CN102694762B - Method for realizing synchronization of carrier and sampling clock, and user site device - Google Patents
Method for realizing synchronization of carrier and sampling clock, and user site device Download PDFInfo
- Publication number
- CN102694762B CN102694762B CN201110237054.6A CN201110237054A CN102694762B CN 102694762 B CN102694762 B CN 102694762B CN 201110237054 A CN201110237054 A CN 201110237054A CN 102694762 B CN102694762 B CN 102694762B
- Authority
- CN
- China
- Prior art keywords
- sampling
- data
- sample
- sent
- frequency deviation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000005070 sampling Methods 0.000 title claims abstract description 122
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000012549 training Methods 0.000 claims description 40
- 230000001360 synchronised effect Effects 0.000 claims description 25
- 238000011144 upstream manufacturing Methods 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 13
- 238000012545 processing Methods 0.000 claims description 10
- 238000001914 filtration Methods 0.000 claims description 8
- 125000004122 cyclic group Chemical group 0.000 claims description 4
- 239000013256 coordination polymer Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims description 3
- 239000002243 precursor Substances 0.000 abstract 1
- 238000004891 communication Methods 0.000 description 13
- 230000005540 biological transmission Effects 0.000 description 6
- 230000007246 mechanism Effects 0.000 description 6
- 238000013461 design Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 3
- 230000007774 longterm Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000000819 phase cycle Methods 0.000 description 2
- 101100172132 Mus musculus Eif3a gene Proteins 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Landscapes
- Synchronisation In Digital Transmission Systems (AREA)
Abstract
The invention discloses a method for realizing synchronization of a carrier and a sampling clock. The method comprises the steps of: determining a carrier frequency deviation and a sampling clock frequency deviation according to the received downlink signal; carrying out carrier frequency compensation according to uplink to-be-sent data; and carrying out sampling clock frequency compensation according to the uplink to-be-sent data. The invention also provides a user site device, which comprises a carrier frequency deviation measuring unit, a frequency deviation compensating unit, a sampling clock frequency deviation measuring unit and a clock sampling frequency compensating unit. According to the invention, the problem of synchronization of medium-short distance messaging systems based on control is solved, especially, the problem of synchronization when uplink multiple users are accessed in parallel is solved. The synchronization of the time and the frequency is mainly completed by an STA according to a downlink synchronization precursor, the deviation of the frequency and the sampling clock frequency is preprocessed, the synchronization problem is simplified to the signal-user synchronization problem, so that multiple access interference is eliminated without a complicated algorithm when a receiving end separates data of multiple users.
Description
This application claims the applying date is 2011.3.25, Application No. 201110074379.7, a kind of invention entitled realization
The priority of the synchronous earlier application of method, equipment and wireless communication system of carrier wave and sampling clock, this earlier application complete
Portion's content all embodies in this application.
Technical field
The present invention relates to wireless communication technology field, specifically, be related to realize carrier wave and the synchronous method of sampling clock,
User site equipment.
Background technology
In a communications system, be synchronously correct demodulating information basis.The synchronization of broad sense includes time synchronized, frequency together
Step, power adjustment, channel estimation etc..
In wireless local area network (WLAN) system based on IEEE802.11 standard, it is burst between access point AP and user site STA
The communication of mode, no matter being AP to STA or STA to AP direction, communicates every time（Including data transfer and control information transmission）
It is required for carrying synchronizing information, to assist to complete the synchronizing process between STA and AP.Transmit data to as a example STA by AP, STA
Receive AP synchronization preamble, time synchronized point and carrier wave frequency deviation are determined according to synchronization preamble, then could receiving data, solved
Adjust.When STA transmits data to AP, AP repeats the synchronous flow process of above-mentioned STA.
In mobile WiMAX system, it is also adopted by sending the mode of leading symbol, Long Term Evolution in down direction（LTE, Long
Term Evolution）System is then to send master sync signal（PSS, Primary Synchronization Signal）With
Auxiliary synchronous signals（SSS, Secondary Synchronization Signal）, mobile terminal is complete according to leading or synchronizing signal
Become time synchronized and Frequency Synchronization.During uplink, synchronization is completed using close-loop control mode, that is, terminal is initiated at random to base station
Access procedure, estimates, by base station, the propagation delay that the random access sequence that terminal sends is passed through, base station is estimated according to propagation delay
Count and issue timing advance instruction to terminal, terminal indicates according to timing advance in uplink and sends upstream data.
In order to improve efficiency and the availability of frequency spectrum of short-distance and medium-distance communication system, need to introduce scheduling mechanism and multiple access accesses
Mechanism, will realize this target must have suitable synchronization mechanism cooperation.It is same that leading realization is all passed through in wlan system two-way communication
The mode of step, although this method of synchronization is simple, efficiency is low and cannot meet the demand that multi-user communicates simultaneously, on the one hand no
It is required for carrying leading meeting holding time resource by packet how long；On the other hand, the access way of CSMA/CA is not inherently
Support that multi-user is concurrently accessed the synchronisation requirement being therefore unsatisfactory for when multi-user communicates simultaneously.Mobile WiMAX and LTE system same
Step mode can be used for reference, but both uplink synchronous require closed loop control, has high demands to synchronous；In addition mobile terminal and base station are adopted
Process sampling clock stationary problem, the WLAN devices of inapplicable low cost with the carrier wave crystal oscillator of higher cost.Therefore
Need synchronization mechanism reasonable in design in the short-distance and medium-distance communication system based on scheduling, when reaching carrier frequency synchronization and sampling
Clock is synchronous.
Content of the invention
In view of this, the technical problem to be solved is to provide a kind of side realizing carrier wave and sampling clock synchronization
Method and user site equipment, are synchronously required with the short-distance and medium-distance communication system meeting based on scheduling.
The present invention provides a kind of method realizing carrier wave and sampling clock synchronization, comprises the steps：
Downstream signal according to receiving determines carrier wave frequency deviationAnd sample clock frequency deviation；
According to describedCarrier frequency compensation is carried out to up data to be sent；
According to describedSample clock frequency compensation is carried out to up data to be sent.
The present invention also provides a kind of user site equipment, including：
Carrier wave frequency deviation calculates unit, obtains carrier wave frequency deviation for measuring and calculating；
Frequency offset compensation element, for according to described carrier wave frequency deviationFrequency compensation is carried out to up data to be sent；
Sampling clock frequency deviation calculates unit, for calculating sample clock frequency deviation；
Clock frequency compensating unit, for according to described sample clock frequency deviationUp data to be sent is adopted
Sample clock frequency compensates.
The present invention also provides a kind of wireless communication system realizing carrier wave and sampling clock synchronization, including：
Access point, for sending, down-going synchronous are leading, and carry out channel estimation after receiving the signal that user site is sent
And Phase Tracking, it is respectively used to eliminate phase deviation, residual frequency departure and the residual sample clock frequency deviation of sampling clock；
User site, for determining carrier wave frequency deviation according to the downstream signal receivingAnd sample clock frequency deviation；
According to describedCarrier frequency compensation is carried out to up data to be sent；According to describedUp data to be sent is adopted
Sample clock frequency compensates.
In sum, in the technical scheme that the present invention provides, according to carrier wave frequency deviation, up data to be sent is carried out accordingly
Frequency compensation；Downstream signal according to receiving determines sample clock frequency deviation, and inclined based on described sample clock frequency
Difference carries out corresponding sample clock frequency compensation to up data to be sent, to solve the short-distance and medium-distance communication system based on scheduling
Stationary problem, stationary problem when especially uplink multi-users access parallel.And can be obtained more accurate by leading design
Timing estimation, offset estimation, the precision of sampling clock estimation of deviation and scope.According to the present invention, can be located in advance by uplink frequency offset
Reason and upstream sampling clock deviation pretreatment avoid AP end to do the multi-access inference MAI Processing for removing of complexity.The synchronization that the present invention is carried
In mechanism, the main task of time and Frequency Synchronization all relies on down-going synchronous leading completing by STA, especially frequency and sampling
Frequency deviation of clock pretreatment, stationary problem is reduced to the stationary problem of single user, so that receiving terminal separates multi-user's
The algorithm not needing complexity during data eliminates multi-access inference.
Brief description
Fig. 1 is the method flow diagram realizing carrier wave and sampling clock synchronization in the embodiment of the present invention；
Carrier frequency that Fig. 2 provides for the present invention and sample clock frequency are in the compensation method principle schematic of time domain；
Fig. 3 is the carrier wave frequency deviation of offer and sampling clock frequency deviation preprocess method flow chart in the embodiment of the present invention；
The synchronization preamble structural representation adopting in Fig. 4 embodiment of the present invention；
Fig. 5 is the synchronous method flow chart providing in the embodiment of the present invention in the embodiment of the present invention；
Fig. 6 constitutes schematic diagram for a kind of user site equipment providing in the embodiment of the present invention.
Specific embodiment
One skilled in the art will appreciate that the purpose of carrier frequency synchronization is to correct due to both transmitter and receivers frequency
The discordance of agitator and the frequency shift (FS) of Doppler effect generation, the receiver based on OFDM technology carries out FFT
Frequency deviation must be estimated before and be compensated, to reduce the destruction of orthogonality between frequency deviation sub-carrier.Especially up many
During user's parallel transmission, carrier frequency synchronization is more important, because multiple transmitting website（As user site STA）Carrier center
Frequency and receiving station（Access point AP）Centre carrier frequency deviation different, the frequency deviation of each STA can affect nearby frequency bands
Cause inter-carrier interference（ICI）, general method be in receiving terminal first with multiple wave filter by Signal separator more individually to each
The impact that road signal is carried out frequency offset correction or removed frequency deviation by interference elimination method, the former equipment when number of users is more
Cost substantially increases, and the latter then can increase process and postpone.
Ideally, the sample clock frequency of receiving terminal and transmitting terminal should meet the sample rate of integral multiple, but due to crystalline substance
Shake and itself there is skew, both frequency deviation of clock are no longer the relations of integral multiple.Sampling clock is synchronously so that receiving
The sample clock frequency sending out two ends is consistent with phase place.The deviation of sampling clock phase is easily handled, and can be classified as Symbol Timing problem,
And sample clock frequency deviation（SFO,Sampling frequency offset）Carrier phase can be made to rotate, lead to subcarrier
Between interference, destroy the orthogonality between subcarrier, and can increase in time, lead to signal demodulation mistake, deteriorate system
System performance.During multi-user communication, receiving terminal also can run into the problem similar with carrier frequency synchronization：If one in time domain correlation
The sampling clock deviation of the signal of individual user site STA, how the sampling clock deviation of the signal of other STA is processed？
In view of this, the present invention provides a kind of scheme realizing carrier wave and sampling clock synchronization, uses in cell site
Point（STA）Upstream data is carried out with the method that carrier wave frequency deviation and sampling clock deviation compensate, without receiving station（AP）Do complexity
Process, that is, transmitting when anticipate, be therefore referred to as " precompensation ".
Because carrier frequency and sample clock frequency generally result from same clock source, then the precision of offset estimation and SFO
Estimated accuracy identical.For example, offset estimation error can arrive the 1% of subcarrier spacing, subcarrier spacing 78.125kHz, then relatively
Offset estimation error is
78.125*103*1%/(5.8*109) ≈ 0.135ppm,
That is, SFO estimation difference can reach 0.135ppm.Therefore estimating of SFO can be obtained by Nonlinear Transformation in Frequency Offset Estimation
Meter.
Precompensation includes two aspects：Carrier wave frequency deviation precompensation and sampling clock frequency deviation pre-compensation.First, STA is according to AP
The downlink frame sending estimates carrier wave frequency deviation.Secondly, after STA is pre-compensated for so that being compensated to frequency deviation before upstream data transmission
Transmitting terminal carrier frequency and receiving terminal carrier frequency difference in allowed band, the subcarrier spacing that such as deviation is less than 1%.
In a tdd system, the transmitting-receiving of STA uses identical carrier frequency, therefore of descending offset estimation, upstream data can be made
Precompensation.The precompensation of carrier wave frequency deviation can complete in time domain or frequency domain.Finally, STA calculates according to the downlink frame that AP sends and adopts
Sample clock frequency deviation, before upstream data sends, pre-compensates for so that launching data sample to sampling clock frequency deviation in time domain or frequency domain
The receiving terminal sampling interval is approached at equivalent sampling interval.
The method flow diagram realizing carrier wave and sampling clock synchronization that Fig. 1 provides for the present invention.With reference to Fig. 1, the present invention carries
For a kind of realize the synchronous method of carrier wave and sampling clock, comprise the steps：
S01, the downstream signal according to receiving determines carrier wave frequency deviationAnd sample clock frequency deviation；
S02, according to describedCarrier frequency compensation is carried out to up data to be sent；
S03, according to describedSample clock frequency compensation is carried out to up data to be sent.
Carrier wave frequency deviation in embodiments of the invention, in step S01Obtained according to synchronization preamble measuring and calculating, described
There is in synchronization preamble short training sequence and long training sequence, calculate described carrier wave frequency deviationStep include：
STA carries out to receipt signal postponing auto-correlation processing, carries out postponing auto-correlation processing using described short training sequence
Obtain preliminary frequency offset estimation result, carry out delay auto-correlation processing using described long training sequence and obtain accurate carrier wave frequency deviation
Estimate.
In embodiments of the invention, the downstream signal that the basis in step S01 receives determines sample clock frequency deviation, specifically include：
Relative frequency deviation is calculated according to carrier wave frequency deviation, whereinFor signal(-) carrier frequency, by this relative frequency deviationMake
Estimate for sample clock frequency deviation.
In embodiments of the invention, in step S02, according to carrier wave frequency deviationUp data to be sent is carried out accordingly
Frequency compensation；Specifically include：
According to described carrier wave frequency deviation, by following process, upstream data is compensated during user site transmission data：
Wherein, u (n) is user site upstream data time domain samples point to be sent,For theoretical baseband sample sampling
Interval.
Fig. 2 show the carrier frequency and sample clock frequency compensation method principle schematic in time domain.With reference to Fig. 2, this
In inventive embodiment, in step S02, corresponding sample clock frequency compensation is carried out to up data to be sent, specifically include：
Described up data to be sent is up-sampled by STA, and its sampling interval is,Represent the base band of STA
Specimen sample is spaced, and N is integer, represents up-sampling multiple；
WillCarry out time domain interpolation as new sampling clock deviation so that after interpolation sample equivalent sampling
It is spaced apart, wherein；
Represent the equivalent sampling interval after interpolation.After interpolation, the true samples interval of data remains, this
When, sample value equal to the sampling interval isWhen sample value；
Low-pass filtering and down-sampling are carried out to sample data (described up data to be sent) so that upper line number to be sent
Equivalent sampling according to sample is spaced apart.
It should be noted that here does not change the frequency of sampling clock using time domain interpolation method, but to transmitting-receiving two
The signal phase rotation that the sample clock frequency deviation at end causes and amplitude scaling compensate, and are equivalent to and will send end sample
Sampling interval is transformed into the sampling interval of receiving terminal that is to say, that assuming that the sampling interval of receiving terminal is, thenApproach.
With reference to Fig. 3, the carrier wave frequency deviation providing in the embodiment of the present invention and sampling clock frequency offset precompensation method, including step
As follows：
a）STA estimates carrier wave frequency deviation according to synchronization preamble；
The embodiment of the present invention provides a kind of synchronization preamble, including short training sequence（S-Preamble）And long training sequence
(L-Preamble)：Described short training sequence includes first circulation prefix CP1 and multiple period 1 sequence, described long training sequence
Row include second circulation prefix CP2 and multiple second round sequence；The length of described period 1 sequence is less than described second week
The length of phase sequence.Thus meeting the different requirements of parameter estimation, using the short cycle in short training sequence（Period 1 sequence）,
Meet larger parameter estimation range requirement, using long period in long training sequence（Second round sequence）, meet parameter estimation
Required precision.
It is preferred that the embodiment of the present invention adopts synchronization preamble as shown in Figure 4 concrete, described synchronization preamble includes two
OFDM symbol, one of OFDM symbol is short training sequence（S-Preamble）, by cyclic prefix CP 1 and 8 identical weeks
Phase sequence（S1～S8）Composition；Another OFDM symbol is long training sequence (L-Preamble), by cyclic prefix CP 2 and two
Identical periodic sequence（L1 and L2）Composition.
The short training sequence S-Preamble of synchronization preamble has 8 cycles, has been believed that 9 cycles including CP1, STA can
Obtain preliminary frequency offset estimation result so that receipt signal is done with delay auto-correlation（Coarse frequency offset）, due to the week of short training sequence
Phase is comparatively short, it is possible to obtain wider frequency offset estimation range.Long training sequence L-Preamble has 2 cycles, and STA can dock
Collect mail number do delay auto-correlation processing obtain more more accurate frequency offset estimation result than coarse frequency offset（Thin offset estimation）.
Periodic sequence is used for estimating that maximum frequency deviation estimation range during carrier wave frequency deviation is：
Wherein, D represents the sample points in a cycle,Represent the sampling interval.During bandwidth 20MHz,=50ns.S-
The cycle D=32 of Preamble, therefore maximum frequency deviation estimation range is：312.5kHz；The cycle D=128 of L-Preamble, therefore
Maximum frequency deviation estimation range is 78.125kHz.
The root-mean-square error of normalization offset estimation, L represents signal length when carrying out related calculation,
L is longer, and estimation difference is less.Therefore accurate offset estimation can be obtained with long training sequence L-Preamble.
B) STA calculates relative frequency deviation；
WhereinFor signal(-) carrier frequency.
C) obtain sample clock frequency deviation to estimate；
In the present embodiment, by relative frequency deviationEstimate as sample clock frequency deviation, that is,.
In addition, can be using other method of estimation measuring and calculating sample clock frequency deviations in the embodiment of the present invention.For example, it is presented herein below
The method of estimation of another kind of sample clock frequency deviation：
Each OFDM symbol has discrete pilot tone in frequency domain, generally can configure 4,6 or 8, even more many.This
A little pilot tones are symmetrically dispersed in direct current carrier DC both sides, and receiving terminal, can after being fast Fourier transform FFT to receipt signal
Sample value according to these pilot frequency locations and channel estimation results estimate sampling clock deviation.Because pilot number is limited,
Its estimated accuracy of pilot value only relying on a symbol is unsatisfactory, generally also makes flat of the pilot tone sample value in multiple symbols
All, but can lead to process postpone.
D) carrier synchronization pretreatment is carried out to up data to be sent；
Specifically, carrier synchronization pretreatment includes carrier wave frequency deviation precompensation.
Pretreatment can compensate to time serieses in time domain or compensate in frequency domain.
In the present embodiment, carry out carrier wave frequency deviation precompensation in time domain, specific as follows：
If the carrier frequency of AP is, the carrier frequency of STA is, do not consider channel circumstance and effect of noise, STA
The baseband sampling signal that the AP that receives sends is：
Wherein, s (n) represents the time domain data sample point of AP transmitting,Represent the preferable sampling interval,
For carrier wave frequency deviation.STA obtains carrier wave frequency deviation according to the leading estimation of down-going synchronous, as follows to upper during STA transmission data
Row data carries out carrier wave frequency deviation compensation：
Wherein, u (n) represents STA upstream data time domain samples point to be sent.
E) up data to be sent is carried out with sampling clock synchronization pretreatment.
Specifically, sampling clock synchronization pretreatment includes the precompensation of sampling clock frequency deviation.
The precompensation method carrying out sampling clock frequency deviation in time domain is as follows：
With reference to Fig. 2,In the sampling interval of expression STA, the sampling interval of AP is,,Represent STA and
Sampling clock deviation between AP, the purpose of precompensation be intended to the sampling interval isSample value be converted to the sampling interval and be's
Sample value, due to the presence of SFO estimation difference, the equivalent sampling interval of final sample can only be approached, use in Fig. 4Table
Show, now, very small sampling clock deviation can be ignored on the impact of system SNR.
STA is according to the result of offset estimationCalculate the estimation of SFO：, whereinRepresent carrier frequency.
When carrying out sample clock frequency compensation, sample data is first carried out up-sampling process, sampling interval by STA, N
For integer, represent up-sampling multiple.
Then time domain interpolation, willAs new sampling clock deviation input time domain interpolation module so that interpolation
Sample equivalent sampling is spaced apart afterwards, wherein；
Finally sample data is done with low-pass filtering and down-sampling, the equivalent sampling of the sample of final output is spaced apart.
With reference to Fig. 5, the synchronous method flow process providing in the embodiment of the present invention includes：
S511, downgoing time is synchronous；
STA detects synchronization preamble according to downlink frame, and calculates the original position of synchronization preamble.
S512, downstream frequency is synchronous；
STA is according to the down-going synchronous receiving leading estimation carrier wave frequency deviation, and the downstream signal receiving is carried out accordingly
Frequency compensation.
S513, descending sampling clock is synchronous；
STA calculates relative frequency deviation, whereinFor signal(-) carrier frequency, using this relative frequency deviation as sampling clock
Frequency offset estimation, corresponding sample clock frequency compensation is carried out to the downlink data receiving.
S514, upstream frequency pretreatment；
Carrier synchronization pretreatment is carried out to up data to be sent, using described carrier wave frequency deviationCarry out corresponding frequency
Compensate.
S515, upstream sampling clock pretreatment；
Sample clock frequency pretreatment is carried out to up data to be sent, is estimated based on described sample clock frequency deviation
Carry out corresponding sample clock frequency compensation so that adopting of receiver is approached at the equivalent sampling interval of up data sample to be sent
Sample is spaced.
S516, channel estimation and Phase Tracking.
Access point AP carries out channel estimation and Phase Tracking after receiving the signal that user site is sent, and is respectively used to eliminate
The phase deviation of sampling clock, residual frequency departure and residual sample clock frequency deviation.
With reference to Fig. 6, the embodiment of the present invention also provides a kind of user site equipment 600, including：
Carrier wave frequency deviation calculates unit 61, obtains carrier wave frequency deviation for measuring and calculating；
Frequency offset compensation element 62, for according to described carrier wave frequency deviationFrequency compensation is carried out to up data to be sent；
Sampling clock frequency deviation calculates unit 63, for calculating sample clock frequency deviation；
Clock frequency compensating unit 64, for according to described sample clock frequency deviationUp data to be sent is carried out
Sample clock frequency compensates.
It is preferred that described downstream signal includes synchronization preamble, described synchronization preamble includes short training sequence and long training sequence
Row.Described carrier wave frequency deviation calculates unit 61, for carrying out to the downstream signal receiving postponing auto-correlation processing, using described short
Training sequence obtains preliminary frequency offset estimation result, obtains accurate frequency offset estimation result using described long training sequence.
It is preferred that described short training sequence includes first circulation prefix CP1 and multiple period 1 sequence, described long training
Sequence includes second circulation prefix CP2 and multiple second round sequence；The length of described period 1 sequence is less than described second
The length of periodic sequence.
It is preferred that described short training sequence and described long training sequence respectively take an OFDM symbol.
It is preferred that described sampling clock frequency deviation calculates unit 63, according to described carrier wave frequency deviationCalculate relative frequency deviation, whereinFor the carrier frequency of described downstream signal, by this relative frequency deviationEstimate as sample clock frequency deviation.
It is preferred that described frequency offset compensation element 62, for when sending data, according toTo up
Data to be sent carries out carrier frequency compensation；Wherein, u (n) is user site upstream data time domain samples point to be sent,For
The theoretical baseband sample sampling interval.
It is preferred that described clock frequency compensating unit 64, including：
Up-sampling module 64a, described up data to be sent is up-sampled, the sampling interval is,It is use
In the baseband sample sampling interval of family website, N is up-sampling multiple, and N is integer；
Interpolating module 64b, for inciting somebody to actionCarry out time domain interpolation as new sampling clock deviation so that interpolation
Sample equivalent sampling is spaced apart afterwards, wherein；
Low-pass filtering module 64c, for carrying out low-pass filtering to the sample data after interpolation；
Down sample module 64d, for carrying out down-sampling to the data after low-pass filtered so that upstream data to be sent
The equivalent sampling of sample is spaced apart.
The user site equipment providing in the present embodiment, achievable uplink frequency offset pretreatment and upstream sampling clock deviation are located in advance
Reason, it is to avoid AP does at end the multi-access inference of complexity（MAI, Multiple Access Interference）Processing for removing, it is concrete
Operation principle and flow process, as described in preceding method, will not be described here.
The embodiment of the present invention also provides a kind of wireless communication system realizing carrier wave and sampling clock synchronization, including：
Access point, transmission down-going synchronous are leading, and carry out channel estimation and phase after receiving the signal that user site is sent
Position is followed the tracks of, and is respectively used to eliminate phase deviation, residual frequency departure and the residual sample clock frequency deviation of sampling clock；
User site, the downstream signal according to receiving determines carrier wave frequency deviationAnd sample clock frequency deviation；According to
DescribedCarrier frequency compensation is carried out to up data to be sent；According to describedWhen up data to be sent is sampled
Clock frequency compensation.
The wireless communication system providing in the present embodiment, achievable carrier wave and sampling clock are synchronous, concrete operating principle and
Flow process, as described in preceding method, will not be described here.
In sum, in the technical scheme that the present invention provides, according to carrier wave frequency deviationPhase is carried out to up data to be sent
The frequency compensation answered；Downstream signal according to receiving determines sample clock frequency deviation, and based on described sampling clock frequency
Rate deviationCorresponding sample clock frequency compensation is carried out to up data to be sent, is led to the short-distance and medium-distance solving based on scheduling
Letter system synchronization problem, stationary problem when especially uplink multi-users access parallel.And ratio can be obtained by leading design
More accurate timing estimation, offset estimation, the precision of sampling clock estimation of deviation and scope.By uplink frequency offset pretreatment and up
Sampling clock deviation pretreatment avoids AP end to do the multi-access inference MAI Processing for removing of complexity.In the synchronization mechanism that the present invention is carried, when
Between and the main task of Frequency Synchronization all rely on down-going synchronous leading completing by STA, especially frequency and sampling clock deviation are pre-
Process the stationary problem that stationary problem is reduced to single user, so that not needing complexity when receiving terminal separates the data of multi-user
Algorithm eliminate multi-access inference.
Although the present invention is open as above with preferred embodiment, it is not for limiting the present invention, any this area skill
Art personnel without departing from the spirit and scope of the present invention, can make possible variation and modification, the therefore guarantor of the present invention
Shield scope should be defined by the scope that the claims in the present invention are defined.
Claims (11)
1. a kind of synchronous method of carrier wave and sampling clock of realizing is it is characterised in that comprise the steps：
User site determines carrier wave frequency deviation according to the downstream signal that the access point AP receiving sendsInclined with sample clock frequency
Difference ζ；
According to describedCarrier frequency compensation is carried out to up data to be sent；Specifically include：According to describedSending number
According to when by following process, carrier frequency compensation is carried out to up data to be sent：
Wherein, u (n) is user site upstream data time domain samples point to be sent, TsFor the theoretical baseband sample sampling interval；
Sample clock frequency compensation is carried out to up data to be sent according to described ζ；Described up data to be sent is adopted
Sample clock frequency compensates, and specifically includes：
Described up data to be sent is up-sampled, the sampling interval isTiRepresent that the baseband sample of user site is adopted
Sample is spaced, and N is integer, represents up-sampling multiple；
WillCarry out time domain interpolation as new sampling clock deviation so that the equivalent sampling of sample is spaced apart after interpolation
Low-pass filtering and down-sampling are carried out to described up data to be sent so that described up data sample to be sent equivalent
Sampling interval is.
2. the method for claim 1 it is characterised in that：
Described downstream signal includes synchronization preamble, and described synchronization preamble includes short training sequence and long training sequence；
The downstream signal receiving is carried out postpone auto-correlation processing, obtain preliminary offset estimation using described short training sequence
As a result, obtain accurate frequency offset estimation result using described long training sequence
3. method as claimed in claim 2 it is characterised in that：
Described short training sequence includes first circulation prefix CP1 and multiple period 1 sequence, and described long training sequence includes
Two cyclic prefix CP 2 and multiple second round sequence；The length of described period 1 sequence is less than described second round sequence
Length.
4. method as claimed in claim 3 it is characterised in that：
Described short training sequence and described long training sequence respectively take an OFDM symbol.
5. according to the downstream signal receiving, the method for claim 1 is it is characterised in that determine that sample clock frequency is inclined
Difference ζ, specifically includes：
According to described carrier wave frequency deviationCalculate relative frequency deviationWherein fcFor the carrier frequency of described downstream signal, should
Relative frequency deviation η estimates ζ=η as sample clock frequency deviation.
6. a kind of user site equipment is it is characterised in that include：
Carrier wave frequency deviation calculates unit, and the downstream signal measuring and calculating for being sent according to the access point AP receiving obtains carrier wave frequency deviation
Frequency offset compensation element, for according to described carrier wave frequency deviationFrequency compensation is carried out to up data to be sent；Specifically for
When sending data, according toCarrier frequency compensation is carried out to up data to be sent；Wherein, u (n) is
User site upstream data time domain samples point to be sent, TsFor the theoretical baseband sample sampling interval；
Sampling clock frequency deviation calculates unit, for the downstream signal measuring and calculating sample clock frequency deviation being sent according to the AP receiving
ζ；
Clock frequency compensating unit, during for sampling to up data to be sent according to described sample clock frequency deviation ζ
Clock frequency compensation；Specifically for：Described up data to be sent is up-sampled, the sampling interval isTiRepresent and use
In the baseband sample sampling interval of family website, N is integer, represents up-sampling multiple；WillInclined as new sampling clock
Difference carries out time domain interpolation so that the equivalent sampling of sample is spaced apart after interpolationLow pass is carried out to described up data to be sent
Filtering and down-sampling are so that the equivalent sampling of described up data sample to be sent is spaced apart.
7. user site equipment as claimed in claim 6 it is characterised in that：
Described downstream signal includes synchronization preamble, and described synchronization preamble includes short training sequence and long training sequence；
Described carrier wave frequency deviation calculates unit, for carrying out to the downstream signal receiving postponing auto-correlation processing, using described short
Training sequence obtains preliminary frequency offset estimation result, obtains accurate frequency offset estimation result using described long training sequence
8. user site equipment as claimed in claim 7 it is characterised in that：
Described short training sequence includes first circulation prefix CP1 and multiple period 1 sequence, and described long training sequence includes
Two cyclic prefix CP 2 and multiple second round sequence；The length of described period 1 sequence is less than described second round sequence
Length.
9. user site equipment as claimed in claim 8 it is characterised in that：
Described short training sequence and described long training sequence respectively take an OFDM symbol.
10. user site equipment as claimed in claim 6 it is characterised in that：
Described sampling clock frequency deviation calculates unit, according to described carrier wave frequency deviationCalculate relative frequency deviationWherein fcFor described
The carrier frequency of downstream signal, this relative frequency deviation η is estimated ζ=η as sample clock frequency deviation.
11. user site equipment as any one of claim 6-10 it is characterised in that：Described clock frequency compensates
Unit, including：
Up-sampling module, described up data to be sent is up-sampled, the sampling interval isTiFor user site
In the baseband sample sampling interval, N is up-sampling multiple, and N is integer；
Interpolating module, for inciting somebody to actionCarry out time domain interpolation as new sampling clock deviation so that sample etc. after interpolation
Effect the sampling interval be
Low-pass filtering module, for carrying out low-pass filtering to the sample data after interpolation；
Down sample module, for carrying out down-sampling to the data after low-pass filtered so that upstream data sample to be sent
Equivalent sampling is spaced apart.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110237054.6A CN102694762B (en) | 2011-03-25 | 2011-08-18 | Method for realizing synchronization of carrier and sampling clock, and user site device |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110074379 | 2011-03-25 | ||
| CN2011100743797 | 2011-03-25 | ||
| CN201110074379.7 | 2011-03-25 | ||
| CN201110237054.6A CN102694762B (en) | 2011-03-25 | 2011-08-18 | Method for realizing synchronization of carrier and sampling clock, and user site device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102694762A CN102694762A (en) | 2012-09-26 |
| CN102694762B true CN102694762B (en) | 2017-02-22 |
Family
ID=46860049
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110237054.6A Active CN102694762B (en) | 2011-03-25 | 2011-08-18 | Method for realizing synchronization of carrier and sampling clock, and user site device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102694762B (en) |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103152767B (en) * | 2013-03-19 | 2016-02-17 | 武汉中软通科技有限公司 | For the uplink synchronous detection method of frequency offset resistant in a kind of wireless communication system |
| CN103580766B (en) * | 2013-11-22 | 2017-02-08 | 中国电子科技集团公司第五十四研究所 | Frequency control method of heterogeneous station type of multi-frequency TDMA (time division multiple access) satellite communication system |
| CN105659549A (en) | 2014-08-06 | 2016-06-08 | 华为技术有限公司 | Method and apparatus for transmitting uplink information in multi-user multiple-input multiple-output system |
| CN104410599B (en) * | 2014-12-22 | 2017-11-07 | 武汉邮电科学研究院 | Time and frequency deviation correction method in a kind of point-to-multipoint wireless OFDM communication system |
| CN105813141A (en) * | 2014-12-31 | 2016-07-27 | 中兴通讯股份有限公司 | Downlink multiuser transmission method and device |
| CN107204945B (en) * | 2016-03-18 | 2020-11-03 | 富士通株式会社 | Frequency difference estimation device, channel interval estimation device, method and system |
| CN107204944B (en) * | 2016-03-18 | 2020-11-03 | 富士通株式会社 | Transmission sequence generation device, training sequence synchronization device, channel interval estimation method, and channel interval estimation system |
| WO2018059782A1 (en) * | 2016-09-30 | 2018-04-05 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Telegram splitting-based localization |
| US10848361B2 (en) * | 2017-12-08 | 2020-11-24 | Qualcomm Incorporated | Carrier independent signal transmission and reception |
| CN107948111B (en) * | 2017-12-13 | 2020-08-14 | 北京智芯微电子科技有限公司 | Sampling frequency offset correction method of OFDM system |
| CN108377543B (en) * | 2018-01-09 | 2021-01-08 | 北京智联安科技有限公司 | NBIoT terminal clock synchronization method and device |
| CN110536405B (en) * | 2018-05-25 | 2021-08-03 | 华为技术有限公司 | Synchronization method and access point |
| CN110943948B (en) * | 2018-09-21 | 2023-07-21 | 中国移动通信有限公司研究院 | Information configuration method and equipment |
| CN111163027B (en) * | 2019-12-26 | 2022-05-31 | 哈尔滨海能达科技有限公司 | Synchronization detection method and device |
| CN113225802B (en) * | 2021-03-17 | 2022-05-10 | 传世智能科技(南通)有限公司 | Timing synchronization method for NOMA uplink |
| CN113794670B (en) * | 2021-09-18 | 2023-08-22 | 上海航天电子通讯设备研究所 | Demodulation system of 16QAM signal in VDES |
| CN113950140B (en) * | 2021-10-15 | 2023-06-30 | 广东电网有限责任公司江门供电局 | Clock synchronization method and system for low-voltage distribution network Internet of things |
| CN114928408B (en) * | 2022-04-26 | 2024-04-09 | 南京金阵微电子技术有限公司 | TDD communication system, method and transceiver chip |
| CN115174338B (en) * | 2022-09-06 | 2022-11-11 | 北京思凌科半导体技术有限公司 | Frequency deviation determination method, frequency deviation determination device, storage medium and electronic equipment |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1881823A (en) * | 2005-06-17 | 2006-12-20 | 美国博通公司 | Method for correcting sampling frequency offset of a data packet in a communications system |
| CN101039154A (en) * | 2006-03-15 | 2007-09-19 | 大唐移动通信设备有限公司 | Method for obtaining transceiver channel transmission time of user terminal |
| CN101299737A (en) * | 2007-04-30 | 2008-11-05 | 华为技术有限公司 | Synchronous estimation method and system for orthogonal frequency division multiplexing technique |
| CN101944977A (en) * | 2009-07-06 | 2011-01-12 | 清华大学 | Reception diversity method and system thereof |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7639748B2 (en) * | 2005-08-30 | 2009-12-29 | Via Technologies, Inc. | Method and circuit for fine timing synchronization in the orthogonal frequency division multiplexing baseband receiver for IEEE 802.11a/g wireless LAN standard |
| US8537931B2 (en) * | 2008-01-04 | 2013-09-17 | Qualcomm Incorporated | Methods and apparatus for synchronization and detection in wireless communication systems |
| EP2141877A1 (en) * | 2008-06-30 | 2010-01-06 | THOMSON Licensing | Receiver and method for frequency offset estimation based on correlation techniques |
-
2011
- 2011-08-18 CN CN201110237054.6A patent/CN102694762B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1881823A (en) * | 2005-06-17 | 2006-12-20 | 美国博通公司 | Method for correcting sampling frequency offset of a data packet in a communications system |
| CN101039154A (en) * | 2006-03-15 | 2007-09-19 | 大唐移动通信设备有限公司 | Method for obtaining transceiver channel transmission time of user terminal |
| CN101299737A (en) * | 2007-04-30 | 2008-11-05 | 华为技术有限公司 | Synchronous estimation method and system for orthogonal frequency division multiplexing technique |
| CN101944977A (en) * | 2009-07-06 | 2011-01-12 | 清华大学 | Reception diversity method and system thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102694762A (en) | 2012-09-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102694762B (en) | Method for realizing synchronization of carrier and sampling clock, and user site device | |
| AU2005208694B2 (en) | Timing estimation in an OFDM receiver | |
| US8031586B2 (en) | Method and apparatus for transmitter timing adjustment | |
| CN103281284B (en) | For adjusting the method and the travelling carriage thereof that send timing and send grouping continuously | |
| AU2009210457B2 (en) | Frequency error estimation | |
| WO2013040999A1 (en) | Combined estimation method for time deviation and frequency deviation | |
| CN101267419B (en) | A time advance adjustment method and device for OFDM symbol timing | |
| CN103475614B (en) | Method and device for frequency offset estimation and compensation | |
| EP3729755B1 (en) | Method and device for transmitting ofdm signal, and method and device for receiving ofdm signal | |
| US20060198472A1 (en) | Transmission system, transmitter device, and receiver device | |
| WO2012130090A1 (en) | Ofdm-based method and system for transmitting data | |
| CN102394855A (en) | Sampling clock frequency compensation method and device | |
| US10771297B2 (en) | Method and device for multi-service transmission with FC-OFDM modulation and corresponding receiver | |
| WO2011006114A1 (en) | Frequency tracking loop for wireless communications | |
| CN102497347B (en) | Time delay adjusting method and system for wireless communication system | |
| CN101369882A (en) | Frequency synchronization method based on pre-correction of sending terminal | |
| CN105490981A (en) | Device and method for adaptive compensation of SCO in LTE system | |
| CN102420793A (en) | Tracking control method of digital communication receiver time and carrier frequency synchronization | |
| CN102726018B (en) | Method, apparatus and system for duplexing transmission of multi-carrier orthogonal frequency division multiplexing | |
| CN103974407B (en) | A kind of mapping method, system and the device of smart synchronized tracking reference symbol | |
| CN114423072A (en) | Apparatus and method for wireless communication | |
| CN105282077A (en) | Uplink frequency offset correction method for LTE system | |
| CN102695264B (en) | A kind of method realizing time synchronized and wireless communication system | |
| Chen et al. | ASIC implementation of an OFDM baseband transceiver for HINOC | |
| CN102695264A (en) | Method for realizing time synchronization and wireless communication system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| ASS | Succession or assignment of patent right |
Owner name: BEIJING NUFRONT MOBILE MULTIMEDIA TECHNOLOGY CO., Free format text: FORMER OWNER: BEIJING NUFRONT WIRELESS TECHNOLOGY CO., LTD. Effective date: 20130422 |
|
| C41 | Transfer of patent application or patent right or utility model | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20130422 Address after: 100084 Beijing, Zhongguancun, East Road, No. 1, Tsinghua Science and Technology Park, building science and Technology Park, building No. 8, block A, floor 16 Applicant after: BEIJING NUFRONT MOBILE MULTIMEDIA TECH. Co.,Ltd. Address before: 100084 Beijing, Zhongguancun, East Road, No. 1, Tsinghua Science and Technology Park, building science and Technology Park, building No. 8, block A, floor 16 Applicant before: BEIJING NUFRONT WIRELESS TECH. Co.,Ltd. |
|
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20180320 Address after: 100084 Beijing, Zhongguancun East Road, No. 1, Tsinghua Science and Technology Park, science and technology building, block A, floor, layer 16 Patentee after: BEIJING PUJIXIN TECHNOLOGY CO.,LTD. Address before: 100084 Beijing, Zhongguancun, East Road, No. 1, Tsinghua Science and Technology Park, building science and Technology Park, building No. 8, block A, floor 16 Patentee before: BEIJING NUFRONT MOBILE MULTIMEDIA TECH. Co.,Ltd. |
|
| CP01 | Change in the name or title of a patent holder | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 100084 16 Floors, Block A, Science and Technology Building, Tsinghua Science Park, No. 1 East Zhongguancun Road, Haidian District, Beijing Patentee after: New Shoreline (Beijing) Science and Technology Group Co.,Ltd. Address before: 100084 16 Floors, Block A, Science and Technology Building, Tsinghua Science Park, No. 1 East Zhongguancun Road, Haidian District, Beijing Patentee before: Beijing New Shoreline Technology Co.,Ltd. Address after: 100084 16 Floors, Block A, Science and Technology Building, Tsinghua Science Park, No. 1 East Zhongguancun Road, Haidian District, Beijing Patentee after: Beijing New Shoreline Technology Co.,Ltd. Address before: 100084 16 Floors, Block A, Science and Technology Building, Tsinghua Science Park, No. 1 East Zhongguancun Road, Haidian District, Beijing Patentee before: BEIJING PUJIXIN TECHNOLOGY CO.,LTD. |