CN-116367241-B - Content placement and transmission optimization method based on scalable video coding

CN116367241BCN 116367241 BCN116367241 BCN 116367241BCN-116367241-B

Abstract

Embodiments of the present disclosure relate to an optimization method for content placement and transmission based on scalable video coding. The method comprises the steps of constructing a wireless cache network, transmitting a cached file to edge equipment by a macro base station in a content placement stage, sending request information to the edge equipment in a cell by a user in a content transmission stage, directly transmitting the request content to the user by the edge equipment if the request content is cached by the edge equipment, directly transmitting the request content to the user by the macro base station if the request content is not stored by the edge equipment, constructing and solving an optimization problem of minimizing the transmission delay of the user in the content placement stage to obtain an optimal cache strategy, and establishing an optimization problem of maximizing the user and the rate and solving the optimization problem in a content layer transmission stage to obtain the optimal transmission strategy. The embodiment of the disclosure effectively improves the efficiency of file transmission, reduces the transmission delay and improves the service quality of users.

Inventors

ZHANG XUEWEI
ZHANG LIN
REN YUAN
JIANG FAN
WANG JUNXUAN

Assignees

西安邮电大学

Dates

Publication Date: 20260512
Application Date: 20230328

Claims (8)

1. A method for optimizing content placement and transmission based on scalable video coding, the method comprising: the method comprises the steps of constructing a wireless cache network, wherein the wireless cache network comprises a core network, a macro base station, a user and edge equipment; In the content placement stage, the macro base station transmits the cached file to the edge equipment, in the content transmission stage, a user sends request information to the edge equipment in the cell, if the edge equipment has cached the request content, the edge equipment directly transmits the request content to the user, and if the edge equipment does not store the request content, the macro base station directly transmits the request content to the user; in the content placement stage, constructing and solving an optimization problem of minimizing user transmission delay to obtain an optimal caching strategy, wherein the method comprises the following steps: Constructing a time delay optimization model based on the minimized transmission time delay of the macro base station; Converting the time delay optimization model to a convex problem model; Solving the convex optimization problem after conversion to obtain an optimal caching strategy; Wherein, determining the minimum transmission delay D of the macro base station under the assistance of the edge equipment according to the formula (1): (1) Wherein, the Representing request No The first of the files The probability of the layer is 0, 1; a buffer indicator variable representing a binary system; Representing the cache file size; representing a transmission rate of the edge device; representing a transmission rate of the backhaul link; Representing the transmission rate of the macro base station; representing the capacity of the edge device; And in the content layer transmission stage, establishing an optimization problem for maximizing the user and the rate, and solving the optimization problem to obtain an optimal transmission strategy.
2. The method for optimizing content placement and transmission based on scalable video coding according to claim 1, wherein the step of converting the delay optimization model into a convex problem model comprises: introducing relaxation variables So that The original optimization problem can be translated into: (2) Wherein, the Is a relaxation variable.
3. The method for optimizing content placement and transmission based on scalable video coding according to claim 2, wherein the step of establishing and solving an optimization problem that maximizes users and rates, resulting in an optimal transmission strategy, comprises: constructing a signal transmission model according to channel conditions; and obtaining an expression of the user and the rate according to the transmission signal, constructing an optimization problem for maximizing the user and the rate, solving the constructed optimization problem, and obtaining an optimal beam forming vector.
4. The method for optimizing content placement and transmission based on scalable video coding according to claim 3, wherein the step of constructing a signal transmission model according to channel conditions comprises: When the cache file is acquired from the edge device according to the formula (3) Request by individual user Signal-to-noise ratio of layers: (3) Wherein, the Representing all edge devices and the first in the network Channel gain vectors between the individual users, Representing all edge devices and the first Channel gain vectors between the edge devices; representing a set of beamforming vectors; representing a user Request for Time and edge device Beamforming vectors in between; is additive white gaussian noise; when the request file is acquired from the macro base station according to the formula (4) Request by individual user Signal-to-noise ratio of layers: (4) Wherein, the Indicating base station and the th Channel gain between individual users; Represent the first Request by individual user Beamforming vector at layer time; is the variance of additive white gaussian noise.
5. The method for optimizing content placement and transmission based on scalable video coding according to claim 4, wherein the steps of obtaining an expression of a user and a rate from a transmission signal, and constructing an optimization problem solving the constructed optimization problem maximizing the user and the rate, and obtaining an optimal beamforming vector, comprise: determining a sum rate of the maximized users according to formula (5): (5) Wherein, the And Respectively representing the maximum transmitting power of the buffer equipment and the base station; And Respectively showing the buffer device and the base station as the first Transmission of the first user The lowest quality of service that needs to be met at layer time.
6. The method for optimizing content placement and transmission based on scalable video coding according to claim 5, wherein the non-convex problem is converted into a convex problem in the form of a second order cone programming by a transformation method of semi-positive relaxation, continuous convex approximation and geometric mean inequality, and solved by a CVX solver to obtain the beamforming matrix.
7. The method of optimizing content placement and transmission based on scalable video coding according to claim 6, wherein if the rank of the beamforming matrix is 1, eigenvalue decomposition is used to obtain the optimal beamforming vector.
8. The method of optimizing content placement and transmission based on scalable video coding according to claim 7, wherein if the rank of the obtained beamforming matrix is not 1, the method of gaussian randomization is used to obtain the optimal beamforming vector.

Description

Content placement and transmission optimization method based on scalable video coding Technical Field The embodiment of the disclosure relates to the technical field of wireless communication, in particular to an optimizing method for content placement and transmission based on scalable video coding. Background In recent years, the explosive development of the mobile internet and the diversification of multimedia services place higher demands on the quality of service, including system throughput, transmission delay and mass connections. To address these challenges, wireless caching is considered a promising technology, becoming increasingly attractive in fifth generation mobile communications. Video traffic typically has strong redundancy characteristics, so we can improve traffic transmission efficiency through wireless buffering. With caching, trending content can be delivered to users more recently and faster. Performing cache placement during off-peak periods of the network, performing content delivery when content requests occur, edge caching provides additional performance gains that are shorter in transmission distance than from a remote centralized server. In the related art, there is an increasing demand for multi-quality video services due to the limitation of backhaul capacity and the variation of user demands. For example, some people need to delay short standard definition video when watching sports news, and high definition video when watching movies. Accordingly, there is a need to improve one or more problems in the related art as described above. It is noted that this section is intended to provide a background or context for the technical solutions of the present disclosure as set forth in the claims. The description herein is not admitted to be prior art by inclusion in this section. Disclosure of Invention It is an object of embodiments of the present disclosure to provide an optimized method of content placement and transmission based on scalable video coding, which overcomes one or more of the problems due to the limitations and disadvantages of the related art, at least to some extent. According to an embodiment of the present disclosure, there is provided an optimizing method for content placement and transmission based on scalable video coding, the method including: the method comprises the steps of constructing a wireless cache network, wherein the wireless cache network comprises a core network, a macro base station, a user and edge equipment; In the content placement stage, the macro base station transmits the cached file to the edge equipment, in the content transmission stage, a user sends request information to the edge equipment in the cell, if the edge equipment has cached the request content, the edge equipment directly transmits the request content to the user, and if the edge equipment does not store the request content, the macro base station directly transmits the request content to the user; Based on the content placement process, constructing and solving an optimization problem of minimizing the user transmission delay, and obtaining an optimal caching strategy; and establishing and solving an optimization problem of maximizing the user and the rate to obtain an optimal transmission strategy. In an embodiment of the present disclosure, based on the content placement process, constructing and solving an optimization problem that minimizes a user transmission delay, and obtaining an optimal caching policy includes: Constructing a time delay optimization model based on the minimized transmission time delay of the macro base station; Converting the time delay optimization model, and converting the time delay optimization model into a convex problem model; And obtaining an optimal caching strategy based on the converted time delay optimization model. In an embodiment of the present disclosure, the minimum transmission delay D of the macro base station under the assistance of the edge device is determined according to formula (1): Wherein p f,l represents the probability of requesting the first layer of the f-th file, the value is [0,1], z f,l represents a binary buffer indicating variable, s f,l represents the buffer file size, R h represents the transmission rate of the edge device, R b represents the transmission rate of the backhaul link, R m represents the transmission rate of the macro base station, and D h represents the capacity of the edge device. In an embodiment of the disclosure, the step of converting the time delay optimization model into a convex problem model includes: introducing a relaxation variable t to ensure that D is less than or equal to t, and converting the original optimization problem into: wherein t is a relaxation variable. In an embodiment of the present disclosure, the steps of establishing an optimization problem that maximizes the user and the rate and solving to obtain an optimal transmission policy include: constructing a signal transmis