CN111786917A - Channel estimation method, receiver and storage medium - Google Patents
Channel estimation method, receiver and storage medium Download PDFInfo
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- CN111786917A CN111786917A CN202010768857.3A CN202010768857A CN111786917A CN 111786917 A CN111786917 A CN 111786917A CN 202010768857 A CN202010768857 A CN 202010768857A CN 111786917 A CN111786917 A CN 111786917A
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
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- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/309—Measuring or estimating channel quality parameters
Abstract
The embodiment of the application provides a channel estimation method, a receiver and a storage medium. The method comprises the following steps: receiving a pilot signal; acquiring a power time delay spectrum PDP of a pilot signal; detecting whether a target path exists in the PDP, wherein the target path is a main path comprising a direct path; and when the target path exists in the PDP, determining Doppler spread parameters according to the maximum value and the minimum value in the frequency offset estimation value of each subframe in the frequency offset change period. According to the technical scheme provided by the embodiment of the application, whether the current channel environment obeys Rice distribution or not is judged, and under the condition that the current channel obeys Rice distribution, the Doppler spread parameter is estimated through the maximum value and the minimum value in the frequency deviation estimated value of each subframe in the frequency deviation change period, so that the accuracy of channel estimation is improved, the error rate is reduced, and the throughput of a system is improved.
Description
Technical Field
The present disclosure relates to the field of wireless communications technologies, and in particular, to a channel estimation method, a receiver, and a storage medium.
Background
After being transmitted from a transmitting end, data reaches a receiving end through the propagation of a wireless channel, and various interference factors in the wireless channel can affect the transmitted data, so that a channel estimation scheme is generally adopted to perform equalization processing on the received data, and the influence of the wireless channel is overcome to recover the data.
In the related art, channel estimation is performed in the following manner: assuming that the channel is subject to a rayleigh fading model, then channel estimation is performed with respect to the rayleigh fading model, such as estimating a doppler spread parameter based on a U-shaped spectrum and a bezier function of order 0.
Disclosure of Invention
The embodiment of the application provides a channel estimation method, a receiver and a storage medium. The technical scheme is as follows:
in one aspect, an embodiment of the present application provides a channel estimation method, where the method includes:
receiving a pilot signal;
acquiring a Power Delay Profile (PDP) of the pilot signal;
detecting whether a target path exists in the PDP, wherein the target path is a main path comprising a direct path;
and when the target diameter exists in the PDP, determining Doppler spread parameters according to the maximum value and the minimum value in the frequency offset estimation values of all subframes in the frequency offset change period.
In another aspect, the present application provides a receiver, comprising:
a receiving unit for receiving a pilot signal;
a processing unit to:
acquiring a PDP of the pilot signal;
detecting whether a target path exists in the PDP, wherein the target path is a main path comprising a direct path;
and when the target diameter exists in the PDP, determining Doppler spread parameters according to the maximum value and the minimum value in the frequency offset estimation values of all subframes in the frequency offset change period.
In yet another aspect, embodiments of the present application provide a receiver, which includes a processor, a memory, and a computer program stored in the memory, where the computer program is loaded into and executed by the processor to implement the channel estimation method according to the aspect.
In yet another aspect, embodiments of the present application provide a computer-readable storage medium, where a computer program is stored, and the computer program is loaded and executed by a processor to implement the channel estimation method according to the aspect.
In yet another aspect, an embodiment of the present application provides a computer program product, where the computer program product includes computer instructions stored in a computer-readable storage medium, and a processor of a computer device reads the computer instructions from the computer-readable storage medium, and executes the computer instructions, so that the computer device performs the channel estimation method provided in the foregoing aspect or various alternative implementations of the aspect.
The technical scheme provided by the embodiment of the application can bring the beneficial effects of at least comprising:
after receiving a pilot signal, determining whether the current channel environment obeys Rayleigh distribution or not based on whether a main path containing a direct path exists in a PDP of the pilot signal or not, if the PDP contains the main path containing the direct path, determining that the current channel environment does not obey Rayleigh distribution but obey Rayleigh distribution, and estimating Doppler spread parameters through the maximum value and the minimum value in frequency offset estimation values of all subframes in a frequency offset change period, so that the accuracy of channel estimation is improved, the error rate is reduced, and the throughput of a system is improved.
Drawings
Fig. 1 is a schematic diagram of a wireless communication system provided by an embodiment of the present application;
fig. 2 is a flow chart of a channel estimation method provided by an embodiment of the present application;
fig. 3 is a flow chart of a channel estimation method according to another embodiment of the present application;
FIG. 4 is a schematic diagram of a PDP according to an embodiment of the present application;
FIG. 5 is a schematic illustration of power spectral density provided by an embodiment of the present application;
fig. 6 is a flow chart of a channel estimation method according to another embodiment of the present application;
FIG. 7 is a block diagram of a receiver provided by one embodiment of the present application;
fig. 8 is a block diagram of a receiver according to another embodiment of the present application.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
First, the related terms related to the embodiments of the present application will be explained.
Rayleigh fading channel: a statistical model of the propagation environment of a radio signal in which the probability density function of the envelope of the signal after passing through a radio channel obeys Rayleigh distributions. The rayleigh fading model is suitable for the case that the transmitter and the receiver do not have direct signals, such as short wave channels reflected by ionosphere and troposphere, urban environment with dense buildings, and the like.
The probability density function of the rayleigh distribution is represented by the following formula:
σ2is the power of the multipath signal component.
Rice fading channel: a statistical model of the propagation environment of a radio signal, in which the probability density function of the envelope of the signal after it has passed through the radio channel follows a Rice distribution. The rayleigh fading model is suitable for the situation that a direct signal exists between a transmitter and a receiver, such as a high-speed rail channel environment and the like.
The probability density function of the rice distribution is expressed by the following formula:
r is the envelope of the sinusoidal signal plus the narrow-band Gaussian random signal, A is the peak of the amplitude of the principal signal, σ2Is the power of the multipath signal component, J0(. cndot.) is a modified 0 th order Bessel function of the first kind.
Doppler spread: due to multipath propagation, the transmitter transmits at a frequency f0The signal received by the receiver is a plurality of sub-signals with different arrival directionsThe Doppler frequency of the sub-paths with different arrival directions is different, and the multi-path signal synthesized by each sub-path signal is a transmission signal at f0-max，f0+max]Spreading in the frequency range, i.e. doppler spreading.
Direct irradiation path: there is no path shielded by object between the transmitter and the receiver, the power is usually large, and the current channel environment obeys rice distribution in the presence of direct path.
Referring to fig. 1, a schematic diagram of a wireless communication system provided by an embodiment of the present application is shown. The wireless communication system may be a Long Term Evolution (LTE) system, a 5th Generation (5G) system, or other systems that may be present in the future. The wireless communication system includes: a transmitter 11, a receiver 12.
The transmitter 11 is used to transmit a pilot signal. The transmitter 11 includes, but is not limited to: user Equipment (UE), relay station, base station, and so on. The receiver 12 is used to receive the pilot signal transmitted by the transmitter. The receiver 12 includes, but is not limited to: UE, relay station, base station, etc.
When the channel estimation method is used for estimating an uplink channel, in the uplink channel, if the transmitter 11 transmitting the pilot signal is a UE, the receiver 12 is a base station or a relay station, and if the transmitter 11 transmitting the pilot signal is a relay station, the receiver 12 is a base station or a previous hop relay station. When the channel estimation method is used for estimating an uplink channel, in the downlink channel, if the transmitter 11 that transmits the pilot signal is a base station, the receiver 12 is a terminal or a relay station, and if the transmitter 11 that transmits the pilot signal is a relay station, the receiver 12 is a terminal or a next hop relay station.
In the embodiment of the present application, only the channel estimation method is used to estimate the uplink channel, and the transmitter 11 is a base station and the receiver 12 is a terminal.
In the related art, under the condition that the channel does not conform to the rayleigh fading model, for example, when a direct signal exists, the channel obeys the leis fading model, and at this time, when the channel estimation method provided by the related art is adopted for channel estimation, the accuracy of channel estimation is low.
Based on this, an embodiment of the present application provides a channel estimation method, where after receiving a pilot signal, it is determined whether a current channel environment is compliant with rayleigh distribution based on whether a primary path including a direct path exists in a PDP of the pilot signal, and if the PDP includes the primary path including the direct path, it is determined that the current channel environment is not compliant with rayleigh distribution but compliant with rice distribution, at this time, a channel estimation method provided by a related technology is not adopted to estimate a doppler spread parameter, but a doppler spread parameter is estimated through a maximum value and a minimum value in a frequency offset estimation value of each subframe in a frequency offset change period, so that accuracy of channel estimation is improved, thereby reducing an error rate and improving throughput of a system.
Referring to fig. 2, a flow chart of a channel estimation method provided by the embodiment of the present application is shown, and the method is applied to the receiver 12 in fig. 1. The method comprises the following steps:
The receiving end receives the pilot signal sent by the sending end. A pilot signal is a signal, usually a single frequency, also referred to as a reference signal, transmitted within the telecommunications network for measurement or monitoring purposes.
The power delay profile is used to describe the dispersion of the channel over time. Since the time that the pilot signal travels through different paths to reach the receiver is different, a phenomenon of signal time dispersion is caused, and a power delay spectrum is used to describe the phenomenon.
After receiving the pilot signal, the receiving end performs channel estimation on the received pilot signal to obtain a channel response of the pilot signal in the frequency domain, and then performs fourier transform on the channel response of the pilot signal in the frequency domain to obtain a channel response of the pilot signal in the time domain. And then, acquiring the power delay spectrum of the pilot signal in at least two time slots according to the channel response of the pilot signal in the time domain.
The target path refers to the main path including the direct path. The power of the direct path is strong, and the direct path is also called a rice path because the channel model follows rice distribution in the presence of the direct path.
Optionally, the receiver detects whether the target path is included in the PDP by the following sub-steps:
step 203a, selecting M maximum paths from the PDP according to the power of the paths included in the PDP, wherein M is a positive integer.
Optionally, the receiver sorts the paths included in the PDP in order of decreasing power, and then selects, as M maximum paths, paths with power rank M bits ahead from among the paths included in the PDP according to the sorting result. The value of M is set experimentally or empirically, and is illustratively 3.
And step 203b, acquiring signal-to-noise ratio parameters corresponding to the M maximum diameters according to the signal-to-noise ratios corresponding to the M maximum diameters respectively.
The signal-to-noise ratio is the ratio between the power of the maximum path and the noise power, expressed in decibels. Optionally, the receiver acquires the noise power and the powers of the M maximum paths from the PDP, and then calculates the signal-to-noise ratios respectively corresponding to the M maximum paths according to the acquired noise power and the powers of the M maximum paths.
Optionally, the signal-to-noise ratio parameter is a parameter associated with the signal-to-noise ratio, such as a signal-to-noise ratio variance, a parameter obtained based on the signal-to-noise ratio variance, and the like. In the embodiments of the present application, the signal-to-noise ratio parameter is merely used as an example of the signal-to-noise ratio variance, which is a parameter for measuring the degree of deviation between a random variable and its mathematical expectation (i.e., mean). Optionally, the receiver obtains signal-to-noise ratio variances corresponding to the M maximum paths according to the signal-to-noise ratios corresponding to the M maximum paths, respectively. Illustratively, the receiver calculates the variance s corresponding to the M maximum paths by the following formula2：
Wherein x isiRepresenting the signal-to-noise ratio of the ith maximum diameter in the M maximum diameters, i being a positive integer less than or equal to MAnd x is the average of the signal-to-noise ratios of the M maximum paths.
And 203c, detecting whether the target path exists in the PDP according to the signal-to-noise ratio parameters corresponding to the M maximum paths.
And when the signal-to-noise ratio parameter is the signal-to-noise ratio variance, the receiver detects whether the target path exists in the PDP according to the signal-to-noise ratio variance corresponding to the M maximum paths. Optionally, when the signal-to-noise ratio variance corresponding to the M maximum paths is smaller than a first threshold, it is determined that a target path exists in the PDP. And when the signal-to-noise ratio variance corresponding to the M maximum paths is larger than a first threshold value, determining that no target path exists in the PDP. The value of the first threshold is set according to experiments or experience, and the embodiment of the present application does not limit this.
In the embodiment of the present application, for example, the receiver selects M maximum paths from the PDP of the pilot signal in each timeslot, then calculates signal-to-noise ratios corresponding to the M maximum paths, and determines the maximum path as a target path, that is, a main path including a direct path, when there is a maximum path whose variance indicating a change in the signal-to-noise ratio is smaller than a first threshold.
Optionally, after acquiring the PDP of the pilot signal, the receiving end performs summation filtering on the PDP to obtain a filtered PDP.
Optionally, before selecting the M maximum paths, the receiver performs cyclic shift on the filtered power delay spectrum, and then selects the M maximum paths according to the power of the paths included in the PDP. By the method, the situation that paths positioned at the forefront and the last in the power delay spectrum cannot be screened is avoided.
When the target path exists in the PDP, it is determined that the current channel environment obeys rice distribution, and when it is assumed that the channel environment obeys rayleigh distribution and channel estimation is performed by using a corresponding channel estimation method, the problem of low accuracy of channel estimation is caused. In the embodiment of the application, whether the target path exists in the PDP is detected before channel estimation, so that the current channel environment is judged to obey Rayleigh distribution or Rice distribution, and different channel estimation schemes are adopted for channel estimation, so that the accuracy of channel estimation is improved, and the error rate is reduced.
Optionally, the receiver estimates the doppler spread parameter based on the difference between the maximum and minimum values.
Illustratively, the receiver estimates the doppler spread parameter fd by the following formula:
fd＝(fmax-fmin)/2；
wherein fmax is the maximum value in the frequency offset estimation value of each subframe in the frequency offset change period; fmin is the minimum value in the frequency offset estimation value of each subframe in the frequency offset change period.
Optionally, when there is no target path in the PDP, the receiver uses N effective paths in the PDP of the pilot signal in the current time slot and estimates the doppler spread parameter based on the U-shaped spectrum and the bezier correlation of order 0, where N is a positive integer. And when the target path does not exist in the PDP, determining that the current channel environment obeys Rayleigh distribution, using N effective paths of the pilot signal in the PDP in the current time slot, and estimating a Doppler spread parameter based on the U-shaped spectrum and 0-order Bessel correlation.
To sum up, in the technical solution provided in the embodiment of the present application, after receiving a pilot signal, it is determined whether a current channel environment is compliant with rayleigh distribution based on whether a primary path including a direct path exists in a PDP of multiple timeslots for the pilot signal, and if the primary path including the direct path exists in the PDP, it is determined that the current channel environment is not compliant with rayleigh distribution but compliant with rice distribution, and at this time, a doppler spread parameter is estimated through a maximum value and a minimum value in a frequency offset estimation value of each subframe in a frequency offset change period, so that accuracy of channel estimation is improved, thereby reducing an error rate and improving throughput of a system.
Referring to fig. 3, a flow chart of a channel estimation method according to another embodiment of the present application is shown. The method is also applied to the receiver 12 in fig. 1. The method comprises the following steps:
Step 302, obtain the PDP of the pilot signal.
Step 303, detect whether there is a target path in the PDP.
The target path is the main path including the direct path.
And step 304, when the target diameter exists in the PDP, determining the effective diameter, which is greater than a third threshold value in the number of sampling points of the effective diameters except the target diameter, as the Rayleigh diameter.
The third threshold value is set according to experiments or experience, and is not limited in the embodiments of the present application. Because the direct path has leakage power, the filtering is carried out through the number of the sample points, the phenomenon that the leakage power of the direct path is judged as the Rayleigh path by mistake can be avoided, and the accuracy of a channel estimation result is improved.
Reference is now made in conjunction with fig. 4, which illustrates a schematic diagram of a power delay spectrum according to an embodiment of the present application. In the power time delay spectrum, paths with the number of sampling points from the target path being less than a third threshold value are regarded as invalid rayleigh paths, and paths with the number of sampling points from the target path being greater than or equal to the third threshold value are regarded as valid rayleigh paths.
Step 305, the power of the target path and the power of the rayleigh path are obtained.
And step 306, when the ratio of the power of the target path to the power of the rayleigh path is less than or equal to the second threshold, performing channel estimation based on the rayleigh path to obtain a first estimation value.
The second threshold value is set experimentally or empirically, and is not limited in the embodiments of the present application. When the ratio of the power of the target path to the power of the rayleigh path is smaller than the second threshold, it is indicated that the difference between the power of the main path including the direct path and the power of the rayleigh path is not large, at this time, the target path and the rayleigh path are required to be used for channel estimation respectively, and finally, a final doppler expansion parameter is obtained according to the channel estimation results of the target path and the rayleigh path.
Optionally, the receiver performs channel estimation to obtain the first estimated value by: the receiver carries out channel estimation through a 0-order Bessel function to obtain a first estimation value.
Optionally, the receiver calculates a difference between a maximum value and a minimum value in each subframe in the frequency offset change period; and then determining a second estimated value based on the difference between the maximum value and the minimum value. Illustratively, the receiver performs channel estimation to obtain a second estimated value pshift by the following formula:
Pshift＝(fmax-fmin)/2；
and fmax is the maximum value of the frequency offset estimation value of each subframe of the target path in the frequency offset change period, and fmin is the minimum value of the frequency offset estimation value of each subframe of the fmin target path in the frequency offset change period.
And step 308, estimating a Doppler spread parameter according to the first estimation value and the second estimation value.
Optionally, the receiver determines the doppler spread parameter according to the product parameter between the adjustment factor and the second estimated value and the first estimated value.
The adjustment factor is associated with at least one of: signal to noise ratio, channel delay spread, K factor value. The K factor value is the ratio of the power of the main signal (direct signal) to the variance of the multipath component. Optionally, the receiver stores a corresponding relationship, where the corresponding relationship includes a corresponding relationship between different signal-to-noise ratios, different channel delay spreads, different K factor values, and different adjustment factors, and after obtaining the current signal-to-noise ratio, the current channel delay spread, and the current K factor value, the receiver queries the corresponding relationship, so as to obtain the corresponding adjustment factor.
The product parameter between the adjustment factor and the second estimate is determined based on the product between the adjustment factor and the second estimate. Optionally, the product parameter between the adjustment factor and the second estimation value refers to a product between the adjustment factor and the second estimation value.
Optionally, the receiver obtains a product between the adjustment factor and the second estimated value, and determines a sum of the product and the first estimated value as the doppler spread parameter. The estimation process of the doppler spread parameter is expressed by the following formula:
fd＝fd1+factor*pshift；
wherein, fd1 is the first estimation value, factor is the adjustment factor, pshift is the second estimation value.
When the ratio of the power of the target path to the power of the rayleigh path is greater than the second threshold, it is indicated that the power of the main path including the direct path is stronger, the power of the rayleigh path is weaker, the received signal is mainly the signal propagated by the direct path, and the rayleigh path is ignored at this time, and the target path is directly adopted to estimate the doppler spread parameter. The specific implementation of estimating the doppler spread parameter by using the target path refers to step 304, which is not described herein.
It should be noted that steps 306-308 and step 309 are parallel technical solutions. In one possible implementation, the receiver performs steps 301-308,. In another possible implementation, the receiver performs steps 301-305, 309.
Referring to fig. 5 in combination, when the direct path exists, the position where the frequency offset is 0 after the frequency offset adjustment is close to the position of the direct path, so that the center of gravity of the power spectrum is not located at the center of the U-shaped power spectrum, but located at the position F in fig. 5, the position of the center of gravity of the power spectrum after the frequency offset adjustment is close to the strong power direct path, and if the doppler spread estimation result obtained by performing doppler spread parameter estimation based on the bezier function of order 0 is small. Therefore, in the embodiment of the present application, different channel estimation methods are adopted to perform channel estimation on the target path and the rayleigh path, and finally, the finally estimated doppler spread parameter is determined according to the channel estimation results of the target path and the rayleigh path, so that the accuracy of channel estimation can be improved.
To sum up, in the technical solution provided in the embodiment of the present application, after receiving a pilot signal, it is determined whether a current channel environment is compliant with rayleigh distribution based on whether a primary path including a direct path exists in a PDP of multiple timeslots for the pilot signal, and if the primary path including the direct path exists in the PDP, it is determined that the current channel environment is not compliant with rayleigh distribution but compliant with rice distribution, and at this time, a doppler spread parameter is estimated through a maximum value and a minimum value in a frequency offset estimation value of each subframe in a frequency offset change period, so that accuracy of channel estimation is improved, thereby reducing an error rate and improving throughput of a system.
And when the ratio of the power of the target path to the power of the Rayleigh path is smaller than a second threshold value, different channel estimation methods are adopted to respectively perform channel estimation on the target path and the Rayleigh path, and finally, the finally estimated Doppler expansion parameter is determined according to the channel estimation results of the target path and the Rayleigh path, so that the accuracy of channel estimation can be improved.
And the Rayleigh paths are screened through the number of the sample points, so that the leakage power of the direct path can be prevented from being judged as the Rayleigh paths by mistake, and the accuracy of a channel estimation result is improved.
Referring to fig. 6, a flow chart of a channel estimation method according to an embodiment of the present application is shown. The method comprises the following steps:
Step 605, calculate the PDP in each slot.
And step 609, selecting N effective diameters and M maximum diameters according to the power of each path in the PDP.
And step 610, calculating the signal-to-noise ratios respectively corresponding to the M maximum diameters.
Step 611, calculating variances corresponding to the M maximum diameters according to the signal-to-noise ratios corresponding to the M maximum diameters, respectively.
In step 612, it is determined whether there is a rice path (i.e., a main path including a direct path).
When it is determined that the rice path exists, step 614-620 is executed, and when it is determined that the rice path does not exist, step 613 is executed.
Step 614, distinguish between the rice path and the rayleigh path.
When the ratio is greater than the second threshold, step 617 is performed, and when the ratio is less than or equal to the second threshold, step 618 and step 620 are performed.
At step 618, a first estimate is obtained using the rayleigh path.
And step 620, acquiring the finally estimated Doppler spread parameter according to the first estimation value and the second estimation value.
In the following, embodiments of the apparatus of the present application are described, and for portions of the embodiments of the apparatus not described in detail, reference may be made to technical details disclosed in the above-mentioned method embodiments.
Referring to fig. 7, a block diagram of a receiver provided in an exemplary embodiment of the present application is shown. The receiver may be implemented as all or part of a terminal, in software, hardware, or a combination of both. The receiver includes: a receiving unit 701 and a processing unit 702.
The receiving unit 701 is configured to receive a pilot signal.
The processing unit 702 is configured to:
acquiring a power time delay spectrum PDP of the pilot signal;
detecting whether a target path exists in the PDP, wherein the target path is a main path comprising a direct path;
and when the target diameter exists in the PDP, determining Doppler spread parameters according to the maximum value and the minimum value in the frequency offset estimation values of all subframes in the frequency offset change period.
To sum up, in the technical solution provided in the embodiment of the present application, after receiving a pilot signal, it is determined whether a current channel environment is compliant with rayleigh distribution based on whether a primary path including a direct path exists in a PDP of multiple timeslots for the pilot signal, and if the primary path including the direct path exists in the PDP, it is determined that the current channel environment is not compliant with rayleigh distribution but compliant with rice distribution, and at this time, a doppler spread parameter is estimated through a maximum value and a minimum value in a frequency offset estimation value of each subframe in a frequency offset change period, so that accuracy of channel estimation is improved, thereby reducing an error rate and improving throughput of a system.
In an alternative embodiment provided based on the embodiment shown in fig. 7, the processing unit 702 is configured to:
selecting M maximum paths from the PDP according to the power of the paths included by the PDP, wherein M is a positive integer;
acquiring signal-to-noise ratio parameters corresponding to the M maximum diameters according to the signal-to-noise ratios corresponding to the M maximum diameters respectively;
and detecting whether the target path exists in the PDP according to the signal-to-noise ratio parameters corresponding to the M maximum paths.
Optionally, the processing unit 702 is configured to:
acquiring signal-to-noise ratio variances corresponding to the M maximum diameters according to the signal-to-noise ratios corresponding to the M maximum diameters respectively;
and detecting whether the target path exists in the PDP according to the signal-to-noise ratio variance corresponding to the M maximum paths.
Optionally, the processing unit 702 is configured to:
when the signal-to-noise ratio variance corresponding to the M maximum paths is smaller than a first threshold value, determining that the target path exists in the PDP;
and when the signal-to-noise ratio variance corresponding to the M maximum paths is larger than or equal to the first threshold value, determining that the target path does not exist in the PDP.
In an alternative embodiment provided based on the embodiment shown in fig. 7, the processing unit 702 is configured to:
and determining the Doppler spread parameter according to the difference value between the maximum value and the minimum value.
In an alternative embodiment provided based on the embodiment shown in fig. 7, the processing unit 702 is configured to:
when the target path exists in the PDP, acquiring the power of the target path and the power of a Rayleigh path;
and when the ratio of the power of the target path to the power of the Rayleigh path is greater than a second threshold value, executing the step of determining Doppler expansion parameters according to the maximum value and the minimum value in the frequency offset estimation value of each subframe in the frequency offset change period.
Optionally, the processing unit 702 is further configured to:
when the ratio of the power of the target path to the power of the Rayleigh path is smaller than or equal to the second threshold value, performing channel estimation by using the Rayleigh path based on a U-shaped spectrum and a 0-order Bessel function to obtain a first estimation value;
determining a second estimated value based on the maximum value and the minimum value of the frequency deviation estimated values of the target path in each subframe in the frequency deviation change period;
and determining the Doppler spread parameter according to the first estimation value and the second estimation value.
Optionally, the processing unit 702 is configured to:
determining the Doppler spread parameter based on a product parameter between an adjustment factor and the second estimated value and the first estimated value;
wherein the adjustment factor is associated with at least one of: signal to noise ratio, channel delay spread, K factor value. Optionally, the processing unit 702 is configured to:
obtaining a product between the adjustment factor and the second estimation value;
determining a sum of the product and the first estimate as the Doppler spread parameter.
Optionally, the processing unit 702 is further configured to: and when the target diameter exists in the PDP, determining the effective diameter, which is greater than a third threshold value in the number of sampling points of the effective diameters except the target diameter, from the target diameter as the Rayleigh diameter.
In an optional embodiment provided based on the embodiment shown in fig. 7, the processing unit 702 is further configured to: and when the target path does not exist in the PDP, estimating the Doppler spread parameter by using N effective paths of the pilot signal in the PDP of the current time slot based on a U-shaped spectrum and a 0-order Bessel function, wherein N is an integer larger than M.
It should be noted that, when the apparatus provided in the foregoing embodiment implements the functions thereof, only the division of the functional modules is illustrated, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the internal structure of the apparatus may be divided into different functional modules to implement all or part of the functions described above. In addition, the apparatus and method embodiments provided by the above embodiments belong to the same concept, and specific implementation processes thereof are described in the method embodiments for details, which are not described herein again.
Fig. 8 is a block diagram of a terminal according to an example embodiment.
The terminal 800 includes a transmitter 801, a receiver 802, and a processor 803. The processor 803 may be a controller, and is shown in fig. 8 as "controller/processor 803". Optionally, the terminal 800 may further include a modem processor 805, wherein the modem processor 805 may include an encoder 806, a modulator 807, a decoder 808, and a demodulator 809.
In one example, the transmitter 801 conditions (e.g., converts to analog, filters, amplifies, and frequency upconverts, etc.) the output samples and generates an uplink signal, which is transmitted via an antenna to the access network equipment described in the embodiments above. On the downlink, the antenna receives the downlink signal transmitted by the access network device in the above embodiment. Receiver 802 conditions (e.g., filters, amplifies, downconverts, and digitizes, etc.) the received signal from the antenna and provides input samples. In modem processor 805, an encoder 806 receives traffic data and signaling messages to be sent on the uplink and processes (e.g., formats, encodes, and interleaves) the traffic data and signaling messages. A modulator 807 further processes (e.g., symbol maps and modulates) the coded traffic data and signaling messages and provides output samples. A demodulator 809 processes (e.g., demodulates) the input samples and provides symbol estimates. A decoder 808 processes (e.g., deinterleaves and decodes) the symbol estimates and provides decoded data and signaling messages for transmission to terminal 800. Encoder 806, modulator 807, demodulator 809, and decoder 808 may be implemented by a combined modem processor 805. These elements are processed in accordance with the radio access technology employed by the radio access network (e.g., the access technologies of LTE and other evolved systems). It is noted that when terminal 800 does not include modem 805, the above-described functions of modem 805 can also be performed by processor 803.
The processor 803 controls and manages the operation of the terminal 800, and is used for executing the processing procedures performed by the terminal 800 in the embodiments of the present disclosure. For example, the processor 803 is further configured to perform various steps of the terminal side in the above-described method embodiments, and/or other steps of the technical solutions described in the embodiments of the present disclosure.
Further, the terminal 800 can also include a memory 804, the memory 804 being used to store program codes and data for the terminal 800.
Those skilled in the art will appreciate that the configuration shown in fig. 8 is not intended to be limiting of terminal 800 and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components may be used.
In an exemplary embodiment, a computer-readable storage medium is also provided, in which a computer program is stored, which is loaded and executed by a processor of a terminal to implement the channel estimation method in the above-described method embodiments.
Alternatively, the computer-readable storage medium may be a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic tape, a floppy disk, an optical data storage device, and the like.
In an exemplary embodiment, a computer program product is also provided, which includes computer instructions stored in a computer-readable storage medium, which are read by a processor of a computer device from the computer-readable storage medium, and the processor executes the computer instructions to make the computer device execute the channel estimation method provided in the foregoing one aspect or various optional implementations of the one aspect.
It should be understood that reference to "a plurality" herein means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. As used herein, the terms "first," "second," and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.
The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
The above description is only exemplary of the present application and should not be taken as limiting the present application, and any modifications, equivalents, improvements and the like that are made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (14)
1. A method of channel estimation, the method comprising:
receiving a pilot signal;
acquiring a power time delay spectrum PDP of the pilot signal;
detecting whether a target path exists in the PDP, wherein the target path is a main path comprising a direct path;
and when the target diameter exists in the PDP, determining Doppler spread parameters according to the maximum value and the minimum value in the frequency offset estimation values of all subframes in the frequency offset change period.
2. The method of claim 1, wherein said detecting whether a target path is present in said PDP comprises:
selecting M maximum paths from the PDP according to the power of the paths included by the PDP, wherein M is a positive integer;
acquiring signal-to-noise ratio parameters corresponding to the M maximum diameters according to the signal-to-noise ratios corresponding to the M maximum diameters respectively;
and detecting whether the target path exists in the PDP according to the signal-to-noise ratio parameters corresponding to the M maximum paths.
3. The method of claim 2,
the acquiring signal-to-noise ratio parameters corresponding to the M maximum diameters according to the signal-to-noise ratios corresponding to the M maximum diameters respectively comprises: acquiring signal-to-noise ratio variances corresponding to the M maximum diameters according to the signal-to-noise ratios corresponding to the M maximum diameters respectively;
the detecting whether the target path exists in the PDP according to the signal-to-noise ratio parameters corresponding to the M maximum paths includes: and detecting whether the target path exists in the PDP according to the signal-to-noise ratio variance corresponding to the M maximum paths.
4. The method according to claim 3, wherein said detecting whether the target path exists in the PDP according to the SNR variance corresponding to the M maximum paths comprises:
when the signal-to-noise ratio variance corresponding to the M maximum paths is smaller than a first threshold value, determining that the target path exists in the PDP;
and when the signal-to-noise ratio variance corresponding to the M maximum paths is larger than or equal to the first threshold value, determining that the target path does not exist in the PDP.
5. The method of claim 1, wherein determining the doppler spread parameter according to the maximum value and the minimum value of the frequency offset estimation values of the subframes in the frequency offset variation period comprises:
and determining the Doppler spread parameter according to the difference value between the maximum value and the minimum value.
6. The method of claim 1, wherein before determining the doppler spread parameter according to the maximum value and the minimum value of the frequency offset estimation values of the subframes in the frequency offset variation period, the method further comprises:
when the target path exists in the PDP, acquiring the power of the target path and the power of a Rayleigh path;
and when the ratio of the power of the target path to the power of the Rayleigh path is greater than a second threshold value, executing the step of determining Doppler expansion parameters according to the maximum value and the minimum value in the frequency offset estimation value of each subframe in the frequency offset change period.
7. The method of claim 6, further comprising:
when the ratio of the power of the target path to the power of the Rayleigh path is smaller than or equal to the second threshold value, performing channel estimation by using the Rayleigh path based on a U-shaped spectrum and a 0-order Bessel function to obtain a first estimation value;
determining a second estimated value based on the maximum value and the minimum value of the frequency deviation estimated values of the target path in each subframe in the frequency deviation change period;
and determining the Doppler spread parameter according to the first estimation value and the second estimation value.
8. The method of claim 7, wherein estimating the doppler spread parameter from the first estimate and the second estimate comprises:
determining the Doppler spread parameter based on a product parameter between an adjustment factor and the second estimated value and the first estimated value;
wherein the adjustment factor is associated with at least one of: signal to noise ratio, channel delay spread, K factor value.
9. The method of claim 8, wherein,
obtaining a product between the adjustment factor and the second estimation value;
determining a sum of the product and the first estimate as the Doppler spread parameter.
10. The method according to any one of claims 6-9, wherein before obtaining the power of the target path and the power of the rayleigh path, further comprising:
and when the target diameter exists in the PDP, determining the effective diameter, which is greater than a third threshold value in the number of sampling points of the effective diameters except the target diameter, from the target diameter as the Rayleigh diameter.
11. The method according to any one of claims 1 to 9, further comprising:
and when the target path does not exist in the PDP, using N effective paths of the pilot signal in the PDP of the current time slot, and determining the Doppler spread parameter based on a U-shaped spectrum and a 0-order Bessel function, wherein N is an integer larger than M.
12. A receiver, characterized in that the receiver comprises
A receiving unit for receiving a pilot signal;
a processing unit to:
acquiring a power time delay spectrum PDP of the pilot signal;
detecting whether a target path exists in the PDP, wherein the target path is a main path comprising a direct path;
and when the target diameter exists in the PDP, determining Doppler spread parameters according to the maximum value and the minimum value in the frequency offset estimation values of all subframes in the frequency offset change period.
13. A receiver, characterized in that the receiver comprises a processor and a memory, the memory storing a computer program which is loaded and executed by the processor to implement the channel estimation method according to any of claims 1 to 11.
14. A computer-readable storage medium, in which a computer program is stored which is loaded and executed by a processor to implement the channel estimation method according to any one of claims 1 to 11.
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