CN103188189B - Channel delay method of measurement and device - Google Patents

Abstract

The present invention relates to a kind of channel delay method of measurement and device.In the method, extract domain channel response from multiple subcarriers of channel, and judge whether sub-carrier positions is reference signal position; If sub-carrier positions is reference signal position, then directly from channel estimating, extracts corresponding domain channel response and merge; If sub-carrier positions is not reference signal position, then judge that whether this subcarrier is the subcarrier in system bandwidth; If this subcarrier is the subcarrier in system bandwidth, is similar to the reference signal place domain channel response nearest apart from this subcarrier and merges; If this subcarrier is not the subcarrier in system bandwidth, the domain channel response at reference signal place, system bandwidth two ends is utilized to carry out linear interpolation.Thus the present invention can estimate multipath channel time delays better.

Description

Channel delay method of measurement and device

Technical field

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

Background technology

In various mobile communication system, channel-estimation information has larger impact for receptivity, and the channel estimation value of the delay measurements of multipath channel on multipath channel has larger impact.If the time delay value of multipath channel therefore can accurately be estimated, then channel estimation value can be made more accurate, thus promote receiver performance.For Long Term Evolution (LTE) system, LTE down channel is estimated often to adopt LMMSE (LinearMinimumMeanSquareErrorestimation, linear minimum mean square error is estimated) algorithm, its basic thought is: first use LS (LeastSquare, least square method) algorithm estimates the channel estimation value at LTE descending pilot frequency place, then MMSE (MinimumMeanSquareError is utilized respectively at frequency-domain and time-domain, Minimum Mean Square Error) algorithm carries out the interpolation of frequency-domain and time-domain, obtains the channel estimation value at LTE down channel non-pilot place.Need to utilize the cross correlation of each sub-carrier channels on frequency domain when frequency domain MMSE interpolation, the cross-correlation information of each sub-carrier channels is then calculate according to multipath channel time delays measured value.Therefore, in LTE down channel is estimated, if the channel delay value of multipath channel can be estimated 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 LTE system, carry out channel estimating for the ease of terminal, all insert a certain amount of reference signal (RS) in each subframe.Corresponding OFDM (OrthogonalFrequencyDivisionMultiplexing, the OFDM) symbol of each reference signal and a subcarrier.Concerning each community, reference signal is the determination signal that user terminal (UserEquipment, UE) is known, and user terminal can go out channel response corresponding to reference signal place according to the reference signal place data estimation received.Utilize the channel estimation value at reference signal place to do time-frequency conversion, obtain channel time domain impulse response, the time delay value of multipath channel can be obtained according to channel time domain impulse response.At present disclosed simple multipath channel time delays method of measurement is also all carry out based on the Received signal strength at reference signal place.

Fig. 1 is a schematic diagram of reference signal distribution in LTE.For simplifying, in Fig. 1, time orientation only depicts the length (time general cyclic prefix (CP)) of a subframe, and frequency domain direction only depicts 12 subcarriers, and merely illustrates the reference signal distribution situation on a transmitting antenna port.In figure, dash area represents the position at reference signal place, in actual conditions, different side-play amounts is had on frequency domain to different cell reference signals, different distributions is had to different transmitting antenna ports, but the relative position between each reference signal is basic similar to figure, and what all adopt is this discrete reference signal location mode.Simultaneously, time-frequency conversion is carried out owing to generally adopting fast Fourier transform (FFT) in LTE system, so the length of FFT is greater than the number of actual sub-carriers, these non-existent subcarriers are empty subcarrier, and empty subcarrier does not have data not have reference signal yet.

Owing to there is empty subcarrier in LTE system, not containing any reference signal on empty subcarrier, thus receiving terminal does not know any channel information of empty subcarrier.When utilizing the frequency domain impulse response of reference signal channel to recover the time domain impulse response of channel, because empty subcarrier place does not have the frequency domain impulse response of reference signal, so the inaccurate of channel time domain impulse response and energy leakage can be caused.In existing method, be utilize the channel response at RS place in two ends in system bandwidth to do on average to the process of empty subcarrier when extracting domain channel response.Although this has certain inhibitory action to energy leakage, but still can cause larger energy leakage that the time domain impulse response of channel is forbidden, cause the time delay error that records comparatively large, thus affect receiver performance.

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

Summary of the invention

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

The present invention is that to solve the problems of the technologies described above the technical scheme adopted be a kind of channel delay method of measurement, comprises the following steps: the domain channel response obtaining reference signal place channel; Domain channel response is extracted from multiple subcarriers of channel; Judge whether sub-carrier positions is reference signal position; If sub-carrier positions is reference signal position, then directly from channel estimating, extracts corresponding domain channel response and merge; If sub-carrier positions is not reference signal position, then judge that whether this subcarrier is the subcarrier in system bandwidth; If this subcarrier is the subcarrier in system bandwidth, is similar to the reference signal place domain channel response nearest apart from this subcarrier and merges; If this subcarrier is not the subcarrier in 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 extracted; Invert fast fourier transformation is done to domain channel response, to obtain time domain channel impulse response; Calculate the tap power of time domain channel impulse response; The right tap thresholding of sending and receiving antenna is calculated according to tap power; And determine the channel delay that sending and receiving antenna is right.

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

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

In one embodiment of this invention, determine that the step of the channel delay that sending and receiving antenna is right comprises: determine for each time slot the delay spread that sending and receiving antenna is right respectively; And the time delay right to each antenna is estimated to be averaged.

In one embodiment of this invention, said method performs in containing the ofdm system receiver of empty subcarrier.

In one embodiment of this invention, said method performs in long evolving system receiver.

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

Technical scheme of the present invention is when extracting channel frequency impulse response, if be empty subcarrier, then utilize the channel response at reference signal place in two ends in system bandwidth to do linear interpolation to obtain, this contributes to the error reducing 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.More effectively can reduce energy leakage amount when transforming to time domain from frequency domain like this, improve the accuracy of time domain channel impulse response, and then estimate multipath channel time delays better, improve the accuracy of channel estimating, receiver performance is got a promotion.

Accompanying drawing explanation

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 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 of the channel delay method of measurement performing one embodiment of the invention.

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

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

Embodiment

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

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 reception antenna port, and p is transmitting antenna port, for the frequency domain received data of 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 Fig. 2, this flow process is described below:

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

Such as, LS (least square) algorithm can be used to estimate according to reference signal, obtain domain channel response

Step 202, extracts domain channel response from the multiple subcarrier of channel.At this, from the length N of receiver FFT, at interval of several (such as Δ N) individual sub-carrier extract domain channel response

In step 203, judge whether the sub-carrier positions extracted is reference signal RS position.If the sub-carrier positions extracted is the position at reference signal place, then as step 205, directly from channel estimating (as r ∈ 0,1}, p ∈ 0,1}) in extract corresponding domain channel response and merge.

If the subcarrier extracted is not in reference signal position, then judge that whether this subcarrier is the subcarrier in system bandwidth in step 204 further, if this subcarrier is the subcarrier in system bandwidth, then enters step 206 and be similar to the reference signal place domain channel response nearest apart from this subcarrier and merge.

If the subcarrier extracted is empty subcarrier (subcarrier namely in non-system 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.

Thus, in the channel frequency impulse response that step 208 is extracted.Its example is:

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

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

k _i＝round(i·ΔN/6)

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

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

The each meaning of parameters mark related in above-mentioned expression formula is as follows:

the OFDM symbol number of transmitting antenna port 0 or 1 in a subframe;

the OFDM symbol number that latency measurement uses;

the OFDM symbol numbering that latency measurement uses;

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

α _τ: linear interpolation coefficient;

system bandwidth RB number;

R, p: refer to reception antenna and transmitting antenna port respectively.

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

Such as right do IDFT conversion, obtain 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.

Such as time domain channel impulse response h _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, calculate the right tap thresholding of sending and receiving antenna according to tap power.At this, the tap thresholding of sending and receiving antenna to (r, p) is

The channel delay that sending and receiving antenna is right will be determined in step 212 and step 213.

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

Such as antenna is to the delay spread of (r, 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 represent and be greater than tap thresholding maximum diameter, represent that being greater than tap thresholding is greater than tap thresholding most path.

The delay spread of antenna to (r, p) is estimated as the mean value of this antenna to upper 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, estimate to be averaged to the time delay of (r, p) to each antenna.

Specifically, average to the delay spread value determined to each sending and receiving antenna, final delay spread estimated value is:

Fig. 3 illustrates the device schematic diagram of the channel delay method of measurement performing one embodiment of the invention.In figure 3, baseband processing chip 300 is in 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, such as, use LS to estimate to obtain domain channel response then timing time delay estimation module 320 is supplied to.Timing time delay estimation module 320, after acquisition domain channel response, can perform the step 201-213 in flow process shown in Fig. 2, finally to obtain channel delay.At this, pilot tone place channel estimation module 310, timing time delay estimation module 320 can be embodied as hardware, software or its combination.Such as, pilot tone place channel estimation module 310, regularly time delay estimation module 320 are typically embodied as the module of the program code that have cured to perform above-mentioned steps.

Owing to not containing pilot tone in empty subcarrier, the domain channel response at empty subcarrier place directly can not be obtained.If directly think that empty subcarrier place frequency domain channel is zero, then comparatively large with the error of empty subcarrier actual frequency domain channel response, empty subcarrier and non-empty subcarrier adjacent have discontinuous saltus step simultaneously, will bring larger energy leakage like this.The above embodiment of the present invention have employed following process when extracting channel frequency impulse response: if empty subcarrier, then utilize the channel response at RS place in two ends in system bandwidth to do linear interpolation to obtain, this contributes to the error reducing 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.More effectively can reduce energy leakage amount when transforming to time domain from frequency domain like this, improve the accuracy of time domain channel impulse response, and then estimate multipath channel time delays better, improve the accuracy of channel estimating, receiver performance is got a promotion.

Embodiments of the invention and existing methodical performance comparison is provided below with accompanying drawing.In Fig. 4-Fig. 6, V0503old is existing method, and V0503LineInsert is the method that embodiments of the invention adopt, and IdealEPA is the true time delay value of channel.As seen from the figure the present invention than the delay measurements of existing scheme closer to the true time delay value of channel.

Fig. 7 is the contrast of the receiver performance adopting embodiments of the invention and existing scheme, and wherein PSLI is the performance adopting inventive receiver, and Orignal is the performance of existing scheme receiver.After adopting embodiments of the invention as seen from Figure 7, because delay measurements is more accurate than existing scheme, thus the performance of the receiver of the embodiment of the present invention is also good than the performance of existing scheme receiver.

Although the present invention discloses as above with preferred embodiment; so itself and be not used to limit the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; when doing a little amendment and perfect, therefore protection scope of the present invention is when being as the criterion of defining with claims.

Claims (11)

1. a channel delay method of measurement, comprises the following steps:

Obtain the domain channel response of reference signal place channel;

Domain channel response is extracted from multiple subcarriers of channel;

Judge whether sub-carrier positions is reference signal position;

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

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

If this subcarrier is the subcarrier in system bandwidth, is similar to the reference signal place domain channel response nearest apart from this subcarrier and merges;

If this subcarrier is not the subcarrier in 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 extracted;

Invert fast fourier transformation is done to domain channel response, to obtain time domain channel impulse response;

Calculate the tap power of time domain channel impulse response;

The right tap thresholding of sending and receiving antenna is calculated according to tap power; And

Determine the channel delay that 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 extracting domain channel response from the multiple subcarrier of channel comprises, and 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 sending and receiving antenna is right comprises:

The delay spread that sending and receiving antenna is right is determined respectively for each time slot; And

The time delay right to each antenna is estimated to be averaged.

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

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

7. a channel delay measurement mechanism, comprising:

For obtaining the device of the domain channel response of reference signal place channel;

For extracting the device of domain channel response from multiple subcarriers of channel;

For judging that whether sub-carrier positions is the device of reference signal position;

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

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

If for the subcarrier that this subcarrier is in system bandwidth, be similar to the reference signal place domain channel response nearest apart from this subcarrier and carry out the device that merges;

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

For obtaining the device of the domain channel response of extraction;

For doing invert fast fourier transformation to domain channel response, to obtain the device of time domain channel impulse response;

For calculating the device of the tap power of time domain channel impulse response;

For calculating the device of the right tap thresholding of sending and receiving antenna according to tap power; And

For determining the device of the channel delay that sending and receiving antenna is right.

8. device as claimed in claim 7, is characterized in that, described is extract frequency domain response every several subcarriers for extracting the device of domain channel response from the multiple subcarrier of channel.

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

For determining the device of the delay spread that sending and receiving antenna is right respectively for each time slot; And

The device be averaged is estimated for the time delay right to each antenna.

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

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