Secure video transmission method and device based on extensible video coding

Abstract

The invention provides a secure video transmission method and device based on extensible video coding, and relates to the technical field of video transmission. The video transmission method comprises the following steps: according to a preset caching strategy, performing layered caching on a base layer file and a plurality of enhancement layer files of at least part of video files in a content server in a target macro base station and a target micro base station of a preset cellular network respectively; according to a video acquisition request sent by a target user, determining whether the at least part of video files contain a target video file or not; and if the at least part of the video files comprise the target video file, sending a base layer file of the target video file to the target user through the target macro base station, overlapping at least one enhancement layer file of the target video file in a non-orthogonal transmission mode through the target micro base station, and sending the overlapped at least one enhancement layer file to the target user. The video transmission efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of video transmission, and in particular, to a secure video transmission method and apparatus based on scalable video coding. Background Art

[0002] With the rapid development of wireless networks and the wide popularity of mobile terminal devices such as smart phones, tablet computers, and laptop computers, mobile data traffic will enter a new stage of rapid growth. Most of the consumption of mobile data traffic comes from video data traffic. The main driving force for the growth of video traffic is users' demand for social media push information and high-quality videos. Ensuring and improving the quality of service (QoS) of video received by users is crucial for increasing the revenue of operators, and thus has received great attention from the industry and academia.

[0003] However, in the vast amount of video services, a large number of duplicate video files are repeatedly transmitted through the backhaul link between the core network and the base station. For a period of time, 80% of the data traffic is composed of repeated requests for 20% of the popular video files. The repeated video data traffic brings huge pressure to the network. In addition, there may be illegal users with unauthenticated identities in the wireless network. Due to the openness of the wireless channel and the broadcast nature of wireless signals, there are security risks in the transmission process.

[0004] Therefore, how to ensure the efficient and secure delivery of the requested video files has become a challenging and necessary issue. Summary of the Invention

[0005] The purpose of the present invention is to provide a secure video transmission method and apparatus based on scalable video coding for the deficiencies in the above-mentioned prior art.

[0006] To achieve the above purpose, the technical solutions adopted in the embodiments of the present invention are as follows: In a first aspect, an embodiment of the present invention provides a secure video transmission method based on scalable video coding. The method includes: According to a preset caching policy, hierarchically cache the base layer files and multiple enhancement layer files of at least some video files in the content server in a target macro base station and a target micro base station of a preset cellular network respectively; Determine whether the target video file is included in the at least some video files according to a video acquisition request sent by a target user; If the target video file is included in the at least partial video files, send the base layer file of the target video file to the target user through the target macro base station, and superimpose at least one enhancement layer file of the target video file through the target micro base station using a non-orthogonal transmission method and then send it to the target user.

[0007] Optionally, the step of superimposing at least one enhancement layer file of the target video file through the target micro base station using a non-orthogonal transmission method and then sending it to the target user includes: Determine the number of layers of the enhancement layer file according to the video quality information in the video acquisition request; According to the number of layers of the enhancement layer file, superimpose the enhancement layer files of the corresponding number of layers of the target video file through the target micro base station using the non-orthogonal transmission method and then send it to the target user.

[0008] Optionally, the method further includes: If the target video file is not included in the at least partial video files, obtain the base layer file and multiple enhancement layer files of the target video file from the content server through the target macro base station and the target micro base station respectively based on the backhaul link; Send the base layer file of the target video file to the target user through the target macro base station using the allocated first orthogonal channel resource, and send at least one enhancement layer file of the target video file to the target user through the target micro base station using the allocated second orthogonal channel resource.

[0009] Optionally, the method further includes: Model the preset cellular network, where the preset cellular network includes: at least one macro base station, at least one micro base station, the target user, and at least one eavesdropper; Determine the first secure cache-aided data rate of the base layer file according to the first request probability, first cache probability, first successful transmission probability of sending the base layer file of the at least partial video files, secrecy outage probability, and first minimum cache-aided data rate of the base layer file of the at least partial video files; Determine the second secure cache-aided data rate of the enhancement layer file according to the second request probability, second cache probability, second successful transmission probability of sending the enhancement layer file of the at least partial video files, and second minimum cache-aided data rate of the enhancement layer file of the at least partial video files; Determine the target secure caching data rate of the preset cellular network according to the first secure caching assisted data rate and the second secure caching assisted data rate, where the target secure caching data rate is used to indicate the performance of caching and transmitting video files when there is an eavesdropper in the preset cellular network.

[0010] Optionally, the method further includes: Calculate a first received signal-to-interference ratio of the target user receiving the base layer file according to the small-scale channel fading and distance between the target user and the target macro base station, and the small-scale channel fading and distance between the target user and other macro base stations; Determine a first probability density function of the distance between the target macro base station and the target user according to the density of the at least one macro base station; Calculate a first successful transmission probability of sending each base layer file according to the first received signal-to-interference ratio and the first probability density function.

[0011] Optionally, the method further includes: Calculate a second received signal-to-interference ratio of the target user receiving the enhancement layer file according to the small-scale channel fading and distance between the target user and the target micro base station, and the small-scale channel fading and distance between the target user and other micro base stations; Determine a second probability density function of the distance between the target micro base station and the target user according to the density of the at least one micro base station; Calculate a second successful transmission probability of sending each enhancement layer file according to the second received signal-to-interference ratio and the second probability density function.

[0012] Optionally, the method further includes: Determine a third received signal-to-interference ratio of each eavesdropper according to the channel fading and distance between each eavesdropper and the macro base station being eavesdropped, and the channel fading and distance between each eavesdropper and the non-eavesdropped macro base stations; Calculate the secrecy outage probability according to the density of the at least one eavesdropper, the density of the at least one macro base station, and the third received signal-to-interference ratio.

[0013] Optionally, the method further includes: Calculate the first minimum caching assisted data rate according to the transmission bandwidth of the target macro base station and the minimum reception threshold of the base layer file.

[0014] Optionally, the method further includes: Calculate the second minimum caching assisted data rate according to the transmission bandwidth of the target micro base station and the minimum reception threshold of the enhancement layer file.

[0015] In a second aspect, an embodiment of the present invention provides a secure video transmission device based on scalable video coding. The device includes: A caching module, configured to perform hierarchical caching of the base layer file and multiple enhancement layer files of at least part of the video files in the content server in a target macro base station and a target micro base station of a preset cellular network respectively according to a preset caching policy; A determination module, configured to determine whether a target video file is included in the at least part of the video files according to a video acquisition request sent by a target user; A sending module, configured to, if the target video file is included in the at least part of the video files, send the base layer file of the target video file to the target user through the target macro base station, and perform superposition on at least one enhancement layer file of the target video file through the target micro base station by using a non-orthogonal transmission method and then send it to the target user.

[0016] Optionally, the sending module is further configured to determine the number of layers of the enhancement layer files according to the video quality information in the video acquisition request; and according to the number of layers of the enhancement layer files, perform superposition on the enhancement layer files corresponding to the number of layers of the target video file through the target micro base station by using the non-orthogonal transmission method and then send it to the target user.

[0017] Optionally, the device further includes: An acquisition module, configured to, if the target video file is not included in the at least part of the video files, acquire the base layer file and multiple enhancement layer files of the target video file from the content server through the target macro base station and the target micro base station respectively based on a backhaul link; The sending module is further configured to send the base layer file of the target video file to the target user through the target macro base station by using allocated first orthogonal channel resources, and send at least one enhancement layer file of the target video file to the target user through the target micro base station by using allocated second orthogonal channel resources.

[0018] Optionally, the device further includes: A modeling module, configured to model the preset cellular network, where the preset cellular network includes: at least one macro base station, at least one micro base station, the target user, and at least one eavesdropper; A calculation module, configured to determine a first secure caching auxiliary data rate of the base layer file according to a first request probability, a first caching probability, a first successful transmission probability of sending the base layer file of the at least part of the video files, a secrecy outage probability, and a first minimum caching auxiliary data rate of the base layer file of the at least part of the video files; The computing module is further configured to determine a second secure caching auxiliary data rate of the enhancement layer file according to a second request probability, a second caching probability, a second successful transmission probability of transmitting the enhancement layer file of the at least partial video file, and a second minimum caching auxiliary data rate of the enhancement layer file of the at least partial video file; The computing module is further configured to determine a target secure caching data rate of the preset cellular network according to the first secure caching auxiliary data rate and the second secure caching auxiliary data rate, where the target secure caching data rate is used to indicate the performance of caching and transmitting a video file when there is an eavesdropper in the preset cellular network.

[0019] Optionally, the computing module is further configured to calculate a first received signal-to-interference ratio of the target user receiving the base layer file according to the small-scale channel and distance between the target user and the target macro base station, and the small-scale channel fading and distance between the target user and other macro base stations; determine a first probability density function of the distance between the target macro base station and the target user according to the density of the at least one macro base station; and calculate a first successful transmission probability of transmitting each base layer file according to the first received signal-to-interference ratio and the first probability density function.

[0020] Optionally, the computing module is further configured to calculate a second received signal-to-interference ratio of the target user receiving the enhancement layer file according to the small-scale channel fading and distance between the target user and the target micro base station, and the small-scale channel fading and distance between the target user and other micro base stations; determine a second probability density function of the distance between the target micro base station and the target user according to the density of the at least one micro base station; and calculate a second successful transmission probability of transmitting each enhancement layer file according to the second received signal-to-interference ratio and the second probability density function.

[0021] Optionally, the computing module is further configured to determine a third received signal-to-interference ratio of each eavesdropper according to the channel fading and distance between each eavesdropper and the macro base station being eavesdropped, and the channel fading and distance between each eavesdropper and the macro base stations not being eavesdropped; and calculate the secrecy outage probability according to the density of the at least one eavesdropper, the density of the at least one macro base station, and the third received signal-to-interference ratio.

[0022] Optionally, the computing module is further configured to calculate the first minimum caching auxiliary data rate according to the transmission bandwidth of the target macro base station and the lowest reception threshold of the base layer file.

[0023] Optionally, the computing module is further configured to calculate the second minimum caching auxiliary data rate according to the transmission bandwidth of the target micro base station and the lowest reception threshold of the enhancement layer file.

[0024] The beneficial effects of the present invention are as follows: The secure video transmission method and apparatus based on scalable video coding provided in this application use scalable video coding technology to perform hierarchical caching on video files, and send the base layer file and the enhancement layer file to users through a macro base station and a micro base station respectively, effectively improving the video transmission efficiency. Further, the enhancement layer file is divided into multiple layers, and the enhancement layer files with different numbers of layers can provide different video qualities to meet the diverse viewing needs of users. At the same time, it can flexibly adapt to the dynamically changing network state, improve the user content experience quality, and alleviate the network congestion problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a schematic diagram of the application scenario of the embodiment of the present invention; Figure 2 It is the flow of the secure video transmission method provided by the embodiment of the present invention Figure 1 ; Figure 3 It is the flow of the secure video transmission method provided by the embodiment of the present invention Figure 2 ; Figure 4 It is the flow of the secure video transmission method provided by the embodiment of the present invention Figure 3 ; Figure 5 It is the flow of the secure video transmission method provided by the embodiment of the present invention Figure 4 ; Figure 6 It is a simulation diagram of the first successful transmission probability of the base layer file provided by the embodiment of this application; FIG. 7(a) is a simulation diagram of the second successful transmission probability of the first layer enhancement layer file provided by the embodiment of this application; FIG. 7(b) is a simulation diagram of the second successful transmission probability of the second layer enhancement layer file provided by the embodiment of this application; Figure 8 It is a simulation diagram of the secrecy outage probability of the base layer file provided by the embodiment of this application; Figure 9 It is a simulation diagram of the target secrecy caching data rate provided by the embodiment of this application; Figure 10Schematic diagram of the secure video transmission device provided by the embodiments of the present application. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0029] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, rather than physical diagrams, and should not be construed as a limitation to the present invention; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0030] To better understand the solution of the present invention, the application scenarios of the secure video transmission method of the present invention will be introduced below.

[0031] Figure 1 Schematic diagram of the application scenario of the embodiments of the present invention. As Figure 1 shown, in a cellular network that supports caching and has a risk of eavesdropping, there are a macro base station (Macro-cell Base Station, MBS), a small cell base station (Small-cell Base Station, SBS), legitimate users, and a passive eavesdropper (Eavesdropper, Eve).

[0032] Based on the above application scenarios, the specific implementation manners of the secure video transmission method provided by the present invention will be described below in conjunction with the embodiments.

[0033] Figure 2 Flow of the secure video transmission method provided by the embodiments of the present invention Figure 1 As Figure 2 shown, the secure video transmission method may include: Step 101: According to the preset caching policy, hierarchically cache the base layer files and multiple enhancement layer files of at least some of the video files in the content server in the target macro base station and the target micro base station of the preset cellular network respectively.

[0034] Specifically, the macro base station and the micro base station of the preset cellular network communicate with the content server respectively to obtain video files from the content server. Among them, there are multiple video files stored in the content server. According to the number of times legal users request each video file within the coverage of the preset cellular network, the popularity of each video file can be determined.

[0035] The content server uses Scalable Video Coding (SVC) technology to encode each video file into L layers, including one Base Layer (BL) file and L - 1 Enhancement Layer (EL) files respectively.

[0036] According to the preset caching policy and the caching capacities of the macro base station and the micro base station, cache at least some of the video files from multiple video files. Among them, if the preset caching policy is equal - probability caching, randomly cache multiple video files until there is no remaining caching capacity in each base station. The caching probability of equal - probability caching is the caching capacity divided by the total size of the video files. For example, if the total caching capacity of the macro base station and the micro base station can hold 10 layer files, each video file contains 3 layers, and there are 10 video files in the content server, with a total of 30 layer files, then only 10 layer files can be cached from the content server, and the caching probability is about 33%. During the process of caching video files, it is necessary to cache the base layer files and the enhancement layer files simultaneously.

[0037] If the preset caching policy is caching by popularity, sort the multiple video files according to their popularity, and cache each video file in order from high to low. After all L layers of each video file are cached, then cache the next video file until there is no remaining caching capacity. Among them, the caching probability of the cached video file is 1, and the caching probability of the uncached video file is 0.

[0038] During the caching process, cache the BL layer files in each macro base station of the preset cellular network, and cache the EL layer files in each micro base station of the preset cellular network.

[0039] Step 102: According to the video acquisition request sent by the target user, determine whether the target video file is included in at least some of the video files.

[0040] Specifically, the target user sends a video acquisition request to a preset cellular network. The video acquisition request includes the file identifier of the target video file. According to the location of the target user, the radius of the target user is determined. The nearest micro base station within the range is determined as the target micro base station, and the nearest macro base station is determined as the target macro base station. It is determined whether there is a base layer file of the target video file in the target macro base station, and it is determined whether there is an enhancement layer file of the target video file in the target micro base station.

[0041] Step 103: If at least some of the video files contain the target video file, the base layer file of the target video file is sent to the target user through the target macro base station, and at least one enhancement layer file of the target video file is superimposed by the target micro base station using non-orthogonal transmission and then sent to the target user.

[0042] Specifically, if there is a base layer file of the target video file in the target macro base station, the base layer file of the target video file is sent to the target user through the target macro base station. If there is an enhancement layer file of the target video file in the target micro base station, the enhancement layer file of the target video file is sent to the target user through the target micro base station.

[0043] Among them, the target micro base station uses non-orthogonal transmission to send the enhancement layer file of the target video file to the target user. Non-orthogonal transmission is to superimpose the enhancement layer files of the target video file, and the target user uses decoding technology to decode the enhancement layer file of the target video file from the superimposed signal.

[0044] The secure video transmission method based on scalable video coding provided in the above embodiment uses scalable video coding technology to cache video files in layers, and sends the base layer file and the enhancement layer file to the user through the macro base station and the micro base station respectively, improving the video transmission efficiency.

[0045] In some possible implementation manners, Figure 3 is the flow of the secure video transmission method provided in the embodiment of the present invention Figure 2 , as Figure 3 shown, the process of step 103 of superimposing at least one enhancement layer file of the target video file by the target micro base station using non-orthogonal transmission and then sending it to the target user may include: Step 201: Determine the number of layers of the enhancement layer file according to the video quality information in the video acquisition request.

[0046] Step 202: According to the number of layers of the enhancement layer file, the enhancement layer files corresponding to the number of layers of the target video file are superimposed by the target micro base station using non-orthogonal transmission and then sent to the target user.

[0047] Specifically, the base layer file contains the basic and necessary information of the video file, and the enhancement layer file contains enhancement information and improves the received video quality. According to the number of layers of the enhancement layer file, the video quality level is divided, and the corresponding relationship between the video quality and the number of layers of the enhancement layer file is determined. It is determined that the more the number of layers of the enhancement layer file, the higher the video quality level, and the fewer the number of layers of the enhancement layer file, the lower the video quality level.

[0048] The video quality information in the video acquisition request sent by the target user to the preset cellular network is the requested video quality level. According to the video quality level, the number of layers of the enhancement layer file is determined, and the target micro base station sends the enhancement layer file with the corresponding number of layers to the target user.

[0049] Furthermore, the target micro base station superimposes the enhancement layer files with the corresponding number of layers and sends them to the target user. The target user decodes the enhancement layer files with the corresponding number of layers from the superimposed signal, combines them with the base layer file, and displays the content of the target video file on the terminal device of the target user.

[0050] In some embodiments, the video quality level can be the video quality level selected by the target user through the video software program of the terminal device, or the video quality level automatically matched according to the network state of the terminal device. This embodiment does not limit this.

[0051] The secure video transmission method based on scalable video coding provided by the above embodiment divides the enhancement layer file into multiple layers. Different numbers of layers of the enhancement layer file can provide different video qualities to meet the diverse viewing needs of users. At the same time, it can flexibly adapt to the dynamically changing network state, improve the user content experience quality, and alleviate the network congestion problem.

[0052] In some possible implementation manners, Figure 4 is the flow of the secure video transmission method provided by the embodiment of the present invention Figure 3 , as Figure 4 shown, this secure video transmission method may further include: Step 301: If at least part of the video files do not contain the target video file, the base layer file and multiple enhancement layer files of the target video file are respectively obtained from the content server based on the backhaul link through the target macro base station and the target micro base station.

[0053] Specifically, if the base layer file of the target video file is not included in the target macro base station and the enhancement layer file of the target video file is not included in the target micro base station, it is determined that the target video file is not cached and needs to be obtained from the content server.

[0054] Among them, the target macro base station sends a request for obtaining the base layer file of the target video file to the content server through the backhaul link. The content server sends the base layer file of the target video file to the target macro base station through the backhaul link. The target micro base station sends a request for obtaining the enhancement layer file of the target video file to the content server through the backhaul link. The content server sends the enhancement layer file of the target video file to the target micro base station through the backhaul link. The number of layers of the obtained enhancement layer file can be determined according to the method in step 201 above.

[0055] Step 302: The target macro base station uses the allocated first orthogonal channel resource to send the base layer file of the target video file to the target user, and the target micro base station uses the allocated second orthogonal channel resource to send at least one enhancement layer file of the target video file to the target user.

[0056] Specifically, in order to avoid decoding interference caused by the target macro base station and the target micro base station separately sending the base layer file and the enhancement layer file to the target user, it is necessary to allocate orthogonal channel resources for the target macro base station and the target micro base station. A part of the orthogonal channel resources allocated to the target macro base station is the first orthogonal channel resource, and another part of the orthogonal signal resources allocated to the target micro base station is the second orthogonal channel resource. The target macro base station sends the base layer file of the target video file to the target user based on the first orthogonal channel resource, and the target micro base station sends the enhancement layer file of the target video file to the target user based on the second orthogonal channel resource.

[0057] The secure video transmission method based on scalable video coding provided in the above embodiment, in the case where the target video file is not cached, obtains the base layer file and the enhancement layer file of the target video file from the content server through the backhaul link, and respectively sends the base layer file and the enhancement layer file of the target video file to the user based on the allocated orthogonal channel resources, avoiding decoding interference between the base layer file and the enhancement layer file and ensuring correct decoding.

[0058] In some possible implementation manners, Figure 5 is the flowchart of the secure video transmission method provided by the embodiment of the present invention Figure 4 as Figure 5 shown, this method may further include: Step 401: Model a preset cellular network, where the preset cellular network includes: at least one macro base station, at least one micro base station, a target user, and at least one eavesdropper.

[0059] Step 402: Determine the first secure caching auxiliary data rate of the base layer file according to the first request probability, the first caching probability, the first successful transmission probability of sending at least part of the base layer file of the video file, the secrecy outage probability, and the first minimum caching auxiliary data rate of the base layer file.

[0060] Step 403: Determine the second secure caching auxiliary data rate of the enhancement layer file according to the second request probability, the second caching probability, the second successful transmission probability of sending the enhancement layer file of at least part of the video file, and the second minimum caching auxiliary data rate.

[0061] Step 404: Determine the target secure caching data rate of the preset cellular network according to the first secure caching auxiliary data rate and the second secure caching auxiliary data rate. The target secure caching data rate is used to indicate the performance of caching and transmitting video files when there is an eavesdropper in the preset cellular network.

[0062] Specifically, in order to evaluate the performance of video transmission using the secure video transmission method provided by the present invention for the preset cellular network, the preset cellular network is modeled. Among them, the positions of the MBS, SBS, and Eve are respectively modeled as independent and identically distributed Poisson point processes , , , and their density parameters are respectively , , .

[0063] Among the legitimate users with video viewing requirements, randomly select one as the target user, denoted as . The SBS with caching ability can send the requested content to the legitimate users within its coverage radius . Assume that each node in the network is equipped with a single antenna. The target MBS and the target SBS that provide services in the present invention are respectively denoted as and .

[0064] The number of at least part of the video files is F. The first request probability is the probability that the base layer file of the f th video file is requested by the user to obtain. The second request probability is the probability that each layer of the enhancement layer file of the f th video file is requested by the user to obtain. The first request probability f and the second request probability can be calculated according to the popularity of the th video file.

[0065] Exemplarily, the formulas for calculating the first request probability and the second request probability can be expressed as: Among them, p(f) is the fThe popularity of a video file, according to the Mandelbrot-Zipf law, , where is the skewness parameter, which is used to reflect the concentration degree of requests. The larger q is, the flatter factor, q the larger

[0066] The first caching probability is the probability that the base layer file of the f-th video file is cached by the target macro base station, and the second caching probability is the probability that each enhancement layer file of the f-th video file is cached by the target micro base station, and the caching probability can be determined according to the foregoing caching policy.

[0067] The first successful transmission probability is used to represent the probability that the macro base station successfully transmits the base layer file of the video file requested by the user. In this solution, the first successful transmission probability of the target macro base station transmitting the base layer file of the target video file to the target user represents the probability that each macro base station successfully transmits the base layer file of the video file requested by its served user.

[0068] The second successful transmission probability is used to represent the probability that the micro base station successfully transmits the enhancement layer file of the video file requested by the user. In this solution, the first successful transmission probability of the target micro base station transmitting the enhancement layer file of the target video file to the target user represents the probability that each micro base station successfully transmits the enhancement layer file of the video file requested by its served user.

[0069] The secrecy outage probability is the probability of being eavesdropped by an eavesdropper during the process of the macro base station sending the base layer file of the video file to the user.

[0070] The first minimum cache-aided data rate is used to represent the minimum data rate at which the macro base station sends the base layer file based on the allocated system bandwidth, and the second minimum cache-aided data rate is used to represent the minimum data rate at which the micro base station sends the enhancement layer file based on the allocated system bandwidth.

[0071] The calculation formula of the target secrecy cache-aided data rate (SCADR) can be expressed as: In some embodiments, the process of calculating the first successful transmission probability may include: Calculate the first received signal-to-interference ratio (SIR) of the target user for receiving the base layer file based on the small-scale channel fading and distance between the target user and the target macro base station (MBS), and the small-scale channel fading and distance between the target user and other macro base stations. Determine the first probability density function of the distance between the target MBS and the target user according to the density of at least one macro base station. Calculate the first successful transmission probability of each base layer file based on the first received SIR and the first probability density function.

[0072] Specifically, the calculation formula for the first received SIR can be expressed as: where and are the small-scale channel fadings between the target user and the target MBS, i.e., and other non-serving MBSs, respectively, following a complex Gaussian distribution with a mean of 0 and a variance of 1, denoted as ; is the distance between and the target user ; is the distance between the non-serving MBS and the target user ;

[0073] Determine the first probability density function of the distance between the target MBS, i.e., r and its served user as follows: where is the density of the MBS.

[0074] Determine the successful transmission probability of the BL as follows: where Pr represents probability calculation, is the minimum received threshold to ensure correct decoding of the signal transmitted by the MBS.

[0075] The first successful transmission probability in this case obtained through the above formula is: where ; ; x is the integration variable.

[0076] Exemplarily, Figure 6 is the simulation diagram of the first successful transmission probability of the base layer file provided by the embodiment of the present application, as shown in Figure 6As shown, more than 50,000 Monte Carlo simulation experiments are conducted for each QoS point. The simulation results show that the performance gap between the analysis results and the Monte Carlo simulation results can be ignored. It can be seen that obviously, the lower the quality of service (QoS) requirement, the higher the first successful transmission probability.

[0077] In some embodiments, the process of calculating the second successful transmission probability may include: Calculating the second received signal-to-interference ratio (SIR) of the target user receiving the enhancement layer file according to the small-scale channel fading and distance between the target user and the target micro base station, and the small-scale channel fading and distance between the target user and other micro base stations; determining the second probability density function of the distance between the target micro base station and the target user according to the density of at least one micro base station; and calculating the second successful transmission probability of sending each enhancement layer file according to the second received SIR and the second probability density function.

[0078] Specifically, the second received SIR at the user when transmitting the th enhancement layer file is determined by the following formula: where the small-scale channel fadings from the target SBS and other non-serving SBSs are denoted as and , and they follow ; is the distance between the target SBS and the target user ; is the distance between a non-serving SBS and the target user ; is the path loss coefficient.

[0079] The second probability density function of the distance r between the nearest SBS and the user it serves is determined by the following formula: where is the density of the SBS.

[0080] The successful transmission probability of the th enhancement layer file is determined by the following formula: where is the minimum received threshold to ensure that the signal transmitted by the SBS can be correctly decoded.

[0081] The successful transmission probability of the th EL is obtained through the above formula: Among them, , , is the power transfer factor. Since the enhanced layer files need to be transmitted in superposition in the power domain, a power allocation factor is applied to each enhanced layer file.

[0082] Exemplarily, FIG. 7(a) is a simulation diagram of the second successful transmission probability of the first-layer enhanced layer file provided by the embodiment of the present application, and FIG. 7(b) is a simulation diagram of the second successful transmission probability of the second-layer enhanced layer file provided by the embodiment of the present application. As shown in FIGS. 7(a) and 7(b), the number of layers of the enhanced layer file is 2, and the correctness of the successful transmission probabilities of EL1 and EL2 is verified respectively. More than 50,000 Monte Carlo simulation experiments are carried out for each QoS point. The simulation results show that the performance gap between the analysis results and the Monte Carlo simulation results can be ignored. It can be seen that obviously, the lower the quality of service QoS requirement is, the higher the second successful transmission probability is.

[0083] In some embodiments, the process of calculating the secrecy outage probability may include: Determine the third received signal-to-interference ratio of each eavesdropper according to the channel fading and distance between each eavesdropper and the eavesdropped macro base station, and the channel fading and distance between each eavesdropper and the non-eavesdropped macro base station; calculate the secrecy outage probability according to the density of at least one eavesdropper, the density of at least one macro base station, and the third received signal-to-interference ratio.

[0084] Specifically, the third received signal-to-interference ratio of the th Eve in the network is determined according to the following formula: Among them, and are the channel fadings between the th Eve and the eavesdropped MBS and other non-eavesdropped MBSs respectively, and they follow ; is the distance between the eavesdropped MBS and the th Eve; is the distance between the non-eavesdropped MBS and the th Eve; is the path loss coefficient.

[0085] The secrecy outage probability of BL is determined according to the following formula: Among them, is the predetermined threshold for the Eve to receive the signal.

[0086] By using random geometry tools, the secrecy outage probability when transmitting the base layer file is obtained: Among them, is the density of Eve, is the integration result when the lower limit of the integration is 0.

[0087] Exemplarily, Figure 8 is the simulation diagram of the secrecy outage probability of the base layer file provided by the embodiment of the present application. As shown in Figure 8 , more than 50,000 Monte Carlo simulation experiments are carried out for each QoS point. The simulation results show that the performance gap between the analysis result and the Monte Carlo simulation result can be ignored. It can be seen that obviously, the lower the quality of service (QoS) requirement, the higher the secrecy outage probability.

[0088] In some embodiments, the process of calculating the first minimum caching-aided data rate may include: Calculating the first minimum caching-aided data rate according to the transmission bandwidth of the target macro base station and the minimum reception threshold of the base layer file.

[0089] Specifically, the first minimum caching-aided data rate , is the system bandwidth allocated for MBS transmission.

[0090] In some embodiments, the process of calculating the second minimum caching-aided data rate may include: Calculating the second minimum caching-aided data rate according to the transmission bandwidth of the target micro base station and the minimum reception threshold of the enhancement layer file.

[0091] Specifically, the second minimum caching-aided data rate , represents the system bandwidth allocated for SBS transmission.

[0092] Based on the above formula, the calculation formula of the target secrecy caching-aided data rate (SCADR) can be expressed as: Exemplarily, Figure 9 is the simulation diagram of the target secrecy caching-aided data rate provided by the embodiment of the present application. As shown in Figure 9 , by comparing the two schemes of equal-probability caching and popularity-based caching, it can be seen that the SCADR of popularity-based caching is better than that of equal-probability caching because equal-probability caching ignores the content popularity and viewing quality preferences of different videos and layers.

[0093] Based on the above method embodiments, an embodiment of the present invention provides a secure video transmission device based on scalable video coding. Figure 10 It is a schematic diagram of the secure video transmission device provided by the embodiment of the present application. As Figure 10 shown, the device may include: A caching module, configured to hierarchically cache the base layer file and multiple enhancement layer files of at least part of the video files in the content server in the target macro base station and the target micro base station of the preset cellular network respectively according to a preset caching policy; A determining module, configured to determine whether the target video file is included in at least part of the video files according to the video acquisition request sent by the target user; A sending module, configured to, if the target video file is included in at least part of the video files, send the base layer file of the target video file to the target user through the target macro base station, and superimpose at least one enhancement layer file of the target video file through the target micro base station by using a non-orthogonal transmission method and then send it to the target user.

[0094] Optionally, the sending module is further configured to determine the number of layers of the enhancement layer files according to the video quality information in the video acquisition request; according to the number of layers of the enhancement layer files, superimpose the corresponding number of enhancement layer files of the target video file through the target micro base station by using a non-orthogonal transmission method and then send it to the target user.

[0095] Optionally, the device further includes: An acquisition module, configured to, if the target video file is not included in at least part of the video files, acquire the base layer file and multiple enhancement layer files of the target video file from the content server through the target macro base station and the target micro base station respectively based on the backhaul link; The sending module is further configured to send the base layer file of the target video file to the target user through the allocated first orthogonal channel resource by the target macro base station, and send at least one enhancement layer file of the target video file to the target user through the allocated second orthogonal channel resource by the target micro base station.

[0096] Optionally, the device further includes: A modeling module, configured to model the preset cellular network, where the preset cellular network includes: at least one macro base station, at least one micro base station, a target user, and at least one eavesdropper; A calculation module, configured to determine the first secrecy caching auxiliary data rate of the base layer file according to the first request probability, the first caching probability, the first successful transmission probability of sending the base layer file of at least part of the video files, the secrecy outage probability, and the first minimum caching auxiliary data rate of the base layer file of at least part of the video files. The calculation module is further configured to determine the second secure caching auxiliary data rate of the enhancement layer file according to the second request probability, the second caching probability, the second successful transmission probability of sending the enhancement layer file of at least part of the video file, and the second minimum caching auxiliary data rate. The calculation module is further configured to determine the target secure caching data rate of the preset cellular network according to the first secure caching auxiliary data rate and the second secure caching auxiliary data rate. The target secure caching data rate is used to indicate the performance of caching and transmitting video files in the case that there is an eavesdropper in the preset cellular network.

[0097] Optionally, the calculation module is further configured to calculate the first received signal-to-interference ratio of the target user receiving the base layer file according to the small-scale channel fading and distance between the target user and the target macro base station, and the small-scale channel fading and distance between the target user and other macro base stations; determine the first probability density function of the distance between the target macro base station and the target user according to the density of at least one macro base station; calculate the first successful transmission probability of sending each base layer file according to the first received signal-to-interference ratio and the first probability density function.

[0098] Optionally, the calculation module is further configured to calculate the second received signal-to-interference ratio of the target user receiving the enhancement layer file according to the small-scale channel fading and distance between the target user and the target micro base station, and the small-scale channel fading and distance between the target user and other micro base stations; determine the second probability density function of the distance between the target micro base station and the target user according to the density of at least one micro base station; calculate the second successful transmission probability of sending each enhancement layer file according to the second received signal-to-interference ratio and the second probability density function.

[0099] Optionally, the calculation module is further configured to determine the third received signal-to-interference ratio of each eavesdropper according to the channel fading and distance between each eavesdropper and the macro base station being eavesdropped, and the channel fading and distance between each eavesdropper and the macro base stations not being eavesdropped; calculate the secrecy outage probability according to the density of at least one eavesdropper, the density of at least one macro base station, and the third received signal-to-interference ratio.

[0100] Optionally, the calculation module is further configured to calculate the first minimum caching auxiliary data rate according to the transmission bandwidth of the target macro base station and the minimum reception threshold of the base layer file.

[0101] Optionally, the calculation module is further configured to calculate the second minimum caching auxiliary data rate according to the transmission bandwidth of the target micro base station and the minimum reception threshold of the enhancement layer file.

[0102] The above device is used to execute the method provided in the foregoing embodiment, and its implementation principle and technical effects are similar, and will not be described in detail here.

[0103] The above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more application specific integrated circuits (ASICs), or, one or more microprocessors, or, one or more field programmable gate arrays (FPGAs), etc. Again, when a certain module above is implemented in the form of a processing element scheduler code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processors that can call program code. Again, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0104] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A secure video transmission method based on scalable video coding, characterized in that, The method includes: According to a preset caching policy, hierarchically cache the base layer files and multiple enhancement layer files of at least some video files in the content server in the target macro base station and the target micro base station of the preset cellular network respectively; According to a video acquisition request sent by a target user, determine whether the target video file is included in the at least some video files; If the target video file is included in the at least some video files, send the base layer file of the target video file to the target user through the target macro base station, and send at least one enhancement layer file of the target video file to the target user after superimposing through the target micro base station by using a non-orthogonal transmission method.

2. The method according to claim 1, wherein The sending at least one enhancement layer file of the target video file to the target user after superimposing through the target micro base station by using a non-orthogonal transmission method includes: Determine the number of layers of the enhancement layer file according to the video quality information in the video acquisition request; According to the number of layers of the enhancement layer file, send at least one enhancement layer file corresponding to the target video file to the target user after superimposing through the target micro base station by using the non-orthogonal transmission method.

3. The method according to claim 1, characterized in that The method further includes: If the target video file is not included in the at least some video files, obtain the base layer file and multiple enhancement layer files of the target video file from the content server respectively through the target macro base station and the target micro base station based on a backhaul link; Send the base layer file of the target video file to the target user through the target macro base station by using allocated first orthogonal channel resources, and send at least one enhancement layer file of the target video file to the target user through the target micro base station by using allocated second orthogonal channel resources.

4. The method according to claim 1, characterized in that The method further includes: Model the preset cellular network, where the preset cellular network includes: at least one macro base station, at least one micro base station, the target user, and at least one eavesdropper; Determine the first secure caching auxiliary data rate of the base layer file according to the first request probability, the first caching probability, the first successful transmission probability of sending the base layer file of the at least some video files, the secrecy outage probability, and the first minimum caching auxiliary data rate of the base layer file of the at least some video files; Determine the second secure caching auxiliary data rate of the enhancement layer file according to the second request probability, the second caching probability, the second successful transmission probability of sending the enhancement layer file of the at least some video files, and the second minimum caching auxiliary data rate of the enhancement layer file of the at least some video files; Determine the target secure caching data rate of the preset cellular network according to the first secure caching auxiliary data rate and the second secure caching auxiliary data rate, where the target secure caching data rate is used to indicate the performance of caching and transmitting video files when there is an eavesdropper in the preset cellular network.

5. The method according to claim 4, characterized in that, The method further includes: Calculate a first received signal-to-interference ratio (SIR) of the target user for receiving the base layer file according to the small-scale channel fading and distance between the target user and the target macro base station, and the small-scale channel fading and distance between the target user and other macro base stations; Determine a first probability density function of the distance between the target macro base station and the target user according to the density of the at least one macro base station; Calculate a first successful transmission probability of sending each base layer file according to the first received SIR and the first probability density function; 6. The method according to claim 4, wherein The method further includes: Calculate a second received SIR of the target user for receiving the enhancement layer file according to the small-scale channel fading and distance between the target user and the target micro base station, and the small-scale channel fading and distance between the target user and other micro base stations; Determine a second probability density function of the distance between the target micro base station and the target user according to the density of the at least one micro base station; Calculate a second successful transmission probability of sending each enhancement layer file according to the second received SIR and the second probability density function; 7. The method according to claim 4, wherein The method further includes: Determine a third received SIR of each eavesdropper according to the channel fading and distance between each eavesdropper and the macro base station being eavesdropped, and the channel fading and distance between each eavesdropper and the macro base stations not being eavesdropped; Calculate the secrecy outage probability according to the density of the at least one eavesdropper, the density of the at least one macro base station, and the third received SIR; 8. The method according to claim 4, wherein The method further includes: Calculate a first minimum caching-assisted data rate according to the transmission bandwidth of the target macro base station and the minimum reception threshold of the base layer file; 9. The method according to claim 4, wherein The method further includes: Calculate a second minimum caching-assisted data rate according to the transmission bandwidth of the target micro base station and the minimum reception threshold of the enhancement layer file; 10. A secure video transmission device based on scalable video coding, characterized in that, The apparatus includes: A caching module, configured to hierarchically cache the base layer file and multiple enhancement layer files of at least part of the video files in the content server in the target macro base station and the target micro base station of a preset cellular network respectively according to a preset caching policy; A determination module, configured to determine whether the at least part of the video files include a target video file according to a video acquisition request sent by a target user; A sending module, configured to, if the at least part of the video files include the target video file, send the base layer file of the target video file to the target user through the target macro base station, and send at least one enhancement layer file of the target video file to the target user after superposition by using a non-orthogonal transmission method through the target micro base station.

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