CN1731715A - CDMA system access channel frequency deviation estimating method - Google Patents
CDMA system access channel frequency deviation estimating method Download PDFInfo
- Publication number
- CN1731715A CN1731715A CNA2004100416507A CN200410041650A CN1731715A CN 1731715 A CN1731715 A CN 1731715A CN A2004100416507 A CNA2004100416507 A CN A2004100416507A CN 200410041650 A CN200410041650 A CN 200410041650A CN 1731715 A CN1731715 A CN 1731715A
- Authority
- CN
- China
- Prior art keywords
- frequency deviation
- dfn
- compensate
- leading
- demodulation
- 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.)
- Granted
Links
Images
Landscapes
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
The invention discloses a method for evaluating frequency deviation when code division multiple access systems switch in communication channels. The inventive method comprises the steps of: (1) during the process of switching in, using preset different frequency deviation compensation values dF1, dF2,..., dFn-1, dFn to leading modulation and getting different leading amplitude A(dF1), A(dF2),..., and A(dFn-1), A(dFn)during compensating, wherein n>=2; (2) calculating the ratio of the amplitude values get from step (1) Aratei=A(dFi)/A(dFi+1), wherein i=1...n-1; (3) according to the ratio of leading modulation amplitude and the differential value of preset frequency deviation FStepi function DeltaF and the ith frequency deviation compensation value dFi, getting the (n-1)th frequency deviation; (4) getting the evaluating frequency deviation value by averaging; (5) making frequency deviation compensation to switched-in messages.
Description
Technical field
The present invention relates to communication technical field, the especially estimation of the frequency shift (FS) of access channel in the code division multi-address radio communication system.
Background technology
In code division multi-address radio communication system, because the influence of the precision difference of radio-frequency (RF) local oscillator and the Doppler effect when mobile, the frequency of the centre carrier frequency of the signal that the base station receives and the radio-frequency (RF) local oscillator of base station has certain deviation, this frequency departure reaches more than 1000 hertz (Hz) sometimes, is in usually within the positive and negative 1500Hz scope.If this frequency departure (abbreviation frequency deviation) is not compensated, will cause demodulation performance to descend significantly.For this reason, we need estimate how many this frequency deviations is on earth, and carry out suitable compensate of frequency deviation, to guarantee due receptivity.In order to want access network to communicate, travelling carriage sends a period of time preface information usually earlier, and after the base station was received this preface information and confirmed, travelling carriage can be launched the access message of a period of time, has wherein comprised the important parameter information that communication is set up.Receive after these message the base station, could successfully set up for the communication link of this travelling carriage special use.Usually, top process is called access procedure.After setting up dedicated communication link, the base station can receive enough data of travelling carriage and carry out frequency offset estimating.And in access procedure, then often do not have enough data to carry out frequency offset estimating, thereby the demodulation performance that inserts message may can not get guaranteeing.The compensate of frequency deviation that inserts message just becomes a more special problem.
In present technology, often when separating preface information, employing fixedly installs a plurality of compensate of frequency deviation values and carries out compensate of frequency deviation and demodulation simultaneously, judge the leading energy maximum of which compensate of frequency deviation value demodulation result then, just in separating the process that inserts message, carry out compensate of frequency deviation with this compensate of frequency deviation value.Yet because leading demodulation need expend a large amount of software and hardware resources, the compensate of frequency deviation value that sets in advance can not be too many, is generally 2 to 4 different compensate of frequency deviation values.Like this, the interval of adjacent compensate of frequency deviation value reaches 300 to 900Hz, and such precision is very coarse, and the compensate of frequency deviation in the demodulating process of access message can not get high-quality assurance.
Summary of the invention
Technical problem to be solved by this invention is: insert the coarse problem of compensate of frequency deviation precision in the message demodulation process.
The present invention solves the problems of the technologies described above the technical scheme that is adopted to be: the amplitude size relativeness and the frequency bias properties that solve according to each the default frequency deviation in the leading demodulation, the frequency deviation of mobile station signal compared accurately estimate, and insert compensate of frequency deviation in the message demodulation process with this frequency offset estimating value.Concrete scheme is:
(1) in access procedure, the n that usefulness is preset different compensate of frequency deviation value dF1, a dF2 ..., dFn-1, dFn carry out leading demodulation, the leading amplitude A (dF1) when obtaining different compensate of frequency deviation, A (dF2) ..., A (dFn-1), A (dFn), wherein n 〉=2;
(2) default frequency deviation demodulation obtains amplitude according to the difference that obtains in the step (1), calculates their ratio Aratei=A (dF
i)/A (dF
I+1), i=1 wherein ... n-1;
(3) according to leading function DeltaF and i compensate of frequency deviation value dF that separates modulation ratio Aratei and default frequency deviation difference FStepi
iDifference obtain n-1 exemplary frequency deviation values;
(4) exemplary frequency deviation values is asked on average obtained the frequency deviation estimated;
(5) carry out compensate of frequency deviation with the frequency deviation that estimates to inserting message.
Another technical scheme of the present invention is, the energy size relativeness and the frequency bias properties that solve according to each the default frequency deviation in the leading demodulation, frequency deviation to mobile station signal compares estimation accurately, and inserting compensate of frequency deviation in the message demodulation process with this frequency offset estimating value, its concrete treatment step is identical with the above-mentioned range value that utilizes.
Beneficial effect of the present invention is: the precision of frequency offset estimating has original hundreds of hertz to bring up to tens hertz, has improved an order of magnitude.Thereby greatly reduce the access message demodulation performance loss that frequency deviation is brought.The present invention can be applied in the base station or travelling carriage of various code division multiple address communication systems.
Description of drawings
Fig. 1 is the access procedure signal schematic representation;
Fig. 2 is frequency deviation and the leading graph of a relation of separating modulation;
Fig. 3 is the leading functional relation of separating modulation ratio and true frequency deviation size of two compensate of frequency deviation;
Fig. 4 is an exemplary plot of compensate of frequency deviation value and leading demodulation relative amplitude;
Fig. 5 is the relation of frequency offset estimation accuracy and demodulation performance;
Fig. 6 is the inventive method flow chart.
Embodiment
The first step: carry out theory analysis, draw the default frequency deviation dF1 of two differences, and leading amplitude (or energy) the ratio Arate that dF2 solves and the functional relation DeltaF of " the true frequency deviation Foffset of dF1-signal " (Arate, FStep), wherein FStep=dF2-dF1 promptly satisfies
Foffset＝dF1-DeltaF(Arate，dF2-dF1)；
A plurality of if desired default frequency deviations, and adopt FStep all the same in calculating, then (Arate FStep) can turn to one dimension function DeltaF (Arate) to DeltaF.4 frequency deviations for example uniformly-spaced are set, and the modulation ratio of separating that utilizes adjacent frequency deviation to obtain calculates.
This step just can finish when system design.
Second step: in access procedure, the default individual different compensate of frequency deviation value dF1 of n (n is more than or equal to 2), dF2 ..., dFn-1, dFn carry out leading demodulation, leading amplitude (or energy) A (dF1), the A (dF2) when obtaining different compensate of frequency deviation ..., A (dFn_1), A (dFn).
The 3rd step: the amplitude (or energy) that the default frequency deviation of difference that obtains according to second step solves, calculate their ratio, for example Arate1=A (dF1)/A (dF2).If there is frequency deviation also can calculate a plurality of ratios, for example more than two:
Arate2＝A(dF2)/A(dF3)
Araten-1＝A(dFn-1)/A(dFn)
This step obtains one or more ratios.
The 4th step: utilize the result in the 3rd step, according to function DeltaF (Arate FStep) estimates Foffset, for example:
Foffset1=dF1-DeltaF (Arate1, FStep1), FStep1=dF2-dF1 wherein;
Foffset2=dF2-DeltaF (Arate2, FStep2), FStep2=dF3-dF2 wherein;
Foffsetn-1=dFn-1-DeltaF (Araten-1, Fstepn-1), Fstepn-1=dFn-dFn-1 wherein;
If this step has only been calculated a Foffset1 (being n=2), then Foffset=Foffset1; If this step is calculated a plurality of functional values (being n＞2), then these values are asked and are on average obtained Foffset:
Foffset＝(Foffset1+Foffset2+...+Foffsetn-1)/(n-1)；
The 5th step: carry out compensate of frequency deviation to inserting message with the frequency deviation Foffset that estimates.
With embodiment the present invention is described in further detail with reference to the accompanying drawings below.According to these accompanying drawings, the technical staff in same field can be easy to realize the present invention.Following embodiment with the amplitude after the signal demodulation but not the ratio of energy is example as frequency offset estimating, and is an example with two default frequency deviation values.For estimate its method processing procedure all fours with energy ratio.
Fig. 1 is the signal schematic representation of access procedure.One section targeting signal was arranged before this.Because at this moment the base station does not have any frequency deviation information of travelling carriage, base station can preset a plurality of different compensate of frequency deviation values to go to separate leading, if success separates out leading, the base station can be launched an expression " permission access " message and be sent to travelling carriage.Travelling carriage sends one section access message that comprises access parameter then.In the WCDMA system, the length of targeting signal is 4096 chips, and each chip time is Tc=1/3840000 second, and the length that inserts message is 10 milliseconds or 20 milliseconds, i.e. 38400 chips or 76800 chips.
Fig. 2 is the functional relation that frequency deviation is conciliate modulation.According to theory analysis, the centre frequency of supposing received signal is fr, and local frequency is f0, both frequency deviation foffset=fr-f0, and then the pass of foffset and restituted signal amplitude A is:
A＝sinc(Ncoh×Tc×foffset)
Wherein function sinc is defined as:
Sinc (x)=sin (pi * x)/(pi * x), sin is a SIN function, pi=3.14159 is here with the leading example that is demodulated among the WCDMA, coherent integration length when supposing the demodulation targeting signal is Ncoh=1024 or 2048 or 4096 chips, the signal amplitude that integration comes out during no frequency deviation is 1, and then the relation of received signal amplitude and frequency deviation as shown in Figure 2.As seen from the figure, frequency deviation is big more, and amplitude is more little, and performance loss is just big more.
Fig. 3 is leading functional relation DeltaF (Arate, exemplary plot FStep) of separating modulation ratio Arate and " difference (dF1-Foffset) of first compensate of frequency deviation value and true frequency deviation Foffset " size of two compensate of frequency deviation dF1, dF2.From theory analysis, both sides relation is:
Arate＝sinc(Ncoh×Tc×(dF1-Foffset))/sinc(Ncoh×Tc×(dF1-Foffset)+Fstep)
So, Arate and (dF1-Foffset) good corresponding relationship arranged.
Among Fig. 3, abscissa is the leading modulation ratio Arate that separates of two compensate of frequency deviation, and ordinate is the poor of first compensate of frequency deviation value and real frequency deviation value, promptly
(dF1-Foffset)＝DeltaF(Arate，FStep)
Separating when leading, the compensate of frequency deviation value that several differences (at least two) generally can be set in the system is carried out demodulation simultaneously.Suppose wherein two default frequency deviation value dF1 and dF2, satisfy:
dF1+FStep＝dF2
Wherein FStep gets up to a hundred hertz usually, and its span is 200Hz～1000Hz, such as getting 200Hz, 400Hz, 600Hz, 800Hz etc.Then
Frequency offset estimating value Foffset=dF1-DeltaF (Arate, FStep).
As seen, from then in the functional relation of figure, can be by Arate, dF1, dF2 estimate frequency deviation Foffset.
Fig. 4 is an exemplary plot of compensate of frequency deviation value and leading demodulation relative amplitude.Suppose that we have preset two compensate of frequency deviation value dF1=-400Hz, dF2=400Hz goes to separate leading, and both frequency deviations are FStep=800Hz at interval.And the real frequency deviation Foffset=-100 of targeting signal and local oscillator if promptly the compensate of frequency deviation value is-100, then can obtain maximum reception amplitude 1.With two compensate of frequency deviation value dF1, the modulation of separating that dF2 obtains is:
A(dF1)＝0.958；
A(dF2)＝0.887；
Arate1=0.958/0.887=1.08 then;
Searching the curve of corresponding frequency deviation interval 800Hz among Fig. 3, is 1.08 o'clock at abscissa, and ordinate is-300Hz, so the frequency deviation that can estimate should be:
Foffset＝dF1-DeltaF(Arate1，FStep1)
＝-400-(-300)
＝-100Hz；
This estimated result and real frequency deviation are coincide, and error can be very little.The demodulation that inserts message with this compensate of frequency deviation value can obtain best demodulation effect.
And if use existing conventional art because A (400) is greater than A (400), just to insert message with-400Hz carries out compensate of frequency deviation and real frequency offset error reaches 300Hz.
Fig. 5 is frequency offset estimation accuracy and the relation that inserts the message demodulation performance.As seen from the figure, when frequency offset error reaches 300Hz, the loss of 0.37dB is arranged.If frequency offset error reaches 100Hz, the about 0.04dB of decreased performance, and frequency offset error is during less than 50Hz, performance loss is less than 0.01dB, almost not loss.This shows that the inventive method can accurately be estimated frequency deviation to significantly improve receptivity.
Fig. 6 is the flow chart of the inventive method.5 steps in 5 square frame corresponding method.
As can be seen, according to the present invention, the frequency offset estimation accuracy of access procedure can improve an order of magnitude, and the performance that inserts message demodulation can be significantly improved.
Claims (6)
1. a CDMA system cut-in channel frequency deviation estimating method is characterized in that, this method may further comprise the steps:
(1) in access procedure, the n that usefulness is preset different compensate of frequency deviation value dF1, a dF2 ..., dFn-1, dFn carry out leading demodulation, the leading amplitude A (dF1) when obtaining different compensate of frequency deviation, A (dF2) ..., A (dFn-1), A (dFn), wherein n 〉=2;
(2) default frequency deviation demodulation obtains amplitude according to the difference that obtains in the step (1), calculates their ratio Aratei=A (dF
i)/A (dF
I+1), i=1 wherein ... n-1;
(3) according to leading function DeltaF and i compensate of frequency deviation value dF that separates modulation ratio Aratei and default frequency deviation difference FStepi
iDifference obtain n-1 exemplary frequency deviation values;
(4) exemplary frequency deviation values is asked on average obtained the frequency deviation estimated;
(5) carry out compensate of frequency deviation with the frequency deviation that estimates to inserting message.
2. method according to claim 1 is characterized in that, when n=2, only obtains an exemplary frequency deviation values, and just can obtain this exemplary frequency deviation values without the averaging process of execution in step (4) this moment is the true deviation value.
3. method according to claim 1 and 2 is characterized in that, the default frequency deviation difference FStepi=dF described in the step (3)
I+1-dF
i
4. method according to claim 3, it is characterized in that, by default two different frequency deviation dF1, dF2, through theory analysis, (obtain the functional relation DeltaF that separates modulation ratio Arate and " the true frequency deviation Foffset of dF1-signal " in the step (3) Ncoh * Tc * (dF1-Foffset)+Fstep) from formula Arate=sinc (Ncoh * Tc * (dF1-Foffset))/sinc, sinc in the formula (x)=sin (pi * x)/(pi * x), sin is a SIN function, pi equals 3.14159, Fstep=dF2-dF1, Ncoh=1024 or 2048 or 4096 chips, Tc=1/3840000 second.
5. method according to claim 4 is characterized in that the span of Fstep is 200Hz～1000Hz.
6. a CDMA system cut-in channel frequency deviation estimating method is characterized in that, this method may further comprise the steps:
(1) in access procedure, the n that usefulness is preset different compensate of frequency deviation value dF1, a dF2 ..., dFn-1, dFn carry out leading demodulation, leading energy value E (dF1), the E (dF2) when obtaining different compensate of frequency deviation ..., E (dFn-1), E (dFn), wherein n 〉=2;
(2) default frequency deviation demodulation obtains energy according to the difference that obtains in the step (1), calculates their ratio Eratei=E (dF
i)/E (dF
I+1), i=1 wherein ... n-1;
(3) according to function DeltaF and i compensate of frequency deviation value dF of leading demodulation energy ratio Eratei and default frequency deviation difference FStepi
iDifference obtain n-1 exemplary frequency deviation values;
(4) exemplary frequency deviation values is asked on average obtained the frequency deviation estimated;
(5) carry out compensate of frequency deviation with the frequency deviation that estimates to inserting message.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200410041650A CN100589354C (en) | 2004-08-04 | 2004-08-04 | The CDMA system cut-in channel frequency deviation estimating method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200410041650A CN100589354C (en) | 2004-08-04 | 2004-08-04 | The CDMA system cut-in channel frequency deviation estimating method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1731715A true CN1731715A (en) | 2006-02-08 |
| CN100589354C CN100589354C (en) | 2010-02-10 |
Family
ID=35964025
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200410041650A Expired - Fee Related CN100589354C (en) | 2004-08-04 | 2004-08-04 | The CDMA system cut-in channel frequency deviation estimating method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100589354C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102244625A (en) * | 2010-05-14 | 2011-11-16 | 中兴通讯股份有限公司 | Signal receiving method and device |
| CN104184524A (en) * | 2013-05-21 | 2014-12-03 | 电信科学技术研究院 | Frequency calibration method and device |
| CN106304272A (en) * | 2015-06-26 | 2017-01-04 | 深圳市中兴微电子技术有限公司 | A kind of rapid frequency-sweeping method, device and terminal |
-
2004
- 2004-08-04 CN CN200410041650A patent/CN100589354C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102244625A (en) * | 2010-05-14 | 2011-11-16 | 中兴通讯股份有限公司 | Signal receiving method and device |
| CN104184524A (en) * | 2013-05-21 | 2014-12-03 | 电信科学技术研究院 | Frequency calibration method and device |
| CN104184524B (en) * | 2013-05-21 | 2016-09-14 | 电信科学技术研究院 | A kind of transmitting frequency calibration method and device |
| CN106304272A (en) * | 2015-06-26 | 2017-01-04 | 深圳市中兴微电子技术有限公司 | A kind of rapid frequency-sweeping method, device and terminal |
| CN106304272B (en) * | 2015-06-26 | 2019-10-18 | 深圳市中兴微电子技术有限公司 | A kind of rapid frequency-sweeping method, apparatus and terminal |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100589354C (en) | 2010-02-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1165118C (en) | Method and apparatus for determining closed lamp power control set point in wireless packet and communication system | |
| CN1248535C (en) | Method and system for performing handoff in wireless communication system, such as hard handoff | |
| CN1173493C (en) | Appts. and method for reporting service load to mobile station in mobile telecommunication system | |
| CN1135725C (en) | Search window delay tracking in code division multiple access communication systems | |
| CN1213562C (en) | Method and apparatus for receiving signal in digital radio frequency communication system | |
| CN1084089C (en) | Improved channel estimation in communication system | |
| CN1166080C (en) | Channel estimation device and method for radio system | |
| CN101076964A (en) | Channel estimator with spread channel bandwidth | |
| CN1225906C (en) | Method for making synchronization by utilizing time domain spread spectrum beacon in digital video broadcast | |
| CN1151622C (en) | Pilot channel tracking method based on multipath channel energy window gravity center tracking loop | |
| CN1731715A (en) | CDMA system access channel frequency deviation estimating method | |
| CN1901692A (en) | Method for estimating the time of arrival of an access burst (ab), ab-detector and a base transceiver station (BTS) | |
| CN1716817A (en) | Method for realizing user's equipment downward synchronization in TD-SCDMA mobile communication system | |
| CN101076002A (en) | Method and apparatus for acquiring circulating prefix-length information | |
| CN1691659A (en) | A method for synchronization in OFDM system | |
| CN1398065A (en) | Method for increasing the estimation performance to carrier frequency deviation of OFDM communication system | |
| CN1159874C (en) | SIR estimating method and device for WCDMA system | |
| CN1114292C (en) | Tracking method and device in CDMA communication system containing pilot channel | |
| CN1909413A (en) | Method for transmitting variable-speed data in time slot CDMA cellular system | |
| CN1114291C (en) | Frequency deviation estimation method applicable to code division multiple address access system | |
| CN1753397A (en) | The transmission method of training symbol and method for synchronous | |
| CN101039300A (en) | Synchronous timing method | |
| CN1188957C (en) | Channel estimating method and apparatus thereof | |
| CN1976255A (en) | Method for realizing user normal communication under high-speed moving | |
| CN101043499A (en) | Method and equipment for capturing transmission signal of channel in OFDM system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20100210 Termination date: 20170804 |