JP2009182417A - Communication system and video stream transmission rate control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow extending the remaining time for which a mobile communication terminal device can be driven by a battery, by reducing the power consumption of the mobile communication terminal device when receiving a video stream by the mobile communication terminal device. <P>SOLUTION: In a communication system wherein a stream distribution device for distributing video streams and the mobile communication terminal device driven by the battery are connected through a network, the mobile communication terminal includes a battery remaining capacity monitoring means for monitoring the remaining capacity of the battery and a transmission rate change requesting means for informing the stream distribution device of a request for changing a transmission rate of video streams, in accordance with the remaining capacity of the battery monitored by the battery remaining capacity monitoring means, and the stream distribution device includes a means for changing the transmission rate of video streams to the mobile communication terminal device in response to the request for changing the transmission rate, which is informed by the mobil communication terminal device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system and a video stream transmission rate control method for viewing video stream data using a battery-driven mobile communication terminal apparatus.

  In recent years, with the development of high-speed networks, viewing of video streams using these networks has increased. Most of stream distributions use protocols such as RTP (Real-time Transport Protocol), RTSP (Real-Time Streaming Protocol), and RTCP (RTP Control Protocol). By RTP and RTSP, a stream is sent from the stream distribution device to the client. The stream delivery rate is controlled according to a change in the congestion degree of the network by transmitting data and feeding back the stream reception result measured by the client to the stream delivery apparatus by RTCP.

  As a technique related to stream distribution, there are known a control method according to a line quality state for a data rate from a video stream distribution server, and a streaming data transmission method when the receiving side is a mobile terminal. For example, Patent Document 1 below discloses a method that enables transmission rate control with a fast response speed to changes in the communication environment without requiring feedback from the receiving station side on the transmitting station side of wireless communication. ing. Patent Document 2 below discloses a stream distribution system that enables stream distribution to mobile terminals without providing a care-of destination device or the like.

  However, recently, there has been a tendency to increase the number of cases where stream data is received by a battery-powered terminal such as a cellular phone or a PDA (Personal Digital Assistant), and the driving time of the mobile communication terminal device due to the battery has increased. It is desired. At the same time, there is a need to make power consumption more efficient when viewing video streams.

  However, the conventional technology does not consider power consumption when a video stream is received by a mobile communication terminal device such as a mobile phone, and there is a problem that viewing is interrupted when the battery runs out.

JP 2006-129277 A JP 2006-041819 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce power consumption in a mobile communication terminal device when a video stream is received by the mobile communication terminal device. It is an object of the present invention to provide a communication system and a video stream transmission rate control method capable of extending the remaining drivable time.

  To achieve the above object, according to the present invention, there is provided a communication system in which a stream distribution device for distributing a video stream and a mobile communication terminal device driven by a battery are connected via a network, the mobile communication The terminal device notifies the request for changing the transmission rate of the video stream to the stream distribution device in accordance with the remaining battery level monitoring means for monitoring the remaining battery level and the remaining battery level monitored by the remaining battery level monitoring means. And a transmission rate change requesting means for changing the transmission rate of the video stream to the mobile communication terminal device in response to the transmission rate change request notified from the mobile communication terminal device. A communication system is provided.

  Furthermore, according to the present invention, there is provided a video stream transmission rate control method executed in the above-described communication system.

  When a video stream is viewed using a mobile communication terminal device such as a mobile phone, a large amount of power is consumed by a device such as a processor in order to decode data. Therefore, by reducing the transmission rate of the video stream and reducing the decoding processing amount in the mobile communication terminal device, the image quality is lowered, but the remaining driveable time (battery remaining effective time) by the battery is extended. I can.

  According to the disclosed communication system and video stream transmission rate control method, the mobile communication terminal apparatus monitors the remaining battery level and dynamically controls the transmission rate of stream data from the stream distribution apparatus according to the remaining battery level. By this, it becomes possible to extend the remaining driveable time (battery remaining effective time) by the battery in the mobile communication terminal device.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a configuration example of a communication system that distributes a video stream. As shown in the figure, a mobile phone (hereinafter also simply referred to as “terminal”) 102 as a mobile communication terminal device is connected to a base station 104 via a wireless network. The base station 104 is connected to a gateway 108 via a wired network 106, and the gateway 108 is connected to a distribution server 112 as a stream distribution device via a wired network 110. Thus, the mobile phone 102 and the distribution server 112 are connected to each other via wired and wireless networks. Distribution server 112 has a function of receiving a transmission rate change request from terminal (mobile phone) 102 and changing the transmission rate in response to the request.

  FIG. 2 is a diagram illustrating a configuration example of the mobile phone 102 in FIG. In the figure, reference numeral 202 denotes an antenna, reference numeral 204 denotes a transmission circuit, reference numeral 206 denotes a reception circuit, reference numeral 208 denotes a baseband signal processing unit, reference numeral 210 denotes a control unit, reference numeral 212 denotes a speaker / microphone unit, and reference numeral 214 denotes a key input unit. Reference numeral 216 denotes a display unit (display), reference numeral 218 denotes a power supply circuit, and reference numeral 220 denotes a battery.

  Here, the baseband signal processing unit 208 performs modulation, demodulation, wireless communication control, audio processing, image processing, multimedia interface processing, and the like. The control unit 210 includes a processor, a memory, and the like, and allows the processor to execute a program stored in the memory, thereby realizing communication protocol processing, application processing, and the like, and according to the remaining amount of the battery 220, A function of notifying the distribution server 112 of a transmission rate change request is provided.

  FIG. 3 is a diagram illustrating a protocol stack implemented in an apparatus that performs transmission / reception of a stream. As shown in the figure, the terminal (mobile phone) 102 and the distribution server 112 are connected to the physical layer (L1: Layer 1) protocol, the data link layer (L2: Layer 2) protocol, and the IP (Internet Protocol) from the lower layer side. ), TCP (Transmission Control Protocol), UDP (User Datagram Protocol), RTP (Real-time Transport Protocol) / RTCP (RTP Control Protocol), RTSP (Real-Time Streaming Protocol), and the like.

  Here, in particular, RTP is a protocol intended to transfer video data, audio data, etc. in real time, and functions as an upper protocol of UDP. RTCP is a protocol used in combination with RTP to check data flow and transmit information between senders and receivers. RTSP is an application-level protocol used together with RTP / RTCP for downloading or reproducing data such as audio and moving images in real time.

  FIG. 4 is a diagram illustrating a conventional RTSP / RTP sequence example. First, to prepare for streaming, the terminal (mobile phone) 102 instructs the distribution server 112 to secure resources for stream transmission and start a session by an RTSP SETUP message (step 402). Then, a response to that is transmitted from the distribution server to the terminal (step 404).

  Next, a PLAY message by RTSP is transmitted from the terminal to the distribution server, thereby instructing the start of transmission of media data using resources secured by SETUP (step 406). Then, a response to that is transmitted from the distribution server to the terminal (step 408).

  Next, an RTP audio / video packet is transmitted from the distribution server to the terminal (step 410). Next, the reception state is notified by RTCP from the terminal to the distribution server (step 412). Then, the distribution server changes the transmission rate according to the notified reception state and then transmits the audio / video packet to the terminal again by RTP (step 414).

  Thereafter, in order to end the streaming from the terminal to the distribution server, the release of the resource and the end of the session are instructed by the RTSP TEARDOWN message (step 416). Finally, a response is transmitted from the distribution server to the terminal (step 418), and the series of sequences is completed.

  In the conventional sequence illustrated in FIG. 4, transmission rate control according to the line state is only executed, and power consumption of the terminal is not taken into consideration, and thus viewing may be interrupted due to battery exhaustion. is there.

  FIG. 5 is a sequence diagram showing the operation of the first embodiment. As in the case of FIG. 4, the basic operation is a sequence in which the distribution server prepares for transmission by the SETUP message from the terminal, starts transmission by the PLAY message from the terminal, and ends transmission by the TEARDOWN message from the terminal. Are used (steps 502, 504, 506, 508, 510, 516 and 518).

  On the other hand, in the first embodiment, the control unit 210 of the terminal 102 monitors the remaining amount of the battery 220, and when the remaining amount is equal to or lower than a preset threshold, the transmission rate is transmitted as an RTSP message. A change request is transmitted to the distribution server 112 (step 512). The distribution server 112 receives the transmission rate change request, changes the transmission rate to the requested transmission rate thereafter, and transmits the stream data to the terminal 102 (step 514).

  As described above, when the remaining amount of the battery decreases, the remaining effective time of the battery, that is, the remaining drivable time of the terminal by the battery can be extended by lowering the transmission rate of the stream data. Specifically, for example, when the remaining amount of the battery decreases to 75%, 50%, and 25%, the transmission rate can also be decreased to a transmission rate corresponding to the remaining amount of battery.

  The sequence shown in FIG. 5 shows an example in which a transmission rate change request is notified from the terminal 102 during the transmission of data from the distribution server 112. However, before the transmission of the stream is started, that is, the terminal is PLAY. A transmission rate change request may be notified before transmitting a message. Also, transmission rate control according to the line state as in the conventional sequence of FIG. 4 may be executed simultaneously. In this case, the distribution server compares the transmission rate requested according to the remaining battery level with the transmission rate according to the line status, and transmits the stream data at the lower transmission rate.

  FIG. 6 is a flowchart showing the operation of the terminal (mobile phone) 102 according to the second embodiment. 7 and 8 are diagrams respectively showing a temporary transmission rate acquisition table and a viewable prediction time acquisition table used in the processing of the terminal 102 shown in FIG. In the second embodiment, the terminal 102 has a function of accepting a user to input the scheduled viewing time of video streaming in advance, and is calculated based on the scheduled viewing time, the remaining battery level, and the current data transmission rate. The remaining drivable time of the terminal is compared. If the scheduled viewing time is longer, a transmission rate reduction instruction is transmitted to the distribution server 112, and the drivable remaining time of the terminal 102 can be extended.

  Specifically, first, the scheduled viewing time is input to the terminal 102 by the user (step 602). Then, the terminal 102 (specifically, the internal control unit 210) collects information related to the remaining amount of the battery 220, which is indicated by a percentage (step 604).

  Next, the terminal 102 refers to the temporary transmission rate acquisition table (FIG. 7) and acquires a temporary transmission rate according to the scheduled viewing time and the remaining battery level (step 606). The provisional transmission rate acquisition table (FIG. 7) is provided in the terminal 102 in advance, and the value obtained by evaluating the viewable time for each transmission rate by an experiment at the terminal manufacturer or the like is stored. ing.

  When the provisional transmission rate is determined, the terminal 102 next compares the upper limit value of the physical rate (PHY rate) of the currently connected line with the provisional transmission rate, and determines the lower rate as the requested transmission rate. (Steps 608, 610 and 612).

  Next, the terminal 102 acquires the predicted viewable time by referring to the viewable predicted time acquisition table (FIG. 8) based on the requested transmission rate and the current remaining battery level (step 614).

  Next, the terminal 102 displays the acquired predicted viewable time and the requested transmission rate (changed transmission rate) on the display unit (display) 216 of the terminal 102 as a transmission rate change notice, thereby transmitting the transmission rate to the user. (Step 616).

  After that, the terminal 102 prompts the user to allow or not to change the rate, and if permitted, sends (notifies) a transmission rate change request to the distribution server 112. If the user is not allowed, the process is terminated (steps 618 and 620).

  With the operation in FIG. 6 described above, the user of the terminal 102 can receive a video stream at an optimum data transmission rate corresponding to the scheduled viewing time.

  Regarding the above embodiment, the following supplementary notes are disclosed.

(Supplementary note 1) A communication system in which a stream distribution device for distributing a video stream and a mobile communication terminal device driven by a battery are connected via a network,
The mobile communication terminal device
Battery remaining amount monitoring means for monitoring the remaining amount of the battery;
A transmission rate change requesting means for notifying the stream distribution device of a request for changing the transmission rate of the video stream according to the remaining battery level monitored by the remaining battery level monitoring means;
Comprising
The stream distribution device
Means for changing the transmission rate of the video stream to the mobile communication terminal device in response to the transmission rate change request notified from the mobile communication terminal device;
A communication system comprising:

  (Supplementary Note 2) The transmission rate change requesting unit notifies the stream distribution device of a transmission rate change request when the remaining battery level is equal to or lower than a predetermined threshold before or during viewing of the video stream. The communication system according to attachment 1.

  (Supplementary Note 3) The transmission rate change requesting unit is configured to allow the video stream to be viewed to the end based on the scheduled viewing time and the remaining battery level input by the user before or during viewing of the video stream. The communication system according to appendix 1, wherein an optimum transmission rate is determined as a requested transmission rate.

  (Additional remark 4) The said transmission rate change request | requirement means is a communication system of Additional remark 3 which calculates viewable prediction time based on this request | requirement transmission rate and this battery remaining charge.

  (Additional remark 5) The said transmission rate change request | requirement means is a communication system of Additional remark 4 which notifies a user of this request | requirement transmission rate and this viewable prediction time as a transmission rate change advance notice.

  (Supplementary Note 6) When the transmission rate change requesting unit performs an input operation instructing permission to change the transmission rate to the transmission rate change notice, the transmission rate change request unit The communication system according to appendix 5, wherein a change request to the requested transmission rate is notified.

(Supplementary note 7) A battery-driven mobile communication terminal device connected via a network to a stream distribution device for distributing a video stream,
Battery remaining amount monitoring means for monitoring the remaining amount of the battery;
A transmission rate change requesting means for notifying the stream distribution device of a request for changing the transmission rate of the video stream according to the remaining battery level monitored by the remaining battery level monitoring means;
A mobile communication terminal apparatus comprising:

  (Supplementary Note 8) The transmission rate change requesting unit notifies the stream distribution device of a transmission rate change request when the remaining battery level is equal to or lower than a predetermined threshold before or during viewing of the video stream. The mobile communication terminal device according to appendix 7.

  (Supplementary Note 9) The transmission rate change requesting unit is configured to enable viewing of the video stream to the end based on the scheduled viewing time and the remaining battery level input by the user before or during viewing of the video stream. The mobile communication terminal apparatus according to appendix 7, wherein an optimum transmission rate is determined as a requested transmission rate.

  (Supplementary note 10) The mobile communication terminal apparatus according to supplementary note 9, wherein the transmission rate change requesting unit calculates a predictable viewable time based on the requested transmission rate and the remaining battery level.

  (Supplementary note 11) The mobile communication terminal apparatus according to supplementary note 10, wherein the transmission rate change request unit notifies the user of the requested transmission rate and the viewable prediction time as a transmission rate change notice.

  (Supplementary Note 12) When the transmission rate change requesting unit performs an input operation instructing permission to change the transmission rate to the transmission rate change notice, the transmission rate change request unit 12. The mobile communication terminal apparatus according to appendix 11, which notifies a request for change to the requested transmission rate.

(Supplementary note 13) A method for controlling a transmission rate of a video stream in a communication system in which a stream distribution device for distributing a video stream and a mobile communication terminal device driven by a battery are connected via a network,
The mobile communication terminal device monitoring the remaining battery level;
The mobile communication terminal device notifying the stream distribution device of a request for changing the transmission rate of the video stream in accordance with the monitored battery level;
The stream distribution device changing the transmission rate of the video stream to the mobile communication terminal device in response to the transmission rate change request notified from the mobile communication terminal device;
A video stream transmission rate control method comprising:

(Supplementary Note 14) In a battery-driven mobile communication terminal device connected via a network to a stream distribution device that distributes a video stream, a computer provided as a control unit is
Battery remaining amount monitoring means for monitoring the remaining amount of the battery;
A transmission rate change requesting means for notifying the stream distribution device of a request for changing the transmission rate of the video stream according to the remaining battery level monitored by the remaining battery level monitoring means;
Program to function as.

It is a figure which shows the structural example of the communication system which distributes a video stream. It is a figure which shows the structural example of the mobile telephone in FIG. It is a figure which illustrates the protocol stack mounted in the apparatus which performs transmission / reception of a stream. It is a figure which shows the example of the conventional RTSP / RTP sequence. It is a sequence diagram which shows operation | movement of 1st embodiment. It is a flowchart which shows operation | movement of the terminal (mobile telephone) which concerns on 2nd embodiment. It is a figure which shows a temporary transmission rate acquisition table. It is a figure which shows a viewable prediction time acquisition table.

Explanation of symbols

102 Mobile phone (mobile communication terminal)
DESCRIPTION OF SYMBOLS 104 Base station 106 Wired network 108 Gateway 110 Wired network 112 Distribution server 202 Antenna 204 Transmission circuit 206 Reception circuit 208 Baseband signal processing part 210 Control part 212 Speaker / microphone part 214 Key input part 216 Display part 218 Power supply circuit 220 Battery

Claims (2)

A communication system in which a stream distribution device for distributing a video stream and a mobile communication terminal device driven by a battery are connected via a network,
The mobile communication terminal device
Battery remaining amount monitoring means for monitoring the remaining amount of the battery;
A transmission rate change requesting means for notifying the stream distribution device of a request for changing the transmission rate of the video stream according to the remaining battery level monitored by the remaining battery level monitoring means;
Comprising
The stream distribution device
Means for changing the transmission rate of the video stream to the mobile communication terminal device in response to the transmission rate change request notified from the mobile communication terminal device;
A communication system comprising: A method for controlling a transmission rate of a video stream in a communication system in which a stream distribution device for distributing a video stream and a mobile communication terminal device driven by a battery are connected via a network,
The mobile communication terminal device monitoring the remaining battery level;
The mobile communication terminal device notifying the stream distribution device of a request for changing the transmission rate of the video stream in accordance with the monitored battery level;
The stream distribution device changing the transmission rate of the video stream to the mobile communication terminal device in response to the transmission rate change request notified from the mobile communication terminal device;
A video stream transmission rate control method comprising:

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