for user 1 and user 2 are shown in equation (3):
the total outage probability of the multi-description coding based non-orthogonal multiple access image transmission system is shown in formula (4):
P O ＝P(O 1 )×P(Ο 2 )。(4)
further, when the base station is unknown for the instantaneous channel state information, the traversal rate of the multiple description coding based non-orthogonal multiple access image transmission system is as follows:
i. traversal rate of user 1: the transmission traversal rate from the base station to user 1 is shown in equation (5):
II, traversing rate of the user 2: the transmission traversal rate from the base station to user 2 is shown in equation (6):
traversal and rate: traversal and rate
Is the traversal rate from the base station to user 1->
And a traversal rate from the base station to user 2 ≥>
Sum, traversal and rate->
As shown in equation (7):
a multiple description coding based non-orthogonal multiple access image transmission system is used for occasions requiring different channel bandwidths and occasions having scalability of image quality.
Fig. 5 is a graph of the outage probability for user 1 and user 2 for different power allocation factors, and it can be seen from the graph that the simulation result curve is completely fitted with the analysis result curve, and the outage probability for user 2 is higher than that for user 1.
Fig. 6 is a graph of the traversal rates of the user 1 with respect to different power allocation factors, and it can be seen from the graph that the simulation result curve is completely fitted with the analysis result curve, and the traversal rate of the user 1 is gradually increased as the power allocation ratio is increased.
Fig. 7 is a graph of the traversal rates of the user 2 with respect to different power allocation factors, and it can be seen from the graph that the simulation result curve is completely fitted with the analysis result curve, and the traversal rate of the user 2 is gradually reduced as the power allocation ratio is increased.
FIG. 8 is a graph of PSNR performance at different compression ratios, and it can be seen that as the compression ratio increases, the PSNR becomes smaller continuously, the PSNR value using the center decoder is higher than that using the side decoder, and the PSNR performance of user 2 is better than that of user 1.
Fig. 9 is a graph comparing the outage probability of the scheme of the present invention and the conventional orthogonal multiple access scheme, the conventional non-orthogonal multiple access scheme and the multiple description orthogonal multiple access scheme. As can be seen from the figure, the interrupt performance of the present invention is optimal, and the interrupt performance of the conventional orthogonal multiple access scheme is the worst.
Fig. 10 is a graph comparing traversal and rate of the scheme of the present invention with a conventional orthogonal multiple access scheme, a conventional non-orthogonal multiple access scheme, and a multiple description orthogonal multiple access scheme. It can be seen from the figure that the performance of the conventional non-orthogonal multiple access scheme is optimal, but the present invention is not clearly apart from its performance. Meanwhile, in the comparison graph of fig. 9 for the interrupt probability, it can be seen that the advantage of the scheme of the present invention in terms of the performance of the interrupt probability is more in advance of other schemes. It also shows that the present invention trades off the cost of weak traversal rate for better interrupt performance.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (5)
1. A multiple description coding based non-orthogonal multiple access image transmission system, comprising the steps of:
i, transmitting end signal processing: in a downlink multiple description coding non-orthogonal multiple access image transmission system, a transmitting end is assumed to comprise a base station and two users, wherein the two users are a user 1 far away from the base station and a user 2 close to the base station respectively, and the steps of signal processing of the transmitting end are as follows:
a. multi-description coding:
a1. respectively reading in image sequences x of user 1 and user 2 1 And x 2 ；
a2. Using MDC coder to obtain image sequence x in step a1 1 And x 2 Encoding such that two image sequences x 1 And x 2 Corresponding generation of two descriptions x 1,k And x 2,k Where k denotes the kth sub-channel for transmission, k =1 or k =2;
a3. the description x obtained in step a2 1,k And x 2,k Respectively carrying out source coding to generate binary bit streams;
a4. carrying out digital modulation on the binary bit stream generated in the step a3 to modulate the binary bit stream into a corresponding symbol;
b. power distribution:
according to the channel state information h corresponding to the user 1 and the user 2 1,k And h 2,k Performing power distribution on the signal modulated in the step a4, wherein h 1,k And, h 2,k Channel gains for user 1 and user 2, respectively, and h 1,k ＜h 2,k (ii) a Assuming total power p, user 1 allocates power α k p, user 2 allocated power of (1- α) k ) p, and 0 < alpha k ＜1，α k ＞(1-α k ) Completing the power distribution of the user 1 and the user 2;
c. superposition coding: b, performing superposition coding on the signals subjected to power distribution in the step b to obtain a superposed signal X k As shown in equation (1):
and d, OFDM modulation: performing OFDM modulation on the superposed signal obtained after the superposition coding in the step c to obtain an OFDM transmission signal;
II, the OFDM transmission signal after the multi-description coding processing enters a Rayleigh fading channel and is transmitted to a receiving end;
and III, decoding and reconstructing a signal at a receiving end: the process of decoding and reconstructing the signal at the receiving end is opposite to the process of processing the signal at the transmitting end, and the method comprises the following steps:
s1, a receiving end converts a received serial signal into a parallel receiving signal, and the parallel receiving signal is as shown in a formula (2):
y 1 ＝h 1,k X K +n 1,k ；
y 2 ＝h 2,k X K +n 2,k ； (2)
in the formula, h 1,k And, h 2,k Channel gains for user 1 and user 2, n 1,k And n 2,k For channel noise, X k Is a superimposed signal;
s2, carrying out OFDM demodulation on the parallel received signals obtained in the step S1 to obtain OFDM demodulated signals;
s3, decoding the OFDM demodulation signal demodulated in the step S2 by using a serial interference elimination receiver;
s4, carrying out source decoding on the image decoded by the serial interference elimination receiver in the step S3;
and S5, reconstructing the signal decoded by the information source in the step S4, and completing the transmission of the non-orthogonal multiple access image based on the multiple description coding to obtain the expected image.
2. The system according to claim 1, wherein the image transmission system comprises: the fixed transmission power and rate of the base station during the image transmission process are either of the following two cases:
(1) the base station is unknown for the instantaneous channel state information in said step b: the base station adopts fixed transmitting power and rate;
(2) the base station is known for the instantaneous channel state information in said step b: the base station adjusts the transmission rate according to the variation of the wireless channel of the fixed transmission power.
3. The system according to claim 2, wherein the image transmission system comprises: when the base station is unknown for instantaneous channel state information, the outage probability of a multiple description coding based non-orthogonal multiple access image transmission system is as follows:
in the transmission system of non-orthogonal multiple access image based on multiple description coding, when user 1 can not successfully decode x 1,k Or user 2 cannot decode x 2,k When the image transmission system is interrupted; user 1 can successfully decode x 1,k The following conditions must be satisfied:
wherein R is 1 For a predefined target transmission rate for subscriber 1, <' >>
Receiving a sub-description x for user 1 1,k Actual receiving rate of; user 2 can successfully decode x 2,k The following two conditions must be satisfied: user 2 successfully decodes x 1,k While user 2 successfully decodes x 2,k I.e. is->
And->
Wherein R is 2 For a predefined target transmission rate for user 2, <' >>
Receiving a sub-description x for user 2 1,k Is actually received, is taken into account>
Receiving a sub-description x for user 2 2,k Actual receiving rate of;
the outage probabilities for user 1 and user 2 are shown in equation (3):
the total outage probability of the multi-description coding based non-orthogonal multiple access image transmission system is shown in formula (4):
P O ＝P(O 1 )×P(Ο 2 )。 (4)
4. the system according to claim 2, wherein the image transmission system based on multiple description coding comprises: when the base station is unknown for the instantaneous channel state information, the traversal rate of the non-orthogonal multiple access image transmission system based on the multiple description coding is as follows:
i. traversal rate of user 1: the transmission traversal rate from the base station to user 1 is shown in equation (5):
II, the traversal rate of the user 2: the transmission traversal rate from the base station to user 2 is shown in equation (6):
traversal and rate: traversal and rate
Is the traversal rate from the base station to user 1->
And a traversal rate from the base station to user 2 ≥>
Sum, traversal and rate->
As shown in equation (7):
5. the system according to claim 1, wherein the image transmission system comprises: for applications requiring different channel bandwidths and for applications with scalability in picture quality.
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