CN114666190B - Channel estimation method based on improved time domain interpolation - Google Patents
Channel estimation method based on improved time domain interpolation Download PDFInfo
- Publication number
- CN114666190B CN114666190B CN202210276327.6A CN202210276327A CN114666190B CN 114666190 B CN114666190 B CN 114666190B CN 202210276327 A CN202210276327 A CN 202210276327A CN 114666190 B CN114666190 B CN 114666190B
- Authority
- CN
- China
- Prior art keywords
- pilot
- channel estimation
- interpolation
- subcarriers
- channel
- 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.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 33
- 239000000969 carrier Substances 0.000 claims description 6
- 230000000295 complement effect Effects 0.000 claims description 4
- 238000005070 sampling Methods 0.000 claims description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000004422 calculation algorithm Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000009795 derivation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
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 cannot flexibly select pilot frequency 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 pilot frequencies and the channel estimation on subcarriers is reduced, and the method has higher use flexibility; has lower complexity and is easy to realize.
Description
Technical Field
The present disclosure relates to the field of wireless communications, and in particular, to a channel estimation method based on improved time domain interpolation.
Background
The Orthogonal Frequency Division Multiplexing (OFDM) technology is a parallel multi-carrier modulation technology, has better multi-path interference resistance and spectrum utilization efficiency, and has wide application. Channel estimation is one of the key technologies of OFDM, in which a received signal is distorted due to the influence of channel characteristics, and in order to recover transmitted information, the influence of a channel needs to be estimated at a receiver.
The pilot-based channel estimation methods include least square method (LS), minimum mean square error method (MMSE), and the like. LS channel estimation has larger error, but has low calculation complexity, does not need priori knowledge of the channel, and has wide application; MMSE channel estimation, although improving the algorithm accuracy to some extent, brings about a great computational overhead. The LS channel estimation method for inserting the pilot frequency in the frequency domain firstly obtains the channel estimation value of the pilot frequency, and then obtains the channel estimation values of all sub-carriers through 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 through a Fast Fourier Transform (FFT) algorithm, and has lower complexity.
The time domain interpolation is used under the condition that the pilot is equally spaced and the number of subcarriers is an integer multiple of the pilot spacing. While for pilots inserted in the frequency domain, the pilot interval is determined by the maximum delay of the Channel Impulse Response (CIR), for channels with large delay spread, the pilot used for channel estimation consumes a lot of subcarrier resources. The 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 integer multiple of the pilot interval, the time-domain interpolation may need to select a smaller pilot interval, thereby increasing the overhead of the pilot number.
Disclosure of Invention
The application provides a channel estimation method based on improved time domain interpolation, which aims at flexibly selecting pilot frequency intervals in time domain interpolation in OFDM channel estimation.
The technical aim of the application is achieved through the following technical scheme:
a channel estimation method based on improved time domain interpolation, comprising:
step 1, determining the number N of sub-carriers and the number N of pilot frequencies P And pilot interval m, insert pilot equidistant, and the first pilot is inserted into the position of the first subcarrier;
step 2, estimating the channels at all pilot frequencies by a least square method to obtain channel estimation values at the pilot frequenciesThen->Length of N P The method comprises the steps of carrying out a first treatment on the surface of the Wherein i represents the number of the pilot frequency;
step 3, carrying out linear interpolation on the subcarriers to obtain linear interpolation results of all the subcarriersThenIs N in length; wherein k represents the number of the subcarrier;
step 4, forPerforming inverse fast Fourier transform of N points to obtain a first channel impulse response estimation result +.>Then->Is N in length; wherein n represents the sampling order in the time domain;
step 5, forFront N of (3) P Correction is carried out to obtain a second channel impulse response estimation result +.>ThenLength of N P ；
Step 6, atTail complement (N-N) P ) Zero, get->Then->Is N in length;
step 7, forPerforming N-point fast Fourier transform to obtain channel estimation values of all subcarriers>
Further, in the step 2, the channel estimation value at the pilot frequency is a result obtained by dividing the signal received after the pilot frequency passes through the channel with the pilot frequency symbol sent by the transmitter of the corresponding subcarrier.
Further, in the step 3, performing linear interpolation on the subcarriers includes: the interpolation of the sub-carriers between the first pilot position and the last pilot position is performed by estimating the channel estimate at the pilotLinear interpolation is carried out to obtain interpolation results of subcarriers outside the last pilot frequency position, and the interpolation results are obtained through channel estimation values at the last 2 pilot frequencies;
channel estimation at last 2 pilots isAnd->Then:
by passing throughAnd->Performing linear interpolation to obtain interpolation results of subcarriers outside the last pilot frequency position;
the linear interpolation result for all subcarriers is expressed as:
obtained byLength of (2) is mN P Retaining mN only P The first N results in (a) as +.>
Further, in the step 5, forFront N of (3) P The correction includes:
wherein,<3/4·N P >represents greater than or equal to 3/4.N P Is a minimum integer of (a).
Further, in the step 6Tail complement (N-N) P ) Zero, comprising:
the beneficial effects of this application lie in: the method and the device realize approximate time domain interpolation by utilizing the linear interpolation of the subcarrier channel estimation result, and have higher interpolation precision on the basis of the linear interpolation result, thereby providing interpolation precision similar to the time domain interpolation; 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 pilot frequencies and the channel estimation on subcarriers is reduced, and the method has higher use flexibility; has lower complexity and is easy to realize.
Drawings
FIG. 1 is a flow chart of a method described herein;
fig. 2 is a graph of Bit Error Rate (BER) simulations of the present application at different signal-to-noise ratios (SNRs).
Detailed Description
The technical scheme of the application will be described in detail below with reference to the accompanying drawings.
Aiming at the problem that pilot frequency intervals cannot be flexibly selected in time domain interpolation in OFDM channel estimation, linear interpolation is carried out on subcarrier channel estimation results, approximate time domain interpolation is realized on the basis of the linear interpolation results, and flexible selection of the pilot frequency intervals can be realized.
Example 1:
a channel estimation method based on improved time domain interpolation is realized by a flow chart shown in fig. 1, and the calculation steps are as follows:
the channel impulse response of the channel to be estimated in the application is as follows:
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 frequency interval is 5, the pilot frequency is inserted at equal intervals, and the first pilot frequency is placed at the position of the first subcarrier, and the number of the pilot frequencies is 205.
Step 2, estimating the channels at all pilot frequencies by a least square method to obtain channel estimation values at the pilot frequenciesIs 205, 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 allLinear interpolation result of sub-carrierIs 1024, k is the number of subcarriers.
In particular, a specific derivation of the linear interpolation is as follows:
for linear interpolation of the subcarrier whose subcarrier number is after the last pilot, it is provided thatThe method comprises the following steps:
obtaining interpolation results of all subcarriers:
obtained byIs 1025, only the first 1024 results are retained.
Step 4, forPerforming 1024-point IFFT to obtain CIR (channel impulse response) estimation result ∈>n is the sampling order in the time domain.
Step 5, forFront N of (3) P Correction is performed to obtain a more accurate (CIR) estimation result +.>Is 205.
Specifically, toThe specific deduction form of the treatment is as follows:
step 6, atIs supplemented with 819 zeros to obtain +.>Then->Is 1024 in length;
specifically, the specific derivation of zero padding is as follows:
step 7, forPerforming 1024-point FFT to obtain channel estimation values +.>
Under the condition that the pilot frequency interval m is 4 and 6, the corresponding pilot frequency number is 256 and 171, and the steps 2-7 are repeated to obtain the corresponding pilot frequency
Fig. 2 shows BER performance results of linear interpolation (pilot interval 4), time domain interpolation (pilot interval 4), and the present application (pilot intervals 4, 5, 6) under the same parameter configuration. As can be seen from fig. 2, the method is superior to linear interpolation, and has the same performance as time domain interpolation when the pilot interval is 4, and the performance is slightly reduced when the pilot intervals are 5 and 6, but still has better precision.
When the pilot frequency interval is 5, compared with time domain interpolation, the application reduces the use of 51 pilot frequencies; at a pilot spacing of 6, the application reduces the use of 85 pilots compared to time-domain interpolation. The pilot frequency interval can be flexibly selected according to the precision requirement and the resource consumption.
The foregoing description of the preferred embodiments of the present application is not intended to be limiting, but is intended to cover any and all modifications, equivalents, and alternatives falling within the spirit and principles of the present application.
Claims (4)
1. A channel estimation method based on improved time domain interpolation, comprising:
step 1, determining the number N of sub-carriers and the number N of pilot frequencies P And pilot interval m, insert pilot equidistant, and the first pilot is inserted into the position of the first subcarrier;
step 2, estimating the channels at all pilot frequencies by a least square method to obtain channel estimation values at the pilot frequenciesThen->Length of N P The method comprises the steps of carrying out a first treatment on the surface of the Wherein i represents the number of the pilot frequency;
step 3, carrying out linear interpolation on the subcarriers to obtain linear interpolation results of all the subcarriersThen->Is N in length; wherein k represents the number of the subcarrier;
step 4, forPerforming inverse fast Fourier transform of N points to obtain a first channel impulse response estimation result +.>Then->Is N in length; wherein n represents the sampling order in the time domain;
step 5, forFront N of (3) P Correction is carried out to obtain a second channel impulse response estimation result +.>Then->Length of N P ；
Step 6, atTail complement (N-N) P ) Zero, get->Then->Length of (2)Is N;
step 7, forPerforming N-point fast Fourier transform to obtain channel estimation values of all subcarriers>
In the step 3, the linear interpolation of the subcarriers includes: the interpolation of the sub-carriers between the first pilot position and the last pilot position is performed by estimating the channel estimate at the pilotLinear interpolation is carried out to obtain interpolation results of subcarriers outside the last pilot frequency position, and the interpolation results are obtained through channel estimation values at the last 2 pilot frequencies;
channel estimation at last 2 pilots isAnd->Then:
by passing throughAnd->Performing linear interpolation to obtain interpolation results of subcarriers outside the last pilot frequency position;
the linear interpolation result for all subcarriers is expressed as:
obtained byLength of (2) is mN P Retaining mN only P The first N results in (a) as +.>
2. The method of channel estimation according to claim 1, wherein in the step 2, the channel estimation value at the pilot is a result of dividing a signal received after the channel at the pilot by pilot symbols transmitted by the transmitter of the corresponding subcarrier.
3. The channel estimation method according to claim 2, wherein in step 5, forFront N of (3) P The correction includes:
wherein,<3/4·N P >represents greater than or equal to 3/4.N P Is a minimum integer of (a).
4. The channel estimation method according to claim 3, wherein in said step 6, inTail complement (N-N) P ) Zero, comprising:
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 CN114666190A (en) | 2022-06-24 |
| CN114666190B true 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)
| 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 |
-
2022
- 2022-03-21 CN CN202210276327.6A patent/CN114666190B/en active Active
Patent Citations (4)
| 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)
| Title |
|---|
| LTE-A系统中基于小区参考信号的信道估计算法;李慧敏;张治中;李琳潇;;计算机应用(07);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114666190A (en) | 2022-06-24 |
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 | |
| JP4472771B2 (en) | Receiver for receiving a multicarrier signal | |
| CN110868369B (en) | Uplink channel estimation method and device based on 5G NR system | |
| KR100896654B1 (en) | Apparatus and method for estimating delay spread of multi-path fading channel in ofdm system | |
| US8374266B2 (en) | Iterative channel estimation method and apparatus for ICI cancellation in multi-carrier | |
| KR101398393B1 (en) | Inter-Carrier Interference Cancellation for ＯＦＤＭＡ Systems | |
| KR101291683B1 (en) | Method of equalization for TDS-OFDM receiver and apparatus thereof | |
| CN101815042B (en) | Orthogonal frequency division multiplexing (OFDM) system channel estimation method and device | |
| CN106888178B (en) | A kind of OFDM/OQAM system channel estimation method | |
| CN102571647B (en) | Frequency offset estimation method and device | |
| KR100882880B1 (en) | Channel estimation system on the basis of be simplified dft for ofdm system and the method thereof | |
| WO2010015101A1 (en) | A radio channel model for ici cancellation in multi-carrier systems | |
| CN100493056C (en) | Frequency domain channel estimation method of crossing frequency division multiplexing system with time-domain enveloping weighting | |
| Yalcin et al. | Low-complexity channel estimation for OFDM systems in high-mobility fading channels | |
| CN114666190B (en) | Channel estimation method based on improved time domain interpolation | |
| CN113225292B (en) | Method for reducing OFDM peak-to-average ratio by pilot frequency block | |
| Aida et al. | LMMSE channel estimation for block-pilot insertion in OFDM systems under time varying conditions | |
| CN108809868B (en) | Channel estimation method and system based on 5G communication network | |
| CN106789774B (en) | Channel estimation methods for multicarrier system | |
| KR100992369B1 (en) | Apparatus for estimating channel of ofdm system | |
| Khan et al. | A novel channel estimation error minimizing interpolation technique for OFDM systems | |
| Adegbite et al. | A selective control information detection scheme for OFDM receivers | |
| Mahmoud et al. | Kalman filter channel estimation based on Comb-type pilots for OFDM system in time and frequency-selective fading environments | |
| Hossain et al. | DFT Based Channel Estimation Analysis in OFDM Supported Wireless Communication system |
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 |