KR100541523B1 - Method of Controlling Channel for Providing Multimedia Contents in Mobile Communication Network - Google Patents

Abstract

The present invention relates to a channel control method for improving a network utilization efficiency by enabling selective channel connection in providing multimedia contents to a mobile communication terminal. After the session connection is made between the mobile communication terminal and the multimedia contents providing system, Receiving a session information request message from a communication terminal, transmitting, by the multimedia content providing system, session information including a channel control condition including activation RTCP channel information and an RTCP packet transmission period to the mobile communication terminal, the mobile communication terminal and the multimedia Setting up a process for transmitting multimedia content between content providing systems, transmitting multimedia content to a mobile communication terminal by a multimedia content providing system, and the mobile communication terminal being remotely controlled according to channel control conditions. Transmitting the RTCP packet to the media content providing system, transmitting the RTCP packet to the mobile communication terminal according to channel control conditions, and releasing a session between the mobile communication terminal and the multimedia content providing system according to channel control conditions. In addition, unnecessary channel usage can be reduced, and streaming control can be efficiently performed. Accordingly, error correction and content usage statistics can be calculated.

Multimedia content, RTCP channel

Description

Method of Controlling Channel for Providing Multimedia Contents in Mobile Communication Network}

1 is a view for explaining a multimedia content providing method in a mobile communication network;

2 is a diagram illustrating a protocol stack on a mobile communication terminal side for a multimedia content service;

3 is a view for explaining the structure of the RTP packet applied when providing multimedia content in a mobile communication network;

4A and 4C are diagrams for explaining an RTCP packet structure applied when providing multimedia content in a mobile communication network;

5 is a flowchart illustrating a channel control method for providing multimedia content according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: mobile communication terminal 20: base station / base station controller

30: packet data service node 40: multimedia content providing system

50: Internet 60: Content Provider Server

70: personal computer

The present invention relates to a content providing method in a mobile communication network, and more particularly, to a channel control method for improving network utilization efficiency by enabling selective channel connection in providing multimedia content to a mobile communication terminal.

Mobile communication service is expanding from voice call service to wireless internet service, and wireless internet service is evolving from text-oriented service to multimedia service according to the development of network technology such as mobile terminal and data transmission speed. The trend is.

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 that stores video media and downloads or displays them in real time regardless of time is also derived from the interactive service.

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 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.

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

However, in order to provide multimedia contents, an RTP channel is currently allocated to video basement, video enhancement, audio, and text, and an RTCP channel must also be allocated to each RTP channel. That is, as many RTCP channels are formed as the number of RTP channels. In fact, among the RTCP channels, high utilization rates are limited to video bastion channels and audio channels. Therefore, there is a problem that utilization efficiency of network bandwidth is deteriorated due to unnecessary RTCP channel (video enhancement, text channel) allocation.

For example, an RTCP packet is 80 bytes in size and transmitted every second from the multimedia contents providing system to the mobile communication terminal through four channels (video basement, video cause, audio, text), and a response thereto. Since the signal is transmitted from the mobile communication terminal to the multimedia providing system, 320 bytes of unnecessary data occupy the network every second, and this waste is repeated until the content transmission is completed.

In addition, it is necessary to control the transmission period of the RTCP packet according to the characteristics of the data transmitted through the RTP channel, but at present, such a transmission period can not be specified, so streaming control is impossible and accordingly, there is a disadvantage such as noise in image quality. have. In other words, the RTCP packet can be seen as a response signal of the mobile communication terminal to the data received through the RTP channel, but now it is not easy to control the streaming because the RTCP packet is transmitted in response to all the RTP packets. .

Disclosure of Invention The present invention has been made to solve the problems and disadvantages described above. The purpose of the present invention is to prevent waste of resources and to efficiently use network bandwidth by selectively connecting an RTCP channel when providing multimedia content in a mobile communication network. have.                         

Another object of the present invention is to determine the response state for each mobile communication terminal by controlling the transmission period of the RTCP packet to facilitate error correction when providing multimedia content and to check the content usage status.

According to an aspect of the present invention, there is provided a channel control method for providing multimedia content, the method comprising: receiving a session information request message from the mobile communication terminal after a session connection is established between the mobile communication terminal and the multimedia content providing system; Transmitting, by the multimedia content providing system, session information including a channel control condition including activated RTCP channel information and an RTCP packet transmission period to the mobile communication terminal; Performing a setup process for transmitting multimedia contents between the mobile communication terminal and the multimedia contents providing system; Transmitting, by the multimedia content providing system, the multimedia content to the mobile communication terminal; Transmitting, by the mobile communication terminal, an RTCP packet to the multimedia content providing system according to the channel control condition, and transmitting, by the multimedia content providing system, the RTCP packet to the mobile communication terminal according to the channel control condition; And releasing a session between the mobile communication terminal and the multimedia content providing system.

That is, in order to control a channel when providing multimedia content in a mobile communication network, the multimedia content providing system designates and transmits an activation channel type and a packet transmission period in a session information transmission (DESCRIPTION response) to a mobile communication terminal. For this purpose, a field called 'a = X-RTCPcfg' can be defined and used, and the active channel type is indicated by, for example, a separator ';', and the transmission period and the transmission interval are designated to the mobile communication terminal. By transmitting, the mobile communication terminal activates the corresponding channel and transmits the RTCP RR packet and the RTCP SR packet at designated intervals every designated transmission period.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 4 are shown for understanding the present invention and the scope of the present invention should not be limited thereto.

1 is a view for explaining a multimedia content providing method in a mobile communication network.

The mobile communication terminal 10 may perform voice communication through a base station / base station controller (BTS / BSC) 20 and an exchange (not shown), and connect with a data network through a packet data service node (PDSN) 30. Thus, various wireless data services can be used.

The multimedia content providing system 40 is connected to a plurality of content provider servers 60 through the Internet 50 to collect and manage various content data, and to request multimedia content through the packet data service node 30. While providing the corresponding content to the terminal 10, it is connected to the personal computer 70 to provide a wired Internet service.

When the user of the mobile communication terminal 10 accesses the multimedia contents providing system 40 through the wireless Internet, the multimedia contents providing system 40 provides a list of various multimedia contents, and when the user selects the necessary contents, the corresponding multimedia data is downloaded. Provided by the method or streaming method. At this time, RTP and RTCP are transmitted through UDP (User Datagram Protocol) for real-time processing of content, and Real Time Streaming Protocol (RTSP) for call processing and media control is transmitted through TCP.

RTP 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. It uses a packet number and a time stamp. That is, it is a protocol that the receiving side replays in order by using the packet number and transmission time additionally. In general, RTP is transmitted by UDP for this purpose.

On the other hand, RTCP is an RTP control protocol, which is used to control the quality of service in the multimedia content providing system 40 by recording packet loss in the mobile communication terminal 10 that receives the data by RTP to detect the flow of data. Do it. RTCP, like RTP, is transmitted in UDP, and information reported by the mobile communication terminal 10 to the multimedia content providing system 40 includes a packet loss amount, a lost packet count, a jitter interval, a delay time with a previous packet, and the like. . RTSP is a communication protocol for transmitting and receiving voice or video in real time, and transmits a control command between the multimedia content providing system 40 and the mobile communication terminal 10.

2 is a diagram illustrating a protocol stack of a mobile communication terminal for a multimedia content service. In the following description, a mobile communication terminal is a terminal capable of outputting multimedia data as voice and video, and refers to all portable terminals including a cellular phone, a PCS, a PDA, and the like.

As shown, the protocol stack on the mobile communication terminal side includes a physical layer, a radio link / data link layer, an IP layer and a layer for processing control signals (TCP-RTSP-application control command) and a layer for content processing (UDP). RTP / RTCP-audio data / video data / receiver report) are on the same layer.

The layer for processing the control signal uses TCP with high reliability, and the layer for content processing uses UDP for enabling real-time transmission of data. In other words, when providing multimedia content, TCP and UDP are used to properly process content data and control data. Since the mobile communication terminal supports such a protocol, it is possible to receive multimedia content from the multimedia content providing system 40 in the manner described in FIG. 1.

3 is a view for explaining the structure of the RTP packet applied when providing multimedia content in a mobile communication network.

In the figure, V represents version information and P represents padding information. When P is set, the padding octets are included at the end of the packet. X is used to extend RTP header information. If X is set, it means that an extended RTP header exists so that one extended header follows the fixed header. The CC indicates the number of CSRC identifiers in the fixed header. The CRSC serves as a source for distinguishing the RTP packet streams generated by the RTP mixer. In other words, while RTP packets are transmitted through the network, the intermediate system receives RTP packets from various sources, combines them properly, creates a new type of RTP packet, and delivers it to the next system. An intermediate system that performs this function is called an RTP mixer. do.

M is an abbreviation of Marker and defines the profile of the multimedia. It is used to distinguish between voice and image information in a packet, and PT denotes a payload type. In addition, SEQUENCE NUMBER represents the number of transport packets, which is incremented by one each time an RTP packet is transmitted, and the mobile communication terminal which receives the RTP packet detects a packet loss and restores the packet order using this field. The TIME STAMP field records the time when the first octet of the RTP packet was sampled, that is, the time at which the packet was transmitted.

The SSRC identifier field indicates an identifier of a data source such as a camera or a microphone, a content provider server, and the CSRC identifier field records an identifier for distinguishing the sources when the RTP packets are mixed in the intermediate system.

4A and 4C are diagrams for explaining an RTCP packet structure applied when providing multimedia content in a mobile communication network.

As described above, RTCP exchanges service quality information such as the number of lost packets, delay time with previous packets, jitter intervals, calculates packet transmission rate, transmits session control information, etc. In order to reflect this, a permanent transport identifier called 'CNAME' must be transmitted. For this purpose, RTCP has a structure as shown in FIG. 4A.

Referring to FIG. 4A, RTCP includes a plurality of RPCs, such as a sender report (SR), a receiver report (RR), a source description item (SDES), a canonical name (CNAME), a telephone number (PHONE), a geographic location (LOC), and a BYE. It has a packet type. In the RTCP, a plurality of packets are transmitted in a combined form as shown in FIG. 4A.

The SR is used by the multimedia content providing system 40 to inform the mobile communication terminal 10 of statistical information about data transmission and reception, and the RR is the statistical information about transmission and reception of the mobile communication terminal 10 to the multimedia content providing system 40. SDES is used to describe the source name, including the CNAME, and BYE is used to exit the RTP session.

4B shows an RTCP SR packet structure. The RTCP SR packet consists of an 8 octets header, sender information, and a report block. First, the header includes version information (V), padding information (P), report reception count (RC), packet type (PT), RTCP packet length including header and padding, and SSRC identifier. . Referring to FIG. 4B, since the current RTP version is 2 and the padding bit is '1', it can be seen that the packet includes padding. In addition, it can be seen that the number of report receptions is five times, the size of the packet type is 8 bits, the RTCP packet length is 16 bits, and the size of the SSRC identifier is 32 bits.

Next, the sender information part includes the time at which the report was sent (NTP TIME STAMP most significant word, NTP TIME STAMP least significant word), packet transmission time (RTP TIME STAMP), and RTP sender's packet count until SR packet generation. It includes the sender's octet count.

In addition, the report block portion includes the source identifier (SSRC_n), the fraction of RTP packets lost from the previous SR or RR, the cumulative number of packets lost so far, and the packet transmission / reception time. Extended highest sequence number received, jitter interval (interarrival jitter), the most recently received report information (last SR timestamp (LSR)), the time when the most recent SR packet was received and the time delay for sending the RR (( delay since last SR (DLSR))). Herein, the variation value for the packet transmission / reception time is the lowest 16 bit of the highest variation value among the received packets, and the highest lead value is the upper 16 bits. In addition, the LSR is set to 0 if no SR has been received, and the DLSR is set to 1/65536 and 0 if no SR has been received.

4C shows an RTCP RR packet structure. The RTCP SR packet consists of an 8 octets header and a report block. First, the header includes version information (V), padding information (P), report reception count (RC), packet type (PT), RTCP packet length including header and padding, and SSRC identifier. . Referring to FIG. 4C, since the current RTP version is 2 and the padding bit is '1', it can be seen that the packet includes padding. In addition, it can be seen that the number of report receptions is five times, the size of the packet type is 8 bits, the RTCP packet length is 16 bits, and the size of the SSRC identifier is 32 bits. The packet type is generally represented by 200 for an SR packet and 201 for an RR packet.

Next, the report block portion includes the source identifier (SSRC_n), the fraction of RTP packets lost from the immediately preceding SR or RR, the cumulative number of packets lost so far, and the packet transmit / receive time. Extended highest sequence number received, jitter interval (interarrival jitter), the most recently received report information (last SR timestamp (LSR)), the time when the most recent SR packet was received and the time delay for sending the RR ( (delay since last SR (DLSR))).

Herein, the variation value for the packet transmission / reception time is the lowest 16 bit of the highest variation value among the received packets, and the highest lead value is the upper 16 bits. In addition, the LSR is set to 0 if no SR has been received, and the DLSR is set to 1/65536 and 0 if no SR has been received.

In the above, the RTCP SR and the RTCP RR packet structure have been described. When the multimedia content is provided, an RTCP packet having such a structure is transmitted and received between the multimedia content providing system 40 and the mobile communication terminal 10.

5 is a flowchart illustrating a channel control method for providing multimedia content according to the present invention.

Although not shown in Fig. 5, the mobile communication terminal 10 requests connection to the base station / base station controller 20 with high-speed packet data, and then the PDSN 30, PPP, and IP are set. In this process, the PDSN 30 performs subscriber authentication and is interworked with the multimedia content providing system 40. Accordingly, a TCP session is connected between the mobile communication terminal 10 and the multimedia content providing system 40 (S101). The radio section call processing is terminated and the multimedia content related call processing is started, and the mobile communication terminal 10 requests the session information to the multimedia content providing system 40 for the multimedia content related call processing (S102). Is shown in [Table 1].

In response to such a session information request of the mobile communication terminal 10, the multimedia content providing system 40 transmits session information using SDP. At this time, the control condition of the RTCP channel is transmitted together (S103). That is, the type of the RTCP channel to be activated, the transmission period of the RTCP RR packet to be transmitted by the mobile communication terminal 10 to the multimedia content providing system 40, and the RTCP SR packet to be transmitted to the mobile communication terminal 10 by the content providing system 40. It is to set the transmission period of the transmission. To this end, in the present invention, a field 'a = X-RTCPcfg' is defined, and the types and periods of the RTCP RR and RTCP SR packets to be transmitted by the mobile communication terminal 10 to the multimedia content providing system 40 are defined in this field. It is sent along with the session information response signal.

Parameters passed to this 'a = X-RTCPcfg' field include <RTCP type>, <RTCP duration RR>, and <RTCP duration SR>, and the <RTCP type> parameter is used to actually connect only one RTCP channel among the connected RTCP channels. By deciding whether to activate, the delimiter is continuously listed as ';' to inform the mobile communication terminal 10 of the RTCP channel to be activated. There are four delimiters to determine whether to enable or disable: 'AUD' means RTCP for audio, 'BAV' means RTCP for base video, 'ENV' means RTCP for slow video, and 'TXT' means RTCP for text. do. On the other hand, <RTCPdurationSR> and <RTCPdurationRR> indicate the time interval to send the RTCP packet. The former indicates the value for RTCP / SR and the latter indicates the value for RTCP / RR. The unit is 100ms and the range is 10 to 600. , The interval is five. That is, it can be specified as 10, 15, 20, which means that an RTCP packet should be transmitted every 1000ms, 1500ms, or 2000ms.

Meanwhile, the RTCP packet should be transmitted for audio, base video, enhanced video, and text, respectively, and should be sequentially transmitted every time RTCPduration (RTCPdurationRR, RTCPdurationSR) is divided by four. That is, if the RTCPduration is 2000ms, the audio, base video, caused video, and text RTCP packets should be sent every 500ms. For example, when the multimedia content providing system 40 transmits 'a = X-RTCPcfg AUD; BAV; ENV; TXT, 40, 10' to the mobile communication terminal 10, it is used for audio, base video, and audio. When the video and text channels are activated, the transmission period of the RTCP RR packet is set to 40 and the transmission period of the RTCP SR packet is set to 10. Accordingly, the mobile communication terminal 10 activates all RTCPs and sends RTCP / RR packets evenly at intervals of 4000 ms. First, RTCP / RRs for audio are transmitted, and RTCP / RRs for base video are transmitted after 1000 ms. In addition, RTCP / RR should be sent for enhancement video after 1000ms, and finally RTCP / RR for text after 1000ms. In addition, the multimedia content providing system 40 first transmits an RTCP / SR for audio to the mobile communication terminal 10 and transmits an RTCP / SR for base video after 250 ms, and again an RTCP / SR for video caused by 250 ms. After that, it sends RTCP / SR for text after 250ms. [Table 2a] and [Table 2b] shows an example of the session information transmitted by the multimedia content providing system 40 to the mobile communication terminal 10 using the SDP in step S102, for [Table 1] Reply message.

It can be seen that 'a = X-RTCPcfg' field is added at the bottom of [Table 2b] .It is the interval of activating RTCP for audio and base video and 4000ms which is the transmission period of RTCP / RR divided by the number of active channels. RTCP / RR packet is transmitted evenly at 2000ms, which means to send RTCP / RR for audio first and RTCP / RR for Base Video after 2000ms. In addition, the RTCP / SR packet is equally transmitted at an interval of 500 ms divided by the number of active channels, that is, 1000 ms, which is the transmission period of RTCP / SR. do.

As such, after the session information is transmitted from the multimedia content providing system 40 to the mobile communication terminal 10, the mobile communication terminal 10 transmits a setup request signal to the multimedia providing system 40 (S104). The multimedia content providing system 40 transmits a response signal thereto to the mobile communication terminal (S105). Such examples are shown in [Table 3] to [Table 10]. In each table, C-> S represents a setup transmission request signal transmitted by the mobile communication terminal 10 to the multimedia content providing system 40, and S-> C indicates that the multimedia content providing system 40 is transmitted to the mobile communication terminal 10. ) Indicates a response signal to be sent.

Thereafter, the mobile communication terminal 10 transmits a reproduction request signal to the multimedia content providing system 40 (S106), and thus the multimedia content from the multimedia content providing system 40 to the mobile communication terminal 10 through the RTP channel. Is transmitted (S107). Table 11 shows examples of a reproduction request signal transmitted by the mobile communication terminal 10. Tables 12 and 13 show multimedia contents from the multimedia content providing system 40 to the mobile communication terminal 10. An example of transmission is shown.

Thereafter, when the multimedia content transmission is completed, the mobile communication terminal 10 requests the session release to the multimedia content providing system 40 (TEARDOWN request) (S108), and the multimedia content providing system 40 responds thereto ( S109) The session is terminated (S110). Table 14 and Table 15 show an example of a session release process.

In the present invention, by setting the channel information and packet transmission period that the multimedia content providing system activates to the mobile communication terminal when transmitting session information for providing multimedia content, the mobile communication terminal activates only the corresponding channel and generates an RTCP RR packet at a predetermined period. Can transmit To this end, a new field of 'a = X-RTCPcfg' can be defined and used, and valid data transmission can proceed without error by not activating unnecessary channels.

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

According to the present invention, by specifying the type of RTCP channel to be activated by the multimedia content providing system to the mobile communication terminal and the transmission period of the RTCP RR packet to be transmitted through the activated channel when transmitting session information for providing multimedia content. Unnecessary channel use can be reduced, and streaming control can be efficiently performed, and thus there is an advantage in that error correction and content usage statistics can be calculated.

Claims (8)

A channel control method in a case where the multimedia content providing system provides multimedia content to the mobile communication terminal, including a mobile communication terminal and a multimedia content providing system connected to a mobile communication network, Receiving a session information request message from the mobile communication terminal after a session connection is established between the mobile communication terminal and the multimedia contents providing system; Transmitting, by the multimedia content providing system, session information including a channel control condition including activated RTCP channel information and an RTCP packet transmission period to the mobile communication terminal; Performing a setup process for transmitting multimedia contents between the mobile communication terminal and the multimedia contents providing system; Transmitting, by the multimedia content providing system, the multimedia content to the mobile communication terminal; Transmitting, by the mobile communication terminal, an RTCP packet to the multimedia content providing system according to the channel control condition, and transmitting, by the multimedia content providing system, the RTCP packet to the mobile communication terminal according to the channel control condition; And Releasing a session between the mobile communication terminal and the multimedia content providing system; Channel control method for providing multimedia content in a mobile communication network comprising a. delete According to claim 1, The RTCP packet transmission period includes an RTCP RR packet transmission period transmitted by the mobile communication terminal to the multimedia content providing system and an RTCP SR packet transmission period transmitted by the multimedia content providing system to the mobile communication terminal. Channel control method for providing multimedia content in a mobile communication network. The method of claim 3, wherein The transmission interval of the RTCP RR packet is a result of dividing the RTCP RR packet transmission period by the number of activation channels, and the transmission interval of the RTCP SR packet is a result of dividing the RTCP SR packet transmission period by the number of activation channels. Channel control method for providing multimedia content in the mobile communication network. According to claim 1, The RTCP channel includes an audio channel, a base video channel, an enhanced video channel, a text channel, The RTCP packet is a control packet for the multimedia content transmitted through each channel, including the RTCP RR transmitted from the mobile communication terminal and the RTCP SR packet transmitted from the multimedia content providing system. Channel control method for providing multimedia content. The method of claim 5, The active RTCP channel information includes at least one of the audio channel, the base video channel, the caused video channel, and the text channel. The method of claim 5, The active RTCP channel type is a channel control method for providing multimedia content in a mobile communication network, characterized in that it is specified by distinguishing. According to claim 1, The control condition is a channel control method for providing multimedia content in a mobile communication network, characterized in that for transmitting the session information specified in the a = X-RTCPcfg field.

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