CN114244674B - Frequency offset estimation method and device for ultra-wideband baseband receiver - Google Patents

Frequency offset estimation method and device for ultra-wideband baseband receiver Download PDF

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CN114244674B
CN114244674B CN202111603711.4A CN202111603711A CN114244674B CN 114244674 B CN114244674 B CN 114244674B CN 202111603711 A CN202111603711 A CN 202111603711A CN 114244674 B CN114244674 B CN 114244674B
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frequency offset
matched filter
preamble symbol
value
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CN114244674A (en
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李宇
蒋炫佑
景振海
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Changsha Chixin Semiconductor Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2692—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with preamble design, i.e. with negotiation of the synchronisation sequence with transmitter or sequence linked to the algorithm used at the receiver
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention provides a frequency offset estimation method and a frequency offset estimation device of an ultra-wideband baseband receiver, wherein the method comprises the step of expanding the order K of a local leading symbol matched filter by using a zero coefficient tapIs 2 N One tap, the number of adders extending to 2 N‑1 A plurality of; using the output result of the Nth-level local leading symbol matched filter to execute symbol synchronization detection and determining leading symbol synchronization time; performing delayed autocorrelation processing on the output result of the local preamble symbol matched filter according to the time sequence, accumulating the result through an adder, and calculating a fuzzy frequency offset estimation value output from each stage of the local preamble symbol matched filter according to the delay time; obtaining a true value of frequency offset estimation obtained from the Nth-level local preamble symbol matched filter; and the actual value of the frequency offset estimation obtained from the Nth-level local preamble symbol matching filter is recovered by using NCO or AFC. The method and the device for estimating the frequency offset of the ultra-wideband baseband receiver provided by the invention can obtain a high-precision carrier frequency offset estimation result through single frequency offset estimation.

Description

Frequency offset estimation method and device for ultra-wideband baseband receiver
Technical Field
The embodiment of the invention relates to the technical field of ultra wide band, in particular to a frequency offset estimation method and device of an ultra wide band baseband receiver.
Background
An Ultra Wide Band (UWB) is used as a Wideband wireless communication technology, and has the characteristics of high transmission rate, high security, strong multipath fading resistance and the like. However, due to the large bandwidth, the center frequency of the allowed operating frequency band can be up to 10GHz, which requires the baseband system to be able to estimate and recover the large carrier frequency offset.
In response to the situation of large carrier frequency offset, one method usually adopted is to adopt two steps of coarse frequency offset estimation and recovery and fine frequency offset estimation and recovery, but the two-stage processing will result in the consumption of a large number of pilot symbols, which leads to the shortage of pilot resources for subsequent processing. Another method usually adopted is to obtain large frequency offset estimation by using single frequency offset estimation, but the problem that a large amount of storage resources are consumed due to the huge number of sampling points is brought, and because the power of ultra-wideband receiving signals is usually very low, the method of directly obtaining phase difference by using a sampling point cross-correlation mode cannot well eliminate the influence of noise.
It is therefore desirable to provide a frequency offset estimation method that can solve the above problems.
Disclosure of Invention
The invention provides a frequency offset estimation method of an ultra-wideband baseband receiver, which obtains a carrier frequency offset estimation result with high precision and large range by single frequency offset estimation.
The embodiment of the invention provides a frequency offset estimation method of an ultra-wideband baseband receiver, which comprises the following steps:
expanding order K of local pilot symbol matched filter to 2 by using zero coefficient tap N One tap, the number of adders extending to 2 N-1 A plurality of;
using the output result of the Nth-level local leading symbol matched filter to execute symbol synchronization detection and determining leading symbol synchronization time;
after the output results of the local preamble symbol matched filter are subjected to delay autocorrelation processing according to the time sequence, accumulating the results through the adder, and calculating a fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the delay time;
according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, after the non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage is eliminated step by step, the true value of the frequency offset estimation obtained from the Nth-stage local preamble symbol matched filter is obtained;
and the actual value of the frequency offset estimation obtained from the Nth-level local preamble symbol matching filter uses a Numerically Controlled Oscillator (NCO) or an Automatic Frequency Control (AFC) to realize frequency offset recovery.
Preferably, the symbol synchronization detection is performed by using an output result of the nth level local preamble symbol matching filter, and the preamble symbol synchronization time is determined by specifically using the following formula:
Figure GDA0004083526000000021
wherein c (i) represents 2 N The coefficients of an order-local pilot symbol matched filter, τ denotes the time instant, s (τ -i + 1) denotes the sampled complex signal at the time instant τ -i +1, ω (τ) denotes the saidAnd (3) using an output result of the Nth-stage local pilot symbol matched filter, wherein i is an integer and the value range of i is [1,2 ] N ]；
After performing delayed autocorrelation on ω (τ) and accumulating the noise removed, maximum value search is performed on the absolute value of the result to obtain preamble symbol synchronization time t 0 。
Preferably, after the symbol synchronization detection is performed by using the output result of the nth stage local preamble symbol matching filter and the preamble synchronization time is determined, the method further includes the following steps:
dividing the local leading symbol matched filter of each level into a multi-level filtering output result, and obtaining N-level filtering output results for the local leading symbol matched filter of each level, wherein the nth level has 2 N-n A local pilot symbol matched sub-filter, wherein n is an integer and the value range of n is [1,N-1 ]]。
Preferably, 2 for the nth stage N-n Performing correlation processing and accumulation processing on output results of the local preamble symbol matching sub-filters, wherein the output result of the local preamble symbol matching sub-filter of the j-th stage of the ith local preamble symbol matching filter is calculated using the following formula:
Figure GDA0004083526000000031
wherein, a q,j,k Represents the output result of the kth local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter,
Figure GDA0004083526000000032
the conjugate of the output result of the (k + 1) th local leading symbol matched filter of the jth stage of the qth local leading symbol matched filter is represented, wherein q is an integer and has a value range of [1,Q ]]Q is an integer, j is an integer, and j has a value range of [1,N]K is an integer, and the value range of k is [1, (N-N + 1)/2]。
Preferably, after the non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage is eliminated step by step according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, the true value of the frequency offset estimation obtained from the N-th-stage local preamble symbol matched filter is obtained, which specifically includes the following steps:
calculating phase theta of Corr (1) by CORDIC coordinate rotation digital calculation method 1 Using the formula θ 1 ＝f 1 ·t 1 Calculating the frequency deviation estimated value of the first-stage local leading symbol matched filter
Figure GDA0004083526000000037
Wherein t is 1 Represents a time of day;
calculating phase theta of complex Corr (2) by CORDIC coordinate rotation digital calculation method 2 Combining with 2 pi ambiguity to obtain multiple phases [ theta ] 2,1 ,θ 2,2 ,θ 2,3 ,…θ 2,M ]Further, a plurality of corresponding frequency deviation estimated values are obtained
Figure GDA0004083526000000033
The 2 pi ambiguity refers to that the estimated frequency offset result contains a plurality of ambiguity values due to the overlarge correlation time interval of the delayed autocorrelation, and the frequency offset estimation value output by the second stage is determined by using the following formula:
Figure GDA0004083526000000034
Figure GDA0004083526000000035
the CORDIC coordinate rotation digital calculation method is repeatedly used for 3 rd to Nth stages in sequence, so that a high-precision frequency offset estimation result is obtained
Figure GDA0004083526000000036
Wherein M is the number of fuzzy phase values calculated based on the maximum value in the plurality of corresponding frequency offset estimation values and the 2 pi fuzzy;
Figure GDA0004083526000000041
m when the formula reaches the minimum value; argmin means that the numerical value in the parentheses is minimized, and the parameter value at the moment is output, | · | represents the calculation absolute value, wherein m is an integer, and the numeric range of m is [1,M ]]。
The embodiment of the invention also discloses a frequency offset estimation device of the ultra-wideband baseband receiver, which comprises the following components:
a spreading module for spreading the order K of the local pilot symbol matched filter to 2 with a zero coefficient tap N One tap, the number of adders is extended to 2 N-1 A plurality of;
a leading symbol synchronization time determining module, configured to perform symbol synchronization detection using an output result of the nth-stage local leading symbol matching filter, and determine a leading symbol synchronization time;
the fuzzy frequency offset estimation value calculation module is used for performing delay autocorrelation processing on the output result of the local preamble symbol matched filter according to the time sequence, accumulating the result through the adder and calculating the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the delay time;
a frequency offset estimation true value obtaining module, configured to gradually eliminate a non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, and obtain a true value of the frequency offset estimation obtained from the nth-stage local preamble symbol matched filter;
and the frequency offset recovery module is used for realizing frequency offset recovery by using a Numerically Controlled Oscillator (NCO) or an Automatic Frequency Control (AFC) on the actual value of the frequency offset estimation obtained from the Nth-level local preamble symbol matching filter.
Preferably, the symbol synchronization detection is performed by using an output result of the nth stage local preamble symbol matching filter, and the preamble symbol synchronization time is determined by specifically using the following formula:
Figure GDA0004083526000000042
wherein c (i) represents 2 N The coefficient of the order local leading symbol matched filter, tau represents the time, s (tau-i + 1) represents the sampling complex signal of the time of tau-i +1, omega (tau) represents the output result of the N-level local leading symbol matched filter, wherein, i is an integer, and the value range of i is [1,2 ] N ]；
After performing delayed autocorrelation on ω (τ) and accumulating the noise removed, maximum value search is performed on the absolute value of the result to obtain preamble symbol synchronization time t 0 。
Preferably, the method for detecting symbol synchronization by using the output result of the nth stage local preamble symbol matched filter further includes the following steps after determining the preamble symbol synchronization time:
dividing the local leading symbol matched filter of each level into a multi-level filtering output result, and obtaining N-level filtering output results for the local leading symbol matched filter of each level, wherein the nth level has 2 N-n A local pilot symbol matched sub-filter, wherein n is an integer and the value range of n is [1,N-1 ]]。
Preferably, 2 for the nth stage N-n Performing correlation processing and accumulation processing on output results of the local preamble symbol matching sub-filters, wherein the output result of the local preamble symbol matching sub-filter of the j-th stage of the ith local preamble symbol matching filter is calculated using the following formula:
Figure GDA0004083526000000051
wherein, a q,j,k Represents the output result of the kth local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter,
Figure GDA0004083526000000052
the conjugate of the output result of the (k + 1) th local leading symbol matched filter of the jth stage of the qth local leading symbol matched filter is represented, wherein q is an integer and has a value range of [1,Q ]]Q is an integer, j is an integer, and j has a value range of [1,N]K is an integer, and the value range of k is [1, (N-N + 1)/2]。
Preferably, after the non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage is eliminated step by step according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, the true value of the frequency offset estimation obtained from the N-th-stage local preamble symbol matched filter is obtained, which specifically includes the following steps:
calculating phase theta of Corr (1) by CORDIC coordinate rotation digital calculation method 1 Using the formula θ 1 ＝f 1 ·t 1 Calculating the frequency deviation estimated value of the first-stage local leading symbol matched filter
Figure GDA0004083526000000053
Wherein t is 1 Represents a time of day;
calculating phase theta of complex Corr (2) by CORDIC coordinate rotation digital calculation method 2 Combining with 2 pi ambiguity to obtain multiple phases [ theta ] 2,1 ,θ 2,2 ,θ 2,3 ,…θ 2,M ]Further, a plurality of corresponding frequency deviation estimated values are obtained
Figure GDA0004083526000000054
The 2 pi ambiguity refers to that the estimated frequency offset result contains a plurality of ambiguity values due to the overlarge correlation time interval of the delayed autocorrelation, and the frequency offset estimation value output by the second stage is determined by using the following formula:
Figure GDA0004083526000000061
Figure GDA0004083526000000062
the CORDIC coordinate rotation digital calculation method is repeatedly used for 3 rd to Nth stages in sequence, so that a high-precision frequency offset estimation result is obtained
Figure GDA0004083526000000063
Wherein M is the number of fuzzy phase values calculated based on the maximum value in the plurality of corresponding frequency offset estimation values and the 2 pi fuzzy;
Figure GDA0004083526000000064
m when the formula reaches the minimum value; argmin means that the numerical value in the parentheses is minimized, and the parameter value at the moment is output, | · | represents the calculation absolute value, wherein m is an integer, and the numeric range of m is [1,M ]]。
Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:
the frequency offset estimation method and the frequency offset estimation device of the ultra-wideband baseband receiver of the embodiment of the invention expand the order K of the local leading symbol matched filter into 2N taps by using zero coefficient taps and expand the number of adders into 2N-1, execute symbol synchronization detection by using the output result of the Nth-level local leading symbol matched filter, determine the leading symbol synchronization moment, obtain the true value of frequency offset estimation obtained from the Nth-level local leading symbol matched filter according to the frequency offset estimation value of the first-level local leading symbol matched filter, and can realize single frequency offset estimation to obtain a carrier frequency offset estimation result with high precision and large range;
furthermore, by performing correlation processing and accumulation processing on the output result of the local pilot symbol matching sub-filter, a real-time signal processing mode is used instead of a mode of storing before processing, so that a large amount of storage resources are not consumed to store the output result, and a large amount of storage resources can be saved.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below of the drawings required for describing the embodiments or the prior art, and it is apparent that the drawings in the following description are some embodiments of the present invention, but not all embodiments. For a person skilled in the art, other figures can also be obtained from these figures without inventive exercise.
Fig. 1 is a flowchart of a method for estimating a frequency offset of an ultra wideband baseband receiver according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a local preamble symbol matching filter used in a frequency offset estimation method of an ultra-wideband baseband receiver according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of preamble symbols used in a method for estimating frequency offset of an ultra-wideband baseband receiver according to an embodiment of the present invention;
fig. 4 is a block diagram of an apparatus for estimating frequency offset of an ultra-wideband baseband receiver according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
Based on the problems in the prior art, the embodiment of the invention provides a frequency offset estimation method and a frequency offset estimation device for an ultra-wideband baseband receiver, which are used for obtaining a carrier frequency offset estimation result with high precision and large range through single frequency offset estimation.
Fig. 1 is a flowchart of a method for estimating a frequency offset of an ultra wideband baseband receiver according to an embodiment of the present invention. Referring now to fig. 1, a method for estimating a frequency offset of an ultra wideband baseband receiver, comprising the steps of:
s101: expanding order K of local pilot symbol matched filter to 2 by using zero coefficient tap N One tap, the number of adders is extended to 2 N-1 A plurality of;
s102: using the output result of the Nth-level local preamble symbol matching filter to execute symbol synchronization detection and determining the preamble symbol synchronization moment;
s103: after the output results of the local preamble symbol matched filter are subjected to delay autocorrelation processing according to the time sequence, accumulating the results through the adder, and calculating a fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the delay time;
s104: according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, after the non-true value of the fuzzy frequency offset estimation value output from each stage of local preamble symbol matched filter is eliminated step by step, the true value of the frequency offset estimation value obtained from the Nth-stage local preamble symbol matched filter is obtained;
s105: and recovering the frequency offset by using a Numerically Controlled Oscillator (NCO) or an Automatic Frequency Control (AFC) for the true value of the frequency offset estimation obtained from the Nth-level local preamble symbol matching filter.
In a specific implementation, the taps (Tap) in step S101 are coefficients or delay pairs of the local preamble symbol matching filter, and the number of taps means the storage space required for implementing the local preamble symbol matching filter, the number of taps required to be calculated, and the amount that can be filtered by the local preamble symbol matching filter.
In a specific implementation, the non-true value in step S104 refers to only one true frequency offset value in a group of fuzzy values, and the other fuzzy values are referred to as non-true values.
In a specific implementation, the NCO (Numerically Controlled Oscillator) in step S105 is generally called a Numerical Controlled Oscillator (NCO), and the AFC (Automatic Frequency Control) is generally called an Automatic Frequency Control (Automatic Frequency Control).
FIG. 2 isAn exemplary structure of a local preamble symbol matched filter used in a method for estimating a frequency offset of an ultra-wideband baseband receiver according to an embodiment of the present invention is shown. Referring now to fig. 2, a local preamble symbol matched filter with a tap number K is extended to 2 with a zero coefficient tap N And a tap. And defining the sampling complex signal of the ADC at the time t as s (t), and the number of sampling points in one preamble symbol as K.
In a specific implementation, the determining of the preamble symbol synchronization time in step S102 refers to determining a start time of the preamble symbol. 2 N The coefficients of the order local pilot symbol matched filter are c (1), c (2), … c (2) in sequence N ) Performing symbol synchronization detection by using an output result of the nth-stage local preamble symbol matched filter to determine a preamble symbol synchronization time, specifically calculating by using the following formula:
Figure GDA0004083526000000081
after the delay autocorrelation is carried out on the output result omega (tau) of the matched filtering and the noise is eliminated by accumulation, the maximum value retrieval is carried out on the absolute value of the result so as to obtain the synchronous time t of the preamble symbol 0 Then, then
[s(t 0 +L·K),s(t 0 +L·K+1),…s(t 0 +L·K+K-1)]
I.e. the lth complete set of preamble symbol sample data. Synchronizing time t with preamble symbol 0 A complete set of sample points for a preamble symbol can be determined for a time reference, where i is an integer and i ranges from [1,2N ]]。
In a specific implementation, the performing symbol synchronization detection using the output result of the nth stage local preamble symbol matched filter further includes, after determining a preamble synchronization time, the following steps: dividing the local leading symbol matched filter of each level into a multi-level filtering output result, and obtaining N levels of filtering output results for the local leading symbol matched filter of each level, wherein the nth level is 2 in total N-n A local pilot symbol matched sub-filter, wherein n is an integer and has a value range of [1,N-1]。
for example, if the first stage local pilot symbol matched filter uses two adjacent sampling points as the filtering output result, it is equivalent to divide the original local pilot symbol matched filter with one pilot symbol length into 2 N-1 The local pilot symbol matched sub-filters can select more taps as the output of the first-stage local pilot symbol matched filter in the practical ultra-wideband baseband system.
Fig. 3 is a schematic structural diagram of a preamble symbol used in a frequency offset estimation method of an ultra-wideband baseband receiver according to an embodiment of the present invention. Referring now to fig. 3, for each complete preamble symbol, the output of an N-stage local preamble symbol matched filter can be obtained, where the nth stage has a total of 2 N-n The output result of the kth local leading symbol matched filter of the j stage of the qth leading symbol is a q,j,k Which is a complex number.
In specific implementation, 2 of the nth stage N-n Performing correlation processing and accumulation processing on output results of the local preamble symbol matching sub-filters, wherein the output result of the local preamble symbol matching sub-filter of the j-th stage of the q-th local preamble symbol matching filter is calculated using the following formula:
Figure GDA0004083526000000091
wherein, a q,j,k Represents the output result of the kth local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter,
Figure GDA0004083526000000092
the conjugate of the output result of the (k + 1) th local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter is represented, wherein q is an integer and the value range of q is [1,Q [ ]]Q is an integer, j is an integer, and j has a value range of [1,N]K is an integer, and the value range of k is [1, (N-N + 1)/2]。
The shorter the time interval of the two pieces of relevant data is, the larger the range of the frequency offset which can be estimated is, and the worse the frequency offset estimation accuracy is, and the longer the time interval of the relevant data is, although the frequency offset estimation accuracy can be significantly improved, the range of the frequency offset which can be estimated is reduced, and when the large carrier frequency offset is directly estimated, a plurality of fuzzy estimation results can be caused to occur, wherein the number of the fuzzy estimation results is related to the maximum carrier frequency offset which is expected to possibly occur. Therefore, in the specific implementation, the upper limit of the frequency offset estimation obtained by the frequency offset estimation system is the unambiguous frequency offset value range calculated by using the first-stage matched filtering result.
In a specific implementation, in step S104, after removing the non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage step by step according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, the true value of the frequency offset estimation obtained from the nth-stage local preamble symbol matched filter is obtained, which specifically includes the following steps:
calculating phase theta of Corr (1) by CORDIC coordinate rotation digital calculation method 1 Using the formula θ 1 ＝f 1 ·t 1 Calculating the frequency deviation estimated value of the first-stage local leading symbol matched filter
Figure GDA0004083526000000101
Wherein t is 1 Represents a time of day;
calculating phase theta of complex Corr (2) by CORDIC coordinate rotation digital calculation method 2 Combining with 2 pi ambiguity to obtain multiple phases [ theta ] 2,1 ,θ 2,2 ,θ 2,3 ,…θ 2,M ]Further, a plurality of corresponding frequency deviation estimated values are obtained
Figure GDA0004083526000000102
Determining a frequency offset estimate for the second stage output using the following equation:
Figure GDA0004083526000000103
Figure GDA0004083526000000104
the CORDIC algorithm is repeatedly used for the 3 rd stage to the Nth stage in sequence, so that a high-precision frequency offset estimation result is obtained
Figure GDA0004083526000000105
Wherein M is the number of fuzzy phase values calculated based on the maximum value in the plurality of corresponding frequency offset estimation values and the 2 pi fuzzy;
Figure GDA0004083526000000106
m when the formula reaches the minimum value; argmin means that the numerical value in the parentheses is minimized, and the parameter value at the moment is output, | · | represents the calculation absolute value, wherein m is an integer, and the numeric range of m is [1,M ]]。
In specific implementation, the 2 pi ambiguity refers to that the estimated frequency offset result contains a plurality of ambiguity values due to too large correlation time interval of delayed autocorrelation, and the phase difference between the ambiguity values is an integer multiple of 2 pi, which is called as 2 pi ambiguity.
Fig. 4 is a block diagram of an apparatus for estimating frequency offset of an ultra-wideband baseband receiver according to an embodiment of the present invention. Referring now to fig. 4, an apparatus for estimating frequency offset of an ultra-wideband baseband receiver according to another embodiment of the present invention includes:
a spreading module 21 for spreading the order K of the local pilot symbol matched filter to 2 with a zero coefficient tap N One tap, the number of adders extending to 2 N-1 A plurality of;
a preamble symbol synchronization timing determining module 22, configured to perform symbol synchronization detection using an output result of the nth-stage local preamble symbol matching filter, and determine a preamble symbol synchronization timing;
a fuzzy frequency offset estimation value calculation module 23, configured to perform delay autocorrelation processing on the output result of the local preamble symbol matched filter according to the time sequence, accumulate the result through the adder, and calculate a fuzzy frequency offset estimation value output from each stage of the local preamble symbol matched filter according to the delay time;
a frequency offset estimation true value obtaining module 24, configured to gradually eliminate a non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, and obtain a true value of the frequency offset estimation obtained from the nth-stage local preamble symbol matched filter;
a frequency offset recovery module 25, configured to implement frequency offset recovery using NCO or AFC on the true value of the frequency offset estimation obtained from the nth stage local preamble symbol matching filter.
In a specific implementation, the symbol synchronization detection is performed by using an output result of the nth-stage local preamble symbol matching filter, and a preamble symbol synchronization time is determined, which is specifically calculated by using the following formula:
Figure GDA0004083526000000111
wherein c (i) represents 2 N The coefficient of the order local leading symbol matched filter, tau represents time, s (tau-i + 1) represents a sampling complex signal at the time of tau-i +1, and omega (tau) represents an output result of the N-th stage local leading symbol matched filter, wherein i is an integer, and the value range of i is [1,2 [ ] N ]；
After performing delayed autocorrelation on ω (τ) and accumulating the noise removed, maximum value search is performed on the absolute value of the result to obtain preamble symbol synchronization time t 0 。
In a specific implementation, after the symbol synchronization detection is performed by using an output result of the nth stage local preamble symbol matching filter and the preamble symbol synchronization time is determined, the method further includes the following steps:
dividing the local leading symbol matched filter of each level into a multi-level filtering output result, and obtaining N-level filtering output results for the local leading symbol matched filter of each levelWherein the nth stage has a total of 2 N-n A local pilot symbol matched sub-filter, wherein n is an integer and the value range of n is [1,N-1 ]]。
In specific implementation, 2 of the nth stage N-n Performing correlation processing and accumulation processing on output results of the local preamble symbol matching sub-filters, wherein the output result of the local preamble symbol matching sub-filter of the j-th stage of the q-th local preamble symbol matching filter is calculated using the following formula:
Figure GDA0004083526000000121
wherein, a q,j,k Represents the output result of the kth local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter,
Figure GDA0004083526000000122
the conjugate of the output result of the (k + 1) th local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter is represented, wherein q is an integer and the value range of q is [1,Q [ ]]Q is an integer, j is an integer, and j has a value range of [1,N]K is an integer, and the value range of k is [1, (N-N + 1)/2]。
In a specific implementation, after the non-true value of the fuzzy frequency offset estimation value output from each level of the local preamble symbol matching filter is eliminated step by step according to the frequency offset estimation value of the first level of the local preamble symbol matching filter, the true value of the frequency offset estimation obtained from the nth level of the local preamble symbol matching filter is obtained, which specifically includes the following steps:
calculating phase theta of Corr (1) using CORDIC algorithm 1 Using the formula θ 1 ＝f 1 ·t 1 Calculating the frequency deviation estimated value of the first-stage local leading symbol matched filter
Figure GDA0004083526000000126
Wherein t is 1 Represents a time of day;
calculating complex number C using CORDIC algorithmorr (2) phase θ 2 Combining with 2 pi ambiguity to obtain multiple phases [ theta ] 2,1 ,θ 2,2 ,θ 2,3 ,…θ 2,M ]Further, a plurality of corresponding frequency deviation estimated values are obtained
Figure GDA0004083526000000123
Determining a frequency offset estimate for the second stage output using the following equation:
Figure GDA0004083526000000124
Figure GDA0004083526000000125
the CORDIC algorithm is repeatedly used for the 3 rd stage to the Nth stage in sequence, so that a high-precision frequency offset estimation result is obtained
Figure GDA0004083526000000131
Wherein M is the number of fuzzy phase values calculated based on the maximum value in the plurality of corresponding frequency offset estimation values and the 2 pi fuzzy;
Figure GDA0004083526000000132
m when the formula reaches the minimum value; argmin means that the numerical value in the parentheses is minimized, and the parameter value at the moment is output, | · | represents the calculation absolute value, wherein m is an integer, and the numeric range of m is [1,M ]]。
In summary, in the frequency offset estimation method and apparatus for an ultra wideband baseband receiver according to the embodiments of the present invention, the order K of the local preamble symbol matched filter is extended to 2N taps by using zero-coefficient taps and the number of adders is extended to 2N-1, symbol synchronization detection is performed by using the output result of the nth-stage local preamble symbol matched filter, a preamble symbol synchronization time is determined, the true value of the frequency offset estimation obtained from the nth-stage local preamble symbol matched filter is obtained according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, and a single frequency offset estimation can be implemented to obtain a carrier frequency offset estimation result with high precision and large range;
furthermore, by performing correlation processing and accumulation processing on the output result of the local pilot symbol matching sub-filter, a real-time signal processing mode is used instead of a mode of storing before processing, so that a large amount of storage resources are not consumed to store the output result, and a large amount of storage resources can be saved.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (6)

1. A frequency deviation estimation method of an ultra-wideband baseband receiver is characterized by comprising the following steps:
expanding order K of local pilot symbol matched filter to 2 by using zero coefficient tap N One tap, the number of adders extending to 2 N-1 A plurality of;
and executing symbol synchronization detection by using an output result of the Nth-level local leading symbol matched filter, determining a leading symbol synchronization moment, and specifically calculating by using the following formula:
Figure FDA0004083525990000011
wherein c (i) represents 2 N The coefficient of the order local leading symbol matched filter, tau represents time, s (tau-i + 1) represents a sampling complex signal at the time of tau-i +1, and omega (tau) represents an output result of the N-th level local leading symbol matched filter at the time of tau, wherein i is an integer, and the value range of i is [1,2 N ]；
After performing delay autocorrelation on ω (τ) and accumulating the cancellation noise, maximum value search is performed on the absolute value of the result to obtain the preamble symbol synchronization time t 0 ；
Dividing the local leading symbol matched filter of each level into a multi-level filtering output result, and obtaining N levels of filtering output results for the local leading symbol matched filter of each level, wherein the nth level is 2 in total N-n A local pilot symbol matched sub-filter, wherein n is an integer and the value range of n is [1,N-1 ]]；
To 2 of the nth stage N-n The output result of the local preamble symbol matching sub-filter performs correlation processing and accumulation processing, wherein the output result of the j-th stage local preamble symbol matching sub-filter of the q-th local preamble symbol matching filter is calculated using the following formula:
Figure FDA0004083525990000012
wherein, a q,j,k Represents the output result of the kth local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter,
Figure FDA0004083525990000013
the conjugate of the output result of the (k + 1) th local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter is represented, wherein q is an integer and the value range of q is [1,Q [ ]]Q is an integer, j is an integer, and j has a value range of [1,N]K is an integer, and the value range of k is [1, (N-N + 1)/2]；
After the output results of the local preamble symbol matched filter are subjected to delay autocorrelation processing according to the time sequence, accumulating the results through the adder, and calculating a fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the delay time;
according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, after the non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage is eliminated step by step, the true value of the frequency offset estimation obtained from the Nth-stage local preamble symbol matched filter is obtained;
calculating phase theta of Corr (1) by CORDIC coordinate rotation digital calculation method 1 Using the formula θ 1 ＝f 1 ·t 1 Calculating the frequency deviation estimated value of the first-stage local leading symbol matched filter
Figure FDA0004083525990000021
Wherein t is 1 Represents a time of day;
calculating phase theta of complex Corr (2) by CORDIC coordinate rotation digital calculation method 2 Combining with 2 pi ambiguity to obtain multiple phases [ theta ] 2,1 ,θ 2,2 ,θ 2,3 ,…θ 2,M ]Further, a plurality of corresponding frequency deviation estimated values are obtained
Figure FDA0004083525990000022
The 2 pi ambiguity refers to that the estimated frequency offset result contains a plurality of ambiguity values due to the overlarge correlation time interval of the delayed autocorrelation, and the frequency offset estimation value output by the second stage is determined by using the following formula:
Figure FDA0004083525990000023
Figure FDA0004083525990000024
the CORDIC coordinate rotation digital calculation method is repeatedly used for 3 rd to Nth stages in sequence, so that a high-precision frequency offset estimation result is obtained
Figure FDA0004083525990000025
Wherein M is the number of fuzzy phase values calculated based on the maximum value in the plurality of corresponding frequency offset estimation values and the 2 pi fuzzy;
Figure FDA0004083525990000026
m when the formula reaches the minimum value; argmin means that the numerical value in the parentheses is minimized, and the parameter value at the moment is output, | · | represents the calculation absolute value, wherein m is an integer, and the numeric range of m is [1,M ]]；
And recovering the frequency offset by using a Numerically Controlled Oscillator (NCO) or an Automatic Frequency Control (AFC) for the true value of the frequency offset estimation obtained from the Nth-level local preamble symbol matching filter.
2. The method of claim 1, wherein the taps are coefficients of a local preamble symbol matched filter.
3. The method of claim 1, wherein the time t is synchronized with a preamble symbol 0 A complete set of sample points for a complete preamble symbol is determined for the time reference.
4. An apparatus for estimating frequency offset of an ultra-wideband baseband receiver, comprising:
an expansion module for expanding the order K of the local pilot symbol matched filter to 2 with a zero coefficient tap N One tap, the number of adders extending to 2 N-1 A plurality of;
a preamble symbol synchronization time determining module, configured to perform symbol synchronization detection using an output result of the nth-stage local preamble symbol matching filter, determine a preamble symbol synchronization time, and specifically calculate using the following formula:
Figure FDA0004083525990000031
wherein c (i) represents 2 N The order of the locally leading symbols matches the coefficients of the filter,tau represents time, s (tau-i + 1) represents sampling complex signal at the time of tau-i +1, omega (tau) represents output result of the N-th stage local preamble symbol matched filter at the time of tau, wherein i is an integer, and the value range of i is [1,2 ] N ]；
After performing delayed autocorrelation on ω (τ) and accumulating the noise removed, maximum value search is performed on the absolute value of the result to obtain preamble symbol synchronization time t 0 ；
Dividing the local leading symbol matched filter of each level into a multi-level filtering output result, and obtaining N-level filtering output results for the local leading symbol matched filter of each level, wherein the nth level has 2 N-n A local pilot symbol matched sub-filter, wherein n is an integer and the value range of n is [1,N-1 ]]；
To 2 of the nth stage N-n Performing correlation processing and accumulation processing on output results of the local preamble symbol matching sub-filters, wherein the output result of the local preamble symbol matching sub-filter of the j-th stage of the ith local preamble symbol matching filter is calculated using the following formula:
Figure FDA0004083525990000032
wherein, a q,j,k Represents the output result of the kth local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter,
Figure FDA0004083525990000041
the conjugate of the output result of the (k + 1) th local preamble symbol matched filter of the jth stage of the qth local preamble symbol matched filter is represented, wherein q is an integer and the value range of q is [1,Q [ ]]Q is an integer, j is an integer, and j has a value range of [1,N]K is an integer, and the value range of k is [1, (N-N + 1)/2]；
The fuzzy frequency offset estimation value calculation module is used for performing delay autocorrelation processing on the output result of the local preamble symbol matched filter according to the time sequence, accumulating the result through the adder and calculating the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the delay time;
a frequency offset estimation true value obtaining module, configured to gradually eliminate a non-true value of the fuzzy frequency offset estimation value output from the local preamble symbol matched filter of each stage according to the frequency offset estimation value of the first-stage local preamble symbol matched filter, and obtain a true value of the frequency offset estimation obtained from the nth-stage local preamble symbol matched filter;
calculating phase theta of Corr (1) by CORDIC coordinate rotation digital calculation method 1 Using the formula θ 1 ＝f 1 ·t 1 Calculating the frequency deviation estimated value of the first-stage local leading symbol matched filter
Figure FDA0004083525990000042
Wherein t is 1 Represents a time of day;
calculating phase theta of complex Corr (2) by CORDIC coordinate rotation digital calculation method 2 Combining with 2 pi ambiguity to obtain multiple phases [ theta ] 2,1 ,θ 2,2 ,θ 2,3 ,…θ 2,M ]Further, a plurality of corresponding frequency deviation estimated values are obtained
Figure FDA0004083525990000043
The 2 pi ambiguity refers to that the estimated frequency offset result contains a plurality of ambiguity values due to the overlarge correlation time interval of the delayed autocorrelation, and the frequency offset estimation value output by the second stage is determined by using the following formula:
Figure FDA0004083525990000044
Figure FDA0004083525990000045
repeating the CORDIC coordinate rotation digital calculation method for the 3 rd to the Nth stages in sequence to obtainObtaining high-precision frequency offset estimation result
Figure FDA0004083525990000046
Wherein M is the number of fuzzy phase values calculated based on the maximum value in the plurality of corresponding frequency offset estimation values and the 2 pi fuzzy;
Figure FDA0004083525990000047
m when the formula reaches the minimum value; argmin means that the numerical value in the parentheses is minimized, and the parameter value at the moment is output, | · | represents the calculation absolute value, wherein m is an integer, and the numeric range of m is [1,M ]]；
And the frequency offset recovery module is used for realizing frequency offset recovery on the actual value of the frequency offset estimation obtained from the Nth-level local preamble symbol matching filter by using a Numerically Controlled Oscillator (NCO) or an Automatic Frequency Control (AFC).
5. The apparatus of claim 4, wherein the taps are coefficients of a local preamble symbol matched filter.
6. The apparatus of claim 4, wherein the time t is synchronized with the preamble symbol by the frequency offset estimation apparatus of the UWB baseband receiver 0 A complete set of sample points for a complete preamble symbol is determined for the time reference.
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