CN108600140B - Anti-impulse interference channel estimation method in OFDM system - Google Patents

Anti-impulse interference channel estimation method in OFDM system Download PDF

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CN108600140B
CN108600140B CN201711482761.5A CN201711482761A CN108600140B CN 108600140 B CN108600140 B CN 108600140B CN 201711482761 A CN201711482761 A CN 201711482761A CN 108600140 B CN108600140 B CN 108600140B
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channel estimation
interference
pulse interference
transforming
impulse interference
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CN108600140A (en
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邓湛
罗雷
李俊强
李飞
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Yuanneng Huizhi Beijing Digital Technology Co ltd
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Chongqing University of Post and Telecommunications
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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
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2691—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation involving interference determination or cancellation
    • 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
    • H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking

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Abstract

The invention relates to a channel estimation method for resisting impulse interference in an OFDM (orthogonal frequency division multiplexing) system, belonging to the technical field of power line communication. The method comprises the steps of firstly utilizing a nonlinear pulse interference elimination technology to preprocess a reference symbol to obtain more accurate initial channel estimation, then utilizing a Lauda criterion and the initial channel estimation to reconstruct nonlinear distortion generated in preprocessing and pulse interference which is not inhibited according to the distribution characteristics of noise, removing reconstructed interference items from the reference symbol, and finally obtaining high-precision channel estimation. The invention thoroughly eliminates the nonlinear distortion and the pulse interference which is not inhibited, which are introduced in the channel estimation based on the zero setting, keeps stable performance under various pulse interference occurrence probabilities and various pulse interference intensities, and can achieve the performance equivalent to the channel estimation without pulse interference within 2 times or 2 times of iteration under most pulse interference environments.

Description

Anti-impulse interference channel estimation method in OFDM system
Technical Field
The invention belongs to the technical field of power line communication, and relates to a channel estimation method for resisting impulse interference in an OFDM (orthogonal frequency division multiplexing) system.
Background
Power Line Communication (PLC) is a Communication method for data transmission using a Power Line network as a transmission medium. Because the power line network has the advantages of wide distribution, no need of rewiring, convenience in maintenance and the like, the power line communication is regarded as a solution for solving the problem of the last kilometer of the information highway in recent years, and becomes a research hotspot in the technical field of current communication. However, power lines were not originally designed for data transmission and communication using them requires a number of problems to be solved, such as impulse interference, frequency selective fading, etc. Orthogonal Frequency Division Multiplexing (OFDM) technology can resist frequency selective fading of a channel, fully utilize a frequency band, and realize high-speed data transmission under the condition that the bandwidth of a power line channel is limited, so that the OFDM technology becomes a popular choice for a modulation and demodulation scheme of a current PLC system. In the process of transmitting signals by the PLC system, the signals are distorted and distorted at a receiving end due to the influence of multipath effect of a power line channel, and the correct judgment of the signals can be realized only by carrying out equalization by using a result of channel estimation. However, the power line communication channel has a bad environment, burst interference exists, the duration time is short, the amplitude is high, data on almost all pilot frequency subcarriers are seriously affected after OFDM demodulation, accurate channel estimation cannot be obtained by directly applying a traditional channel estimation algorithm such as LS, LMMSE and the like, and therefore realization of anti-pulse interference channel estimation in a PLC system based on OFDM is very critical.
The nulling method, the clipping method and the combination of the two methods are commonly used as a nonlinear impulse interference cancellation method, and the nulling method is often used in channel estimation for resisting impulse interference because a good compromise is obtained between performance and complexity. However, although the nulling method is simple, it causes non-linear distortion while eliminating impulse interference, and seriously affects the performance of channel estimation. In addition, the method has an optimal threshold value, and a plurality of impulse interferences below the threshold value cannot be restrained, so that the performance is sharply reduced when the probability of the impulse interferences is increased.
Disclosure of Invention
In view of this, the present invention provides a channel estimation method for resisting impulse interference in an OFDM system, which solves the problems of nonlinear distortion and incomplete impulse interference cancellation caused by channel estimation based on nulling under impulse interference in a power line communication system.
In order to achieve the purpose, the invention provides the following technical scheme:
a channel estimation method for resisting impulse interference in an OFDM system comprises the following steps:
s1: receiving a signal from a base station and extracting a reference symbol rn；
S2: to rnThe sampling points with the medium amplitude exceeding the zero setting threshold value T are subjected to zero setting processing to obtain
Figure BDA0001534149910000021
Recording the number of zeroed samples NI；
S3: to pair
Figure BDA0001534149910000022
Performing OFDM demodulation and transforming to frequency domain to obtain
Figure BDA0001534149910000023
S4: performing initial LS channel estimation to obtain
Figure BDA0001534149910000024
S5: transforming the LS estimation result to the time domain to obtain
Figure BDA0001534149910000025
All the samples except the cyclic prefix length L are obtained after setting to zero
Figure BDA0001534149910000026
S6: will be provided with
Figure BDA0001534149910000027
Transforming the frequency domain to obtain the channel frequency response estimation value
Figure BDA0001534149910000028
S7: reference symbol X of local frequency domainkAnd
Figure BDA0001534149910000029
NIthe result of the/N multiplication is from step S3
Figure BDA00015341499100000210
Is subtracted to obtain
Figure BDA00015341499100000211
S8: will be provided with
Figure BDA00015341499100000212
Transforming to the time domain to obtain
Figure BDA00015341499100000213
Then, the nonlinear distortion caused by the zero-set processing in the step S2 and the residual impulse interference sampling points S which are not processed in the step S2 are screened out by utilizing the LayAct criterionn；
S9: for step S3
Figure BDA00015341499100000214
To perform a repair, i.e.
Figure BDA00015341499100000215
S10: returning to the step S4 for iteration, and finally outputting the channel frequency response estimated value after a certain number of iterations
Figure BDA00015341499100000216
The invention has the beneficial effects that: the invention thoroughly eliminates the nonlinear distortion and the pulse interference which is not inhibited, which are introduced in the channel estimation based on the zero setting, keeps stable performance under various pulse interference occurrence probabilities and various pulse interference intensities, and can achieve the performance equivalent to the channel estimation without pulse interference within 2 times or 2 times of iteration under most pulse interference environments.
Drawings
In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:
FIG. 1 is a block diagram of an OFDM based PLC system;
FIG. 2 is a block diagram of joint impulse interference cancellation and iterative channel estimation;
FIG. 3 is a graph of error performance under different pulse interference occurrence probabilities;
FIG. 4 is a graph of error performance under different pulse interference strengths;
FIG. 5 is a plot of channel estimation mean square error;
fig. 6 is a system bit error rate curve.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
1. System model
Consider a system model as shown in figure 1. At a sending end, information bits are subjected to convolutional coding, interleaving and constellation mapping to obtain a modulation symbol XkThen mapping to corresponding sub-carrier respectively to carry out OFDM modulation to obtain baseband sending signal xnAssuming that there are N subcarriers, the time-domain transmission signal in one OFDM symbol period is represented as
Figure BDA0001534149910000031
Coupling the baseband transmission signal to a power line channel through a coupler for transmission, wherein the signal received by a receiving end is represented as
Figure BDA0001534149910000032
Wherein h isnFor channel impulse response, symbols
Figure BDA0001534149910000039
Representing a convolution operation, ηnFrom background noise omeganAnd impulse interference InAnd (4) forming. After receiving the signal at the receiving end, firstly carrying out automatic gain control and synchronization, carrying out channel estimation after OFDM demodulation, carrying out equalization by using an estimation result, then carrying out reverse processing with the transmitting end, and finally outputting the original information bit.
In order to analyze the influence of impulse interference on the channel estimation of the PLC system, the background noise omega is assumednIs a mean of 0 and a variance of
Figure BDA00015341499100000310
The Gaussian white noise and the pulse interference adopt a Bernoulli-Gaussian model and are expressed as
In＝bn·in(3)
Wherein inIs a mean of 0 and a variance of
Figure BDA0001534149910000033
White Gaussian noise of (b)nTo follow the stochastic process of the Bernoulli distribution, the probability density distribution is
Figure BDA0001534149910000034
Wherein p represents the probability of the occurrence of impulse interference, and further defines a signal power to background noise power ratio of
Figure BDA0001534149910000035
Signal power to pulse interference power ratio of
Figure BDA0001534149910000036
The channel frequency response is expressed as
Figure BDA0001534149910000037
Wherein N ispathIs the number of multipaths, gi、diWeight factor and length, a, of the ith path, respectively0And a1For the attenuation parameter, k0Is an index of the decay factor, vpIs the phase velocity of the cable.
2. Joint impulse interference cancellation and iterative channel estimation
1) Receiving a signal from a base station and extracting a reference symbol rnFor r whose amplitude exceeds TnSetting the sampling points to zero and recording the number N of the set-to-zero sampling pointsI
Figure BDA0001534149910000038
Wherein T represents an optimal zeroing threshold of
Figure BDA0001534149910000041
2) To pair
Figure BDA0001534149910000042
Performing OFDM demodulation and transforming to frequency domain to obtain
Figure BDA0001534149910000043
And performs initial LS channel estimation
Figure BDA0001534149910000044
Figure BDA0001534149910000045
3) To pair
Figure BDA0001534149910000046
Processing noise samples beyond the intermediate cyclic prefix length L
Figure BDA0001534149910000047
Figure BDA0001534149910000048
Figure BDA0001534149910000049
4) Nonlinear distortion and residual impulse interference reconstruction
Figure BDA00015341499100000410
Figure BDA00015341499100000411
According to the Lauda criterion, the amplitude | ω of the background noisen|<(μ+3σω) Has a probability of 99.74%, since μ is 0, 3 σ is obtainedωThe nonlinear distortion component and the residual impulse interference component may be screened as thresholds, i.e.
Figure BDA00015341499100000412
5) Receive preamble symbol repair, i.e.
Figure BDA00015341499100000413
6) Returning to the step 2 for iteration, and finally outputting after a certain number of iterations
Figure BDA00015341499100000414
FIG. 2 is a block diagram of joint impulse interference cancellation and iterative channel estimation; FIG. 3 is a graph of error performance under different pulse interference occurrence probabilities; FIG. 4 is a graph of error performance under different pulse interference strengths; FIG. 5 is a plot of channel estimation mean square error; fig. 6 is a system bit error rate curve.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims (1)

1. A channel estimation method for resisting impulse interference in an OFDM system is characterized in that: the method comprises the following steps:
s1: receiving a signal from a base station and extracting a reference symbol rn；
S2: to rnThe sampling points with the medium amplitude exceeding the zero setting threshold value T are subjected to zero setting processing to obtain
Figure FDA0001534149900000011
Recording the number of zeroed samples NI；
S3: to pair
Figure FDA0001534149900000012
Performing OFDM demodulation and transforming to frequency domain to obtain
Figure FDA0001534149900000013
S4: performing initial LS channel estimation to obtain
Figure FDA0001534149900000014
S5: transforming the LS estimation result to the time domain to obtain
Figure FDA0001534149900000015
All the samples except the cyclic prefix length L are obtained after setting to zero
Figure FDA0001534149900000016
S6: will be provided with
Figure FDA0001534149900000017
Transforming the frequency domain to obtain the channel frequency response estimation value
Figure FDA0001534149900000018
S7: reference symbol X of local frequency domainkAnd
Figure FDA0001534149900000019
NIthe result of the/N multiplication is from step S3
Figure FDA00015341499000000110
Is subtracted to obtain
Figure FDA00015341499000000111
S8: will be provided with
Figure FDA00015341499000000112
Transforming to the time domain to obtain
Figure FDA00015341499000000113
Then, the nonlinear distortion caused by the zero-set processing in the step S2 and the residual impulse interference sampling points S which are not processed in the step S2 are screened out by utilizing the LayAct criterionn；
S9: for step S3
Figure FDA00015341499000000114
To perform a repair, i.e.
Figure FDA00015341499000000115
S10: returning to the step S4 for iteration, and finally outputting the channel frequency response estimated value after a certain number of iterations
Figure FDA00015341499000000116
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CN109787656B (en) * 2019-01-25 2021-03-12 北京智芯微电子科技有限公司 Automatic gain control device for OFDM power line communication
CN111669192B (en) * 2020-06-15 2021-06-29 珠海中慧微电子有限公司 Method for identifying and suppressing short-time pulse interference in OFDM signal
CN112866152A (en) * 2021-01-19 2021-05-28 重庆邮电大学 Iterative channel estimation and impulse noise suppression method in OFDM system
CN114584179B (en) * 2022-03-02 2023-07-04 重庆邮电大学 Method for eliminating pulse interference in PLC time domain

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7269234B2 (en) * 2002-06-14 2007-09-11 Siemens Communications, Inc. Arrangement for dynamic DC offset compensation
CN101547174A (en) * 2009-04-30 2009-09-30 中国电子科技集团公司第五十四研究所 Method for phase and symbol synchronization, channel estimation and frequency domain equalization of SC-FDE system
CN103763249A (en) * 2014-01-13 2014-04-30 宁波大学 Anti-interference wireless signal transmission method for digital broadcast
CN105634539A (en) * 2015-12-31 2016-06-01 华为技术有限公司 Interference elimination method and apparatus
CN106209700A (en) * 2016-06-30 2016-12-07 天津工业大学 OFDM compressed sensing channel and non-linear distortion Combined estimator algorithm
CN106664273A (en) * 2014-08-15 2017-05-10 华为技术有限公司 Interference cancellation in MIMO same channel full-duplex transceivers
CN106877907A (en) * 2017-01-09 2017-06-20 北京邮电大学 A kind of anti-noise channel estimation methods in power line

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100656339B1 (en) * 2003-12-26 2006-12-11 한국전자통신연구원 Pulse signal generator for ultra-wide band radio transceiving and radio transceiver having the same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7269234B2 (en) * 2002-06-14 2007-09-11 Siemens Communications, Inc. Arrangement for dynamic DC offset compensation
CN101547174A (en) * 2009-04-30 2009-09-30 中国电子科技集团公司第五十四研究所 Method for phase and symbol synchronization, channel estimation and frequency domain equalization of SC-FDE system
CN103763249A (en) * 2014-01-13 2014-04-30 宁波大学 Anti-interference wireless signal transmission method for digital broadcast
CN106664273A (en) * 2014-08-15 2017-05-10 华为技术有限公司 Interference cancellation in MIMO same channel full-duplex transceivers
CN105634539A (en) * 2015-12-31 2016-06-01 华为技术有限公司 Interference elimination method and apparatus
CN106209700A (en) * 2016-06-30 2016-12-07 天津工业大学 OFDM compressed sensing channel and non-linear distortion Combined estimator algorithm
CN106877907A (en) * 2017-01-09 2017-06-20 北京邮电大学 A kind of anti-noise channel estimation methods in power line

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
OFDM系统的信道估计和信号均衡技术的研究;樊同亮;《中国优秀博士学位论文信息科技辑I136-22》;20130215;全文 *
智能电网窄带OFDM通信系统噪声抑制;谷志茹;《电工技术学报》;20141130;第29卷(第11期);全文 *

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