Background technology
CMMB is the mobile TV technology of China's independent research, set up the unified operating mechanism of the mobile media broadcasting network and the whole nation that covers the whole nation according to the basic principle of " world one; StarNet's combination; unified standard; whole nation roaming ", utilize ground or satellite broadcasting television nerve of a covering to mobile phone, personal digital assistant (PDA, Personal Digital Assistant), dynamic image expert compression standard audio frequency aspect 3 (MP3, MPEG AudioLayer-3), MP4, digital camera, Miniature Receive Terminal on notebook computer and the car and boat etc. provides broadcast TV program point-to-arealy.
By the end of on February 24th, 2010, the CMMB signal was opened in existing 301 cities, the whole nation, and 22 provincial administrative units have realized that the whole province is open-minded, and had 108 cities to reach the requirement of present stage degree of depth covering.At present, the city of opening the CMMB signal mainly is provincial capital, municipality directly under the Central Government and prefecture-level city, and single frequency network has been built in some of them city with good conditionsi.Here the single frequency network of being mentioned is meant the radio-transmitting station that is in synchronous regime by a plurality of different locations, at one time, and with the same signal of same frequency emission, to realize reliable covering to certain coverage.The single frequency network technology has many advantages, such as: 1), therefore can save frequency resource greatly, improve the availability of frequency spectrum owing to adopt same frequency; 2) because the characteristic of radio signal itself, in built-up city, no matter the transmitting power of single radio transmitting station is much, zones that can exist signal not cover inevitably all, the zone that these signals do not cover is called blind area or blind spot, and in the single frequency network technology, penetrates with taking place frequently by multiple spot, can solve the problem of signal coverage hole, thereby obtain coverage rate preferably; 3) by optimizing and adjustment single frequency network transmit network, as radio-transmitting station quantity, distribution and height of transmitting antenna etc., can utilize the radio-transmitting station of a plurality of smaller powers to replace a powerful radio-transmitting station, thereby reduce signal radiation, reduce electromagnetic wave and pollute and strengthen and cover the uniformity, and can adjust at any time as required and cover intention.
At present, single frequency network has not only been set up in existing a few cities such as Beijing, and districts (this class city can be called the key city) such as Changping, Tongzhou around having covered, and the program that district receives around these is the same with the program that Beijing City receives.Current, the program that the CMMB technology provides mainly comprises the programs that programs that 5 cover TV programme that central authorities provide and 2 cover audio broadcasting programs, province provide and city provide, and below abbreviates central program, province's program and city's program respectively as.Along with the continuous development of CMMB technology and deeply, each district also has the demand that increases this district program.
In the prior art, RTP (the RTP that the encoded back of central authorities' program produces, Real-timeTransport Protocol) flowing through after the packing via satellite, the mode with the Internet Protocol (IP OVERDVB) of digital video broadcasting is sent to each city, after each city receives, be reduced to rtp streaming and send to local multiplexer multiplexing, multiplexing with sending to local multiplexer behind the local program coding simultaneously, local multiplexer to each the road signal that receives carry out multiplexing after, obtain multiplexing code stream, and the multiplex stream (PMS of utilization packing, Packetized Multiplexing Stream) bag carries, mode by PMS OVER ASI sends to modulator and modulates, and then is transmitted to each receiving terminal by the radio-transmitting station.
According to above-mentioned introduction as can be known, if local program is wished to increase in each district, so with central program, after province's program and city's program (higher level city program under each district) are multiplexing, also need the further multiplexing local program of going up, output to modulator then and then launch by the radio-transmitting station, and central program, province's program and city's program transmission have different propagation delay times during to each district, the implementation that the multiplexer of different production firms carries out when multiplexing is also different, promptly there is multiplexing time delay, will cause a plurality of radio-transmitting stations in the single frequency network can not broadcast homologous programs synchronously like this, here the homologous programs of being mentioned, promptly refer to identical program, as all receiving program C on A ground and B ground, then program C is a homologous programs with respect to A ground and B ground, like this, for not being the non-intersection region that a plurality of radio-transmitting stations signal can both cover, though do not have any influence, but, the intersection region that can both cover for a plurality of radio-transmitting stations signal, because homologous programs fails to broadcast synchronously, therefore a plurality of signals just will disturb each other, thereby cause receiving terminal normally not receive and broadcast program.
Summary of the invention
In view of this, technical problem to be solved by this invention is to provide a kind of implementation method of Mobile Multimedia Broadcasting CMMB technology, can realize the synchronous broadcast of homologous programs in the signal cross overlay area in the single frequency network.
Another technical problem to be solved by this invention is to provide a kind of realization system of Mobile Multimedia Broadcasting CMMB technology, can realize the synchronous broadcast of homologous programs in the signal cross overlay area in the single frequency network.
Another technical problem to be solved by this invention is to provide a kind of edge multiplexer, can realize the synchronous broadcast of homologous programs in the signal cross overlay area in the single frequency network.
A technical problem more to be solved by this invention is to provide a kind of modulator, can realize the synchronous broadcast of homologous programs in the signal cross overlay area in the single frequency network.
For achieving the above object, technical scheme of the present invention is achieved in that
A kind of implementation method of Mobile Multimedia Broadcasting CMMB technology comprises:
The multiplexing code stream of the per second of each edge multiplexer receiving center multiplexer output in the single frequency network is multiplexingly gone up local program, and has the multiplexing code stream of the per second of local program to send to corresponding modulators with multiplexing; Wherein, multiplexing going up before and after the local program, the date time T OD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged;
Each modulator is according to the unified single frequency network emission delay that sets in advance, and to the modulation of delaying time of the multiplexing code stream of the per second that receives, and the multiplexing code stream after will modulating sends to corresponding radio-transmitting station;
The multiplexing code stream of the per second after the modulation that each radio-transmitting station will receive is launched.
A kind of realization system of Mobile Multimedia Broadcasting CMMB technology comprises:
The edge multiplexer is used for the multiplexing code stream of the per second of receiving center multiplexer output, multiplexingly goes up local program, and has the multiplexing code stream of the per second of local program to send to modulator with multiplexing; Wherein, multiplexing going up before and after the local program, the date time T OD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged;
Described modulator is used for according to the unified single frequency network emission delay that sets in advance, and to the modulation of delaying time of the multiplexing code stream of the per second that receives, and the multiplexing code stream after will modulating sends to the radio-transmitting station;
Described radio-transmitting station, the multiplexing code stream of the per second after the modulation that is used for receiving is launched.
A kind of edge multiplexer comprises:
Multiplexing Unit is used for the multiplexing code stream of the per second of receiving center multiplexer output, multiplexingly goes up local program, and has the multiplexing code stream of the per second of local program to send to transmitting element with multiplexing; Wherein, multiplexing going up before and after the local program, the date time T OD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged;
Described transmitting element, the multiplexing code stream that is used for the per second that will receive sends to modulator.
A kind of modulator comprises:
Receiving element is used to receive the multiplexing code stream of the per second of edge multiplexer output, and sends to modulating unit; The multiplexing code stream of described per second is the multiplexing code stream behind the multiplexing upward local program of edge multiplexer, wherein, multiplexing going up before and after the local program, the date time T OD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged;
Described modulating unit is used for according to the unified single frequency network emission delay that sets in advance, and to the modulation of delaying time of the multiplexing code stream of the per second that receives, and the multiplexing code stream after will modulating sends to the radio-transmitting station.
As seen, adopt technical scheme of the present invention, the edge multiplexer is before and after multiplexing local program, the TOD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged, and, each modulator is according to the unified single frequency network emission delay that sets in advance, the multiplexing code stream of the per second that the time-delay modulation receives, like this, even have propagation delay time and multiplexing time delay, so by after the delay process, also can realize the synchronous broadcast of homologous programs, and then in the intersection region of having avoided can both covering in a plurality of radio-transmitting stations, a plurality of transmit each other disturbed, thereby causes receiving terminal can not normally receive problem with broadcast program.
Embodiment
At problems of the prior art, a kind of implementation of CMMB technology is proposed among the present invention, can be implemented in the intersection region that a plurality of radio-transmitting stations signal can both cover the synchronous broadcast of homologous programs in the single frequency network.Before introducing the specific implementation of scheme of the present invention, at first introduce the PMS bag.
According to before introduction as can be known, multiplexing code stream utilizes PMS to wrap and carries, the length of PMS bag is 188 bytes, as shown in Figure 1, Fig. 1 is the composition structural representation of existing PMS bag, as can be seen, the PMS bag is mainly by packet header, payload and fill 3 parts and form.
Wherein, the length of header part is 16 bytes, forms structure as shown in Table 1:
Grammer |
Figure place |
Identifier |
Value |
Packet header |
? |
? |
? |
Sync byte |
8 |
uimsbf |
0x47 |
The error of transmission indication |
1 |
bslbf |
0 |
The initial indication of Payload Unit |
1 |
bslbf |
0 |
Transmission priority |
1 |
bslbf |
0 |
PID |
13 |
bslbf |
0x0000~0x?1FFF |
Transmission scrambling control |
2 |
bslbf |
‘00’ |
Adaptive section control |
2 |
bslbf |
‘01’ |
Continuous counter |
4 |
bslbf |
Cycle count |
Keep |
32 |
bslbf |
? |
Device number |
16 |
uimsbf |
Code stream output equipment numbering |
Frequency point number |
8 |
uimsbf |
PMS bag corresponding modulating frequency numbering |
The bag sequence number |
16 |
uimsbf |
PMS wraps sequence number, each frequency independent loops counting |
Payload type |
16 |
uimsbf |
The type of PMS bag payload |
Payload length |
8 |
uimsbf |
The length of the payload of PMS bag is unit with the byte |
The composition structure in the packet header of table one PMS bag
" payload type " field in the table one is used to illustrate the type of payload, be in the PMS bag the payload part carrying be Time of Day (TOD, Time of Day) message, multiplexed frame description (MFD, MultiplexingFrame Description) message still are multiplexed frame data, i.e. program data.Other field and scheme of the present invention in the table one do not have direct relation, are not described.
The corresponding relation of " payload type " field and payload portion branch loaded information is as shown in Table 2:
The value of " payload type " field |
Payload portion branch loaded information |
0x1111 |
TOD message |
0x3333 |
MFD message |
0x5555 |
The multiplexed frame data |
The corresponding relation of table two " payload type " field and payload portion branch loaded information
Usually, the PMS bag that has only a carrying TOD message in the multiplexing code stream of per second, the quantity of the PMS bag of carrying MFD message then basis is decided for the number of the multiplexed frame of multiplexer configuration, specifically, for multiplexer configuration several multiplexed frames, the PMS bag of several carrying MFD message is just arranged in the multiplexing code stream of per second, a single frequency network emission delay field is arranged in MFD message, the concrete effect back extended meeting of this field is introduced in detail; The PMS bag of each carrying MFD all can corresponding a plurality of load multiplexing frame data the PMS bag.
In addition, as shown in Figure 1, the payload part of PMS bag takies the N byte, and the value of N is not a fixed value, but decides according to the byte number that payload portion branch loaded information takies, and the 172-N byte of filling part is filled to be 0 usually.
In order to guarantee the synchronous broadcast of homologous programs, in the scheme of the present invention, at the relevant multiplexing configuration parameter that keeps homologous programs, as service identification, the multiplexed frame sign, the multiplexed sub frame sign, take time slot, modulation system, the RS coding, interlace mode and low density parity check code (LDPC, Low Density Parity CheckCode) etc. under the constant prerequisite, in any one second multiplexing code stream before and after adding local program, the audio/video frames data of TOD message and homologous programs all can not change, and, when the multiplexing code stream of modulate emission per second, need to adopt unified single frequency network emission delay.
For make technical scheme of the present invention clearer, understand, below with reference to the accompanying drawing embodiment that develops simultaneously, scheme of the present invention is described in further detail.
Fig. 2 is the flow chart of the inventive method embodiment.As shown in Figure 2, may further comprise the steps:
Step 21: the multiplexing code stream of the per second of each edge multiplexer receiving center multiplexer output in the single frequency network, multiplexingly go up local program, and have the multiplexing code stream of the per second of local program to send to corresponding modulators multiplexing; Wherein, multiplexing going up before and after the local program, the TOD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged.
Single frequency network is arranged and covered the key city in peripheral district for construction, its multiplexer can be described as the center multiplexer, the multiplexing code stream of the per second of center multiplexer output is transferred to the multiplexer in each district, usually, the multiplexer in each district is called the edge multiplexer, the edge multiplexer will be on further multiplexing on the multiplexing code stream of the per second that receives local program, be the TV programme and/or the audio broadcasting program in each district oneself, and have the multiplexing code stream of the per second of local program to send to corresponding modulators multiplexing.
Center multiplexer and edge multiplexer are different on realization mechanism: what the center multiplexer was imported mainly is IP traffic, comprise rtp streaming, data broadcasting, urgent broadcast and electronic service guidebooks (ESG, Electronic Service Guide) User Data Protocol (UDP, User Datagram Protocol) stream etc., as long as and the input of edge multiplexer comes from the multiplexing code stream of the per second that utilizes PMS to wrap to carry of center multiplexer output, the edge multiplexer is resolved the multiplexing code stream of the per second that receives, keep and wherein carry TOD message, MFD message and carry central program, the PMS bag of province's program and city's program data, replace or increase the PMS bag of carrying local program data in the good position of planning, for ESG information relevant and time slot (TS with local program, Time Slot) control information in 0 etc., can be by key city unified planning and configuration, specific implementation is a prior art, repeats no more.
According to introduction before as can be known, in the scheme of the present invention, under the constant prerequisite of the relevant multiplexing configuration parameter that keeps homologous programs, in the multiplexing code stream of the per second of local program front and back, the audio/video frames data of TOD message and homologous programs all can not change on multiplexing.
For instance, for homologous programs A, its relevant multiplexing configuration parameter remains unchanged before and after the local program on multiplexing, be: service identification is 601, multiplexed frame sign 1, multiplexed sub frame sign 0, use 3,4,5,6 time slots, Quadrature Phase Shift Keying (QPSK, Quadrature Phase Shift Keying) modulation system, RS (240,192) coding, interlace mode 3 and 1/2LDPC, not multiplexing going up before the local program, the a certain second that the edge multiplexer receives, the TOD message that is assumed to be in the N multiplexing code stream of second is 12: 30: 11 on the 14th April in 2010, format record according to TOD message is 0x0100010004010203000101, wherein, the frame of video of the homologous programs A of encapsulation is Va-Vb, audio frame is Ac-Ad, multiplexing going up after the local program, and the TOD message in the multiplexing code stream of this N second still is 12: 30: 11 on the 14th April in 2010, the frame of video of the homologous programs A of encapsulation still is Va-Vb, and audio frame still is Ac-Ad.
Step 22: each modulator is according to the unified single frequency network emission delay that sets in advance, and to the modulation of delaying time of the multiplexing code stream of the per second that receives, and the multiplexing code stream after will modulating sends to corresponding radio-transmitting station; The multiplexing code stream of the per second that receives is launched in each radio-transmitting station.
In this step, at each modulating time A, each modulator calculates the difference of modulating time A and single frequency network emission delay, described single frequency network emission delay is the single frequency network emission delay that is carried in the MFD message, then, the TOD message multiplexing code stream identical that wherein carry of each modulators modulate with this difference.
For instance, modulating time A, be to be 12: 30: 13 on the 14th April in 2010 current time (gps time), on this time basis, deduct the single frequency network emission delay, supposing to set in advance the single frequency network emission delay is 2 seconds, obtaining result of calculation is 12: 30: 11 on the 14th April in 2010, is the multiplexing code stream in 12: 30: 11 on the 14th April in 2010 in modulation 12: 30: 13 on the 14th April in 2010 TOD message so then.
Usually, the total time that propagation delay time adds multiplexing time delay probably is about 1 second, so the single frequency network emission delay is set to get final product in 2 seconds, certainly, also can be set to other value, such as 3 seconds, 4 seconds, because delay time adds total time of multiplexing time delay greater than propagation delay time, therefore, when delaying time modulation, it is the multiplexing code stream in 12: 30: 11 on the 14th April in 2010 that each modulator has all received TOD message, so can guarantee the synchronous broadcast of homologous programs.
Based on such scheme, Fig. 3 is the composition structural representation of system embodiment of the present invention.As shown in Figure 3, comprising:
Edge multiplexer 31 is used for the multiplexing code stream of the per second of receiving center multiplexer output, multiplexingly goes up local program, and has the multiplexing code stream of the per second of local program to send to modulator 32 with multiplexing; Wherein, multiplexing going up before and after the local program, the TOD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged;
Modulator 32 is used for according to the unified single frequency network emission delay that sets in advance, and to the modulation of delaying time of the multiplexing code stream of the per second that receives, and the multiplexing code stream after will modulating sends to radio-transmitting station 33;
Radio-transmitting station 33, the multiplexing code stream that is used for the per second that will receive is launched.
Wherein, described single frequency network emission delay need add multiplexing time delay sum greater than propagation delay time, such as, it probably is about 1 second that propagation delay time adds multiplexing time delay sum, the single frequency network emission delay can be set to 2 seconds, 3 seconds or 4 seconds so.
Fig. 4 is the composition structural representation of edge multiplexer embodiment of the present invention.As shown in Figure 4, comprising:
Multiplexing Unit 41 is used for the multiplexing code stream of the per second of receiving center multiplexer output, multiplexingly goes up local program, and has the multiplexing code stream of the per second of local program to send to transmitting element 42 with multiplexing; Wherein, multiplexing going up before and after the local program, the TOD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged;
Transmitting element 42, the multiplexing code stream that is used for the per second that will receive sends to modulator.
Fig. 5 is the composition structural representation of modulator embodiment of the present invention.As shown in Figure 5, comprising:
Receiving element 51 is used to receive the multiplexing code stream of the per second of edge multiplexer output, and sends to modulating unit 52; The multiplexing code stream of described per second is the multiplexing code stream behind the multiplexing upward local program of edge multiplexer, wherein, multiplexing going up before and after the local program, the TOD message of carrying in the multiplexing code stream of per second and the audio/video frames data of homologous programs all remain unchanged;
Modulating unit 52 is used for according to the unified single frequency network emission delay that sets in advance, and to the modulation of delaying time of the multiplexing code stream of the per second that receives, and the multiplexing code stream after will modulating sends to the radio-transmitting station.
Wherein, can further comprise in the modulating unit 52:
Computation subunit 521 is used for calculating the difference of described modulating time A and described single frequency network emission delay at each modulating time A, and the difference that calculates is sent to modulation subunit 522;
Modulation subunit 522 is used at each modulating time A, the TOD message multiplexing code stream identical with this difference that modulation is wherein carried.
The concrete workflow of system shown in Fig. 3~5 and device embodiment please refer to the respective description among the method embodiment shown in Figure 2, repeats no more.
In a word, adopt technical scheme of the present invention, can realize the synchronous broadcast of homologous programs in the single frequency network, and then in the intersection region of having avoided can both covering in a plurality of radio-transmitting stations, a plurality of transmit each other disturbed, thereby causes receiving terminal can not normally receive problem with broadcast program.
The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being made, is equal to replacement, improvement etc., all should be included within the scope of protection of the invention.