JP7008998B2 - Live video broadcasting system based on two-layer drive interference coordination and its realization method - Google Patents

Description

The present invention belongs to software defined radio information transmission technology, and specifically relates to a live video broadcasting system based on two-layer drive interference coordination and a method for realizing the same.

In recent years, live video broadcasting has become the most popular multimedia format. The distinction between live video broadcasts and traditional video transmissions is that live video broadcasts require high real-time performance, rather than playing back (offline) after the complete video resource has been downloaded. It is an online multimedia transmission that plays while downloading (plays at the same time as downloading). Therefore, in live video broadcasting, it is necessary to be able to provide a broadband transmission environment with high speed, low delay, and low bit error rate by a transmission network. However, as more and more young people watch live video broadcasts on mobile clients such as mobile phones, they are often affected by various types of interference. In such a transmission environment, it is often difficult to meet the high-performance transmission requirements required for live video broadcasting. Therefore, the problem of transmission interference must be effectively solved.

Cognitive radio technology makes full use of the free spectrum in time and space to achieve interference coordination, thereby reducing the possibility of interference during transmission. Cognitive radio is a smart spectrum sharing technology that can sense the surrounding radio environment and analyze the environmental data to obtain a spectrum that meets the requirements, and also realizes rational use of spectrum resources. .. Therefore, in a complicated transmission environment, the problem of transmission interference can be effectively solved by selecting an empty spectrum for live video broadcasting using cognitive radio technology.

User experience quality (Quality of Experience, QoE) refers to the user's subjective experience of the quality and performance of devices, networks and systems, applications and operations, and is the degree of difficulty of completing the entire process felt by the user. Due to the real-time nature of live video broadcasting, some of the measured parameters may reflect to some extent the QoE when the user uses live video broadcasting and whether the live video broadcasting is strongly interfered with. can.

Software defined radio (SDR) is one of the technical means often used for research and testing of communication technologies such as cognitive radio. Software defined radio technology employs general-purpose, standard and modular, fixed and immutable hardware platforms to program various wireless communication functions (eg, operating frequency band, modulation / demodulation type, data format, communication protocol, etc.). It refers to the realization of a method and the realization of a flexible and diverse communication system and wireless system with communication functions by software refactoring. USRP RIO is one of the relatively mature software defined radio platforms in recent years, with advantages such as better hardware processing power, convenient operation, and visualization graphic language compared to other devices of the same type. Its adjustable hardware parameters are wider and the numbers are more accurate.

Home base stations are physical devices that resemble small base stations and are often used to extend the coverage of mobile communication signals. If the home base station is placed indoors and enabled, the user can receive high quality signals even indoors. However, after the introduction of the home base station, the operating environment of the home base station and the base station includes interference between the macrocell base station and the home base station, interference between the macrocell base station and the user of the home base station, and macrocell. New interferences are emerging, such as interference between the user and the home base station, interference between the macrocell user and the home base station user, and interference between the home base station and the home base station. These interferences have a serious impact on a home base station that is operating normally.

That is, conventional coherence coordination after the use of cognitive radio technology is usually limited to studies of how to improve sensing accuracy and sensing accuracy. However, if the quality of the communication service deteriorates due to the detection of the occurrence of an error and the use of unintended channel spectrum resources, the error cannot be corrected in a timely manner by the conventional method. For services such as live video broadcasting, when such an error occurs, the live video broadcasting is affected, and in the worst case, the data stream of the live video broadcasting is interrupted.

Therefore, we believe that we will verify the technical performance of live video broadcasting based on two-layer drive interference coordination through a test environment for home base station systems built on the USRP RIO software defined radio platform.

Purpose of the Invention: An object of the present invention is to provide a live video broadcasting system based on two-layer drive interference coordination that solves the shortcomings existing in the prior art, and a method for realizing the same, and the present invention is the USRP RIO software. Using the wireless platform as an experimental platform, a home base station is constructed to test and verify the technical performance of live video broadcasting of two-layer drive interference coordination. Before live video broadcasting, cognitive radio technology is used. Spectral energy is detected in the physical layer, data of the same spectrum provided by different sensing nodes is analyzed to identify the spectral state, avoid interference, and then discriminated by QoE performance during live video broadcasting. Determine resource reallocation, achieve non-interference and low bit error rate effects through cross-layer interference coordination, and finally obtain low-latency, high-speed live video broadcasts.

Technical proposal: The video live broadcasting system based on the two-layer drive interference coordination according to the present invention includes several user modules, a home base station FAP, an information fusion center FC, and a sensing node corresponding to the user, and the above user module. Specifically refers to a smart mobile device (for example, a mobile phone and an IPad) used by a user, and has a data transmission / reception function. The home base station FAP has a network access function within a limited range. The user accesses the network through FAP to obtain low-latency, high-speed wireless network service, and adopts wireless communication between the home base station FAP and the user, and the home base station. Wired communication is adopted between the FAP and the information fusion center FC, and the wired communication can guarantee high efficiency and no interference of communication between the two, and the above-mentioned sensing node senses nearby wireless environment information. It is a functional node that saves the sensed information, and also has a function to send data. The information fusion center is located between the sensing node and the information fusion center FC by adopting a wired connection method to exchange data. FC integrates and manages all home base stations, sensing nodes, and wireless environment information collected by sensing nodes within the service range, and can provide services by analyzing wireless environment data information. If there is a user who has obtained a spectrum resource and a spectrum resource that cannot be serviced and needs to use the spectrum resource, the Information Fusion Center FC will select the corresponding resource from the spectrum resources that can be serviced. Is selected and assigned for use by the home base station FAP and the user. Interference coordination is effectively performed by centrally managing radio resources as described above.

The sensing node refers to a functional node that senses nearby wireless environment information and stores the sensed information.

The present invention further discloses a method for realizing live video broadcasting based on two-layer drive interference coordination, and this method for realizing live video broadcasting includes steps 1 to 4.
Step 1 is a step in which the sensing node periodically collects the spectral information of the nearby wireless environment and transmits the latest data information to the information fusion center FC. The number of sensing nodes is large, and the spectral information is sensed. Due to the large span, the transmitted data must be encapsulated according to the appropriate data format before transmitting the information.
In step 2, after the information fusion center FC receives the sensing data, the fusion strategy is used to obtain a list of available spectral resources, and if there is a user who has requested access, the information fusion center FC determines the corresponding spectral resource. Allocate a free spectrum (eg, a spectrum capable of providing good communication quality) for use by the user and the home base station FAP, and if there is no suitable available resource, send a message to that effect to the home base station FAP. In return, the request of the user is put in the service waiting queue, and when free resources are available, the resources are preferentially allocated to the users in the service waiting queue, and at the same time as the resource allocation, the information fusion center FC records the spectrum usage status. , A step of comparing usage records to avoid duplicate network access or duplicate use of spectral resources by the user the next time the user requests access.
Step 3 requires that the user occupy the spectral resource and at the same time feed back a set of user experience quality parameters (eg, bit error rate, speed, etc.), and then monitor and analyze these user experience quality QoEs. Determines whether to reallocate the spectral resources, and if the user experience quality QoE is lower than the service demand, the Information Fusion Center FC reallocates the available spectral resources to the user and the corresponding home base station FAP. It's a step.
Step 4 is a step in which the information fusion center FC releases the corresponding resource after the service ends.

In the above-mentioned method for realizing live video broadcasting based on two-layer drive interference coordination, data transmission is performed by selecting an empty channel in the physical layer using cognitive wireless technology before performing live video broadcasting, and the surrounding wireless environment is sensed. By doing so, spectrum data in the wireless environment is collected, spectral energy data sensed by different sensing nodes of the same spectrum is analyzed, an empty channel is selected, and data transmission of live video broadcasting is performed, and live video broadcasting is in progress. In addition, the QoE performance is periodically detected in the application layer, and when the QoE performance becomes lower than the preset value, a new spectral resource is reassigned so that the user is not affected by interference while using the communication service. Guarantee, improve the stability of information transmission, guarantee the quality of video and the smoothness of live video broadcasting.

Therefore, in step 3, it is necessary to periodically detect and determine the QoE performance, thereby finding similar detection errors in a timely manner, selecting the remaining free channels as candidates, and performing data communication. be able to.

Ｎは、感知ノードの数であり、Ｈ_０及びＨ_１は、それぞれ空きリソース及び非空きリソースを判断する硬判定閾値であり、Ｆは、判定結果を表し、
判定結果Ｆ＝０の場合、該スペクトルリソースは、空きリソースであり、判定結果Ｆ＝１の場合、該スペクトルリソースは、非空きリソースであり、判定結果Ｆ＝２の場合、該スペクトルリソースは、正確に判断できないリソースとなり、二次判定を行い、
二次判定方式について、投票メカニズムが採用され、即ち、全てのＫ_ｉ＜Ｈ_０又はＫ_ｉ＞Ｈ_１の数を統計し、感知ノードの投票数が半分を超える（即ち、全ての感知ノードから提交されたデータのうち、半分以上のノードデータが空き又は非空きとされる）と、それを空き又は非空きリソースであると判定し、二次判定を経ても結果となるリソースが得られない場合、当意思決定ラウンドでそれを破棄し、次の新しい意思決定ラウンドの開始まで待って判定を再び行う。 Furthermore, as a specific process of the fusion strategy in step 2 above,
When the Information Fusion Center FC receives the data sent from each sensing node, it first performs sampling processing on all the data, sets the sampling rate to M (the magnitude of M is determined by the system performance), and the sampling processing is completed. After that, the average Ki is taken for the capability detection data of the same frequency band of different sensing nodes, _i represents different sensing nodes, and it is judged whether the spectrum is open by the following rigid determination formula.

N is the number of sensing nodes, H ₀ and H ₁ are hard judgment thresholds for judging free resources and non-free resources, respectively, and F represents the judgment result.
When the determination result F = 0, the spectrum resource is a free resource, when the determination result F = 1, the spectrum resource is a non-free resource, and when the determination result F = 2, the spectrum resource is. It becomes a resource that cannot be judged accurately, so a secondary judgment is made and
For the secondary decision method, a voting mechanism is adopted, that is, the number of all _{Ki <H 0 or Ki} > H ₁ is statistic, and the number of votes of the sensing node exceeds half (that is, from all sensing nodes). Of the submitted data, more than half of the node data is free or non-free), it is judged as a free or non-free resource, and the resulting resource cannot be obtained even after the secondary judgment. If so, discard it in this decision round, wait until the start of the next new decision round, and make the decision again.

Further, the fusion strategy in step 2 is executed in the system d at a fixed time cycle, and the time cycle is closely related to the superiority or inferiority of the system sensing function, and the execution cycle of the fusion strategy can be adjusted. Set as a parameter and changed in real time during subsequent debugging and use, the theoretical time overhead of the fusion strategy is O (n), so the cycle cycle setting ensures that the fusion process can be completed. do it.

Further, the process of reallocating the spectrum resource in step 3 is a resource optimization stage, and as a specific operation method, first, the detection of the user experience quality QoE is monitored and analyzed, and if the user experience quality is higher than the preset threshold value. If low (where the threshold is determined by the specific service used by the user, for example the threshold may be set to 0, ie if there is a bit error, the spectral resource is bad and the new spectrum (Need to be replaced with a resource), the Information Fusion Center FC refers to the user resource correspondence table saved at the time of resource allocation, determines whether an A-type event or a B-type event has occurred, and determines whether an A-type event or a B-type event has occurred. When the above occurs, the information fusion center FC determines the channel occupancy time in order to indicate that the two communication links interfere with each other within the service range of the home base station FAP and the user experience quality QoE is deteriorated. When a resource is reassigned to the shorter user and a B-type event occurs, the channel occupied by this user is subject to interference from the macrocell base station, macrocell user, or other interference, and the user experience quality QoE deteriorates. In order to show that the information fusion center FC reallocates the spectrum resource to the user, the above-mentioned A type event and B type event each represent different interference situations, and the A type event is Refers to mutual interference due to communication between different home base station FAPs and users, and B type events are due to channel occupancy or strong interference due to communication between macro base stations and users of macro base stations. Refers to a situation in which a user of a station FAP is interfered with.

Beneficial Effect: The present invention is suitably used in an indoor environment, and a series of system design and experiments are carried out using the USRP RIO platform and LabVIEW, and the present technology proposal realizes lossless live video broadcasting in an indoor environment. It was effectively verified that the spectral resources can be utilized, the spectral utilization rate can be improved, and the interference coordination can be optimized. Specifically, it has the following advantages.

(1) Realized live video broadcasting with no interference and low bit error rate. The two-layer drive interference coordination technology realizes cross-layer interference coordination in both the physical layer and the application layer. If the spectral channel is selected before the live video broadcast, the non-interfering channel is selected for data communication, the QoE performance is periodically detected during the live video broadcast, and the QoE deteriorates seriously. Reallocate spectral resources. Therefore, it is possible to guarantee the effect of no interference and low bit error rate regardless of whether the transmission channel is selected before the live video broadcast or the transmission channel used during the live video broadcast.

(2) The transmission speed is high. Since the data communication is performed on the non-interference channel, the transmission speed is high, and the data obtained by the test in the actual system and the theoretically calculated data are very close to each other.

(3) System response is fast and delay is low. In the test system, if the user and home base station need to switch service channel resources, a certain amount of overhead is required to complete this process. User experience quality From the discovery of a serious degradation in QoE performance to the completion of channel replacement, the time overhead of the entire process is primarily the system's proper time overhead and the selection and distribution of spectral resource information. are categorized. According to actual system measurements, the system's proper time overhead is about 30 ms to relocate and use the new radio frequency (RF) information. This time overhead is related to the hardware actually used. The theoretical time complexity of the process, such as the selection and distribution of spectral resource information, is O (1), and the time required in the system is much less than 1 ms. Therefore, it can be seen that the time overhead of the entire response process is 30 ms, and this time is related to the performance of the hardware, and it can be said that the system response is fast. On the other hand, when the video is transmitted, the video is stuttered or the screen is distorted due to the deterioration of the user's perceived quality. Therefore, in this case, the time overhead of 30 ms for switching the service channel resource is acceptable. ..

It is a system architecture diagram of this invention. It is a realization flowchart of this invention. It is a figure of the data encapsulation in this invention. It is a figure of the resource optimization stage of this invention. It is an experimental development figure in an Example. It is a functional schematic diagram of the sensing node of this invention. It is a functional schematic diagram on the user side of this invention. It is a functional schematic diagram of the home base station of this invention. It is a functional schematic diagram of the information fusion center of this invention. It is a user side RF parameter setting diagram in an Example. It is a RF parameter setting diagram of the home base station in an Example. It is a screenshot of the video reproduction of the transmitting side in an Example. It is a screenshot of the image reproduction of the receiving side in an Example. It is a constellation diagram of the normal transmission of video data in an Example. It is a bit error rate of normal transmission in an Example. It is an energy spectrum at the time of video data transmission in an Example. It is a RF parameter diagram on the user side after adjustment in an Example. It is an RF parameter diagram of the home base station after adjustment in an Example. It is a constellation diagram after adjustment in an Example.

Hereinafter, the technical proposal of the present invention will be described in detail, but the scope of protection of the present invention is not limited to the following examples.

As shown in FIG. 1, the live video broadcasting system based on the two-layer drive interference coordination according to the present invention includes several user modules, a home base station FAP, an information fusion center FC, and a sensing node corresponding to the user. , The user module specifically refers to a smart mobile device used by the user (for example, a smart mobile mobile phone and an IPad) and has a data transmission / reception function, and the home base station FAP is limited to a limited range. It provides a network access function. The user accesses the network through the FAP, obtains a low-latency, high-speed wireless network service, adopts wireless communication between the home base station FAP and the user, and uses the home base station FAP and the information fusion center FC. During the period, wired communication is adopted, wired communication can guarantee high efficiency and no interference between the two, and the sensing node is a functional node that senses and stores nearby wireless environment information. , It also has a function to transmit data, and data is exchanged between the sensing node and the information fusion center FC by adopting a wired connection method, and the information fusion center FC is all home base stations and sensing nodes within the service range. , And, the wireless environment information collected by the sensing node is integratedly managed, and by analyzing the wireless environment data information, spectrum resources that can provide services and spectrum resources that cannot provide services can be obtained. If there is a user who needs to use the spectrum resource, the Information Fusion Center FC selects and allocates the corresponding resource from the spectrum resources that can provide the service for use by the home base station FAP and the user. To serve. Interference coordination is effectively performed by centrally managing radio resources as described above.

As shown in FIG. 2, the method for realizing live video broadcasting based on the two-layer drive interference coordination according to the present invention includes steps 1 to 4.
Step 1 is a step in which the sensing node periodically collects the spectral information of the nearby wireless environment and transmits the latest data information to the information fusion center FC. The number of sensing nodes is large and the spectral information is sensed. Due to the large span, it is necessary to encapsulate the transmitted data according to a certain data format before transmitting the information, and the format for encapsulation is, for example, as shown in FIG.
In step 2, after the information fusion center FC receives the sensing data, the fusion strategy is used to obtain a list of available spectral resources, and if there is a user who has requested access, the information fusion center FC will use the appropriate spectral resources. Is assigned for use by the user and the home base station FAP, and if there is no appropriate available resource, a message to that effect is returned to the home base station FAP and the user's request is put in the service waiting queue, and free resources are available. When it comes out, resources are preferentially allocated to users in the service waiting queue, and at the same time as resource allocation, the information fusion center FC records the spectrum usage status, and the next time the user requests access, the user's duplicate network It is a step of comparing usage records to avoid duplicate use of access or spectral resources.
Step 3 needs to occupy the user spectrum resource and at the same time feed back a set of user experience quality parameters (eg bit error rate, speed, etc.), and then monitor and analyze these user experience quality QoEs. In the step of deciding whether to reallocate the spectrum resource and if the user experience quality QoE is lower than the service demand, the Information Fusion Center FC reallocates the available spectrum resource to the user and the corresponding home base station FAP. be.
As shown in FIG. 4, first, the detection of the user experience quality QoE is monitored and analyzed, and if the user experience quality is lower than the preset threshold value, the information fusion center FC refers to the user resource correspondence table saved at the time of resource allocation. Then, it is determined whether an A type event or a B type event has occurred, and when the A type event occurs, the two communication links interfere with each other within the service range of the home base station FAP, and the two communication links interfere with each other. In order to show that the user experience quality QoE is deteriorated, the information fusion center FC reallocates the resource to the user with the shorter channel occupancy time, and when the B type event occurs, it is occupied by this user. In order to show that the channel has deteriorated the user experience quality QoE due to the interference of the macrocell base station, the macrocell user or other, the information fusion center FC reallocates the spectrum resource to the user and the above-mentioned A type. The event of type B and the event of type B each represent different interference situations, the event of type A refers to mutual interference due to communication between different home base station FAPs and the user, and the event of type B refers to mutual interference. Refers to a situation in which a user of a home base station FAP is interfered with due to channel occupancy or strong interference due to communication of a macro base station and a user of the macro base station.
Step 4 is a step in which the information fusion center FC releases the corresponding resource after the service ends.

The above implementation method mainly involves two processes, a fusion strategy and a scheduling strategy.

Ｎは、感知ノードの数であり、Ｈ_０及びＨ_１は、それぞれ空きリソース及び非空きリソースを判断する硬判定閾値であり、Ｆは、判定結果を表す。
判定結果Ｆ＝０の場合、該スペクトルリソースは、空きリソースであり、判定結果Ｆ＝１の場合、該スペクトルリソースは、非空きリソースであり、判定結果Ｆ＝２の場合、該スペクトルリソースは、正確に判断できないリソースとなり、二次判定を行い、二次判定方式について、投票メカニズムが採用され、即ち、全てのＫ_ｉ＜Ｈ_０又はＫ_ｉ＞Ｈ_１の数を統計し、投票数が半分を超えると、それを空き又は非空きリソースであると判定し、二次判定を経ても結果となるリソースが得られない場合、当意思決定ラウンドでそれを破棄し、次の新しい意思決定ラウンドの開始まで待って判定を再び行う。
融合戦略は、システム内で一定の時間周期が実行される。該時間周期は、システム感知機能の優劣と密接に関連している。融合戦略の実行周期が、調整可能なパラメータとして設定され、後続のデバッグ及び使用中に、リアルタイムに変更可能である。融合戦略の理論的な時間オーバーヘッドは、Ｏ（ｎ）であり、そのため、サイクル周期の設定は、融合過程が完了できることを保証すればよい。 A, Fusion strategy When the information fusion center receives the data sent from each sensing node, it first performs sampling processing on all the data and sets the sampling rate to M (the magnitude of M is determined by the system performance). After the sampling process is completed, the average Ki is taken for the capability detection data of the same frequency band of different sensing nodes, _i represents the different sensing nodes, and it is determined whether or not the spectrum is open by the following rigid determination formula.

N is the number of sensing nodes, H ₀ and H ₁ are hard judgment thresholds for judging free resources and non-free resources, respectively, and F represents the judgment result.
When the determination result F = 0, the spectrum resource is a free resource, when the determination result F = 1, the spectrum resource is a non-free resource, and when the determination result F = 2, the spectrum resource is. It becomes a resource that cannot be judged accurately, and a secondary judgment is made, and a voting mechanism is adopted for the secondary judgment method, that is, the number of all _{Ki <H 0 or Ki} > H ₁ is statistic, and the number of votes is halved. If it exceeds, it is judged as a free or non-free resource, and if the resulting resource is not obtained even after the secondary judgment, it is discarded in this decision-making round and the next new decision-making round. Wait until the start and make the decision again.
The fusion strategy runs a fixed time cycle within the system. The time cycle is closely related to the superiority or inferiority of the system sensing function. The execution cycle of the fusion strategy is set as an adjustable parameter and can be changed in real time during subsequent debugging and use. The theoretical time overhead of the fusion strategy is O (n), so setting the cycle period may ensure that the fusion process is complete.

B. Scheduling strategy The scheduling strategy is divided into two parts: the resource allocation stage and the resource optimization stage. During the resource allocation phase, the system promptly allocates available resources to new users of the network, allowing this user to obtain available resources in the shortest possible time. In the resource optimization stage, the system analyzes based on a set of user experience quality parameters fed back from the user after using the obtained resources, and if the user experience quality is not good, the system uses the allocated resources. Adjust to improve user experience quality.

The complete procedure for the scheduling strategy is as follows:

(A) When a user accesses the network and requests the system to allocate resources for the first time, the resource allocation stage is entered. At this stage, the system randomly selects one available spectral resource from the candidate available spectral resources and assigns it to the user, ensuring that the user can obtain the available resource in the shortest possible time. And start data transmission. At the same time, the information fusion center stores the allocated resource information and the corresponding user information in the user resource correspondence table to facilitate the management of spectral resources.

(B) When the user obtains the available spectrum resource, the resource allocation stage is completed and the resource optimization stage is entered. The continuation range of the optimization stage is the entire process in which the user uses the resource, and when the user leaves the network, the optimization stage ends and the user leaves the service. In the entire resource optimization stage, the service is detected according to a fixed time cycle (adjusted according to the actual environment and demand) based on the user experience quality QoE. If the user experience quality QoE index is lower than the preset threshold (set according to the demand for the service), the system adjusts the user and the spectral resources used by the user, and other available spectral resources for the user. Assign to.

Example:
1. Experimental platform

In software defined radio, all remaining functions are performed by software-defined design, except that basic frequency conversion, A / D conversion, D / A conversion and RF drive are realized by the hardware platform USRP RIO 2943R. .. In the entire communication process, almost all extended functions, except for basic transmission / reception functions, require self-design and programming.

For a series of physical parameters of the NI USRP RIO 2943R, the adjustable frequency range is 1.2GHz to 6GHz, the real-time bandwidth is 40MHz, the PCIex4 bus speed is 800MB / s, and the chip is a Kintex7 FPGA.

As the software part of the experiment, Labview 2015 will be used for designing and debugging the program. In addition to the RF transmission / reception drive provided by the software itself, the entire invention is realized by extending a series of functions required by the present invention.

2. Setting the experimental environment As shown in Fig. 5, the experimental arrangement will be specifically developed in the test system. In the experimental environment, two users, the corresponding home base station, one information fusion center, and several sensing nodes are installed. During the experiment, the two users can be sources of interference with each other, so there is no need to install extra human interference terms.

The communication method between the user and the home base station is wireless communication, and the communication method between the home base station and the information fusion center is wired communication, using an optical fiber connection, and the sensing node and the information fusion center. Is also connected by an optical fiber. According to such a setting method, it is possible to effectively test the actual effect at the time of use by the user while ensuring the reliability of all communication on the system side.

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

In order to reduce the difficulty of deploying the sensing node, the setting of the program of the sensing node part is relatively easy, because it senses the surrounding wireless environment data, packages the data and puts it in the information fusion center. This is because it should be sent. Since the USRP platform can only detect data within a narrow bandwidth at the same time, it is necessary to add a frequency sweep function to it to sequentially scan the data on the spectrum of each section within the configured bandwidth range. be. A schematic diagram of a specific sensing node function program is shown in FIG. When the program is started after inputting the parameters of the set RF transmission / reception data, the data starts to be sensed, and then the sensed data is encapsulated according to the data format shown in FIG. 3 and then sent to the information fusion center by the UDP method. .. Under the control of the frequency sweep function module, the above sensing flow is performed in different frequency bands without gaps. After completing a task in the preset sensing range, the next sensing task will resume. Since the range of 1.2 GHz to 6 GHz is too large to be easy to debug and observe the results during the experiment, in this example, some frequency bands within the range of 2.2 GHz to 2.8 GHz are used during the test. The reliability of the experimental results is guaranteed while accelerating the experimental speed by selecting and testing.

User and home base station experiment settings:
Users and home base stations are primarily responsible for data communication, video transmission and transmission result display, and data statistics during the experiment, so two single-antenna users can be placed on a single USRP RIO device. Utilizing the characteristic of being, the user and the home base station are placed in the same USRP RIO device. Although both are physically located on the same device, data communication between them is carried out by wireless channels, thus effectively testing the ability to wirelessly transmit video. Taking the case where the user transmits data to the home base station as an example, FIG. 7 is a schematic function diagram on the user side, and FIG. 8 is a schematic function diagram of the home base station.

As can be seen from FIG. 7, on the user side, it starts from the source, undergoes operations such as QAM modulation, guard interval insertion, and framing, and then is transmitted to the radio channel by the RF transmission module. The RF transmission module is provided with an external extended interface for calling from the transmission parameter change module, and can change transmission RF parameters such as transmission center frequency, local oscillation and gain in real time, for example. Since video data is used during system testing, the source is a data packet processed by VLC software.

As can be seen from FIG. 8, functionally, the home base station is functionally divided into two parts: data exchange with the user and data exchange with the information fusion center. For the data part exchanged with the user, data reception is taken as an example. It receives radio information from the antenna, passes through the RF receiver module, performs frame synchronization, frame analysis, channel balancing, and QAM demodulation, and finally reaches the sink. The sink is VLC software, and after obtaining the data, VLC can observe the playback quality while playing back the video through internal decoding.

Information Fusion Center Experimental Settings:
For the Information Fusion Center, the functions that need to be performed include fusion strategies, monitoring and coordination of user experience quality, and management and allocation of spectral resources. In the experimental test, an independent information fusion center was set up and the test was conducted.

FIG. 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, the data sent from the home base station and the data sent from the sensing node. Therefore, if the source of the received data is different, the module of data processing is also different. When data is received from the home base station, the data enters the user experience quality monitoring module, is determined to meet the quality of service requirements, and if not, selects a new available spectrum resource from the storage module. It informs the home base station to change the spectral resource via the UDP transmission module. When the data is received from the sensing node, the data enters the fusion strategy module, is processed, and then the available spectral resources are obtained, stored in the storage module and used. For different data sources, different UDP port numbers are used during UDP communication, so different data sources can be easily identified.

3. Experimental flow Step 1) Set preset parameters. A set of preset parameters must be set before launching any program. The initial RF parameters of the user, the home base station, and the RF parameter settings of the sensing node are shown in Explanatory FIGS. 10 and 11. FIG. 10 shows the setting status of the RF parameter on the user side, in which the initial center frequency is 2.4 GHz, the local oscillation frequency is -1 Hz, and the transmission gain is 0 dBm. FIG. 11 shows the settings of the RF parameters on the corresponding home base station side, the center frequency of the reception frequency is 2.4 GHz, the local oscillation frequency is -1 Hz, and the reception gain is 0 dBm.

Step 2) Execute the program and start data communication. Next, the VLC script file is opened to start the generation of the video source data and the reproduction of the received video source data. Images of transmitted and received images are shown in FIGS. 12 and 13. FIG. 14 is a constellation diagram on the receiving side, and it can be seen that the BPSK modulation method is used and the constellation diagram is clear. FIG. 15 is a diagram of the average bit error rate and time, and the bit error rate is almost zero during stable transmission. FIG. 16 is a frequency energy spectrum at the time of video data transmission, and it can be clearly seen that the center frequency is the midpoint and both sides occupy half of the bandwidth, resulting in a total transmission bandwidth of 3 MHz.

Step 3) Manually change the frequency band used by one user so that the two users transmit data in the same frequency band, causing an interference phenomenon. Test whether the scheduling strategy in your system is performing its intended function.

Step 4) The system reallocates new resources to the user who has the interference, and the video transmission returns to normal. 17 and 18 show the case where one user and the home base station adjust the frequency to be used under the control of the scheduling strategy after artificially adding interference, and after the adjustment, the occupied center frequency thereof. Is 2.7 GHz. FIG. 19 is a constellation diagram of a user occupying a frequency of 2.7 GHz and a home base station.

During the experiment, by theoretical analysis and calculation, there are the following calculations. The data length of one frame is (1 + 1 + 706) × (16 + 64) = 56640 Samples, including the LTF sequence, the SIG sequence and the data, the interval length is 16 and the data length is 64. The actual data is 706 × 64 = 45184 bits, the speed is 45184 bits ÷ 16 ms / 1s = 2.824 M / s, and the transmission speed is 56640 ÷ 16 ms / 1 s = 3.54 M / s. Since data communication is performed on a non-interference channel, the transmission speed of the present invention is high. As can be further understood from the above embodiment, the present invention selects spectral channels, selects non-interfering channels for data communication, and cycles QoE performance during live video broadcasting. If the QoE drops seriously, the spectral resources are reassigned. Therefore, regardless of whether the transmission channel is selected before the live video broadcast or the transmission channel used during the live video broadcast, the effect of no interference and low bit error rate can be guaranteed, and the transmission can be performed. The speed is high.

Claims (5)

It is a method of realizing live video broadcasting based on two-layer drive interference coordination.
It is a step in which the sensing node periodically collects the spectral information of the nearby wireless environment and transmits the latest data information to the information fusion center FC, and before transmitting the information, the transmitted data is transmitted according to the corresponding data format. Step 1 of encapsulation and
After the Information Fusion Center FC receives the sensing data, the Fusion Strategy is used to obtain a list of available spectral resources, and if there is a user requesting access, the Information Fusion Center FC allocates the corresponding spectral resource to the user. And for use by the home base station FAP, if there are no suitable available resources, a message to that effect is returned to the home base station FAP and the user's request is put in the service waiting queue, and when free resources are available, the service is available. Resources are preferentially allocated to users in the wait queue, and at the same time as the resources are allocated, the information fusion center FC records the spectrum usage status, and the next time the user requests access, the user's duplicate network access or spectrum resource Step 2 to compare usage records to avoid duplicate use of
It is necessary for the user to occupy the spectral resource and at the same time feed back the corresponding user experience quality parameter, and then by monitoring and analyzing the user experience quality QoE, it is decided whether to reallocate the spectrum resource, and if the user experience quality If the QoE is lower than the service demand, the Information Fusion Center FC reallocates the available spectral resources to the user and the corresponding home base station FAP, and step 3.
A method for realizing live video broadcasting based on two-layer drive interference coordination, which includes step 4 in which the information fusion center FC releases the corresponding spectral resource after the end of the service. As a specific process of the fusion strategy in step 2, when the information fusion center FC receives the data sent from each sensing node, it first performs sampling processing on all the data, sets the sampling rate to M, and samples. After the processing is completed, the average Ki is taken for the capability detection data of the same frequency band of different sensing nodes, _i represents the different sensing nodes, and it is determined whether the spectrum is open by the following rigid determination formula.

N is the number of sensing nodes, H ₀ and H ₁ are hard judgment thresholds for judging free resources and non-free resources, respectively, and F represents the judgment result.
When the determination result F = 0, the spectrum resource is a free resource, when the determination result F = 1, the spectrum resource is a non-free resource, and when the determination result F = 2, the spectrum resource is. It becomes a resource that cannot be judged accurately, so a secondary judgment is made and
The secondary decision is made by the voting mechanism, i.e., statistics the number of all _{Ki <H 0 or Ki} > H ₁ , and if the number of votes of the sensing node exceeds half, it is free or non-free resource. If it is determined that there is, and the resulting resource is not obtained after the secondary decision, it is discarded in this decision-making round, and the decision is made again after waiting until the start of the next new decision-making round. The method for realizing live video broadcasting based on the two-layer drive interference coordination according to claim 1 . The fusion strategy in step 2 above is executed in the system at the corresponding cycle, the execution cycle of the fusion strategy is set as an adjustable parameter and is changed in real time during subsequent debugging and use, the theory of fusion strategy. The method for realizing live video broadcasting based on the two-layer drive interference coordination according to claim 1 , wherein the time overhead is O (n). The process of reallocating spectral resources in step 3 above is a resource optimization stage, and as a specific operation method,
First, the detection of the user experience quality QoE is monitored and analyzed, and if the user experience quality is lower than the preset threshold value, the information fusion center FC refers to the user resource correspondence table saved at the time of resource allocation, and causes an A type event. Or, it is determined whether a B type event has occurred, and if an A type event occurs, the two communication links interfere with each other within the service range of the home base station FAP, and the user experience quality QoE deteriorates. When the Information Fusion Center FC reallocates the resource to the user with the shorter channel occupancy time and a B type event occurs, the channel occupied by this user is the macrocell base station. The Information Fusion Center FC reallocates spectrum resources to the user to indicate that the user experience quality QoE has deteriorated due to the interference of the macrocell user or others.
The above-mentioned A type event and B type event represent different interference situations, respectively, and the A type event refers to mutual interference due to communication between different home base station FAPs and the user, and B type. The event according to claim 1 , wherein the event refers to a situation in which the user of the home base station FAP is interfered with due to channel occupancy or strong interference due to the communication of the macro base station and the user of the macro base station. A method for realizing live video broadcasting based on two-layer drive interference coordination. A video live broadcasting system based on two-layer drive interference coordination using the method for realizing video live broadcasting based on the two-layer drive interference coordination according to any one of claims 1-4, wherein some user modules and home bases are used. Includes station FAP, information fusion center FC, and sensing nodes corresponding to the user.
Specifically, the above user module refers to a smart mobile device used by a user, and has a data transmission / reception function.
The home base station FAP provides network access, the user accesses the network through the home base station FAP, and wireless communication is adopted between the home base station FAP and the user, and the home base station FAP is used. Wired communication is adopted between the information fusion center FC and the information fusion center FC.
The sensing node is a functional node that senses nearby wireless environment information, stores the sensed information, and at the same time sends data to the information fusion center FC, and between the sensing node and the information fusion center FC, Uses a wired connection method to exchange data and
The information fusion center FC integrates and manages all home base stations, sensing nodes, and wireless environment information collected by the sensing nodes within the service range, and provides services by analyzing the wireless environment data information. If there is a user who needs to use the spectrum resource after obtaining the spectrum resource that can provide the service and the spectrum resource that cannot provide the service, the Information Fusion Center FC will select the spectrum resource that can provide the service. A live video broadcasting system based on two-layer drive interference coordination, characterized in that the relevant resources are selected and allocated for use by the home base station FAP and users.

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