CN103441830A - Timing synchronization method based on sounding reference signal - Google Patents
Timing synchronization method based on sounding reference signal Download PDFInfo
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Abstract
The invention relates to the technology of timing synchronization estimation, in particular to a timing synchronization method based on a sounding reference signal. The timing synchronization method based on the sounding reference signal can effectively eliminate the influence of a side lobe peak of a metric function, and improve the timing synchronization performance of an LTE uplink under a multipath fading channel. The timing synchronization method based on the sounding reference signal specifically comprises the steps that observation data and a local pilot signal make slippage correlation on a time domain, relative functions are normalized through the signal energy of the local pilot signal so that a timing metric function can be obtained, a maximum peak sampling point of the timing metric function is searched for, and a correct timing point is obtained.
Description
Technical field
The present invention relates to the Timing Synchronization estimation technique, particularly 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 subject to extensive concern at present.At down link, the LTE system adopts OFDM (Orthogonal Frequency Division Multiple Access, OFDMA) as its multi-access mode.In up link, what the LTE system adopted is the mode of single-carrier frequency division multiple access (Single-Carrier Frequency Division Multiple Access, SC-FDMA).
At the LTE up direction, there is a kind of important uplink reference signals to be called detection reference signal (Sounding Reference Signal, SRS), this signal is generated by Zadoff-Chu (ZC) sequence or QPSK sequence, with upstream data time division multiplexing, not frequency division multiplexing in a time slot.SRS, owing to having permanent envelope zero auto-correlation (Constant Amplitude Zero Auto Correlation, CAZAC) character, often is used to the operations such as quality detection, power control and Timing Synchronization of up channel.
A subscriber equipment (UE) only has after its uplink time synchronized, just can be scheduled and be transmitted data, and therefore, " timing controlled " is very important for multiple access access scheme in up community.Usually, first be synchronously with Random Access Channel (Physical Random Access Channel, PRACH) complete.After obtaining Timing Synchronization first, system can constantly be measured useful upward signal, and the time that arrives eNode B to upgrade upward signal changes, and therefore, needs detection reference signal to carry out the Timing Synchronization estimation.
And mostly the timing estimation method proposed at present is to utilize the correlation of the leading symbol of OFDM to do Timing Synchronization, or the method based on Cyclic Prefix etc.Certain methods can obtain timing and frequency deviation estimated performance preferably under awgn channel, but, under the multidiameter fading channel condition, performance there will be obvious decline.And the frequency-domain structure characteristics due to SRS, make some timing estimation methods under ofdm system and be not suitable for the SRS signal, for example, because SRS itself has a large amount of zero-frequency points, make the timing metric function in the slip related algorithm have side lobe peak, bring impact to regularly search.
Summary of the invention
The object of the present invention is to provide a kind of time synchronization method based on detection reference signal, the method can be eliminated the impact of side lobe peak in metric function effectively, has improved the Timing Synchronization performance of LTE up link under the multidiameter fading channel.
The objective of the invention is to be achieved through the following technical solutions:
S1, observation data r (n) and local pilot signal c (n) do and slide relevantly on time domain, obtain correlation function
wherein, observation data r (n) is N+2N near length detection reference signal in the SC-FDMA signal stream received
gdata, d for the search increment, the scope of d is-N
g: N
g, c
*(n) be the complex conjugate of local pilot signal, N is the number of sub carrier wave in the SC-FDMA signal, N
gfor circulating prefix-length;
S2, calculate the signal energy of local pilot signal
with R (d) normalization S1 gained correlation function P (d), obtain the timing metric function
The peak-peak MAX of S3, searching S2 gained metric function M (d), and to peak-peak, corresponding sampled point carries out mark, is designated as d
mAX, that is, and d
mAXthat corresponding footpath has the strongest instantaneous power;
S4, from d
mAXrecall L sampled point as the search window, definition thresholding β=λ * mean (M (d)) finds out leftmost three sampled points of metric function M (d)>thresholding β in the search window, and selects a middle correct timing point of conduct, wherein, and N
g/ 2≤L≤N
g, N
gbe the length of a Cyclic Prefix, λ, for adjusting coefficient, is empirical value.
Further, the described observation data r of S1 (n) at least comprises a complete detection reference signal.
Further, half of the length of a Cyclic Prefix of the described L=of S4.
Further, the described λ of S4=2.
The invention has the beneficial effects as follows: do not need to utilize Cyclic Prefix, eliminated " plateau effect " in the conventional method, by Cyclic Prefix, introduced, it is not the situation in the first footpath that the sweep backward technology has been avoided the strongest instantaneous power in the multipath channel, in three alternative timing points that search in the search window, a sampled point in the middle of getting is as correct timing point, eliminate the impact of the side lobe peak caused due to the IFFT energy leakage, improved the correct timing probability of SRS signal.
The accompanying drawing explanation
The flow chart of the timing estimation that Fig. 1 is the detection reference signal that proposes of the present invention.
The schematic diagram that Fig. 2 is the searching method that proposes of the present invention.
The mean square error simulation result figure that Fig. 3 is the SRS timing estimation.
Fig. 4 is the correct regularly probabilistic simulation of SRS figure as a result.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described:
Concrete steps of the present invention are as described in Figure 1:
S1, observation data r (n) and local pilot signal c (n) do and slide relevantly on time domain, obtain correlation function
wherein, observation data r (n) is N+2N near length detection reference signal in the SC-FDMA signal stream received
gdata, d for the search increment, the scope of d is-N
g: N
g, c
*(n) be the complex conjugate of local pilot signal, N is the number of sub carrier wave in the SC-FDMA signal, N
gfor circulating prefix-length;
S2, calculate the signal energy of local pilot signal
with R (d) normalization S1 gained correlation function P (d), obtain the timing metric function
The peak-peak MAX of S3, searching S2 gained metric function M (d), and to peak-peak, corresponding sampled point carries out mark, is designated as d
mAX, that is, and d
mAXthat corresponding footpath has the strongest instantaneous power;
S4, from d
mAXrecall L sampled point as the search window, definition thresholding β=λ * mean (M (d)) finds out leftmost three sampled points of metric function M (d)>thresholding β in the search window, and selects a middle correct timing point of conduct, wherein, and N
g/ 2≤L≤N
g/ 2, N
gfor circulating prefix-length, λ, for adjusting coefficient, is empirical value.
Below in conjunction with accompanying drawing, 2 couples of S4 make an explanation:
A, from d
mAXrecall L sampled point as search window, L=N
g/ 2;
B, described thresholding β=λ * mean (M (d)), wherein mean (M (d)) represents the mean value of timing metric function M (d), λ is for adjusting coefficient, adjusting coefficient lambda can not establish to such an extent that too littlely can not establish too greatly, if establish too greatly, can't search correct footpath; If establish too littlely, the probability of false synchronization can increase.And meet signal to noise ratio when lower, adjust coefficient larger, the pollution with noise reduction to useful signal.In order to search correct footpath, and noise reduction is to the pollution of useful signal, and threshold value is made as 2 times of left and right of metric function average usually, and the present invention gets λ=2.
The present invention has passed through simulating, verifying on the matlab emulation platform, and as shown in Figure 3 and Figure 4, simulation result shows simulation result: the method is simply effective, is applicable to the Timing Synchronization of detection reference signal in LTE, in the multipath channel environment, can realize accurately regularly.
Claims (4)
1. the time synchronization method based on detection reference signal, it is characterized in that: its step is as described below:
S1, observation data r (n) and local pilot signal c (n) do and slide relevantly on time domain, obtain correlation function
wherein, observation data r (n) is N+2N near length detection reference signal in the SC-FDMA signal stream received
gdata, d for the search increment, the scope of d is-N
g: N
g, c
*(n) be the complex conjugate of local pilot signal, N is the number of sub carrier wave in the SC-FDMA signal, N
gfor circulating prefix-length;
S2, calculate the signal energy of local pilot signal
with R (d) normalization S1 gained correlation function P (d), obtain the timing metric function
The peak-peak MAX of S3, searching S2 gained metric function M (d), and to peak-peak, corresponding sampled point carries out mark, is designated as d
mAX, that is, and d
mAXthat corresponding footpath has the strongest instantaneous power;
S4, from d
mAXrecall L sampled point as the search window, definition thresholding β=λ * mean (M (d)) finds out leftmost three sampled points of metric function M (d)>thresholding β in the search window, and selects a middle correct timing point of conduct, wherein, and N
g/ 2≤L≤N
g, N
gbe the length of a Cyclic Prefix, λ, for adjusting coefficient, is empirical value.
2. a kind of time synchronization method based on detection reference signal according to claim 1, it is characterized in that: the described observation data r of S1 (n) at least comprises a complete detection reference signal.
3. a kind of time synchronization method based on detection reference signal according to claim 1, is characterized in that: half of the length of a Cyclic Prefix of the described L=of S4.
4. a kind of time synchronization method based on detection reference signal according to claim 1, is characterized in that: the described λ of S4=2.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103873225A (en) * | 2014-03-26 | 2014-06-18 | 清华大学 | Timing estimation method for burst communication |
| CN104684071A (en) * | 2015-03-05 | 2015-06-03 | 西安电子科技大学 | LTE uplink timing synchronization tracking method |
| CN106416167A (en) * | 2016-04-20 | 2017-02-15 | 香港应用科技研究院有限公司 | Timing offset estimation by SINR measurement in OFDM-based systems |
| CN110249542A (en) * | 2016-12-05 | 2019-09-17 | 北欧半导体公司 | Digital radio |
| US11233613B2 (en) | 2016-09-12 | 2022-01-25 | Guangdong Oppo Mobile Telecommunications Corp., Ltd. | Pilot signal transmission method and device |
| CN115942446A (en) * | 2021-08-04 | 2023-04-07 | 大唐移动通信设备有限公司 | Information transmission method, device, terminal and base station |
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| CN101374131A (en) * | 2007-08-20 | 2009-02-25 | 株式会社Ntt都科摩 | Timing synchronization method and device, preamble symbol and its generation method and device |
| 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 | A Low Complexity and High Performance OFDM Timing Synchronization Algorithm |
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| CN101374131A (en) * | 2007-08-20 | 2009-02-25 | 株式会社Ntt都科摩 | Timing synchronization method and device, preamble symbol and its generation method and device |
| 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 | A Low Complexity and High Performance OFDM Timing Synchronization Algorithm |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103873225A (en) * | 2014-03-26 | 2014-06-18 | 清华大学 | Timing estimation method for burst communication |
| CN103873225B (en) * | 2014-03-26 | 2015-10-28 | 清华大学 | The timing estimation method of burst communication |
| CN104684071A (en) * | 2015-03-05 | 2015-06-03 | 西安电子科技大学 | LTE uplink timing synchronization tracking method |
| CN104684071B (en) * | 2015-03-05 | 2018-03-06 | 西安电子科技大学 | The up Timing Synchronization trackings of LTE |
| CN106416167A (en) * | 2016-04-20 | 2017-02-15 | 香港应用科技研究院有限公司 | Timing offset estimation by SINR measurement in OFDM-based systems |
| CN106416167B (en) * | 2016-04-20 | 2019-03-26 | 香港应用科技研究院有限公司 | Timing offset estimation by SINR measurement in OFDM-based systems |
| US11233613B2 (en) | 2016-09-12 | 2022-01-25 | Guangdong Oppo Mobile Telecommunications Corp., Ltd. | Pilot signal transmission method and device |
| CN110249542A (en) * | 2016-12-05 | 2019-09-17 | 北欧半导体公司 | Digital radio |
| US11070246B2 (en) | 2016-12-05 | 2021-07-20 | Nordic Semiconductor Asa | Digital radio communication |
| CN110249542B (en) * | 2016-12-05 | 2021-07-27 | 北欧半导体公司 | Digital radio communication |
| CN115942446A (en) * | 2021-08-04 | 2023-04-07 | 大唐移动通信设备有限公司 | Information transmission method, device, terminal and base station |
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