CN101114899A - Beacon transmitting method in mobile multimedia broadcasting system - Google Patents
Beacon transmitting method in mobile multimedia broadcasting system Download PDFInfo
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- CN101114899A CN101114899A CNA2007101178355A CN200710117835A CN101114899A CN 101114899 A CN101114899 A CN 101114899A CN A2007101178355 A CNA2007101178355 A CN A2007101178355A CN 200710117835 A CN200710117835 A CN 200710117835A CN 101114899 A CN101114899 A CN 101114899A
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Abstract
The invention discloses a beacon sending method of a mobile multimedia broadcast system and the beacon comprises a synchronous signal sequence. The method comprises the following steps that: (1) The synchronous signal sequence is generated; (2) Some of a continuous sequence is selected from an endposition of the synchronous signal sequence towards the front direction and is copied as a first cyclic prefix sequence; (3) According to the first cyclic prefix sequence, a second cyclic prefix sequence is gotten and a fixed corresponding relationship is formed between the second cyclic prefix sequence and the first cyclic prefix sequence; (4) When a beacon signal is transmitted, firstly the second cyclic prefix sequence is transmitted then the first cyclic prefix sequence and finally the synchronous signal sequence is transmitted. The beacon signal method of the invention increases the exactness of an initial synchronization and improves a searching range of a channel time domain impulsion response. When the channel time domain impulsion response is acquired, the invention can solve the problem that a larger wireless channel extends for a channel delay.
Description
Technical Field
The invention relates to the technical field of mobile multimedia broadcasting, in particular to a beacon sending method in a mobile multimedia broadcasting system.
Background
In a mobile multimedia broadcasting system, a transmitter often sends a beacon signal, and then a receiver can detect the initial position of the beacon through autocorrelation operation to obtain initial synchronization; next, the local beacon sequence and the received beacon sequence are used for performing cross-correlation operation to obtain the time domain impact response of the channel.
In the mobile multimedia broadcasting industry standard GY/T220.1-2006 promulgated by the China national broadcast film television Master, a beacon signal transmitted by a transmitter has a specific structure.
Referring to fig. 1, a schematic diagram of an application of a conventional beacon structure in the GY/T220.1-2006 standard is shown. Wherein, the beacon comprises two synchronization Signal (SYNC) sequences, and the two parts are identical, and the time length is 204.8 microseconds. The SYNC signal sequence is a time-domain band-limited signal sequence.
In the GY/T220.1-2006 technical standard, the generation process of the synchronization signal sequence is as follows:
synchronization signal S b (T) is a band-limited pseudorandom signal having a length denoted T b The value is 204.8 mus. The synchronization signal is shown as follows:
in the formula:
N b : number of subcarriers of synchronization signal
X b (i) The method comprises the following steps Carrying a binary pseudo-random sequence PN b (k) BPSK (binary phase shift keying) modulated signal of
(Δf) b : the subcarrier spacing of the synchronization signal is 4.8828125Khz.
Number of subcarriers N of synchronization signal b According to different physical layer bandwidth (B) f ) The values are as follows:
carrying binary sequence pseudorandom PN b (k) BPSK modulation signal X of b (i) From PN b (k) The mapping is generated in the following way:
B f ＝8Mhz：
B f ＝2Mhz：
referring to FIG. 2, it is a schematic diagram of a linear feedback shift register in GY/T220.1-2006 standard. The binary pseudo-random sequence is generated by a linear feedback shift register as shown in fig. 2, the generator polynomial being: x is the number of 11 +x 9 +1, the shift register initial value is the same for each synchronization signal, 01110101101.
Note that 11 shift registers from right to left in fig. 2 are registers 21, 22. The data to the right of each register is the input data to that register, the data to the left is the output data from that register, and the output data is equal to the register value. The output data of the register 211 is the output data of the register group. The values of all registers are set to corresponding initial values according to the provided initial value sequence. After setting an initial value, performing modulo-2 addition on output values of the register 211 and the register 29 to obtain a modulo-2 addition result; then, every clock of one beat comes, the value of the register 210 is given to the register 211, the value of the register 29 is given to the register 210, and so on, the value of the register 21 is given to the register 22, and the modulo-2 addition result is given to the register 21; then, the modulo-2 addition result is recalculated. Meanwhile, the output sequence of the register 211 values is a binary pseudorandom sequence.
As can be seen, the existing step of generating the synchronization signal sequence includes: firstly, generating a binary PN sequence, and then generating a time domain band-limited signal by utilizing inverse Fourier transform; wherein the PN sequence is generated by a shift register, and the generator polynomial is: x is the number of 11 +x 9 +1, the initial value of the shift register is 01110101101.
In the GY/T220.1-2006 technical standard, a system transmitting end transmits a beacon at regular time intervals, and the transmitting method comprises the following steps: firstly, generating a synchronization signal sequence of 204.8 microseconds; generating a synchronization signal sequence of 204.8 microseconds; and transmitting the two synchronous signal sequences in a cascade.
For wireless communication systems, the wireless transmission channel will have a very serious impact on the signal transmitted by the transmitter, especially the multipath fading channel. A multipath fading channel will result in a signal received by the receiver corresponding to a superposition of a plurality of attenuated transmitter transmission signals. The advantages and disadvantages of the beacon design will affect the synchronization and reception effect of the receiver.
The GY/T220.1-2006 standard has a short synchronization signal sequence used for performing cross-correlation operation, and the beacon transmission method cannot cope with a wireless channel condition with large channel time delay expansion when acquiring channel time domain impulse response. When the wireless channel is the condition of the equal-strength two-path channel and the time delay expansion of the channel is just about 204.8 microseconds, the minimum amplitude value of the self-correlation output of the receiver is large, which is not beneficial to setting the amplitude threshold value of the output result of the self-correlation operation; the threshold is used to assist in searching for the peak of the output of the autocorrelation operation to determine the location of the initial synchronization.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a beacon sending method in a mobile multimedia broadcasting system, which can cope with the wireless channel condition with larger channel delay spread when acquiring channel time domain impulse response.
In order to solve the above technical problem, the present invention provides a method for sending a beacon in a mobile multimedia broadcasting system, wherein the beacon comprises a synchronization signal sequence, and the method comprises the following steps:
(1) Generating a synchronization signal sequence;
(2) Selecting a part of continuous sequence from the last bit of the synchronous signal sequence forward, and copying the part of continuous sequence as a first cyclic prefix sequence;
(3) Obtaining a second cyclic prefix sequence according to the first cyclic prefix sequence, so that the second cyclic prefix sequence and the first cyclic prefix sequence have a determined corresponding relation;
(4) When transmitting a beacon signal, the second cyclic prefix sequence is transmitted first, the first cyclic prefix sequence is transmitted again, and the synchronization signal sequence is transmitted last.
Further, the second cyclic prefix sequence has a certain correspondence relationship, including a conjugate, with the first cyclic prefix sequence in step (3).
Further, the first cyclic prefix sequence and the second cyclic prefix sequence are equal in length.
Further, the lengths of the first cyclic prefix sequence and the second cyclic prefix sequence are both less than or equal to the length of the synchronization signal sequence.
Further, the length of the synchronization signal sequence in step (1) is 409.6 microseconds, the length of the first cyclic prefix sequence in step (2) is 102.4 microseconds, and the length of the second cyclic prefix sequence is 102.4 microseconds.
Further, the step of generating the synchronization signal sequence in step (1) includes: firstly, generating a binary PN sequence, and then generating a time domain band-limited signal by utilizing inverse Fourier transform; wherein, the PN sequence is generated by a shift register, and the generator polynomial is: x is a radical of a fluorine atom 12 +x 6 +x 4 +x 1 +1, the initial value of the shift register is 101110101101.
The beacon sending method of the invention improves the accuracy of initial synchronization, improves the searching range of channel time domain impulse response, and can deal with the wireless channel condition with larger channel time delay expansion when the channel time domain impulse response is obtained.
Drawings
FIG. 1 is a schematic diagram of an application of a conventional beacon structure in GY/T220.1-2006 standard.
FIG. 2 is a diagram of a linear feedback shift register in GY/T220.1-2006 standard.
Fig. 3 is a schematic diagram of a beacon structure according to the present invention.
FIG. 4 is a schematic diagram of a linear feedback shift register according to the present invention.
Fig. 5 is a flowchart of a beacon transmission method according to the present invention.
Detailed Description
The invention improves the accuracy of initial synchronization and improves the searching range of channel time domain impulse response by changing the structure of the synchronization signal in the beacon and the sending method thereof, and can deal with the condition of a wireless channel with larger channel time delay expansion when the channel time domain impulse response is obtained.
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Referring to fig. 3, a schematic diagram of a beacon structure according to the present invention is shown. Wherein, the length of the synchronous signal sequence is 409.6 microseconds; copying the last 102.4 microsecond-long partial sequence of the synchronization signal sequence to the front of the synchronization signal sequence, and recording the partial sequence as CP; then, the conjugate sequence of the CP sequence is placed in front of the CP, and is marked as CP * (ii) a This constitutes the synchronization signal sequence in the beacon.
The synchronization signal sequence generation process is as follows:
synchronization signal S b (t) is band limited pseudo-randomMachine signal, length is denoted as T b The value is 409.6 mus. The synchronization signal is shown in the following formula:
in the formula:
N b : number of subcarriers of synchronization signal
X b (i) The method comprises the following steps Carrying a binary pseudo-random sequence PN b (k) BPSK modulated signal of
(Δf) b : the subcarrier spacing of the synchronization signal takes the value of 2.44140625Khz.
Number of subcarriers N of synchronization signal b According to different physical layer bandwidth (B) f ) The values are as follows:
carrying binary sequence pseudo-random PN b (k) BPSK modulation signal X of b (i) From PN b The mapping is generated in the following way:
B f ＝8Mhz：
B f ＝2Mhz：
referring to fig. 4, a schematic diagram of a linear feedback shift register according to the present invention is shown. Binary pseudorandom sequence PN b (k) Generated by the linear feedback shift register shown in fig. 4, the generator polynomial is: x is a radical of a fluorine atom 12 +x 6 +x 4 +x 1 +1. The shift register initial value is the same for each synchronization signal, 101110101101.
Note that 12 shift registers from right to left in fig. 4 are registers 41, 42. The data on the right of each register is the input data of the register, the data on the left is the output data of the register, and the output data is equal to the register value. The output data of register 412 is the output data of the register set. The values of all registers are set to corresponding initial values according to the provided initial value sequence. After setting the initial value, performing modulo-2 addition on the output values of the registers 412, 46, 44 and the register 41 to obtain a modulo-2 addition result; then, every clock of one beat comes, the value of the register 411 is assigned to the register 412, the value of the register 410 is assigned to the register 411, and so on, the value of the register 41 is assigned to the register 42, and the modulo-2 addition result is assigned to the register 41; the modulo-2 addition result is then recalculated. Meanwhile, the sequence of the output register 412 values is a binary pseudorandom sequence.
Referring to fig. 5, a flowchart of a beacon transmission method according to the present invention is shown. The method for transmitting the beacon shown in fig. 2 includes the following steps:
step 501: generating a synchronization signal sequence;
the step of generating the synchronization signal sequence includes: firstly, generating a binary PN sequence, and then generating a time domain band-limited signal by utilizing inverse Fourier transform; wherein, the PN sequence is generated by a shift register, and the generator polynomial is: x is the number of 12 +x 6 +x 4 +x 1 +1, the initial value of the shift register is 101110101101.
The length of the generated synchronization signal sequence is 409.6 microseconds. The first cyclic prefix sequence is 102.4 microseconds in length. The second cyclic prefix sequence is 102.4 microseconds in length.
Step 502: selecting a part of continuous sequences from the last bit of the synchronous signal sequence forward, and copying the part of sequences as a first cyclic prefix sequence;
step 503: obtaining a second cyclic prefix sequence according to the first cyclic prefix sequence, and enabling the second cyclic prefix sequence to have a determined corresponding relation with the first cyclic prefix sequence;
the determined correspondence includes a conjugate.
Step 504: when transmitting a beacon signal, the second cyclic prefix sequence is transmitted first, the first cyclic prefix sequence is transmitted again, and the synchronization signal sequence is transmitted last.
The first cyclic prefix sequence and the second cyclic prefix sequence are equal in length. The length of the first cyclic prefix sequence and the length of the second cyclic prefix sequence are less than or equal to the length of the synchronization signal sequence.
The invention can deal with the wireless channel condition with larger channel time delay expansion when acquiring the channel time domain impulse response by changing the structure of the synchronous signal in the beacon and the sending method thereof.
Of course, the above-mentioned embodiments are not intended to limit the technical solutions of the present invention, and any equivalent replacement or corresponding modification of the technical features of the present invention by those skilled in the art still remains in the scope of the present invention.
Claims (7)
1. A method for transmitting a beacon in a mobile multimedia broadcasting system, the beacon including a synchronization signal sequence, the method comprising:
(1) Generating a synchronization signal sequence;
(2) Selecting a part of continuous sequence from the last bit of the synchronous signal sequence forward, and copying the part of continuous sequence as a first cyclic prefix sequence;
(3) Obtaining a second cyclic prefix sequence according to the first cyclic prefix sequence, so that the second cyclic prefix sequence and the first cyclic prefix sequence have a determined corresponding relation;
(4) When transmitting a beacon signal, the second cyclic prefix sequence is transmitted first, the first cyclic prefix sequence is transmitted, and the synchronization signal sequence is transmitted last.
2. The method of claim 1, wherein the determined correspondence, in step (3), that the second cyclic prefix sequence has with the first cyclic prefix sequence comprises a conjugate.
3. The method of claim 2, wherein the first cyclic prefix sequence and the second cyclic prefix sequence are equal in length.
4. The method of claim 1, 2 or 3, wherein the first cyclic prefix sequence and the second cyclic prefix sequence each have a length that is less than or equal to a length of the synchronization signal sequence.
5. The method of claim 1, wherein the synchronization signal sequence in step (1) has a length of 409.6 microseconds, the first cyclic prefix sequence in step (2) has a length of 102.4 microseconds, and the second cyclic prefix sequence has a length of 102.4 microseconds.
6. The method of any one of claims 1, 2, 3 or 5, wherein the step of generating the synchronization signal sequence in step (1) comprises: firstly, generating a binary PN sequence, and then generating a time domain band-limited signal by utilizing inverse Fourier transform; wherein, the PN sequence is generated by a shift register, and the generating polynomial is: x is the number of 12 +x 6 +x 4 +x 1 +1, the initial value of the shift register is 101110101101.
7. The method of claim 4, wherein the step of generating the synchronization signal sequence in step (1) comprises: firstly, generating a binary PN sequence, and then generating a time domain band-limited signal by utilizing inverse Fourier transform; wherein, the PN sequence is generated by a shift register, and the generator polynomial is: x is the number of 12 +x 6 +x 4 +x 1 +1, the initial value of the shift register is 101110101101.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102957651A (en) * | 2011-08-17 | 2013-03-06 | 北京泰美世纪科技有限公司 | Method and device for synchronization and receiving of digital audio broadcasting signal frequency |
| WO2014023214A1 (en) * | 2012-08-08 | 2014-02-13 | 北京泰美世纪科技有限公司 | Method and device for generating beacon signal in communication system |
| CN109417422A (en) * | 2016-07-15 | 2019-03-01 | 株式会社Kt | Method and apparatus of the transmission/reception for the synchronization signal and system information of terminal in new Radio Access Network |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100563123C (en) * | 2006-11-15 | 2009-11-25 | 北京创毅视通科技有限公司 | A kind of method that realizes sender unit identification |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102957651A (en) * | 2011-08-17 | 2013-03-06 | 北京泰美世纪科技有限公司 | Method and device for synchronization and receiving of digital audio broadcasting signal frequency |
| CN102957651B (en) * | 2011-08-17 | 2017-03-15 | 北京泰美世纪科技有限公司 | A kind of digital audio broadcasting signal Frequency Synchronization and method of reseptance and its device |
| WO2014023214A1 (en) * | 2012-08-08 | 2014-02-13 | 北京泰美世纪科技有限公司 | Method and device for generating beacon signal in communication system |
| CN103595677A (en) * | 2012-08-08 | 2014-02-19 | 北京泰美世纪科技有限公司 | A method and an apparatus for beacon signal generation in a communication system |
| CN103595677B (en) * | 2012-08-08 | 2016-11-16 | 北京泰美世纪科技有限公司 | The generation method and device of beacon signal in communication system |
| CN109417422A (en) * | 2016-07-15 | 2019-03-01 | 株式会社Kt | Method and apparatus of the transmission/reception for the synchronization signal and system information of terminal in new Radio Access Network |
| CN109417422B (en) * | 2016-07-15 | 2022-02-18 | 株式会社Kt | Method for transmitting and receiving synchronization signal and system information in new wireless access network |
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