CN101635695B - Method and device for determining maximum multipath time delay - Google Patents
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Abstract
The invention discloses a method and a device for determining maximum multipath time delay, which belong to the technical field of communication and are used for solving the problem that in the prior art, the channel estimation has overlarge errors. The method for determining the maximum multipath time delay comprises the following steps: determining a time region channel estimated value of a channel; comparing the time region channel estimated value of the channel and the preset power threshold of a channel effective path, and determining the effective path with the maximum time delay in the channel according to the comparison result; and determining the maximum multipath time delay of the channel by using the time delay corresponding to the effective path. The method and the device are used for determining the maximum multipath time delay of the channel so that the accuracy of the channel estimation can be improved by using the maximum multipath time delay determined by the method and the device so as to improve the system performance.
Description
Technical field
The present invention relates to communication technical field, relate in particular to a kind of definite maximum multipath time delay τ
MaxMethod, system and device.
Background technology
In OFDM (OFDM, Orthogonal Frequency Division Multiplex) system, use least mean-square error (MMSE, Minimum Mean Square Error) algorithm generally can obtain good channel estimating effect.
The MMSE algorithm is the channel estimation method that utilizes pilot tone point, is the channel estimating of carrying out obtaining after the interpolation other subcarriers according to the frequency domain auto-correlation information of channel.Therefore, when using the MMES algorithm, need know the frequency domain autocorrelation matrix of channel, and the maximum multipath time delay N of the frequency domain autocorrelation matrix of channel and channel
τ maxRelevant.
In the ofdm system in order to eliminate intersymbol interference (ISI fully; Intersymbol Interference), introduced Cyclic Prefix (CP, Cyclic Prefix); The time delay expansion of ordinary circumstance lower channel can not surpass the length of CP; Therefore, at present during the frequency domain auto-correlation function of calculating channel, general not to the maximum multipath time delay N of channel
τ maxEstimate, and directly think maximum multipath time delay N
τ maxEqual the length of CP.
But, can find through emulation, in the prior art directly with the CP length of system maximum multipath time delay N as channel
τ maxWay can cause channel estimation results not accurate enough, exist than mistake sometimes, thereby influence the demodulation performance of system, cause systematic function to reduce greatly.
In sum, prior art is not because to maximum multipath time delay N
τ maxEstimate, but directly replace, cause the channel estimation errors of system bigger, influence the demodulation performance of system, make systematic function reduce greatly with CP length.
Summary of the invention
The embodiment of the invention provides a kind of method and device of definite maximum multipath time delay, in order to obtaining maximum multipath time delay more accurately, thereby reduces the channel estimation errors of system, improves systematic function.
The method of a kind of definite maximum multipath time delay that the embodiment of the invention provides comprises:
Estimate through the OFDM symbol that comprises pilot signal in the channel being carried out frequency domain channel, obtain the frequency domain channel estimated value, and, confirm the time domain channel estimated value of channel through said frequency domain channel estimated value is carried out inverse discrete Fourier transformer inverse-discrete;
The power threshold of the time domain channel estimated value of said channel with the channel effective diameter that is provided with in advance compared, and confirm the maximum effective diameter of time delay in the said channel according to comparative result;
Sample frequency according to system is carried out conversion to the maximum pairing time delay of effective diameter of said time delay, confirms the maximum multipath time delay of channel;
Wherein, said frequency domain channel estimated value is carried out inverse discrete Fourier transformer inverse-discrete, confirm that the time domain channel estimated value specifically comprises: according to the maximum multipath time delay that the length of the Cyclic Prefix of system or last one-period are confirmed, the target window of setting the time domain channel estimating window is long; When the target window length of said time domain channel estimating window be less than or equal to time domain channel estimating window that the pilot interval that utilizes said frequency domain channel to estimate calculates when front window is grown; Utilize said target window long and said long, calculate the multiple that said frequency domain channel estimated value is extracted when front window; According to said multiple said frequency domain channel estimated value is extracted, and the frequency domain channel estimated value that extracts is carried out inverse discrete Fourier transformer inverse-discrete, confirm the time domain channel estimated value.
The device of a kind of definite maximum multipath time delay that the embodiment of the invention provides comprises:
Time-domain channel estimating unit; Being used for carrying out frequency domain channel through the OFDM symbol that channel is comprised pilot signal estimates; Obtain the frequency domain channel estimated value, and, confirm the time domain channel estimated value of channel through said frequency domain channel estimated value is carried out inverse discrete Fourier transformer inverse-discrete;
Comparing unit is used for the power threshold of the time domain channel estimated value of channel with the channel effective diameter that is provided with in advance compared, and confirms the maximum effective diameter of time delay in the said channel according to comparative result;
The maximum multipath time delay unit carries out conversion according to the sample frequency of system to the maximum pairing time delay of effective diameter of said time delay, confirms the maximum multipath time delay of channel;
Wherein, said time-domain channel estimating unit specifically is used for, and according to the maximum multipath time delay that the length of the Cyclic Prefix of system or last one-period are confirmed, the target window of setting the time domain channel estimating window is long; When the target window length of said time domain channel estimating window be less than or equal to time domain channel estimating window that the pilot interval that utilizes said frequency domain channel to estimate calculates when front window is grown; Utilize said target window long and said long, calculate the multiple that said frequency domain channel estimated value is extracted when front window; According to said multiple said frequency domain channel estimated value is extracted, and the frequency domain channel estimated value that extracts is carried out inverse discrete Fourier transformer inverse-discrete, confirm the time domain channel estimated value.
The embodiment of the invention is confirmed the time domain channel estimated value of channel, the power threshold of the time domain channel estimated value of said channel with the channel effective diameter that is provided with is in advance compared, and confirm the maximum effective diameter of time delay in the said channel according to comparative result; Utilize the corresponding time delay of said effective diameter to confirm the maximum multipath time delay of channel; Obtain maximum multipath time delay more accurately; Thereby when utilizing this maximum multipath time delay to carry out channel estimating, can improve the channel estimating effect of system, reduce error; Thereby improve the demodulation performance of system, make systematic function improve greatly.
Description of drawings
The group method schematic flow sheet of a kind of definite maximum multipath time delay that Fig. 1 provides for the embodiment of the invention;
The concrete grammar schematic flow sheet of a kind of definite maximum multipath time delay that Fig. 2 provides for the embodiment of the invention;
The apparatus structure sketch map of a kind of definite maximum multipath time delay that Fig. 3 provides for the embodiment of the invention.
Embodiment
The embodiment of the invention provides a kind of method and device of definite maximum multipath time delay, in order to obtaining maximum multipath time delay more accurately, thereby improves the channel estimating effect and the demodulation performance of system, makes systematic function improve greatly.
The said tap of the embodiment of the invention is meant the channel estimation value on each sampled point in the time domain channel estimating window, and said tap comprises effective diameter and noise path.
Below in conjunction with accompanying drawing the embodiment of the invention is described.
Referring to Fig. 1, the method for a kind of definite maximum multipath time delay that the embodiment of the invention provides totally comprises step:
S101, confirm the time domain channel estimated value of channel.
S102, the power threshold of the time domain channel estimated value of channel with the channel effective diameter that is provided with in advance compared, and confirm the maximum effective diameter of time delay in the channel according to comparative result.
S103, utilize the maximum pairing time delay of effective diameter of time delay in the channel, confirm the maximum multipath time delay of channel.
Preferably, the method for definite maximum multipath time delay that the embodiment of the invention provides is to carry out in the cycle, can be that every frame carries out once, also can be that every separated some frames carry out once.Promptly before step S101, further comprise the step of monitoring predetermined period, when the cycle arrives, execution in step S101.And; Preferably; After step S103 has confirmed the maximum multipath time delay of channel in the current period; Further calculated the maximum multipath time delay of channel in the current period and the mean value of the maximum multipath time delay of this channel in last one-period, and upgrade the maximum multipath time delay of the interior channel of current period with this mean value.
Step S101 confirms that the method for the time domain channel estimated value of channel can have multiple; For example, generally speaking, in ofdm system in order to reduce overhead; Pilot signal is inserted at frequency domain; So can try to achieve the frequency domain channel estimated value earlier, again it is transformed on the time domain, thereby obtains the time domain channel estimated value.
Prior art has mainly been considered the influence of pilot tone point density degree to channel estimating performance, and has not been considered the application of pilot tone point in measuring maximum multipath time delay when the design pilot tone.Therefore; Preferably, utilize the maximum multipath time delay that CP length or the one-period of lasting of system confirm in the embodiment of the invention, the target window of setting time domain channel estimating window is long; And when this target window length be less than or equal to time domain channel estimating window that the pilot interval that utilizes frequency domain channel to estimate calculates when front window is grown; Can again its method that is transformed into time domain be obtained the time domain channel estimated value through at interval extracting the frequency domain channel estimated value, so just avoid pilot tone point density degree and the unmatched problem of channel maximum multipath time delay, time delay expand than hour; Avoid because pilot interval is too little; Chosen too much and counted, thereby caused having increased insignificant operand, described below in conjunction with specific embodiment.
As shown in Figure 2, the concrete grammar of a kind of definite maximum multipath time delay that the embodiment of the invention provides comprises step:
S201, utilize following formula that the frequency domain channel of carrying out of the OFDM symbol that comprises pilot signal in the channel is estimated:
Wherein,
Represent n the channel estimating on the OFDM symbol the i ' number of sub-carrier, R
N, i 'Represent n the reception signal on the OFDM symbol the i ' number of sub-carrier, S
N, i 'Represent n the transmission signal on the OFDM symbol the i ' number of sub-carrier, the position of pilot sub-carrier on the i ' expression OFDM symbol, and,
Wherein, N
pThe pilot interval that the expression frequency domain channel is estimated is used for frequency domain channel and estimates; N
OccupyThe number of effective subcarrier in the bandwidth of expression pilot distribution.
S202, utilize the CP length N of system
Cp, or definite maximum multipath time delay N ' of last one-period
τ max, the target window of setting the time domain channel estimating window is long, and the pilot interval N that utilizes frequency domain channel to estimate
pCalculate the long when front window of time domain channel estimating window, concrete grammar comprises following two steps:
Step a, make N
τ=a*N '
τ maxOr N
τ=N
Cp
Wherein, use N
τThe target window of expression time domain channel estimating window is long; The frequency domain channel estimated value of a plurality of pilot tone points that are used for step S201 is obtained is carried out interpolation; A representes to lose the long parameter that suitably strengthens of the target window with the time domain channel estimating window that is adopted for fear of multipath, and a＞1.
Also do not obtaining N '
τ maxBefore, when promptly initial, can adopt N
τ=N
CpDispose.
In the embodiment of the invention, the operation of confirming maximum multipath time delay is to carry out in the cycle, therefore, before the step S201, also comprises the step of monitoring predetermined period, execution in step S201 when the cycle arrives.
The target window length of above-mentioned setting time domain channel estimating window is in order to reduce amount of calculation; The embodiment of the invention adopt CP length or the one-period of lasting definite maximum multipath time delay to set the target window of time domain channel estimating window long; Can guarantee time domain channel estimating window long enough; Make effective multipath can not fall outside window, counting that the participation frequency domain channel is estimated is abundant, but can too much not cause the increase of amount of calculation.
Therefore, the value of above-mentioned parameter a is greater than 1, makes that the long change of target window of current time domain channel estimating window is big, means and can seek effective multipath in the larger context, thereby avoid definite maximum multipath time delay N ' of one-period
τ maxEstimate inaccurate and multipath that bring is lost.
If the window of time domain channel estimating window is long too small, then can not estimate the maximum multipath time delay outside the time domain channel estimating window, therefore, preferably,, N can be set periodically for fear of error
τ=N
CpCalibrate.
Step b, utilize N
pValue calculate the time domain channel estimating window when front window long, promptly
Wherein, N
IFFTThe number of the sampled point that expression participation system inverse fast Fourier transform (IFFT, Inverse Fast Fourier Transform) is handled is promptly long through the window that the frequency domain channel estimated value is carried out the time domain channel estimating window that conversion obtains.N
IFFTBe typical ofdm system parameter, in ofdm system, utilize subcarrier in frequency domain to carry data, send after transforming to time domain through IFFT at last.
S203, when the target window length of time domain channel estimation window be less than or equal to time domain channel estimating window that the pilot interval that utilizes frequency domain channel to estimate obtains when front window is grown; The multiple k that the frequency domain channel estimated value that calculating obtains step S201 extracts, and according to the value of k the frequency domain channel estimated value is extracted.
Concrete, judge whether to satisfy following formula:
If satisfy, then according to the value of computes k:
When the target window length of time domain channel estimation window is excessive, multipath will concentrate on before the time domain channel estimating window, and after the time domain channel estimating window is noise path entirely; And long excessive meaning of the target window of time domain channel estimating window participated in inverse discrete Fourier transformer inverse-discrete (IDFT; Inverse Discrete Fourier Transform) frequency domain channel estimated value can be many, and too much frequency domain channel estimated value there is no need, so in order to reduce operand; The frequency domain channel estimated value being carried out k here doubly extracts; For example, calculate 100 frequency domain channel estimated values among the step S201, and the value of the k that calculates is 5; Then from 100 frequency domain channel estimated values, extract the 5th, the 10th, the 15th, the 20th respectively ... the frequency domain channel estimated value extracts 20 frequency domain channel estimated values at last altogether.
S204, the frequency domain channel estimated value that k is doubly extracted are carried out the IDFT conversion, obtain the time domain channel estimated value.
S205, according to the sequential search of last tap in the long scope of the target window of the time domain channel estimating window of confirming from step a to first tap, when first time domain channel estimated value that finds greater than the tap of the power threshold of channel effective diameter as the maximum effective diameter of time delay.
Need to prove; The operation that embodiment of the invention step S205 searches the maximum effective diameter of time delay is a kind of preferred implementation, and purpose is to save and searches the time, because in the time domain channel estimating window; Each effective diameter is according to from small to large tactic of time delay; Therefore, can pick up speed according to from back to front sequential search tap, because what search is the maximum tap of time delay.Certainly, also can search from front to back, with last time domain channel estimated value that finds greater than the tap of the power threshold of channel effective diameter as the maximum effective diameter of time delay, still, can waste the time of searching like this.
In the embodiment of the invention, with the noise power η of channel
nMultiply by factor beta, with β * η
nPower threshold as the channel effective diameter.
Wherein, the method that noise power is obtained is many, and the value of β also can have multiple, preferably, can be 4.5dB.
In addition, can also there be other modes that the power threshold of channel effective diameter is set, for example, in the long scope of the window of time domain channel estimating window, find maximum tap power, it multiply by a coefficient, as the power threshold of channel effective diameter.
S206, the maximum pairing time delay N of effective diameter of time delay that step S205 is confirmed
O_tmaxCarry out conversion by the systematic sampling frequency, obtain the corresponding maximum multipath time delay of a certain antenna of channel in the current period.
Particularly, according to following formula to N
O_tmaxCarry out conversion by the systematic sampling frequency:
Because pilot tone point does not in most cases take whole bandwidth, can cause the interval of the time-domain signal sampled point after IDFT handles to change in this case.Therefore, need carry out conversion, thereby guarantee the N that step S206 obtains by the systematic sampling frequency
τ maxWith the systematic sampling frequency is unit.
Preferably, in order to make measurement result more accurate, can further carry out following two steps:
S207, all try to achieve N to step S206 according to step S201 for the OFDM symbol that comprises pilot tone on each antenna
τ max, and to N corresponding on these antenna
τ maxGet average, obtain the maximum multipath time delay more accurately of channel in the current period.
S208, the maximum multipath time delay that estimates is carried out between subframe level and smooth.
Suppose that maximum multipath time delay that a last subframe measures for the maximum multipath time delay of the channel of
then current subframe after level and smooth is:
Wherein, α is a smoothing factor, and smoothing factor should be the amount that changes along with the variation of the translational speed of user terminal, but in real system, the translational speed of user terminal is difficult to obtain, and therefore can adopt fixed value, and is preferable, can be 0.5.
Introduce the device that the embodiment of the invention provides below.
Referring to Fig. 3, the device of a kind of definite maximum multipath time delay that the embodiment of the invention provides comprises:
Time-domain channel estimating unit 301 is used for confirming the time domain channel estimated value of channel.
Comparing unit 302 is used for the power threshold of the time domain channel estimated value of channel with the channel effective diameter that is provided with in advance compared, and confirms the maximum effective diameter of time delay in the said channel according to comparative result.
Maximum multipath time delay unit 303 is used to utilize the corresponding time delay of said effective diameter to confirm the maximum multipath time delay of channel.
Preferably, said comparing unit 302 comprises:
Preferably, the tap of time domain channel estimated value greater than the power threshold of the channel effective diameter that is provided with in advance in the long scope of the window of the time domain channel estimating window of channel, according to the order from last tap to first tap, searched in the said unit 3021 of searching; Said definite unit 3022, with said search unit 3021 first time domain channel estimated values that find greater than the tap of the power threshold of the channel effective diameter that is provided with in advance as the maximum effective diameter of time delay.
Preferably, the device of a kind of definite maximum multipath time delay of providing of the embodiment of the invention also comprises: cycle monitoring unit 304 and updating block 305.Cycle monitoring unit 304 is used to monitor predetermined period, when the cycle arrives, triggers time-domain channel estimating unit 301.At this moment, time-domain channel estimating unit 301 when receiving the triggering of said cycle monitoring unit 304, is confirmed the time domain channel estimated value of channel.Said maximum multipath time delay unit 303 triggers updating block 305 when having confirmed the maximum multipath time delay of channel in this cycle.Updating block 305; Be used for when receiving the triggering of said maximum multipath time delay unit 303; To the maximum multipath time delay weighted sum of the maximum multipath time delay of the said channel confirmed in this cycle and the said channel confirmed in last one-period, and the value of the maximum multipath time delay of said channel in this cycle is updated to the resulting value of said weighted sum.
In sum; In the embodiment of the invention, estimate, transform to time domain to the channel estimating of pilot tone point then through pilot signal being carried out frequency domain channel at frequency domain; Obtain the channel maximum multipath time delay after time domain channel is estimated; Utilize this maximum multipath time delay to carry out channel estimating, make estimated result more accurate, thereby improve systematic function.And; Further; The embodiment of the invention is reset the pilot interval of current participation time domain channel estimation according to the CP length of system or the channel maximum multipath time delay that measures before; Compare the too big problem of operand when having avoided system pilot overstocked at interval at interval with directly adopting default system pilot in the prior art.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, belong within the scope of claim of the present invention and equivalent technologies thereof if of the present invention these are revised with modification, then the present invention also is intended to comprise these changes and modification interior.
Claims (12)
1. the method for a definite maximum multipath time delay is characterized in that, this method comprises:
Estimate through the OFDM symbol that comprises pilot signal in the channel being carried out frequency domain channel, obtain the frequency domain channel estimated value, and, confirm the time domain channel estimated value of channel through said frequency domain channel estimated value is carried out inverse discrete Fourier transformer inverse-discrete;
The power threshold of the time domain channel estimated value of said channel with the channel effective diameter that is provided with in advance compared, and confirm the maximum effective diameter of time delay in the said channel according to comparative result;
Sample frequency according to system is carried out conversion to the maximum pairing time delay of effective diameter of said time delay, confirms the maximum multipath time delay of channel;
Wherein, said frequency domain channel estimated value is carried out inverse discrete Fourier transformer inverse-discrete, confirm that the time domain channel estimated value specifically comprises: according to the maximum multipath time delay that the length of the Cyclic Prefix of system or last one-period are confirmed, the target window of setting the time domain channel estimating window is long; When the target window length of said time domain channel estimating window be less than or equal to time domain channel estimating window that the pilot interval that utilizes said frequency domain channel to estimate calculates when front window is grown; Utilize said target window long and said long, calculate the multiple that said frequency domain channel estimated value is extracted when front window; According to said multiple said frequency domain channel estimated value is extracted, and the frequency domain channel estimated value that extracts is carried out inverse discrete Fourier transformer inverse-discrete, confirm the time domain channel estimated value.
2. method according to claim 1 is characterized in that, the said front window length of working as is:
Wherein, N
IFFTThe number of the sampled point that expression participation system inverse fast Fourier transform is handled, N
pRepresent the pilot interval that said frequency domain channel is estimated.
3. method according to claim 2 is characterized in that, utilizes computes to obtain the multiple that said frequency domain channel estimated value is extracted:
Wherein, k representes said multiple, N
IFFTThe number of the sampled point that expression participation system inverse fast Fourier transform is handled, N
pRepresent the pilot interval that said frequency domain channel is estimated, N
τRepresent that said target window is long.
4. method according to claim 1 is characterized in that, the target window length that the cycle is provided with said time domain channel estimating window is the length of said Cyclic Prefix.
5. method according to claim 1 and 2 is characterized in that, the time domain channel estimated value of the effective diameter correspondence that said time delay is maximum is greater than the power threshold of the channel effective diameter that is provided with in advance.
6. method according to claim 5 is characterized in that, confirms that the step of the effective diameter of time delay maximum in the said channel comprises:
In the long scope of the window of the time domain channel estimating window of channel,, search of the tap of time domain channel estimated value greater than the power threshold of the channel effective diameter that is provided with in advance according to order from last tap to first tap;
With first time domain channel estimated value that finds greater than the tap of the power threshold of the channel effective diameter that is provided with in advance as the maximum effective diameter of time delay.
7. method according to claim 1 is characterized in that this method also comprises the monitoring predetermined period, and according to said predetermined period, periodic triggers is carried out the step of the time domain channel estimated value of said definite channel.
8. method according to claim 7 is characterized in that, in each cycle, when having confirmed the maximum multipath time delay of said channel in this cycle, this method also comprises:
Maximum multipath time delay to the maximum multipath time delay of the said channel confirmed in this cycle and the said channel confirmed in last one-period carries out weighting summation;
The value of the maximum multipath time delay of said channel in this cycle is updated to the value that obtains behind the said weighting summation.
9. the device of a definite maximum multipath time delay is characterized in that, said device comprises:
Time-domain channel estimating unit; Being used for carrying out frequency domain channel through the OFDM symbol that channel is comprised pilot signal estimates; Obtain the frequency domain channel estimated value, and, confirm the time domain channel estimated value of channel through said frequency domain channel estimated value is carried out inverse discrete Fourier transformer inverse-discrete;
Comparing unit is used for the power threshold of the time domain channel estimated value of channel with the channel effective diameter that is provided with in advance compared, and confirms the maximum effective diameter of time delay in the said channel according to comparative result;
The maximum multipath time delay unit is used for according to the sample frequency of system the maximum pairing time delay of effective diameter of said time delay being carried out conversion, confirms the maximum multipath time delay of channel;
Wherein, said time-domain channel estimating unit specifically is used for, and according to the maximum multipath time delay that the length of the Cyclic Prefix of system or last one-period are confirmed, the target window of setting the time domain channel estimating window is long; When the target window length of said time domain channel estimating window be less than or equal to time domain channel estimating window that the pilot interval that utilizes said frequency domain channel to estimate calculates when front window is grown; Utilize said target window long and said long, calculate the multiple that said frequency domain channel estimated value is extracted when front window; According to said multiple said frequency domain channel estimated value is extracted, and the frequency domain channel estimated value that extracts is carried out inverse discrete Fourier transformer inverse-discrete, confirm the time domain channel estimated value.
10. device according to claim 9 is characterized in that, said comparing unit comprises:
Search the unit, be used in the long scope of the window of the time domain channel estimating window of channel, searching of the tap of time domain channel estimated value greater than the power threshold of the channel effective diameter that is provided with in advance;
Confirm the unit, be used for searching the maximum tap of time delay that the unit finds as the maximum effective diameter of time delay said.
11. device according to claim 10; It is characterized in that; The said unit of searching; In the long scope of the window of the time domain channel estimating window of channel,, search of the tap of time domain channel estimated value greater than the power threshold of the channel effective diameter that is provided with in advance according to order from last tap to first tap;
Said definite unit, with said search first time domain channel estimated value that finds of unit greater than the tap of the power threshold of the channel effective diameter that is provided with in advance as the maximum effective diameter of time delay.
12., it is characterized in that said device also comprises according to claim 9,10 or 11 described devices: cycle monitoring unit and updating block,
Said cycle monitoring unit is used to monitor predetermined period, and according to said predetermined period, the said time-domain channel estimating unit of periodic triggers;
Said time-domain channel estimating unit when receiving the triggering of said cycle monitoring unit, is confirmed the time domain channel estimated value of channel;
Said maximum multipath time delay unit in each cycle, triggers said updating block when having confirmed the maximum multipath time delay of said channel in this cycle;
Said updating block; Be used for when receiving the triggering of said maximum multipath time delay unit; Maximum multipath time delay to the maximum multipath time delay of the said channel confirmed in this cycle and the said channel confirmed in last one-period carries out weighting summation, and the value of the maximum multipath time delay of said channel in this cycle is updated to the value that obtains behind the said weighting summation.
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| CN101854190B (en) * | 2010-05-24 | 2013-02-13 | 西华大学 | Multipath subduction method based on frequency domain transfer function estimation |
| CN102158949A (en) * | 2011-03-22 | 2011-08-17 | 京信通信***（中国）有限公司 | Synchronous extraction method of GSM (global system for mobile communications)/EDGE (enhanced data rates for GSM evolution) communication system and device thereof |
| CN103188189B (en) * | 2011-12-27 | 2016-03-09 | 联芯科技有限公司 | Channel delay method of measurement and device |
| CN108512713B (en) * | 2017-02-28 | 2023-02-28 | 中兴通讯股份有限公司 | Method and device for calculating time delay |
| CN110099022B (en) * | 2018-01-31 | 2020-07-28 | 大唐移动通信设备有限公司 | Multipath time delay estimation method and device |
| CN112335290A (en) | 2018-06-18 | 2021-02-05 | Abb瑞士股份有限公司 | Path selection in a wireless communication system |
| CN111614592B (en) * | 2019-02-25 | 2023-03-21 | 北京小米松果电子有限公司 | Method and device for determining multipath selection threshold, storage medium and electronic equipment |
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| CN101047460A (en) * | 2006-03-30 | 2007-10-03 | 华为技术有限公司 | Counting method for transmission delay of physical random access channel |
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