CN101425819B - Method and apparatus for time sequence control in channel estimation - Google Patents

Abstract

The invention relates to a time sequence control method and a device thereof used for channel estimation. Channel estimation windows are orderly moved by the method. After one of the channel estimation windows is moved, a metering value is calculated out according to a time-delay path and the channel frequency power of the channel estimation window, and the metering values of the other channel estimation windows are orderly calculated out. Then the maximum metering value is found out in the metering values, and the time sequence of the channel estimation is adjusted according to the position of the channel estimation window with the maximum metering value.

Description

Sequential control method in channel estimating and device

Technical field

The invention relates to a kind of method of sequencing control, and particularly relevant for a kind of sequential control method in channel estimating.

Background technology

In the environment of radio communication, because the caused Doppler effect of movement of receiving terminal or transmission end, or because electromagnetic wave is subject to the diffraction of barrier between receiving terminal and the transmission end and the multipath phenomenon that refraction causes, so that the received signal of receiving terminal is subject to a large amount of interference.With present code division multiple access (Code Division Multiple Access, being designated hereinafter simply as CDMA) system is example, since cdma system utilize a plurality of spreading codes (spreading code) at the same time between in transmit a plurality of users' signal, and utilize between each spreading codes orthogonality (orthogonal) so that the signal between the user can not interfere with each other.But when the signal that transmits is subjected to multipath when disturbing in transmission channel, and the orthogonality between the spreading codes is also with destroyed, thereby produces multiple user and disturb (Multiple-User Interference, MUI).

In order to promote the quality of transmission, cdma system has utilized the channel estimating technology to estimate the response that transmission channel at receiving terminal, and utilizes equalizer to eliminate the impact that transmission channel causes signal.Fig. 1 illustrates the system block diagram that utilizes the receiving terminal of equalizer for traditional cdma system.Please refer to Fig. 1, receiving signal r (t) estimates via channel estimation unit 110 and channel response, namely estimate the delay time T channel gain corresponding with each time of delay that each delay path in the channel, and channel estimation unit 110 is with channel gain

Export to equalizer 130.And equalizer 130 will utilize the channel gain that receives After eliminating the to received signal impact of r (t) of channel, see through again correlator 150 with spreading codes (spreadingcode) c[n of client] the reception signal frequently processed through equalizer 130 of the exhibition of separating, and utilize decision package 170 to demodulate digital signal

Yet, under the restriction of hardware, when the delay of multi-path channel diffusion (delay spread) is larger, may not consider every delay path in the channel in the channel estimation unit 110, as shown in Figure 2.Fig. 2 shows channel power and postpones profile (channel power delayprofile).Please refer to Fig. 2, abscissa is delay time T, ordinate be power (namely

6 delay path Path_1～Path_6 have been comprised among Fig. 2, and the time of delay and the power that represent respectively delay path Path_1～Path_6 with 6 pulses, in addition, one channel estimating window (Channel Estimation Window also is shown among Fig. 2, hereinafter to be referred as CEWindow), the channel length that can process when the represented CE Window length that goes out represents to carry out channel estimating at every turn among Fig. 2.As seen from Figure 2, the length of CE Window is less than the total length of delay path.Therefore, postpone all can't cover whole delay path Path_1～Path_6 in any case put CEWindow in the profile at channel power.

In present technology, CE Window has two kinds of disposing ways, first kind of way is as foundation with the gross power in the CE Window, namely allow CE Window put the position that can comprise maximum gross power, this gross power is the sum total that makes the channel power of every delay path of CE Window.The second way is the original position that directly original position of CE Window is arranged at frame, and namely article one arrives the delay path of receiving terminal, the position of putting such as CEWindow among Fig. 2.As seen from Figure 2, delay path P5 and P6 are not contained among the CE Window.In other words, in the situation of hardware constraints, CE Window can't cover every delay path in the channel, thereby causes channel estimating to estimate actual channel response, and then so that the usefulness of equalizer descend.Therefore, the putting of CE Window position will become a whether good pointer of channel estimating, and then becomes the key factor that affects the receiving terminal performance.

Yet, (for example U.S. Patent number 7 in present patent, 058,399 and the early stage publication number 2007/0009065 of United States Patent (USP)) in all only have explanation how to put multipath search engine (Multi-Path Searcher in the cdma system, MPS) window, but the suitable CE Window that puts how not inquired into.

Summary of the invention

The invention provides a kind of sequential control method in channel estimating, CEWindow can be put to suitable position, more complete channel response so that receiving terminal can be estimated, to improve the usefulness of receiving terminal.

The invention provides a kind of time sequence control device in channel estimating, in order to adjust the position of CEWindow, to improve the usefulness of receiving terminal.

The invention provides a kind of sequential control method in channel estimating, comprising: receive from launching and via the reception signal of channel the transmission end, and this channel has a plurality of delay paths; Search in the channel, time of delay corresponding to each delay path and corresponding channel power are to obtain channel power delay profile; One channel estimating window is provided; With interval one special time, the position of sequentially mobile channel estimation window in channel power delay profile is to obtain a plurality of candidate's sections; The quantity of the delay path that is captured in channel power postpones profile according to candidate's section and corresponding channel power calculate the corresponding variable of each candidate's section; In the corresponding variable of each candidate's section, find out the best section with maximum variable; And utilize best section, determine the sequential of channel estimating.

In one embodiment of the invention, the above-mentioned step that obtains those candidate's sections comprises: postpone the delay path of the leftmost side in the profile by channel power, mobile the left window sequentially is to obtain a plurality of left sides candidate's section; Postpone the delay path of the rightmost side in the profile by channel power, mobile right side window sequentially is to obtain a plurality of right sides candidate's section; And overlap or during original position right side in right side window of the original position of the left window when the left window and right side window, the left window and right side window stop mobile, and the set of these left side candidate's sections and these right sides candidate's section is above-mentioned candidate's section.

In one embodiment of the invention, the above-mentioned step that obtains those candidate's sections more comprises: record candidate section postpones the original position of profile at channel power, and wherein, the original position of i candidate's section is expressed as X _iRecord candidate section postpones the number of the delay path that comprises in the profile at channel power, and wherein, the delay path number that i candidate's section comprises is expressed as L _iAnd record candidate section postpones the gross power of the delay path that comprises in the profile at channel power, and wherein, the totalizing wattmeter of the delay path that i candidate's section comprises is shown P _i, its value is the summation of channel power corresponding to the delay path that comprises of i candidate's section.

In one embodiment of the invention, the above-mentioned step that obtains those candidate's sections also comprises: set up a form, and form comprises a plurality of fields, wherein, i candidate's section of i Related fields; And store i the original position X that candidate's section is corresponding _i, delay path number L _iAnd gross power P _iTo i field.

The step of the variable that in one embodiment of the invention, each candidate's section of above-mentioned calculating is corresponding comprises: according to i delay path number L that field is stored in the form _iAnd gross power P _i, calculate i the variable that candidate's section is corresponding, be expressed as M (X _i) and with i the variable M (X that candidate's section is corresponding _i) be stored to i field.Variable M (the X that above-mentioned i candidate's section is corresponding _i)=P _iβ (L _i), wherein, β (L _i) be L _iZooming parameter.And zooming parameter β (L _i) mathematical expression be:

$\mathrm{\β}\left(L_i\right)=\frac{{L_i}^{\mathrm{Li}}{e}^{-(\mathrm{Li}-1)}}{(L_i-1)!},$

After calculating variable corresponding to candidate's section, will be from all candidate's sections, find out have maximum variable candidate's section as a best section.

In one embodiment of the invention, original position corresponding to above-mentioned best section is expressed as X _Max, after the above-mentioned step of finding out best section, also comprise: a section last time is provided, this last time section be that last time the channel estimating window postpones the position of profile in channel power, wherein, last time the original position of section was expressed as X _PrevUtilize the original position of the stored candidate's section of form, in candidate's section, find out the original position X of the most approaching last time section _PrevA continuous section, wherein, continuously the original position of section is expressed as X _ContiAnd the variable that utilizes the stored candidate's section of form, judge the variable M (X that best section is corresponding _Max) and the continuous corresponding variable M of section (X _Conti) between difference whether less than a threshold value; If then determine with continuous section as a present section; If not, determine then that with best section as present section, wherein, the original position of this present section is expressed as X _Now

In one embodiment of the invention, after the above-mentioned step determining present section, also comprise: the original position X that judges present section _NowWith the original position X of section last time _PrevBetween difference whether less than a unit interval; If, then with the original position X of present section _NowChange to the last time original position X of section _PrevIf not, then keep the original position X of present section _NowAnd the channel estimating window moved to present section.

The present invention proposes a kind of time sequence control device in channel estimating in addition, comprises multipath search engine, computing unit and adjustment unit.Wherein, the multipath search engine hunts out time of delay corresponding to a plurality of delay paths in the transmission channel and corresponding channel power, postpones profile to obtain a channel power.Computing unit is with interval one special time, the position of in channel power delay profile, sequentially moving a channel estimating window, to obtain a plurality of candidate's sections, and the quantity of the delay path that in channel power postpones profile, is captured according to candidate's section and corresponding channel power, calculate the corresponding variable of each candidate's section.And adjustment unit is found out the best section with maximum variable in the corresponding variable of each candidate's section, and utilizes best section to determine the sequential of channel estimating.

In one embodiment of the invention, on be set forth in time sequence control device in the channel estimating, also comprise a storage element, in order to store a section last time, wherein, last time section represented that channel estimating window last time postponed position in the profile at channel power.

In one embodiment of the invention, after adjustment unit obtains best section, with calculating and the difference between the variable of its corresponding variable of the immediate candidate's section of section and best section last time, decide a present section.

In one embodiment of the present of invention, after this adjustment unit determines present section, to utilize present section to postpone original position and the difference between the original position of section in this channel power delay profile last time in the profile at channel power, adjust the original position of present section in channel power delay profile, and after adjustment, the channel estimating window is moved to present section.

Delay path and channel power that the present invention comprises because seeing through each candidate's section, calculate the variable of each candidate's section, and decide a best section according to variable, CE Window can be put to suitable position, so that can estimating, receiving terminal more complete channel response, to improve the usefulness of receiving terminal.

For above-mentioned feature and advantage of the present invention can be become apparent, preferred embodiment cited below particularly, and with reference to the accompanying drawings, make following detailed description.

Description of drawings

Fig. 1 shows the system block diagram that traditional cdma system utilizes the receiving terminal of equalizer.

Fig. 2 shows channel power and postpones profile.

Fig. 3 shows the receiving terminal system block diagram of the embodiment of the invention.

Fig. 4 shows the internal frame diagram of the channel estimation unit 310 of the embodiment of the invention.

Fig. 5 shows the internal frame diagram of the time sequence control device 380 of the embodiment of the invention.

Fig. 6 shows the schematic diagram of embodiment of the invention CE Window position movement.

Fig. 7 shows the flow chart of steps of the sequential control method in channel estimating of the embodiment of the invention.

The channel power that Fig. 8 shows channel model postpones profile.

Fig. 9 shows the position of CE Window and the tendency chart of bit error rate (BER).

Figure 10 shows the probability density function figure of its gross power under different delay path numbers.

Figure 11 shows the internal frame diagram of the time sequence control device 380 of another embodiment of the present invention.

Figure 12 shows the flow chart of steps of the sequential control method in channel estimating of another embodiment of the present invention.

Figure 13 shows each substep flow chart of the step S1230 of another embodiment of the present invention.

Figure 14 shows the left window W in another embodiment of the present invention _LState diagram with right side window WR.

Figure 15 shows the form of another embodiment of the present invention.

Figure 16 shows the tendency chart of bit error rate (BER) under different receiving terminal translational speeds.

[primary clustering symbol description]

110,310: channel estimation unit

130,330: equalizer

150: correlator

170,370: decision package

R (t): receive signal

Channel gain

Digital signal

C[n]: spreading codes

Path_1～Path_6: delay path

CE Window: channel estimating window

300: receiving terminal

350: separate Zhan Pin unit 350

380: time sequence control device

410_2～410_M: delay cell

430_1～430_M: correlator

450_1～450_M: multiplier

$\hat{h}\left(0\right),\hat{h}\left(1\right),\hat{h}\left(2\right),...,\hat{h}(M-1):$ Channel gain

b _P: frequency pilot sign

510,1110: the multipath search engine

530,1130: computing unit

550,1150: adjustment unit

D1, D2, D3, D4, D5, D6: candidate's section

S710～S760: each step of the sequential control method in channel estimating of the embodiment of the invention

1170: storage element

S1210～S1295: each step of the sequential control method in channel estimating of another embodiment of the present invention

Each substep of S1310～S1330: step S1230

W _L: the left window

W _R: right side window

S1, S2: simulation curve

Embodiment

For the channel estimating window can be put in position, obtain good channel estimating result, the present invention proposes one in channel estimating sequential control method and the time sequence control device in channel estimating.Embodiments of the invention for convenience of description below all use cdma system as example, still, those of ordinary skills should know by inference, the present invention also can be applicable to other Zhan Pin system, or the communication system of any use channel estimating, adjusts the position of channel estimating window.

Fig. 3 shows the receiving terminal system block diagram of the embodiment of the invention.Please refer to Fig. 3, receiving terminal 300 comprises channel estimation unit 310, equalizer 330, separates Zhan Pin unit 350, decision package 370 and time sequence control device 380.Receiving terminal 300 receives from transmitting terminal and via the reception signal r (t) of wireless transmission channel.Estimated by channel estimation unit 310 again and channel gain And the estimate channel response that inputed to equalizer 330.And equalizer 330 utilizes the channel gain that comes from channel estimation unit 310

Calculate equaliser weights (weight), and r (t) grade to received signal, to eliminate multi-path channel for the interference that receives signal r (t).In the present embodiment, equalizer 330 can use linearity to minimize mean square error (Liner MinimumMean-Square Error, LMMSE) algorithm or least square (Least Squares, LS) algorithm etc. can be used for the technology of the Adaptive signal processing of equalizer.This since equalizer techniques be not emphasis of the present invention, so give unnecessary details no longer in detail.

Then, separate Zhan Pin unit 350 and receive reception signal after processing via equalizer 330, and utilize spreading codes (spreading code) c[n of client] separate exhibition frequently after, allow decision package 370 demodulate digital signal

Under the condition of hardware constraints, when channel estimation unit 310 was carried out channel estimating at every turn, indefinite length ground was processed and is received signal r (t) simultaneously, obtains complete channel response.Therefore, channel estimation unit 310 has channel estimating window (the ChannelEstimation Window of a finite length, hereinafter to be referred as CE Window), and when carrying out channel estimating, can only capture the channel estimation value under the CE Window length at every turn.And time sequence control device 380 proposed by the invention can be adjusted the position of CE Window, so that channel estimation unit 310 can capture the weight that suitable channel comes the computation balance device.

The time sequence control device 380 that proposes of the embodiment of the invention for convenience of description, below hypothesis channel estimation unit 310 internal frame diagram as shown in Figure 4, but the present invention is not limited to the framework of this kind channel estimating.Please refer to Fig. 4, channel estimation unit 310 comprises a plurality of delay cell 410_2～410_M, a plurality of correlator 430_1～430 M and a plurality of multiplier 450_1～450_M.And channel estimation unit 310 mainly is frequency pilot sign (pilotsymbol) b that utilizes receiving terminal known _PCarry out channel estimating.

At first, receiving signal r (t) sequentially is delayed unit 410_2～410_M and postpones a time T _S, and original reception signal r (t) and the reception signal r (t-T that postpones _S), r (t-2T _S) ..., r (t-(M-1) T _S) input respectively correlator 430_1～430_M.Via correlator 430_1～430_M to received signal r (t) and the reception signal r (t-T that postpones _S), r (t-2T _S) ..., r (t-(M-1) T _S) solution is opened up frequently and after the sampling, recycling multiplier 450_1～450_M is respectively divided by frequency pilot sign b _P, remove the composition that receives signal in the signal, to obtain channel gain

In the present embodiment, suppose above-mentioned M=L * N, wherein, L is chip (chip) number that CE Window can cover, and N was sampling ratio (over-sampling ratio).Above-mentioned sample time T _S=T _C/ N, wherein, T _CBe the chip time (chipduration) of cdma system.And the CE Window length of present embodiment is T _C* L=T _S* M is in order to capture above-mentioned signal r (t-T _S), r (t-2T _S) ..., r (t-(M-1) T _S) carry out channel estimating.

The time sequence control device 380 that the embodiment of the invention proposes can be adjusted the sequential (timing) of CE Window, namely adjusts the signal that channel estimation unit 310 is carried out channel estimating.And the inside structure of time sequence control device 380 as shown in Figure 5.Please refer to Fig. 5, time sequence control device 380 comprises multipath search engine 510, computing unit 530 and adjustment unit 550.Wherein, multipath search engine 510 hunts out in the transmission channel every corresponding time of delay of delay path and channel power, postpones profile (channel power delay profile) to obtain a channel power.In the present embodiment, it for example is shown in Figure 2 that channel power postpones profile, and every corresponding channel power of delay path for example be every corresponding channel gain of delay path square.At this, time of delay and channel power can be that multipath search engine 510 observation transmission channels are after a period of time, with average delay time and the average channel power of channel circumstance gained after the variation of this section in the time averages.In addition, time of delay and channel power also can be instantaneous time of delay of channel and channel power.The embodiment of the invention for convenience of description, the time of delay of the following stated and channel power are all time of delay and the channel power after average.

Next, computing unit 530 will utilize the resulting channel powers of multipath search engine 510 to postpone profiles, with interval one special time, postpone in the profile the sequentially position of mobile CE Window at channel power, to obtain a plurality of candidate's sections.In the present embodiment, above-mentioned special time can be the chip time T _C, sample time T _SOr the time of other systemic presupposition.In addition, CE Window also can be with time of delay of each delay path as mobile foundation, namely with the interval of time of delay of delay path as special time.Take Fig. 2 as example, this channel power postpones profile can comprise two candidate's sections, the original position of first candidate's section for example is corresponding time of delay of delay path Path_1, and the original position of second candidate's section for example is corresponding time of delay of delay path Path_2.And the mode that above-mentioned CE Window moves can be to be moved right gradually by the earliest delay path Path_1, until surpass delay path Path_6 the latest.In addition, the mode that CE Window moves also can be moved to the left gradually by delay path Path_6 the latest, until surpass delay path Path_1 the earliest.

In the present embodiment, suppose that the special time that above-mentioned CE Window moves the institute interval is T sample time _S, and CE Window is moved right gradually by the earliest delay path P1, until surpass delay path P6 the latest.Fig. 6 illustrates the schematic diagram into embodiment of the invention CE Window position movement.Please refer to Fig. 6, CE Window is with T sample time _SSequentially move right, obtain a plurality of candidate's section D1, D2 and D3.

Please also refer to Fig. 5 and Fig. 6, after computing unit 530 obtains candidate's section D1, D2 and D3, postpone the quantity of in profile corresponding delay path and corresponding channel power with D3 at channel power according to candidate's section D1, D2, calculate each candidate's section D1, D2 and the corresponding variable of D3.For the fluency of present embodiment explanation, comparatively in the content of back, the computational methods of the corresponding variable of each candidate's section will be described at present embodiment.

Next, adjustment unit 550 will be in candidate's section D1, D2 and D3, find out have maximum variable candidate's section as a best section, and utilize this best section to determine the sequential of channel estimation unit 310.For instance, have maximum variable if adjustment unit 550 is found out candidate's section D2, and with candidate's section D2 as the best section of putting CE Window, then channel estimation unit 310 postpones T backward with the reception signal that will capture _SThat is to say that the signal transition that channel estimation unit 310 is carried out channel estimating is r (t-T _S), r (t-2T _S), r (t-3T _S) ..., r (t-MT _S).

Although above-described embodiment is directly as the position of CE Window with best section, but those of ordinary skills should know by inference, the present invention also can be position with best section as the reference position, come mobile channel to estimate the putting position of employed CE Window.In addition, the CE Window in above-described embodiment has a regular length, but when practical application was of the present invention, the length of CE Window can adjust according to the actual channel situation, and therefore, the present invention does not limit the length of CE Window.

In present cdma system, the most normal use harrow type receiver (Rake receiver).And comprise a plurality of rake pins (finger) in the harrow type receiver, be used for respectively collecting in the channel signal on every delay path, and separate the signal that exhibition receives frequently.For the harrow type receiver of arranging in pairs or groups, cdma system uses a multipath search engine (Multi-Path Searcher, MPS) at present, hunts out average channel power and postpones profile, and upgrade channel power delay profile at every certain interval of time.And harrow type receiver will utilize the resulting result of multipath search engine, suitably dispose the delayed reception signal that each rake pin receives.

Multipath search engine 510 in above-described embodiment can utilize in the present cdma system multipath search engine to implement.That is to say, the time sequence control device 380 of present embodiment can be after traditional multipath search engine upgrades channel power delay profile, allow computing unit 530 recomputate the variable of each candidate's section, and again find out best section, to upgrade at any time the position of CE Window according to the actual state of channel.Yet, although the time sequence control device 380 in above-described embodiment utilizes the multipath search engine in the cdma system, but, those of ordinary skills can know by inference, as long as can hunt out time of delay of every delay path of channel and the time sequence control device that channel power just can be applied to present embodiment, so the present invention is not limited to above-mentioned application mode.

By the operation of the time sequence control device 380 in above-described embodiment with channel estimation unit 310, can summarize a kind of sequential control method in channel estimating, as shown in Figure 7.Fig. 7 shows the flow chart of steps of the sequential control method in channel estimating of the embodiment of the invention.Please also refer to Fig. 3, Fig. 4, Fig. 5 and Fig. 7, at first, the reception signal r (t) (step S710) that receiving terminal 300 receives from a channel.Next, multipath search engine 510 hunts out in the channel, time of delay corresponding to every delay path and corresponding channel power, postpones profile (step S720) to obtain a channel power.Then, computing unit 530 is with interval one special time, and sequentially mobile CE Window postpones position in the profile at channel power, to obtain a plurality of candidate's sections (step S730).The number of the delay path that computing unit 530 is captured in channel power postpones profile according to candidate's section again and corresponding channel power calculate variable corresponding to each candidate's section (step S740).Then, adjustment unit 550 is found out the best section (step S750) with maximum variable in variable corresponding to each candidate's section.At last, adjustment unit 550 utilizes best section, determine the sequential (step S760) of channel estimating, namely determine the CE Window position of channel estimation unit 310, to adjust the reception signal that is captured when channel estimation unit 310 is carried out channel estimating at every turn.

In explanation before how present embodiment to obtain variable corresponding to candidate's section, illustrate that in advance delay path quantity that CE Window comprises is for the impact of receiving terminal usefulness.Cook up in advance a channel model at this, as shown in Figure 8.The channel power that Fig. 8 illustrates channel model postpones profile.Please refer to Fig. 8, this abscissa is time of delay, and each time interval one chip time T _CIts ordinate (not illustrating) is the power of delay path.Channel model among Fig. 8 comprises 6 delay path P1～P6.Wherein, delay path P2～P6 has identical power, and the power of delay path P1 is greater than the power of delay path P2～P6.In addition, the corresponding abscissa of delay path P1 is 0, with the benchmark as time of delay.

Next, the inventor utilizes the mode of Computer Simulation, simulates the channel model of receiving terminal system and above-mentioned Fig. 8, and sequentially the usefulness of receiving terminal is observed in the position of mobile CE Window.Fig. 9 shows the position of CE Window and the tendency chart of bit error rate (BER) (Bit Error Rate is hereinafter to be referred as BER).Please refer to Fig. 8, its abscissa is the original position of CE Window, and ordinate is bit error rate (BER).And in this simulation, CE Window length is 16 chip time T _C, and begun to move right for-2 position by abscissa.Three simulation curves are arranged among Fig. 9, the simulated conditions of article one simulation curve (take the circular curve that represents with straight line) be the power of delay path P1 as 1, the power of delay path P2～P6 is all 0.1.The simulated conditions of second simulation curve (curve that represents take triangle and straight line) as the power of delay path P1 as 1, the power of delay path P2～P6 is all 0.2.Article three, the simulated conditions of simulation curve (curve that represents with straight line take square) as the power of delay path P1 as 1, the power of delay path P2～P6 is all 0.4.

In the second simulation curve of Fig. 9, the power of delay path P2～P6 sum total just equals the power of delay path P1.But can be found out by the second simulation curve, move to 8T in the original position of CE Window _CAfterwards, CE Window has only comprised delay path P2～P6, and the BER of this moment is significantly less than the BER when only covering delay path P1.Even in article one simulation curve in Fig. 9, the power of delay path P2～P6 sum total is 0.5, only has half of delay path P1 power.But the BER when CE Window has comprised delay path P2～P6 still is significantly less than the BER when only covering delay path P1.In addition, by the 3rd simulation curve among Fig. 9 as can be known, when the power of the delay path that comprises as CE Window was larger, BER also can be less.

Comprehensive above-mentioned simulation result, the energy of the delay path power that CE Window comprises and the delay path quantity that comprises all can affect the usefulness of receiving terminal significantly.The delay path power that the account form of the variable that therefore, candidate's section is corresponding must comprise with candidate's section and the quantity of delay path are relevant.

Implement the present invention for the instruction that makes those of ordinary skills can see through embodiment, present embodiment proposes the account form of a variable, and is as follows:

M(X _i)＝P _i·β(L _i) (1)。

In above-mentioned (1) formula, X _iThe position of expression candidate section, M (X _i) variable corresponding to expression candidate's section, P _iThe gross power of the delay path that expression CE Window comprises, L _iExpression position X _iThe delay path number that comprises of candidate's section, β (L _i) in the present embodiment in order to as L _iZooming parameter, its mathematical expression is as follows:

$\mathrm{\β}\left(L_i\right)=p\left({\stackrel{\‾}{\mathrm{\γ}}}_L\right)/p\left({\stackrel{\‾}{\mathrm{\γ}}}_1\right)---\left(2\right).$

In above-mentioned (2) formula,

With

Be respectively

With

Probability density number (probability density function is hereinafter to be referred as pdf).

Be expressed as the average signal noise ratio (Signal to Noise Ratio is hereinafter to be referred as SNR) of L bar delay path,

Be expressed as the average signal noise ratio of 1 delay path.Because in multi-path channel, every delay path is similar to and is subject to Rayleigh decline (Rayleigh fading), that is to say, the probability density function of the SNR of every delay path is all rayleigh distributed (Rayleigh distribution), and the SNR of L bar delay path to carry out maximum ratio be p (γ in conjunction with the probability density function after (Maximal Ratio Combining, MRC) _L).Figure 10 illustrates and is the probability density function figure under different delay path numbers.Illustrate respectively the probability density function p (γ of L=1～6 among Figure 10 _L).Gone out by Figure 10 observable, work as γ _L=1 o'clock, p (γ _L) value increase and increase along with L.

In above-mentioned (2) formula, suppose the probability density function p (γ of the SNR of every delay path ₁) be all rayleigh distributed, and hypothesis γ _L=1.Therefore, above-mentioned (2) formula can be expressed as:

$\mathrm{\β}\left(L_i\right)=p\left({\stackrel{\‾}{\mathrm{\γ}}}_L\right)/p\left({\stackrel{\‾}{\mathrm{\γ}}}_1\right)$

$=\frac{{L_i}^{\mathrm{Li}}{e}^{-(\mathrm{Li}-1)}}{(L_i-1)!}---\left(3\right).$

Can find out β (L by above-mentioned (3) formula _i) be the strictly increasing function of L.Therefore, by above-mentioned (1) formula as can be known, the variable M (X of candidate's section of present embodiment _i) for example be the delay path gross power P that utilizes candidate's section to comprise _iAnd the number L of delay path _iZooming parameter β (the L that obtains _i) decide.That is to say that if two candidate's sections that gross power is identical are arranged simultaneously, in the present embodiment, the candidate's section with more delay path number can obtain larger variable.

In addition, can be pushed away β (1)=1, β (2)=1.4715, β (3)=1.827, β (4)=2.1242, β (5)=2.3848, β (6)=2.6197 by the definition of above-mentioned (3) formula β (L) ...By the distribution of above-mentioned β (L) as can be known, the β that present embodiment proposes (L) function is not a linear function, when L increases, the amplitude that this function increases is but more and more less, that is to say, when the path number that candidate's section comprises was excessive, what the delay path number can be not complete was reflected in the variable.Angle with physics, because the variation of each delay path instantaneous amplitude in the channel, cause many delay paths to disappear mutually and the result who grows mutually, so that when receiving terminal is considered a plurality of delay paths (namely when CE Window cover mulitpath) simultaneously, the signal that receiving terminal receives is not easy to be subject to the degree of depth decline (deep fading) of channel, and then so that the usefulness raising of receiving terminal.This is namely when CE Window covers mulitpath, so that the reason that receiving terminal usefulness increases.

But, the effect that can reach with long mutually result is limited because many delay path instantaneous amplitudes disappear mutually, when the delay path of therefore considering when receiving terminal arrived a given number, the delay path number that CEWindow comprises increased, and the effect that receiving terminal usefulness is increased also diminishes.So when β (L) function in the variable that present embodiment proposes increased along with delay path number L, the amplitude that the functional value of β (L) increases was but more and more less, and then so that the amplitude of variable increase diminish.

In order to reduce the operand of receiving terminal, above-mentioned computing unit 530 can store the functional value of β (L) and the corresponding relation of delay path number L in advance.In the process of above-mentioned calculated candidate sector value, as long as computing unit 530 is learnt the delay path number that comprises in candidate's section, just can directly utilize stored corresponding relation, obtain the functional value of β (L).And the corresponding relation of the functional value of β (L) and delay path number L can be stored in above-mentioned computing unit 530 through the mode of form.In addition, the β of above-mentioned (3) formula gained (L) function is that the SNR of every delay path of hypothesis is rayleigh distributed.But those of ordinary skills should know that actual channel circumstance may not be considered as rayleigh distributed, therefore, can design β (L) function according to channel circumstance and the systems organization of reality.

In the above-described embodiments, the variable account form of candidate's section for example is that direct gross power and β (L) function with delay path multiplies each other and get.But those of ordinary skills should know by inference, and the variable of candidate's section also can be to utilize respectively the gain of each the bar delay path in candidate's section or the power of each bar channel to come as the foundation of calculating variable.In other words, so long as utilize the number of the power of the delay path that candidate's section comprises or channel gain and delay path as the foundation of variable, just belonged to scope of the present invention.

In the above-described embodiments, can improve the usefulness of receiving terminal although utilize the position of mobile CE window, but in the process of mobile CE window position, because the position that CE window moves is excessive, may not arrive reception signal partly so that receiving terminal has to process, thereby cause the problem of receiving terminal Missing data.In order to prevent that above-mentioned problem from producing, the present invention has also introduced a mechanism that prevents that CE window position from beating, and is applied among the ensuing embodiment, below just begins to illustrate another embodiment of the present invention.

Present embodiment suppose that below present embodiment is applied to cdma system, and the system block diagram of hypothesis receiving terminal as shown in Figure 3 for convenience of description.In the present embodiment, except time sequence control device 380, remaining each member function is all same as the previously described embodiments, so give unnecessary details no longer in detail in the receiving terminal 300.Figure 11 illustrates the internal frame diagram of the time sequence control device 380 of another embodiment of the present invention.Please refer to Figure 11, time sequence control device 380 comprises multipath search engine 1110, computing unit 1130, adjustment unit 1150 and storage element 1170.Wherein, multipath search engine 1110, computing unit 1130 all are similar to the embodiment of Fig. 5 with the function of adjustment unit 1150, so repeat no more.

By above-described embodiment as can be known, each multipath search engine 1110 upgrades channel power to postpone after the profile, adjustment unit 1130 all can be readjusted the position of CEWindow in the channel estimation unit 310, comes the sequential of the reception signal r (t) that control channel estimation unit 310 captures.But when adjustment unit 1130 moves the position of CE window when excessive, may be so that receiving terminal have been omitted the reception signal of part, thereby cause the problem of receiving terminal Missing data.In order to prevent above-mentioned problem, present embodiment is used last time section of a storage element 1170 storages one, this last time section for example be to upgrade before channel powers postpone profiles at multipath search engine 1110, CE window postpones the position of profile at channel power.And, adjustment unit 1150 in the present embodiment has one and adjusts mechanism, utilize stored last time section, avoid the position of the mobile CE window of non-essential, and then prevent the excessive problem that causes in CEwindow shift position in the channel estimation unit 310.Below just in the mode of flow chart, the flow chart of the sequential control method in channel estimating that present embodiment proposes is described.

Figure 12 shows the flow chart of steps of the sequential control method in channel estimating of another embodiment of the present invention.Please also refer to Fig. 3, Fig. 4, Figure 11 and Figure 12, at first, the reception signal r (t) (step S1210) that receiving terminal 300 receives from a channel.Next, multipath search engine 1110 hunts out in the transmission channel every corresponding time of delay of delay path and channel power, postpones profile (step S1220) to obtain a channel power.It for example is shown in Figure 2 that this channel power postpones profile.

Next, computing unit 1130 utilizes multipath search engine 1110 resulting channel powers to postpone profile, with interval one special time, postpone in the profile the sequentially position of mobile CE Window at channel power, to obtain a plurality of candidate's sections (step S1230).Wherein, this special time for example is the time of delay at delay path interval.

Hunt out the speed of candidate's section in order to increase computing unit 1130, present embodiment is in the process of searching candidate's section, and CE Window for example is divided into a left window, and (following table is shown W _L) (following table is shown W with a right side window _R), and computing unit 1130 mobile the left window W simultaneously _LWith right side window W _R, search candidate's section.Therefore, above-mentioned steps S1230 more comprises a plurality of substeps, as shown in figure 13.In addition, Figure 14 illustrates and is the left window W in another embodiment of the present invention _LWith right side window W _RMobile state diagram.Please also refer to Figure 13 and Figure 14, after computing unit 1130 obtained channel power delay profile, computing unit 1130 was with the left window W _LThe delay path that is postponed the leftmost side in the profile by channel power begins to move, to obtain a plurality of left side candidate's sections (step S1310).Then, computing unit 1130 is with right side window W _RThe delay path that is postponed the rightmost side in the profile by channel power begins to move, to obtain a plurality of right side candidate's sections (step S1320).

The first state by Figure 14 (namely begins mobile the left window W _LWith right side window W _RInitial condition) can find out the left window W _LBegin mobile position in the time of delay of Path_1, and obtain left side candidate's section D1.In addition, right side window W _RBegin mobile position in the time of delay of Path_6, and obtain right side candidate's section D2.The second state by Figure 14 can be found out, the left window W _L, move to the time of delay of Path_2, and obtain left side candidate's section D3 as mobile foundation with the interval between the adjacent delay path.The second state by Figure 14 can be found out right side window W _R, move to the time of delay of Path_5, and obtain right side candidate's section D4 as mobile foundation with the interval between the adjacent delay path.Next, as the left window W _LWith right side window W _ROverlap or the left window W _LOriginal position at right side window W _RThe original position right side time, computing unit 1130 stops mobile the left window W _LWith right side window W _R(step S1330), in other words, as the left window W _LResulting left side candidate's section and right side window W _RWhen the delay path that resulting right side candidate's section comprises repeats, the left window W _LWith right side window W _RTo stop to move, and the candidate window that repeats will be deleted.The third state by Figure 14 can be found out, the left window W _LMove to the time of delay of Path_3 the time of delay by Path_2, and obtain left side candidate's section D5.And right side window W _RBy the time of delay that moves to Path_4 time of delay of Path_5.But, this moment right side window W _ROriginal position surpassed the left window W _LOriginal position, therefore, right side window W _RRight side candidate's section D6 of gained is with deleted.At last, by the left window W _LResulting left side candidate's section is D1, D3 and D5, by right side window W _RResulting right side candidate's section is D2 and D4, and whole candidate's sections is the set of left side candidate's section D1, D3, D5 and right side candidate's section D2, D4, namely D1, D2, D3, D4 and D5.Move foundation such as above-mentioned mode take the interval between the adjacent delay path as window, can obtain minimum and for all possible candidate's section, therefore can reduce the required form of storage candidate's section.

Please later with reference to Figure 11 and Figure 12, after obtaining candidate's section, computing unit 1130 will according to the delay path number that captured of candidate's section in channel power delay profile and corresponding channel power, calculate the variable (step S1240) of each candidate's section.And the method for calculating variable for example be above-mentioned (1) and (3) formula.In above-mentioned steps S1230 and S1240, computing unit 1130 can just directly calculate its variable when obtaining candidate's section, can be after obtaining whole candidate's sections, just to calculate variable corresponding to each candidate's section.In addition, computing unit 1130 also can be set up a form, and the candidate regions section of gained is positioned at channel power postpones original position, gross power, the path number of profile and the variable that calculates is recorded in this form, and this form for example is shown in Figure 15.In the foregoing embodiments, computing unit 1130 is found out five candidate's section D1, D2, D3, D4 and D5, so has original position, gross power, path number and variable that five fields record respectively five candidate's section D1, D2, D3, D4 and D5 among Figure 15.

After step S1240, adjustment unit 1150 is found out the candidate's section with maximum variable, and with this candidate's section as the best section (step S1245) of putting CE Window.Because present embodiment is beated for fear of unnecessary CE Window, the Missing data that causes when preventing CE Window to move, therefore, after determining best section, present embodiment also adds following step.At this, for convenient following explanation, best section is expressed as X in the original position that channel power postpones in the profile _Max, and $X_{\max }={\max }_{X_i}\left\{M\left(X_i\right)\right\},$ Wherein, i=1～5.

Next, adjustment unit 1150 reads out the position (step S1250) of the last time section in the storage element 1170, and at this, last time the original position of section was expressed as X _PrevNext, utilize stored original position (X in the form among above-mentioned Figure 15 ₁～X ₅), find out a continuous section (step S1260) of the original position of the most approaching last time section, at this, the original position of section is expressed as X continuously _Conti, and $X_{\mathrm{conti}}={\max }_{X_i}\left\{\right|X_i-X_{\mathrm{prev}}\left|\right\}.$

Then, utilize the stored variable of Fig. 5 form, adjustment unit 1150 is judged variable M (X corresponding to best section _Max) and the continuous corresponding variable M of section (X _Conti) between difference whether less than a threshold value (threshold), namely judge M (X _Max)-M (X _ContiWhether)＜threshold is true (step S1265).If judge M (X _Max)-M (X _Conti)＜threshold, then be illustrated in upgrade channel power and postpone profile after, the corresponding variable in position and the corresponding variable difference of best section of the most approaching last time CE Window are very little.Therefore, adjustment unit 1150 will be with continuous section as present section (step S1270), and continues next step.If judge M (X _Max)-M (X _Conti) 〉=threshold, after then being illustrated in renewal channel power delay profile, the corresponding variable in position and the corresponding variable of best section of the most approaching last time CE Window are widely different, therefore, adjustment unit 1150 will determine with best section as present section (step S1275).At this, the original position of section is expressed as X at present _Now

After determining present section, adjustment unit 1150 will be judged the original position X of present section again _NowWith the original position X of section last time _PrevBetween difference whether less than a unit interval (step S1280), in the present embodiment, the unit interval for example is a chip time T _C, and above-mentioned steps S1280 will judge | X _Now-X _Prev|＜T _CWhether be true.If judge | X _Now-X _Prev|＜T _C, then adjustment unit 1150 is with the original position X of present section _NowBe adjusted into the last time original position X of section _Prev(step S1285) namely allows X _Now=X _PrevIn other words, because the original position X of the present section that adjustment unit 1150 determines _NowWith the original position X of section last time _PrevGap is less than a chip time T _C, therefore, adjustment unit 1150 does not need CE Window position in the mobile channel estimation unit 310.On the contrary, if judge | X _Now-X _Prev| 〉=T _C, then adjustment unit 1150 will be kept the original position X of present section _Now(step S1290).At last, the present section that adjustment unit 1150 utilization determines is adjusted the sequential (step S1295) of channel estimating, determines that namely channel estimation unit 310 carries out the signal that channel estimating captures at every turn.In the present embodiment, adjustment unit 1150 X that can for example directly use step S1285 or S1290 to determine _Now, allow channel estimation unit 310 carry out the signal of channel estimating by r (t) originally, r (t-T _S), r (t-2T _S) ..., r (t-(M-1) T _S) change r (t-X into _Now), r (t-X _Now-T _S), r (t-X _Now-2T _S) ..., r (t-X _Now+ (M-1) T _S).

Below come emulation receiving terminal usefulness in the mode of software, and the hypothesis transmission channel channel be the channel model of Fig. 8.Figure 16 is illustrated in the tendency chart of bit error rate (BER) under the different receiving terminal translational speeds.Please refer to Figure 16, its abscissa is translational speed, and unit is kilometer/hour that ordinate is bit error rate (BER) BER.Comprise two simulation curve S1 and S2 among Figure 16, wherein curve S 1 in the known technology with the position that the comprises maximum power simulation curve as CE Window putting position, and the simulation curve of the method that curve S 2 proposes for above-described embodiment.As seen from Figure 16, no matter in the situation that curve S 1 is very fast in translational speed or translational speed is slower, its bit error rate (BER) BER all is inferior to curve S 2.That is to say, use the receiving terminal of putting CE Window method proposed by the invention, though be channel be fast-fading (fast fading) or at a slow speed the decline (slow fading) situation under, can both obtain than the better usefulness of the receiving terminal of known technology.

In sum, the present invention can summarize following advantage:

1. the present invention adjusts the sequential of channel estimating because of delay path and channel power in the foundation CE Window.Allow receiving terminal under the condition of hardware constraints, can also allow CE Window put to suitable position, more complete channel response so that channel estimation unit can be estimated, to improve the usefulness of receiving terminal.

2. in the variable computational methods that the embodiment of the invention proposes, see through a zooming parameter β (L _i), between the number of upper delay path and the variable and non-linear relation, thereby so that the size of variable more can dope CE Window position exactly on the impact of receiving terminal usefulness.

3. the present invention sees through one and adjusts mechanism, when the sequential of each adjustment channel estimating, can avoid the position of the mobile CE window of non-essential, or the frequency of adjusting CE window position is too high, and then so that in the process of adjusting CE window, can prevent the excessive problem that causes in CE window shift position.

Although the present invention discloses as above with preferred embodiment; so it is not to limit the present invention; those of ordinary skill in the technical field under any; without departing from the spirit and scope of the present invention; the a little change of Ying Kezuo and correction, so protection scope of the present invention should be with being as the criterion that claim limits.

Claims (15)

1. sequential control method in channel estimating comprises:

Reception receives signal from the transmission end via one of a channel, and wherein, this channel has a plurality of delay paths;

Hunt out in the described channel, time of delay corresponding to each described delay path and corresponding channel power, postpone profile to obtain a channel power;

One channel estimating window is provided;

With interval one special time, sequentially move the position of this channel estimating window in this channel power delay profile, to obtain a plurality of candidate's sections;

The quantity of described a plurality of delay paths that the described a plurality of candidate's sections of foundation are captured in described channel power delay profile and corresponding channel power calculate the corresponding variable of each described candidate's section;

In corresponding this variable of each described candidate's section, find out the best section with maximum variable; And

Utilize this best section, determine the sequential of described channel estimating.

2. the sequential control method in channel estimating as claimed in claim 1, wherein said channel estimating window comprises a left window and a right side window, above-mentioned with the described special time in interval, sequentially move the position of described channel estimating window in described channel power delay profile, to obtain the step of described candidate's section, comprise the following steps:

Delay path by the leftmost side in the described channel power delay profile sequentially moves described the left window, to obtain a plurality of left sides candidate's section;

Delay path by the rightmost side in the described channel power delay profile sequentially moves described right side window, to obtain a plurality of right sides candidate's section; And

When described the left window and described right side window overlap or during original position right side in described right side window of the original position of described the left window, described the left window and described right side window stop mobile, and the set of described a plurality of left sides candidate's section and described a plurality of right sides candidate's section is described a plurality of candidate's section.

3. the sequential control method in channel estimating as claimed in claim 1, wherein with the described special time in interval, sequentially the position of mobile described channel estimating window in described channel power delay profile to obtain the step of described a plurality of candidate's sections, more comprises the following steps:

Record described a plurality of candidate's section and postpone the original position of profile at described channel power, wherein, the original position of i candidate's section is expressed as X _iAnd

Record described a plurality of candidate's section and postpone the number of described a plurality of delay paths of comprising in the profile at described channel power, wherein, the delay path number that i candidate's section comprises is expressed as L _i

4. the sequential control method in channel estimating as claimed in claim 3 more comprises the following steps:

Record described a plurality of candidate's section and postpone the gross power of described a plurality of delay paths of comprising in profile at this channel power, wherein, the totalizing wattmeter of the delay path that i candidate's section comprises is shown P _i, its value is the summation of channel power corresponding to described a plurality of delay paths of comprising of i candidate's section.

5. the sequential control method in channel estimating as claimed in claim 4 more comprises the following steps:

Set up a form, this form comprises a plurality of fields, wherein, and i candidate's section of i Related fields; And

Store i the original position X that candidate's section is corresponding _i, delay path number L _iAnd gross power P _iTo i field.

6. the sequential control method in channel estimating as claimed in claim 5, wherein postpone the quantity of described a plurality of delay paths of being captured in the profile and corresponding channel power according to described a plurality of candidate's sections at described channel power, calculate the step of the corresponding described variable of each described candidate's section, comprise the following steps:

According to i delay path number L that field is stored in the described form _iAnd gross power P _i, calculate i the described variable that candidate's section is corresponding, be expressed as M (X _i); And

With i the described variable M (X that candidate's section is corresponding _i) be stored to i field.

7. the sequential control method in channel estimating as claimed in claim 6, original position corresponding to wherein said best section is expressed as X _Max, and after the above-mentioned step of finding out described best section, more comprise the following steps:

One section last time is provided, this last time section be that last time described channel estimating window postpones the position of profile in described channel power, wherein, the original position of described last time section is expressed as X _Prev

Utilize the original position of the stored described a plurality of candidate's sections of described form, in described a plurality of candidate's sections, find out the original position X near described last time section _PrevA continuous section, wherein, the original position of this continuous section is expressed as X _ContiAnd

Utilize the variable of the stored described a plurality of candidate's sections of described form, judge the variable M (X that described best section is corresponding _Max) and the corresponding variable M of described continuous section (X _Conti) between difference whether less than a threshold value; If then determine with described continuous section as a present section; If not, determine then that with described best section as described present section, wherein, the original position of described present section is expressed as X _Now

8. the sequential control method in channel estimating as claimed in claim 7 wherein after the step that determines described present section, more comprises the following steps:

Judge the original position X of described present section _NowOriginal position X with described last time section _PrevBetween difference whether less than a unit interval; If, then with the original position X of described present section _NowChange to the original position X of described last time section _PrevIf not, then keep the original position X of described present section _Now

9. the sequential control method in channel estimating as claimed in claim 8 wherein utilizes described best section, determines the step of the sequential of described channel estimating, comprises the following steps:

Described channel estimating window is moved to described present section.

10. the sequential control method in channel estimating as claimed in claim 1, in wherein said a plurality of candidate's sections, i candidate's section is expressed as X in the original position that described channel power postpones profile _i, i candidate's section is expressed as L in the delay path number that described channel power postpones to comprise in the profile _i, i candidate's section is shown P at the totalizing wattmeter that described channel power postpones the delay path that comprises in the profile _i, i variable corresponding to candidate's section is expressed as M (X _i), its value is M (X _i)=P _iβ (L _i), wherein, β (L _i) be L _iZooming parameter.

11. the sequential control method in channel estimating as claimed in claim 10, wherein above-mentioned zooming parameter β (L _i) mathematical expression be:

$\mathrm{\β}\left(L_i\right)=\frac{{L_i}^L{e}^{-(L_i-1)}}{(L_i-1)!}.$

12. the time sequence control device in channel estimating comprises:

One multipath search engine in order to hunt out time of delay corresponding to a plurality of delay paths in the transmission channel and corresponding channel power, postpones profile to obtain a channel power;

One computing unit, with interval one special time, the position of in described channel power delay profile, sequentially moving a channel estimating window, to obtain a plurality of candidate's sections, and postpone the quantity of described a plurality of delay paths of being captured in the profile and corresponding channel power according to described a plurality of candidate's sections at described channel power, calculate the corresponding variable of each described candidate's section; And

One adjustment unit in order in the corresponding described variable of each described candidate's section, is found out the best section with maximum variable, and is utilized this best section, determines the sequential of described channel estimating.

13. the time sequence control device in channel estimating as claimed in claim 12 more comprises:

One storage element, in order to store last time section, wherein, described last time section represents the last time position of described channel estimating window in described channel power delay profile.

14. the time sequence control device in channel estimating as claimed in claim 13, wherein after described adjustment unit obtains described best section, with calculating and utilizing near the difference between the variable of the corresponding variable of candidate's section of described last time section and described best section, decide a present section.

15. the time sequence control device in channel estimating as claimed in claim 14, wherein after described adjustment unit determines described present section, to utilize described present section to postpone difference between original position and the original position of described last time section in described channel power delay profile in the profile at described channel power, adjust the original position of described present section in described channel power delay profile, and after adjustment, described channel estimating window is moved to described present section.

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