CN101814931A - Doppler frequency shift estimation and compensation method in TD-SCDMA (Time Division-Synchronization Code Division Multiple Access) system - Google Patents

Abstract

The invention relates to a Doppler frequency shift estimation and compensation method in a TD-SCDMA (Time Division-Synchronization Code Division Multiple Access) system. The method comprises the following step of: after a mobile terminal receives a time slot containing the data of the mobile terminal, obtaining a Doppler frequency offset value of a receiving signal of the current time slot through comparing the phase differences of channel estimation sequences of the current time slot and a comparison time slot. The compensation method of the Doppler frequency shift in the TD-SCDMA system comprises the following steps of: after the mobile terminal receives the time slot containing the data of the mobile terminal, obtaining the Doppler frequency offset value of the receiving signal of the current time slot through comparing the phase differences of the channel estimation sequences of the current time slot and the comparison time slot; and correcting the receiving signal in joint detection by combining with the joint combination. The invention improves the accuracy of channel estimation, eliminates the influences of the Doppler frequency shift on correctly receiving demodulation, reduces the error rate and improves the system performance and is particularly suitable for TD-SCDMA terminals under high-speed motion scenes.

Description

The method that Doppler frequency shift is estimated and compensated in the TD-SCDMA system

Technical field

The present invention relates to mobile communication technology, relate in particular to a kind of Doppler frequency shift estimation and compensation method in TD SDMA (TD-SCDMA) system.

Background technology

TD-SCDMA (TD SDMA) mobile communication system is a kind of 3-G (Generation Three mobile communication system) based on time division duplex, code division multiple access, has characteristics such as uplink-downlink configuration is flexible, code check is low, availability of frequency spectrum height.

As shown in Figure 1, in the TD-SCDMA system, the base unit of transmission data is radio frames.(TS0～TS6) form a subframe with 3 special time slots (descending synchronous code section DwPTS, protection be GP and uplink synchronous code section UpPTS at interval), two subframes (subframe #1 and subframe #2) constitute the radio frames that duration is 10ms to 7 conventional time slots.The data of mobile phone users are placed in the conventional time slot to be transmitted, and a conventional time slot duration is 675 μ s, is made of 864 chips (chip), and each chip duration is 0.78125 μ s.These chips are divided into four parts: i.e. the protection of two data segments (each 352 chip), a midamble code section (midamble) (144 chips) and one 16 chip lengths is GP at interval; Each data segment is made of through spread spectrum, scrambling, aliasing the data of a plurality of portable terminal code channels that will transmit; Constitute after the basic midamble sign indicating number displacement of midamble code section by system assignment, its effect is to use when being used as training sequence for channel estimating.

According to present TD-SCDMA technology, it supports that the maximum translational speed of portable terminal is 120km/h.Yet in actual life, speed per hour occurred up to the bullet train more than 250 kilometers, and the high ferro net of higher speed per hour 300km/h～500km/h can spread all over the country in the near future, this has just proposed very big challenge to existing TD wireless technology.When portable terminal is in high-speed motion state, the Doppler frequency shift that wireless signal suffered of space transmission can become very serious, and along with the rising of carrier frequency, Doppler frequency shift increases, Doppler frequency shift and carrier frequency and portable terminal speed are proportional, that is:

$f_d=f_{\mathrm{RF}}\×\frac{v}{c}\×\cos \mathrm{\θ}$

Wherein, f _dExpression Doppler frequency deviation value, f _RFThe expression carrier frequency, v represents the speed of motion of mobile terminals, c represents the light velocity, equals 3*10 ⁸M/s, θ represent that motion of mobile terminals direction and radio wave incide the angle between portable terminal.At mobile terminal side, doppler shift effect make local demodulation carrier wave and portable terminal actual reception to the frequency of signal between produced deviation, and the deviation on this frequency has just caused the modulation symbol of demodulation symbol and standard deflection (distortion) to occur on phase place after accumulating in time.Especially for the TD system, because it is a low code check system, the duration of each chip is longer, so that the demodulation symbol phase distortion of accumulating on each chip also just becomes is bigger, this will influence correct reception, the demodulation of portable terminal widely.

On the other hand, the portable terminal of TD-SCDMA has generally adopted associated detection technique when doing receiving demodulation.Joint-detection utilizes the prior information in the multiple access interference to regard the separation of all portable terminal signals as a unified process, the chip signal that the aliasing that receives converts the demodulation symbol of each portable terminal to with settling at one go, thereby reduced the mutual interference of multi-mobile-terminal, increased power system capacity.Yet the validity of associated detection technique is based upon accurately on the channel estimating basis, and the realization of existing TD channel estimating has adopted the low-cost fast Fourier transform FFT/ inverse fast Fourier transform IFFT based on Steiner to add that follow-up detection threshold removes the method for noise tap.This technology is at Steiner B.BAIEP. " Low cost channel estimation in the uplink receiver of CDMAmobile radio systems " Frequenz 1993,47 (12): 292-298 and " improvement of low-cost channel estimation methods in the TD-SCDMA system " journals of communicating by letter such as Kang Shaoli, the 23rd volume, there was detailed explanation the 10th phase 125～130.This channel estimation technique is based on time slot, thinks that promptly channel is changeless in a slot time; But in fact the decline the time experienced in motion of portable terminal has been subjected to the modulation of Doppler frequency shift, that is to say when in fact channel is to become that actual with the estimated channel value that goes out of existing method of estimation is channel mean in a slot time section in a time slot.Therefore, the estimation channel that adopts this method of estimation to obtain just and between the real channel exists error, especially portable terminal is under the state of high-speed motion, error is very big, if will have the estimation channel of error again is brought in the joint-detection matrix, will cause repeating stack and amplifying of interference, thereby influence being correctly decoded of data.

Summary of the invention

The technical problem to be solved in the present invention provides in a kind of TD-SCDMA system to be estimated and compensation method Doppler frequency shift, to overcome since portable terminal move the adverse effect that correct reception data are brought.

For addressing the above problem, the invention provides the method for estimation of Doppler frequency deviation value in a kind of TD SDMA TD-SCDMA system, comprising:

Portable terminal is after receiving the time slot that contains this mobile terminal data, by comparing the Doppler frequency deviation value that a current time slots and a phase difference that compares the channel estimation sequence of time slot obtain the current time slots received signal.

Further, said method also can have following feature:

Preserve interval the reaching and the interval corresponding comparison time slot of each scope of scope of the absolute value of predefined n Doppler frequency deviation value on the described portable terminal, wherein, this n scope interval contained the absolute value of all possible Doppler frequency deviation value, n 〉=1 piecemeal;

Described portable terminal is meant by the received signal Doppler frequency deviation value that comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot obtain this portable terminal:

The absolute value of the anticipation value of the Doppler frequency deviation value of judgement current time slots is positioned at above-mentioned which scope interval;

By the interval definite corresponding relatively time slot of the described scope of judging;

By relatively current time slots and the phase difference estimation of described relatively time slot on the correspondence footpath go out the phase pushing figure of received signal on the every chip lengths of this time slot that is caused by Doppler frequency shift.

Further, said method also can have following feature:

The anticipation value of the Doppler frequency deviation value of described current time slots is the Doppler frequency deviation value of a processing time slot on this portable terminal;

A Doppler frequency deviation value of handling time slot is meant on described this portable terminal: the Doppler frequency deviation value on the estimated most powerful path of this portable terminal at this time slot that obtains when containing the time slot of this mobile terminal data, perhaps this portable terminal maximum Doppler frequency deviation value or above-mentioned two weighted sum in each footpath of this time slot on handling of preserving in this portable terminal.

Further, said method also can have following feature:

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

Intercept the described relatively training sequence of time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot;

The training sequence of intercepting current time slots is done channel estimating, estimates the average channel impulse response of each portable terminal in current time slots;

Described current time slots is subtracted each other by the corresponding phase place of directly carrying out with this portable terminal part of the relatively average channel impulse response of time slot, divided by the chip-spaced length between above-mentioned two time slots, obtain the phase of received signal side-play amount of this portable terminal on every footpath, every chip that Doppler frequency shift causes again.

Further, said method also can have following feature:

When n=2, described scope interval comprises: A=[0, X), B=[X, + ∞), the pairing relatively time slot of the interval A of described scope is the time slot that has identical timeslot number in the last subframe with current time slots, the pairing relatively time slot of described scope interval B is the TS0 time slot in the subframe of current time slots place, wherein, the value of X is determined according to engineering is actual.

Further, said method also can have following feature:

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

When time slot relatively is TS0 time slot in this frame, intercept the training sequence of described TS0 time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot; When described relatively time slot is when being in time slot with time slot with current time slots in the previous frame, obtain the described relatively average channel impulse response of time slot according to the keeping records of described portable terminal;

The training sequence of intercepting current time slots is done channel estimating, estimates each portable terminal in the average channel impulse response of current time slots in the period;

Described portable terminal carries out phase place with the channel estimation value of most powerful path in current time slots and the described relatively time slot and subtracts each other, divided by current time slots and the described relatively chip-spaced length of time slot, obtain the phase of received signal side-play amount of this portable terminal on every chip that Doppler frequency shift causes again.

The present invention also provides the compensation method of Doppler frequency shift in a kind of TD SDMA TD-SCDMA system, comprising:

Portable terminal is after receiving the time slot that contains this mobile terminal data, by comparing the Doppler frequency deviation value that a current time slots and a phase difference that compares the channel estimation sequence of time slot obtain the current time slots received signal, and, in joint-detection, described received signal is revised in conjunction with joint-detection.

Further, said method also can have following feature:

Preserve interval the reaching and the interval corresponding comparison time slot of each scope of scope of the absolute value of predefined n Doppler frequency deviation value on the described portable terminal, wherein, this n scope interval contained the absolute value of all possible Doppler frequency deviation value, n 〉=1 piecemeal;

Described portable terminal is meant by the received signal Doppler frequency deviation value that comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot obtain this portable terminal:

The absolute value of the anticipation value of the Doppler frequency deviation value of judgement current time slots is positioned at above-mentioned which scope interval;

By the interval definite corresponding relatively time slot of the described scope of judging;

By relatively current time slots and the phase difference estimation of described relatively time slot on the correspondence footpath go out the phase pushing figure of received signal on the every chip lengths of this time slot that is caused by Doppler frequency shift.

Further, said method also can have following feature:

The anticipation value of the Doppler frequency deviation value of described current time slots is the Doppler frequency deviation value of a processing time slot on this portable terminal;

A Doppler frequency deviation value of handling time slot is meant on described this portable terminal: the Doppler frequency deviation value on the estimated most powerful path of this portable terminal at this time slot that obtains when containing the time slot of this mobile terminal data, perhaps this portable terminal maximum Doppler frequency deviation value or above-mentioned two weighted sum in each footpath of this time slot on handling of preserving in this portable terminal.

Further, said method also can have following feature:

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

Intercept the described relatively training sequence of time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot;

The training sequence of intercepting current time slots is done channel estimating, estimates the average channel impulse response of each portable terminal in current time slots;

Described current time slots is subtracted each other by the corresponding phase place of directly carrying out with this portable terminal part of the relatively average channel impulse response of time slot, divided by the chip-spaced length between above-mentioned two time slots, obtain the phase of received signal side-play amount of this portable terminal on every footpath, every chip that Doppler frequency shift causes again.

Further, said method also can have following feature:

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

When time slot relatively is TS0 time slot in this frame, intercept the training sequence of described TS0 time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot; When described relatively time slot is when being in time slot with time slot with current time slots in the previous frame, obtain the described relatively average channel impulse response of time slot according to the keeping records of described portable terminal;

The training sequence of intercepting current time slots is done channel estimating, estimates each portable terminal in the average channel impulse response of current time slots in the period;

Described portable terminal carries out phase place with the channel estimation value of most powerful path in current time slots and the described relatively time slot and subtracts each other, divided by current time slots and the described relatively chip-spaced length of time slot, obtain the phase of received signal side-play amount of this portable terminal on every chip that Doppler frequency shift causes again.

Further, said method also can have following feature:

Described received signal to each portable terminal is revised specifically in joint-detection to be comprised:

The described phase pushing figure that obtains be multiply by behind the spreading factor SF compensate described each portable terminal in the average channel impulse response of current time slots in the period by the footpath;

Multiply each other by spreading code, channel code, the scrambler of each portable terminal and to obtain the compound spreading code of each portable terminal respectively;

Utilize the average channel impulse response after the described compensation and the compound spreading code tectonic syntaxis of described each portable terminal to detect matrix A, and the data segment in the current time slots is carried out joint-detection, obtain revised demodulation symbol with described joint-detection matrix A.

Further, said method also can comprise:

Do the phase bit comparison with the described demodulation symbol that obtains with standard modulation symbols in the planisphere, the gained phase difference is made smoothing processing to the phase place frequency deviation value and/or the maximum phase place frequency deviation value of the most powerful path of each portable terminal, and the result after handling is preserved as the Doppler frequency deviation value of this time slot.

Compared with prior art, the present invention has improved accuracy of channel estimation, has eliminated the influence of Doppler frequency shift to correct receiving demodulation, has reduced the error rate, thereby improved systematic function, and be particularly useful for the scene of TD-SCDMA portable terminal under high-speed motion.Reconcile the precision of estimating Doppler frequency deviation by selecting suitable comparison time slot, and come the estimating Doppler frequency deviation by the computing of relatively time slot and current time slots being carried out phase difference, and in the preferred case, the phase deviation that portable terminal only carries out the received signal that Doppler frequency shift caused to most powerful path (main footpath) is estimated and compensate, reduced the complexity of method enforcement; In addition, portable terminal can also compare the next further reduction method complexity of channel estimation sequence and the overhead of time slot by storage.

Description of drawings

Fig. 1 is the frame structure schematic diagram of TD-SCDMA in the prior art;

Fig. 2 is subjected to Doppler frequency shift to modulate the schematic diagram of the phase deviation that is caused in a conventional time slot section for each footpath of wireless channel in the embodiment of the invention;

Fig. 3 is the flow chart of method in the embodiment of the invention;

Fig. 4 is the channel window schematic diagram of Steiner channel estimation sequence and each portable terminal correspondence in the embodiment of the invention;

Fig. 5 is the structure chart of joint-detection A matrix in the embodiment of the invention;

Fig. 6 is system emulation result in the embodiment of the invention.

Embodiment

Below in conjunction with drawings and Examples technical scheme of the present invention is described in detail.

For a TD time slot of propagating on wireless channel, it can be subjected to the convolution modulation of wireless channel impulse response.This impulse response is made up of two parts: 1, and the decline that is caused by multipath effect: because the duration (675 μ s) of a TD time slot is much smaller than the coherence time of space channel, so this part can think in a slot time section it is approximate fixing; 2, by the phase deviation that Doppler effect caused

Side-play amount

Linear in time variation in a time slot duration, as shown in Figure 2, c wherein _iRepresent i chip on this time slot, each bar oblique line represent on the corresponding footpath phase pushing figure (since each bar radially with the motion of mobile terminals direction between angle different, the therefore slope of every oblique line, promptly

Also different).The space channel of certain portable terminal on a slot length launched successively by chip, obtains:

$\left\{\begin{array}{c}h(\mathrm{chip}\_1)=[{\mathrm{cof}}_{\mathrm{fadmg}\_1}\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&pi;f}}_d^1-{\mathrm{<figure-callout\; id="1"\; label="t\; chip"\; filenames="H2009100065791E0000031.png,H2009100065791E0000041.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{chip}}},{\mathrm{cof}}_{\mathrm{fadmg}\_2}\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="f\; d"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">f</figure-callout>}}_d^{}\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="t\; chip"\; filenames="H2009100065791E0000031.png,H2009100065791E0000041.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{chip}}},...,{\mathrm{cof}}_{\mathrm{fadmg}\_L}\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{f}_d^L\&CenterDot;t_{\mathrm{chip}1}}]\\ .......\\ h(\mathrm{chip}\_864)=[{\mathrm{cof}}_{\mathrm{fadmg}\_1}\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="1"\; label="f\; d"\; filenames="H2009100065791E0000031.png,H2009100065791E0000041.png"\; state="\{\{state\}\}">f</figure-callout>}}_d^{}\&CenterDot;t_{\mathrm{chip}864}},{\mathrm{cof}}_{\mathrm{fadmg}\_2}\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="f\; d"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">f</figure-callout>}}_d^{}\&CenterDot;t_{\mathrm{chip}864}},...,{\mathrm{cof}}_{\mathrm{fadmg}\_L}\&CenterDot;e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100065791E0000031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{f}_d^L\&CenterDot;t_{\mathrm{chip}864}}]\end{array}\right.---\left(\text{1}\right)$

Wherein, the channel impulse response (span of i is 1～864) on i chip of h (chip_i) expression, cof _{Fading_k}The fading coefficients of representing the k footpath,

Represent that k directly goes up by Doppler frequency shift

The phase pushing figure on i chip that is caused.

Below abbreviate the phase pushing figure of received signal on every chip that Doppler frequency shift caused as the Doppler frequency deviation value.

Before carrying out following step, need terminal is done following setting: preserve the scope interval of the absolute value of predefined n (n 〉=1) Doppler frequency deviation value on the terminal, the absolute value of all possible Doppler frequency deviation value has been contained in this n scope interval piecemeal; In addition, also preserve on it and the interval corresponding comparison slot s lot[i of each scope] (value of i is 1～n), be slot[i] corresponding with i scope interval, this corresponding relation can be: along with the scope interval is close to infinity gradually, the interval corresponding comparison time slot of each scope is close to current time slots gradually, can be interpreted as that promptly the Doppler frequency deviation value absolute value that drops in a certain scope interval is big more, pairing relatively time slot is the closer to this time slot.Wherein, relatively time slot is current time slots certain time slot before, and it both may be that timeslot number also may be certain time slot in current time slots place subframe certain subframe before less than certain time slot of current time slots in the subframe of current time slots place.

Preferably, set n=2, the scope interval of promptly setting Doppler frequency deviation value absolute value is respectively: interval A=[0, X), and interval B=[X ,+∞], the value of X can be determined by engineering is actual.The comparison time slot of interval A correspondence is the time slot that has identical timeslot number in the last subframe with current time slots; The comparison time slot of interval B correspondence is the TS0 time slot in the subframe of current time slots place.Why adopting these two time slots time slot as a comparison, is that the channel estimating after so just can guaranteeing is enforceable because in the midamble code section of these two time slots training sequence is arranged all the time.Certainly, relatively time slot also can be selected current time slots other any time slot before for use, as the last time slot of current time slots, but need guarantee in the midamble code section of this comparison time slot training sequence is arranged.

The present invention eliminates the Doppler frequency shift factor by some steps

Influence to portable terminal correctly receives, demodulation symbol produces comprises:

The absolute value of the Doppler frequency deviation value on (1) the anticipation current time slots is positioned at above-mentioned which scope interval;

(2) go out the phase pushing figure of received signal on every chip lengths that causes by Doppler frequency shift by comparing the phase difference estimation of the interval pairing relatively time slot of current time slots and this scope on the correspondence footpath;

(3) according to this phase pushing figure in conjunction with existing associated detection technique, eliminate the phase deviation of the receiving symbol that Doppler frequency shift causes by revising A matrix in the joint-detection.

(4) receiving symbol is separated timing, in demodulation, the Doppler frequency deviation that estimates is before carried out fine control.

Behind execution in step (1) and (2), can go out the Doppler frequency deviation value of this portable terminal according to a preliminary estimate; And can compensate the deviation that causes by Doppler frequency shift by execution in step (3) follow-up.Estimate the Doppler frequency deviation value of this portable terminal on this time slot after the execution in step (4) more accurately.

In the step (1), the anticipation value of described Doppler frequency deviation for this portable terminal in the estimated Doppler frequency deviation value that goes out of last a processing time slot.Has the estimated Doppler frequency deviation value that goes out of the time slot of identical timeslot number for handling in the last subframe under the preferable case with current time slots.

In the step (2), comparison current time slots and the phase difference of comparison time slot on the correspondence footpath are meant: the channel estimation sequence that at first obtains these two time slots; Then two sequences are carried out by the footpath coupling; After obtaining the last phase difference in corresponding footpath,, obtain the phase pushing figure of this portable terminal on every footpath, every chip lengths divided by corresponding chip-spaced.Wherein, in order to obtain channel estimation sequence, need intercept midamble code to corresponding time slot, do the FFT conversion, some actions such as IFFT inverse transformation, the steiner method after improving is adopted in the realization of channel estimating, belong to existing technology category, no longer give unnecessary details at this.

In addition, current time slots carried out channel estimating after, this estimated sequence can be preserved.Like this, when follow-up this time slot as a comparison during time slot,, directly use this channel estimation sequence channel estimation sequence of time slot as a comparison because therefore the channel estimation sequence of preserving this time slot in the terminal can omit the channel estimation process to this time slot.

From step (3) as can be seen, eliminating the Doppler frequency shift deviation is that prior art-joint-detection in conjunction with TD realizes.But in the present invention the joint-detection matrix A that generates is revised, specifically comprise: the b vector of the A matrix of generation is formed by revised channel estimation sequence and compound spreading code convolution, and revised channel estimation sequence is to constitute by Doppler frequency deviation value on the average channel estimation sequence modulation that estimates, and has guaranteed that promptly revised channel estimation sequence no longer is changeless in a time slot.

Preferably, under typical TD portable terminal high-speed motion scene, only need most powerful path to this portable terminal carry out the estimation of phase pushing figure and the channel estimating of most powerful path is revised, and revise joint-detection A matrix, eliminate the Doppler frequency shift deviation.

The accuracy of estimating for raising in the step (4), the Doppler frequency deviation that estimates is before carried out fine control separating timing, and with the Doppler frequency deviation value of the maximum in the Doppler frequency deviation value of the most powerful path after the fine control or each the footpath Doppler frequency deviation value, and preserve this value Doppler frequency deviation anticipation value as next processing time slot in this portable terminal as this time slot.

In sum, as shown in Figure 3, portable terminal repeats following steps to each time slot data that comprises this mobile terminal data that it receives:

Step 301: as anticipation value (to first receiving slot, this anticipation value is 0 or preassigned value), and which scope interval the absolute value of definite this anticipation value drops on to portable terminal with the last one Doppler frequency deviation estimated value of handling time slot of preserving on it;

Step 302: choose corresponding comparison time slot according to that scope interval that falls into, and intercept the training sequence of this comparison time slot, do channel estimating for the first time with improved steiner method, obtain the average channel impulse response of each portable terminal in this comparison slot time section;

Step 303: intercept the training sequence of this time slot, do secondary channel estimating, estimate each portable terminal in the average channel impulse response of this time slot in the period;

Certainly, the order that this time slot and comparison time slot are carried out channel estimating in no particular order, as long as obtain average channel impulse response in these two time slots.

Step 304: the channel estimation value of current time slots and comparison time slot is mated by portable terminal, corresponding footpath, two channel sequence after the coupling are carried out phase place by the footpath and are subtracted each other, again divided by the chip-spaced length between current time slots and the comparison time slot, estimate the phase pushing figure of each portable terminal received signal on every footpath, every chip that Doppler frequency shift causes, i.e. the Doppler frequency deviation value of each portable terminal on every footpath;

Step 305: will be multiplied by spreading factor SF by the phase pushing figure of every portable terminal on every footpath, every chip that step 304 obtained, obtain the phase deviation factor of every portable terminal on every footpath, every symbol lengths duration, and with the channel estimation sequence of this factor correction current time slots, carry out convolution algorithm with this revised estimation channel sequence and compound spreading code, make up revised joint-detection A matrix;

Step 306: utilize revised A matrix that the signal of the current time slots of reception is done joint-detection, obtain the demodulation symbol of each portable terminal once.

Step 307: (this standard modulation symbols is the standard complex modulation symbol that transmitter modulation back sends with hithermost standard modulation symbols in these demodulation symbols and the planisphere, for example concerning the QPSK modulation, standard modulation symbols is exactly :+i, 1,-1,-i) do the phase bit comparison, the gained phase difference is done smoothing processing, obtains phase pushing figure; Then with the Doppler frequency deviation value of this portable terminal that estimates in this phase pushing figure fine tuning step 304 at this time slot upper signal channel most powerful path;

Step 308: next receiving slot of determining the Doppler frequency deviation value of this time slot and being saved in this portable terminal is done with reference to relatively using.The Doppler frequency deviation value of described time slot is the Doppler frequency deviation value on the most powerful path of this portable terminal after step 307 fine tuning, perhaps maximum Doppler frequency deviation value or above-mentioned two weighted sum in each footpath of this portable terminal.

When portable terminal is under the high-speed motion scene, can be only in above-mentioned steps 305～308 most powerful path of this portable terminal be carried out the estimation of phase pushing figure and the channel estimating of most powerful path is revised, and revise joint-detection A matrix, to eliminate the Doppler frequency shift deviation.

With an instantiation the present invention is further described below.

Suppose that certain TD portable terminal is carrying out the voice service of 12.2kbps, this service feature is that this portable terminal occupies a fixedly time slot on each subframe, descending spreading factor SF=16.

Terminal is carried out initial configuration: preestablish 2 sections scope intervals: interval A=[0,1*10 by the Doppler frequency deviation absolute value ^-3Radian/chip), interval B=[1*10 ^-3Radian/chip ,+∞).(boundary in two intervals of selected this equals 1*10 ^-3Radian/chip, the speed of corresponding mobile terminal is 120km/h, maximum doppler frequency f _{D max}Be 222Hz).

Set the comparison time slot in two corresponding scope intervals: corresponding interval A, relatively time slot be in the last subframe with the time slot of the identical timeslot number of current time slots; Corresponding interval B, relatively time slot is the TS0 time slot of this subframe.

The anticipation value of setting initial Doppler frequency deviation value is 0.

This portable terminal is repeated below the step operation to the time slot that comprises this mobile terminal data in the every subframe that receives:

Step 1: according to the absolute value of the Doppler frequency deviation value of this time slot of anticipation drop on choose accordingly in which scope interval one relatively time slot (for first subframe, the anticipation value is 0, to subframe afterwards, the anticipation value is the Doppler frequency deviation value that has identical timeslot number time slot in the last subframe with current time slots)

When the anticipation value falls into interval A, think that portable terminal is in little Doppler frequency deviation state, choose in the last subframe and the time slot of the identical timeslot number of current time slots time slot as a comparison;

When the anticipation value falls into interval B, think that portable terminal is in big Doppler frequency deviation state, therefore need do more accurate Doppler frequency deviation and estimate, choose in this subframe TS0 time slot time slot as a comparison.

Step 2: channel estimating is done in the intercepting relatively training sequence of time slot, obtains each portable terminal at the average channel response ch_est1 that compares on the time slot.The concrete grammar of channel estimating adopts the steiner method after improving, and can be divided into following two sub-steps:

Step 2.1, intercepting be the training sequence receiver_mid of time slot relatively ₁Do the FFT conversion, divided by the FFT conversion of basic training sequences mid_basic, the result done the IFFT conversion more again, obtain channel estimation sequence (Channel_Estimation):

Channel_Estimation＝IFFT(FFT(receiver_mid ₁)/FFT(mid_basic)) (2)

Wherein basic training sequences is given each sub-district and is notified portable terminal by system's original allocation.

Step 2.2, as shown in Figure 4, power is used as noise path greater than the footpath of ε and is removed in the channel estimation sequence of each portable terminal correspondence that step 2.1 is obtained, and remaining sequence ch_est1 is the average channel response of each portable terminal in time slot relatively.(wherein, ε=r ²σ ², r ²Expression thresholding signal to noise ratio, σ ²The expression noise power, the value of r and σ can be chosen r＜1 according to engineering is actual).

During specific implementation, when time slot relatively is when having the time slot of identical timeslot number with current time slots in the last subframe, owing in the processing of a last subframe, this time slot was done channel estimating, therefore only need in portable terminal, to increase the storage of this channel estimating, and in this step, read this storage and get final product, and need not to do again step 2.1 and 2.2;

Step 3: the training sequence of intercepting current time slots is done channel estimating, obtains the average channel response ch_est2 of each portable terminal on current time slots.The concrete grammar of channel estimating adopts the steiner method after improving, and can be divided into two sub-steps (as step 2.1,2.2 is described), repeats no more here.

After obtaining current time slots upper signal channel estimated sequence, store this sequence.

Step 4, respectively the estimated sequence of the average channel response of current time slots and comparison time slot is pressed portable terminal and footpath coupling, the average channel response of the most powerful path of each portable terminal is carried out phase place subtracts each other, again divided by the interval number of chips between current time slots and comparison time slot, obtain the phase pushing figure of received signal every chip on most powerful path of this portable terminal of causing by Doppler frequency shift, i.e. the Doppler frequency deviation value of this portable terminal on most powerful path:

${\mathrm{phase}\_\mathrm{estimation}}_{\mathrm{per\; chip}}^{\mathrm{strongest\; tap}}=\frac{{\mathrm{phase}}_{\mathrm{strongest\; tap}}^{\mathrm{ch}\_\mathrm{est}2}-{\mathrm{phase}}_{\mathrm{strongest\; tap}}^{\mathrm{ch}\_\mathrm{est}1}}{N_{\mathrm{chip}}}---\left(3\right)$

This value can be thought the rough estimate evaluation (also needing to carry out fine control in step 6) of Doppler frequency deviation.Wherein, phase represents to get the phase bit arithmetic, and strongest tap represents most powerful path, promptly each the footpath channel response in prominent one the footpath, N _ChipExpression current time slots and the number of chips of relatively being separated by between time slot:

For the TS0 time slot of in step 1, choosing this subframe time slot of making comparisons, N _Chip=current time slots sequence number * 864+352, wherein 352 is descending synchronous code, protection interval and three total chip lengths of uplink synchronous code.

For the time slot of in step 1, choosing identical timeslot number in subframe time slot as a comparison, current time slots and relatively be spaced apart a sub-frame length, chip-spaced N between time slot _Chip=6400.

Among this embodiment, preferably only the Doppler frequency deviation value of each terminal use's most powerful path is estimated, adopted method for optimizing can reduce the complexity that terminal realizes; The reason of its establishment is under typical portable terminal high-speed motion scene, the general wireless signal (being that radio wave can arrive portable terminal from antenna for base station direct projection ground) that all exists a line of sight, this line of sight is the principal element that influences received signal quality, that is the most powerful path that estimates;

Step 5: the above-mentioned received signal that estimates phase pushing figure of every chip on most powerful path is multiplied by spreading factor, revise the channel estimation sequence of current time slots, and carry out convolution algorithm with compound spreading code with revised channel estimation sequence, form the joint-detection A matrix of revising.Specifically be divided into four sub-steps:

Step 5.1, will be multiplied by spreading factor SF, obtain the phase deviation factor of received signal on the every symbol of most powerful path by the phase pushing figure of received signal that step 4 obtains every chip on most powerful path:

${\mathrm{phase}\_\mathrm{estimation}}_{\mathrm{per\; symbol}}^{\mathrm{strongest\; tap}}=\mathrm{SF}*\mathrm{phase}\_{\mathrm{estimation}}_{\mathrm{per\; chip}}^{\mathrm{strongest\; tap}}---\left(4\right)$

On the most powerful path of step 5.2, current time slots average channel estimation sequence that the phase pushing figure of received signal on the every symbol lengths of most powerful path compensated in the step 3 to be obtained, obtain revised channel estimation sequence:

$\mathrm{channel}\_{\mathrm{estimation}}_{\mathrm{symbol}\_n}^{\&prime;\mathrm{tap}\_\mathrm{strongest}}=\mathrm{channel}\_{\mathrm{estimation}}^{\mathrm{strongest\; tap}}*e^{-j*2\mathrm{\&pi;}*n*\mathrm{phase}\_{\mathrm{estimation}}_{\mathrm{per\; symbol}}^{\mathrm{strongest\; tap}}}---\left(5\right)$

Wherein, channel_estimation ^{Strongest tap}Be illustrated in the most powerful path of this portable terminal in the current time slots average channel estimation that obtains in the step 3, n represents n modulation symbol.

Revised channel estimation sequence no longer is changeless in this time slot, but by sign bit received the modulation of the estimated Doppler frequency deviation that goes out.

Step 5.3, the spreading code by each portable terminal, channel code, scrambler multiply each other and obtain the compound spreading code of each portable terminal respectively

$c_i^{\mathrm{user}}=\mathrm{spreading}\_{\mathrm{code}}_i^{\mathrm{user}}*\mathrm{channeliasation}\_{\mathrm{code}}_i*\mathrm{scrambling}\_{\mathrm{code}}_i---\left(6\right)$

The compound spreading code of each portable terminal that generates in step 5.4, the revised channel estimation sequence of utilizing acquisition in the step 5.2 and the step 5.3 comes tectonic syntaxis to detect matrix A.

The structure of A matrix is with reference to Fig. 5.It is made of N V piece, and N represents the number of modulation symbol, and each V piece is arranged in by U b vector, and U represents the portable terminal number, and each b vector is obtained by revised channel estimating and compound spreading code convolution:

${\stackrel{\&RightArrow;}{b}}_{\mathrm{symbol}\_n}^{\mathrm{user}\_u}=\mathrm{Channel}\_{{\mathrm{Estimation}}^{\&prime;}}_{\mathrm{symbol}\_n}^{\mathrm{user}\_u}\&CircleTimes;c^{\mathrm{user}\_u}---\left(7\right)$

Wherein, Represent u portable terminal channel estimating after the correction on n the symbol, c ^User_uRepresent u the compound spreading code of portable terminal;

The expression convolution algorithm.

Step 6: utilize revised A matrix that the data segment of current time slots is done joint-detection, obtain the demodulation symbol of each portable terminal

d＝(I+σ ^-2A ^HA) ^-1·A ^He (8)

Promptly realized the Doppler frequency shift of demodulation symbol is eliminated.Wherein, I representation unit matrix, σ represents noise power, e represents the data segment chip that receives; A ^HThe hermitian conversion of representing matrix A, A ^-1The inverse transformation of representing matrix A.

Step 7: in order to obtain more accurate Doppler frequency deviation estimated value,, specifically may further comprise the steps to the rough estimate evaluation of the Doppler frequency deviation that estimates in the step 4 accent of running business into particular one:

A, the demodulation symbol that obtains in the step 6 is done the phase bit comparison with the modulation symbol of standard, the gained phase difference is done smoothing processing, and gained is the rough estimate evaluation of fine tuning Doppler frequency deviation as a result, specifically comprises:

A1, will obtain the modulation symbol d of demodulation symbol with standard _StdPhase place compare, the gained phase difference is done on average:

Δphase′＝AVG(phase(d)-phase(d _std)) (9)

Herein, AVG represents the computing of asking average, specifically is meant all (all users) done on average by the demodulation symbol that joint-detection obtained.

A2, respectively the rough estimate evaluation that estimates Doppler frequency deviation in the step 4 is carried out fine tuning with acquisition Δ phase ':

$\mathrm{\&Delta;phase}\_e{\mathrm{stimation}}_{\mathrm{per\; chip}}^{\mathrm{tap}\_\mathrm{strongest}}=\mathrm{phase}\_{\mathrm{estimation}}_{\mathrm{per\; chip}}^{\mathrm{tap}\_\mathrm{strongest}}+\frac{{\mathrm{\&Delta;phase}}^{\&prime;}}{\mathrm{SF}}---\left(10\right)$

This value can be thought

Be the Doppler frequency deviation value of this portable terminal on this time slot, can obtain Doppler frequency shift value f according to this value _d

The phase pushing figure of most powerful path after B, the adjustment that will in steps A 2, obtain

Doppler frequency deviation value as this time slot is saved in the portable terminal, the anticipation amount when handling as next subframe.

To next son frame data repeating step 1-7.

As shown in Figure 6, as can be seen, after employing the method for the invention, the error rate of portable terminal obviously reduces.

Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

Claims (13)

1. the method for estimation of Doppler frequency deviation value in the TD SDMA TD-SCDMA system is characterized in that,

Portable terminal is after receiving the time slot that contains this mobile terminal data, by comparing the Doppler frequency deviation value that a current time slots and a phase difference that compares the channel estimation sequence of time slot obtain the current time slots received signal.

2. the method for claim 1 is characterized in that,

Preserve interval the reaching and the interval corresponding comparison time slot of each scope of scope of the absolute value of predefined n Doppler frequency deviation value on the described portable terminal, wherein, this n scope interval contained the absolute value of all possible Doppler frequency deviation value, n 〉=1 piecemeal;

Described portable terminal is meant by the received signal Doppler frequency deviation value that comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot obtain this portable terminal:

The absolute value of the anticipation value of the Doppler frequency deviation value of judgement current time slots is positioned at above-mentioned which scope interval;

By the interval definite corresponding relatively time slot of the described scope of judging;

By relatively current time slots and the phase difference estimation of described relatively time slot on the correspondence footpath go out the phase pushing figure of received signal on the every chip lengths of this time slot that is caused by Doppler frequency shift.

3. method as claimed in claim 2 is characterized in that,

The anticipation value of the Doppler frequency deviation value of described current time slots is the Doppler frequency deviation value of a processing time slot on this portable terminal;

A Doppler frequency deviation value of handling time slot is meant on described this portable terminal: the Doppler frequency deviation value on the estimated most powerful path of this portable terminal at this time slot that obtains when containing the time slot of this mobile terminal data, perhaps this portable terminal maximum Doppler frequency deviation value or above-mentioned two weighted sum in each footpath of this time slot on handling of preserving in this portable terminal.

4. method as claimed in claim 2 is characterized in that,

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

Intercept the described relatively training sequence of time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot;

The training sequence of intercepting current time slots is done channel estimating, estimates the average channel impulse response of each portable terminal in current time slots;

Described current time slots is subtracted each other by the corresponding phase place of directly carrying out with this portable terminal part of the relatively average channel impulse response of time slot, divided by the chip-spaced length between above-mentioned two time slots, obtain the phase of received signal side-play amount of this portable terminal on every footpath, every chip that Doppler frequency shift causes again.

5. as claim 2 or 4 described methods, it is characterized in that,

When n=2, described scope interval comprises: A=[0, X), B=[X, + ∞), the pairing relatively time slot of the interval A of described scope is the time slot that has identical timeslot number in the last subframe with current time slots, the pairing relatively time slot of described scope interval B is the TS0 time slot in the subframe of current time slots place, wherein, the value of X is determined according to engineering is actual.

6. method as claimed in claim 5 is characterized in that,

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

When time slot relatively is TS0 time slot in this frame, intercept the training sequence of described TS0 time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot; When described relatively time slot is when being in time slot with time slot with current time slots in the previous frame, obtain the described relatively average channel impulse response of time slot according to the keeping records of described portable terminal;

The training sequence of intercepting current time slots is done channel estimating, estimates each portable terminal in the average channel impulse response of current time slots in the period;

Described portable terminal carries out phase place with the channel estimation value of most powerful path in current time slots and the described relatively time slot and subtracts each other, divided by current time slots and the described relatively chip-spaced length of time slot, obtain the phase of received signal side-play amount of this portable terminal on every chip that Doppler frequency shift causes again.

7. the compensation method of Doppler frequency shift in the TD SDMA TD-SCDMA system is characterized in that,

Portable terminal is after receiving the time slot that contains this mobile terminal data, by comparing the Doppler frequency deviation value that a current time slots and a phase difference that compares the channel estimation sequence of time slot obtain the current time slots received signal, and, in joint-detection, described received signal is revised in conjunction with joint-detection.

8. method as claimed in claim 7 is characterized in that,

Preserve interval the reaching and the interval corresponding comparison time slot of each scope of scope of the absolute value of predefined n Doppler frequency deviation value on the described portable terminal, wherein, this n scope interval contained the absolute value of all possible Doppler frequency deviation value, n 〉=1 piecemeal;

Described portable terminal is meant by the received signal Doppler frequency deviation value that comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot obtain this portable terminal:

The absolute value of the anticipation value of the Doppler frequency deviation value of judgement current time slots is positioned at above-mentioned which scope interval;

By the interval definite corresponding relatively time slot of the described scope of judging;

By relatively current time slots and the phase difference estimation of described relatively time slot on the correspondence footpath go out the phase pushing figure of received signal on the every chip lengths of this time slot that is caused by Doppler frequency shift.

9. method as claimed in claim 8 is characterized in that,

The anticipation value of the Doppler frequency deviation value of described current time slots is the Doppler frequency deviation value of a processing time slot on this portable terminal;

A Doppler frequency deviation value of handling time slot is meant on described this portable terminal: the Doppler frequency deviation value on the estimated most powerful path of this portable terminal at this time slot that obtains when containing the time slot of this mobile terminal data, perhaps this portable terminal maximum Doppler frequency deviation value or above-mentioned two weighted sum in each footpath of this time slot on handling of preserving in this portable terminal.

10. method as claimed in claim 8 is characterized in that,

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

Intercept the described relatively training sequence of time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot;

The training sequence of intercepting current time slots is done channel estimating, estimates the average channel impulse response of each portable terminal in current time slots;

Described current time slots is subtracted each other by the corresponding phase place of directly carrying out with this portable terminal part of the relatively average channel impulse response of time slot, divided by the chip-spaced length between above-mentioned two time slots, obtain the phase of received signal side-play amount of this portable terminal on every footpath, every chip that Doppler frequency shift causes again.

11. method as claimed in claim 8 is characterized in that,

Described portable terminal obtains this portable terminal by comparison current time slots and the described relatively phase difference of the channel estimation sequence of time slot and specifically comprises in the Doppler frequency deviation value of current time slots received signal:

When time slot relatively is TS0 time slot in this frame, intercept the training sequence of described TS0 time slot, do channel estimating, estimate the average channel impulse response of each portable terminal in this comparison time slot; When described relatively time slot is when being in time slot with time slot with current time slots in the previous frame, obtain the described relatively average channel impulse response of time slot according to the keeping records of described portable terminal;

The training sequence of intercepting current time slots is done channel estimating, estimates each portable terminal in the average channel impulse response of current time slots in the period;

Described portable terminal carries out phase place with the channel estimation value of most powerful path in current time slots and the described relatively time slot and subtracts each other, divided by current time slots and the described relatively chip-spaced length of time slot, obtain the phase of received signal side-play amount of this portable terminal on every chip that Doppler frequency shift causes again.

12. as any described method in the claim 7～11, it is characterized in that,

Described received signal to each portable terminal is revised specifically in joint-detection to be comprised:

The described phase pushing figure that obtains be multiply by behind the spreading factor SF compensate described each portable terminal in the average channel impulse response of current time slots in the period by the footpath;

Multiply each other by spreading code, channel code, the scrambler of each portable terminal and to obtain the compound spreading code of each portable terminal respectively;

Utilize the average channel impulse response after the described compensation and the compound spreading code tectonic syntaxis of described each portable terminal to detect matrix A, and the data segment in the current time slots is carried out joint-detection, obtain revised demodulation symbol with described joint-detection matrix A.

13. method as claimed in claim 12 is characterized in that, also comprises:

Do the phase bit comparison with the described demodulation symbol that obtains with standard modulation symbols in the planisphere, the gained phase difference is made smoothing processing to the phase place frequency deviation value and/or the maximum phase place frequency deviation value of the most powerful path of each portable terminal, and the result after handling is preserved as the Doppler frequency deviation value of this time slot.

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