CN106921450B - Signal-to-noise ratio estimation method and device - Google Patents
Signal-to-noise ratio estimation method and device Download PDFInfo
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Abstract
The application provides a method and a device for estimating a signal-to-noise ratio, which are used for improving the accuracy of the signal-to-noise ratio estimation. The embodiment of the application provides a signal-to-noise ratio estimation method, which comprises the following steps: determining frequency domain data of a pilot frequency symbol of a currently received OFDM symbol and frequency domain data of a pilot frequency symbol of an OFDM symbol adjacent to the OFDM symbol; determining the average value of channel responses of the currently received OFDM symbol and OFDM symbols adjacent to the currently received OFDM symbol by using the frequency domain data, and determining the noise power of the currently received OFDM symbol according to the average value of the channel responses; and determining the signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol.
Description
Technical Field
The present application relates to the field of communications technologies, and in particular, to a signal-to-noise ratio estimation method and apparatus.
Background
In an Orthogonal Frequency Division Multiplexing (OFDM) system, in order to correctly demodulate data, a receiving end needs to be able to accurately estimate a signal-to-noise ratio, and whether the signal-to-noise ratio estimation is accurate, which directly affects the performance of an equalization module and a channel decoding module.
In the method for estimating the signal-to-noise ratio in the prior art, the accuracy of the signal-to-noise ratio estimation is sensitive to frequency offset, and the accuracy of the signal-to-noise ratio estimation is reduced after the input signal is superposed with the frequency offset with certain frequency. The more frequency offset, the more the accuracy of the signal-to-noise ratio estimate degrades.
In summary, the snr estimation method in the prior art has a low snr estimation accuracy.
Disclosure of Invention
The embodiment of the application provides a method and a device for estimating a signal-to-noise ratio, which are used for improving the accuracy of the signal-to-noise ratio estimation.
The embodiment of the application provides a signal-to-noise ratio estimation method, which comprises the following steps:
determining frequency domain data of a pilot frequency symbol of a currently received OFDM symbol and frequency domain data of a pilot frequency symbol of an OFDM symbol adjacent to the OFDM symbol;
determining the average value of the channel response of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol by using the frequency domain data, and determining the noise power of the currently received OFDM symbol according to the average value of the channel response;
and determining the signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol.
The signal-to-noise ratio estimation method provided by the embodiment of the application determines the channel response average value of the adjacent OFDM symbols by determining the frequency domain data of the pilot symbols of the adjacent OFDM symbols, determines the noise power of the currently received OFDM symbols according to the channel response average value, and further determines the signal-to-noise ratio of the OFDM symbols by using the noise power of the OFDM symbols, so that the influence of frequency deviation on the signal-to-noise ratio estimation can be resisted, and the signal-to-noise ratio estimation accuracy can be improved.
Preferably, determining the frequency domain data of the pilot symbol of the currently received OFDM symbol specifically includes:
preprocessing a currently received OFDM symbol to obtain baseband frequency domain data of the currently received OFDM symbol; determining frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol.
Preferably, the preprocessing the data of the currently received OFDM symbol to obtain the baseband frequency domain data of the currently received OFDM symbol specifically includes:
performing fast Fourier transform on the time domain data of the currently received OFDM symbol according to the following formula to obtain baseband frequency domain data of the currently received OFDM symbol:
wherein, YkIs the frequency domain data, y, on the k +1 th subcarrier of the currently received OFDM symbolnThe time domain data of the N +1 th subcarrier of the currently received OFDM symbol is represented by N, the number of the subcarriers is represented by N, j is an imaginary unit, the baseband frequency domain data of the currently received OFDM symbol comprises frequency domain data of the N subcarriers, and the frequency domain data of part of the frequency domain data of the N subcarriers is the frequency domain data of the pilot frequency symbol.
Preferably, the determining the frequency domain data of the pilot symbol of the currently received OFDM symbol from the baseband frequency domain data of the currently received OFDM symbol specifically includes: and determining the frequency domain data of the pilot frequency symbol of the currently received OFDM symbol according to the preset serial numbers of the partial subcarriers.
Preferably, the channel response average value of the currently received OFDM symbol and OFDM symbols adjacent to the currently received OFDM symbol is determined by the following formula:
wherein the content of the first and second substances,
is the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the OFDM symbol,
is the conjugate of the frequency domain data of the pilot symbols of the predetermined pilot sequence on the l +1 th subcarrier, Y1，lFrequency domain data of pilot symbols of the currently received OFDM symbols on the (l + 1) th subcarrier, Y0，lAnd M is the frequency domain data of pilot symbols of OFDM symbols adjacent to the currently received OFDM symbol on the (l + 1) th subcarrier, and is the serial number set of the partial subcarriers.
Preferably, the noise power of the currently received OFDM symbol is calculated by the following formula
Wherein the content of the first and second substances,
for the currently received OFDM symbol noise power,
for the currently received OFDM symbol and the OFDM symbolThe conjugate of the mean value of the channel responses on the (l + 1) th sub-carrier of the adjacent OFDM symbol, P being the number of pilot symbols in said currently received OFDM symbol,
and taking the imaginary part as the modulus of the average value of the channel responses on the l +1 th subcarrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, wherein Im represents.
The embodiment of the application provides a signal-to-noise ratio estimation device, which comprises:
a first unit, configured to determine frequency domain data of a pilot symbol of a currently received OFDM symbol and frequency domain data of a pilot symbol of an OFDM symbol adjacent to the OFDM symbol;
a second unit, configured to determine, by using the frequency domain data, a channel response average value of the currently received OFDM symbol and an OFDM symbol adjacent to the currently received OFDM symbol, and determine, according to the channel response average value, a noise power of the currently received OFDM symbol;
a third unit, configured to determine a signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol.
Preferably, the determining, by the first unit, frequency domain data of a pilot symbol of a currently received OFDM symbol specifically includes:
preprocessing a currently received OFDM symbol to obtain baseband frequency domain data of the currently received OFDM symbol; determining frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol.
Preferably, the preprocessing the data of the currently received OFDM symbol by the first unit to obtain the baseband frequency domain data of the currently received OFDM symbol specifically includes:
performing fast Fourier transform on the time domain data of the currently received OFDM symbol by using the following formula to obtain baseband frequency domain data of the currently received OFDM symbol:
wherein, YkIs the frequency domain data, y, on the k +1 th subcarrier of the currently received OFDM symbolnThe time domain data of the N +1 th subcarrier of the currently received OFDM symbol is represented by N, the number of the subcarriers is represented by N, j is an imaginary unit, the baseband frequency domain data of the currently received OFDM symbol comprises frequency domain data of the N subcarriers, and the frequency domain data of part of the frequency domain data of the N subcarriers is the frequency domain data of the pilot frequency symbol.
Preferably, the determining, by the first unit, frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol specifically includes: and determining the frequency domain data of the pilot frequency symbol of the currently received OFDM symbol according to the preset serial numbers of the partial subcarriers.
Preferably, the second unit determines the average value of the channel responses of the currently received OFDM symbol and OFDM symbols adjacent to the currently received OFDM symbol by using the following formula:
wherein the content of the first and second substances,
is the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the OFDM symbol,
is the conjugate of the frequency domain data of the pilot symbols of the predetermined pilot sequence on the l +1 th subcarrier, Y1，lFrequency domain data of pilot symbols of the currently received OFDM symbols on the (l + 1) th subcarrier, Y0，lAnd M is the frequency domain data of pilot symbols of OFDM symbols adjacent to the currently received OFDM symbol on the (l + 1) th subcarrier, and is the serial number set of the partial subcarriers.
Preferably, the second unit calculates the noise power of the currently received OFDM symbol by using the following formula:
wherein the content of the first and second substances,
for the currently received OFDM symbol noise power,
is the conjugate of the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, P is the number of pilot symbols in the currently received OFDM symbol,
and taking the imaginary part as the modulus of the average value of the channel responses on the l +1 th subcarrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, wherein Im represents.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic flow chart of a signal-to-noise ratio estimation method according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of an snr estimation apparatus according to an embodiment of the present disclosure.
Detailed Description
The embodiment of the application provides a method and a device for estimating a signal-to-noise ratio, which are used for improving the accuracy of the signal-to-noise ratio estimation.
As shown in fig. 1, a method for estimating a signal-to-noise ratio provided in an embodiment of the present application includes:
s101, determining frequency domain data of a pilot frequency symbol of a currently received OFDM symbol and frequency domain data of a pilot frequency symbol of an OFDM symbol adjacent to the OFDM symbol;
s102, determining the average value of the channel response of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol by using the frequency domain data, and determining the noise power of the currently received OFDM symbol according to the average value of the channel response;
s103, determining the signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol.
The signal-to-noise ratio estimation method provided by the embodiment of the application determines the channel response average value of the adjacent OFDM symbol by determining the frequency domain data of the pilot frequency symbol of the adjacent OFDM symbol, determines the noise power of the currently received OFDM symbol according to the channel response average value, and further determines the signal-to-noise ratio of the currently received OFDM symbol by using the noise power of the currently received OFDM symbol, so that the influence of frequency deviation on the signal-to-noise ratio estimation can be resisted, and the signal-to-noise ratio estimation accuracy is improved.
Preferably, in step S101, determining frequency domain data of a pilot symbol of a currently received OFDM symbol specifically includes:
preprocessing a currently received OFDM symbol to obtain baseband frequency domain data of the currently received OFDM symbol; determining frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol.
The baseband frequency domain data refers to frequency domain data of the OFDM symbol when the subcarrier frequency of the OFDM symbol is 0 Hz.
Preferably, the preprocessing the received data of the OFDM symbol to obtain the baseband frequency domain data of the OFDM symbol specifically includes:
performing Fast Fourier Transform (FFT) on the time-domain data of the currently received OFDM symbol to obtain baseband frequency-domain data of the currently received OFDM symbol according to the following formula:
wherein, YkIs the frequency domain data, y, on the k +1 th subcarrier of the currently received OFDM symbolnThe time domain data of the N +1 th subcarrier of the currently received OFDM symbol is represented by N, the number of the subcarriers is represented by N, j is an imaginary unit, the baseband frequency domain data of the currently received OFDM symbol comprises frequency domain data of the N subcarriers, and the frequency domain data of part of the frequency domain data of the N subcarriers is the frequency domain data of the pilot frequency symbol.
Preferably, determining the frequency domain data of the pilot symbol of the OFDM symbol from the baseband frequency domain data of the OFDM symbol specifically includes: and determining the frequency domain data of the pilot frequency symbol of the currently received OFDM symbol according to the preset serial numbers of the partial subcarriers.
It should be noted that the baseband frequency-domain data of one OFDM symbol includes both the frequency-domain data of the effective data and the frequency-domain data of the pilot symbol. And the preset serial numbers of the part of subcarriers are determined according to the serial numbers of the subcarriers corresponding to the pilot symbols in the preset pilot sequence. The preset pilot sequence, that is, the known pilot sequence stored by the transmitting end and the receiving end, in the initial signal sent by the transmitting end, information of the pilot sequence, for example, the serial number of a part of subcarriers corresponding to the pilot symbol in the OFDM symbol and the frequency domain data of the pilot symbol, is known to both the transmitting end and the receiving end, and the serial number of the pilot symbol in the OFDM symbol is fixed.
Due to the existence of noise, the frequency domain data Y of the pilot frequency symbol on the l +1 th subcarrier in the OFDM symbol currently receivedlCan be expressed as
Yl＝HlCl+Jl，l∈M；
Wherein HlIs the channel response on the l +1 sub-carrier of the currently received OFDM symbol, ClFor a predetermined guideFrequency domain data of pilot symbols of a frequency sequence on the (l + 1) th subcarrier, JlFor noise on the l +1 th subcarrier, M is the number set of the partial subcarriers, i.e., M is [0, N-1 ]]A subset of (a).
It should be noted that, in each OFDM symbol, the frequency domain data C of the pilot symbol of the preset pilot sequence on the l +1 th subcarrierlAre the same.
The signal-to-noise ratio estimation method provided by the embodiment of the present application is described by taking the received 1 st OFDM symbol and 2 nd OFDM symbol as examples. Wherein, the 2 nd OFDM symbol is the OFDM symbol currently received, noise is ignored, and the channel response on the l sub-carrier of the 1 st OFDM symbol is
The channel response on the l sub-carrier of the 2 nd OFDM symbol is
Wherein, Y0，lFrequency domain data on the l +1 sub-carrier of the pilot symbol representing the 1 st OFDM symbol, Y1,kFrequency domain data of pilot symbols representing the 2 nd OFDM symbol on the l +1 th subcarrier.
The energy of the pilot symbols being 1, i.e.
The channel responses of the 1 st OFDM symbol and the 2 nd OFDM symbol on the l +1 th subcarrier can be expressed as
And
then the average of the channel responses of the 1 st OFDM symbol and the 2 nd OFDM symbol on the l +1 th subcarrier is:
wherein the content of the first and second substances,
is the average value of the channel responses of the 1 st OFDM symbol and the 2 nd OFDM symbol on the l +1 th subcarrier,
the conjugate of the frequency domain data of the preset pilot frequency sequence on the l +1 th subcarrier.
It should be noted that, with the method for estimating signal-to-noise ratio provided in this embodiment of the present application, it may also be possible to determine frequency domain data of pilot symbols of a plurality of adjacent OFDM symbols to determine a channel response average value of the plurality of OFDM symbols on the (l + 1) th subcarrier, for example, it may be possible to determine frequency domain data Y of pilot symbols of three adjacent OFDM symbols on the (l + 1) th subcarrieri，l、Yi+1，l、Yi+2，lWherein Y isi+2，lFor the frequency domain data of the pilot symbol of the currently received OFDM symbol on the (l + 1) th subcarrier, i may be taken from 0, in which case Y0，lThe frequency domain data i representing the pilot symbol of the first received OFDM symbol on the (l + 1) th subcarrier can also be taken from 1, in which case Y1，lFrequency domain data on the l +1 th subcarrier of the pilot symbol representing the first received OFDM symbol.
Preferably, the noise power of the currently received OFDM symbol, i.e. the 2 nd OFDM symbol, is determined by the following formula:
wherein the content of the first and second substances,
for the 2 nd OFDM symbol noise power,
is the 1 st OFDM symbolThe conjugate of the number and the average of the channel response on the l +1 th subcarrier of the 2 nd OFDM symbol, P is the number of pilot symbols in the 2 nd OFDM symbol,
the modulus of the channel response average value on the l +1 th sub-carrier of the 1 st OFDM symbol and the 2 nd OFDM symbol is represented by Im, which is taken as the imaginary part.
Preferably, determining the signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol, that is, the 2 nd OFDM symbol specifically includes:
according to the baseband frequency domain data of the 2 nd OFDM symbol, determining the average power of the currently received OFDM symbol as:
according to the average power of the 2 nd OFDM symbol and the noise power of the 2 nd OFDM symbol, determining the signal power of the 2 nd OFDM symbol as:
determining the ratio of the signal power of the 2 nd OFDM symbol to the noise power of the 2 nd OFDM symbol as:
where SNR is the signal-to-noise ratio of the 2 nd OFDM symbol.
The signal-to-noise ratio estimation method provided by the embodiment of the present application is applied to the 802.16d communication standard, and when the number of subcarriers N is 1024 and 50kHz frequency offset is superimposed in a channel, the Normalized Mean Square Error (NMSE) of the signal-to-noise ratio estimation method provided by the embodiment of the present application may reach 10-4Order of magnitude, whereas the NMSE of the SNR estimate obtained in the prior art is 10-2Magnitude order, it can be seen that the signal-to-noise ratio estimation method provided by the embodiment of the application has frequency resistanceDue to the characteristic of deviation, under the condition that frequency deviation exists, the accuracy of signal-to-noise ratio estimation is higher than that of the prior art. Wherein the formula for NMSE is:
wherein
Representing the noise power value obtained by calculation, X representing the actual value of the noise power, the smaller the NMSE, the more accurate the noise power estimate.
Corresponding to the signal-to-noise ratio estimation method provided by the embodiment of the present application, the embodiment of the present application further provides a signal-to-noise ratio estimation apparatus, as shown in fig. 2, the apparatus includes:
a first unit 201, configured to determine frequency domain data of a pilot symbol of a currently received OFDM symbol and frequency domain data of a pilot symbol of an OFDM symbol adjacent to the OFDM symbol;
a second unit 202, configured to determine, by using the frequency domain data, a channel response average value of the currently received OFDM symbol and an OFDM symbol adjacent to the currently received OFDM symbol, and determine, according to the channel response average value, a noise power of the currently received OFDM symbol;
a third unit 203, configured to determine a signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol.
The signal-to-noise ratio estimation device provided by the embodiment of the application determines the channel response average value of the adjacent OFDM symbol by determining the frequency domain data of the pilot frequency symbol of the adjacent OFDM symbol, determines the noise power of the currently received OFDM symbol according to the channel response average value, and further determines the signal-to-noise ratio of the OFDM symbol by using the noise power of the OFDM symbol, so that the influence of frequency deviation on the signal-to-noise ratio estimation can be resisted, and the signal-to-noise ratio estimation accuracy is improved.
Preferably, the determining, by the first unit 201, frequency domain data of a pilot symbol of a currently received OFDM symbol specifically includes:
preprocessing a currently received OFDM symbol to obtain baseband frequency domain data of the currently received OFDM symbol; determining frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol.
Preferably, the preprocessing the data of the currently received OFDM symbol by the first unit 201, and obtaining the baseband frequency domain data of the currently received OFDM symbol specifically includes:
performing fast Fourier transform on the time domain data of the currently received OFDM symbol according to the following formula to obtain baseband frequency domain data of the currently received OFDM symbol:
wherein, YkIs the frequency domain data, y, on the k +1 th subcarrier of the currently received OFDM symbolnThe time domain data of the N +1 th subcarrier of the currently received OFDM symbol is represented by N, the number of the subcarriers is represented by N, j is an imaginary unit, the baseband frequency domain data of the currently received OFDM symbol comprises frequency domain data of the N subcarriers, and the frequency domain data of part of the frequency domain data of the N subcarriers is the frequency domain data of the pilot frequency symbol.
Preferably, the determining, by the first unit 201, frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol specifically includes: and determining the frequency domain data of the pilot frequency symbol of the currently received OFDM symbol according to the preset serial numbers of the partial subcarriers.
Preferably, the second unit 202 determines the average value of the channel responses of the currently received OFDM symbol and OFDM symbols adjacent to the currently received OFDM symbol by using the following formula:
wherein the content of the first and second substances,
is the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the OFDM symbol,
is the conjugate of the frequency domain data of the pilot symbols of the predetermined pilot sequence on the l +1 th subcarrier, Y1，lFrequency domain data of pilot symbols of the currently received OFDM symbols on the (l + 1) th subcarrier, Y0，lAnd M is the frequency domain data of pilot symbols of OFDM symbols adjacent to the currently received OFDM symbol on the (l + 1) th subcarrier, and is the serial number set of the partial subcarriers.
Preferably, the second unit 202 determines the noise power of the currently received OFDM symbol by using the following formula
Wherein the content of the first and second substances,
for the currently received OFDM symbol noise power,
is the conjugate of the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, P is the number of pilot symbols in the currently received OFDM symbol,
and taking the imaginary part as the modulus of the average value of the channel responses on the l +1 th subcarrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, wherein Im represents.
Preferably, the third unit 203 is specifically configured to:
according to the baseband frequency domain data of the currently received OFDM symbol, determining that the average power of the currently received OFDM symbol is:
determining the signal power of the currently received OFDM symbol as follows according to the average power of the currently received OFDM symbol and the noise power of the currently received OFDM symbol:
determining a ratio of a signal power of the currently received OFDM symbol and a noise power of the currently received OFDM symbol as
Wherein the SNR is a signal-to-noise ratio of the currently received OFDM symbol.
In summary, the signal-to-noise ratio estimation method and device provided in the embodiment of the present application determine the frequency domain data of the pilot symbol of the adjacent OFDM symbol, determine the channel response average value of the adjacent OFDM symbol, determine the noise power of the currently received OFDM symbol according to the channel response average value, further determine the signal-to-noise ratio of the OFDM symbol by using the noise power of the OFDM symbol, and can resist the influence of the frequency offset on the signal-to-noise ratio estimation, thereby improving the accuracy of the signal-to-noise ratio estimation.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (10)
1. A method for estimating a signal-to-noise ratio, the method comprising:
determining frequency domain data of a pilot frequency symbol of a currently received Orthogonal Frequency Division Multiplexing (OFDM) symbol and frequency domain data of a pilot frequency symbol of an OFDM symbol adjacent to the OFDM symbol;
determining the average value of the channel response of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol by using the frequency domain data, and determining the noise power of the currently received OFDM symbol by adopting the following formula according to the average value of the channel response:
wherein the content of the first and second substances,
for said currently received OFDM symbol noise power, Y1,lFrequency domain data on the l +1 th subcarrier for the pilot symbol of the currently received OFDM symbol,
is the conjugate of the frequency domain data of the pilot symbol of the preset pilot sequence on the (l + 1) th subcarrier,
is the conjugate of the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, P is the number of pilot symbols in the currently received OFDM symbol,
taking the imaginary part as the module of the average value of the channel responses on the (l + 1) th subcarrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, wherein Im represents;
and determining the signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol.
2. The method of claim 1, wherein determining frequency domain data for pilot symbols of a currently received OFDM symbol comprises:
preprocessing a currently received OFDM symbol to obtain baseband frequency domain data of the currently received OFDM symbol;
determining frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol.
3. The method according to claim 2, wherein preprocessing a currently received OFDM symbol to obtain baseband frequency-domain data of the currently received OFDM symbol specifically comprises:
performing fast fourier transform on the time domain data of the currently received OFDM symbol by using the following formula to obtain baseband frequency domain data of the currently received OFDM symbol:
wherein, YkIs the frequency domain data, y, on the k +1 th subcarrier of the currently received OFDM symbolnThe time domain data of the N +1 th subcarrier of the currently received OFDM symbol is represented by N, the number of the subcarriers is represented by N, j is an imaginary unit, the baseband frequency domain data of the currently received OFDM symbol comprises frequency domain data of the N subcarriers, and the frequency domain data of part of the frequency domain data of the N subcarriers is the frequency domain data of the pilot frequency symbol.
4. The method according to claim 3, wherein determining frequency domain data for pilot symbols of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol specifically comprises: and determining the frequency domain data of the pilot frequency symbol of the currently received OFDM symbol according to the preset serial numbers of the partial subcarriers.
5. The method of claim 4, wherein the average value of the channel responses of the currently received OFDM symbol and OFDM symbols adjacent to the currently received OFDM symbol is determined by using the following formula:
wherein the content of the first and second substances,
is the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the OFDM symbol, Y0,lAnd M is the frequency domain data of pilot symbols of OFDM symbols adjacent to the currently received OFDM symbol on the (l + 1) th subcarrier, and is the serial number set of the partial subcarriers.
6. A signal-to-noise ratio estimation apparatus, comprising:
a first unit, configured to determine frequency domain data of a pilot symbol of a currently received OFDM symbol and frequency domain data of a pilot symbol of an OFDM symbol adjacent to the OFDM symbol;
a second unit, configured to determine, by using the frequency domain data, a channel response average value of the currently received OFDM symbol and an OFDM symbol adjacent to the currently received OFDM symbol, and determine, according to the channel response average value, a noise power of the currently received OFDM symbol by using the following formula:
wherein the content of the first and second substances,
for the currently received OFDM symbol noise power,
is the conjugate of the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, and P is the pilot symbol in the currently received OFDM symbolThe number of the numbers is equal to or greater than the number of the numbers,
taking the imaginary part as the module of the average value of the channel responses on the (l + 1) th subcarrier of the currently received OFDM symbol and the OFDM symbol adjacent to the currently received OFDM symbol, wherein Im represents;
a third unit, configured to determine a signal-to-noise ratio of the currently received OFDM symbol according to the noise power of the currently received OFDM symbol.
7. The apparatus as claimed in claim 6, wherein the determining, by the first unit, frequency domain data of pilot symbols of a currently received OFDM symbol specifically comprises:
preprocessing data of a currently received OFDM symbol to obtain baseband frequency domain data of the currently received OFDM symbol;
determining frequency domain data of a pilot symbol of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol.
8. The apparatus according to claim 7, wherein the first unit, performing preprocessing on the currently received OFDM symbol to obtain baseband frequency-domain data of the currently received OFDM symbol, specifically comprises:
performing fast Fourier transform on the time domain data of the currently received OFDM symbol by using the following formula to obtain baseband frequency domain data of the currently received OFDM symbol:
wherein, YkIs the frequency domain data, y, on the k +1 th subcarrier of the currently received OFDM symbolnThe time domain data of the N +1 th subcarrier of the currently received OFDM symbol is obtained, N is the number of subcarriers, j is an imaginary unit, the baseband frequency domain data of the currently received OFDM symbol comprises frequency domain data of the N subcarriers, and the N frequency domain data are frequency domain data of the N subcarriersThe frequency domain data on a part of the subcarriers in the frequency domain data on the subcarriers is the frequency domain data of the pilot symbols.
9. The apparatus as claimed in claim 8, wherein the determining, by the first unit, frequency domain data of pilot symbols of the currently received OFDM symbol from baseband frequency domain data of the currently received OFDM symbol specifically comprises: and determining the frequency domain data of the pilot frequency symbol of the currently received OFDM symbol according to the preset serial numbers of the partial subcarriers.
10. The apparatus of claim 9, wherein the second unit determines the average value of the channel responses of the currently received OFDM symbol and OFDM symbols adjacent to the currently received OFDM symbol by using the following formula:
wherein the content of the first and second substances,
is the average value of the channel responses on the l +1 th sub-carrier of the currently received OFDM symbol and the OFDM symbol adjacent to the OFDM symbol,
is the conjugate of the frequency domain data of the pilot symbols of the predetermined pilot sequence on the l +1 th subcarrier, Y1,lFrequency domain data of pilot symbols of the currently received OFDM symbols on the (l + 1) th subcarrier, Y0,lAnd M is the frequency domain data of pilot symbols of OFDM symbols adjacent to the currently received OFDM symbol on the (l + 1) th subcarrier, and is the serial number set of the partial subcarriers.
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