CN114666190A - Channel estimation method based on improved time domain interpolation - Google Patents

Channel estimation method based on improved time domain interpolation Download PDF

Info

Publication number
CN114666190A
CN114666190A CN202210276327.6A CN202210276327A CN114666190A CN 114666190 A CN114666190 A CN 114666190A CN 202210276327 A CN202210276327 A CN 202210276327A CN 114666190 A CN114666190 A CN 114666190A
Authority
CN
China
Prior art keywords
pilot
channel estimation
interpolation
channel
time domain
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202210276327.6A
Other languages
Chinese (zh)
Other versions
CN114666190B (en
Inventor
张烨楠
许飞云
胡建中
贾民平
黄鹏
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Southeast University
Original Assignee
Southeast University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Southeast University filed Critical Southeast University
Priority to CN202210276327.6A priority Critical patent/CN114666190B/en
Publication of CN114666190A publication Critical patent/CN114666190A/en
Application granted granted Critical
Publication of CN114666190B publication Critical patent/CN114666190B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/024—Channel estimation channel estimation algorithms
    • 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
    • H04L27/2602—Signal structure
    • H04L27/261—Details of reference signals
    • H04L27/2613—Structure of the reference signals
    • H04L27/26134—Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain

Abstract

The invention discloses a channel estimation method based on improved time domain interpolation, which relates to the technical field of wireless communication and solves the technical problem that the time domain interpolation in OFDM channel estimation can not flexibly select pilot intervals; compared with the traditional time domain interpolation method, the pilot frequency interval can be flexibly selected according to the channel characteristics, so that the consumption of the number of the pilot frequencies and the channel estimation to the sub-carriers is reduced, and the method has higher use flexibility; the method has low complexity and is easy to realize.

Description

Channel estimation method based on improved time domain interpolation
Technical Field
The present application relates to the field of wireless communication technologies, and in particular, to a channel estimation method based on improved time domain interpolation.
Background
Orthogonal Frequency Division Multiplexing (OFDM) is a parallel multi-carrier modulation technology, has better anti-multipath interference capability and spectrum utilization efficiency, and has wide application. Channel estimation is one of the key techniques of OFDM, in which a received signal is distorted due to the influence of channel characteristics, and the influence of the channel is estimated at a receiver in order to recover transmitted information.
The pilot-based channel estimation method includes a least square method (LS), a minimum mean square error method (MMSE), and the like. Although the LS channel estimation has larger error, the calculation complexity is low, the prior knowledge of the channel is not needed, and the application is wide; although the MMSE channel estimation improves the algorithm accuracy to a certain extent, it brings about a great calculation overhead. The LS channel estimation method for inserting pilots in the frequency domain first obtains channel estimation values at the pilots, and then obtains channel estimation values of all subcarriers by interpolation, and the interpolation method can be roughly divided into a frequency domain interpolation method, a time domain interpolation method, a transform domain interpolation method, and the like. The time domain interpolation method has better precision, can be realized by a Fast Fourier Transform (FFT) algorithm, and has lower complexity.
The time domain interpolation is used if the pilots are inserted at equal intervals and the number of subcarriers is an integer multiple of the pilot interval. While for the pilot inserted in the frequency domain, the pilot interval is determined by the maximum delay of the Channel Impulse Response (CIR), for the channel with large delay spread, the pilot used for channel estimation consumes a lot of subcarrier resources. A reasonable pilot spacing should minimize the number of subcarriers consumed by the pilot while ensuring channel estimation performance. In order to satisfy the condition that the number of subcarriers is an integral multiple of the pilot interval, the time-domain interpolation may need to select a smaller pilot interval, thereby increasing the overhead of the number of pilots.
Disclosure of Invention
The application provides a channel estimation method based on improved time domain interpolation, and the technical purpose is that the time domain interpolation can flexibly select a pilot frequency interval in OFDM channel estimation.
The technical purpose of the application is realized by the following technical scheme:
a channel estimation method based on improved time domain interpolation comprises the following steps:
step 1, determining subcarrier numberNumber N, number of pilots NPAnd pilot frequency interval m, inserting pilot frequency at equal interval, and inserting the first pilot frequency at the position of the first subcarrier;
step 2, estimating channels of all pilot frequency positions by a least square method to obtain channel estimation values of the pilot frequency positions
Figure BDA0003555877550000011
Then
Figure BDA0003555877550000012
Has a length of NP(ii) a Wherein i represents the number of the pilot;
step 3, carrying out linear interpolation on the subcarriers to obtain linear interpolation results of all the subcarriers
Figure BDA0003555877550000013
Then
Figure BDA0003555877550000014
Is N; wherein k represents the number of subcarriers;
step 4, for
Figure BDA0003555877550000015
Performing fast Fourier inverse transformation of N points to obtain a first channel impulse response estimation result under linear interpolation
Figure BDA0003555877550000016
Then
Figure BDA0003555877550000017
Is N; wherein n represents the sampling order in the time domain;
step 5, for
Figure BDA0003555877550000021
Front N inPCorrecting to obtain the second channel impulse response estimation result
Figure BDA0003555877550000022
Then
Figure BDA0003555877550000023
Has a length of NP；
Step 6, in
Figure BDA0003555877550000024
Tail patch (N-N)P) Is zero to obtain
Figure BDA0003555877550000025
Then
Figure BDA0003555877550000026
Is N;
step 7, for
Figure BDA0003555877550000027
Performing N-point fast Fourier transform to obtain channel estimation values of all subcarriers
Figure BDA0003555877550000028
Further, in step 2, the channel estimation value at the pilot frequency is a result obtained by dividing a signal received after the channel at the pilot frequency is passed by the pilot symbol sent by the transmitter of the corresponding subcarrier.
Further, in step 3, the performing linear interpolation on the subcarriers includes: the interpolation result of the sub-carriers between the first pilot position and the last pilot position is obtained by estimating the channel estimation value at the pilot
Figure BDA0003555877550000029
Linear interpolation is carried out to obtain the interpolation result of the sub-carrier outside the last pilot frequency position through the channel estimation value at the last 2 pilot frequencies;
the channel estimate at the last 2 pilots is
Figure BDA00035558775500000210
And
Figure BDA00035558775500000211
then:
Figure BDA00035558775500000212
by passing
Figure BDA00035558775500000213
And
Figure BDA00035558775500000214
carrying out linear interpolation to obtain an interpolation result of the sub-carriers outside the last pilot frequency position;
the linear interpolation result for all sub-carriers is then expressed as:
Figure BDA00035558775500000215
obtained
Figure BDA00035558775500000216
Has a length of mNPRetention of only mNPAs the first N results in
Figure BDA00035558775500000217
Further, in said step 5, for
Figure BDA00035558775500000218
Front N inPThe correcting comprises the following steps:
Figure BDA00035558775500000219
Figure BDA00035558775500000220
wherein, the first and the second end of the pipe are connected with each other,<3/4·NP>denotes that 3/4 is greater than or equal to·NPIs the smallest integer of (a).
Further, in the step 6, in
Figure BDA00035558775500000221
Tail patch of (N-N)P) Each zero comprises:
Figure BDA00035558775500000222
the beneficial effect of this application lies in: the method and the device have the advantages that linear interpolation is carried out on the subcarrier channel estimation result, approximate time domain interpolation is realized on the basis of the linear interpolation result, high interpolation precision is achieved, and interpolation precision similar to the time domain interpolation is provided; compared with the traditional time domain interpolation method, the pilot frequency interval can be flexibly selected according to the channel characteristics, so that the consumption of the number of the pilot frequencies and the channel estimation to the sub-carriers is reduced, and the method has higher use flexibility; the method has low complexity and is easy to realize.
Drawings
FIG. 1 is a flow chart of a method described herein;
fig. 2 is a simulation graph of Bit Error Rate (BER) at different signal-to-noise ratios (SNRs) according to the present application.
Detailed Description
The technical solution of the present application will be described in detail below with reference to the accompanying drawings.
The application provides a channel estimation method based on improved time domain interpolation, aiming at the problem that the time domain interpolation in OFDM channel estimation can not flexibly select pilot frequency intervals, the application carries out linear interpolation on subcarrier channel estimation results, realizes approximate time domain interpolation on the basis of the linear interpolation results, and can flexibly select the pilot frequency intervals.
Example 1:
a channel estimation method based on improved time domain interpolation is disclosed, and its implementation flow chart is shown in FIG. 1, and its calculation steps are as follows:
the channel impulse response of the channel to be estimated in the present application is:
h[n]＝δ[n]+0.3162δ[n-2]+0.1995δ[n-17]+0.1296δ[n-36]+0.1δ[n-75]+0.1δ[n-137]
the unit time delay is the sampling interval of the channel impulse response.
Step 1, the number of subcarriers is 1024, the pilot interval is 5, the pilots are inserted at equal intervals, the first pilot is placed at the position of the first subcarrier, and the number of the pilots is 205.
Step 2, estimating the channels of all pilot frequency positions by a least square method to obtain the channel estimation value of the pilot frequency positions
Figure BDA0003555877550000031
Is 205, and i is the number of pilots.
Step 3, carrying out linear interpolation on the sub-carriers with the sub-carrier numbers after the last pilot frequency to obtain the linear interpolation results of all the sub-carriers
Figure BDA0003555877550000032
Is 1024, k is the number of the sub-carriers.
Specifically, the linear interpolation is derived in the following specific form:
in order to linearly interpolate the sub-carriers whose sub-carrier number follows the last pilot, let
Figure BDA0003555877550000033
Comprises the following steps:
Figure BDA0003555877550000034
obtaining interpolation results of all subcarriers:
Figure BDA0003555877550000035
obtained
Figure BDA0003555877550000036
Has a length of 1025, only the first 1024 results are retained.
Step 4, for
Figure BDA0003555877550000037
Performing 1024-point IFFT to obtain CIR (channel impulse response) estimation result under linear interpolation
Figure BDA0003555877550000038
n is the sampling order in the time domain.
Step 5, for
Figure BDA0003555877550000039
Front N inPThe correction is performed to obtain more accurate (CIR) estimation result
Figure BDA00035558775500000310
Has a length of 205.
Specifically, for
Figure BDA00035558775500000311
The specific derivation of the treatment is as follows:
Figure BDA00035558775500000312
Figure BDA00035558775500000313
step 6, in
Figure BDA00035558775500000314
819 are complemented to obtain
Figure BDA00035558775500000315
Then
Figure BDA00035558775500000316
Is 1024;
specifically, the specific derivation of zero padding is as follows:
Figure BDA0003555877550000041
step 7, for
Figure BDA0003555877550000042
Performing 1024-point FFT to obtain channel estimation values of all subcarriers
Figure BDA0003555877550000043
Other parameters are unchanged, under the condition that the pilot frequency interval m is 4 and 6, the corresponding pilot frequency numbers are 256 and 171, and the steps 2 to 7 are repeated to obtain corresponding pilot frequency values
Figure BDA0003555877550000044
Fig. 2 shows BER performance results of linear interpolation (pilot interval of 4), time domain interpolation (pilot interval of 4), and the present application (pilot intervals of 4, 5, and 6) under the same parameter configuration. As can be seen from fig. 2, the present application is superior to linear interpolation, and the performance is equivalent to the time domain interpolation performance when the pilot interval is 4, and the performance is slightly reduced when the pilot intervals are 5 and 6, but still has better accuracy.
When the pilot interval is 5, the application reduces the use of 51 pilots compared with time domain interpolation; when the pilot interval is 6, the application reduces the use of 85 pilots compared with time domain interpolation. The pilot frequency interval can be flexibly selected according to the precision requirement and the resource consumption.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (5)

1. A channel estimation method based on improved time domain interpolation is characterized by comprising the following steps:
step 1, determining the number N of subcarriers and the number N of pilot frequenciesPAnd pilot interval m, pilot is inserted at equal intervals, and the first pilot is insertedTo the position of the first subcarrier;
step 2, estimating channels of all pilot frequency positions by a least square method to obtain channel estimation values of the pilot frequency positions
Figure FDA0003555877540000011
Then
Figure FDA0003555877540000012
Has a length of NP(ii) a Wherein i represents the number of the pilot;
step 3, carrying out linear interpolation on the subcarriers to obtain linear interpolation results of all the subcarriers
Figure FDA0003555877540000013
Then
Figure FDA0003555877540000014
Is N; wherein k represents the number of subcarriers;
step 4, for
Figure FDA0003555877540000015
Performing fast Fourier inverse transformation of N points to obtain a first channel impulse response estimation result under linear interpolation
Figure FDA0003555877540000016
Then
Figure FDA0003555877540000017
Is N; wherein n represents the sampling order in the time domain;
step 5, for
Figure FDA0003555877540000018
Front N inPCorrecting to obtain the second channel impulse response estimation result
Figure FDA0003555877540000019
Then
Figure FDA00035558775400000110
Is of length NP；
Step 6, in
Figure FDA00035558775400000111
Tail patch of (N-N)P) Is zero to obtain
Figure FDA00035558775400000112
Then the
Figure FDA00035558775400000113
Is N;
step 7, for
Figure FDA00035558775400000114
Performing N-point fast Fourier transform to obtain channel estimation values of all subcarriers
Figure FDA00035558775400000115
2. The channel estimation method of claim 1, wherein in step 2, the channel estimation value at the pilot frequency is obtained by dividing a signal received at the pilot frequency after passing through the channel by a pilot symbol transmitted by a transmitter of a corresponding subcarrier.
3. The channel estimation method of claim 2, wherein the step 3 of linearly interpolating the subcarriers comprises: the interpolation result of the sub-carriers between the first pilot position and the last pilot position is obtained by estimating the channel estimation value at the pilot
Figure FDA00035558775400000116
Linear interpolation is carried out to obtain the interpolation result of the sub-carriers outside the position of the last pilot frequency, and the interpolation result passes through the positions of the last 2 pilot frequenciesObtaining the channel estimation value;
the channel estimate at the last 2 pilots is
Figure FDA00035558775400000117
And
Figure FDA00035558775400000118
then:
Figure FDA00035558775400000119
by passing
Figure FDA00035558775400000120
And
Figure FDA00035558775400000121
carrying out linear interpolation to obtain an interpolation result of the sub-carriers outside the last pilot frequency position;
the linear interpolation result for all sub-carriers is then expressed as:
Figure FDA00035558775400000122
obtained by
Figure FDA00035558775400000123
Has a length of mNPRetention of only mNPAs the first N results in
Figure FDA00035558775400000124
4. The channel estimation method of claim 3, wherein in step 5, the channel estimation method is applied to
Figure FDA00035558775400000125
Front N inPThe correcting comprises the following steps:
Figure FDA00035558775400000126
Figure FDA00035558775400000127
wherein the content of the first and second substances,<3/4·NP>denotes that 3/4. multidot.N is greater than or equal toPThe smallest integer of (c).
5. The channel estimation method of claim 4, wherein in step 6, in
Figure FDA0003555877540000021
Tail patch (N-N)P) Each zero comprises:
Figure FDA0003555877540000022
CN202210276327.6A 2022-03-21 2022-03-21 Channel estimation method based on improved time domain interpolation Active CN114666190B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210276327.6A CN114666190B (en) 2022-03-21 2022-03-21 Channel estimation method based on improved time domain interpolation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210276327.6A CN114666190B (en) 2022-03-21 2022-03-21 Channel estimation method based on improved time domain interpolation

Publications (2)

Publication Number Publication Date
CN114666190A true CN114666190A (en) 2022-06-24
CN114666190B CN114666190B (en) 2024-01-26

Family

ID=82030508

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210276327.6A Active CN114666190B (en) 2022-03-21 2022-03-21 Channel estimation method based on improved time domain interpolation

Country Status (1)

Country Link
CN (1) CN114666190B (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102263713A (en) * 2011-08-29 2011-11-30 天津大学 Two-dimensional OFDM (orthogonal frequency division multiplexing) channel estimation method based on filtering in transform domain
WO2015196629A1 (en) * 2014-06-27 2015-12-30 中兴通讯股份有限公司 Method and device for estimating frequency offset of carriers
CN107171984A (en) * 2017-05-09 2017-09-15 东南大学 A kind of asynchronous multi-carrier system frequency domain channel estimation method
CN111600816A (en) * 2020-05-12 2020-08-28 国网河北省电力有限公司电力科学研究院 Two-dimensional interpolation channel estimation method for power line carrier communication

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102263713A (en) * 2011-08-29 2011-11-30 天津大学 Two-dimensional OFDM (orthogonal frequency division multiplexing) channel estimation method based on filtering in transform domain
WO2015196629A1 (en) * 2014-06-27 2015-12-30 中兴通讯股份有限公司 Method and device for estimating frequency offset of carriers
CN107171984A (en) * 2017-05-09 2017-09-15 东南大学 A kind of asynchronous multi-carrier system frequency domain channel estimation method
CN111600816A (en) * 2020-05-12 2020-08-28 国网河北省电力有限公司电力科学研究院 Two-dimensional interpolation channel estimation method for power line carrier communication

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
李慧敏;张治中;李琳潇;: "LTE-A系统中基于小区参考信号的信道估计算法", 计算机应用, no. 07 *

Also Published As

Publication number Publication date
CN114666190B (en) 2024-01-26

Similar Documents

Publication Publication Date Title
Yang et al. Windowed DFT based pilot-symbol-aided channel estimation for OFDM systems in multipath fading channels
TWI422193B (en) Channel estimation apparatus and method thereof
KR100896654B1 (en) Apparatus and method for estimating delay spread of multi-path fading channel in ofdm system
CN110868369B (en) Uplink channel estimation method and device based on 5G NR system
CN101815042B (en) Orthogonal frequency division multiplexing (OFDM) system channel estimation method and device
EP1894378A1 (en) Receiver apparatus for receiving a multicarrier signal
CN102571647B (en) Frequency offset estimation method and device
KR20080051984A (en) Method of equalization for tds-ofdm receiver and apparatus thereof
KR100882880B1 (en) Channel estimation system on the basis of be simplified dft for ofdm system and the method thereof
WO2007020943A1 (en) Ofdm communication method
CN100493056C (en) Frequency domain channel estimation method of crossing frequency division multiplexing system with time-domain enveloping weighting
WO2010015101A1 (en) A radio channel model for ici cancellation in multi-carrier systems
CN102780656A (en) Method and device for eliminating multi-symbol subcarrier jamming and performing channel estimation jointly
CN113225292B (en) Method for reducing OFDM peak-to-average ratio by pilot frequency block
CN107566311B (en) Transmission method based on resource block filtering RB F-OFDM system
CN114666190B (en) Channel estimation method based on improved time domain interpolation
CN108924069B (en) OFDM channel estimation method based on dimension reduction DFT
KR100992369B1 (en) Apparatus for estimating channel of ofdm system
CN106789774B (en) Channel estimation methods for multicarrier system
CN108650197B (en) Improved DFT-S-OFDM channel estimation response noise reduction method
CN111245589A (en) Pilot frequency superposition channel estimation method
CN104348765B (en) Channel estimation methods
CN108390837A (en) A kind of LTE down channels method of estimation
KR101492641B1 (en) Method for estimating and compensating channel and receiver using the same
Singh Review of DFT based channel estimation techniques in OFDM over multipath channel

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant