CN103188189A - Measuring method and measuring device for channel time delay - Google Patents

Abstract

The invention relates to a measuring method and a measuring device for channel time delay. The method comprises the steps that frequency domain channel response is extracted from a plurality of subcarriers of a channel; whether positions of the subcarriers are positions where reference signals are located is judged; if the positions of the subcarriers are the positions where the reference signals are located, the corresponding frequency domain channel response is extracted from channel estimation directly, and merged; if the positions of the subcarriers are not the positions where the reference signals are located, whether the subcarriers are subcarriers in system bandwidth is judged; if the subcarriers are the subcarriers in the system bandwidth, the frequency domain channel response at the reference signals closest to the subcarriers is approximated, and merged; and if the subcarriers are not the subcarriers in the system bandwidth, the frequency domain channel response at the reference signals at the two ends of the system bandwidth is utilized to conduct linear interpolation. Therefore, the measuring method and the measuring device can better estimate the multipath channel time delay.

Description

Channel delay method of measurement and device

Technical field

The present invention relates to mobile communication system, especially relate to channel delay method of measurement and device in the mobile communication system.

Background technology

In various mobile communication system, channel estimating information has bigger influence for receptivity, and the latency measurement value of multipath channel has bigger influence to the channel estimation value of multipath channel.Therefore if can accurately estimate the time delay value of multipath channel, then can make channel estimation value more accurate, thereby promote receiver performance.System is example with Long Term Evolution (LTE), the LTE down channel is estimated the normal LMMSE of employing (Linear Minimum Mean Square Error estimation, the linear least mean-square difference is estimated) algorithm, its basic thought is: earlier with LS (Least Square, least square method) algorithm estimates the channel estimation value at LTE descending pilot frequency place, utilize MMSE (Minimum Mean Square Error respectively at frequency domain and time domain then, Minimum Mean Square Error) algorithm carries out the interpolation of frequency domain and time domain, obtains the channel estimation value at the non-pilot tone of LTE down channel place.Need utilize the cross correlation of each sub-carrier channels on the frequency domain when frequency domain MMSE interpolation, the cross-correlation information of each sub-carrier channels then is to calculate according to multipath channel latency measurement value.Therefore in the LTE down channel is estimated, if can estimate the channel delay value of multipath channel more accurately, then can obtain the cross-correlation information of each sub-carrier channels more accurately, and then estimate the channel estimation value of multipath channel more accurately.

In the LTE system, carry out channel estimating for the ease of terminal, all inserted a certain amount of reference signal (RS) in each subframe.Each reference signal corresponding an OFDM (Orthogonal Frequency Division Multiplexing, OFDM) symbol and a subcarrier.Concerning each residential quarter, reference signal is that (user terminal can go out the channel response of reference signal place correspondence according to the reference signal place data estimation that receives to user terminal for User Equipment, UE) known definite signal.Utilize the channel estimation value at reference signal place to do time-frequency conversion, obtain the channel time domain impulse response, can obtain the time delay value of multipath channel according to the channel time domain impulse response.The reception signal that present disclosed simple multipath channel time-delay measuring method also all is based on the reference signal place carries out.

Fig. 1 is the schematic diagram that reference signal distributes among the LTE.Be to simplify, the time orientation length (during general cyclic prefix (CP)) of a subframe of only having drawn among Fig. 1, frequency domain direction 12 subcarriers that only drawn, and only represented reference signal distribution situation on the transmitting antenna port.Dash area is represented the position at reference signal place among the figure, in the actual conditions different cell reference signals is had different side-play amounts at frequency domain, different transmitting antenna ports is had different distributions, but the relative position between each reference signal substantially to figure in similar, what all adopt is this discrete reference signal location mode.Simultaneously owing in the LTE system, generally adopt fast Fourier transform (FFT) and carry out time-frequency conversion, so the length of FFT greater than the number of actual sub-carriers, these non-existent subcarriers are empty subcarrier, do not have data also not have reference signal at empty subcarrier.

Owing to have empty subcarrier in the LTE system, do not contain any reference signal on the empty subcarrier, thereby receiving terminal do not known any channel information of empty subcarrier.When the frequency domain impulse response that utilizes the reference signal channel recovers the time domain impulse response of channel, because empty subcarrier place does not have the frequency domain impulse response of reference signal, so can cause the inaccurate and energy of channel time domain impulse response to leak.In existing method, the processing to empty subcarrier when extracting domain channel response is to utilize the channel response at RS place in two ends in the system bandwidth to do on average.Though this reveals energy certain inhibitory action is arranged, but still the time domain impulse response that can cause bigger energy to leak to make channel is inaccurate, causes the time delay error that records bigger, thereby influence receiver performance.

The problems referred to above in the LTE system also are present in other ofdm systems or MIMO (the multiple-input and multiple-output)-ofdm system.

Summary of the invention

Technical problem to be solved by this invention provides channel delay method of measurement and the device in a kind of mobile communication system, to estimate the latency measurement value of channel more accurately.

The present invention is that to solve the problems of the technologies described above the technical scheme that adopts be a kind of channel delay method of measurement, may further comprise the steps: the domain channel response that obtains reference signal place channel; Extract domain channel response from a plurality of subcarriers of channel; Judge whether sub-carrier positions is the reference signal position; If sub-carrier positions is the reference signal position, then directly from channel estimating, extracts corresponding domain channel response and merge; If sub-carrier positions is not the reference signal position, judge then whether this subcarrier is the interior subcarrier of system bandwidth; If it is this subcarrier is the subcarrier in the system bandwidth, approximate and merge with the reference signal place domain channel response nearest apart from this subcarrier; If this subcarrier is not the subcarrier in the system bandwidth, utilizes the domain channel response at reference signal place, system bandwidth two ends to carry out linear interpolation and obtain; Obtain the domain channel response of extraction; Domain channel response is done invert fast fourier transformation, to obtain the time domain channel impulse response; Calculate the tap power of time domain channel impulse response; According to the right tap thresholding of tap power calculation sending and receiving antenna; And the right channel delay of definite sending and receiving antenna.

In one embodiment of this invention, be to use least-squares algorithm to estimate the domain channel response of reference signal place channel.

In one embodiment of this invention, the step of extracting domain channel response from a plurality of subcarriers of channel comprises, extracts frequency domain response every several subcarriers.

In one embodiment of this invention, the step of determining the channel delay that the sending and receiving antenna is right comprises: determine the time delay expansion that the sending and receiving antenna is right respectively at each time slot; And the right time delay of each antenna estimated to average.

In one embodiment of this invention, said method is to carry out in containing the ofdm system receiver of empty subcarrier.

In one embodiment of this invention, said method is to carry out in the long evolving system receiver.

The present invention also proposes a kind of channel delay measurement mechanism, comprising: the device that is used for the domain channel response of acquisition reference signal place channel; Be used for extracting from a plurality of subcarriers of channel the device of domain channel response; Be used for judging whether sub-carrier positions is the device of reference signal position; If being used for sub-carrier positions is the reference signal position, then directly from channel estimating, extract corresponding domain channel response and the device that merges; If being used for sub-carrier positions is not the reference signal position, judge then whether this subcarrier is the device of the subcarrier in the system bandwidth; If be used for this subcarrier and be the subcarrier in the system bandwidth, and the device that merge approximate with the reference signal place domain channel response nearest apart from this subcarrier; If be used for this subcarrier and be not the subcarrier in the system bandwidth, utilize the domain channel response at reference signal place, system bandwidth two ends to carry out the device that linear interpolation obtains; The device that is used for the domain channel response of acquisition extraction; Be used for domain channel response is done invert fast fourier transformation, to obtain the device of time domain channel impulse response; The device that is used for the tap power of calculating time domain channel impulse response; Be used for the device according to the right tap thresholding of tap power calculation sending and receiving antenna; And the device that is used for the right channel delay of definite sending and receiving antenna.

Technical scheme of the present invention is when extracting channel frequency domain impulse response, if be empty subcarrier, then utilizing in the system bandwidth channel response at reference signal place, two ends to do linear interpolation obtains, this helps to reduce the error of empty subcarrier place channel frequency domain response value and actual channel frequency domain response value, and empty subcarrier and non-empty subcarrier adjacent do not have discontinuous saltus step simultaneously.Can more effectively reduce the energy amount of leakage when transforming to time domain from frequency domain like this, improve the accuracy of time domain channel impulse response, and then estimate the multipath channel time delay better, improve accuracy of channel estimation, receiver performance is got a promotion.

Description of drawings

For above-mentioned purpose of the present invention, feature and advantage can be become apparent, below in conjunction with accompanying drawing the specific embodiment of the present invention is elaborated, wherein:

Fig. 1 illustrates reference signal distribution schematic diagram in the LTE system.

Fig. 2 illustrates the channel delay method of measurement flow chart of one embodiment of the invention.

Fig. 3 illustrates the device schematic diagram in order to the channel delay method of measurement of carrying out one embodiment of the invention.

Fig. 4-Fig. 6 illustrates the channel delay measurement performance contrast of adopting the embodiment of the invention and existing scheme.

Fig. 7 illustrates the receiver performance contrast of adopting the embodiment of the invention and existing scheme.

Embodiment

Following embodiment of the present invention describes the channel delay method of measurement, and this method is applicable to various OFDMs (OFDM) system and multi-input multi-output-orthogonal frequency division multiplexing (MIMO-OFDM) system, for example Long Term Evolution (LTE) system.This method can be carried out in containing the ofdm system receiver of empty subcarrier, to estimate the time delay value of multipath channel more accurately.

Concerning receiver, because the transmission signal of reference signal position is known, be assumed to be

If the frequency domain channel impulse response of each reference signal position is expressed as

Then:

${\hat{H}}_{\mathrm{LS}}^{(r,p)}=\frac{{\tilde{r}}_{k^{\′},l^{\′}}^{(r,p)}}{x_{k^{\′},l^{\′}}^{(r,p)}},$

Wherein r ∈ 0,1}, p ∈ 0,1}, r are the reception antenna port, and p is the transmitting antenna port,

Frequency domain reception data for the reference signal position.

Fig. 2 illustrates the channel delay method of measurement flow chart of one embodiment of the invention.With reference to shown in Figure 2, this flow process is described below:

Step 201, the domain channel response that obtains reference signal place channel is estimated.

For example, can use LS (least square) algorithm to estimate according to reference signal, obtain domain channel response

Step 202 is extracted domain channel response from a plurality of subcarriers of channel.At this, from the length N of receiver FFT, several (for example Δ N) individual sub-carrier extract domain channel response of every interval

In step 203, judge whether the sub-carrier positions of extracting is reference signal RS position.If the sub-carrier positions of extracting is the position at reference signal place, then as step 205, directly from channel estimating (as

R ∈ 0,1}, p ∈ 0, extract corresponding domain channel response in 1}) and merge.

If the subcarrier that extracts is not in the reference signal position, then further judge that in step 204 whether this subcarrier is the subcarrier in the system bandwidth, if this subcarrier is the subcarrier in the system bandwidth, it is approximate and merge with the reference signal place domain channel response nearest apart from this subcarrier then to enter step 206.

If the subcarrier that extracts is empty subcarrier (being the subcarrier in the nonsystematic bandwidth), then utilizes the domain channel response at reference signal place, system bandwidth two ends to carry out linear interpolation in step 207 and obtain.

Thereby, at the channel frequency domain impulse response of step 208 extraction.It is exemplified as:

$h_{\mathrm{est},l_{\mathrm{RS}}^{\left(p\right)},i}^{(r,p)}=\left\{\begin{array}{cc}\frac{1}{2}\underset{l^{\&prime;}\&Element;\{l_{\mathrm{RS}}^{\left(p\right)},l_{\mathrm{RS}}^{\left(p\right)}+2\}}{\mathrm{\&Sigma;}}{\hat{h}}_{\mathrm{LS},l^{\&prime;},k_i}^{\&prime;(r,p)}& \mathrm{if}{l}_{\mathrm{RS}}^{\left(p\right)}+2<{\tilde{L}}_{\mathrm{RS}}^{\left(p\right)},0\&le;k_i\&le;2N_{\mathrm{RB}}^{\mathrm{DL}}-1\\ {\hat{h}}_{\mathrm{LS},l_{\mathrm{RS}}^{\left(p\right)},k_i}^{\&prime;(r,p)}& \mathrm{if}{l}_{\mathrm{RS}}^{\left(p\right)}+2\&GreaterEqual;{\tilde{L}}_{\mathrm{RS}}^{\left(p\right)},0\&le;k_i\&le;2N_{\mathrm{RB}}^{\mathrm{DL}}-1\\ \frac{1}{2}\underset{l^{\&prime;}\&Element;\{l_{\mathrm{RS}}^{\left(p\right)},l_{\mathrm{RS}}^{\left(p\right)}+1\}}{\mathrm{\&Sigma;}}({\mathrm{\&alpha;}}_{\mathrm{\&tau;},i}\&CenterDot;{\hat{h}}_{\mathrm{LS},l^{\&prime;},0}^{\&prime;(r,p)}+(1-{\mathrm{\&alpha;}}_{\mathrm{\&tau;},i})\&CenterDot;{\hat{h}}_{\mathrm{LS},l^{\&prime;},2N_{\mathrm{RB}}^{\mathrm{DL}}-1}^{\&prime;(r,p)})& \mathrm{if}{l}_{\mathrm{RS}}^{\left(p\right)}+2<{\tilde{L}}_{\mathrm{RS}}^{\left(p\right)},k_i\&GreaterEqual;2N_{\mathrm{RB}}^{\mathrm{DL}}\\ {\mathrm{\&alpha;}}_{\mathrm{\&tau;},i}\&CenterDot;{\hat{h}}_{\mathrm{LS},l_{\mathrm{RS}}^{\left(p\right)},0}^{\&prime;(r,p)}+(1-{\mathrm{\&alpha;}}_{\mathrm{\&tau;},i})\&CenterDot;{\hat{h}}_{\mathrm{LS},l_{\mathrm{RS}}^{\left(p\right)},2N_{\mathrm{RB}}^{\mathrm{DL}}-1}^{\&prime;(r,p)}& \mathrm{if}{l}_{\mathrm{RS}}^{\left(p\right)}+2\&GreaterEqual;{\tilde{L}}_{\mathrm{RS}}^{\left(p\right)},k_i\&GreaterEqual;2N_{\mathrm{RB}}^{\mathrm{DL}}\end{array}\right.$

${\mathrm{\&alpha;}}_{\mathrm{\&tau;}}=\frac{i\&CenterDot;\mathrm{\&Delta;N}-(12N_{\mathrm{RB}}^{\mathrm{DL}}-1)}{N-12N_{\mathrm{RB}}^{\mathrm{DL}}}$

k _i＝round(i·ΔN/6)

$L_{\mathrm{est}}^{\left(p\right)}=({\tilde{L}}_{\mathrm{RS}}^{\left(p\right)}\&GreaterEqual;2?2:1)$

$l_{\mathrm{RS}}^{\left(p\right)}=0,...,L_{\mathrm{est}}^{\left(p\right)}-1$

Each the meaning of parameters mark that relates in the above-mentioned expression formula is as follows:

Transmitting antenna port 0 or 1 OFDM symbol numbers in subframe;

The OFDM symbol numbers that latency measurement uses;

The OFDM symbol number that latency measurement uses;

k _i: transmitting antenna port 0 or 1 the numbering of parameter signal on frequency domain in the bandwidth;

α _τ: linear interpolation coefficient;

System bandwidth RB number;

R, p: finger is received antenna and transmitting antenna port respectively.

In step 209, domain channel response is done invert fast fourier transformation (IDFT), obtain the time domain channel impulse response.

For example right Do the IDFT conversion, obtain the time domain channel impulse response:

$H_{\mathrm{cir}}^{(r,p)}=[h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)}=0}^{(r,p)},...,h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)}=L_{\mathrm{est}}^{\left(p\right)}-1}^{(r,p)}],$

Wherein:

$h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)}}^{(r,p)}=\mathrm{IDFT}\left(h_{\mathrm{est},l_{\mathrm{RS}}^{\left(p\right)}}^{(r,p)}\right)=\mathrm{IDFT}\left({[h_{\mathrm{est},l_{\mathrm{RS}}^{\left(p\right)},i=0}^{(r,p)},h_{\mathrm{est},l_{\mathrm{RS}}^{\left(p\right)},i=1}^{(r,p)},...,h_{\mathrm{est},l_{\mathrm{RS}}^{\left(p\right)},i=N/\mathrm{\&Delta;N}-1}^{(r,p)}]}^T\right)$

$={[h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)},i=0}^{(r,p)},h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)},i=1}^{(r,p)},...,h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)},i=N/\mathrm{\&Delta;N}-1}^{(r,p)}]}^T$

In step 210, calculate the tap power of time domain channel impulse response.

Time domain channel impulse response h for example _CirTap power pow be:

${\mathrm{pow}}_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)}}^{(r,p)}={[{\left|h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)},i=0}^{(r,p)}\right|}^2,{\left|h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)},i=1}^{(r,p)}\right|}^2,...,{\left|h_{\mathrm{cir},l_{\mathrm{RS}}^{\left(p\right)},i=N/\mathrm{\&Delta;N}-1}^{(r,p)}\right|}^2]}^T$

In step 211, according to the right tap thresholding of tap power calculation sending and receiving antenna.At this, the sending and receiving antenna is to (r, tap thresholding p) is

To determine the channel delay that the sending and receiving antenna is right in step 212 and step 213.

In step 212, determine the time delay expansion that the sending and receiving antenna is right respectively at each time slot.

For example antenna is to (r, time delay expansion p)

For:

${\mathrm{\&tau;}}_{\max ,l_{\mathrm{RS}}^{\left(p\right)}}^{(r,p)}=\mathrm{\&tau;}{1}_{\max ,l_{\mathrm{RS}}^{\left(p\right)}}^{(r,p)}-{\mathrm{\&tau;}2}_{\max ,l_{\mathrm{RS}}^{\left(p\right)}}^{(r,p)},$

Wherein

Expression is greater than the tap thresholding

Maximum diameter,

Expression greater than the tap thresholding greater than the tap thresholding

Path.

Antenna is to (r, time delay spread estimation p) is that this antenna is to the mean value of last all time delay estimated values, that is:

${\mathrm{\&tau;}}_{\max }^{(r,p)}=\frac{1}{L_{\mathrm{est}}^{\left(p\right)}}\underset{l_{\mathrm{RS}}^{\left(p\right)}=0}{\overset{L_{\mathrm{est}}^{\left(p\right)}-1}{\mathrm{\&Sigma;}}}{\mathrm{\&tau;}}_{\max ,l_{\mathrm{RS}}^{\left(p\right)}}^{(r,p)}$

In step 213, to each antenna to (r, p) time delay is estimated to average.

Specifically, average to the time delay expanding value of determining to each sending and receiving antenna, final time delay spread estimation value is:

Fig. 3 illustrates the device schematic diagram in order to the channel delay method of measurement of carrying out one embodiment of the invention.In Fig. 3, baseband processing chip 300 is in the receiver, and comprises pilot tone place channel estimation module 310 and timing time delay estimation module 320.Pilot tone place channel estimation module 310 can estimate the domain channel response of reference signal place channel according to reference signal, for example uses LS to estimate to obtain domain channel response

Offer regularly time delay estimation module 320 then.Regularly time delay estimation module 320 can be carried out the step 201-213 in the flow process shown in Figure 2, finally to obtain channel delay after obtaining domain channel response.At this, pilot tone place channel estimation module 310, timing time delay estimation module 320 can be embodied as hardware, software or its combination.For example, pilot tone place channel estimation module 310, timing time delay estimation module 320 typically are embodied as the module of having solidified in order to the program code of carrying out above-mentioned steps.

Owing to do not contain pilot tone in the empty subcarrier, can not directly obtain the domain channel response at empty subcarrier place.If think that directly empty subcarrier place frequency domain channel is zero, then the error with empty subcarrier actual frequency domain channel response is bigger, and empty subcarrier and non-empty subcarrier adjacent have discontinuous saltus step simultaneously, will bring bigger energy to reveal like this.The above embodiment of the present invention has adopted following processing when extracting channel frequency domain impulse response: if empty subcarrier, then utilizing in the system bandwidth channel response at RS place, two ends to do linear interpolation obtains, this helps to reduce the error of empty subcarrier place channel frequency domain response value and actual channel frequency domain response value, and empty subcarrier and non-empty subcarrier adjacent do not have discontinuous saltus step simultaneously.Can more effectively reduce the energy amount of leakage when transforming to time domain from frequency domain like this, improve the accuracy of time domain channel impulse response, and then estimate the multipath channel time delay better, improve accuracy of channel estimation, receiver performance is got a promotion.

Provide the performance comparison of embodiments of the invention and existing method below with accompanying drawing.V0503 old is existing method among Fig. 4-Fig. 6, and V0503 LineInsert is the method that embodiments of the invention adopt, and Ideal EPA is the true time delay value of channel.As seen from the figure the present invention than the latency measurement value of existing scheme more near the true time delay value of channel.

Fig. 7 is the contrast of the receiver performance of employing embodiments of the invention and existing scheme, and wherein PS LI is for adopting the performance of receiver of the present invention, and Orignal is the performance of existing scheme receiver.After adopting embodiments of the invention as seen from Figure 7, because the latency measurement value is more accurate than existing scheme, thereby the performance of the receiver of the embodiment of the invention is also good than the performance that has the scheme receiver now.

Though the present invention discloses as above with preferred embodiment; right its is not in order to limiting the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; when can doing a little modification and perfect, so protection scope of the present invention is when with being as the criterion that claims were defined.

Claims (11)

1. channel delay method of measurement may further comprise the steps:

Obtain the domain channel response of reference signal place channel;

Extract domain channel response from a plurality of subcarriers of channel;

Judge whether sub-carrier positions is the reference signal position;

If sub-carrier positions is the reference signal position, then directly from channel estimating, extracts corresponding domain channel response and merge;

If sub-carrier positions is not the reference signal position, judge then whether this subcarrier is the interior subcarrier of system bandwidth;

If it is this subcarrier is the subcarrier in the system bandwidth, approximate and merge with the reference signal place domain channel response nearest apart from this subcarrier;

If this subcarrier is not the subcarrier in the system bandwidth, utilizes the domain channel response at reference signal place, system bandwidth two ends to carry out linear interpolation and obtain;

Obtain the domain channel response of extraction;

Domain channel response is done invert fast fourier transformation, to obtain the time domain channel impulse response;

Calculate the tap power of time domain channel impulse response;

According to the right tap thresholding of tap power calculation sending and receiving antenna; And

Determine the channel delay that the sending and receiving antenna is right.

2. the method for claim 1 is characterized in that, uses least-squares algorithm to estimate the domain channel response of reference signal place channel.

3. the method for claim 1 is characterized in that, the step of extracting domain channel response from a plurality of subcarriers of channel comprises, extracts frequency domain response every several subcarriers.

4. the method for claim 1 is characterized in that, determines that the step of the channel delay that the sending and receiving antenna is right comprises:

Determine the time delay expansion that the sending and receiving antenna is right respectively at each time slot; And

The right time delay of each antenna is estimated to average.

5. the method for claim 1 is characterized in that, is to carry out in containing the ofdm system receiver of empty subcarrier.

6. the method for claim 1 is characterized in that, is to carry out in the long evolving system receiver.

7. channel delay measurement mechanism comprises:

The device that is used for the domain channel response of acquisition reference signal place channel;

Be used for extracting from a plurality of subcarriers of channel the device of domain channel response;

Be used for judging whether sub-carrier positions is the device of reference signal position;

If being used for sub-carrier positions is the reference signal position, then directly from channel estimating, extract corresponding domain channel response and the device that merges;

If being used for sub-carrier positions is not the reference signal position, judge then whether this subcarrier is the device of the subcarrier in the system bandwidth;

If be used for this subcarrier and be the subcarrier in the system bandwidth, and the device that merge approximate with the reference signal place domain channel response nearest apart from this subcarrier;

If be used for this subcarrier and be not the subcarrier in the system bandwidth, utilize the domain channel response at reference signal place, system bandwidth two ends to carry out the device that linear interpolation obtains;

The device that is used for the domain channel response of acquisition extraction;

Be used for domain channel response is done invert fast fourier transformation, to obtain the device of time domain channel impulse response;

The device that is used for the tap power of calculating time domain channel impulse response;

Be used for the device according to the right tap thresholding of tap power calculation sending and receiving antenna; And

The device that is used for the right channel delay of definite sending and receiving antenna.

8. device as claimed in claim 7 is characterized in that, described is to extract frequency domain response every several subcarriers for the device that extracts domain channel response from a plurality of subcarriers of channel.

9. device as claimed in claim 7 is characterized in that, described device for the right channel delay of definite sending and receiving antenna further comprises:

Be used for determining respectively at each time slot the device of the time delay expansion that the sending and receiving antenna is right; And

Be used for the device that right time delay estimation averages to each antenna.

10. device as claimed in claim 7 is characterized in that, is included in the ofdm system receiver that contains empty subcarrier.

11. device as claimed in claim 7 is characterized in that, is included in the long evolving system receiver.

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