CN101582870A - Method and device for realizing synchronization - Google Patents

Abstract

The invention discloses a method for realizing synchronization, which comprises the following steps: converting two received continuous time-domain distance measuring signals into frequency-domain distance measuring signals so as to obtain a first frequency-domain distance measuring signal and a second frequency-domain distance measuring signal; detecting distance measuring codes which correspond to the two continuous time-domain distance measuring signals; respectively multiplying the distance measuring codes with corresponding elements of the first frequency-domain distance measuring signal and the second frequency-domain distance measuring signal so as to obtain a first correlation sequence and a second correlation sequence; carrying out conjugate multiplication on the corresponding elements of the first correlation sequence and the second correlation sequence so as to obtain a frequency offset; carrying out the conjugate multiplication on corresponding adjacent elements of the first correlation sequence and the second correlation sequence and subtracting the frequency offset from a multiplication result so as to obtain a time offset; and utilizing the time offset to carry out synchronous calibration. The invention also discloses a device for realizing synchronization. The invention reduces the influence of the frequency offset on the time offset and the error of the time offset and improves the synchronous precision.

Description

Synchronous implementation method and device

Technical field

The present invention relates to the communications field, relate in particular to a kind of synchronous implementation method and device.

Background technology

OFDM (Orthogonal Frequency Division Multiplexing abbreviates OFDM as) is the high speed transmission technology under a kind of wireless environment.The frequency response curve great majority of wireless channel all are the curves of non-flat forms, and the main thought of OFDM technology is exactly in frequency domain allocated channel is divided into a plurality of orthogonal sub-channels, on each subchannel, use a subcarrier to modulate, and each subcarrier parallel transmission.Like this, although total channel be the curve of non-flat forms, and have frequency selectivity, but each subchannel is a relatively flat, what carry out on each subchannel is narrow band transmission, and signal bandwidth is less than the responsive bandwidth of channel, the interference between the erasure signal waveform so greatly.Because be mutually orthogonal between the carrier wave of each subchannel in ofdm system, their frequency spectrum is overlapped, has so not only reduced the phase mutual interference between subcarrier, and has improved the availability of frequency spectrum.

OFDM has many advantages for high-rate wireless and wire communication, therefore it has been widely used in IEEE802.11a/g WLAN (wireless local area network) (Wireless Local AreaNetwork, abbreviate WLAN as), IEEE802.15 wireless personal-area network (WirelessPersonal Area Network abbreviates WPAN as) and IEEE802.16 wireless MAN (WMAN).And, OFDM can with code division multiple access (Code Division MultipleAccess, abbreviate CDMA as), super bandwidth (Ultra Wide Band abbreviates UWB as) and multiple-input, multiple-output (Multiple-Input Multiple-Out abbreviates MIMO as) technology combine.So OFDM can play important effect in current with following communication system.

The defective of OFDM is mainly reflected in, ofdm system is very responsive to the sign synchronization mistake, the sign synchronization mistake is that side-play amount is poor because symbol timing estimation position and the inconsistent symbol that causes of physical location are fixed time, the phase deviation that it brings will increase the weight of intersymbol interference (Inter-Symbol-Interference, abbreviate ISI as), be intersymbol interference, can make that like this error rate increases greatly, therefore need accurate more sign synchronization.

In the 802.16e wireless communication system, the long-distance user stands (Subscriber Station abbreviates SS as), and for example honeycomb or mobile phone arrive base station (Base Station abbreviates BS as) or " up link " access network by sending and insert signal.This inserts signal and realizes important function, for example ask BS to carry out resource allocation, there is the SS that attempts access network in warning BS, and initiates to allow BS to measure the processing of some parameter of SS, wherein, parameter comprises and propagates the time offset cause, frequency error, transmitted power or the like.Wherein, keep and regulate these parameters and share to guarantee the noiseless of uplink resource (for example BS).Distribute to the data service that the scheduling resource of SS sends unlike common use, but send the access signal that is used for SS and often this processing is referred to as to insert at random in spontaneous mode.This processing can also be thought initial ranging (ranging), because described access signal can help BS to measure and the propagation distance of SS, it is the scope between the two, so that can regulate its transmitting time to guarantee signal from all SS, i.e. the uplink timing sign synchronization in the base station sign synchronization.

Each SS can use initial ranging to transmit to finish for the first time the sign synchronization with system.In order effectively to carry out the ranging transmission, each user can select a ranging code (ranging code) at random from the binary code of one group of regulation, wherein, the ranging sequence sets that has disposed in the backstage of BS for the SS initial ranging closes, and each sign indicating number has 144.These ranging code are modulated on the carrier wave of ranging channel by binary phase shift keying (BPSK), each carrier wave 1 bit.Initialization ranging can realize on two continuous symbols.The ranging channel should use identical ranging sign indicating number during each symbol, does not have phase discontinuity (discontinuity) at two intersymbols.

Fig. 1 is the time-domain description of initial ranging transmission, takes following make: form two identical OFDM symbols earlier; Add Cyclic Prefix (CP) in first OFDM symbol beginning, promptly equal the waveform of the CP length of first OFDM symbol ending place; Be that second OFDM symbol ending adds protection (guard interval) at interval, promptly equal the waveform of the CP length of first OFDM symbol beginning place.

SS is after having caught descending sign synchronization and uplink parameter, selection Ranging time slot that should be at random (using binary system brachymemma exponentiation algorithm to avoid possible heavily collision) is as the time of carrying out ranging, then from initialization ranging sign indicating number territory at random ranging sign indicating number of selection and be transferred to BS as a CDMA sign indicating number.

BS can not distinguish it is which SS has sent the ranging application, therefore in the reception of success after the ranging sign indicating number, BS need broadcast a ranging response message, comprising the ranging sign indicating number and the ranging time slot (for example OFDM symbolic number, subchannel etc.) that receive.The SS that sends the ranging sign indicating number utilizes its ranging application that judged whether the ranging response message correspondence received of these information.The Ranging response message has comprised the adjustment information (for example time, power and possible frequency correction) and the state description of all needs,, carries out up initial access sign synchronization that is.

At present, the method for many up initial access sign synchronization has been arranged, comprised that time domain is relevant, frequency domain relevant, difference algorithm and adjacent carrier conjugate multiplication method.Wherein, time domain is relevant, frequency domain is relevant, difference algorithm all is to utilize the relevant peaks that obtains to determine the time offset of relative users, and this relevant peaks has maximum dynamic value.Dynamic value is meant the main peak and the second peak-to-peak amplitude difference, and the big more generation mistake of dynamic value police's probability is just more little; And relevant peaks obtains by relevant and inverse-Fourier transform operation, and amount of calculation is bigger, takies a lot of system resources.Adjacent carrier conjugate multiplication method has been ignored the influence of frequency shift (FS), but under the state of user's high-speed mobile, Doppler frequency shift will make the user have bigger frequency offset, adopts the method for prior art, the time offset that estimates will not be no inclined to one side, and error is very big.

Summary of the invention

Consider the bigger problem of error of time offset in the synchronous implementation method that exists in the correlation technique and propose the present invention, for this reason, main purpose of the present invention is to provide a kind of synchronous implementation method and device, to address the above problem.

According to an aspect of the present invention, provide a kind of synchronous implementation method.

Synchronous implementation method according to the embodiment of the invention comprises: two continuous time domain distance measuring signals that will receive are converted into the frequency domain distance measuring signal, obtain the first frequency domain distance measuring signal and the second frequency domain distance measuring signal; Detect two continuous pairing ranging codes of time domain distance measuring signal; Ranging code is multiplied each other with the corresponding element of the first frequency domain distance measuring signal and the second frequency domain distance measuring signal respectively, obtain first correlated series and second correlated series; Corresponding element conjugate multiplication with first correlated series and second correlated series obtains frequency offset; With the corresponding adjacent element conjugate multiplication of first correlated series with second correlated series, multiplied result is deducted frequency offset, obtain time offset; Utilize time offset to carry out same step calibration.

Wherein, the concrete operations that detect two continuous pairing ranging codes of time domain distance measuring signal are: select in the first frequency domain distance measuring signal and the second frequency domain distance measuring signal any one as reference frequency domain distance measuring signal; Will with reference to the coherent element of frequency domain distance measuring signal respectively with its frequency domain on the conjugation of adjacent backward element multiply each other, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain first with reference to mean value; With ranging code with multiply each other with reference to the corresponding element of frequency domain distance measuring signal, obtain a plurality of values, with each value of obtaining respectively with its conjugate multiplication, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain second with reference to mean value; With first with reference to mean value divided by second with reference to mean value, obtain with reference to mean value; Utilize the coefficient correlation between the ranging code to obtain the threshold value of finding range; Will with reference to mean value with the range finding threshold value compare, if with reference to mean value greater than the range finding threshold value, then with ranging code as two continuous pairing ranging codes of time domain distance measuring signal.

Preferably, utilize the above-mentioned first frequency domain distance measuring signal as reference frequency domain distance measuring signal.

Wherein, corresponding element conjugate multiplication with first correlated series and second correlated series, the operation that obtains frequency offset is specially: continuous item corresponding on the conjugation of utilizing the first correlated series continuous item and the second correlated series frequency domain multiplies each other, and obtains a plurality of product terms; A plurality of product terms are carried out phase adduction calculating mean value, and calculate the multiple angle of mean value, will answer the angle, obtain frequency offset divided by 2 π.

Wherein, with the corresponding adjacent element conjugate multiplication of first correlated series with second correlated series, multiplied result is deducted frequency offset, the operation that obtains time offset is specially: utilize continuous item adjacent backward on the conjugation of the second correlated series continuous item and the first correlated series frequency domain to multiply each other, obtain a plurality of product terms; A plurality of product terms are carried out phase adduction calculating mean value, and calculate the multiple angle of mean value, will answer the angle, the result who obtains is deducted frequency offset, multiply by the fast Fourier transform points N at last and obtain time offset divided by 2 π.

According to a further aspect in the invention, provide a kind of synchronous implement device.

Implement device comprises synchronously according to an embodiment of the invention: modular converter, and two continuous time domain distance measuring signals that are used for receiving are converted into the frequency domain distance measuring signal, obtain the first frequency domain distance measuring signal and the second frequency domain distance measuring signal; Detection module is used to detect two continuous pairing ranging codes of time domain distance measuring signal; Processing module is used for ranging code is multiplied each other with the corresponding element of the first frequency domain distance measuring signal and the second frequency domain distance measuring signal respectively, obtains first correlated series and second correlated series; First determination module, the corresponding element conjugate multiplication with first correlated series and second correlated series obtains frequency offset; Second determination module with the corresponding adjacent element conjugate multiplication of first correlated series with second correlated series, deducts frequency offset with multiplied result, obtains time offset; Synchronization module is used to utilize time offset to carry out same step calibration.

Wherein, above-mentioned detection module comprises: select module, any one that is used for selecting the first frequency domain distance measuring signal and the second frequency domain distance measuring signal is as reference frequency domain distance measuring signal; First determines submodule, be used for the coherent element of reference frequency domain distance measuring signal respectively with its frequency domain on the conjugation of adjacent backward element multiply each other, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain first with reference to mean value; Second determines submodule, is used for ranging code and corresponding element with reference to the frequency domain distance measuring signal are multiplied each other, and obtains a plurality of values, with each value of obtaining respectively with its conjugate multiplication, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain second with reference to mean value; The 3rd determines submodule, be used for first with reference to mean value divided by second with reference to mean value, obtain with reference to mean value; The 4th determines submodule, is used to utilize the coefficient correlation between the ranging code to obtain the threshold value of finding range; The 5th determines submodule, be used for reference mean value and range finding threshold value are compared, if with reference to mean value greater than the range finding threshold value, then with ranging code as two continuous pairing ranging codes of time domain distance measuring signal.

Wherein, above-mentioned first determination module comprises: continuous item corresponding on first computing module, the conjugation that is used to utilize the first correlated series continuous item and the second correlated series frequency domain multiplies each other, and obtains a plurality of product terms; Second computing module is used for a plurality of product terms are carried out phase adduction calculating mean value, and calculates the multiple angle of mean value, will answer the angle divided by 2 π, obtains frequency offset.

Wherein, above-mentioned second determination module comprises: the 3rd computing module, and be used to utilize continuous item adjacent backward on the conjugation of second correlated series and the first correlated series frequency domain to multiply each other, obtain a plurality of product terms; The 4th computing module is used for a plurality of product terms are carried out phase adduction calculating mean value, and calculates the multiple angle of mean value, will answer the angle divided by 2 π, and the result who obtains is deducted frequency offset, multiply by the fast Fourier transform points N at last and obtains time offset.

By above-mentioned at least one technical scheme of the present invention, utilize two continuous frequency domain distance measuring signals to determine time offset, and considered the influence of frequency offset to time offset, reduced the error of time offset, utilize noise time irrelevance, offset The noise on the carrier wave greatly, improved synchronous precision.

Description of drawings

Accompanying drawing is used to provide further understanding of the present invention, and constitutes the part of specification, is used from explanation the present invention with embodiments of the invention one, is not construed as limiting the invention.In the accompanying drawings:

Fig. 1 is the time-domain description schematic diagram according to the initial ranging transmission of correlation technique;

Fig. 2 is the flow chart according to the synchronous implementation method of the inventive method embodiment;

Fig. 3 is the detailed process flow chart according to the detection ranging code of the inventive method embodiment;

Fig. 4 is the detailed process flow chart according to definite frequency offset of the inventive method embodiment;

Fig. 5 is according to fix time the really detailed process flow chart of side-play amount of the inventive method embodiment;

Fig. 6 is the schematic diagram according to the synchronous implement device of apparatus of the present invention embodiment.

Embodiment

Describe the present invention in detail below in conjunction with accompanying drawing.

Method embodiment

According to the embodiment of the invention, provide a kind of synchronous implementation method.

Fig. 2 is the flow chart according to the synchronous implementation method of the embodiment of the invention, as shown in Figure 2, may further comprise the steps:

Step S202 is converted into the frequency domain distance measuring signal with two continuous time domain distance measuring signals that receive, and obtains the first frequency domain distance measuring signal and the second frequency domain distance measuring signal;

Step S204 detects two continuous pairing ranging codes of time domain distance measuring signal;

Step S206 multiplies each other ranging code respectively with the corresponding element of the first frequency domain distance measuring signal and the second frequency domain distance measuring signal, obtain first correlated series and second correlated series;

Step S208, the corresponding element conjugate multiplication with first correlated series and second correlated series obtains frequency offset;

Step S210 with the corresponding adjacent element conjugate multiplication of first correlated series with second correlated series, deducts frequency offset with multiplied result, obtains time offset;

Step S212 utilizes time offset to carry out same step calibration.

By the technical scheme that the embodiment of the invention provides, eliminated the influence of frequency offset to time offset, reduced the error of time offset, improved synchronous precision.

Wherein, in step S204, the concrete operations that detect two continuous pairing ranging codes of time domain distance measuring signal are: select in the first frequency domain distance measuring signal and the second frequency domain distance measuring signal any one as reference frequency domain distance measuring signal; Will with reference to the coherent element of frequency domain distance measuring signal respectively with its frequency domain on the conjugation of adjacent backward element multiply each other, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain first with reference to mean value; With ranging code with multiply each other with reference to the corresponding element of frequency domain distance measuring signal, obtain a plurality of values, with each value of obtaining respectively with its conjugate multiplication, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain second with reference to mean value; With first with reference to mean value divided by second with reference to mean value, obtain with reference to mean value; Utilize the coefficient correlation between the ranging code to obtain the threshold value of finding range; Will with reference to mean value with the range finding threshold value compare, if with reference to mean value greater than the range finding threshold value, then with ranging code as two continuous pairing ranging codes of time domain distance measuring signal.

Preferably, in step S204, can utilize the above-mentioned first frequency domain distance measuring signal as reference frequency domain distance measuring signal.

Wherein, in step S208, with the corresponding element conjugate multiplication of first correlated series and second correlated series, the operation that obtains frequency offset is specially: continuous item corresponding on the conjugation of utilizing the first correlated series continuous item and the second correlated series frequency domain multiplies each other, and obtains a plurality of product terms; A plurality of product terms are carried out phase adduction calculating mean value, and calculate the multiple angle of mean value, will answer the angle, obtain frequency offset divided by 2 π.

Wherein, in step S210, with the corresponding adjacent element conjugate multiplication of first correlated series with second correlated series, multiplied result is deducted frequency offset, the operation that obtains time offset is specially: utilize continuous item adjacent backward on the conjugation of the second correlated series continuous item and the first correlated series frequency domain to multiply each other, obtain a plurality of product terms; A plurality of product terms are carried out phase adduction calculating mean value, and calculate the multiple angle of mean value, will answer the angle, the result who obtains is deducted frequency offset, multiply by the fast Fourier transform points N at last and obtain time offset divided by 2 π.

Fig. 3 is the ranging code testing process figure of the side embodiment according to the present invention, as shown in Figure 3, may further comprise the steps:

Step S302 arrives frequency domain with two continued time domain distance measuring signals that receive by N point quick Fourier conversion conversion (FFT);

The time domain of supposing n sampled point of the individual time domain distance measuring signal of i (i=0,1) that the user sends is output as:

$y_n^i=\frac{1}{N}\underset{k=0}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}(i\·N+n)/N}+w_n^i$

Wherein, X _kBe the data on the frequency domain carrier wave, go up X in the position of range finding carrier wave (position of range finding carrier wave is stipulated by agreement) _k=1 or-1, X on other positions _kBe all 0, H _k ⁱIt is the channel response on k the carrier wave of the individual time domain distance measuring signal of i (i=0,1); ε is a frequency offset, and unit is the carrier wave basic interval; N represents useful symbol time, and unit is a sampled point; Because the protection interval of the second range finding symbol is at the afterbody of symbol, so differ N sampled point, w on two range finding symbol times _n ⁱIt is white Gaussian noise;

With having of receiving the signal of time delay make FFT, time-domain signal is changed to result's being expressed as on l carrier wave of frequency domain:

$Y_l^i=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{y}_n^i\·e^{-j2\mathrm{\πl}\·n/N}{e}^{-j2\mathrm{\π}\frac{l\·\mathrm{\τ}}{N}}$

$=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}(\frac{1}{N}\underset{k=0}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}(i\·N+n)/N}+w_n)\·e^{-j2\mathrm{\πl}\·n/N}\·e^{-j2\mathrm{\πl}\·\mathrm{\τ}/N}$

$=X_l{H}_l^i\frac{\sin (\mathrm{\π\ϵ}\·(i\·N+1))}{N\×\sin (\mathrm{\π\ϵ}\·(i\·N+1)/N)}{e}^{\mathrm{j\π\ϵ}\·(i\·N+1)(N-1)/N}\·e^{-j2\mathrm{\π}\·\mathrm{\τ}\·l/N}+{\mathrm{ICI}}_l^i+W_l^i$

Wherein, Y _l ⁱBe the frequency domain distance measuring signal, when i=0, Y _l ⁰Be the first frequency domain distance measuring signal mentioned above, when i=1, Y _l ¹Be the second frequency domain distance measuring signal mentioned above, τ is a time offset in the formula, is unit with the sampling point, W _l ⁱBe the frequency domain representation of white noise, ICI _l ⁱBe interchannel interference, determine by following formula from other carrier waves:

$Y_l^0=X_l{H}_l^0\frac{\sin \left(\mathrm{\π\ϵ}\right)}{N\×\sin (\mathrm{\π\ϵ}/N)}{e}^{\mathrm{j\π\ϵ}\·(N-1)/N}\·e^{-j2\mathrm{\π}\·\mathrm{\τ}\·l/N}+W_l^0$

In fact, | ICI _l ⁱ| can estimate, we did analysis and test to the interference level that the different frequency side-play amount causes, at frequency offset during less than 0.1 carrier spacing, $\left|{\mathrm{ICI}}_l^0\right|\≈0,$ Can ignore, but because frequency offset is characterized by the rotation of phase place on time domain, and add up in time, so the amount of phase rotation of second symbol is N ε, at this moment | ICI _l ¹| can not ignore, only use first range finding symbol, thus, obtain so ranging code detects

$Y_l^0=X_l{H}_l^0\frac{\sin \left(\mathrm{\π\ϵ}\right)}{N\×\sin (\mathrm{\π\ϵ}/N)}{e}^{\mathrm{j\π\ϵ}\·(N-1)/N}\·e^{-j2\mathrm{\π}\·\mathrm{\τ}\·l/N}+W_l^0;$

Step S304 selects all ranging sub-carrier signals on frequency domain, renumber group by the order from small to large of sub-carrier indices and grow into 144 sequence and will be labeled as Y ₁ ⁱ, Y ₂ ⁱY _t ⁱY ₁₄₄ ⁱ

Step S306, the range finding carrier wave sequence that obtains among ranging code C of selection from the ranging code set of backstage, base station configuration and the S304 is made corresponding carrier wave element and is multiplied each other, and obtains correlated series Z ⁱ, promptly

$Z^i=(Z_1^i,Z_2^i,\·\·\·\·\·\·Z_l^i\·\·\·\·\·\·Z_{144}^i)$

$Z_l^i=Y_l^i\·C_l$

Notice Z _l ⁱSubscript and Y _l ⁱThe subscript correspondence, and Y _l ⁱSubscript be associated so Z with sub-carrier indices _l ⁱAlso be associated with sub-carrier indices;

Step S308 is the corresponding " Z of adjacent sub-carrier index in the carrier wave of first symbol patch block same with it (tile) (annotate: the allocation of carriers mode in the present embodiment is according to the part sub-carrier distribution manner of stipulating in the 802.16e agreement) _l ⁰Right " conjugate multiplication, promptly carry out following computing

$Z_l^0{\left(Z_{l+1}^0\right)}^{*}=X_l{C}_l{X}_{l+1}{C}_{l+1}{H}_l^0{\left(H_{l+1}^0\right)}^{*}\frac{{\sin }^2\mathrm{\π\ϵ}}{N^2\×{\sin }^2(\mathrm{\π\ϵ}/N)}\·e^{j2\mathrm{\π}\·\mathrm{\τ}/N}+W_l^0{C}_l{W}_{l+1}^0{C}_{l+1}$

$+X_l{C}_l{e}^{-j2\mathrm{\π}\·\mathrm{\τ}\·l/N}{\left(W_{l+1}^0\right)}^{*}{C}_{l+1}+W_l^0{C}_l{X}_{l+1}{C}_{l+1}{e}^{j2\mathrm{\π}\·l\·\mathrm{\τ}+1/N}$

By stipulating in the agreement that up carrier wave is the tile framework, 4 continuous carrier waves are arranged, in each tile so 3 " Z are arranged in each tile _l ⁰Right ", and range channel is made up of 36 tile, so have 108 " Z _l ⁰Right ";

Step S310 is with 108 " Z that obtain among the step S308 _l ⁰Right " all of sequence add up, and ask its mean value, promptly

$Q=\frac{1}{108}\underset{N_{\mathrm{tile}}=0}{\overset{35}{\mathrm{\Σ}}}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{Z}_{N_{\mathrm{tile}}\·4+i+1}^0\·{\left(Z_{N_{\mathrm{tile}}\·4+i+1}^0\right)}^{*};$

Q is mentioned above first with reference to mean value;

Step S312 is the correlated series Z of first symbol ⁰With himself conjugate multiplication, and ask it average after all product terms are added up, promptly

$S=\frac{1}{144}\underset{l=1}{\overset{144}{\mathrm{\Σ}}}{Z}_l^0\·{\left(Z_l^0\right)}^{*};$

S is mentioned above second with reference to mean value;

Step S314 obtains ratio η with the real part of the mean value among the step S310 divided by the mean value among the step S312, promptly

$\mathrm{\η}=\frac{\mathrm{real}\left(Q\right)}{S};$

η is a reference mean value mentioned above;

Step S316, according to correlation between the ranging code and simulation result, the threshold value ρ that obtains finding range, wherein the value of ρ can be 0.25;

Step S318 compares ratio η among the step S314 and the threshold value ρ among the step S316, if η＞ρ, then this ranging code C is the ranging code that the user sends, execution in step S320 then, otherwise, repeating step S306-step S318;

Step S320 preserves correlated series Z ⁱWith ranging code C.

Above-mentioned implementation step has provided the method that detects ranging code, has considered frequency offset to synchronous influence, and the ratio by twice mean value detects ranging code, has improved synchronization accuracy.

Fig. 4 is the flow chart according to definite frequency offset of the embodiment of the invention, as shown in Figure 4, may further comprise the steps:

Step S402 is with the corresponding carrier wave conjugate multiplication of two correlated serieses of preserving among the above-mentioned steps S320, promptly

Wherein, Z _l ⁰Be first correlated series mentioned above, Z _l ¹It is second correlated series mentioned above;

Get by Digital Signal Processing knowledge

$Z_l^i=Y_l^i\·C_l$

$=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}(\frac{1}{N}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}(i\·N+n)/N}+w_n)\·e^{-j2\mathrm{\πl}\·n/N}\·e^{-j2\mathrm{\πl}\·\mathrm{\τ}/N}\·C_l$

$=\frac{1}{N}\·C_l\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}(i\·N+n)/N}{e}^{-j2\mathrm{\πl}\·n/N}{e}^{-2\mathrm{\πl}\·\mathrm{\τ}/N}+W_l^i$

$=\frac{1}{N}\·C_l\·e^{j2\mathrm{\π\ϵ}\·i}\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}{e}^{-2\mathrm{\πl}\·\mathrm{\τ}/N}+W_l^i$

Because distance measuring signal sends identical ranging code, and continuous in time, so can think channel response H on two corresponding carrier waves of range finding symbol _k ⁱIdentical, do not consider noise, Z for the time being _l ⁰And Z _l ¹Just differ e ^{J2 π ε}So,

$F_l={\left(Z_l^0\right)}^{*}\·Z_l^1=e^{j2\mathrm{\π\ϵ}}{\left|\right|\frac{1}{N}\·C_l\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}{e}^{-j2\mathrm{\πl}\·\mathrm{\τ}/N}\left|\right|}^2+W_l;$

Step S404, the sequence that step S402 is obtained adds up, and asks its mean value E, wherein,

$E=\underset{l=1}{\overset{144}{\mathrm{\Σ}}}{F}_l=\underset{l=1}{\overset{144}{\mathrm{\Σ}}}(e^{j2\mathrm{\π\ϵ}}{\left|\right|\frac{1}{N}\·C_l\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}{e}^{-j2\mathrm{\πl}\·\mathrm{\τ}/N}\left|\right|}^2+W_l)$

Because white Gaussian noise is obeyed independent Gaussian Profile, so $\underset{l=1}{\overset{144}{\mathrm{\Σ}}}{W}_l\≈0,$ So

$E\≈e^{j2\mathrm{\π\ϵ}}\·\underset{l=1}{\overset{144}{\mathrm{\Σ}}}{\left|\right|\frac{1}{N}\·C_l\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}{e}^{-j2\mathrm{\πl}\·\mathrm{\τ}/N}\left|\right|}^2$

So the multiple angle of E is exactly 2 π ε, obtain user's frequency offset according to this;

Step S406 makes arctangent cp cp operation to the average among the step S404, obtains its multiple angle;

Step S408 divided by 2 π, obtains user's frequency offset ε with the multiple angle among the step S406.

Above-mentioned implementation step has provided the method for definite frequency offset, and wherein, the frequency offset ε that determines is through normalized value, and the carrier number of expression frequency shift (FS) by this method, can improve synchronous precision.

Fig. 5 is according to fix time the really flow chart of side-play amount of the embodiment of the invention, as shown in Figure 5, may further comprise the steps:

Step S502 is with two correlated series adjacent carrier conjugate multiplication of preserving among the step S320, promptly

T＝(T ₁，T ₂…T _l…T ₁₀₈)

$T_l={\left(Z_{N_{\mathrm{tile}}\·4+i}^1\right)}^{*}\·Z_{N_{\mathrm{tile}}\·4+i+1}^0$

$Z_l^i=Y_l^i\·C_l$

$=\frac{1}{N}\·C_l\·e^{j2\mathrm{\π\ϵ}\·i}{e}^{-j2\mathrm{\πl}\·\mathrm{\τ}/N}\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}+W_l^i$

Ignore noise for the time being, and the channel of adjacent-symbol adjacent carrier is corresponding identical, can be found by following formula, adjacent carrier distinct symbols Z _L+1 ⁰And Z _l ¹Just differ e ^{J2 π (ε+τ/N)}, promptly

$T_l=e^{j2\mathrm{\π}(\mathrm{\ϵ}+\mathrm{\τ}/N)}{\left|\right|\frac{1}{N}\·C_l\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}\left|\right|}^2+W_l;$

Step S504 adds up the sequence that obtains among the step S502, and asks its mean value G, wherein,

$G=\frac{1}{108}\underset{N_{\mathrm{tile}}=0}{\overset{35}{\mathrm{\Σ}}}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{T}_{N_{\mathrm{tile}}\·4+i}=\frac{1}{108}\underset{N_{\mathrm{tile}}=0}{\overset{35}{\mathrm{\Σ}}}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{Z}_{N_{\mathrm{tile}}\·4+i}^1\·(Z_{N_{\mathrm{tile}}\·4+i+1}^0{)}^{*}$

$=e^{j2\mathrm{\π}(\mathrm{\ϵ}+\mathrm{\τ}/N)}\·\frac{1}{108}\underset{l=1}{\overset{108}{\mathrm{\Σ}}}{(\left|\right|\frac{1}{N}\·C_l\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}\left|\right|}^2+W_l)$

Because white Gaussian noise is obeyed independent Gaussian Profile, so $\underset{l=1}{\overset{108}{\mathrm{\Σ}}}{W}_l\≈0,$ So

${G\≈e}^{j2\mathrm{\π}(\mathrm{\ϵ}+\mathrm{\τ}/N)}\·\frac{1}{108}\underset{l=1}{\overset{108}{\mathrm{\Σ}}}{\left|\right|\frac{1}{N}\·C_l\·\underset{k=1}{\overset{N}{\mathrm{\Σ}}}{X}_k{H}_k^i\·\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{e}^{2\mathrm{\πjnk}/N}{e}^{j2\mathrm{\π\ϵ}\·n/N}{e}^{-j2\mathrm{\πl}\·n/N}\left|\right|}^2$

So the multiple angle of G is exactly 2 π (ε+τ/N), can obtain user's time offset according to this;

Step S506 makes arctangent cp cp operation to the mean value among the step S504, obtains its multiple angle;

Step S508 deducts user's frequency offset ε after divided by 2 π with the multiple angle that obtains among the step S506, utilizes the result who obtains to multiply by the sampling number N of symbol, obtains user's time offset τ.

Above-mentioned implementation step has provided the method for definite time offset, wherein, the time offset τ that determines is through normalized value, the sampled point number of expression skew, as can be seen, the present invention at first determines frequency offset, carries out determining time offset again behind the compensate of frequency deviation, eliminated the influence of frequency shift (FS) to time migration

Device embodiment

Fig. 6 shows the synchronous implement device schematic diagram according to the embodiment of the invention, and this device comprises:

Modular converter 10, two continuous time domain distance measuring signals that are used for receiving are converted into the frequency domain distance measuring signal, obtain the first frequency domain distance measuring signal and the second frequency domain distance measuring signal;

Detection module 20 is used to detect two continuous pairing ranging codes of time domain distance measuring signal, and this module can be connected to modular converter 10;

Processing module 30 is used for ranging code is multiplied each other with the corresponding element of the first frequency domain distance measuring signal and the second frequency domain distance measuring signal respectively, obtains first correlated series and second correlated series, and this module can be connected to modular converter 10 and detection module 20;

First determination module 40 is used for the corresponding element conjugate multiplication with first correlated series and second correlated series, obtains frequency offset, and this module can be connected to processing module 30;

Second determination module 50 is used for the corresponding adjacent element conjugate multiplication of first correlated series with second correlated series deducted frequency offset with multiplied result, obtains time offset, and this module can be connected to processing module 30;

Synchronization module 60 is used to utilize time offset to carry out same step calibration, and this module can be connected to second determination module 50.

Wherein, detection module 20 comprises: select module, any one that is used for selecting the first frequency domain distance measuring signal and the second frequency domain distance measuring signal is as reference frequency domain distance measuring signal; First determines submodule, be used for the coherent element of reference frequency domain distance measuring signal respectively with its frequency domain on the conjugation of adjacent backward element multiply each other, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain first with reference to mean value; Second determines submodule, is used for ranging code and corresponding element with reference to the frequency domain distance measuring signal are multiplied each other, and obtains a plurality of values, with each value of obtaining respectively with its conjugate multiplication, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain second with reference to mean value; The 3rd determines submodule, be used for first with reference to mean value divided by second with reference to mean value, obtain with reference to mean value; The 4th determines submodule, is used to utilize the coefficient correlation between the ranging code to obtain the threshold value of finding range; The 5th determines submodule, be used for reference mean value and range finding threshold value are compared, if with reference to mean value greater than the range finding threshold value, then with ranging code as two continuous pairing ranging codes of time domain distance measuring signal.

Wherein, first determination module 40 comprises: continuous item corresponding on first computing module, the conjugation that is used to utilize the first correlated series continuous item and the second correlated series frequency domain multiplies each other, and obtains a plurality of product terms; Second computing module is used for a plurality of product terms are carried out phase adduction calculating mean value, and calculates the multiple angle of mean value, will answer the angle divided by 2 π, obtains frequency offset.

Wherein, second determination module 50 comprises: the 3rd computing module, and be used to utilize continuous item adjacent backward on the conjugation of second correlated series and the first correlated series frequency domain to multiply each other, obtain a plurality of product terms; The 4th computing module is used for a plurality of product terms are carried out phase adduction calculating mean value, and calculates the multiple angle of mean value, will answer the angle divided by 2 π, and the result who obtains is deducted frequency offset, multiply by the fast Fourier transform points N at last and obtains time offset.

The synchronous implement device that provides by the embodiment of the invention, utilize two continuous frequency domain distance measuring signals to determine time offset, and considered the influence of frequency offset to time offset, reduced the error of time offset, utilize noise time irrelevance, offset The noise on the carrier wave greatly, improved synchronous precision.

As above, by means of synchronous implementation method provided by the invention and/or device, propose a kind of simple, reliable more mode and come the time offset of estimating user, utilize two continuous frequency domain distance measuring signals to determine time offset, and considered the influence of frequency offset, reduced the error of time offset, utilized noise time irrelevance time offset, offset The noise on the carrier wave greatly, improved synchronous precision; And can utilize existing hardware arithmetic element, realize simply having reduced the chip area of final realization; For the WMAN system, the up initial access symbol timing synchronization method that is proposed utilizes the existing fast Fourier transform (FFT) hardware of receiving terminal to realize, need not be against fast fourier transform (IFFT) hardware, so realized reducing the purpose of hardware complexity; For the initial access user who has big frequency offset, especially to the user of access under the fast state, improved the precision of its sign synchronization greatly, shortened the time that the user inserts to a certain extent, reduced the cutting off rate in the subscriber handover process.

The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. a synchronous implementation method is characterized in that, comprising:

Two continuous time domain distance measuring signals that receive are converted into the frequency domain distance measuring signal, obtain the first frequency domain distance measuring signal and the second frequency domain distance measuring signal;

Detect described two continuous pairing ranging codes of time domain distance measuring signal;

Described ranging code is multiplied each other with the corresponding element of described first frequency domain distance measuring signal and the described second frequency domain distance measuring signal respectively, obtain first correlated series and second correlated series;

Corresponding element conjugate multiplication with described first correlated series and described second correlated series obtains frequency offset;

With the corresponding adjacent element conjugate multiplication of described first correlated series with described second correlated series, multiplied result is deducted described frequency offset, obtain time offset;

Utilize described time offset to carry out same step calibration.

2. method according to claim 1 is characterized in that, the concrete operations that detect described two continuous pairing ranging codes of time domain distance measuring signal are:

Select in described first frequency domain distance measuring signal and the described second frequency domain distance measuring signal any one as reference frequency domain distance measuring signal;

With described coherent element with reference to the frequency domain distance measuring signal respectively with its frequency domain on the conjugation of adjacent backward element multiply each other, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain first with reference to mean value;

Described ranging code and described corresponding element with reference to the frequency domain distance measuring signal are multiplied each other, obtain a plurality of values, with each value of obtaining respectively with its conjugate multiplication, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain second with reference to mean value;

With described first with reference to mean value divided by described second with reference to mean value, obtain with reference to mean value;

Utilize the coefficient correlation between the described ranging code to obtain the threshold value of finding range;

Compare with reference to mean value and described range finding threshold value described, if described with reference to mean value greater than described range finding threshold value, then with described ranging code as described two continuous pairing ranging codes of time domain distance measuring signal.

3. method according to claim 2 is characterized in that, utilize the described first frequency domain distance measuring signal as described with reference to the frequency domain distance measuring signal.

4. method according to claim 1 is characterized in that, with the corresponding element conjugate multiplication of described first correlated series and described second correlated series, the operation that obtains frequency offset is specially:

Continuous item corresponding on the conjugation of utilizing the described first correlated series continuous item and the second correlated series frequency domain multiplies each other, and obtains a plurality of product terms;

Described a plurality of product terms are carried out phase adduction calculating mean value, and calculate the multiple angle of described mean value, described multiple angle divided by 2 π, is obtained described frequency offset.

5. method according to claim 1 is characterized in that, described the corresponding adjacent element conjugate multiplication of first correlated series with second correlated series is deducted frequency offset with multiplied result, and the operation that obtains time offset is specially:

Utilize continuous item adjacent backward on the conjugation of the described second correlated series continuous item and the described first correlated series frequency domain to multiply each other, obtain a plurality of product terms;

Described a plurality of product terms are carried out phase adduction calculating mean value, and calculate the multiple angle of described mean value, described multiple angle divided by 2 π, is deducted described frequency offset with the result who obtains, multiply by the fast fourier transform points N and obtain described time offset.

6. a synchronous implement device is characterized in that, comprising:

Modular converter, two continuous time domain distance measuring signals that are used for receiving are converted into the frequency domain distance measuring signal, obtain the first frequency domain distance measuring signal and the second frequency domain distance measuring signal;

Detection module is used to detect described two continuous pairing ranging codes of time domain distance measuring signal;

Processing module is used for described ranging code is multiplied each other with the corresponding element of described first frequency domain distance measuring signal and the described second frequency domain distance measuring signal respectively, obtains first correlated series and second correlated series;

First determination module, the corresponding element conjugate multiplication with described first correlated series and described second correlated series obtains frequency offset;

Second determination module with the corresponding adjacent element conjugate multiplication of described first correlated series with described second correlated series, deducts described frequency offset with multiplied result, obtains time offset;

Synchronization module is used to utilize described time offset to carry out same step calibration.

7. device according to claim 6 is characterized in that, described detection module comprises:

Select module, any one that is used for selecting described first frequency domain distance measuring signal and the described second frequency domain distance measuring signal is as reference frequency domain distance measuring signal;

First determines submodule, be used for described coherent element with reference to the frequency domain distance measuring signal respectively with its frequency domain on the conjugation of adjacent backward element multiply each other, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain first with reference to mean value;

Second determines submodule, is used for described ranging code and described corresponding element with reference to the frequency domain distance measuring signal are multiplied each other, and obtains a plurality of values, with each value of obtaining respectively with its conjugate multiplication, obtain a plurality of product terms, all product terms are carried out phase adduction calculating mean value, obtain second with reference to mean value;

The 3rd determines submodule, be used for described first with reference to mean value divided by described second with reference to mean value, obtain with reference to mean value;

The 4th determines submodule, is used to utilize the coefficient correlation between the described ranging code to obtain the threshold value of finding range;

The 5th determines to be used for submodule comparing with reference to mean value and described range finding threshold value described, if described with reference to mean value greater than described range finding threshold value, then with described ranging code as described two continuous pairing ranging codes of time domain distance measuring signal.

8. according to claim 6 or 7 described devices, it is characterized in that described first determination module comprises:

Continuous item corresponding on first computing module, the conjugation that is used to utilize the described first correlated series continuous item and the second correlated series frequency domain multiplies each other, and obtains a plurality of product terms;

Second computing module is used for described a plurality of product terms are carried out phase adduction calculating mean value, and calculates the multiple angle of described mean value, and described multiple angle divided by 2 π, is obtained described frequency offset.

9. according to claim 6 or 7 described devices, it is characterized in that described second determination module comprises:

The 3rd computing module is used to utilize continuous item adjacent backward on the conjugation of second correlated series and the first correlated series frequency domain to multiply each other, and obtains a plurality of product terms;

The 4th computing module is used for a plurality of product terms are carried out phase adduction calculating mean value, and calculates the multiple angle of mean value, will answer the angle divided by 2 π, and the result who obtains is deducted frequency offset, multiply by the fast Fourier transform points N at last and obtains time offset.

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