CN101442356A - Encapsulation for distribution data of mobile multimedia broadcast satellite and matching for transmission rate thereof - Google Patents
Encapsulation for distribution data of mobile multimedia broadcast satellite and matching for transmission rate thereof Download PDFInfo
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Abstract
The invention provides a distribution data encapsulation and transmission rate matching method for a mobile multimedia broadcast satellite distribution system. Symbolic data on a frequency point in a time slot is taken as a transmission unit and a distribution data packet, the distribution data packet is transmitted in the form of a transmission frame, the method takes the symbol byte count in the distribution data packet in a modulation mode of narrowest bandwidth and least symbol transmission quantity as one frame, and the distribution data packets in other bandwidths or modulation modes are integer times of one frame; data in one frame is encapsulated into the distribution data packet with a preset format, and is encapsulated to form an initial distribution data packet and a plurality of data distribution transmission packets; according to the selected bandwidth, each distribution data packet is encapsulated into a series of distribution transmission packets with the transmission frame as the unit, wherein the distribution data packets are orderly encapsulated into the distribution transmission packets according to sequences of time slots and frequency points. Then the transmission rate matching is performed to the encapsulated data.
Description
Technical Field
The invention relates to a transmitting terminal of a mobile multimedia broadcasting satellite distribution system, in particular to a distribution data packaging and transmission rate matching method of the mobile multimedia broadcasting satellite distribution system.
Background
The mobile multimedia broadcasting system provides the multimedia digital video, audio and data service broadcasting service which covers a large range and supports high-quality fixed or mobile reception for users in the frequency range of 30MHz to 3000 MHz. The program information can be transmitted in two signals: 1) the mobile multimedia modulator carries out OFDM modulation on the data subjected to channel coding, the data are directly sent to a synchronous satellite through a Ku wave band after being subjected to frequency conversion and amplification, and then the satellite forwards an OFDM signal to an S wave band to carry out large-area broadcast coverage on the ground; 2) meanwhile, the data after channel coding is synchronously transmitted to a TDM exciter (distribution modulator), is subjected to data encapsulation format conversion and QPSK modulation (strictly following the GS/T17700 standard) and is subjected to time synchronization information insertion, and is subjected to frequency conversion to a Ku waveband to be transmitted to a synchronous satellite. The ground transponder demodulates the received TDM modulation signal, performs OFDM modulation again, broadcasts on an S wave band under a specific synchronous condition, and performs supplementary coverage on a satellite direct S wave band broadcast signal.
In a satellite distribution system, a TDM exciter (distribution modulator) QPSK-modulates channel-coded data. In order to match the channel coded data to the TDM modulation transmission bandwidth of the satellite Ku band, data encapsulation and rate adaptation are required in the TDM exciter. Meanwhile, transmission auxiliary information also needs to be added into the adapted data so as to facilitate the ground forwarding station to receive and forward signals.
Disclosure of Invention
One of the objectives of the present invention is to provide a distribution data encapsulation method for a mobile multimedia broadcasting satellite distribution system.
Another object of the present invention is to provide a transmission rate matching method for a mobile multimedia broadcasting satellite distribution system.
According to the invention, a distribution data encapsulation method of a mobile multimedia broadcasting satellite distribution system is provided, wherein a mobile multimedia broadcasting system provides that 1 second signals are divided into a preset number of time slots, different modulation modes can be adopted in each time slot, multimedia broadcasting is transmitted in different bandwidths, different bandwidths correspond to different numbers of frequency points, symbol data on one frequency point in one time slot is used as a transmission unit and used as a distribution data packet, and the distribution data packet is transmitted in a transmission frame mode, the method comprises the following steps: determining the data quantity of a transmission frame, and taking a distribution data packet under a modulation mode with the narrowest bandwidth and the least symbol quantity for transmission, namely the number of symbol bytes in a time slot of a single frequency point as a frame, and the distribution data packet under other bandwidths or modulation modes, namely the number of symbol bytes in a time slot of a single frequency point as an integral multiple of the frame; encapsulating data in a frame into a distribution transmission packet with a preset format, encapsulating the data of each frame into an initial distribution transmission packet and a plurality of data distribution transmission packets, wherein the initial distribution transmission packet comprises a packet header, a distribution data frame header and a distribution data group, and each of the plurality of data distribution transmission packets comprises a packet header and a distribution data group; and according to the selected bandwidth, packaging each distribution data packet, namely data transmitted by a single frequency point in the same time slot into a series of distribution transmission packets by taking a transmission frame as a unit, wherein each distribution data packet is packaged into the distribution transmission packets in sequence according to the sequence of the time slot and the frequency point, and different data distribution packets have different numbers of transmission frames.
In the distribution data encapsulation of the invention, the distribution transmission packets conform to the GB/T17975.1 standard, and each distribution transmission packet comprises 188 bytes, including a 5-byte distribution transmission packet header and a 183-byte data field; wherein the method forms an initial distribution transport packet having the following fields: the packet header is 5 bytes, and the distribution transmission packet header occupying 5 bytes is used; a delivery header, 21 bytes, 168 bits, occupying the first 21 bytes of a 183 byte data field, the delivery header comprising: the distribution packet header information, 9 bytes, 72 bits, auxiliary transmission information, 12 bytes, 96 bits, and the distribution data group, 162 bytes, occupies the last 162 bytes of the 183 bytes of the data field, and transmits the channel-coded and interleaved mobile multimedia broadcasting data. The method also forms a data distribution transport packet having the following structure, including: the packet header is 5 bytes, and the distribution transmission packet header occupying 5 bytes is used; the distribution data group, 183 bytes, occupies a data field of 183 bytes, and transmits the mobile multimedia broadcasting data which is channel-coded and interleaved.
The method forms the packet header information of the distribution data packet in the header of the distribution data packet with the following fields: slot number, 6 bits; byte interleaver synchronization flag, 1 bit; configuration change indication, 1 bit; reserved, 8 bits; frequency point number, 8 bits; center frequency, 32 bits; signal bandwidth, 4 bits; scrambling pattern, 4 bits; mapping mode, 6 bits; reserved, 6 bits; the method forms auxiliary transmission information in a header of a distribution data frame having the following fields: modulation time, 32 bits; transmission link, 4 bits; extension segment identification, 4 bits; extension segment, 40 bits; CRC 16, 16 bits.
The modulation time field in the auxiliary transmission information is defined as a 32-bit counter and is used for identifying the transmitting time of a time slot starting point corresponding to a distribution data packet to which a current distribution data frame belongs in a ground forwarding system; the transmission link field defines the distribution mode in which the current distribution data is transmitted to the ground forwarding system, wherein a field value of 0x00 indicates that the distribution mode is a satellite, and the distribution mode corresponding to the field value of 0x01-0x0f is reserved; the type of the transmission data in the extension segment is identified in the extension segment identification field, and important transmission auxiliary information is transmitted in cooperation with the extension segment in the auxiliary transmission information, wherein the field value 0x00 of the extension segment identification field indicates that the data in the extension segment is the transmission time of a satellite uplink station distribution channel; the field value 0x01 of the extended segment identification field indicates that the data in the extended segment is the satellite uplink station broadcast channel transmission time; a field value of 0x02 of the extended segment identification field indicates that data in the extended segment is UTC time of a satellite uplink station distribution channel transmission time; a field value of 0x03 of the extended segment identification field indicates UTC time when data in the extended segment is a satellite uplink station broadcast channel transmission time; the field value of the extended segment identification field is reserved as 0x04-0x 0F; according to the content of different extension segment identifiers, various information transmitted in the extension segment is defined as: satellite distribution channel transmission time: occupying 4 bytes high in the extension section, and representing a natural time value of I, Q signals of a 1 st bit of the current 0 time slot distribution data packet after constellation mapping at the transmission moment of a satellite distribution channel, wherein the natural time is strictly aligned with UTC time; the field is defined in the 1 st distribution data frame header of the distribution data packet corresponding to each 0 time slot; satellite broadcast channel transmission time: occupying 4 bytes high in the extension section, and representing the natural time value of the symbol of the 1 st bit of the current 0 time slot distribution data packet after OFDM modulation at the transmission time of a broadcast channel, wherein the natural time is strictly aligned with the UTC time; the field is defined in the 2 nd distribution data frame header of the distribution data packet corresponding to each 0 time slot; UTC time of the satellite uplink station distribution channel transmission time: 5 bytes, the first 16 bits represent MJD date codes, the last 24 bits are encoded according to 4 bits BCD, the total 6 digits represent time accurate to second, and the time represents UTC time of I, Q signals of the 1 st bit of the current 0 time slot distribution data packet after constellation mapping at the transmission time of the satellite distribution channel; UTC time of the broadcast channel transmitting time of the satellite uplink station: the first 16 bits of the 5 bytes represent MJD date codes, the last 24 bits are encoded according to 4-bit BCD codes, the total 6 digits represent time accurate to the second, and the time represents UTC time of the 1 st bit of the current 0-slot distribution data packet at the transmission time of the symbol after OFDM modulation in the broadcast channel.
The method also forms a distribution transport packet header with the following fields: start codeword, 28 bits; packet counter, 12 bits; wherein the start codeword is defined as: the initial code value of 0x4760581 represents the initial distribution transmission packet of a series of distribution data packets; the initial code word value of 0x4720581 represents a series of data distribution transmission packets for distributing data packets; the value of the start codeword 0x4760585 indicates an adaptation packet; the value of the start codeword 0x4720585 indicates an adaptation packet; the value of the start codeword 0x471FFFF indicates that a null packet is adapted. The packet counter increments the field of each distribution transmission packet in a distribution data packet by 1, and the field of the first distribution transmission packet in the distribution data packet is set to 0x 000.
The invention solves the problems of data encapsulation and rate matching of a satellite distribution system of a mobile multimedia broadcasting system.
Drawings
Fig. 1 is a block diagram of a mobile multimedia broadcasting satellite distribution system to which a distribution data encapsulation and transmission rate matching method of the mobile multimedia broadcasting satellite distribution system of the present invention is applied;
FIG. 2 is a process showing mobile multimedia broadcast TDM modulation;
fig. 3 is a mobile multimedia broadcast distribution data structure according to the present invention;
fig. 4 shows a mobile multimedia broadcast distribution data frame and a distribution transmission packet according to the present invention.
Detailed Description
Application environment
The method for packaging the distribution data and matching the transmission rate of the mobile multimedia broadcasting satellite distribution system is applied to the mobile multimedia broadcasting satellite distribution system. Fig. 1 illustrates an example architecture 100 of a mobile multimedia broadcast satellite distribution system.
The mobile multimedia modulator 102 performs OFDM modulation on the channel-coded data, directly transmits the channel-coded data to the geostationary satellite 104 through a Ku band after frequency conversion and amplification, and then transmits an OFDM signal to an S band by the satellite to perform large-area broadcast coverage on the ground, wherein the satellite signal is received by the ground user receiver 108. Referring to fig. 1, the mobile multimedia modulator 102 includes: an LDPC channel coding device 120 for performing channel coding; an OFDM exciter 122 for OFDM-modulating the channel-coded data; the first Ku band variable frequency amplifier 124 directly transmits the OFDM-modulated signal to the geostationary satellite 104 via the Ku band after performing variable frequency amplification.
With continued reference to fig. 1, the channel encoded data is synchronously transmitted to the TDM exciter 126, converted to the Ku band by the second Ku band upconverter 128, and transmitted to the geostationary satellite 104 after data encapsulation format conversion and QPSK modulation (strictly compliant with the GS/T17700 standard). Satellite 104 transmits the TDM modulated signal directly in the Ku band to terrestrial repeater 106. The terrestrial repeater 106 demodulates the received TDM-modulated signal, performs OFDM modulation again, broadcasts on the S-band under a specific synchronization condition, and performs supplementary coverage on the satellite direct S-band broadcast signal. Terrestrial user receivers 108 receive the signals retransmitted by terrestrial repeaters 106 as a supplement to the S-band signals transmitted by satellites 104.
TDM modulation process
Fig. 2 is a flowchart illustrating a process of TDM modulation for mobile multimedia broadcasting. After receiving the distribution data, the following steps are sequentially carried out:
distribution data adaptation (step 201); data encapsulation (step 202); rate adaptation (step 203); energy diffusion (step 204); outer coding (step 205); convolutional interleaving (step 206); inner codes (step 207), respectively forming X, Y signals; the signal X, Y is constellation mapped (step 208) to form I and Q components, baseband shaped (step 209), quadrature modulated (step 210), and then radio frequency transmitted.
The present invention is concerned with step 202 data encapsulation and step 203 rate adaptation, among others.
Distributing data encapsulation
The data to be distributed comprises the data after bit interleaving of LDPC channel coding and control information. According to the mobile multimedia broadcasting system, a signal within 1 second is specified to be divided into 40 slots, each of which is 25 ms. Different modulation modes can be adopted in each time slot, including: BPSK, QPSK, 16 QAM. When interleaving bytes and bits, the time slots are also used as cyclic units. The receiver may select only signals in a particular time slot for reception in order to operate with low power consumption.
For mobile multimedia broadcasting, the total bandwidth that can be used is 25 MHz. According to the invention. In a mobile multimedia broadcasting system, two signal bandwidths are specified: 2MHz and 8 MHz. Taking into account the total bandwidth of 25MHz, different signal bandwidths will have different numbers of frequency points, the number of frequency points being 12 when the bandwidth is 2MHz, and 3 when the bandwidth is 8 MHz. According to the data structure of the OFDM modulation part of the mobile multimedia broadcast, distributed data is input according to the sequence of time slot by time slot and frequency point by frequency point, namely, the data of different frequency points in the same time slot is transmitted first, then the data of different frequency points in the next time slot are transmitted, and the sequence of the frequency points is the same. Structure of distribution data referring to fig. 3, the distribution data is in units of distribution packets. The data to be transmitted at a single frequency point in a single time slot form a distribution data packet, e.g. a distribution data packet (T)m，Fp) The data of the distribution channel required to be transmitted on the mth time slot and the pth frequency point is contained. The length of the distributed data packet is different according to the different modulation modes and the different carrier numbers of the mobile multimedia broadcasting OFDM. For example, the system simultaneously defines 3 modulation modes: BPSK, QPSK and 16 QAM. Thus, within a time slot, various modulation configurations can be configuredThe amount of data transferred is shown in the table below, i.e. the length of a single distribution packet:
table 1: symbol data amount in single time slot of mobile multimedia broadcasting system
For convenience of transmission, the invention defines a transmission frame, called a TDM frame, and the data size in one transmission frame is determined as follows, the number of symbol bytes in a time slot of a single frequency point in a modulation mode with the narrowest bandwidth and the least number of transmitted symbols, that is, the size of a single distribution data packet in the modulation mode with the narrowest bandwidth and the least number of transmitted symbols is taken as one frame, and the number of symbol bytes in a time slot of a single frequency point in other bandwidths or modulation modes, that is, the size of a single distribution data packet in other modulation modes is an integral multiple of one frame.
Referring to table 1 above, the size of a single distribution packet in the 2MHz bandwidth and BPSK modulation mode is selected as the data transmission amount of one frame, that is, one frame is 3456 bytes. Accordingly, it is possible to obtain: when the bandwidth is 2MHz, various modulation modes are adopted, and the data volume of the distributed data packet is as follows: BPSK is 1 frame, QPSK is 2 frames, 16QAM is 4 frames. At 8MHz bandwidth, the data amount of the distributed data packet is as follows: BPSK is 5 frames, QPSK is 10 frames, 16QAM is 20 frames.
For each transport frame, 3456 bytes are required to be packed into distribution transport packets for transmission, and according to the present invention, the format of the symbolic data transport package is compatible with the GB/T17975.1 standard, and according to the GB/T17975.1 standard, the size of each distribution transport packet is 188 bytes. For 3456 bytes of a frame, 19 distribution transport packets need to be used. Thus, the present invention encapsulates information data every 3456 bytes in 19 distribution transport packets: each data distribution transmission packet is 188 bytes, wherein the first 5 bytes are distribution transmission packet headers, and the remaining 183 bytes are data fields. For each transmission frame, the first of the 19 distribution transmission packets is the initial distribution transmission packet, and the last 18 are the data distribution transmission packets. The process of encapsulating the data of one distribution data packet into several transmission frames (also called distribution data frames) and further into a series of distribution transmission packets can be referred to as fig. 4.
The structure of the initial distribution transmission packet is as follows:
the packet header is 5 bytes, and the distribution transmission packet header occupying 5 bytes is used;
a distribution header, 21 bytes, 168 bits, occupying the first 21 bytes of a 183 byte data field, the distribution header further comprising: distributing packet header information, 9 bytes, 72 bits; and auxiliary transport information, 12 bytes, 96 bits;
the distribution data group, 162 bytes, occupies the last 162 bytes of the 183 bytes data field, and transmits the channel-coded and interleaved mobile multimedia broadcasting data.
The structure of the data distribution transmission packet is as follows:
the packet header is 5 bytes, and the distribution transmission packet header occupying 5 bytes is used;
the distribution data group, 183 bytes, occupies a data field of 183 bytes, and transmits the mobile multimedia broadcasting data which is channel-coded and interleaved.
Wherein, the 21-byte distribution data frame header in the initial distribution transmission packet encapsulates the distribution data packet header information and the transmission auxiliary information. Referring to the definitions in table 2, it includes the following fields:
table 2 distribution data frame header definitions
In the above-mentioned transmission auxiliary information, the modulation time field is defined as a 32-bit counter, and is used to identify the transmission time of the time slot starting point corresponding to the distribution data packet to which the current distribution data frame belongs in the terrestrial forwarding system.
The transmission link field defines the distribution mode in which the current distribution data is transmitted to the terrestrial forwarding system, and the definition is shown in table 3.
Table 3 transmission link definition table
| Field value | Mapping schema |
| 0x00 | Satellite |
| 0x01-0x0f | Retention |
The extension segment identification field identifies the type of data transmitted in the extension segment. Some important transmission auxiliary information is transmitted in cooperation with the extension segment, and the extension segment identifier is defined in table 4.
Table 4 extended segment identification definition table
| Value of | Description of the invention |
| 0x00 | Indicating that the data in the extension segment is the satellite uplink station distribution channel transmission time (100ns accuracy) |
| 0x01 | Indicating that the data in the extension segment is the satellite uplink station broadcast channel transmission time (100ns accuracy) |
| 0x02 | UTC time indicating the time when the data in the extension segment is the transmission time of the distribution channel of the satellite uplink station |
| 0x03 | UTC time indicating when data in the extension segment is broadcast channel transmission time of satellite uplink station |
| 0x04-0x0F | Retention |
According to the content of different extension segment identifiers, various information transmitted in the extension segment is defined as:
satellite distribution channel transmission time: occupies 4 bytes in the high of the extension segment, and represents the natural time value (accurate to 100ns) of the I, Q signal after the 1 st bit of the current 0 time slot distribution data packet is subjected to constellation mapping at the transmission moment of the satellite distribution channel. This natural time is aligned strictly with UTC time. This field is defined in the header of the first delivery data frame of the delivery packet corresponding to each 0 slot. Bits 0-25 represent a 100ns precision time count value, counting range 0-1 second.
Satellite broadcast channel transmission time: occupies 4 bytes in the high of the extension segment and represents the natural time value (accurate to 100ns) of the symbol of the 1 st bit of the distribution data packet of the current 0 time slot at the transmission moment of the broadcast channel after OFDM modulation. This natural time is aligned strictly with UTC time. This field is defined in the header of the second delivery data frame of the delivery packet corresponding to each 0 slot. Bits 0-25 represent 100ns precision time counts, ranging from 0-1 second.
UTC time of the satellite uplink station distribution channel transmission time: 5 bytes, the first 16 bits representing the MJD date code; the last 24 bits are encoded in 4-bit BCD, and 6 digits represent time, time and date conversion to seconds-accurate, see GY/T220.2-2006 "mobile multimedia broadcast part 2: multiplex > < appendix B. This time represents the UTC time of I, Q signal at the transmission time of the satellite distribution channel after the first bit of the current 0-slot distribution packet is constellation mapped.
UTC time of the broadcast channel transmitting time of the satellite uplink station: 5 bytes, the first 16 bits representing the MJD date code; the last 24 bits are encoded in 4-bit BCD, and 6 digits represent time, time and date conversion to seconds-accurate, see GY/T220.2-2006 "mobile multimedia broadcast part 2: multiplex > < appendix B. This time represents the UTC time of the symbol at the transmission time of the broadcast channel after the OFDM modulation of the first bit of the current 0-slot distribution packet.
Whether for the initial distribution transport packet or the data distribution transport packet, it has a 5-byte header, which occupies a 5-byte distribution transport packet header, and the packet header consists of a 28-bit start code word and a 12-bit packet counter.
Wherein, the 28-bit start code word is defined in table 5.
TABLE 5 initial code word value taking Table
| Value taking | Application field |
| 0x4760581 | First distribution transmission packet of distribution data packet |
| 0x4720581 | Other distribution transport packets of the distribution data packet |
| 0x4760585 | Adaptation bag |
| 0x4720585 | Adaptation bag |
| 0x471FFFF | Adaptive empty bag |
The packet counter increments the field by 1 for each distribution transport packet within a distribution packet. This field of the first distribution transport packet in the distribution packet is set to 0x 000.
Rate adaptation
In the TDM exciter of mobile multimedia broadcasting, the processes of energy diffusion, outer coding, convolutional interleaving and inner coding are the same as those defined in the GB/T17700 and 1999 standard for coding and modulating the satellite digital television broadcasting channel. Therefore, the transmission data after data encapsulation must be adapted in transmission rate in the form of insertion adaptation packets, so as to be able to match the satellite transmission rate defined in the GB/T17700 and 1999 satellite digital television broadcast channel coding and modulation standard. The length of the adaptive packet provided by the invention is 188 bytes, the first 28 bits are the initial code word, and the rest parts are adaptive segments.
The adaptation method comprises the following steps: when the distribution channel needs to send data packets and the distribution transmission packet of the broadcast channel is not in place, the distribution channel automatically inserts the adaptation packet for sending.
The adaptation package is defined in table 6.
Table 6 adaptive packet value taking table
| Initial codeword value | Adaptation segment value |
| 0x4760585 | Retention |
| 0x4720585 | Retention |
| 0x471FFFF | Adaptive empty bag |
Wherein, the adaptive null packet is defined as a 16-ary sequence:
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。
the invention provides a solution to the problems of data encapsulation and rate matching for satellite distribution systems of mobile multimedia broadcast systems.
Claims (10)
1. A distribution data encapsulation method of a mobile multimedia broadcasting satellite distribution system, wherein the mobile multimedia broadcasting system stipulates that 1 second signals are divided into a preset number of time slots, different modulation modes can be adopted in each time slot, the multimedia broadcasting is transmitted in different bandwidths, the different bandwidths correspond to different numbers of frequency points, symbol data on one frequency point in one time slot is used as a transmission unit and used as a distribution data packet, and the distribution data packet is transmitted in the form of a transmission frame, the method comprises the following steps:
determining the data quantity of a transmission frame, and taking a distribution data packet under a modulation mode with the narrowest bandwidth and the least symbol quantity for transmission, namely the number of symbol bytes in a time slot of a single frequency point as a frame, and the distribution data packet under other bandwidths or modulation modes, namely the number of symbol bytes in a time slot of a single frequency point as an integral multiple of the frame;
encapsulating data in a frame into a distribution transmission packet with a preset format, encapsulating the data of each frame into an initial distribution transmission packet and a plurality of data distribution transmission packets, wherein the initial distribution transmission packet comprises a packet header, a distribution data frame header and a distribution data group, and each of the plurality of data distribution transmission packets comprises a packet header and a distribution data group;
and according to the selected bandwidth, packaging each distribution data packet, namely data transmitted by a single frequency point in the same time slot into a series of distribution transmission packets by taking the transmission frame as a unit, wherein each distribution data packet is packaged into the distribution transmission packets in sequence according to the sequence of the time slot and the frequency point, and different data distribution packets have different numbers of transmission frames.
2. The distribution data encapsulation method of the mobile multimedia broadcasting satellite distribution system of claim 1,
the mobile multimedia broadcasting system stipulates that 1 second signals are divided into 40 time slots, and each time slot is 25 ms;
the multimedia broadcast includes two signal bandwidths: 2MHz for 12 frequency points and 8MHz for 3 frequency points;
the modulation mode that the multimedia broadcasting system can adopt in each time slot comprises the following steps: BPSK, QPSK, 16 QAM.
3. The distribution data encapsulation method of the mobile multimedia broadcasting satellite distribution system of claim 2,
for a 2MHz bandwidth the number of channels,
using BPSK modulation mode, the length of the distributed data packet is 27648 bits, 3456 bytes;
using QPSK modulation mode, the length of the distribution data packet is 55296 bits, 6912 bytes;
using 16QAM modulation mode, the length of the distribution data packet is 110592 bits, 13824 bytes;
for a bandwidth of 8MHz,
using BPSK modulation mode, the length of the distribution data packet is 138240 bits, 17280 bytes;
using QPSK modulation mode, the length of the distribution data packet is 276480 bits, 34560 bytes;
using a 16QAM modulation mode, wherein the length of a distribution data packet is 552960 bits and 69120 bytes;
wherein, the data amount of one transmission frame is 3456 bytes,
therefore, when the 2MHz bandwidth is adopted, the number of transmission frames corresponding to the distribution data packets adopting different modulation modes is respectively:
the BPSK modulation mode is 1 frame;
the QPSK modulation mode is 2 frames;
the 16QAM modulation mode is 4 frames;
when 8MHz bandwidth is adopted, the number of transmission frames corresponding to the distributed data packets in different modulation modes is respectively as follows:
the BPSK modulation mode is 5 frames;
the QPSK modulation mode is 10 frames;
the 16QAM modulation scheme is 20 frames.
4. The distribution data encapsulation method of the mobile multimedia broadcasting satellite distribution system of claim 3,
the distribution transmission packets conform to the GB/T17975.1 standard, and each distribution transmission packet comprises 188 bytes, including a distribution transmission packet header of 5 bytes and a data field of 183 bytes; wherein,
the method forms an initial distribution transport packet having the following fields, including:
a packet header, 5 bytes, which occupies the 5-byte distribution transmission packet header;
distributing a data header, 21 bytes, 168 bits, occupying the first 21 bytes of the 183 bytes of data field, comprising:
distributing packet header information, 9 bytes, 72 bits;
auxiliary transmission information, 12 bytes, 96 bits;
distributing data group, 162 bytes, occupying the last 162 bytes in the 183 bytes data field, and transmitting the mobile multimedia broadcast data after channel coding and interleaving;
the method also forms a data distribution transport packet having the structure comprising:
a packet header, 5 bytes, which occupies the 5-byte distribution transmission packet header;
and transmitting the channel-coded and interleaved mobile multimedia broadcasting data by using 183 bytes of data field of the distribution data group.
5. The distribution data encapsulation method of the mobile multimedia broadcasting satellite distribution system of claim 4,
the method forms distribution packet header information in a distribution data frame header having the following fields:
slot number, 6 bits;
byte interleaver synchronization flag, 1 bit;
configuration change indication, 1 bit;
reserved, 8 bits;
frequency point number, 8 bits;
center frequency, 32 bits;
signal bandwidth, 4 bits;
scrambling pattern, 4 bits;
mapping mode, 6 bits;
reserved, 6 bits;
the method forms auxiliary transmission information in a header of a distribution data frame having the following fields:
modulation time, 32 bits;
transmission link, 4 bits;
extension segment identification, 4 bits;
extension segment, 40 bits;
CRC 16, 16 bits.
6. The distribution data encapsulation method of the mobile multimedia broadcasting satellite distribution system of claim 5,
a modulation time field in the auxiliary transmission information is defined as a 32-bit counter and is used for identifying the transmitting time of a time slot starting point corresponding to a distribution data packet to which a current distribution data frame belongs in a ground forwarding system;
a transmission link field in the auxiliary transmission information defines which distribution mode the current distribution data is sent to the ground forwarding system, wherein a field value of 0x00 indicates that the distribution mode is a satellite, and the distribution mode corresponding to the field value of 0x01-0x0f is reserved;
the extension segment identification field in the auxiliary transmission information identifies the type of the transmission data in the extension segment, and transmits important transmission auxiliary information in cooperation with the extension segment in the auxiliary transmission information, wherein,
the field value 0x00 of the extended segment identification field indicates that the data in the extended segment is the satellite uplink station distribution channel transmission time;
the field value 0x01 of the extended segment identification field indicates that the data in the extended segment is the satellite uplink station broadcast channel transmission time;
a field value of 0x02 of the extended segment identification field indicates that data in the extended segment is UTC time of a satellite uplink station distribution channel transmission time;
a field value of 0x03 of the extended segment identification field indicates UTC time when data in the extended segment is a satellite uplink station broadcast channel transmission time;
the field value of the extended segment identification field is reserved as 0x04-0x 0F;
according to the content of different extension segment identifiers, various information transmitted in the extension segment is defined as:
satellite distribution channel transmission time: occupying 4 bytes high in the extension section, and representing a natural time value of I, Q signals of a 1 st bit of the current 0 time slot distribution data packet after constellation mapping at the transmission moment of a satellite distribution channel, wherein the natural time is strictly aligned with UTC time; the field is defined in the 1 st distribution data frame header of the distribution data packet corresponding to each 0 time slot;
satellite broadcast channel transmission time: occupying 4 bytes high in the extension section, and representing the natural time value of the symbol of the 1 st bit of the current 0 time slot distribution data packet after OFDM modulation at the transmission time of a broadcast channel, wherein the natural time is strictly aligned with the UTC time; the field is defined in the 2 nd distribution data frame header of the distribution data packet corresponding to each 0 time slot;
UTC time of the satellite uplink station distribution channel transmission time: 5 bytes, the first 16 bits represent MJD date codes, the last 24 bits are encoded according to 4 bits BCD, the total 6 digits represent time accurate to second, and the time represents UTC time of I, Q signals of the 1 st bit of the current 0 time slot distribution data packet after constellation mapping at the transmission time of the satellite distribution channel;
UTC time of the broadcast channel transmitting time of the satellite uplink station: the first 16 bits of the 5 bytes represent MJD date codes, the last 24 bits are encoded according to 4-bit BCD codes, the total 6 digits represent time accurate to the second, and the time represents UTC time of the 1 st bit of the current 0-slot distribution data packet at the transmission time of the symbol after OFDM modulation in the broadcast channel.
7. The distribution data encapsulation method of the mobile multimedia broadcast satellite distribution system of claim 5, wherein the method forms a distribution transport packet header having the following fields:
start codeword, 28 bits;
packet counter, 12 bits;
wherein the start codeword is defined as:
the initial code value of 0x4760581 represents the initial distribution transmission packet of a series of distribution data packets;
the initial code word value of 0x4720581 represents a series of data distribution transmission packets for distributing data packets;
the value of the start codeword 0x4760585 indicates an adaptation packet;
the value of the start codeword 0x4720585 indicates an adaptation packet;
the value of the start codeword 0x471FFFF indicates that a null packet is adapted.
The field of each distribution transmission packet in a distribution data packet of the packet counter is incremented packet by packet, the increment is 1, and the field of the first distribution transmission packet in the distribution data packet is set to be 0x 000.
8. A transmission rate matching method of a mobile multimedia broadcasting satellite distribution system, characterized in that the mobile multimedia broadcasting satellite distribution data to be transmitted is packaged according to the distribution data packaging method of any one of claims 1 to 7, wherein when the distribution channel needs to transmit the data packet and the distribution transmission packet of the broadcasting channel is not in place, the distribution channel is automatically inserted into the adaptation packet for transmission.
9. The transmission rate matching method for mobile multimedia broadcasting satellite distribution system of claim 8, wherein the adaptation packet length is 188 bytes, the first 28 bits are a start code word, and the remaining part is an adaptation segment.
10. The transmission rate matching method for a mobile multimedia broadcast satellite distribution system according to claim 9,
the value of the initial code word is 0x4760585, and the value of the adaptation section is reserved;
the initial code word value is 0x4720585, and the adaptive segment value is reserved;
the initial codeword value is 0x471FFFF, the adaptation segment value is an adaptation null packet, and the adaptation null packet is defined as a 16-system sequence: 471F FF FF 2A AE 4E 5 65 FC 19 FC 3352 DD 1C AF 3B 2 CB CA C B C BA FABA E B F CB CE B B B CD F BB A B F CB CE B AEEC BF D C F FE 1B 445F CD CB A26 FA 4C 5E 09 AB C460A 545 DF F7B 26D E B047F C167 63A C51E CF 9E 69A 43 FF 06 FF 1983C 0600 FE 665A 5C 813 BE E B F CD 1E 29 AE 91 BD 6C 8E 14 FD E630F 8195688 EBE 465F 09b 83953 DD 362D AE 3B 00.
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| CN102547375A (en) * | 2010-12-23 | 2012-07-04 | 上海讯垒网络科技有限公司 | Transmission method for quickly previewing H.264 coded picture |
| CN105606709A (en) * | 2014-11-18 | 2016-05-25 | 株式会社东芝 | Signal processing apparatus, server, detection system, and signal processing method |
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| FR2900779B1 (en) * | 2006-05-05 | 2008-10-24 | Alcatel Sa | IP ENCAPSULATION AND MODULATION EQUIPMENT FOR THE TRANSMISSION OF IP DATA PACKETS BY SYNCHRONIZING MEGA-FRAMES WITH MEGA-RAFALES |
| CN1972408A (en) * | 2006-11-30 | 2007-05-30 | 中兴通讯股份有限公司 | A data transmission method for mobile multimedia broadcasting system |
| CN1972453B (en) * | 2006-11-30 | 2012-12-05 | 中兴通讯股份有限公司 | A data flow packaging method of mobile multimedia broadcasting system |
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| CN102547375A (en) * | 2010-12-23 | 2012-07-04 | 上海讯垒网络科技有限公司 | Transmission method for quickly previewing H.264 coded picture |
| CN105659510A (en) * | 2013-07-25 | 2016-06-08 | 意大利广播电视股份公司 | System, decoder, and method for transmitting satellite signals |
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| CN105606709A (en) * | 2014-11-18 | 2016-05-25 | 株式会社东芝 | Signal processing apparatus, server, detection system, and signal processing method |
| CN105606709B (en) * | 2014-11-18 | 2019-03-29 | 株式会社东芝 | Signal processing apparatus, server, detection system and signal processing method |
| CN115021798A (en) * | 2022-06-02 | 2022-09-06 | 北京邮电大学 | Caching, communication and control method and system for multi-unmanned aerial vehicle network |
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