KR20080094417A - Wireless network information transmission method and apparatus in real-time multimedia services - Google Patents

Abstract

A network context information transmission method in a real-time multimedia service using a wireless communication network and a device therefor are provided to reduce unnecessary information as possible by shortening transmission intervals without violating standards used in a real-time multimedia transmission service, thereby decreasing loads for a limited wireless network. Session connection for data transmission and channel environmental information is performed between a server and at least one client, and session information is requested by a random client(602). Overall session information belonging to each channel of a network is confirmed(604,606). Session information of the corresponding channels is included in an RTP(Real-time Transport Protocol) packet, from the overall session information, and the RTP packet is transmitted to the client who demands the session information(608).

Description

Method and apparatus for transmitting network status information in real time multimedia service using wireless communication network {WIRELESS NETWORK INFORMATION TRANSMISSION METHOD AND APPARATUS IN REAL-TIME MULTIMEDIA SERVICES}

1 is a schematic diagram illustrating an example of a real-time interactive multimedia service using a conventional wireless communication network

2A, 2B, and 2C are diagrams illustrating the configuration of an RTCP (Render Control Protocol) RSR (SRender Report), an RTCP APP (Application), and an RTCP SDES (Source Description) packet in a real-time bidirectional multimedia service using a conventional wireless communication network.

3 is a block diagram of a compound RTCP packet in a real-time two-way multimedia service using a conventional wireless communication network

4 is a configuration diagram of a Real-time Transport Protocol (RTP) packet header and an extension header used for data transmission according to an embodiment of the present invention.

5 is a block diagram of an RTP packet header including an extension header in a real-time bidirectional multimedia service using a wireless communication network according to an embodiment of the present invention;

6 is a schematic flowchart of a transmission cycle of an RTP including an extension header in a real-time bidirectional multimedia service using a wireless communication network according to an embodiment of the present invention;

The present invention relates to a real-time multimedia service using a wireless communication network, and in particular, the total session information (number of participants transmitting data and data) between each server through a real-time transport protocol (RTP) packet or a RTP control protocol (RTP) packet transmission. The present invention relates to an information transmission method for reducing the load on a limited wireless network by checking the number of participants) or an RTCP transmission cycle, and transmitting information on its own radio section to an opposite terminal.

The multimedia services through the wireless Internet include information providing services, interactive services, entertainment services, mobile e-commerce services, and location-based services. Among them, interactive services may be classified into voice interactive services and video interactive services. The voice interactive service is a service for expanding the area of a voice call such as a chat / meeting service, and the video interactive service includes a video phone service between mobile communication terminals or between a mobile communication terminal and a wired terminal. The Video On Demand (VOD) service, which stores video media and downloads or displays them in real time regardless of time, is also a service derived from interactive services.

VOD service includes various video clip download service, real time relay service, and connection service with messaging service. VOD transmission method has download method and streaming method, and MPEG to transmit massive multimedia information through limited transmission bandwidth resources Compressor method such as -4 is used.

In order to transmit multimedia content in a wireless section, a separate upper layer is required for a general wireless data protocol, and it is common to use a Real-time Transport Protocol (RTP) to guarantee some real time. RTP can be defined as a protocol that provides real-time data transmission, such as voice and image data, over multicast or unicast. RTP also does not perform resource reservations and therefore does not guarantee quality of service such as timely or sequential delivery.

Meanwhile, RTCP (RTP Control Protocol) is a protocol for controlling RTP, which is mainly used in a multicast environment, and periodically transmits control packets to all receivers in a session and performs quality of service (QoS) monitoring from feedback data. do. This function is performed by RTCP's Send Report (SR) and RTCP's Receiver Report (RR).

To this end, information such as the number of lost packets, jitter intervals, and delay time with previous packets is used. That is, when the multimedia content is provided through the wireless Internet, RTCP is involved in monitoring data transmission and transmitting session related information.

In order to use a high-speed real-time multimedia service in a mobile or stationary state using a wireless terminal, research is being conducted to effectively transmit a large amount of video information. In particular, in the wireless channel situation where the multi-path fading and the time-put change of the signal (though-put) are severe, the quality of the reception screen is deteriorated due to the deterioration of the picture quality of the transmission screen, the loss of frames, and the delay. Occurs. Therefore, in order to transmit high quality video between terminals in real time interactive multimedia services such as video call service, it is necessary to develop a technology that analyzes a wireless channel environment and transmits high quality video optimized for a network situation.

1 is a schematic diagram illustrating an example of a real-time interactive multimedia service using a conventional wireless communication network. 1, in the conventional case, multimedia data is transmitted at a constant rate regardless of network conditions. In the case of a wireless network, a fading phenomenon, a change in through-put, and a limited number of users due to a limited bandwidth compared to a wired network may reduce the quality of real-time service due to time delay due to congestion.

The real-time transport protocol (RTP) is mainly used for real-time packet data transmission in such a wireless network. Since RTC does not guarantee quality of service such as timely delivery or sequential delivery, information about the network such as packet loss rate and time delay can be transmitted through RTCP (RTP Control Protocol). By utilizing the information, it is possible to provide the multimedia service optimized for the network.

2A, 2B, and 2C show configuration diagrams of an RTCP control report (SRTCP) report, an RTCP APP (application), and an RTCP SDES (source description) packet in a real-time bidirectional multimedia service using a conventional wireless communication network. .

First, FIG. 2A shows that the RTC receiver sends SR and RR, respectively, if it is a simultaneous sender or not, to provide feedback on reception quality. If a site has sent any data packet during the RTCP transmission interval since the last report, it sends an SR; otherwise it sends an RR. 2A illustrates an SR packet.

2B is used to describe the source name including the CNAME (Canonical NAME). CNAME provides a binding with an identifier for the source that remains on the fly to prevent SSRC identifier changes that occur when a randomly allocated SSRC identifier crashes or when the program is restarted.

Figure 2c is a packet to be used for experimental purposes without having to register the value of the packet type when a new application or a new function is developed. APP packets with unrecognized names are ignored.

All RTCP packets should be transmitted in the form of a compound packet consisting of at least two individual packets, the overall configuration of the RTCP SR, RTCP APP, RTCP SDES outlined above is as shown in each figure.

In the case of a real-time multimedia service using a conventional wireless communication network, there are many differences in transmission quality depending on the state of the wireless network. In the case of non-real-time services, it is possible to minimize the influence on the state of the wireless network by using a relatively large buffer, while in the real-time service, there are many restrictions in using the buffer because of the time delay. In other words, because it uses a relatively small buffer, it is directly affected by the state of the wireless network.

If an application can receive information about changes in the wireless channel environment, it can provide high-quality multimedia services optimized for the network situation. As shown in FIG. 1, when the multimedia data is transmitted from the terminal 1 to the terminal 2, the multimedia data is transmitted through the radio section 1 and the radio section 2. In the terminal to be transmitted, the channel environment information of the wireless section 1 to which it belongs can be directly obtained, but the information of the wireless section 2 cannot be directly known. However, when the actual data is transmitted, both wireless sections are affected, so if the information on the opposite wireless section can be obtained, multimedia transmission optimized for the network may be possible.

In the case of using RTCP as a way to obtain information about the network, when using the data received through RTCP due to a long transmission cycle, the wireless channel environment may already be changed. In the case of one-to-one communication, the transmission period of the RTCP can be changed quickly by allocating a large number of bands to the RTCP transmission. However, when a large amount of radio resources are allocated to a control signal such as RTCP, limited radio resources may be wasted. In addition, an additional RTCP APP packet must be used to transmit data other than the information (packet loss rate, network jitter, time delay, etc.) to be transmitted through RTCP.

3 is a block diagram of a compound RTCP packet in a real-time bidirectional multimedia service using a conventional wireless communication network. In the case of RTCP, as shown in FIG. 3, a compound packet form of an RTCP SDES packet together to transmit an RTCP SR packet. If you use RTCP APP to transmit additional data together, more radio resources are required. In this case, duplicated contents (version, SSRC, etc.) contained in each RTCP packet may cause waste of radio resources.

Therefore, the present invention reduces the load on the limited wireless network by shortening the transmission period as much as possible and reducing unnecessary information as much as possible without violating the standard used in the real-time multimedia transmission service, and transmits information on its own wireless section to the other terminal. It is intended to provide a network context information transmission method in a real-time multimedia service using a wireless communication network.

According to an aspect of the present invention for achieving this, in a method for transmitting network context information in a real-time multimedia service using a wireless communication network, a session for transmitting channel information and data between at least one client and the server After the connection is established, a process of requesting session information from an arbitrary client, a process of checking total session information belonging to each channel of the network, and session information of the corresponding channel among the entire session information are performed. It includes the step of transmitting the session information to the requesting client by including in the packet.

According to another aspect of the present invention, in the network context information transmission apparatus in a real-time multimedia service using a wireless communication network, at least one terminal (send) to send the session information for the wireless section to which it belongs to one, At least one base station to which the at least one terminal belongs, and a base station controller to which the at least one base station belongs.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific components are shown, which are provided to help a more general understanding of the present invention, and the specific details may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau.

As mentioned in the related art, a method of obtaining information about a network using RTCP is difficult to respond to changes in the radio channel environment due to a relatively long transmission cycle, and a large amount of radio resources to control signals such as RTCP. There is a problem in that the allocation may cause waste of limited radio resources.

In the present invention, in the transmission of information on its own radio section to the other terminal using the RTP extension header, the transmission period is shortened and the waste of resources is limited without violating the standard used in the real-time multimedia transmission service. We propose a configuration to reduce the load on the wireless network. Before describing the configuration, the RTP can be represented as follows.

The server is connected through a network to collect and manage various content data, and provides a list of various multimedia contents to a client requesting the multimedia contents. When the client selects the necessary contents, the server provides the multimedia data in a download or streaming manner. .

In this case, RTP and RTCP are transmitted through UDP (User Datagram Protocol), and Real Time Streaming Protocol (RTSP) for call processing and media control is transmitted through TCP to deliver data faster but with less reliability for real-time processing of contents. do.

UDP is a datagram transmission protocol. It is connectionless and does not check for transmission errors. The advantage of UDP is that it does not check for errors, so it arrives at the other party as soon as data is sent. That is, the time delay can be reduced.

The disadvantage of UDP is that there is no error checking, so there is no way to check if it is properly transmitted to the other party. If confirmation is required, the response should be sought directly from the other party. In addition, since the routing path may change every transmission, the order of the data may change even if it arrives properly. Because of the non-connection, it is impossible to check whether the other party is connecting or disconnecting.

RTP is a protocol that complements the disadvantages of UDP and preserves the advantages. It is a protocol for transmitting data in real time. It provides a function suitable for transmitting real-time data such as audio, video, and interactive simulation. ) And time stamp. In other words, it is a protocol in which the transmitting side reproduces in order in the receiving side by additionally using the packet number and transmission time. In general, RTP is transmitted by UDP for this purpose.

In addition, it calculates the traffic level by using additional information required for the header, and if the traffic volume is large, it has some safety such as adjusting the amount of sending or compressing the data.

On the other hand, RTCP is an RTP control protocol. It records packet loss in the client that receives the data by RTP and is used to adjust the quality of service in the server so that the flow of data can be detected.

RTCP, like RTP, is sent over UDP, and the information reported by the client to the server includes packet loss, lost packets, jitter intervals, and delay with previous packets. RTSP is a communication protocol for transmitting and receiving voice and video in real time, and transmits control commands between a server and a client.

Looking at the features of RTCP, the packet structure is similar to RTP and is a protocol used with RTP to maintain the quality of service of RTP. Participants who participate in an RTP session can be identified and, in general, the amount of RTCP packets is limited to within 5%.

4 is a diagram illustrating a configuration of a Real-time Transport Protocol (RTP) packet header and an extension header used for data transmission according to an embodiment of the present invention. 4 is in the form of the RTP packet defined in the RFC3550 standard document.

First, referring to the RTP packet header of FIG. 4A, an RTP packet includes a version number indicating a version of the RTP, padding which is a bit for adjusting the size of the packet, extension bits specified when the function is expanded, and a real time. A counter indicating the number of senders involved in the transmission, a marker bit indicating the boundary of the data, a payload type indicating the type of encoding, a sequence number indicating the order of the RTP packets, and an RTP packet. A timestamp indicating this transmitted time and a synchronization source identifier (SSRC) identifying the first transmission source of the message are arranged in this order.

In the data transmission by RTP packet, this time stamp is added so that the temporal relationship between the transmitting side and the receiving side is grasped, so that effects such as delay jitter in packet transmission are suppressed and data reproduction can be performed in synchronization. Each part of the fixed header field may be represented as follows.

Version (V): 2-bit field, currently has 2 values.

Padding (P): A 1-bit field with a value of 1 indicates that the packet contains one or more padding bytes. The last padding byte indicates the number of padding bytes that should be ignored in the current packet.

Extension (X): A 1-bit field with a value of 1 means that exactly one extension header appears after the fixed header.

CSRC Count (CC): 4-bit field indicating the number of CSRC identifiers listed after the fixed header.

Marker (M): 1-bit field. The interpretation of this field is determined by the profile. This field is used to indicate important events such as frame boundaries in the packet stream. The profile may define additional indication bits or extend the PT field to eliminate the indication bits.

Payload Type (PT): A 7-bit field indicating the type of RTP payload. Concatenate the value of the payload type in the profile with the actual payload type.

Sequence Number (SN): It has a value of 1 for each RTP packet transmitted in a 16-bit field. The receiving side is used to detect packet loss or to order the packets. The initial value is set randomly for security.

Timestamp: This is a 32-bit field that indicates the sampling instant of the first byte of the RTP data packet. The frequency of the clock depends on the data format of the payload and is statically specified in the profile or payload format document that defines the format. The initial value is set to a random number like the sequence number.

Synchronization Source (SSRC) Identifier: A 32-bit field that indicates the synchronization source. This value is chosen randomly so that no two or more synchronization sources with the same SSRC appear within the same RTP session.

In this case, when the extension bit X (extension bit) designated at the function extension is set to 1, an extension header as shown in FIG. 4B is added immediately after the RTP header. The extended header is implemented with a length and a value defined according to a 16 bit profile. The reason why extension headers can be added is that RTP is designed to provide the information required by a specific application so that the processing of the protocol can be integrated into the application's processing. This is because it is a kind of custom protocol that can be changed or added to make it a protocol that suits your application. The location where the extension header is added is located after the SSRC, or after the CSRC if a CSRC (Contributing Source) exists.

By using the RTP extension header as described above, information on the wireless network can be quickly transmitted while reducing the load on the limited wireless network. An embodiment of including an extension header in a multimedia service using the characteristics of the RTC is shown in FIG. 5.

5 is a block diagram of an RTP packet header including an extension header in a real-time bidirectional multimedia service using a wireless communication network according to an embodiment of the present invention. A detailed description will be given of the necessary elements for minimizing radio resource waste and a method of shortening a transmission period through FIG. 5.

Looking at the configuration of the extended header in the RTP packet header including the extended header, the desired value can be used for the Defined by profile, and length uses the required length in units of 4 bytes as specified in the IETF RFC3550 standard. For example, if the extended header portion used is 16 bytes, the length becomes 4. (16bite / 4bite = 4) The information on the wireless network includes information about an error occurring in the wireless channel and a base station by another user. Information about congestion is needed. In the present embodiment, a parameter such as interarrival jitter, packet lost, download data rate, and delay is described as follows according to the embodiment of FIG. 5.

Error that occurs in the network: Packet lost.

Congestion degree of network: Predictable by interarrival jitter and delay information.

Data rate that can be transmitted in the network: For example, when data is transmitted from the terminal 1 to the terminal 2, the data rate that can be transmitted can be known by transmitting the download data rate to the terminal 1 in the wireless network to which the terminal 2 belongs.

Among the parameters, interarrival jitter, delay, and packet lost are radio channel information used for RTCP transmission, and parameters such as download data rate are parameters specific to RTP radio networks. In the case of RTP radio network-specific parameters, such parameters cannot be used for RTCP transmission. However, carrying information in the extension header of the RTP header is not inconsistent with the standard used, so that necessary information can be quickly delivered.

The parameters may vary depending on the environment of the wireless communication network and the nature of the data to be transmitted. In the following, the transmission using RTP including the extension header is shown in the flowchart of FIG. 6.

6 is a schematic flowchart of a transmission cycle of an RTP including an extension header in a real-time bidirectional multimedia service using a wireless communication network according to an embodiment of the present invention. 6 illustrates an embodiment of data transmission from an arbitrary client to another arbitrary client, and thus, using the configuration diagram of FIG. 1 as an example, a flow of transmitting channel environment information of a wireless section of a counterpart from another terminal to another terminal is shown. It demonstrates with the flowchart of FIG.

Referring to the flowchart of FIG. 6, first, in step 602, channel environment information, that is, information on a wireless section, is requested from an arbitrary client in order to transmit / receive data with a counterpart. Based on the requested information in step 604, the entire channel environment information belonging to each channel of the network is checked and then transmitted to the corresponding base station. In step 606, the base station injects the requested channel environment information into the extension header of the RTP packet header and sends it to the control station. In step 608, the control station transmits the RTP packet to the base station including the client requesting the information. In step 610, the channel environment information injected from the base station receiving the RTP packet is extracted. In step 612, the base station provides the extracted channel environment information to the client requesting the information, and optimized multimedia transmission is possible based on the channel environment information.

When the wireless network data is transmitted using the RTP extension header, there are advantages as described below.

First, compatibility is ensured in communication with a terminal that does not use an extended header. Of course, when the extended header is not used, the multimedia information optimized for the network situation is not possible in the application program because the information on the network condition is not received, but it is not a problem in the actual data transmission. If the information on the wireless network is loaded in the RTP payload part, transmission is possible in the same transmission period as claimed in this patent, but it is not compatible with other terminals that do not use the patent.

Next, there is a minimization of radio resource waste due to faster transmission period and unnecessary information transmission restraint compared to RTCP. By sending information about RTP packets that are periodically transmitted, they have a faster period than RTCP.

When RTCP is used to send wireless network information, multiple RTCP packets (RTCP SR, RTCP SDES, RTCP APP, etc.) must be transmitted in compound form, resulting in a waste of limited radio resources because each packet is redundant. In contrast to the RTCP, this patent minimizes waste of radio resources by excluding unnecessary matters.

In addition to the parameters used in the embodiment of the present invention, various other parameters may be used as needed, and the number and order of bytes used in the used parameters may also be used differently.

As described above, the configuration and operation of a network condition information transmission method may be performed in a real-time multimedia service using a wireless communication network according to an embodiment of the present invention. Meanwhile, in the above description of the present invention, specific embodiments have been described. Modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but by the claims and equivalents of the claims.

As described above, according to the present invention, in the real-time multimedia service using the wireless communication network, the network situation information transmission method transmits the information about the wireless network to the RTP packet periodically transmitted without violating the standard used, thereby providing a faster period than the RTCP. When RTCP is used, a packet is transmitted in a compound form, resulting in a waste of limited radio resources. In the present invention, radio resource waste is minimized by excluding redundant matters.

Claims (10)

A method for transmitting network status information in a real time multimedia service using a wireless communication network, A process of establishing a session connection for transmitting channel information and data between at least one client and the server and receiving session information from an arbitrary client; Checking total session information belonging to each channel of the network; And transmitting session information of the corresponding channel among the entire session information in a Real-time Transport Protocol (RTP) packet and transmitting the session information to the requesting client. The method of claim 1, Method of transmitting network status information in a real-time multimedia service, characterized in that the session information of the servers connected to the network is included in the RTP packet. The method of claim 1, wherein the transmitting of session information of the corresponding channel is performed. Transmitting the wireless channel information and the data packet together in the real-time multimedia service; And providing a multimedia service optimized for a wireless network environment using the information. The method of claim 1, wherein the session information of the corresponding channel is Method for transmitting network status information in a real-time multimedia service, characterized in that the transmission via the RTP data packet. The method of claim 1, wherein the RTP packet is When the extension bit in the RTP header is set to 1, the RTP extension header is added to the RTP header. The process of claim 1, wherein the session information is included in the RTP packet and transmitted. And transmitting the extended header added to the RTP packet including the session information to the client requesting the session information. 7. The method of claim 6, wherein the session information included in the RTP extension header is A method for transmitting network condition information in a real-time multimedia service, comprising: radio channel information, a parameter used for RTCP control and a parameter specific to a wireless network that cannot be used for RTCP transmission. 8. The method of claim 7, wherein said parameter is Depending on the nature of the wireless network and the real-time multimedia service used, and using parameters Includes the number and order of bytes of parameters used can be changed to suit their characteristics, Method for transmitting network status information in a real-time multimedia service, characterized in that to obtain information about the network required as the parameter. An apparatus for transmitting network condition information in a real-time multimedia service using a wireless communication network, At least one terminal to send the session information about the radio section to which it belongs to the base station to which it belongs, At least one base station to which the at least one terminal belongs, And a base station controller to which the at least one base station belongs. The method of claim 9, wherein the base station Apparatus for transmitting network status information in a real-time multimedia service, characterized in that for transmitting the session information for the wireless section received from the terminal via a control station to the base station to which the requesting information belongs via the RTP data packet.

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