Patent Description:
As the research and promotion of railway mobile communication technology are continuously directed towards broadband and intellectualization, it has been determined that China's railways will adopt <NUM>-R to realize the next generation of railway mobile communication system.

International Organization for Standardization 3GPP Standard (The Third Generation Partnership Project) has successively introduced a series of standards based on mission critical communication mechanism: MCPTT (Mission Critical Push to Talk), MCData (Mission Critical Data) and MCVideo (Mission Critical Video), which are collectively called MCX (Mission Critical Service ), and they will become the main direction for cluster communication's further development. MCX technology meets the basic functional requirements of railway cluster communication and dispatch communication services, and has become a solution for domestic and foreign railway clustering and dispatching communications. Especially, the proposal of MCVideo communication technology will greatly improve the visualization and intellectualization level of railway communication.

The Chinese invention patent application "A speaking right control method based on MCVideo cluster system", with publication number <CIT>, realized the speaking right control based on MCVideo Cluster System, but did not introduce how to control video transmission in detail. The Chinese invention patent "Method for managing MCVIDEO communication in off-network MCVIDEO Communication System", with the number of announcement of grant of patent right <CIT>, introduced the direct video communication method between different MCVideo terminal devices without the support of MCVideo server under off-network condition, but did not introduce the video transmission control method during group call. Beijing Jiaotong University's <NUM> paper "Research and Implementation of MCVideo Video Transmission Function in Broadband Clustering Switching System" introduced the method of video transmission right control in MCVideo broadband cluster switch system, but did not control the category permissions of different MCVideo terminal users. In addition, in general, the above schemes are all based on 3GPP standards.

However, the group call and video transmission control under MCVideo system introduced by 3GPP are mainly for public safety network, while the exclusive and particular railway mobile communication network is to some degree different from public safety network. In addition, the application scenarios of railway Clustering communication and dispatch communication services are too special for the MCVideo mechanism in 3GPP standard to apply.

<CIT> describes a wireless device that transmits, to a second wireless device via an internet protocol multimedia subsystem (IMS) network entity, a session initiation protocol (SIP) invitation. The SIP invitation may comprise a session description protocol (SDP). The SDP may comprise a media type and one or more attributes. The media type may identify a protocol for controlling operational orders. The controlling operational orders may comprise at least: mechanical operational orders; and electrical operational orders. The one or more attributes may identify a format of the protocol to establish a SIP session. The wireless device may receive, from the second wireless device via the IMS network entity, a SIP confirmation for the SIP session. The wireless device may control the second wireless device employing the controlling operational orders identified by the media type.

<CIT> relates to a communication method and system for converging a 5th-Generation (<NUM>) communication system for supporting higher data rates beyond a 4th-Generation (<NUM>) system with a technology for Internet of Things (IoT). The disclosure may be applied to intelligent services based on the <NUM> communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. In the disclosure, a system and a method to handle media transmission in the Mission Critical (MC) systems or MC Video system are provided. According to the system and the method, wastage of network resources can be avoided and other participants in the group can be given chance to transmit important data as maximum number of transmissions at a time in a group call are limited by network capacity. Accordingly, efficiency of the MC Video system can be improved.

The purpose of the present Invention is to provide a method for group call video transmission control of the railway MCVideo system, which can meet the permissions control requirements of various user terminals in the application scene of railway Clustering communication and dispatching communication services, is beneficial to more reasonable application of railway private network resources, and can ensure the feasibility, controllability and high efficiency of video transmission in railway video group calling.

The invention relates to a method, as further defined in claim <NUM>, for group call video transmission control of a railway Mission Critical Video, MCVideo, system.

According to the technical proposal provided by the Invention above, it can be seen that different kinds of video transmission permission can be respectively configured for different types of user terminals according to the characteristics and application strategies of the user terminals, based on this, a more perfect method of video transmission control, transmission notice and receipt control (collectively referred to as video transmission control method) is proposed; through the user video transmission permission configuration and video transmission control method, the application requirements of railway clustering and dispatching communications are greatly satisfied, and the efficiency of command and communication are improved.

In order to explain the technical scheme of the embodiments of the present Invention more clearly, the appended drawings to be used in the description of the embodiments will be briefly described below. It is obvious that the drawings described below are only some embodiments of the present Invention, and other drawings can be obtained from these drawings without any creative effort by those of ordinary skill in the art.

A clear and complete description of the technical scheme of the embodiments of the Invention will be given below in conjunction with the appended drawings in which the embodiments of the present Invention are described, and it will be apparent that the described embodiments are only part of, and not all of, the embodiments of the Invention. Based on the embodiments of the present Invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present Invention.

First, the terms that may be used in this article are explained as follows:
The terms "involving", "including", "containing", "having" or other descriptions with similar meanings shall be construed as non-exclusive inclusion. For example, involving a technical characteristic element (such as raw material, constituent, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction condition, processing condition, parameter, algorithm, signal, data, product, etc.) should be interpreted as including not only a technical characteristic element explicitly listed, but also other technical characteristic elements well known in the art that are not explicitly listed.

Railway MCVideo system group call video transmission control method provided by the present Invention is described in detail below. Content not described in detail in the embodiments of the present Invention is the prior art well known to those skilled in the art. Where specific conditions are not specified in the embodiments of the present Invention, implementations shall be performed according to the conventional conditions in the art or the conditions recommended by the manufacturer. For instruments used in the embodiment of the present Invention, if manufacturer is not indicated, are conventional products available in market.

As shown in <FIG>, A method for group call video transmission control of the railway MCVideo system mainly comprises the following steps:
Step <NUM>. When a user terminal's registration request is received, the MCVideo server configures a corresponding permission for the user terminal according to the category of the user terminal.

In the embodiment of the present Invention, the preferred embodiment of configuring the corresponding permission for the user terminal according to the category of the user terminal is described as follows:.

In the embodiment of the present Invention, all the members in the video group call are user terminals, and different role names are given to the user terminals according to the actions of video sending and video receiving of the user terminals. For example, the user terminal sending video in the video group call is called the video sender, and the user terminal receiving video is called the video receiver. The roles of the video sender and the video receiver can be interchanged, for example, the user terminal A sent video at the last moment, then it acts as the video sender; at the next moment the user terminal A receives the video, it acts as the video receiver.

Step <NUM>. when the MCVideo server receives the sending video request from the video sender, it verifies the video sender and the sending video request, returns the response message carrying the SSRC number assigned to the video sender to the video sender after passing the verification, and receives the video stream sent by the video sender; at the same time, the relevant information of the video sender is sent to other user terminals in the video group call where the video sender is located; The SSRC number aforesaid represents the synchronization source number.

In the embodiment of the present Invention, when the video group call is just established, the initiator of the group call actively sends its own video, and other members in the group actively receive the video of the initiator, at this time, the process is automatically completed and does not need to be intervened by the user terminal. The process of video group call establishment is as follows: (<NUM>) A user terminal wants to initiate a video group call, and sends a video group call initiating request to the MCVideo server by dialing the group call number, and this user terminal is the initiator of the group call; (<NUM>) After receiving the video group call request, the MCVideo server connects the call, and adds other members in the group into the group call one by one, and then the video group call is established.

In the process of video group call, when the video sender requests to send local videos, the MCVideo server needs to verify the video sender and the sending video request to decide whether to allow the relevant request. The verified content may include whether the video sender is in the video group call, whether the format of the sending video request is correct, and whether the video sender has a video being sent. If the video sender is in the video group call, with correct format of sending video request, and has no video being sent, then it passes the verification, otherwise, it fails; after passing the verification, the video sender is allowed to send the video, and has a corresponding SSRC number assigned; if the verification fails, the video sender is refused to send the video; the MCVideo server correspondingly returns a message to the video sender according to the verification result, and then instructs the video sender to or not to send the video stream. In addition, while the MCVideo server above is receiving the video stream sent by the video sender, if it receives the request of terminating video sending from the video sender, it verifies the video sender and the request of terminating the video sending. Similar to the previous, the verified content can include whether the video sender is in the video group call, whether the format of the video request is correct, and whether the video sender has a video being sent. If the video sender is in the video group call, with correct format of the video request to terminate sending, and there is a video being sent, then it passes the verification, otherwise, it fails. After passing the verification, the response message allowing to terminate sending is returned to the video sender.

In addition, after receiving the video stream sent by the video sender, the MCVideo server aforesaid also sends the relevant video transmission notice to each user terminal, so as to inform other user terminals in the video group call of the current state change of the video sender. Specifically, the MCVideo aforesaid server sends the relevant information of the video sender (for example, the user terminal's user name, SSRC number, functional number, etc.) to other user terminals in the video group call where the video sender is located, and the other user terminals display it in a list, so that the video stream to be received can be selected according to needs; afterwards, when a new user terminal joins in the video group call, the relevant information of the video sender is sent to the new user terminal. When the MCVideo server aforesaid receives the request of terminating sending video sent by the video sender and allows the video sender to terminate video sending, or after the video sender exits the video group call, the MCVideo server aforesaid sends a video sending terminating notice to other user terminals in the video group call.

Step <NUM>. when the MCVideo server receives the video receiver's request of receiving a designated video sender's video, the MCVideo server carries out verification in combination with the video receiver's permission, returns the response message of allowing the receipt to the user terminal after passing the verification, and sends the video stream of the designated video sender to the video receiver.

As described earlier, the members of the video group call are informed of video stream information of each member in the video group call through video transmission notice, so that the video stream by a designated video sender can be received as needed. Similarly, after receiving the relevant request from the video receiver, the MCVideo server needs to verify in combination with the video receiver's permission. In addition to verifying in combination with the permission items configured in Step <NUM> (for example, verifying whether the number of video channels received by the video receiver reaches the upper limit and whether there is the permission to view the video of the designated video sender), the MCVideo server also needs to verify the identity of the video receiver and the content of request (for example, verifying whether the video receiver is a member of the video group call, whether the format of the request of receiving the designated video sender's video is correct, etc.), if the requirements of permission of configuration in Step <NUM> are satisfied, it is the video group call member, with correct format of the request of receiving the designated video sender's video, the verification is passed; otherwise, the verification fails; according to the verification result, a response message of allowing the receipt or not refusing the receipt is fed back to the video receiver. If the receipt is allowed, the video stream of the designated video sender is sent to the video receiver. While the MCVideo server is sending the video stream of the designated video sender to the video receiver, if the request of video receiving termination from the video receiver is received, the video receiver and the video receiving termination request are verified, for example, whether the video receiver is a member of the video group call, whether the format of the request of video receiving terminating is correct, and whether the video receiver currently has the video being received; if the video receiver is a member of the video group call, with correct format of the request of video receiving terminating, and there is currently a video being received, the verification is passed, otherwise, the verification fails; after the verification is passed, the response message allowing to terminate receiving is returned to the video receiver.

In order to facilitate understanding, the following four parts are further introduced: user terminal video transmission permission configuration, video sending control, video transmission notice, and video receiving control.

According to user characteristics and application strategies, MCVideo Server assigns different kinds of video transmission permission to different categories of user terminals when establishing a video group call. As shown in <FIG>, it mainly includes:.

Each user terminal and the MCVideo server send control messages through video to realize the process that each user terminal uploads local video to the MCVideo server. Of course, in this stage, the user terminal sending video is the video sender. Considering that the names of video sender and video receiver are mainly used to distinguish the roles of different user terminals, but this stage only involves the role of video sender, therefore, in the introduction of this part, the name user terminal is still used. As shown in <FIG>, it mainly includes:.

The MCVideo server informs other users of the current state change of the video sender by sending relevant video transmission notice to each user terminal.

As shown in <FIG>, it is a flowchart of processing video sending notice. As shown in <FIG>, it is a flowchart of processing video sending terminating notice.

Each user terminal and MCVideo server use video receiving control to realize the process of each user receiving other user's video from the MCVideo server. As shown in <FIG>, it mainly includes:.

On the basis of the above video transmission control method, the present Invention also provides a functional number transmission method of the video transmission control process, a processing strategy for user terminal receiving multi-channel video, and a multi-MCVideo system video transmission control method.

Functional Number (FN) is a number defined according to the function of the position, or role of the user terminal, it is an important user identification in railway dispatch communication services. The standard 3GPP MCVideo video transmission control has not covered functional number information. According to the specific application requirements of railway dispatch communication, the functional number information is added to the video transmission control information, to help each user accurately grasp the source of specific role of the video stream, and it will improve the command communication efficiency greatly. Therefore, the video transmission control method above carries the functional number of the user terminal corresponding to the due video sender, specifically, the <NUM>) and <NUM>) parts of the video transmission control aforesaid and the <NUM>) to <NUM>) parts of the video transmission notice.

<FIG> shows the encoding format of the functional number field, which mainly includes: the functional number field ID (FN field ID), the functional number length (FN length) and the functional number (FN).

Generally speaking, if the length of the FN of the functional number is not (<NUM>+multiples of <NUM>) bytes, the Padding is (<NUM>+multiples of <NUM>) bytes, the value of the Padding byte is <NUM>, and the Padding byte is ignored by the receiver.

In the embodiment of the present Invention, the number of functional numbers of the user terminal is one or more, and when the number is more than one, only the functional number with the highest priority is carried; the priority order is: train number functional number > locomotive functional number > carriage number functional number > other functional number; wherein, the other functional numbers represent functional numbers of other categories except train number functional number, locomotive functional number and carriage number functional number.

In the video group call, the user terminal (the video receiver) can receive multiple channels of videos from other user terminals (the video senders), and the video users received by each user terminal are not uniform. In the video group call process, the video selected by each user terminal may change, that is, the video selected by each user terminal is determined by the user terminal itself. Therefore, if the MCVideo server realizes the processing work of synthesizing multi-channel videos requested by each user terminal into one channel video, the video processing load of the MCVideo server is easy to be high due to the different video synthesis strategies of different user terminals, and the real-time performance of video transmission is likely to be greatly affected.

In the embodiment of the present Invention, it is proposed that each user terminal realizes the multi-channel video display work, namely, the MCVideo server maintains the video transmission control decision and forwards the corresponding video stream to each user terminal according to the strategy, and each user terminal completes the processing of multi-channel video received by itself. Wherein, the key point is that the MCVideo server uniformly controls and distributes the SSRC number of the video stream of each user terminal, and each user terminal requests and distinguishes other users' video streams through SSRC.

As shown in <FIG>, the principle of the strategy to process multi-channel video received by a user terminal is shown. Different SSRC numbers are assigned to different video senders by MCVideo server, and video receivers distinguish different video senders according to SSRC numbers. After receiving video streams from different video senders, the sources of different video streams are distinguished according to SSRC numbers.

In the embodiment of the present Invention, when the user terminal in the video group call belongs to multiple MCVideo systems, the MCVideo system to which the video group call belongs is taken as a main control system, and other MCVideo systems are taken as participating systems; the MCVideo server in the main control system is responsible for receiving the request from the video sender and the video sender, and for feeding back the corresponding response message after the permission verification; the video sender and the video sender in the main control system asforesaid communicate directly with the MCVideo server in the main control system, and the video sender and the video sender in the participating system communicate with the MCVideo server in the main control system through the MCVideo server in the MCVideo system it belongs to. <FIG> shows the principle of video transmission control method in multi-MCVideo systems.

In the embodiment of the present Invention, the MCVideo system to which the video group call belongs refers to the MCVideo system used for managing the video group call. In the process of establishing the video group call, the MCVideo server of such MCVideo system is also responsible for adding each member (the user terminal) into the video group call, and stores all information configurations of the video group call, including group information and information of each member.

Through the above description of the embodiments, those skilled in the art can clearly understand that the above embodiments can be implemented by software or by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical scheme of the above embodiments may be embodied in the form of a software product that may be stored in a non-volatile memory (which may be a CD-ROM, a U disk, a removable hard disk, etc.), including multiple instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in the various embodiments of the present Invention.

Claim 1:
A method for group call video transmission control of a railway Mission Critical Video, MCVideo, system, comprising the following steps:
when a registration request of a user terminal is received by a MCVideo server, configuring a corresponding permission for the user terminal according to a category of the user terminal; wherein a user terminal sending video in a video group call is called a video sender, and a user terminal receiving video is called a video receiver;
when a sending video request is received by the MCVideo server from a video sender, verifying by the MCVideo server the video sender and the sending video request in combination with the corresponding permission of the video sender, returning by the MCVideo server a response message carrying a Synchronization Source, SSRC, number distributed to the video sender's video stream to the video sender after passing the verification, and receiving by the MCVideo server the video stream sent by the video sender; at the same time, sending by the MCVideo server relevant information of the video sender to other user terminals in the video group call where the video sender is located;
when a request to receive the designated video sender's video is received by the MCVideo server from a video receiver, verifying the video receiver and the receiving video request in combination with the corresponding permission of the video receiver; after passing the verification, returning a response message of allowing the receipt to the user terminal, and sending the video stream of the designated video sender to the video receiver.