KR102648108B1 - Method for providing collaborative http adaptive streaming using wifi network based on software-defined networking and apparatus thereof - Google Patents

Abstract

The cooperative HTTP adaptive streaming device through an SDN-based multiple Wi-Fi network of the present invention includes a processor and a memory storing at least one command executed through the processor, and the at least one command is a step in which the processor requests streaming by UEs (USER ENTITY) considering their network conditions; the sum of the time slots used by UEs (USER ENTITY) to determine whether congestion has occurred in the network is determined by each AP ( ACCESS POINT) Includes the step of checking if it is larger than the timeslot, initializing each variable when congestion occurs, and calculating the bitrate through the slope. Video that combines MPEG-DASH and SDN in a multi-Wi-Fi environment It is a device that determines the bit rate of video segments that maximizes the sum of video quality of all users receiving service on a streaming system.

Description

Method and device for cooperative HTTP adaptive streaming over SDN-based multiple Wi-Fi networks

The present invention is a technology for improving users' QoE (Quality of experience) by using SDN (Software-Defined Networking) and DASH (Dynamic Adaptive Streaming over HTTP) technologies on multiple Wi-Fi networks.

Recently, as platforms such as YouTube and Facebook have grown rapidly around the world, network managers are experiencing difficulties due to increased video traffic.

DASH (Dynamic Adaptive Streaming over HTTP) is a technology that streams high-quality, seamless video by selecting the bitrate of the video considering the user's available network resources. DASH divides the video into segments at regular time intervals to take into account time-varying network conditions, and encodes the segments at various bitrates and stores them in the DASH Server to provide video adaptively to the network situation. The DASH Server describes and stores the length and bitrate information of the stored segments in an XML format MPD (Media Presentation Description) file. The user receives the MPD file from the DASH Server and selects a segment appropriate for the user's network situation. You can receive uninterrupted, high-quality streaming service by requesting and receiving selected segments from DASH Server.

SDN (Software-Defined Networking) is a centralized system that reduces complexity by separating the control unit and transmission unit that were combined in the existing traditional network structure, and allows the entire network to be controlled through software rather than hardware through Open Flow technology. . This structure is characterized by being able to manage resources by simultaneously considering not only the network status of a single user but also the information of all members participating in the network.

DASH determines video quality by considering only the network situation of a single user. Therefore, if selfish users monopolize network resources, a problem may occur where the sum of the video quality of all users participating in the network is lowered (P. Georgopopulos, Y. Elkhatib, M. Broadnet, M.Mu and N . Race, “Towards network-wide QoE fairness using openflow-assisted adaptive video streaming”, in Proceedings of ACM FhMn, pp. 15-20, 2013). There is research to solve the resource unfairness problem by combining existing DASH with SDN (H. Noh, H. Lee, Y. Go. H. Park, J. Lee, J. Kim, H. Song, “Congestion- aware HTTP adaptive streaming system over SDN-enabled Wi-Fi network”, Wiley Online Library. Concurrency and Computation, April. 2019). In this study, SDN periodically collects network resource information, and when it is determined that congestion has occurred, it distributes resources and prevents congestion by considering the network situation from an overall perspective (D. Kreutz et al., “Software-defined networking : A comprehensive survey,” Proc. IEEE, vol. 103, no. 1, pp. 14-76, Jan. 2015.) Through this, problems caused by selfish users in existing DASH can be solved. However, because this study only considered a single AP, it did not consider an efficient resource distribution method in a multi-AP situation. SDNHAS study (A. Bentaleb, A. C. Begen, R. Zimmermann, and S. Harous, “SDNHAS: An SDN-enabled architecture to optimize QoE in HTTP adaptive streaming”, IEEE Trans. Multimedia, vol. 19, no. 10, pp . 2136-2151, Oct. 2017) collects overall network resource information through SDN, divides users into several groups using the POMDP (Partially Observable Markov Decision Process) method, and provides video services to users according to their group. Suggest a way to receive . This study has the advantage of improving the video quality of all users participating in the network through clustering, but has the disadvantage of not considering the characteristics of single users. MP-DASH (B. Han, F. Qian, L. Ji, and V. Gopalakrishnan, “MP-DASH: Adaptive video streaming over preference-aware multipath,” in Proc. 12th Int. Conf. Emerg. Netw. Exp. (CoNEXT), Irvine, CA, USA, 2016, pp. 129-143. [Online]. Available: https://doi.org/10.1145/2999572.2999606.) uses multi-path access to increase network bandwidth utilization. This is a study using a method. In this study, MPTCP (Multipath TCP) was used to improve the overall video quality (A. Ford, C. Raiciu, M. Handley, and O. Bonaventure. TCP Extensions for Multipath Operation with Multiple Addresses. RFC 6824, 2013) .

P. Georgopopulos, Y. Elkhatib, M. Broadnet, M.Mu and N. Race, “Towards network-wide QoE fairness using openflow-assisted adaptive video streaming”, in Proceedings of ACM FhMn, pp. 15-20, 2013. H. Noh, H. Lee, Y. Go. H. Park, J. Lee, J. Kim, H. Song, “Congestion-aware HTTP adaptive streaming system over SDN-enabled Wi-Fi network”, Wiley Online Library. Concurrency and Computation, April. 2019. D. Kreutz et al., “Software-defined networking: A comprehensive survey,” Proc. IEEE, vol. 103, no. 1, pp. 14-76, Jan. 2015. A. Bentaleb, A. C. Begen, R. Zimmermann, and S. Harous, “SDNHAS: An SDN-enabled architecture to optimize QoE in HTTP adaptive streaming”, IEEE Trans. Multimedia, vol. 19, no. 10, pp. 2136-2151, Oct. 2017. B. Han, F. Qian, L. Ji, and V. Gopalakrishnan, “MP-DASH: Adaptive video streaming over preference-aware multipath,” in Proc. 12th Int. Conf. Emerg. Netw. Exp. Technol. (CoNEXT), Irvine, CA, USA, 2016, pp. 129-143. [Online]. Available: https://doi.org/10.1145/2999572.2999606. A. Ford, C. Raiciu, M. Handley, and O. Bonaventure. TCP Extensions for Multipath Operation with Multiple Addresses. RFC 6824, 2013.

The purpose of the present invention to solve the above problems is that the SDN controller periodically monitors network traffic information from an AP (Access Point) and uses the monitored information to determine the video bitrate and AP (ACCESS POINT) connection ratio. To provide a cooperative HTTP adaptive streaming method and device through SDN-based multiple Wi-Fi networks that improves QoE by controlling .

A cooperative HTTP adaptive streaming device through SDN-based multiple Wi-Fi networks according to an embodiment of the present invention includes a processor; and a memory storing at least one instruction to be executed through a processor. Includes, wherein the at least one command includes: requesting streaming from user entities (UEs) considering their network conditions; Checking whether the sum of time slots used by UEs (USER ENTITY) is greater than each AP (ACCESS POINT) timeslot to determine whether congestion has occurred in the network; Initializing each variable when congestion occurs; calculating the bit rate through the gradient; It may be a device for determining the bitrate of video segments that maximizes the sum of video quality of all users served on a video streaming system combining MPEG-DASH and SDN in a multi-Wi-Fi environment.

The device includes a DASH Client that requests a segment from the Media Server using a bitrate calculated by an SDN Application algorithm; AP Agent that periodically collects network resource information from DASH Client and provides the collected information to SDN Application; SDN Application that calculates the bitrate of the segment requested by the DASH Client by considering the entire network situation through an algorithm and then responds; Media Server that provides video encoded at the requested bitrate to the DASH Client when a segment request is received; may include.

DASH Client is a UE (User Entity) that actually receives streaming services, and is equipped with an additional wireless LAN interface to implement multipath access. Each wireless LAN interface is connected to one AP (ACCESS POINT), and the Multipath Agent Video segments to be received through the module are received by dividing them considering the network status of each AP (ACCESS POINT), and when requesting streaming service, an MPD file containing segment information of each video can be requested from the Media Server 40.

The MPD file is an XML format file containing the length, encoding bitrate, and URL information of each segment, and can provide information on which segment the DASH Client should select according to time-varying network conditions.

The SDN Application responds after calculating the bitrate of the segment requested by the DASH Client, taking into account the entire network situation through an algorithm. Afterwards, the DASH Client sends the segment to the Media Server using the bitrate calculated by the SDN Application through the algorithm. You can request it.

The AP Agent uses a bandwidth model based on the RSSI (Received Signal Strength Indication) signal for network resource information, and the bandwidth model is determined by curve fitting through the measured bandwidth and RSSI values obtained from the AP Agent, and EWMA Bandwidth can be stabilized and used by applying the (Exponentially Weighted Moving Average) model.

SDN Application periodically collects resources from all AP Agents through the Traffic Info Collector module, and based on the collected resources, considers the overall network situation through the Streaming Optimizer software module to select the segment bitrate and multi-path of DASH Clients. You can determine the ratio of how many segments should be received through which path.

The Media Server consists of an MPD file containing information on segments that can be provided to the DASH Client, and a web server that stores video segments encoded at various bitrates. When a segment request is received, the video encoded at the requested bitrate can be provided to DASH Client.

The cooperative HTTP adaptive streaming method through SDN-based multiple Wi-Fi networks according to another embodiment of the present invention is an SDN-based multiple Wi-Fi network of a video streaming system that combines MPEG-DASH and SDN in a multiple Wi-Fi environment. In the cooperative HTTP adaptive streaming method through a network, UEs (USER ENTITY) request streaming in consideration of their network conditions; Checking whether the sum of time slots used by UEs (USER ENTITY) is greater than each AP timeslot to determine whether congestion has occurred in the network; Initializing each variable when congestion occurs; calculating the bit rate through the gradient; It may be a method of determining the bit rate of a video segment that maximizes the sum of video quality of all users receiving the service.

In the step of calculating the bit rate through the slope, Equation 10 derived through the Lagrange multiplier method can be used, and the bandwidth of the virtual AP (ACCESS POINT) of each UE (USER ENTITY) can be calculated through Equation 11.

The step of calculating the bit rate through the slope includes calculating the network resources in use for each AP (ACCESS POINT): calculating whether buffer underflow is present and checking whether buffer underflow occurs only at a specific AP (ACCESS POINT); And if underflow occurs in only one AP (ACCESS POINT) and no underflow occurs in the remaining APs (ACCESS POINT), the network resources of all APs (ACCESS POINT) are not utilized efficiently, and the segment sharing ratio re-adjusting; may include.

In the step of readjusting the segment sharing ratio, in order to find a UE (USER ENTITY) to adjust the segment ratio, an AP (ACCESS POINT) with no available resources for each UE (USER ENTITY) and an AP with available resources (ACCESS POINT) calculating the bandwidth ratio and sorting in ascending order; may include.

In the step of re-adjusting the segment sharing ratio, if underflow occurs for all APs (ACCESS POINT), the bit rate has been set high and must be reduced. Conversely, the bit rate must be reduced for all APs (ACCESS POINT). ) If there are a lot of available network resources remaining, it may include a step of increasing them so that the network resources can be fully utilized.

The step of adjusting the gradient using binary search includes increasing the quality of the image by reducing the gradient when there are sufficient resources; and examining whether the difference between the adjusted slope and the slope obtained in the previous loop is small; Terminating the entire algorithm if the difference between the adjusted slope and the slope obtained in the previous loop is less than a predetermined size; may include.

The step of adjusting the gradient using binary search includes increasing the gradient when resources are insufficient and then calculating the bit rate through the gradient; may include.

To determine whether congestion has occurred in the network, the step of checking whether the sum of time slots used by UEs (USER ENTITY) is greater than the time slots of each AP (ACCESS POINT) is to determine whether the sum of time slots used is greater than the AP (ACCESS POINT) time slot. If it is larger than the timeslot, it means that there are no resources available at the AP (ACCESS POINT), and if even one AP (ACCESS POINT) meets the condition, it is considered that congestion has occurred; If no congestion occurs, streaming is provided at the bitrate requested by the user and terminating the algorithm; and when congestion occurs, proceeding to initializing each variable when congestion occurs; may include.

In the step of initializing each variable when congestion occurs, the slope value is set to the middle value between the lower slope value and the upper slope limit to set the initial value, and the previous slope value is used to determine the algorithm termination condition to set the upper slope limit value. Initializing the AP (ACCESS POINT), which provides strong RSSI signal strength, with a segment sharing ratio of 1; may include.

The above method is a video streaming method that utilizes SDN in a multi-Wi-Fi environment to maximize not only the user's QoE but also the utilization of the AP (ACCESS POINT). POINT) is treated as if there is only one AP (ACCESS POINT), and when using a virtual AP (ACCESS POINT), the slope to be obtained is reduced to one, so it is expressed as Equation 8, Equation 9, and Equation 10, and Equation Using the relationship between bit rate and slope expressed as 10, the bit rate of UEs (USER ENTITY) can be obtained by adjusting the slope, and the bit rate values that satisfy the constraints can be obtained using binary search for the slope.

The method is to integrate the bandwidth between the existing UE (USER ENTITY) and AP (ACCESS POINT) by setting one AP (ACCESS POINT), and the integrated bandwidth is between UE (USER ENTITY) and AP (ACCESS POINT). It can be defined as in Equation 11, considering the usage ratio of .

It may be a computer-readable recording medium for implementing a program of the cooperative HTTP adaptive streaming method through SDN-based multiple Wi-Fi networks according to any one of the preceding clauses.

According to the present invention, adaptive video streaming technology based on SDN and DASH can improve QoE by improving the video quality of members participating in the network by considering not only a single user but also the entire network.

Additionally, by preventing the bandwidth of a specific Access Point from being wasted, costs can be reduced by preventing network managers from opening unnecessary additional Access Points.

Figure 1 is a structural diagram of a cooperative HTTP adaptive streaming device through an SDN-based multiple Wi-Fi network according to an embodiment of the present invention.
FIG. 2 is an image of a virtual AP (ACCESS POINT) according to the embodiment of FIG. 1.
Figure 3 is an operation flow chart according to the embodiment of Figure 1.
Figure 4 is a flowchart of a cooperative HTTP adaptive streaming method through SDN-based multiple Wi-Fi networks according to an embodiment of the present invention.
Figure 5 is an image of a pseudo code algorithm for maximizing the QOE of the DASH Client (10).
Figure 6 is an image of a pseudo code algorithm that adjusts the segment download rate of the DASH Client (10).
Figure 7 is an image of a pseudo code algorithm that adjusts the slope value of the DASH Client (10).
Figure 8 is a configuration diagram of a cooperative HTTP adaptive streaming device through an SDN-based multiple Wi-Fi network according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention. While describing each drawing, similar reference numerals are used for similar components.

Terms such as first, second, A, B, etc. may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, the second component may also be named a first component without departing from the scope of the present invention. The term “and/or” includes any of a plurality of related stated items or a combination of a plurality of related stated items.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. In order to facilitate overall understanding when describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

Figure 1 is a structural diagram of a cooperative HTTP adaptive streaming device through an SDN-based multiple Wi-Fi network according to an embodiment of the present invention.

Referring to Figure 1, a cooperative HTTP adaptive streaming device through an SDN-based multiple Wi-Fi network according to an embodiment of the present invention includes DASH Client (10), AP Agent (20), SDN Application (30), and Media It consists of four elements: Server (40).

The DASH Client 10 is actually a UE (User Entity) that receives streaming services. In the present invention, an additional wireless LAN interface was installed in the DASH Client (10) to implement multi-path access, and each wireless interface was configured to be connected to one AP (ACCESS POINT). Through the Multipath Agent module of the DASH Client (10), the video segments to be received are divided and received, taking into account the network status of each AP (ACCESS POINT). When requesting a streaming service, the DASH Client (10) requests an MPD file containing segment information for each video from the Media Server (40). The MPD file is an XML format file containing the length, encoding bitrate, and URL information of each segment, and provides information on which segment the DASH Client (10) should select according to time-varying network conditions. The bitrate of the segment selected by traditional DASH does not consider the overall network situation, which can lead to unfair network resource distribution problems. Therefore, each time the DASH Client (10) requests a segment, it is necessary to check with the SDN Application (30) whether the bit rate of the segment it requested is appropriate considering the overall network situation. The SDN Application (30) calculates the bitrate of the segment requested by the DASH Client (10) by considering the entire network situation through an algorithm and then responds. Afterwards, the DASH Client (10) requests a segment from the Media Server (40) using the bitrate calculated by the SDN Application (30) through an algorithm.

Network resource information is periodically collected from the DASH Client (10) through the Traffic Info Transmitter module (21) of the AP Agent (20) and the collected information is provided to the SDN Application (30). Since the entire network situation must be considered, the DASH Client (10) must be able to identify AP Agents (20) that are not connected. To solve this problem, the network resource information used a bandwidth model based on the RSSI (Received Signal Strength Indication) signal, and the bandwidth model was curve fitted using the measured bandwidth and RSSI values obtained from the AP Agent (20). It is decided. In addition, since network conditions tend to change rapidly over time, and the quality of video may change irregularly, the EWMA (Exponentially Weighted Moving Average) model is applied to stabilize the bandwidth.

SDN Application (30) periodically collects resources from all AP Agents (20) through the Traffic Info Collector module (31). Based on the collected resources, the overall network situation is considered through the Streaming Optimizer software module 32 to determine the segment bitrate of DASH Clients 10 and the ratio of how many segments should be received through which path among multiple paths.

The Media Server 40 is a web server that stores an MPD file 41 containing information on segments that can be provided to the DASH Client 10 and video segments 42 encoded at various bit rates. When a segment request is received, video encoded at the requested bitrate is provided to the DASH Client (10).

In equation 1 Is This refers to the bitrate selected by the second UE (USER ENTITY) for streaming, Is The first UE (USER ENTITY) is This refers to the rate of reception through the second AP, is a set of UE (USER ENTITY), means a set of AP (ACCESS POINT). Equation 2 expresses the image quality in the form of a logarithmic function through PSNR (Peak Signal-to-Noise Ratio), and the coefficient has different values depending on the type of video requested by the UE (USER ENTITY), bit rate, and segment index, and is determined by curve fitting the PSNR value of the actual video segment. Therefore, through Equation 1 and Equation 2, the present invention maximizes the sum of the video quality of all UEs (USER ENTITY). Bitrate of the second user class The second user Rate of reception through the first AP (ACCESS POINT) It is a matter of deciding. At this time, the sum of the ratios at which one UE (USER ENTITY) receives segments from multiple APs (ACCESS POINT) is 1 (Equation 3), and the bit rate adjusted by the SDN Application (30) ) is the bitrate requested by the client ( ) cannot be exceeded (Equation 4). Additionally, to prevent buffer underflow from occurring, the timeslot is a buffer control function. Via buffer limit ( ) and the buffer median of DASH Clients (10) ( ) to compare and adjust. If the amount of data accumulated in the buffer is small compared to the buffer limit, the bit rate for users is lowered by reducing the time slot to prevent video interruption. Conversely, if the amount of data accumulated in the buffer is large, more buffers can be accumulated, thereby increasing the video bit rate and improving video quality. To provide these features is defined by Equation 6, which is a third-order polynomial as follows.

In the above equation Is is the coefficient of Also, to avoid sudden changes in quality, The output range of [- / 2, / 2].

The given problem uses the Lagrange multiplier to find the solution. The Lagrange multiplier method is a method of geometrically obtaining a solution that satisfies constraints and maximizes or minimizes the objective function. The optimal solution is assumed to be at the point where the two functions meet, and the solution is obtained by adjusting the slope (λ). If the previously defined problem definition is expressed through the Lagrange multiplier method, it is as shown in Equation 7.

As can be seen in Equation 7, one gradient occurs per AP. This is a problem that cannot be solved in polynomial time as the number of APs (ACCESS POINT) increases because the complexity is high due to the dependence between multiple gradients. To solve this high time complexity, the problem is solved by introducing the virtual AP (ACCESS POINT) concept as shown in Figure 2.

Figure 2 is an image of a virtual AP (ACCESS POINT) according to an embodiment of the present invention.

Referring to FIG. 2, virtual AP (Virtual Access Point) is a method of solving the problem by treating multiple APs (ACCESS POINT) as if only one AP (ACCESS POINT) exists. When using a virtual AP (ACCESS POINT), the slope to be obtained can be simplified as follows by reducing it to one.

The relationship between bit rate and slope can be expressed as Equation 10, and the bit rate of UEs (USER ENTITY) is obtained by adjusting the slope using the equation. The gradient uses binary search to find bitrate values that satisfy the constraints. Additionally, the bandwidth between the existing UE (USER ENTITY) and AP (ACCESS POINT) must be integrated by creating one AP (ACCESS POINT). Integrated bandwidth ( ) is defined as Equation 11 below, considering the usage ratio between UE (USER ENTITY) and AP (ACCESS POINT).

After applying the virtual AP (ACCESS POINT) concept, the problem is redefined as follows.

Figure 4 is a flowchart of a cooperative HTTP adaptive streaming method through SDN-based multiple Wi-Fi networks according to an embodiment of the present invention, and Figure 5 is an image of a pseudocode algorithm for maximizing the QOE of the DASH Client 10. Figure 6 is an image of a pseudo code algorithm that adjusts the segment download rate of the DASH Client (10), and Figure 7 is an image of a pseudo code algorithm that adjusts the slope value of the DASH Client (10).

With reference to FIGS. 3 to 7, a control variable determination algorithm of a cooperative HTTP adaptive streaming method through an SDN-based multiple Wi-Fi network according to an embodiment of the present invention will be described.

Referring to Figure 3, an overall flow chart of the control variable determination algorithm for solving the above-described problem is shown.

Step 1000: UE (USER ENTITY) considers their network situation Select to request streaming.

Step 1100: Sum of timeslots used by UEs (USER ENTITY) to determine whether congestion has occurred in the network ( ) is each AP (ACCESS POINT) timeslot ( ) Check whether it is greater than . If the sum of used timeslots is greater than the AP (ACCESS POINT) timeslot, this means that there are no resources available at the AP (ACCESS POINT). If even one AP (ACCESS POINT) meets the condition, congestion is considered to have occurred. . When no congestion occurs Is , streaming is provided at the bitrate requested by the user, and the algorithm ends. If congestion occurs, proceed to step 1200.

Step 1200: When congestion occurs, each variable is initialized as shown in lines 6 to 9 of FIG. 5. To set the initial value, the slope value ( ) is the lower limit of the slope ( ) and the upper slope value ( ) is set to the middle value. Previous slope value ( ) is used to determine the algorithm termination condition and is initialized to the upper slope value. Segment sharing ratio ( ) initializes the AP (ACCESS POINT), which provides strong RSSI signal strength, to the value of 1.

Step 1300: Gradient using Equation 10 derived through the Lagrange multiplier method ( ) via bitrate ( ) is calculated. Because DASH segments are encoded as discrete values, the calculated bitrate ( ) by quantizing the bitrate ( ) Select the value that is closest to .

Step 1310: Bandwidth of the virtual AP (ACCESS POINT) of each UE (USER ENTITY) through Equation 11 ( ), and the network resources in use for each AP (ACCESS POINT) ( ) is calculated. Afterwards, calculate whether the buffer underflows ( ), check whether buffer underflow occurs only at a specific AP (ACCESS POINT) (step 1311). If underflow occurs in only one AP (ACCESS POINT) but does not occur in the remaining APs (ACCESS POINT), the network resources of all APs (ACCESS POINT) are not utilized efficiently, and the segment sharing ratio ( ) must be adjusted again (step 1312). Perform step 1315 to readjust. If not, step 1320 is performed.

Step 1315: Segment split ratio ( ), an AP (ACCESS POINT) with no available resources and an AP (ACCESS POINT) with available resources for each UE (USER ENTITY) to find a UE (USER ENTITY) to adjust the segment ratio as shown in Figure 6. Calculate the bandwidth ratio and sort in ascending order. After sorting, adjust the segment ratio of the UE (USER ENTITY) with the lowest bandwidth ratio. The reason for adjusting the UE (USER ENTITY) with the lowest bandwidth ratio is to increase the resource usage of the AP (ACCESS POINT) with low resource use while greatly reducing the resources of the AP (ACCESS POINT) with high resource use.

Step 1320: If underflow occurs for all APs (ACCESS POINT), bitrate ( ) is set high, so it must be decreased. Conversely, for all APs (ACCESS POINTs), if there are a lot of available network resources for APs (ACCESS POINTs), they must be increased to fully utilize the network resources. In order to perform this process, binary search is used as shown in Figure 7 to find the gradient ( ). If there are sufficient resources, the slope ( ) to increase the quality of the image (step 1321). At this time, it is checked whether the difference between the adjusted slope and the slope obtained in the previous loop is small (epsilon or less) (step 1322). If the difference is small, it is determined that the bit rate can no longer be adjusted through slope adjustment, and the entire algorithm is terminated (step 1323). If resources are insufficient, increase the slope and then perform step 1300 (step 1324).

Figure 8 is a configuration diagram of a cooperative HTTP adaptive streaming device 100 through an SDN-based multiple Wi-Fi network in an embodiment of the present invention.

Referring to FIG. 8, the cooperative HTTP adaptive streaming device 100 through an SDN-based multiple Wi-Fi network of an embodiment of the present invention includes a processor 110, a memory 120, and a transceiver (transceiver, 130). , may be configured to include an input interface device 140, an output interface device 150, a storage device 160, and a bus 170.

The cooperative HTTP adaptive streaming device 100 through an SDN-based multiple Wi-Fi network of the present invention includes a processor (processor). (110), including a memory 120 storing at least one command executed through the processor 110, wherein the at least one command is configured so that the processor, UEs (USER ENTITY) consider their network conditions. The step of requesting streaming, the step of checking whether the sum of the time slots used by UEs (USER ENTITY) is greater than the time slots of each AP to determine whether congestion has occurred in the network, and initializing each variable when congestion occurs. It is configured to perform the step of calculating the bit rate through the step and gradient.

The processor 110 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed.

Each of the memory 120 and the storage device 160 may be comprised of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 120 may be comprised of at least one of read only memory (ROM) and random access memory (RAM).

Additionally, the cooperative HTTP adaptive streaming device 100 through an SDN-based multiple Wi-Fi network may include a transceiver 130 that performs communication through a wireless network.

In addition, the cooperative HTTP adaptive streaming device 100 through an SDN-based multiple Wi-Fi network may further include an input interface device 140, an output interface device 150, a storage device 160, etc.

Each component included in the cooperative HTTP adaptive streaming device 100 through an SDN-based multiple Wi-Fi network is connected by a bus 170 and can communicate with each other.

Examples of the cooperative HTTP adaptive streaming device 100 through an SDN-based multiple Wi-Fi network of the present invention include a desktop computer, a laptop computer, a laptop, and a smartphone capable of communication. (smart phone), tablet PC, mobile phone, smart watch, smart glass, e-book reader, PMP (portable multimedia player), portable game console, navigation ( navigation) device, digital camera, digital multimedia broadcasting (DMB) player, digital audio recorder, digital audio player, digital video recorder, digital video player ( It may be a digital video player), PDA (Personal Digital Assistant), etc.

The operations of the method according to the embodiments of the present invention can be implemented as a computer-readable program or code on a computer-readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system. Additionally, computer-readable recording media can be distributed across networked computer systems so that computer-readable programs or codes can be stored and executed in a distributed manner.

Additionally, computer-readable recording media may include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Program instructions may include not only machine language code such as that created by a compiler, but also high-level language code that can be executed by a computer using an interpreter, etc.

Although some aspects of the invention have been described in the context of an apparatus, it may also refer to a corresponding method description, where a block or device corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may also be represented by corresponding blocks or items or features of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as a microprocessor, programmable computer, or electronic circuit, for example. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

In embodiments, a programmable logic device (e.g., a field programmable gate array) may be used to perform some or all of the functionality of the methods described herein. In embodiments, a field programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described herein. In general, the methods are preferably performed by some hardware device.

Although the present invention has been described with reference to preferred embodiments of the present invention, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that it is possible.

Claims (20)

processor; and
A memory storing at least one instruction to be executed through a processor;
It includes, and by the at least one instruction, the processor,
Receiving a request from UEs (User Entities) to stream video at the bitrate of the segment selected by each UE;
Setting a plurality of access points (APs) of the UEs into one virtual AP (virtual AP, VAP) and calculating the bandwidth of the VAP based on the ratio in which each UE receives a segment;
calculating network resources being used by each AP based on the bandwidth;
In order to determine whether congestion has occurred in the network, determining whether the buffer underflow of each AP is performed by checking whether the sum of the time slots used by the UEs of each AP is greater than the corresponding AP timeslot;
If the buffer underflow occurs only in a specific AP, calculating the bandwidth ratio of the AP without available resources and the bandwidth ratio of the AP with available resources for each UE to find a UE to adjust the segment ratio;
Sorting all APs for each UE in ascending order of the bandwidth ratio;
increasing the segment ratio of the UE with the lowest bandwidth ratio after alignment in the sorting step;
If the difference between the slope of the Lagrange multiplier method for the segment ratio of the UE with the increased segment ratio and the slope for the segment ratio obtained in the previous loop is less than the reference value, the current bandwidth is not returned to the step of calculating the bandwidth of the VAP. terminating the process; and
If the buffer underflow occurs in all APs, reducing the ratio of all APs to receiving segments for each UE and then returning to the step of calculating the bandwidth of the VAP; performing,
Cooperative HTTP adaptive streaming devices over SDN-based multiple Wi-Fi networks. In claim 1,
In the step of calculating the bandwidth of the VAP, the processor
The bit rate is calculated using the slope (λ) of Equation 10 derived through the Lagrange multiplier method, the calculated bit rate is quantized, and the quantized bit rate and the most Select an approximate value and calculate the bandwidth of the virtual AP of each UE using Equation 11,

In equation 10,

is the bitrate selected by the ith UE for streaming,

represents the Peak Signal-to-Noise Ratio (PSNR) coefficient of the video segment requested by the ith UE, i is a random natural number, and N represents the set of UEs,
In equation 11,

is the integrated bandwidth, M is the set of APs,

is the segment ratio that the ith UE receives through the jth AP, i is a random natural number, and

represents the bandwidth that the i-th UE receives through the j-th AP, respectively.
Cooperative HTTP adaptive streaming devices over SDN-based multiple Wi-Fi networks. In claim 2,
When the slope is expressed in Equation 8 and Equation 9, the processor calculates the bit rate of each UE by adjusting the slope using the relationship between the bit rate and slope expressed in Equation 10. Do more,
Adjusting the slope includes finding bitrate values that satisfy constraints using binary search,

In Equation 8, L is the Lagrange multiplier (Lagrange mlutiplier), and the coefficient

and

has different values depending on the type, bit rate, and segment index of the video requested by the UE (USER ENTITY), and is determined by curve fitting the PSNR value of the actual video segment.

represents the video bitrate of the segment provided to the ith UE, respectively.
Cooperative HTTP adaptive streaming devices over SDN-based multiple Wi-Fi networks. In claim 3,
By setting all APs for each UE to one VAP, the integrated bandwidth of UEs and APs at each AP is defined as Equation 11 in consideration of the usage ratio between UEs and AP. SDN-based multiple Wi-Fi network Collaborative HTTP adaptive streaming devices via. In claim 1,
If the congestion occurs and the sum of time slots used by the UEs is greater than each AP timeslot, the processor initializes the ratio at which each UE shares segments and the slope of the segment ratio of each UE. Do more,
In the initializing step, the slope value is set to the middle value between the lower slope value and the upper slope limit value to set the initial value, and the previous slope value is initialized to the upper slope value for use in determining the algorithm termination condition, The segment sharing ratio includes initializing the AP that provides the strongest RSSI signal strength among all the APs to the value 1,
Cooperative HTTP adaptive streaming devices over SDN-based multiple Wi-Fi networks. In claim 1,
The processor further performs a step of increasing the ratio of all APs to receiving segments for each UE by a certain amount if available network resources remain for all APs.
Cooperative HTTP adaptive streaming devices over SDN-based multiple Wi-Fi networks. In claim 1,
The cooperative HTTP adaptive streaming device includes an SDN Application,
The SDN Application periodically collects resources from all AP Agents through the Traffic Info Collector module, and based on the collected resources, considers the overall network situation through the Streaming Optimizer software module to determine the segment bitrate and multipath of DASH Clients. It determines the ratio of how many segments should be received through which route.
Here, each DASH Client requests a segment from the Media Server using the bitrate calculated by the SDN Application through an algorithm,
The AP Agent periodically collects network resource information from the DASH Client and provides the collected information to the SDN Application,
When receiving a request for the segment, the Media Server provides video encoded at the requested bit rate to the DASH Client.
Cooperative HTTP adaptive streaming devices over SDN-based multiple Wi-Fi networks. In claim 7,
The Media Server consists of an MPD file containing information on segments that can be provided to the DASH Client, and a web server that stores video segments encoded at various bit rates.
Cooperative HTTP adaptive streaming devices over SDN-based multiple Wi-Fi networks. In a cooperative HTTP adaptive streaming method through SDN-based multiple Wi-Fi networks, which is performed by a processor of an SDN application of a video streaming system combining MPEG-DASH and SDN in a multiple Wi-Fi environment,
Receiving a request from UEs (USER ENTITIES) to stream video at the bitrate of the segment selected by each UE;
Setting a plurality of access points (APs) of the UEs into one virtual AP (virtual AP, VAP) and calculating the bandwidth of the VAP based on the ratio in which each UE receives a segment;
calculating network resources being used by each AP based on the bandwidth;
In order to determine whether congestion has occurred in the network, determining whether the buffer underflow of each AP is performed by checking whether the sum of the time slots used by the UEs of each AP is greater than the corresponding AP's timeslot;
If the buffer underflow occurs only in a specific AP, calculating the bandwidth ratio of the AP without available resources and the bandwidth ratio of the AP with available resources for each UE to find a UE to adjust the segment ratio;
Sorting all APs for each UE in ascending order of the bandwidth ratio;
increasing the segment ratio of the UE with the lowest bandwidth ratio after alignment in the sorting step;
If the difference between the slope of the Lagrange multiplier method for the segment ratio of the UE with the increased segment ratio and the slope for the segment ratio obtained in the previous loop is less than the reference value, the current bandwidth is not returned to the step of calculating the bandwidth of the VAP. terminating the process; and
If the buffer underflow occurs in all APs, reducing the ratio of all APs to receiving segments for each UE and then returning to the step of calculating the bandwidth of the VAP;
A cooperative HTTP adaptive streaming method over SDN-based multiple Wi-Fi networks. In claim 9,
The step of calculating the bandwidth of the VAP is,
The bit rate is calculated using the slope (λ) of Equation 10 derived through the Lagrange multiplier method, the calculated bit rate is quantized, and the quantized bit rate and the most Select an approximate value and calculate the bandwidth of the virtual AP (ACCESS POINT) of each UE (USER ENTITY) using Equation 11,

In equation 10, is the bitrate selected by the ith UE for streaming, represents the Peak Signal-to-Noise Ratio (PSNR) coefficient of the video segment requested by the ith UE, i is a random natural number, and N represents the set of UEs,
In equation 11, is the integrated bandwidth, M is the set of APs, is the segment ratio that the ith UE receives through the jth AP, i is a random natural number, and represents the bandwidth that the i-th UE receives through the j-th AP, respectively.
A cooperative HTTP adaptive streaming method over SDN-based multiple Wi-Fi networks. delete delete In claim 10,
Further comprising: increasing the proportion of all APs receiving segments for each UE by a certain amount if available network resources remain for all APs,
A cooperative HTTP adaptive streaming method over SDN-based multiple Wi-Fi networks. delete delete delete In claim 10,
If the congestion occurs and the sum of time slots used by the UEs is greater than each AP timeslot, initializing the ratio of each UE to share segments and the slope of the segment ratio of each UE,
In the initialization step, the slope value is set to the middle value between the lower slope value and the upper slope limit value to set the initial value, and the previous slope value is initialized as the upper slope value to be used to determine the algorithm termination condition, where The segment sharing ratio is initialized to a value of 1 for the AP that provides the strongest RSSI signal strength among all the APs.
A cooperative HTTP adaptive streaming method over SDN-based multiple Wi-Fi networks. In claim 10,
In the VAP, when the slope is expressed by Equation 8 and Equation 9, it further includes the step of obtaining the bit rate of each UE by adjusting the slope using the relationship between the bit rate and slope expressed by Equation 10. do,
Adjusting the slope includes finding bitrate values that satisfy constraints using binary search,

In Equation 8, L is the Lagrange multiplier (Lagrange mlutiplier), and the coefficient and has different values depending on the type, bit rate, and segment index of the video requested by the UE (USER ENTITY), and is determined by curve fitting the PSNR value of the actual video segment. represents the video bitrate of the segment provided to the ith UE, respectively.
A cooperative HTTP adaptive streaming method over SDN-based multiple Wi-Fi networks. In claim 18,
By setting all APs for each UE to one VAP, the integrated bandwidth of UEs and APs at each AP is defined as Equation 11 in consideration of the usage ratio between UEs and AP. SDN-based multiple Wi-Fi network A collaborative HTTP adaptive streaming method via. A computer-readable recording medium for implementing a program of the cooperative HTTP adaptive streaming method over an SDN-based multiple Wi-Fi network of any one of claims 9, 10, 13, and 17 to 19.

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