WO2020024459A1

WO2020024459A1 - Video live broadcast system based on double-layer drive interference coordination, and implementation method therefor

Info

Publication number: WO2020024459A1
Application number: PCT/CN2018/111789
Authority: WO
Inventors: 田峰; 凌海涛; 陈建新; 周亮; 杨震
Original assignee: 南京邮电大学
Priority date: 2018-08-01
Filing date: 2018-10-25
Publication date: 2020-02-06
Also published as: JP2021500826A; CN108989829A; JP7008998B2

Abstract

Disclosed are a video live broadcast system based on double-layer drive interference coordination, and an implementation method therefor. A sensing node periodically collects frequency spectrum information of a nearby wireless environment and sends the latest data information to an information fusion center FC; the information fusion center FC performs data fusion, resource allocation, resource optimization and the like after receiving the sensing data; after a service is completed, the information fusion center FC releases corresponding resources. In the present invention, before video live broadcast, frequency spectrum energy is detected on a physical layer by using cognitive radio technology, frequency spectrum data is analyzed to identify the frequency spectrum state, and interference is avoided by scheduling; in the video live broadcast process, the frequency spectrum state is determined according to the QoE performance, spectrum resource reallocation is carried out, and cross-layer interference coordination is carried out, thereby realizing the effects of zero interference and low bit errors, and finally realizing video live broadcast having low time delay and high rate.

Description

Video live broadcast system based on double-layer drive interference coordination and implementation method thereof

Technical field

The invention belongs to software wireless information transmission technology, and particularly relates to a video live broadcast system based on double-layer drive interference coordination and an implementation method thereof.

Background technique

Live video is the most popular form of multimedia in recent years. The difference between live video streaming and traditional video transmission is that live video streaming requires high real-time performance. It is a kind of online multimedia transmission that broadcasts at the same time (simultaneous download and simultaneous playback), instead of downloading the complete video resource (offline) and playing it. Therefore, live video transmission requires a transmission network capable of providing a high-speed, low-latency, and low-error broadband transmission environment. However, more and more young people watch live video on mobile clients such as mobile phones, which are often affected by various interferences. In such a transmission environment, the high-performance transmission requirements required for live video streaming are often difficult to meet. Therefore, the problem of transmission interference must be effectively resolved.

Cognitive radio technology achieves interference coordination by making full use of idle spectrum in time and space, thereby reducing the possibility of interference during transmission. Cognitive radio is an intelligent spectrum sharing technology that can perceive the surrounding wireless environment, and through analysis of environmental data, it can obtain a spectrum that meets the requirements, thereby realizing the rational use of spectrum resources. Therefore, in a complex transmission environment, using cognitive radio technology to select an idle spectrum for live video use can effectively solve the interference problem of transmission.

Quality of Experience (QoE) refers to the subjective experience of users on the quality and performance of devices, networks and systems, applications or services, and it is the degree of difficulty for users to complete the entire process. Due to the real-time nature of the live video, some parameters measured can reflect to some extent whether the user's QoE and live broadcast of the live video are strongly interfered.

Software Defined Radio (SDR) is a technology commonly used to study and test communication technologies such as cognitive radio. Software radio technology refers to the use of a universal, standard, modular, fixed hardware platform to implement various radio communication functions (such as operating frequency bands, modulation and demodulation types, data formats, communication protocols, etc.) through software programming. And a radio system that realizes a flexible communication system and communication functions through software reconfiguration. USRP RIO is one of the more mature software radio platforms in recent years. Compared with other instruments of the same type, it has better hardware processing capabilities, convenient operation, and visualized graphic language. At the same time, its adjustable hardware parameters are more extensive and the values are more accurate.

A home base station is a physical device similar to a small base station, and is often used to extend the coverage of mobile communication signals. By placing and enabling home base stations indoors, users can receive high-quality signals indoors. However, after the introduction of home base stations, several kinds of interference have appeared in the working environment of home base stations and base stations: interference between macro cell base stations and home base stations, interference between macro cell base stations and home base station users, and macro cell users and home base stations. Interference between macro cellular users and home base station users, and interference between home base stations and home base stations. These interferences will have a more serious impact on the normal operation of the home base station.

That is to say, the traditional interference coordination after using cognitive radio technology is usually limited to studying how to improve the perception accuracy and perception accuracy. However, once a perception error occurs and an unexpected channel spectrum resource is used, which causes the degradation of communication service quality, the traditional method cannot correct the error in a timely manner. For services such as live video, once such an error occurs, the live video will be affected, and in the worst case, the data stream of the live video will be interrupted.

Therefore, we consider establishing a home base station system test environment based on the USRP and RIO software radio platform to verify the performance of the video live broadcast technology based on double-layer drive interference coordination.

Summary of the invention

Object of the invention: The purpose of the present invention is to solve the deficiencies in the prior art, and provide a video live broadcast system based on double-layer drive interference coordination and its implementation method. The present invention uses the USRP RIO software radio platform as an experimental platform to build a home base station Test and verify the performance of dual-layer drive interference coordinated live video technology. Before live video, use cognitive radio technology to detect spectrum energy on the physical layer, analyze data of the same spectrum provided by different sensing nodes to identify the spectrum state, and avoid interference; Then in the process of live video streaming, the spectrum resource reallocation is determined based on the QoE performance. Through cross-layer interference coordination, the effect of zero interference and low bit error is achieved, and a low-latency, high-rate live video is finally obtained.

Technical solution: A dual-layer drive interference coordination-based live video system of the present invention includes several user modules, a home base station FAP, an information fusion center FC, and a user's corresponding sensing node; wherein the user module refers to a specific user's use Smart mobile devices (such as mobile phones and IPads), and have the function of sending and receiving data; the FAP of the home base station provides network access functions within a limited range. Users access the network through FAP to obtain low-latency, high-rate wireless network services; wireless communication is used between the home base station FAP and the user, and wired communication is used between the home base station FAP and the information fusion center FC, and wired communication can guarantee both The communication between them is efficient and non-interfering; the sensing node senses the nearby wireless environment information and saves the sensed information to the downloaded functional node, and also has the function of sending data; the wired connection is used between the sensing node and the information fusion center FC Data exchange; the information fusion center FC uniformly manages all the home base stations, sensing nodes, and the wireless environment information collected by the sensing nodes: by analyzing the wireless environment data information, the spectrum resources and unavailable services can be obtained Provide spectrum resources for services; once a user needs to use spectrum resources, the information fusion center FC selects and allocates corresponding resources from the available spectrum resources for use by the home base station FAP and users. Through the above-mentioned centralized management of wireless resources, interference coordination is effectively performed.

Among them, the sensing node refers to a functional node that senses nearby wireless environment information and saves the sensed information.

The invention also discloses a method for realizing live video broadcasting based on double-layer drive interference coordination, which includes the following steps:

Step 1: The sensing node periodically collects the spectrum information of the nearby wireless environment and sends the latest data information to the information fusion center FC. Because the number of sensing nodes is large and the span of the sensing spectrum information is large, it is necessary to The sent data is encapsulated according to the corresponding data format.

Step 2: After receiving the sensing data, the information fusion center FC uses the fusion strategy to obtain a list of available spectrum resources; when a user requests access, the information fusion center FC allocates corresponding spectrum resources (for example, free spectrum can provide a spectrum with good communication quality) ) For use by the user and the home base station FAP; if no suitable resources are available, a message is returned to the home base station FAP and the user requests to enter the waiting service queue. Once there are free resources, the user in the waiting service queue is preferentially allocated resources; At the time of resource allocation, the information fusion center FC records the spectrum usage. The next time a user requests access, the usage records are compared to prevent users from repeating network access or spectrum resource reuse.

Step 3: While users occupy spectrum resources, they need to feed back a series of user experience quality parameters (such as bit error rate and rate), and then monitor and analyze these user experience quality QoE to decide whether to reallocate spectrum resources; if the user experience quality The QoE is lower than the service requirement, and the information fusion center FC re-allocates an available spectrum resource to the user and the corresponding home base station FAP;

Step 4: After the service ends, the information fusion center FC releases the corresponding resources.

In the above-mentioned method for realizing live video based on double-layer drive interference coordination, prior to live video, cognitive radio technology is used at the physical layer to select an idle channel to transmit data; and to sense the surrounding wireless environment to collect spectrum data in the wireless environment; Analyze the spectrum energy data perceived by different sensing nodes of the same spectrum, and select idle channels for live video data transmission. During the live video process, the QoE performance is periodically detected at the application layer. Once the QoE performance is lower than the preset value, reallocation The new spectrum resources ensure that users are not affected by interference during the use of communication services, improve the stability of information transmission, and ensure the quality of video and the fluency of live video.

Therefore, in step 3, the QoE performance needs to be periodically detected and discriminated, so that similar perception errors can be found in time and the remaining alternative idle channels can be selected for data communication.

Further, the specific process of the fusion strategy in step 2 is:

When the information fusion center FC receives the data from each sensing node, it first performs a sampling process on all the data, and the sampling rate is M (the size of M depends on the system performance). After the sampling process is completed, for different sensing nodes The capacity detection data of the same frequency band takes the average value K _i , where i represents different sensing nodes, and the following hard decision formula is used to determine whether the spectrum is free:

Among them, N is the number of sensing nodes, H ₀ and H ₁ are hard decision thresholds for judging free resources and non-idle resources, respectively, and F is the decision result;

When the decision result F = 0, the spectrum resource is an idle resource; when the decision result F = 1, the spectrum resource is a non-idle resource; when the decision result F = 2, the spectrum resource is a resource that cannot be accurately defined, then Make a second judgment;

For the method of secondary judgment, a voting mechanism is adopted, that is, the number of all K _i <H ₀ or K _i > H ₁ is counted. When the number of votes of the sensing node exceeds half, (that is, if all the sensing nodes submit data, if (More than half of the node data is considered idle or non-idle), and it is judged as an idle or non-idle resource. If the result of the second decision cannot be obtained, it will be discarded in this round of decision and wait for the next round of new decision Judge again.

Further, when the fusion strategy in step 2 runs in the system, it runs at a certain period of time, and the time period is closely related to the pros and cons of the system's sensing function. The operation period of the fusion strategy is set to an adjustable The parameters are modified in real time during subsequent debugging and use; the theoretical time cost of the fusion strategy is O (n), so the setting of the cycle period only needs to ensure that the fusion process can be completed.

Further, the process of reallocating spectrum resources in step 3 is the resource optimization phase. The specific operation mode is: first monitor and analyze the QoE detection of the user experience quality. If the user experience quality is lower than a preset threshold (here The threshold value depends on the specific service used by the user. For example, the threshold value can be set to 0, that is, once an error occurs, the spectrum resource is considered bad and a new spectrum resource needs to be replaced.) When the information fusion center FC refers to the allocated resource, The saved user resource correspondence table determines whether a type A event or a type B event occurs: If a type A event occurs, it indicates that the two communication links within the FAP service range of the home base station interfere with each other, causing the quality of user experience QoE to decrease, and the information is fused The central FC re-allocates resources for the user who has occupied the channel for a short period of time; if a Type B event occurs, it indicates that the channel occupied by this user has been interfered by the macro cell base station, macro cell users, or other interference, causing the user's quality of experience to decrease. Convergence Center FC reallocates spectrum resources for users;

The above-mentioned Type A events and Type B events indicate different interference situations, respectively. Type A events refer to the mutual interference between different home base stations FAP and users; Type B events refer to the communication occupation of macro base stations and macro base station users. Channels or strong interference cause interference to FAP users at home base stations.

Beneficial effects: The present invention is suitable for indoor environments. Using the USRP RIO platform and LabView, a series of system designs and experiments have been carried out, which effectively verifies that this solution can realize live video broadcast and use spectrum resources effectively in an indoor environment. To improve spectrum utilization and optimize interference coordination. Juyi includes the following advantages:

(1) A zero-interference, low-error video live broadcast is realized. Double-layer drive interference coordination technology achieves cross-layer interference coordination at both the physical and application layers. Before the live video broadcast, the spectrum channels are screened and interference-free channels are selected for data communication. During the live video broadcast, QoE performance is periodically checked, and when QoE is severely degraded, spectrum resources are re-allocated. Therefore, both the transmission channel selected before the live video broadcast and the transmission channel used in the live video broadcast can guarantee the effect of no interference and low bit error.

(2) The transmission rate is high. Because the data communication is performed in the interference-free channel, the transmission rate is high and the data obtained in the actual system test and theoretical calculation data are very close.

(3) The system responds quickly with low latency. In the test system, when the user and the home base station need to switch the service channel resources, it takes a certain amount of time to complete this process. From the moment when the QoE performance of the user experience is severely degraded until the channel change is completed, the time overhead of the entire process is mainly divided into the following types: system inherent time overhead, selection and distribution of spectrum resource information. After the actual system measurement, in order to reconfigure and use the new RF information, the inherent time overhead of the system is about 30ms. This time overhead is related to the actual hardware used. The theoretical time complexity of the process of selecting and distributing spectrum resource information is O (1), and the time required in the system is much lower than 1ms. Therefore, it can be seen that the time overhead of the entire response process is 30ms, and this time is related to the hardware performance, which shows that the system responds quickly. At the same time, when the video is transmitted, the quality of the user experience will be reduced, which will cause the video to freeze or display. In this case, the 30ms time overhead of switching service channel resources is tolerable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system frame diagram of the present invention;

FIG. 2 is a flowchart for implementing the present invention;

FIG. 3 is a data encapsulation diagram in the present invention;

4 is a diagram of a resource optimization stage of the present invention;

5 is an experimental deployment diagram in the embodiment;

FIG. 6 is a functional diagram of a sensing node according to the present invention;

FIG. 7 is a simplified function diagram of a user terminal of the present invention;

FIG. 8 is a functional diagram of a home base station according to the present invention; FIG.

FIG. 9 is a functional diagram of an information fusion center of the present invention;

FIG. 10 is a diagram of setting radio frequency parameters of a user terminal in an embodiment; FIG.

11 is a diagram of setting radio frequency parameters of a home base station in an embodiment;

FIG. 12 is a screenshot of a video playback on the sending end in the embodiment; FIG.

FIG. 13 is a screenshot of a video playback on the receiving end in the embodiment; FIG.

FIG. 14 is a constellation diagram of normal transmission video data in the embodiment; FIG.

15 is a bit error rate of normal transmission in the embodiment;

16 is an energy spectrum when transmitting video data in the embodiment;

FIG. 17 is a diagram of adjusted user-end radio frequency parameters in the embodiment; FIG.

FIG. 18 is a diagram of an adjusted radio frequency parameter of the home base station in the embodiment; FIG.

FIG. 19 is an adjusted constellation diagram in the embodiment.

detailed description

The technical solution of the present invention is described in detail below, but the protection scope of the present invention is not limited to the embodiments.

As shown in FIG. 1, a dual-layer drive interference coordination-based video live broadcast system of the present invention includes several user modules, a home base station FAP, an information fusion center FC, and a user's corresponding sensing node; wherein the user module refers to a specific user The smart mobile device used (such as a smart mobile phone, IPad, etc.), and has the function of sending and receiving data; the home base station FAP provides a network access function within a limited range. Users access the network through FAP to obtain low-latency, high-rate wireless network services; wireless communication is used between the home base station FAP and the user, and wired communication is used between the home base station FAP and the information fusion center FC, and wired communication can guarantee both Efficient and non-interference communication between the sensing nodes; the sensing node senses the nearby wireless environment information and saves the downloaded functional nodes, and also has the function of sending data; the sensing nodes and the information fusion center FC use a wired connection for data exchange ; Information fusion center FC unified management of all home base stations, sensing nodes, and wireless environment information collected by sensing nodes: By analyzing wireless environment data information, we can obtain spectrum resources that can provide services and spectrum resources that cannot provide services; when Once a user needs to use spectrum resources, the information fusion center FC selects and allocates corresponding resources from the spectrum resources that can provide services for use by the home base station FAP and users. Through the above-mentioned centralized management of wireless resources, interference coordination is effectively performed.

As shown in FIG. 2, a method for implementing live video broadcasting based on two-layer drive interference coordination of the present invention includes the following steps:

Step 1: The sensing node periodically collects the spectrum information of the nearby wireless environment and sends the latest data information to the information fusion center FC. Because the number of sensing nodes is large and the span of the sensing spectrum information is large, it is necessary to The sent data is encapsulated according to a certain data format. For example, the encapsulation format is shown in Figure 3 of the description.

Step 2: After receiving the sensing data, the information fusion center FC uses the fusion strategy to obtain a list of available spectrum resources; when a user requests access, the information fusion center FC allocates appropriate spectrum resources for use by the user and the home base station FAP; if not suitable If the available resources are available, a message is returned to the home base station FAP and the user requests to enter the waiting service queue. Once there are free resources, the users in the waiting service queue are preferentially allocated resources; while the resources are allocated, the information fusion center FC records the spectrum usage. In the case, the next time the user requests access, the usage records are compared to avoid repeated user access to the network or repeated use of spectrum resources;

As shown in Figure 4, the QoE detection of user experience quality is first monitored and analyzed. If the user experience quality is lower than a preset threshold, the information fusion center FC refers to the user resource correspondence table saved when allocating resources to determine whether a type A event has occurred Or type B event: If a type A event occurs, it indicates that the two communication links in the FAP service area of the home base station interfere with each other, causing a decrease in the quality of user experience QoE, and the information fusion center FC reallocates resources for users who occupy a shorter channel time. If a Type B event occurs, it indicates that the channel occupied by this user has been interfered by a macro cell base station, macro cell user, or other interference, causing the QoE of the user experience quality to decline, and the information fusion center FC re-allocates spectrum resources for the user; as mentioned above Type A events and Type B events indicate different interference conditions, respectively. Type A events refer to the mutual interference caused by the communication between different home base stations FAP and users; Type B events refer to the communication channels occupied or The situation where FAP users of home base stations are interfered by interference;

The above implementation method mainly includes two processes of a fusion strategy and a scheduling strategy.

A. Convergence strategy

When the information fusion center receives the data from each sensing node, it first samples all the data once, and the sampling rate is M (the size of M depends on the system performance). After the sampling process is completed, the average value of the capacity detection data of the same frequency band for different sensing nodes is K _i , where i represents different sensing nodes, and the following hard decision formula is used to determine whether the spectrum is free:

Among them, N is the number of sensing nodes, H ₀ and H ₁ are hard decision thresholds for judging free resources and non-idle resources, respectively, and F is the decision result.

When the decision result F = 0, the spectrum resource is an idle resource; when the decision result F = 1, the spectrum resource is a non-idle resource; when the decision result F = 2, the spectrum resource is a resource that cannot be accurately defined, then Make a second judgment; for the method of second judgment, a voting mechanism is adopted, that is, the number of all K _i <H ₀ or K _i > H ₁ is counted. When the number of votes exceeds half, it is judged as an idle or non-idle resource. If the result of the second decision cannot obtain the resources, it will be discarded in this round of decision, and the decision will be made again when the next round of new decision is initiated.

When the fusion strategy runs in the system, it runs in a certain period of time. This time period is closely related to the pros and cons of the system's sensing function. The running period of the fusion strategy is set as an adjustable parameter, which can be modified in real time during subsequent commissioning and use. The theoretical time cost of the fusion strategy is O (n), so the setting of the cycle period only needs to ensure that the fusion process can be completed.

B. Scheduling strategy

The scheduling strategy is divided into two parts: the resource allocation phase and the resource optimization phase. During the resource allocation phase, the system quickly allocates available resources to new network users so that they can get available resources in the shortest possible time. In the resource optimization stage, the system analyzes a series of user experience quality parameters fed back from the resources obtained by the user. If the user experience quality is not satisfactory, the system will adjust the allocated resources to improve the user experience quality.

The complete steps of the scheduling strategy are as follows:

(a) When a user enters the network, the system is requested to allocate resources for the first time, and the resource allocation phase is entered. During this phase, the system randomly selects an available spectrum resource from the available spectrum resources to allocate to the user, ensuring that the user obtains the available resource in the shortest time and starts transmitting data. At the same time, the information fusion center saves the allocated resource information and corresponding user information in the user resource correspondence table, which is convenient for managing spectrum resources.

(b) After the user obtains the available spectrum resources, the resource allocation phase is completed and the resource optimization phase is entered. The continuous scope of the optimization phase is the entire process of using resources by the user. When the user exits the network, the optimization phase is terminated and the service is exited. The entire resource optimization stage is driven by the quality of user experience QoE, and the service is tested according to a certain period of time (adjusted according to the actual environment and needs). When the user experience quality QoE index is lower than a preset threshold (set according to service requirements), the system adjusts the user and the spectrum resources used by it, and allocates other available spectrum resources to it.

Example:

1.Experimental platform

In software radio, except for the basic frequency conversion, A / D, D / A conversion, and RF drive, which are implemented by the hardware platform USRP, RIO, and 2943R, the remaining functions are all designed by software. Except for the basic receiving and sending functions, almost all the extended functions of the entire communication process need to be designed and programmed by themselves.

A series of physical parameters of NI USRP and RIO 2943R are as follows: adjustable frequency range is 1.2GHz ~ 6GHz, real-time bandwidth is 40MHz, PCIex4 bus speed is 800MB / s, Kintex7 FPGA chip.

The software part of the experiment is designed and debugged using Labview2015. On the basis of the RF transceiver driver provided by the software itself, a series of functions required by the present invention are extended, thereby realizing the entire invention.

2. Experimental environment settings

The experimental arrangement is shown in Figure 5, which is specifically deployed in the test system. In the experimental environment, two users and corresponding home base stations, an information fusion center and several sensing nodes were set up. During the experiment, two users can be interference sources between each other, so there is no need to set extra human interference items.

The communication method between the user and the home base station is wireless communication; the communication method between the home base station and the information fusion center is wired communication, which uses optical fiber connection; the sensing node and the information fusion center are also connected through optical fiber. This setting mode ensures the reliability of all communication on the system side, and has the ability to effectively test the actual effect of the user during use.

This embodiment mainly includes three parts: an information fusion center, a user and a home base station, and a sensing node.

The program setting of the sensing node is relatively simple. In order to reduce the deployment difficulty of the sensing node, it only needs to sense the data of the surrounding wireless environment and send the data to the information fusion center. Because the USRP platform can only perceive data in a smaller bandwidth at the same time, it is necessary to add a frequency sweep function to it, and sequentially scan the data on each spectrum within the set bandwidth. The schematic diagram of the specific sensor node function program is shown in Figure 6. After inputting the set parameters of the radio frequency transmission and reception data, the program is started, and the sensing data is started, and then the sensed data is encapsulated according to the data format of FIG. 3, and then transmitted to the information fusion center through UDP. Under the control of the frequency sweep function module, the above sensing process is performed on different frequency bands without gaps. After completing the task of the preset sensing range, restart the next sensing task. Because the range of 1.2GHz to 6GHz is too large, it is not beneficial to debug and observe the results during the experiment. Therefore, in this embodiment, during the test, several frequency bands of 2.2GHz to 2.8GHz are selected for testing, which speeds up the experiment speed and ensures the experiment. Reliability of results.

User and home base station experimental setup:

Because the user and the home base station are mainly responsible for data communication in the experiment, transmitting video and displaying the transmission results and statistical data, using the USRP RIO device can configure the characteristics of two single antenna users, and configure the user and the home base station in On the same USRP RIO device. Although physically located on the same device, the data communication between the two is done through a wireless channel, which can effectively test the function of wirelessly transmitting video. Taking the user sending data to the home base station as an example, FIG. 7 is a functional diagram of the user terminal, and FIG. 8 is a functional diagram of the home base station.

It can be known from FIG. 7 that at the user end, starting from the source, after the operations such as QAM modulation, inserting a guard interval, framing, etc., it is sent to the wireless channel by the RF sending module. There is an external expansion interface in the RF transmission module, which can be called by the module that modifies the transmission parameters. It can modify the transmitted RF parameters in real time, such as the transmitted center frequency, local oscillator, and gain. Because the system test uses video data, the source is the data packet processed by VLC software.

As can be seen from FIG. 8, in the home base station, the function is mainly divided into two parts: exchanging data with the user and exchanging data with the information fusion center. Exchanging data with users, taking receiving data as an example. After receiving wireless information from the antenna, it passes through the RF receiving module, performs frame synchronization, frame analysis, channel equalization, and QAM demodulation, and finally arrives at the sink. The destination is VLC software. After the data is obtained, VLC is internally decoded, and the playback quality can be observed at the same time.

Experimental setting of Information Fusion Center:

For the information fusion center, the functions to be completed include the integration strategy, the monitoring and adjustment of the quality of user experience, and the management and allocation of spectrum resources. In the experimental test, an independent information fusion center was set up for testing.

Figure 9 is a simplified functional diagram of the information fusion center. The UDP receiving module of the information fusion center needs to receive two parts of data, which are the data sent by the home base station and the data sent by the sensing node. Therefore, when receiving data from different sources, the data processing modules are different. When receiving data from the home base station, the data enters the user experience quality monitoring module to determine whether it meets the quality of service requirements. If it does not meet the requirements, then the storage module selects new available spectrum resources and notifies the home base station to change the spectrum resources through the UDP sending module. . When the data from the sensing node is received, the data enters the fusion strategy module. After data processing, the available spectrum resource group is obtained and stored in the storage module for use. Different data sources use different UDP port numbers for UDP communication, so different data sources can be easily identified.

3. Experimental process

Step 1) Configure preset parameters. Before starting all programs, a series of preset parameters need to be set. The initial radio frequency parameters of the user and the home base station and the radio frequency parameter settings of the sensing node are as shown in FIG. 10 and FIG. 11. Figure 10 shows the RF parameter settings at the user end. The initial center frequency is 2.4GHz, the local oscillator frequency is -1Hz, and the transmission gain is 0dBm. Figure 11 shows the corresponding RF parameter settings of the home base station. The center frequency of the receiving frequency is 2.4 GHz. The local oscillator frequency is -1Hz and the receive gain is 0dBm.

Step 2) Run the program and start data communication. Then open the VLC script file and start generating video source data and playing the received video source data. The transmitted and received video images are shown in FIG. 12 and FIG. 13. FIG. 14 is a constellation diagram at the receiving end. It can be seen that the modulation mode of BPSK is used but the constellation diagram is clear. Fig. 15 is a graph of average bit error rate and time. In the process of stable transmission, the bit error rate is almost zero. Figure 16 is the frequency energy spectrum when transmitting video data. It can be clearly seen that the center frequency is the midpoint, each side occupies half the bandwidth, and a total transmission bandwidth of 3MHz.

Step 3) Manually change the frequency band used by one of the users, so that two users transmit data in the same frequency band, causing interference. Test whether the scheduling strategy in the system is functioning properly.

Step 4) The system re-allocates new resources to the users who have interfered, and the video transmission returns to normal. Figures 17 and 18 show that after artificially adding interference, one of the users and the home base station adjusted the frequency of use under the control of the scheduling strategy, and the adjusted center occupied frequency was 2.7 GHz. FIG. 19 is a constellation diagram of a user and a home base station occupying a frequency of 2.7 GHz.

During the experiment, through theoretical analysis and calculations, there are the following calculation formulas: The data length of a frame is (1 + 1 + 706) × (16 + 64) = 56640Samples, which contains the LTF sequence, SIG sequence and data, and the interval length is The data length is 64. Among them, the actual data is 706 × 64 = 45184bit, the rate is 45184bit ÷ 16ms / 1s = 2.824M / s, and the transmission rate is 56640 ÷ 16ms / 1s = 3.54M / s. When data communication is performed in an interference-free channel, the transmission rate of the present invention is higher. According to the above embodiments, it can be further seen that the present invention screens spectrum channels and selects interference-free channels for data communication before performing live video. During the live video process, the QoE performance is periodically detected, and it is restarted when QoE drops severely Allocate spectrum resources. Therefore, both the transmission channel selected before the live video broadcast and the transmission channel used in the live video broadcast can guarantee its interference-free, low error rate and high transmission rate.

Claims

A video live broadcast system based on two-layer drive interference coordination, which is characterized in that it includes several user modules, a home base station FAP, an information fusion center FC, and a user's corresponding sensing node;

The user module refers to a smart mobile device used by a specific user and has a function of sending and receiving data;

The home base station FAP provides network access, and the user accesses the network through the home base station FAP. The home base station FAP and the user use wireless communication, and the home base station FAP and the information fusion center FC use wired communication.

The sensing node senses the nearby wireless environment information and saves the sensed information to the downloaded functional node, and at the same time, the sensing node sends data to the information fusion center FC; the sensing node and the information fusion center FC use a wired connection for data exchange. ;

The information fusion center FC uniformly manages all the home base stations, sensing nodes, and wireless environment information collected by the sensing nodes: by analyzing the wireless environment data information, spectrum resources that can provide services and spectrum resources that cannot provide services are obtained; When a user needs to use spectrum resources, the information fusion center FC selects and allocates corresponding resources from the spectrum resources that can provide services for use by the home base station FAP and users.
A method for realizing video live broadcast based on two-layer drive interference coordination, which is characterized by including the following steps:

Step 1: The sensing node periodically collects the spectrum information of the nearby wireless environment and sends the latest data information to the information fusion center FC; and before sending the information, encapsulates the sent data according to the corresponding data format;

Step 2: After receiving the sensing data, the information fusion center FC uses the fusion strategy to obtain a list of available spectrum resources; when a user requests access, the information fusion center FC allocates corresponding spectrum resources for use by the user and the home base station FAP; if there is no suitable If the resource is available, a message is returned to the FAP of the home base station and the user requests to enter the waiting service queue. Once there are free resources, the user in the waiting service queue is preferentially allocated resources; while the resources are allocated, the information fusion center FC records the spectrum usage In the next user request for access, compare usage records to prevent users from repeatedly accessing the network or reusing spectrum resources;

Step 3: The user needs to feed back the corresponding user experience quality parameters while occupying spectrum resources, and then monitors and analyzes the user experience quality QoE before deciding whether to reallocate the spectrum resources: If the user experience quality QoE is lower than the service demand, the information fusion center FC re- Allocate an available spectrum resource to the user and the corresponding home base station FAP;

Step 4: After the service ends, the information fusion center FC releases the corresponding spectrum resources.
The method for implementing live video broadcasting based on double-layer drive interference coordination according to claim 2, characterized in that the specific process of the fusion strategy in step 2 is:

When the information fusion center FC receives the data from each sensing node, it first samples all the data once, and the sampling rate is M. After the sampling processing is completed, the average value of the capacity detection data of the same frequency band for different sensing nodes is taken as K i , I represents different sensing nodes, and determines whether the spectrum is free by the following hard decision formula:

Among them, N is the number of sensing nodes, H 0 and H 1 are hard decision thresholds for judging free resources and non-idle resources, respectively, and F is the decision result;

When the decision result F = 0, the spectrum resource is an idle resource; when the decision result F = 1, the spectrum resource is a non-idle resource; when the decision result F = 2, the spectrum resource is a resource that cannot be accurately defined, then Make a second judgment;

The voting mechanism is used for the second decision, that is, the total number of K i <H 0 or K i > H 1 is counted. When the number of votes of the sensing node exceeds half, it is judged as an idle or non-idle resource. The resources that cannot be obtained are discarded in this round of decision, and a decision is made again when the next round of new decision is initiated.
The method for implementing live video broadcasting based on double-layer drive interference coordination according to claim 2, characterized in that: the fusion strategy in step 2 runs in a corresponding cycle in the system, and the operating cycle of the fusion strategy is set to an adjustable The parameters are modified in real time during subsequent debugging and use; the theoretical time overhead of the fusion strategy is O (n).
The method for implementing live video broadcasting based on double-layer drive interference coordination according to claim 2, characterized in that the process of reallocating spectrum resources in step 3 is a resource optimization phase, and the specific operation mode is:

First, monitor and analyze the QoE detection of user experience quality. If the user experience quality is lower than the preset threshold, the information fusion center FC refers to the user resource correspondence table saved when allocating resources to determine whether a type A event or a type B event has occurred: If The occurrence of a type A event indicates that the two communication links within the FAP service area of the home base station interfere with each other, causing the QoE of the user experience quality to decline, and the information fusion center FC reallocates resources for users who occupy a shorter channel time; if a type B event occurs , It means that the channel occupied by this user has been interfered by a macro cell base station, a macro cell user, or other interference, resulting in a decrease in the QoE of the user experience quality, and the information fusion center FC reallocates spectrum resources for the user;

The above-mentioned Type A events and Type B events indicate different interference situations, respectively. Type A events refer to the mutual interference between different home base stations FAP and users; Type B events refer to the communication occupation of macro base stations and macro base station users. Channels or strong interference cause interference to FAP users at home base stations.