CN103441830B - A kind of time synchronization method based on detection reference signal - Google Patents
A kind of time synchronization method based on detection reference signal Download PDFInfo
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- CN103441830B CN103441830B CN201310381793.1A CN201310381793A CN103441830B CN 103441830 B CN103441830 B CN 103441830B CN 201310381793 A CN201310381793 A CN 201310381793A CN 103441830 B CN103441830 B CN 103441830B
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Abstract
The present invention relates to Timing Synchronization estimation technique, particularly to the timing estimation method of detection reference signal, the method can eliminate the impact of side lobe peak in metric function effectively, improves the Timing Synchronization performance of LTE up-link under multidiameter fading channel.Specifically including observation data, to do slip in time domain with local pilot signal relevant, obtains timing metric function, the peak-peak sampled point of searching timing metric function with the signal energy pair correlation function normalization of this locality pilot signal, obtains correct timing point.
Description
Technical field
The present invention relates to Timing Synchronization estimation technique, particularly to the timing estimation method of detection reference signal.
Background technology
LTE (Long Term Evolution), as the developing direction of next-generation mobile communications, has been now subjected to extensive concern.Under
Line link, LTE system uses OFDM (Orthogonal Frequency Division Multiple Access, OFDMA)
As its multi-access mode.In up-link, that LTE system uses is then single-carrier frequency division multiple access (Single-Carrier Frequency
Division Multiple Access, SC-FDMA) mode.
A kind of important uplink reference signals is had to be referred to as detection reference signal (Sounding Reference at LTE up direction
Signal, SRS), this signal is generated, during with upstream data in a time slot by Zadoff-Chu (ZC) sequence or QPSK sequence
Divide multiplexing, not frequency division multiplexing.SRS due to have permanent envelope zero auto-correlation (Constant Amplitude Zero Auto Correlation,
CAZAC) character, is commonly used for the operations such as the quality detection of up channel, power control and Timing Synchronization.
One subscriber equipment (UE), only after its uplink transmission time synchronizes, just can be scheduled and be transmitted data, therefore,
" timing controlled " is particularly important for multiple access schemes in up community.Generally, synchronization first is to believe with Stochastic accessing
(Physical Random Access Channel, PRACH) completes in road.After obtaining Timing Synchronization first, system can not
Measure useful upward signal, to update the time change of upward signal arrival eNode B, accordingly, it would be desirable to detection is with reference to letter disconnectedly
Number it is timed synchronization to estimate.
And the timing estimation method proposed at present mostly be the dependency utilizing the leading symbol of OFDM to do Timing Synchronization, or
Method based on Cyclic Prefix etc..Certain methods can obtain preferably timing under awgn channel and frequency deviation estimates performance, but
Being under tipath fading channel conditions, performance there will be significantly decline.And due to the frequency-domain structure feature of SRS so that some
Timing estimation method under ofdm system is not particularly suited for SRS signal, such as, have substantial amounts of zero-frequency point due to SRS itself,
Make the timing metric function in slip related algorithm there is side lobe peak, affect to timing searching strip.
Summary of the invention
It is an object of the invention to provide a kind of time synchronization method based on detection reference signal, the method can eliminate effectively
The impact of side lobe peak in metric function, improves the Timing Synchronization performance of LTE up-link under multidiameter fading channel.
It is an object of the invention to be achieved through the following technical solutions:
S1, observation data r (n) are done in time domain with local pilot signal c (n) and are slided relevant, obtain correlation functionWherein, observation data r (n) is detection reference signal in the SC-FDMA signal stream received
Neighbouring a length of N+2NgData, d for search increment, d is in the range of-Ng:Ng, c*N () is local pilot signal
Complex conjugate, N is the number of sub carrier wave in SC-FDMA signal, NgFor circulating prefix-length；
S2, the signal energy of the local pilot signal of calculatingWith R (d) normalization S1 gained correlation function
P (d), obtains timing metric function
S3, peak-peak MAX of searching S2 gained metric function M (d), and the sampled point that peak-peak is corresponding is marked
Note, is designated as dMAX, i.e. dMAXThat corresponding footpath has the strongest instantaneous power；
S4, from dMAXRecall L sampled point as search window, define thresholding β=λ * mean (M (d)), in search window
Find out leftmost three sampled points of metric function M (d) ＞ thresholding β, and select one of centre as correct timing point,
Wherein, Ng/2≤L≤Ng, NgBeing the length of a Cyclic Prefix, λ is regulation coefficient, for empirical value.
Further, data r (n) are observed described in S1 including at least a complete detection reference signal.
Further, the half of the length of mono-Cyclic Prefix of L=described in S4.
Further, λ=2 described in S4.
The invention has the beneficial effects as follows: need not utilize Cyclic Prefix, eliminate in traditional method and " put down by what Cyclic Prefix introduced
Top effect ", it is not the situation in the first footpath that sweep backward technology avoids the strongest instantaneous power in multipath channel, searches in search window
Rope to three alternative timing points in, take centre a sampled point as correct timing point, eliminate due to IFFT energy
Reveal the impact of the side lobe peak caused, improve the correct timing probability of SRS signal.
Accompanying drawing explanation
Fig. 1 is the flow chart of the timing estimation of the detection reference signal that the present invention proposes.
Fig. 2 is the schematic diagram of the searching method that the present invention proposes.
Fig. 3 is the mean square error simulation result figure of SRS timing estimation.
Fig. 4 is SRS correct timing probabilistic simulation result figure.
Detailed description of the invention
The detailed description of the invention of the present invention is described below in conjunction with the accompanying drawings:
The concrete steps of the present invention are as described in Figure 1:
S1, observation data r (n) are done in time domain with local pilot signal c (n) and are slided relevant, obtain correlation functionWherein, observation data r (n) is detection reference signal in the SC-FDMA signal stream received
Neighbouring a length of N+2NgData, d for search increment, d is in the range of-Ng:Ng, c*N () is local pilot signal
Complex conjugate, N is the number of sub carrier wave in SC-FDMA signal, NgFor circulating prefix-length；
S2, the signal energy of the local pilot signal of calculatingWith R (d) normalization S1 gained correlation function
P (d), obtains timing metric function
S3, peak-peak MAX of searching S2 gained metric function M (d), and the sampled point that peak-peak is corresponding is marked
Note, is designated as dMAX, i.e. dMAXThat corresponding footpath has the strongest instantaneous power；
S4, from dMAXRecall L sampled point as search window, define thresholding β=λ * mean (M (d)), in search window
Find out leftmost three sampled points of metric function M (d) ＞ thresholding β, and select one of centre as correct timing point,
Wherein, Ng/2≤L≤Ng/ 2, NgFor circulating prefix-length, λ is regulation coefficient, for empirical value.
2 couples of S4 explain below in conjunction with the accompanying drawings:
A, from dMAXRecall L sampled point as search window, L=Ng/2；
B, described thresholding β=λ * mean (M (d)), wherein mean (M (d)) represents the average of timing metric function M (d)
Value, λ is regulation coefficient, and regulation coefficient λ can not be made too small and can not set the biggest, if setting the biggest, then cannot search
Rope is to correct footpath；If be made too small, then the probability of false synchronization can increase.And meet signal to noise ratio the lowest time, regulation coefficient is more
Greatly, to reduce the noise pollution to useful signal.In order to be able to search correct footpath, and reduce noise to useful signal
Polluting, threshold value is typically set to about 2 times of metric function average, and the present invention takes λ=2.
The present invention have passed through simulating, verifying on matlab emulation platform, simulation result as shown in Figure 3 and Figure 4, simulation result
Show: the method is the most effective, it is adaptable to the Timing Synchronization of detection reference signal in LTE, can be real in multi-path channel environment
Timing the most accurately.
Claims (4)
1. a time synchronization method based on detection reference signal, it is characterised in that: its step is as described below:
S1, observation data r (n) are done in time domain with local pilot signal c (n) and are slided relevant, obtain correlation functionWherein, observation data r (n) is detection reference signal in the SC-FDMA signal stream received
Neighbouring a length of N+2NgData, d for search increment, d is in the range of-Ng:Ng, c*N () is local pilot signal
Complex conjugate, N is the number of sub carrier wave in SC-FDMA signal, NgFor circulating prefix-length；
S2, the signal energy of the local pilot signal of calculatingWith R (d) normalization S1 gained correlation function
P (d), obtains timing metric function
S3, peak-peak MAX of searching S2 gained metric function M (d), and the sampled point that peak-peak is corresponding is marked,
It is designated as dMAX, i.e. dMAXThat corresponding footpath has the strongest instantaneous power；
S4, from dMAXRecall L sampled point as search window, define thresholding β=λ * mean (M (d)), look in search window
Go out leftmost three sampled points of metric function M (d) ＞ thresholding β, and select one of centre as correct timing point, its
In, Ng/2≤L≤Ng, NgBeing the length of a Cyclic Prefix, λ is regulation coefficient, for empirical value.
A kind of time synchronization method based on detection reference signal, it is characterised in that: described in S1
Observation data r (n) is including at least a complete detection reference signal.
A kind of time synchronization method based on detection reference signal, it is characterised in that: described in S4
The half of the length of mono-Cyclic Prefix of L=.
A kind of time synchronization method based on detection reference signal, it is characterised in that: described in S4
λ=2.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103873225B (en) * | 2014-03-26 | 2015-10-28 | 清华大学 | The timing estimation method of burst communication |
| CN104684071B (en) * | 2015-03-05 | 2018-03-06 | 西安电子科技大学 | The up Timing Synchronization trackings of LTE |
| WO2017181352A1 (en) * | 2016-04-20 | 2017-10-26 | Hong Kong Applied Science and Technology Research Institute Company Limited | Timing offset estimation in an ofdm-based system by sinr measurement |
| BR112019003806B8 (en) | 2016-09-12 | 2024-01-30 | Guangdong Oppo Mobile Telecommunications Corp Ltd | Method of transmitting a channel state information reference signal, and communication device |
| GB201620669D0 (en) | 2016-12-05 | 2017-01-18 | Nordic Semiconductor Asa | Digital radio communication |
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|---|---|---|---|---|
| CN101374131A (en) * | 2007-08-20 | 2009-02-25 | 株式会社Ntt都科摩 | Method and apparatus of timing synchronization, leading symbol as well as method and apparatus for generating the same |
| CN102340864A (en) * | 2011-10-08 | 2012-02-01 | 中国科学院上海微系统与信息技术研究所 | OFDM (Orthogonal Frequency Division Multiplexing) timing synchronization algorithm with low complexity and high performance |
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|---|---|---|---|---|
| CN101374131A (en) * | 2007-08-20 | 2009-02-25 | 株式会社Ntt都科摩 | Method and apparatus of timing synchronization, leading symbol as well as method and apparatus for generating the same |
| CN102340864A (en) * | 2011-10-08 | 2012-02-01 | 中国科学院上海微系统与信息技术研究所 | OFDM (Orthogonal Frequency Division Multiplexing) timing synchronization algorithm with low complexity and high performance |
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| A novel time and frequency synchronization scheme for OFDM systems;Guo Yi，Liu Gang，Ge Jianhua;《IEEE Transactions on Consumer Eletronics》;IEEE;20080715;第54卷(第2期);全文 * |
| OFDM系统中符号定时同步技术研究;许斌、段波、孙维新;《装备指挥技术学院学报》;20110428;第22卷(第2期);全文 * |
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