CN1960226B - Apparatus for performing initial synchronization and frame synchronization in mobile communications system and method thereof - Google Patents

Abstract

An apparatus for performing initial synchronization and frame synchronization in a mobile communications system and method thereof are disclosed. First of all, a method and apparatus for performing frame synchronization in a mobile communications system using a correlation value between a received signal and a reference vector for a phase according to one embodiment of the present invention are disclosed. Secondly, a method and apparatus for performing frame synchronization by considering all phase modulation possibility and frequency offsets according to another embodiment of the present invention are disclosed. Thirdly, a method and apparatus for performing initial estimation in a manner of dividing at least one subframe received from a base station by a UE in the course of cell search into at least two areas, calculating a correlation for each of the at least two areas and using a maximum value of the calculated correlation value per area are disclosed.

Description

In mobile communication system, carry out the devices and methods therefor of initial synchronisation and frame synchronization

The application requires in the rights and interests of the korean patent application No.P10-2006-006428 of the korean patent application No.P10-2005-0103509 of application on October 31st, 2005 and application on January 20th, 2006, and it is combined in this as the reference data set as setting forth fully herein.

Technical field

The present invention relates to mobile communication system, especially, relate to a kind of devices and methods therefor that is used for carrying out initial synchronisation and frame synchronization in mobile communication system.

Background technology

Usually, the cell search process of being undertaken by subscriber equipment (hereinafter, being abbreviated as UE) in the TD-SCDMA system is the process that is used to obtain downlink synchronization code (SYNC-DL), basic training sequences sign indicating number, scrambling code, frame synchronization, BCH (broadcast channel) information, chip timings information or the like.And this cell search process is normally carried out by 4 following steps.

Fig. 1 is the flow chart according to the cell search process of correlation technique.

1) initial synchronisation search procedure (search DwPTS)

At first, UE need not to be used for the information of Cell searching, uses 32 available SYNC-DL sign indicating numbers to carry out initial synchronisation in DwPTS (down link pilot timeslot).By this step, UE will find SYNC-DL sign indicating number and the timing synchronous points of using in the sub-district among 32 available SYNC-DL sign indicating numbers.

2) basic training sequences and scrambling code identification

Because the DwPTS sign indicating number that finds by above initial synchronisation search procedure is corresponding to a code character with four basic training sequences, UE searches for the basic training sequences of using in the sub-district from four basic training sequences.Because basic training sequences is relevant with scrambling code,, can find this scrambling code if obtained basic training sequences.

3) frame synchronization is caught (the control multiframe is synchronous)

The MIB (main information piece) of the QPSK phase modulated search BCH multiframe of the DwPTS of UE by being used for the P_CCPCH training sequence.

4) BCH information capture (reading BCH)

UE reads BCH by the MIB that uses search and obtains BCH information.

At length explain frame synchronization acquisition procedure below according to correlation technique.

At first, because BCH has 20ms Transmission Time Interval (hereinafter, being abbreviated as TTI) in the TD-SCDMA system, UE must know whether that BCH is present in the next frame, and begins in the position of 20ms TTI here.

In order to notify the starting position of UE BCH, the base station under the situation of modulation DwPCH based on the phase place carry out phase modulation of the first time slot training sequence.And, one sub-image duration phase modulated value similarly kept.

The four phase modulation values that obtain during four continuous subframes are known as " quaternary phase place (phasequadruple) ", and have the quaternary phase place of two types, S1 and S2.Table 1 illustrates the implication of the quaternary phase place of two types.

[table 1]

Example	The quaternary phase place	Implication
			S1	135°，45°，225°，135°	P-CCPCH is present in ensuing four subframes
S2	315°，225°，315°，45°	P-CCPCH is not present in ensuing four subframes

In table 1, P-CCPCH (Primary Common Control Physical Channel) is the physical channel that transmission channel BCH is mapped to it.

In correlation technique, " quaternary phase place " detected four sub-image durations, and the quaternary phase place that judges whether then to detect is corresponding to S1.If it is judged as S1, then judge the P-CCPCH that exists from next subframe.Start the reception of the BCH that transmits by P-CCPCH then.

Especially, the process that is used to detect the quaternary phase place comprises the process of the phase modulation values that is used to detect the downlink synchronization code that is used for each subframe, and it is made up of following step.

At first, detect the phase value of the training sequence code that receives and the phase value of downlink synchronization code.

Subsequently, the correlation of acquisition between the phase value of two sign indicating numbers that detect.By the correlation that obtains is carried out " arctangent (arc tangent) ", find the phase modulation of downlink synchronization code then.

After this, the quaternary phase place is compared with phase value S1 or S2 in table 1, this quaternary phase place is the phase value four that obtain in the above described manner sub-modulation image durations.

As this comparative result, if the quaternary phase place that obtains receives BCH corresponding to S1 in ensuing four subframes.If the quaternary phase place that obtains does not correspond to S1, it judges that BCH is not present in ensuing four subframes.Therefore, the process that is used to detect the quaternary phase place is repeatedly carried out.

But, using arctangent according to correlation technique to detect under the situation of chopping phase place value of downlink synchronization code, this arctangent operation is normally by using chart for the lookup table of effectively implementing to shine upon to replace.Therefore, be used for the memory of operating provision accurately, will exceedingly increase the capacity of memory because the tabular value of q.s need be stored in.

And because the phase value of the modulation of downlink code also can the distortion owing to frequency shift (FS), it is difficult to calculate phase modulation values accurately by the method for prior art.

First process of the initial synchronisation search in the process of Cell searching may be influential to power consumption, automatic frequency control (AFC), synchronous tracer performance or the like.In addition, because the initial synchronisation search should repeatedly be carried out repeatedly, it need satisfy excessive calculating and memory.

Usually, by the downlink synchronization code (SYNC-DL) of the current present use of current area by by detecting at signal that receives from the base station and the correlation between the reference signal.In 3GPPTDD LCR (low spreading rate) system, the method for carrying out initial synchronisation from the signal that receives comprises of following scheme.

At first, there is the peaked method of correlation of using.Especially, initial synchronisation is to carry out from the correlation maximizing of the subframe of a reception by use.Therefore, this method can easily realize.

But because the level of received signal promptly changes in having the multidiameter fading channel environment of low SNR, it is difficult to improve the performance of time correlation.In addition, under the situation that the sampling that reduces received signal takes place, time error increases.

Secondly, exist by using the another kind of method of the mean value that calculates by several subframe accumulated correlation values.Especially, obtain in signal that receives from the base station and the correlation between the downlink synchronization code (SYNC-DL).This correlation is added up by several subframes, and obtains mean value then.And initialization is used for peaked mean value by search synchronously and carries out.

If maximum is to be found by the mean value that the correlation that adds up by several subframes produces by acquisition, it can obtain reliable temporal correlation by reducing because the level of the received signal of the influence of high fading rate changes.But owing to the correlation of 32 sign indicating numbers that are used for receiving by several subframes should be stored at every turn, the memory increase is inevitable.And, the signal that receives at over-sampling, and be used for sequentially finding under the situation that the comparator of maximum correlation is implemented, relatively and storage will repeatedly implement with [6400 * 32 * over-sampling] as many.

In addition, because the number that it can not subframe is set to indefinite number, therefore, it is limited in specified number or amount.So if take mean value, although because the error amount of the correlation that noise distortion can be considered is added up, the degeneration of performance is inevitable.

The 3rd, there is the another kind of method that has the synchronous code of high occurrence number and be used for the synchronous points of several subframes of following the tracks of of using.Consider the probability of judging by several subframes, the occurrence number that has maximum correlation in source code is high.Therefore, use frequency of occurrences debug relevant, and obtain to have the mean value of the time candidate that keeps strong.

If have only the index (index) of a sign indicating number to have maximum correlation value for a subframe, and this correlation is stored, and it can be reduced to the necessary memory capacity of subframe significantly.But the subframe that should observe q.s is so that follow the tracks of sign indicating number and the synchronous points that has high occurrence number for several subframes.If observe less subframe, accuracy is lowered.

In addition, if channel circumstance is poor, it can not find downlink synchronization code accurately.Therefore, need to observe more subframes.If not, accuracy is considerably reduced.

Summary of the invention

In view of the above, the present invention proposes a kind of devices and methods therefor that in mobile communication system, is used to carry out initial synchronisation and frame synchronization, eliminated one or more on its basis because the restriction of correlation technique and the problem of shortcoming.

An object of the present invention is to provide a kind of devices and methods therefor that is used for carrying out frame synchronization, need not to increase too much memory, and the possibility achieve frame is synchronous by it in mobile communication system.

Another object of the present invention provides a kind of devices and methods therefor that is used to carry out frame synchronization, can proofread and correct because the detection error that frequency shift (FS) produces by it.

Another object of the present invention provides a kind of devices and methods therefor that is used to carry out initial synchronisation, can be considerably reduced by its memory requirement.

Another object of the present invention provides a kind of devices and methods therefor that is used to carry out initial synchronisation, can carry out the initial synchronisation with high reliability by means of the frame of the very smallest number that is received by UE by it.

At first, disclose according to one embodiment of the invention be used for use in received signal and be used for the method and apparatus that correlation between the reference vector of phase place is carried out frame synchronization in mobile communication system.

Secondly, a kind of method and apparatus by considering that frame synchronization is carried out in all phase modulated possibilities and frequency shift (FS) of being used for according to another embodiment of the present invention is disclosed.

The 3rd, a kind of being used for to be decomposed at least two zones by UE at least one subframe that the process of Cell searching will receive from the base station disclosed, calculating at least two zones each correlation and use the peaked mode of the correlation that each zone calculates to carry out the method and apparatus of initial synchronisation.

To set forth additional advantage of the present invention, purpose and characteristics to a certain extent in the following description, when consulting following content or can learn from the practice of the present invention, will become apparent for those this areas those skilled in the art to a certain extent.Structure by especially pointing out in described specification and claim herein and appended accompanying drawing can realize and obtain purpose of the present invention and other advantage.

In order to realize these purposes and other advantage, with according to purpose of the present invention, as implementing herein and describing widely, a kind of method of in according to the portable terminal of mobile communication system of the present invention, carrying out downlink frame synchronization, comprise step: obtain the phase shift between downlink synchronization code and training sequence code, downlink synchronization code and training sequence code are included in the M number purpose of the subframe that links to each other that receives from the base station each, calculating between the phase vectors of the M number purpose phase-shift value that the reference vector and the expression of expression M number purpose reference phase value obtains plural inner product (complex inner product) and use the plural inner product estimated frames of calculating synchronous.

Preferably, this method further comprises step: the frequency shift (FS) of estimation between base station and portable terminal, wherein the plural inner product of Ji Suaning is differently used according to frequency shift (FS).

In another aspect of the present invention, a kind of device that is used for carrying out frame synchronization in mobile communication system, comprise: obtain the downlink synchronization code in being included in subframe and the phase detecting module of the phase shift between the training sequence code, the inner product computing module of the plural inner product of calculating between the phase vectors of the reference vector of representing M number purpose reference phase value and expression M number purpose phase-shift value, M number phase-shift value is to be carried out the frame synchronization detection module of frame synchronization for the plural inner product each acquisition and that use to calculate of the continuous subframe of M number purpose by phase detecting module.

Preferably, this device further comprises the frequency offset detection module of the frequency shift (FS) of detection between base station and portable terminal, and wherein the plural inner product of Ji Suaning is differently used according to the frequency shift (FS) that detects.

In another aspect of the present invention, a kind of method of in the portable terminal of mobile communication system, carrying out initial synchronisation, comprise step: calculate at least one or each regional maximum related value of a plurality of subframes of receiving from base station with a plurality of synchronous codes, each subframe is divided at least two zones and uses the maximum related value of calculating to carry out initial synchronisation for each each of at least two zones of at least one or a plurality of subframes.

Preferably, the step of carrying out initial synchronisation comprises step: will be used for the maximum related value combination of each zone and at least two subframes that are used for each synchronous code, with by having peaked zone among the combined value that is chosen in maximum related value, obtain to be used for the index and the time synchronized point of the synchronous code of initial synchronisation.

In another aspect of the present invention, a kind of method of in the portable terminal of mobile communication system, carrying out initial synchronisation, comprise step: first step, each regional maximum related value of the subframe that calculating receives from the base station with a plurality of synchronous codes, this subframe is divided at least two zones, second step, make up each regional maximum related value and each downlink synchronization code by at least two subframes repeatedly being carried out first step, and third step, use the value of combination to carry out initial synchronisation.

In another aspect of the present invention, a kind of device that is used for carrying out initial synchronisation in mobile communication system, comprise: be used to calculate device for each regional maximum related value of at least one or a plurality of subframes that receive from base station with a plurality of synchronous codes, each of at least one subframe is divided at least two zones, be used for the device of the maximum related value of at least one or a plurality of subframes in each zone and the combination of each synchronous code and be used to use the value of combination to carry out the device of initial synchronisation.

Preferably, this device further comprises the combined value of the maximum related value that is used to store each zone and each downlink synchronization code and has the storage arrangement of index of point of the maximum related value of each subframe, each zone or each downlink synchronization code.

Should be understood that above general introduction and following detailed description of the present invention are exemplary and illustrative, and be intended to the invention provides further instruction as claim.

Description of drawings

This accompanying drawing of following is included to provide further to be understood the present invention, and is combined into and constitutes the part of the application's book, and it illustrates embodiments of the invention, and can work to explain the principle of the invention with this specification.In this accompanying drawing:

Fig. 1 is the flow chart according to the cell search process of correlation technique;

Fig. 2 is the schematic diagram of the form of downlink subframe in 3GPP TDD LCR system;

Fig. 3 is the block diagram of device that is used to carry out frame synchronization according to one embodiment of the invention;

Fig. 4 and Fig. 5 are respectively the phase detection unit shown in Figure 3 and the detailed block diagram of inner product computing unit;

Fig. 6 is the figure of complex number plane;

Fig. 7 is the flow chart according to the execution initial synchronization method of another preferred embodiment of the present invention;

Fig. 8 is the auto-correlation that is used for the SYNC-DL sign indicating number of demonstration and the schematic diagram with cross-correlation of another yard;

Fig. 9 is according to being used to seek and being used for each regional correlation maximum of a preferred embodiment of the invention, has the schematic diagram of process of the index of this peaked synchronous code and time point;

Figure 10 is the schematic diagram according to the example that is used for synchronous points detection time of a preferred embodiment of the invention;

Figure 11 is the block diagram that is used to carry out the initial synchronisation device according to a preferred embodiment of the invention;

Figure 12 is the figure for the analog result of the situation that has different channels and frequency shift (FS); With

Figure 13 A to 13D is respectively according to the initial synchronisation histogram for the variation of the SNR of different channel (PA3, PB3, VA30, VA120).

Embodiment

Now with the preferred embodiment of the present invention will be described in detail, the accompanying drawing illustrated that its example is being followed.As possible, run through the identical reference number of this accompanying drawing and will be used to relate to identical or similar part.

At first, in following embodiments of the invention, technical characterictic of the present invention is applied to 3GPP TDD LCR (TD-SCDMA) system.And following embodiment only is exemplary, and technical characterictic of the present invention is equally applicable to the mobile communication system of other types.

Fig. 2 is the schematic diagram of the form of the downlink subframe in 3GPP TDD LCR system.The reference signal SYNC-DL that in 3GPP TFF LCR system, has the downlink synchronization code of 32 kinds.And the length of each yard is corresponding to 64 chips.With reference to figure 2, the training sequence code of P-CCPCH (MA) is included among the first downlink time slots Ts0, and downlink synchronization code SYNC-DL is set up the first downlink time slots Ts0 that is close to subframe." DwPTS " comprises 32 chip protection periods and 64 chip SYNC-DL sign indicating numbers.And this SYNC-DL sign indicating number is by using for of 32 classifications of each cell selecting.

Fig. 3 is the block diagram that is used to carry out frame-synchronizing device according to one embodiment of the invention.

With reference to figure 3, a kind of device that is used to carry out frame synchronization according to one embodiment of the invention, comprise: phase detection unit 10, it uses reference signal to obtain to be included in training sequence code (MA) in each subframe and the phase shift between the downlink synchronization code (SYNC-DL sign indicating number) from the received signal that transmit the base station; Inner product computing unit 20, it calculates conduct by plural inner product and the frame synchronization detecting unit 30 of phase detection unit 10 for the phase vectors of the vector expression of the phase shift of four continuous subframes acquisitions, and it uses the inner product value that calculates to detect frame synchronization.

Fig. 4 is the more detailed block diagram of phase detection unit 10.

Phase place based on the training sequence code (MA) the first downlink time slots Ts0 that is included in each subframe that transmits from the base station, be used to find the phase modulation values of downlink synchronization code (SYNC-DL sign indicating number), that is, the process of the phase shift between downlink synchronization code and training sequence code will be described in detail as follows with reference to figure 4.

At first, if the downlink synchronization code of the received signal in n subframe is represented as $r_s^{\left(n\right)}=[r_{s,0}^{\left(n\right)},...,r_{s,63}^{\left(n\right)}{]}^T,$ If the training sequence code of received signal is represented as $r_m^{\left(n\right)}=[r_{m,0}^{\left(n\right)},...,r_{m,127}^{\left(n\right)}{]}^T,$ If the downlink synchronization signal of the reference signal of being known the sixth of the twelve Earthly Branches in advance by UE is represented as s=[s ₀... s ₆₃] ^TAnd if the training sequence code of this reference signal is represented as m=[m ₀..., m ₁₂₇] ^T, then i downlink synchronization code of received signal and training sequence code can limit by equation 1 and equation 2 respectively.

[equation 1]

$r_{s,i}^{\left(n\right)}=\underset{i=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_i\·s_{i-l}\·e^{j{\mathrm{\φ}}_n}+{\mathrm{\η}}_i(i=0,...,63)$

[equation 2]

$r_{m,i}^{\left(n\right)}=\underset{i=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_i\·m_{i-l}+{\mathrm{\η}}_i(i=0,...,127)$

In this case, the length (unit of chip) of " L " expression multipath channel, " φ _n" expression n subframe the down link phase modulation values, " η _i" expression noise component(s) and " h _i" channel coefficients of expression indicating channel component.

In order to extract channel component and phase-modulated component, downlink synchronization code correlation detection module 11 and training sequence code correlation detection module 12 are searched respectively at received signal r _s ⁽ⁿ⁾, r _m ⁽ⁿ⁾With reference signal s, the autocorrelation between the m.This is to represent by following equation 3 and equation 4.In this case, " h ₀" be the channel component when correctly being mated synchronously.And according to s, the auto-correlation of m and cross-correlation performance can be supposed respectively

With

It is negligible very little value.

[equation 3]

$c_s^{\left(n\right)}=\frac{1}{64}{\left(r_s^{\left(n\right)}\right)}^T\·s^{*}=\frac{1}{64}\underset{i=0}{\overset{63}{\mathrm{\Σ}}}{r}_{s,i}^{\left(n\right)}\·s_i^{*}=\frac{1}{64}\underset{i=0}{\overset{63}{\mathrm{\Σ}}}(\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_i\·s_{i-l}\·e^{j{\mathrm{\φ}}_n}+{\mathrm{\η}}_i)\·s_i^{*}$

$=\underset{i=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_i\·e^{j{\mathrm{\φ}}_n}(\frac{1}{64}\underset{i=0}{\overset{63}{\mathrm{\Σ}}}{s}_{i-l}\·s_i^{*})+\frac{1}{64}\underset{i=0}{\overset{63}{\mathrm{\Σ}}}{\mathrm{\η}}_i\·s_i^{*}$

$={\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="H061E2927420061116E000061.png,H061E2927420061116E000131.png"\; state="\{\{state\}\}">h</figure-callout>}}_0\&CenterDot;e^{j{\mathrm{\&phi;}}_n}+\underset{i=1}{\overset{L-1}{\mathrm{\&Sigma;}}}{h}_i\&CenterDot;e^{j{\mathrm{\&phi;}}_n}(\frac{1}{64}\underset{i=0}{\overset{63}{\mathrm{\&Sigma;}}}{s}_{i-l}\&CenterDot;s_i^{*})+\frac{1}{64}\underset{i=0}{\overset{63}{\mathrm{\&Sigma;}}}{\mathrm{\&eta;}}_i\&CenterDot;s_i^{*}$

$={\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="H061E2927420061116E000061.png,H061E2927420061116E000131.png"\; state="\{\{state\}\}">h</figure-callout>}}_0\&CenterDot;e^{j{\mathrm{\&phi;}}_n}+{\tilde{N}}_s$

[equation 4]

$c_m^{\left(n\right)}=\frac{1}{128}{\left(r_m^{\left(n\right)}\right)}^T\&CenterDot;m^{*}={\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="H061E2927420061116E000061.png,H061E2927420061116E000131.png"\; state="\{\{state\}\}">h</figure-callout>}}_0+{\tilde{N}}_m$

If the autocorrelation value c that finds by equation 3 and equation 4 _s ⁽ⁿ⁾, c _m ⁽ⁿ⁾By standardization,, then generate equation 5 and equation 6 to remove the channel component that changes each subframe.

[equation 5]

${\tilde{c}}_s^{\left(n\right)}=\frac{c_s^{\left(n\right)}}{\left|c_s^{\left(n\right)}\right|}$

[equation 6]

${\tilde{c}}_m^{\left(n\right)}=\frac{c_m^{\left(n\right)}}{\left|c_m^{\left(n\right)}\right|}$

In this case, for c _s ⁽ⁿ⁾, c _m ⁽ⁿ⁾Standardization can be respectively by downlink synchronization code correlation detection module 11 and training sequence code correlation detection module 12, perhaps carry out by downlink synchronization code and training sequence code correlation detection module 13.As selection, for c _s ⁽ⁿ⁾, c _m ⁽ⁿ⁾Standardization can carry out by the independent standardized calculation unit (not shown in FIG.) that is provided between downlink synchronization code and training sequence code correlation detection module 13 and downlink synchronization code correlation detection module 11 and the training sequence code correlation detection module 12.

Downlink synchronization code and training sequence code correlation detection module 13 are searched c according to equation 7 _s ⁽ⁿ⁾, c _m ⁽ⁿ⁾Cross-correlation, to obtain in the downlink synchronization code of received signal and the phase shift between the training sequence code.

[equation 7]

$p_n={\left({\tilde{c}}_s^{\left(n\right)}\right)}^T\&CenterDot;{\left({\tilde{c}}_m^{\left(n\right)}\right)}^{*}=(e^{j{\mathrm{\&phi;}}_n}+{\tilde{N}}_s)\&CenterDot;(1+{\tilde{N}}_m^{*})$

$=e^{j{\mathrm{\&phi;}}_n}+e^{j{\mathrm{\&phi;}}_n}\&CenterDot;{\tilde{N}}_m^{*}+{\tilde{N}}_s+{\tilde{N}}_s\&CenterDot;{\tilde{N}}_m^{*}$

Suppose

With Be negligible very little value, it can calculate at the downlink synchronization code of received signal and the phase shift p between the training sequence code _n

According to above scheme, downlink synchronization code in being included in each subframe and the phase shift between the training sequence code are calculated by phase-detection unit 10, then inner product computing unit 20 are exported in the phase shift of calculating.

Fig. 5 is the more detailed block diagram of inner product computing unit 20.

With reference to figure 5, this inner product computing unit 20 is searched q=[q ₀..., q ₃] ^T=[1,1), (1,1), (1,1), (1,1)] ^TPlural inner product, it is the coordinate representation with the vector form of " quaternary phase place " S1 (135 °, 45 °, 225 °, 135 °), and P _n[P _n..., P _N+3] ^T, it is the vector representation of the phase shift of four continuous subframes being found by phase estimation unit 10.

If the inner product value that is found by inner product computing unit 20 is by standardization, it can obtain equation 8.

[equation 8]

$M_n=\frac{P_n^T\&CenterDot;q^{*}}{\sqrt{2}}$

This frame synchronization detecting unit 30 is carried out frame synchronization by inner product value that will calculate and the threshold ratio that presets.Judgement is described in detail as follows by the method for the threshold value that frame synchronization detecting unit 30 uses.

At first, it can consider to cause all situations of quaternary phase place S1 and S2.Because frame synchronization is unknown, supposes to exist S1 and S2, can be corresponding in the 14 kinds of total situations shown in the table 2 four continuous phase shifts being provided with many situations.

For example, there is the situation of " S2 " " S1+S2 " expression " S1 " back.And, the frame synchronization error of " skew " expression subframe unit in table 2.That is, " skew " is that it refers to first quaternary (quadruple) that four continuous quaternary phase places comprise second quaternary (quadruple) to " S2 " of " S1 " under 1 the situation in " S1+S2 ".

This is switched to the vector form coordinate with the phase place identical with each similar the former " q " composition with (1 ,-1), searches and standardization vector S 1 and plural inner product.If like this, can be provided in the value shown in the table 2.

[table 2]

Reference table 2, under the situation of " S1 ", the real part of this inner product has 4 The value of maximum.And the value of second maximum is

Therefore, it can be judged With 4

Between the random value that exists as a threshold value.Especially, because the level of received signal is variable according to noise and decline substantially, Can be judged as threshold value by Maximum Likelihood Detection.If the size of real part is equal to, or greater than

The S1 that it can be considered to receive.

In some cases, if there is the quaternary phase place that is different from quaternary phase place (phase quadruple) S1 or S2 in 3GPP TDD LCR system, it also can use the imaginary part of inner product to remove judgment threshold.

Simultaneously, if there is frequency shift (FS), then by quaternary phase place but, between downlink synchronization code and training sequence code, phase shift occurs by frequency shift (FS).Under the situation that the frequency shift (FS) that is activated as AFC (automatic frequency control) changed according to the time, the phase shift that detects can differently appear in each subframe.In this case, frequency shift (FS) refers to the difference on the frequency between the local oscillator of base station and UE, perhaps the difference on the frequency that is produced by the Doppler frequency effect in channel or the like.In addition, because frequency shift (FS) causes sampling error in UE, perhaps worsen receptivity significantly by adding up according to the time, this UE detects frequency shift (FS) by AFC and comes compensating frequency skew continuously.

Therefore, carry out under the situation of frame synchronization at frame synchronization detecting unit 30, preferred, the threshold value quilt is according to existence or do not exist the amount of frequency shift (FS) or frequency shift (FS) differently to be provided with, and/or the inner product value that calculates is by the comparison of the threshold value that differently is applied to and is provided with.

For example, if the frequency shift (FS) that is detected by UE less than reference value, can detect frame synchronization by the real part of the inner product value of first threshold and calculating relatively.If the frequency shift (FS) that detects is greater than this reference value, then can detect frame synchronization by the absolute value of the inner product value of second threshold value and calculating relatively.

Exist under the situation of frequency shift (FS), preferred, the absolute value of use inner product is because it can not utilize the real part of inner product value to judge the reception that exists or do not have S1 according to former method.This explains below in detail.

Reference table 2 is because the absolute value of inner product is 4 , under the sort of situation, S1 is received.Otherwise maximum is 4.The situation of similar use inner product real part, it can be incited somebody to action by Maximum Likelihood Detection

Be judged as a threshold value.Therefore, the absolute value for inner product is equal to, or greater than

Situation, it can be considered to S1 and be received.

But, exist under the situation of quaternary phase place S1 and S2 in similar 3GPP TDD LCR system, even and not the matching synchronously of S1, situation that can similar reception S1 produces the absolute value 4 of inner product

And, be under 4 the situation, at the absolute value of inner product because its possible errors ground of noise and decline judges that S1 is received.In this case, except the absolute value that uses inner product, it can be more accurately to use the just in time previous phase value p that receives _N-1, perhaps the mode of the phase value of quaternary (for example, the phase shift pn of first value) is judged the reception that exists or do not have S1.

Reference table 2 is for the situation that receives S1 with judge the received situation of S1 mistakenly, if the absolute value of inner product is 4

Perhaps 4, and if S1 do not match synchronously, the just in time previous quaternary phase place that receives and the quaternary phase place of current reception are explained as follows.(1) situation of reception S1

S1 is succeeded by the situation of S1: (135 °, 454 °, 225 °, 135 °), (135 °, 45 °, 225 °, 135 °)

S2 is succeeded by the situation of S1: (315 °, 225 °, 315 °, 45 °), (135 °, 45 °, 225 °, 135 °)

(2) the synchronous situation that does not match with S1

The situation of S1+S2 is offset 1:(225 °, and 315 °, 45 °, 135 °), (45 °, 225 °, 135 °, 315 °)

The situation of S2+S2 is offset 2:(315 °, and 45 °, 135 °, 45 °), (225 °, 135 °, 315 °, 225 °).

Under the received situation of S1, S1 or S2 may take place received in advance.In this case, at the phase value P that is just in time receiving _N-1Be worth P with first of quaternary before _nBetween phase shift be 0 ° or 90 °.On the other hand, under the synchronous unmatched situation of S1, corresponding phase shift is-90 ° or 180 °.If phase shift is expressed in the complex number plane shown in Figure 6, a zone that is used to judge the situation that receives S1 and does not receive the situation of S1 can be defined by the straight line that is expressed as y=-x.Therefore, exist or do not exist the judgement of S1 to carry out in the following manner.

[equation 9]

$M_n^{\&prime;}(p_{n-1},p_n)=\mathrm{Re}\left[p_n{p}_{n-1}^{*}\right]+\mathrm{Im}\left[p_n{p}_{n-1}^{*}\right]$

If equation 9 expression positive numbers, situation is that S1 is received.If equation 9 expression negatives, situation is that S1 does not match synchronously.

More than the frame synchronization estimating device according to one embodiment of the invention of Xie Shiing can be realized in subscriber equipment (UE).Simultaneously, if frequency shift (FS) by according to AFC to migration and provisionally (temporally) change.Then the phase shift of estimating in each subframe may differently be worsened.Preferably, by in the process of frame synchronization estimation, stopping frequency offset compensation function, can prevent that the phase shift of this estimation from differently being produced in each subframe according to AFC.

When frame synchronization detecting unit 30 was carried out frame synchronization, preferred, the threshold value quilt was according to the different setting of comparing with the inner product value that calculates of frequency shift (FS).Especially, UE detects frequency shift (FS).If the frequency shift (FS) that detects is less than reference value, then detect frame synchronization by the real part of the inner product value of first threshold and calculating relatively.If the frequency shift (FS) that detects is greater than reference value, then detect frame synchronization by the absolute value of the inner product value of second threshold value and calculating relatively.

Fig. 7 is the flow chart according to the execution initial synchronization method of another preferred embodiment of the present invention.

With reference to figure 7, the subframe that UE will receive from the base station is decomposed into a plurality of zones, searches correlation with 32 downlink synchronization codes for each of a plurality of zones, calculates then for each regional correlation peak (S71).This step is at length explained below.

At first, in 3GPP TDD LCR system, the SYNC-DL sign indicating number is used as downlink synchronization code, and they use the sequence of 32 types.In initial cell search procedure, UE is search DwPTS in the subframe shown in figure 2, and need not to be used for the information and the timing information of the sub-district that will search for.

Fig. 8 be example and the auto-correlation SYNC-DL sign indicating number and with the schematic diagram of the cross-correlation of another yard.In Fig. 8, peak point is corresponding to the part that has high correlation in received signal.

Usually, received signal { r}=(r ₀, r ₁...) received by mode on spreading rate with over-sampling.I SYNC-DL sign indicating number is represented as $\{S_{\left(l\right)}=(s_0^{\left(l\right)},s_1^{\left(l\right)},...,s_{63}^{\left(l\right)})\}.$ In this case, " 0≤1＜32 " are the QPSK code elements, and are the index of SYNC-DL sign indicating number.Correlation between received signal and i SYNC-DL sign indicating number can be by equation 10 definition.

[equation 10]

$c_i^{\left(l\right)}=|\underset{j=0}{\overset{63}{\mathrm{\&Sigma;}}}{r}_{i+j}^{*}\&CenterDot;s_j^{\left(l\right)}|$

Therefore, can find in each zone, to have the downlink synchronization code and the corresponding positional information of correlation peak by the Maximum Likelihood Detection of similar equation 11

[equation 11]

$c_{\hat{i}}^{\left(\hat{l}\right)}={\mathrm{<figure-callout\; id="0"\; label="max"\; filenames="H061E2927420061116E000061.png,H061E2927420061116E000131.png"\; state="\{\{state\}\}">max</figure-callout>}}_{0\&le;i<R}\left\{{\mathrm{<figure-callout\; id="0"\; label="max"\; filenames="H061E2927420061116E000061.png,H061E2927420061116E000131.png"\; state="\{\{state\}\}">max</figure-callout>}}_{0\&le;l<32}\right\{c_i^{\left(l\right)}\left\}\right\}$

In equation 11 and respectively expression have the SYNC-DL sign indicating number of correlation peak and in corresponding zone for value with correlation peak point detection.And, the size in " R " expression zone.Above step is repeated to search the maximum for each regional correlation in a subframe, and the index with peaked synchronous code and time point is shown in Figure 9.

Preferably, step S71 is repeated at least two subframes.For the subframe after second, obtain the correlation peak of each zone and each synchronous code, and then each zone is combined (S72) with each synchronous code mutually until the correlation peak of corresponding subframe.After the correlation peak addition of corresponding subframe and combining, it checks whether satisfy defined terms (S73) in each zone and each synchronous code.

If the difference between the value of the value of the maximum among the value that is produced by each zone of combination and correlation peak of each synchronous code and second maximum is equal to, or greater than the threshold value that presets, then satisfy defined terms.In other words, if maximum value or the value of second maximum are equal to, or greater than the threshold value that presets among the combined value of correlation peak, there is possibility hardly following the tracks of incorrect message context.And, need not to observe again several frames, on that time point, detect initial synchronisation (S76).In addition, it can only be only applicable to first subframe with defined terms.And it can skip this step S73.

If do not satisfy defined terms, then UE stores each zone and the combined value of each synchronous code until the correlation peak of corresponding subframe, has the synchronous code of each subframe and each regional correlation peak and the index (S74) of time point.

Subsequently, its number of checking the subframe whether be used to search each regional correlation peak is preset value H (S75).If the number of subframe is less than H, the step that begins from step S71 is repeated for next subframe.If the number of subframe and H match, use this value of storage so far to carry out initial synchronisation (S76).In this case, " H " can be selected in the scope of the accuracy that can guarantee initial synchronization detection.

Under the situation that receives the H subframe, the equation relevant with aforesaid correlation can be redefined and be equation 12 in the past.

[equation 12]

$c_{i,h}^{\left(l\right)}=\underset{j=0}{\overset{63}{\mathrm{\&Sigma;}}}{r}_{(i+\mathrm{hn}6400)+j}^{*}\&CenterDot;s_j^{\left(l\right)}$

In this case, suppose 0≤h＜H, 0≤i＜6400, and also received signal is by over-sampling n time.

Total correlation peak for H subframe in a zone can be defined as equation 13.

[equation 13]

$c_{\hat{i}}^{\left(\hat{l}\right)}=\underset{h=0}{\overset{H-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="0"\; label="max"\; filenames="H061E2927420061116E000061.png,H061E2927420061116E000131.png"\; state="\{\{state\}\}">max</figure-callout>}}_{0\&le;i<R}\left\{{\mathrm{<figure-callout\; id="0"\; label="max"\; filenames="H061E2927420061116E000061.png,H061E2927420061116E000131.png"\; state="\{\{state\}\}">max</figure-callout>}}_{0\&le;l<32}\right\{c_i^{\left(l\right)}\left\}\right\}$

If be satisfied in step S73 defined terms, if perhaps at the number of step S75 subframe corresponding to H, initial synchronisation is used the combined value estimation (S76) of the correlation peak in each zone and each synchronous code so far.In this case, it is estimated that initial synchronisation estimation refers to the index of the index of the downlink synchronization code that the sub-district that is arranged at UE uses and time synchronized point.

Index corresponding to peaked synchronous code among the combined value of each zone and the correlation peak of each synchronous code is selected as downlink synchronization code.The index of time synchronized point can be by the detection in the zone of a maximum value among corresponding to the combined value at correlation peak in many ways of following method.In addition, this time synchronized point also can be equally detects with other method.

In first method, the index of a time point is judged as the index of time synchronized point, and the correlation peak of the synchronous code of Xuan Zeing is exported in the peaked zone among corresponding to the combined value in correlation peaks at one the most continually thereon.Figure 10 is a schematic diagram of explaining first method.Because some i is the point exported the most continually in the peaked zone among corresponding to the combined value in correlation peaks of correlation peak thereon, this corresponding point is detected as the time synchronized point.

In second method, find the mean value of index of time point of the correlation peak of the synchronous code of selecting in the peaked zone among corresponding to combined value at correlation peak.Then, this mean value is selected as the index of time synchronized point.

In the 3rd method, give weighting by time point index to the correlation peak of the synchronous code selected in the peaked zone among corresponding to combined value at correlation peak, find the mean value of weighting.And this weighted average is judged as the index of this time synchronized point.

Figure 11 is the block diagram that is used to carry out the initial synchronisation device according to a preferred embodiment of the invention.Because the present invention relates to the initial synchronisation in the subscriber equipment of mobile communication, device shown in Figure 11 can be realized in subscriber equipment substantially.

With reference to Figure 11, a kind of device that is used to carry out initial synchronisation according to the preferred embodiments of the present invention comprises: at least one subframe that will receive from the base station is decomposed at least two zones, and calculate the correlation peak computing unit 71 of correlation peak at least by means of each the downlink synchronization code that is used for two zones, the correlation peak composite module 73 that correlation peak each is regional and each downlink synchronization code is combined, use the initial synchronization detection module 75 of the combined value execution initial synchronisation of correlation peak, with the combined value of each zone of storage and the correlation peak of each downlink synchronization code with have the memory module 77 of some index of the correlation peak of each zone and each downlink synchronization code.

Because the function of corresponding module explains in description above that its detailed explanation is omitted in the following description.And, become more convenient in the embodiment of the corresponding composition shown in Figure 11 combination by software, hardware or software and hardware.

Figure 12 is the figure for the analog result of the situation that exists in different channel shown in the table 3 and frequency shift (FS).

With reference to Figure 12, show the SYNC-DL sign indicating number detection error rate according to the SNR variation of different channels.The PA3 channel illustrates best performance, and the VA120 channel illustrates the worst performance.

[table 3]

Figure 13 A to 13D is similar table 3 according to the initial synchronisation histogram for the variation of the SNR of different channel (PA3, PB3, VA30, VA120) respectively.With reference to figure 13A to 13D, the situation of synchronous points is accurately found in " 0 " expression.And it judges that error is acceptable in 4 chips.Value in a chip-spaced is by the over-sampling unit representation."＜-4 " or " 4＜" expression synchronous points found beyond 4 chips, and it is judged as the situation of initial synchronization error.Therefore, can see, when SNR becomes low, the performance deterioration that becomes.

The initial estimation that detects is used as the reference synchronous points of time tracker, AFC (automatic frequency control) or AGC (automatic gain control) and frame synchronization, and it is important finding accurate initial synchronisation.

Therefore, the invention provides following effect or advantage.At first, because each regional correlation peak is the summation for several subframes, the correlation that storage reaches number of regions is enough.Therefore, compare with the method that is stored in all correlations in the subframe, the present invention can prevent that memory from increasing.Secondly, the present invention can be by means of the initial synchronisation that obtains to have high reliability less than the method for a correlation peak of frame store a to(for) subframe.

Apparent for those skilled in the art, need not to break away from spirit of the present invention or scope, can carry out various modifications and variations in the present invention.Therefore, this invention is intended to cover it improvement of the present invention and variation that is provided within appended claim and its equivalent scope is provided.

Claims (6)

1. method of carrying out downlink frame synchronization in the portable terminal of mobile communication system comprises step:

The phase-shift value of acquisition between downlink synchronization code and training sequence code, downlink synchronization code and training sequence code are included in each of M the subframe that links to each other receiving from the base station;

The plural inner product of calculating between the phase vectors of M phase-shift value of the reference vector of representing M reference phase value and expression acquisition;

Detection between base station and portable terminal frequency shift (FS) and

Use the plural inner product of calculating to carry out frame synchronization;

Wherein, if frequency shift (FS) is equal to or less than reference value, then frame synchronization is that real part and predetermined threshold ratio result according to the plural inner product of calculating carries out,

Wherein, if frequency shift (FS) greater than this reference value, then frame synchronization is to use the imaginary part of the plural inner product of calculating to carry out.

According to the process of claim 1 wherein if the real part of the plural inner product of calculating is equal to, or greater than this threshold value, then frame synchronization is to carry out under the phase-shift value of phase vectors and the phase value of reference vector are identical hypothesis.

3. according to the method for claim 1, further comprise step: use at downlink synchronization code and be included in phase shift between the training sequence code in the subframe that just in time before M continuous subframe, receives, and carry out frame synchronization at downlink synchronization code and the phase-shift value that is included between the training sequence code among of M continuous subframe.

4. device that is used for carrying out in mobile communication system frame synchronization comprises:

Phase detecting module, it obtains downlink synchronization code in being included in subframe and the phase-shift value between the training sequence code;

The inner product computing module, it calculates the plural inner product between the phase vectors of the reference vector of M reference phase value of expression and M phase-shift value of expression, and this M phase-shift value is for each acquisition of the individual continuous subframe of M by phase detecting module;

The frequency offset detection module, it detects the frequency shift (FS) between base station and portable terminal; With

The frame synchronization detection module, it uses the plural inner product of calculating to carry out this frame synchronization;

Wherein, if the frequency shift (FS) that detects is equal to or less than reference value, then real part and the predetermined threshold ratio result according to the plural inner product of calculating carries out frame synchronization;

Wherein, if frequency shift (FS) greater than this reference value, then uses the imaginary part of the plural inner product of calculating to carry out frame synchronization.

5. according to the device of claim 4,, then under being identical hypothesis, the phase-shift value of phase vectors and the phase value of reference vector carry out frame synchronization if wherein the real part of the plural inner product of Ji Suaning is equal to, or greater than this threshold value.

6. according to the device of claim 4, wherein the frame synchronization detection module uses the downlink synchronization code be included in the subframe that just in time received and the phase-shift value between the training sequence code before M continuous subframe, and is included in downlink synchronization code among of M continuous subframe and the phase-shift value between the training sequence code is carried out frame synchronization.

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