CN1968078A - Method for clock synchronization of mobile multimedia broadcast receiving terminal - Google Patents
Method for clock synchronization of mobile multimedia broadcast receiving terminal Download PDFInfo
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- CN1968078A CN1968078A CN 200610140682 CN200610140682A CN1968078A CN 1968078 A CN1968078 A CN 1968078A CN 200610140682 CN200610140682 CN 200610140682 CN 200610140682 A CN200610140682 A CN 200610140682A CN 1968078 A CN1968078 A CN 1968078A
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Abstract
The invention relates to a method for making the clock of mobile multimedia broadcast receiver synchronous, wherein it comprises that: when mobile multimedia broadcast system sends data, sending system time in control channel of each frame, adding one frame serial number into each frame, adding one frame sequence serial number mark into service channel of each frame; (2), when receiver receives data, obtaining one system time from the control channel of one frame, buffering said system time and correcting the terminal clock, discontinuously receiving the control channel of following frame; receiver receives and buffers the frame serial number of service channel, judging if said number is continuous with last serial number, if they are continuous, adding one frame time on the buffered system time, buffering, receiver corrects present terminal clock via buffered system time, if they are discontinuous, calculating out the difference between it and last frame serial number, obtaining new system time or receiving and processing control channel to obtain system time.
Description
Technical field
The present invention relates to Mobile Multimedia Broadcasting or field of mobile phone, relate in particular to the method that a kind of receiving terminal that makes Mobile Multimedia Broadcasting is realized the clock synchronization of real-time audio and video stream.
Background technology
In recent years, digital mobile multimedia broadcasting technology and standard evolution are rapid, for example (the digital video broadcast-handheld formula receives Ou Zhou DVB-H: Digital Video Broadcast Handheld), the MediaFLO of the U.S. (the single forward link of medium: Media Forward Link Only) and China CMMB (mobile multimedia broadcast system: China Mobile Multimedia Broadcast) etc., for its terminal use provides many service content, if advertisement, weather forecast, news, sports cast, variety, the multimedia broadcasting play, programs such as film, the user can select the business of Mobile Multimedia Broadcasting according to the hobby of oneself.
For the consideration of the reception power consumption that reduces the mobile multimedia receiving terminal, various China mobile multi-media broadcasting technologies have all adopted several different methods to reduce operating time of receiving terminal, below two kinds of methods generally adopted:
Time slicing techniques---broadcast channel has defined a kind of frame structure, and each frame is a plurality of timeslices of segmentation further, and a business is only carried on a timeslice, and like this, receiving terminal only need receive a required timeslice, and need not whole frame is received.
Control data uses different timeslices with business datum---and receiving terminal only just receives the timeslice at control data place in the case of necessary, most time is used for receiving own selected business, this can further reduce time of reception, thereby reduces the operating time of receiving terminal.This paper is called control channel with the timeslice at control data place, and the timeslice that business datum is used is called Traffic Channel.
Each professional data of multimedia broadcasting can comprise at most: three types of video, audio frequency and data, require to guarantee energy synchronous playing between receiving terminal and the transmitting system, be that clock is synchronous, also require terminal can guarantee the synchronous playing of video/audio, promptly labial is synchronous.Clock synchronization is basic functions in the multi-media broadcasting system.
In the multimedia broadcasting field, the method for existing assurance clock synchronization has 2 kinds.A kind of is TS (transport stream) agreement, constantly sends Program Clock Reference (PCR) bag by system side, allows ceaselessly position of terminal, is synchronous with the clock that guarantees terminal and the clock of system equipment.Another kind method is NTP (NTP (Network Time Protocol)), and at set intervals, for example 1 hour, server and client were done once mutual, proofreaded the time.
Above-mentioned first method is adapted at using in the circuit network, also is fit to unidirectional broadcast network and uses, and clock can guarantee very accurate, but has brought the expense of the bigger network bandwidth.Second method is adapted at using in the IP network, though very little to the expense of the network bandwidth, be not suitable for using in the radio network.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of clock synchronizing method that is adapted at using in the radio network, is reducing the clock synchronization that can realize receiving terminal when receiving terminal obtains the control data number of times again.
For achieving the above object, the present invention takes following technical scheme:
A kind of method of mobile multimedia broadcast receiving terminal clock synchronization may further comprise the steps:
(1) mobile multimedia broadcast system is when sending data, except that transmitting system in the control channel of every frame the time, also gives every frame a frame number, and in the Traffic Channel of respective frame this frame number of sign;
(2) receiving terminal is when receiving data, obtains a system time from the control channel of a frame, and this system time of buffer memory is also proofreaied and correct terminal clock, the control channel information of after this discrete reception subsequent frame; Receiving terminal receives and preserves the frame number in the Traffic Channel, and judge whether this frame number and former frame sequence number be continuous, frame number then adds the system time of buffer memory continuously after time of a frame length buffer memory again, receiving terminal is proofreaied and correct current terminal clock according to the system time of new buffer memory, discontinuously then obtain new system time, or receive again and handling control channel obtains system time by the difference of calculating with the former frame sequence number.
In the described step (1), value of mobile multimedia broadcast system regulation, frame number circulates in this setting scope, and with corresponding frame number 0 of a certain moment, the value of the frame number of later every frame all increases by 1 than former frame, restarts to circulate after overflowing next time.
In the above-mentioned steps (2), receiving terminal can regularly obtain system time from control channel and come position.
Keep identical clock between the encoder of above-mentioned mobile multimedia broadcast system, multiplexer and the broadcast transmission station, can be to same equipment the clock synchronization of these equipment, GPS for example.
The present invention is by increasing a frame number in the Traffic Channel of every frame, terminal needn't receive the control information of every frame continuously, but according to the frame number of every frame, all increase a frame length time by every frame based on the system time of former frame, as the correction time of receiving terminal time, thereby reducing the clock synchronization that has realized receiving terminal when receiving terminal obtains the control data number of times again.
Description of drawings
Fig. 1 is the simplified diagram of mobile multimedia broadcast system;
Fig. 2 is the broadcast channel frame structural representation of mobile multimedia broadcast system;
Fig. 3 is the transmission signal of system time;
Fig. 4 is the transmission signal of frame number;
Fig. 5 is the processing procedure of receiving terminal for system time and frame number.
Embodiment
Compare with analogue technique, a great advantage of digital mobile multimedia broadcasting network is exactly: under the prerequisite that satisfies professional quality of service requirement, the broadcast channel of a mobile multimedia broadcast system can be supported the transmission of a plurality of business, has improved the utilization ratio of Radio Resource so greatly.
Mobile multimedia broadcast system is made up of encoder, multiplexer, radio-frequency (RF) emission system and receiving terminal, wherein encoder is responsible for sending real-time code stream, multiplexer is responsible for data encapsulation and is established rate adaptation function, and the output of broadcast transmission station after with broadcast channel coding and modulation is given receiving terminal by the wireless electromagnetic signal.
The Mobile Multimedia Broadcasting emission system sends frame data in a frame time, transmit by on-air radio, Mobile Multimedia Broadcasting receiving system (terminal) also receives frame data in a frame time, wherein, each frame all is made up of a control channel and a plurality of Traffic Channel, control channel is used for the transmitting control data, overhead information such as system time and business configuration for example, and control channel is positioned at the beginning of a frame usually; Traffic Channel is used for transmitting the mobile multi-media broadcasting service data.
The mobile multimedia emission system has been placed on the control channel transmission with system time, every frame all has up-to-date system time to send to receiving terminal, system time is spaced apart the system-frame duration between consecutive frame, for receiving terminal provides an accurate system time, as GPS (global positioning system: time Global PositionSystem).
In mobile multimedia broadcast system, receiving terminal is not that every frame all receives and handling control channel information, first in order to save the receiving terminal power consumption, second because in every frame control channel information except system time changes, other information all are long-time constant, so accuracy for the receiving terminal system time, in every frame Traffic Channel, increase a frame number sign, frame number circulates in the setting scope in mobile multimedia broadcast system, frame number differs 1 between successive frame, the design employing of frame number is associated with system time, with corresponding frame number 0 of a certain moment, the frame number of later every frame is all carried out '+1 ' operation, restarts to circulate after overflowing next time.The every frame of receiving terminal all increases a frame length time based on the former frame system time, as the correction time of receiving terminal time.
Receiving terminal can be converted to local zone time will obtain a system time after receiving control channel after.Receiving terminal comes the position except regularly obtaining system time from control channel, and other times can be used for clock correction by the frame number that obtains each frame.
The present invention requires between encoder, multiplexer and the broadcast transmission station equipment clock that keeps identical, can be to same equipment the clock synchronization of these equipment, and GPS for example.
Below in conjunction with accompanying drawing the present invention is described in detail.
The mobile media broadcasting network system is mainly by encoder, multiplexer, broadcast transmitter and Mobile Multimedia Broadcasting receiving system (terminal) are formed, wherein encoder is responsible for sending real-time code stream, multiplexer is responsible for data encapsulation and rate adaptation function, the broadcast transmission station can be giving receiving terminal through broadcast channel coding and modulation output wireless signal, broadcast transmission station and the receiving terminal interface between the two is a wireless air interface, as shown in Figure 1, the Mobile Multimedia Broadcasting service is issued mobile multimedia broadcast receiving terminal by air interface in the mode of electromagnetic signal.
The mobile media broadcasting network system is the signal that its receiving terminal provides after multiplexing, the structure of broadcast channel frame as shown in Figure 2: in a frame, frame length is 1 second, and control channel is positioned at the stem of every frame.
In the mobile media broadcasting network system, system time all is to be sent to receiving terminal by control channel from the Mobile Multimedia Broadcasting emission system, as shown in Figure 3.
In the mobile media broadcasting network system, frame number all is to be sent to receiving terminal by Traffic Channel from the Mobile Multimedia Broadcasting emission system, as shown in Figure 4.
Fig. 5 has illustrated receiving terminal to utilize system time and frame number to carry out the processing procedure of clock correction, after the mobile multimedia broadcast receiving terminal start receives the Mobile Multimedia Broadcasting service, at first need to receive and handling control channel information, and then obtain current system time and buffer memory; System time in the control channel of after this discontinuous reception subsequent frame, but according to frame number increases the system time of a frame length time as subsequent frame with the system time of former frame.Receiving terminal receives Traffic Channel, preserve after obtaining the traffic frame sequence number, and whether the judgment frame sequence number is up-to-date, the up-to-date reception frame Traffic Channel down that then continues, otherwise whether frame number and this frame number be continuous before judging, the discontinuous difference of then calculating this frame number and former frame sequence number, with the several frame numbers of preceding frame difference, then poor several frame length time, thereby obtain new system time, or by receiving again and handling control channel obtains system time, frame number is then preserved frame number continuously, buffer memory again after the system time of buffer memory added 1 second is proofreaied and correct the current terminal system time simultaneously; Judge whether the Terminal Service receiving course finishes, and do not finish then to continue to receive frame Traffic Channel down, otherwise flow process finishes; When if the audio/video decoding of receiving terminal partly needs system time to carry out time adjustment, directly just can obtain from buffer area.
Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof, those skilled in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of claim of the present invention.
Claims (7)
1. the method for a mobile multimedia broadcast receiving terminal clock synchronization may further comprise the steps:
(1) mobile multimedia broadcast system is when sending data, except that transmitting system in the control channel of every frame the time, also gives every frame a frame number, and in the Traffic Channel of respective frame this frame number of sign;
(2) receiving terminal is when receiving data, obtains a system time from the control channel of a frame, and this system time of buffer memory is also proofreaied and correct terminal clock, the control channel information of after this discrete reception subsequent frame; Receiving terminal receives and preserves the frame number in the Traffic Channel, and judge whether this frame number and former frame sequence number be continuous, frame number then adds the system time of buffer memory continuously after time of a frame length buffer memory again, receiving terminal is proofreaied and correct current terminal clock according to the system time of new buffer memory, discontinuously then obtain new system time, or receive again and handling control channel obtains system time by the difference of calculating with the former frame sequence number.
2. method according to claim 1 is characterized in that: in the described step (1), and value of mobile multimedia broadcast system regulation, frame number circulates in this setting scope.
3. method according to claim 2 is characterized in that: system is with corresponding frame number 0 of a certain moment, and the value of the frame number of later every frame all increases by 1 than former frame, restarts to circulate after overflowing setting next time.
4. method according to claim 1 is characterized in that: in the described step (2), receiving terminal regularly obtains system time from control channel and comes position.
5. method according to claim 1 is characterized in that: keep identical clock between the encoder of Mobile Multimedia Broadcasting transmitter side, multiplexer and the broadcast transmission station.
6. method according to claim 5 is characterized in that: the clock synchronization at described encoder, multiplexer and broadcast transmission station is to same equipment.
7. method according to claim 6 is characterized in that: described equipment is GPS.
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| CNB2006101406821A CN100536385C (en) | 2006-09-29 | 2006-09-29 | Method for clock synchronization of mobile multimedia broadcast receiving terminal |
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| CN1968078A true CN1968078A (en) | 2007-05-23 |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010069155A1 (en) * | 2008-12-18 | 2010-06-24 | 大唐移动通信设备有限公司 | Method, system and apparatus for notifying network standard time information |
| WO2011015078A1 (en) * | 2009-08-03 | 2011-02-10 | 中兴通讯股份有限公司 | Method and device for adaptive clock restoration |
| CN102025712A (en) * | 2009-09-15 | 2011-04-20 | 上海华为技术有限公司 | Data updating method, device and system |
| CN102045638A (en) * | 2009-10-09 | 2011-05-04 | 中国移动通信集团公司 | Method and equipment for time synchronization |
| CN102083194A (en) * | 2009-11-30 | 2011-06-01 | 大唐移动通信设备有限公司 | Method, system and equipment for sending time information and synchronizing time |
| WO2014026323A1 (en) * | 2012-08-14 | 2014-02-20 | Nokia Corporation | Method and apparatuses for adjusting time, computer-readable storage media and a computer program product |
| CN107197190A (en) * | 2017-07-27 | 2017-09-22 | 龙迅半导体（合肥）股份有限公司 | The generation method and device of a kind of video clock |
| CN111601133A (en) * | 2019-02-21 | 2020-08-28 | 杭州海康威视数字技术股份有限公司 | Multimedia data synchronous output system and method |
| CN117295148A (en) * | 2023-11-22 | 2023-12-26 | 泉州艾奇科技有限公司 | Time synchronization method, central control host and wireless device |
-
2006
- 2006-09-29 CN CNB2006101406821A patent/CN100536385C/en not_active Expired - Fee Related
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9549294B2 (en) | 2008-12-18 | 2017-01-17 | China Academy Of Telecommunications Technology | Method, system and apparatus for notifying network standard time information |
| US20110292860A1 (en) * | 2008-12-18 | 2011-12-01 | China Academy Of Telecommunications Technology | Method, System and Apparatus for Notifying Network Standard Time Information |
| CN101754098B (en) * | 2008-12-18 | 2013-04-03 | 电信科学技术研究院 | System time notifying method, system and device |
| WO2010069155A1 (en) * | 2008-12-18 | 2010-06-24 | 大唐移动通信设备有限公司 | Method, system and apparatus for notifying network standard time information |
| WO2011015078A1 (en) * | 2009-08-03 | 2011-02-10 | 中兴通讯股份有限公司 | Method and device for adaptive clock restoration |
| CN102025712A (en) * | 2009-09-15 | 2011-04-20 | 上海华为技术有限公司 | Data updating method, device and system |
| CN102025712B (en) * | 2009-09-15 | 2013-08-07 | 上海华为技术有限公司 | Data updating method, device and system |
| CN102045638A (en) * | 2009-10-09 | 2011-05-04 | 中国移动通信集团公司 | Method and equipment for time synchronization |
| CN102045638B (en) * | 2009-10-09 | 2014-12-10 | 中国移动通信集团公司 | Method and equipment for time synchronization |
| CN102083194A (en) * | 2009-11-30 | 2011-06-01 | 大唐移动通信设备有限公司 | Method, system and equipment for sending time information and synchronizing time |
| CN102083194B (en) * | 2009-11-30 | 2014-12-03 | 电信科学技术研究院 | Method, system and equipment for sending time information and synchronizing time |
| WO2014026323A1 (en) * | 2012-08-14 | 2014-02-20 | Nokia Corporation | Method and apparatuses for adjusting time, computer-readable storage media and a computer program product |
| CN107197190A (en) * | 2017-07-27 | 2017-09-22 | 龙迅半导体（合肥）股份有限公司 | The generation method and device of a kind of video clock |
| CN111601133A (en) * | 2019-02-21 | 2020-08-28 | 杭州海康威视数字技术股份有限公司 | Multimedia data synchronous output system and method |
| CN111601133B (en) * | 2019-02-21 | 2022-07-01 | 杭州海康威视数字技术股份有限公司 | Multimedia data synchronous output system and method |
| CN117295148A (en) * | 2023-11-22 | 2023-12-26 | 泉州艾奇科技有限公司 | Time synchronization method, central control host and wireless device |
| CN117295148B (en) * | 2023-11-22 | 2024-02-23 | 泉州艾奇科技有限公司 | Time synchronization method, central control host and wireless device |
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