CN101232472A - Method for detecting OFDM signal channel mixed overlaying pilot frequency and data - Google Patents

Method for detecting OFDM signal channel mixed overlaying pilot frequency and data Download PDF

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CN101232472A
CN101232472A CNA200810033927XA CN200810033927A CN101232472A CN 101232472 A CN101232472 A CN 101232472A CN A200810033927X A CNA200810033927X A CN A200810033927XA CN 200810033927 A CN200810033927 A CN 200810033927A CN 101232472 A CN101232472 A CN 101232472A
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data
channel
pilot
subcarrier
coefficient
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张卫兵
曾齐红
管春雷
刘方青
彭之威
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University of Shanghai for Science and Technology
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University of Shanghai for Science and Technology
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Abstract

The invention relates to an OFDM channel detection method for mixing and stacking pilots and data, which includes the following steps: directly stacking the pilot data to the valid data in a comb format; separating the valid data of the corresponding pilot stacking sub-carriers from the terminal with the minimum mean square error algorithm and obtaining the initial detection data of comb frequency coefficient by iterative processing; then implementing a linear interpolation and IFFT processing to the obtained data; accessing and tracking the domain tap from the obtained time-domain channel tap coefficients according to the tap size and obtaining the tap coefficient of L time domains of the channel; and, finally, detecting the channel coefficients of all the sub-carrier locations by interpolation processing of N points of FFT frequency coefficients. The method enables the OFDM transmission system to improve the data utilization rate and save frequency band resources.

Description

The OFDM channel detection method of a kind of pilot tone and data mixing stack
Technical field
The present invention relates to the signal processing method in the radio communication, OFDM (OFDM) channel detection method of particularly a kind of pilot tone and data mixing stack.
Background technology
In mobile ofdm system, the time variation of mobile channel has destroyed the orthogonality between the subcarrier, brings serious inter-carrier interference.Must in time obtain the precise channels estimated parameter in this case, channel detection method commonly used generally directly carries out effective data to be transmitted and pilot data multiplexing at frequency domain, for example, data are transmitted on each different subcarrier respectively with pilot tone, and the pilot data that receives in the receiving terminal utilization detects channel parameter.Because pilot data does not contain any useful data information, so the data utilization ratio of these methods is very low, direct overlapping portion pilot signal can be improved the data utilization ratio of OFDM transmission system greatly on effective transmission data.
Summary of the invention
The objective of the invention is to provide the OFDM channel detection method of a kind of pilot tone and data mixing stack at the problem that prior art exists, be used for estimating time varying channel precise channels parameter information from the subcarrier data of the superimposed pilot data that receive, do not utilize any statistical property of channel, realize high-precision channel parameter detection and tracking, and the channel parameter that utilizes detection to obtain is realized effective channel equalization.
In order to achieve the above object, the invention provides the OFDM channel detection method of a kind of pilot tone and data mixing stack, described ofdm system comprises launch terminal and receiving terminal, the subcarrier that described method is used for the superimposed pilot data that receive from receiving terminal detects the precise channels parameter, it is characterized in that directly being superimposed upon valid data on according to the pectination form pilot data, utilize least-mean-square error algorithm that the valid data on the corresponding pilot tone stack subcarrier are separated at receiving terminal, and the process iterative processing obtains the pectination frequency coefficient initial examination and measurement data of channel, then these data are carried out linear interpolation and inverse fast Fourier transform IFFT processing, the time domain channel tap coefficient that obtains is carried out important tap according to tap magnitude to be obtained and follows the tracks of, obtain L time domain tap coefficient of channel, carry out the channel coefficients that N point quick Fourier conversion FFT frequency coefficient interpolation processing detects all sub-carrier positions at last; The concrete operations step:
(1) it is multiplexing modulating data X and pilot data P to be carried out aliasing according to the pectination form, selects the part subcarrier of sampling pilot tone directly is superimposed upon in the data transmits, and the pilot data power ratio of stack is ρ, and pilot data is P=exp (j2 π kn/N), k ∈ Ω c, Ω wherein cBe the set of sampling sub-carrier positions;
(2) pilot tone and valid data are superposeed multiplexing good data are carried out N point quick Fourier inverse transformation IFFT, and add Cyclic Prefix, carry out radio frequency processing then, and the signal emission is entered wireless mobile channel;
(3) at receiving terminal the signal that receives is carried out the modulus processing and removes Cyclic Prefix, again these data are carried out the fast Fourier transform FFT processing that N is ordered, obtain and the corresponding frequency domain reception of launch terminal subcarrier data;
(4) subcarrier data that receives is separated according to different sub-carrier positions, what will not have the superimposed pilot data directly delivers to channel equalizer, the subcarrier data of pilot data of will having superposeed simultaneously carries out pilot tone superposing type Channel Detection and data separating, mixes receiving data Y from i pilot tone superposed positions subcarrier i=X iH i+ P iH i+ W iIn carry out the initial channel Parameter H iDetect and valid data X iH iSeparate, the course of work of adaptation coefficient adjustment is: the 1. iteration initialization of channel coefficients, the least-squares estimation value that will have data noise is as initial channel coefficients data, even H i(1)=Y i/ P i, 2. produce error signal (k) i=Y- iP iH i(k), wherein k represents the k time iterative processing, 3. according to self adaptation adjusting module H i(k+1)=H i(k)+λ ε i(k) Y iObtain k+1 secondary channel coefficient value, 4. 2. 3. repeating step iterates, and number of iterations can be adjusted according to actual needs, and the error signal that 5. will obtain is at last sent into the channel equalization module as the valid data of separating.Important tap is obtained and tracking cell, be used for sorting according to watt level to handling time domain N the tap coefficient that obtains through inverse fast Fourier transform IFFT, select L prominent tap as important tap, the whole zero setting of other a N-L tap are handled, and wherein L is the length of Cyclic Prefix.
(5) utilize to detect the channel coefficients value that obtains the data that receive are carried out equilibrium treatment, promptly use corresponding reception data directly divided by the channel coefficients value of correspondence.To carry out demultiplexing through the data after the channel equalization and handle, obtaining modulating data will utilize data recovery unit to carry out the demultiplexing processing through the data after the channel equalization, obtain modulating data.
The present invention has following conspicuous outstanding substantive distinguishing features and remarkable advantage compared with prior art:
The present invention has used the self adaptation least-mean-square error algorithm, realize simple, under pilot signal and the incoherent situation of data-signal, can access the Channel Detection parameter of accurate superimposed pilot, use the OFDM transmission system of the inventive method can improve data user rate, save band resource.
Description of drawings
Fig. 1 is for using the OFDM transmission system workflow schematic diagram of the inventive method;
Fig. 2 is the OFDM Channel Detection workflow schematic diagram of pilot tone of the present invention and data mixing stack;
Fig. 3 is transmitting terminal valid data among the present invention and the multiplexing concrete form schematic diagram of pilot data stack;
Embodiment
A preferred embodiment of the present invention is made following detailed description in conjunction with the accompanying drawings:
The specific implementation step of the OFDM channel detection method of this superimposed pilot is as follows:
(1) it is multiplexing modulating data X and pilot data P to be carried out aliasing according to the pectination form, selects the part subcarrier of sampling pilot tone directly is superimposed upon in the data transmits, and the pilot data power ratio of stack is ρ, and pilot data is P=exp (j2 π kn/N), k ∈ Ω c, Ω wherein cBe the set of sampling sub-carrier positions;
(2) pilot tone and valid data are superposeed multiplexing good data are carried out N point quick Fourier inverse transformation IFFT, and add Cyclic Prefix, carry out radio frequency processing then, and the signal emission is entered wireless mobile channel;
(3) at receiving terminal the signal that receives is carried out the modulus processing and removes Cyclic Prefix, again these data are carried out the fast Fourier transform FFT processing that N is ordered, obtain and the corresponding frequency domain reception of launch terminal subcarrier data;
(4) subcarrier data that receives is separated according to different sub-carrier positions, what will not have the superimposed pilot data directly delivers to channel equalizer, and the subcarrier data of the pilot data that will superpose simultaneously carries out pilot tone superposing type channel estimating and data separating.The performing step of pilot tone superposing type Channel Detection and data separating is as follows;
1. mix from i pilot tone superposed positions subcarrier and receive data Y i=X iH i+ P iH i+ W iIn obtain this i the sampling subchannel channel coefficients initial value H i(1)=Y i/ P i
2. for the k time iteration, wherein k is a natural number, will with transmitting terminal corresponding i sampling subcarrier pilot data P=exp (j2 π in/N) and channel coefficients value H i(k) multiply each other, and from receiving data Y iIn deduct these product data PH i(k) obtain error information ε (k) i=Y- iP iH i(k);
3. obtain k+1 secondary channel coefficient value H according to error information i(k+1)=H i(k)+λ ε i(k) Y i, step-length λ selects according to actual conditions;
4. repeating step 2. 3., the number of times of repetition adjusts according to actual conditions;
5. give channel equalizer with the intact error information afterwards of iteration, all sampling sub-carrier channels coefficient values of iteration convergence are carried out linear interpolation processing, obtain the frequency domain channel coefficient value on all subcarriers, then these coefficient values being carried out N point quick Fourier inverse transformation IFFT handles, time domain tap coefficient to the correspondence that obtains sorts according to watt level, select wherein prominent L tap coefficient, remaining whole zero setting, utilize N point quick Fourier conversion FFT frequency coefficient interpolation to handle at last, obtain frequency domain channel coefficient value corresponding on all N the final subcarrier;
(5) the channel coefficients estimated value of utilizing step 4 to obtain is carried out equilibrium treatment to the data that receive, and promptly uses corresponding reception data directly divided by the channel coefficients value of correspondence.To utilize data recovery unit to carry out demultiplexing through the data after the channel equalization handles, obtains modulating data.
Fig. 1 is for using the OFDM transmission system workflow schematic diagram of the inventive method, as shown in Figure 1, it is multiplexing at first modulating data X and pilot data P to be carried out aliasing according to the pectination form, and pilot tone and the valid data multiplexing good data that superpose are carried out N point quick Fourier inverse transformation IFFT, add Cyclic Prefix, carry out radio frequency processing then, the signal emission is entered wireless mobile channel.At receiving terminal the signal that receives is carried out modulus and handle and remove Cyclic Prefix, again these data are carried out the fast Fourier transform FFT processing that N is ordered, obtain receiving subcarrier data with the corresponding frequency domain of launch terminal, then the subcarrier data that receives is separated according to different sub-carrier positions, what will not have the superimposed pilot data directly delivers to channel equalizer, the subcarrier data of pilot data of will having superposeed simultaneously carries out the Channel Detection and the data separating of pilot tone and data mixing stack, calculate the frequency domain channel parameter on each sub-carrier positions, and the data that pilot tone superposes on the sub-carrier positions are effectively separated with pilot tone, the valid data of separating are sent into channel equalizer.Utilize the channel coefficients value calculate that the data that receive are carried out equilibrium treatment at last, promptly use corresponding reception data directly divided by the channel coefficients value of correspondence.To utilize data recovery unit to carry out demultiplexing through the data after the channel equalization and handle, obtaining modulating data will utilize data recovery unit to carry out the demultiplexing processing through the data after the channel equalization, obtain modulating data.
As shown in Figure 2, the OFDM Channel Detection process of the superimposed pilot of present embodiment comprises that mainly the channel coefficients initial examination and measurement is separated with valid data and important tap is obtained and followed the tracks of.At first mix and receive data Y from i pilot tone superposed positions subcarrier i=X iH i+ P iH i+ W iIn obtain this i the sampling subchannel channel coefficients initial value H i(1)=Y i/ P i
Begin iterative processing then, the k time iterative process comprises: will with transmitting terminal corresponding i sampling subcarrier pilot data P=exp (j2 π in/N) and channel coefficients value H i(k) multiply each other, and from receiving data Y iIn deduct these product data PH i(k) obtain error information ε (k) i=Y- iP iH i(k), obtain k+1 secondary channel coefficient value H according to error information i(k+1)=H i(k)+λ ε i(k) Y iNumber of iterations can be adjusted according to actual operating position,
Give channel equalizer with the intact error information afterwards of iteration at last, all sampling sub-carrier channels coefficient values of iteration convergence are carried out linear interpolation processing, obtain the frequency domain channel coefficient value on all subcarriers, then these coefficient values being carried out N point quick Fourier inverse transformation IFFT handles, time domain tap coefficient to the correspondence that obtains sorts according to watt level, select wherein prominent L tap coefficient, remaining whole zero setting, utilize N point quick Fourier conversion FFT frequency coefficient interpolation to handle at last, obtain frequency domain channel coefficient value corresponding on all N the final subcarrier.
As shown in Figure 3, transmitting terminal valid data in the present embodiment and the multiplexing concrete form of pilot data stack depend primarily on the OFDM channel sampling interval, this interval is decided by the transmission environment of reality, can effectively adjust in actual use, the pilot data subcarrier directly is superimposed upon on the valid data according to this sampling interval uniformly, the pilot data power ratio of stack is ρ, and pilot data is P=exp (j2 π kn/N), k ∈ Ω c, Ω wherein cBe the set of sampling sub-carrier positions, all place valid data to be transmitted on other subcarriers.
In sum, the present invention directly directly is superimposed upon valid data on according to the pectination form pilot data, utilize least-mean-square error algorithm that the valid data on the corresponding pilot tone stack subcarrier are separated at receiving terminal, and the process iterative processing obtains the pectination frequency coefficient initial examination and measurement data of channel, then these data are carried out linear interpolation and inverse fast Fourier transform IFFT processing, the time domain channel tap coefficient that obtains is carried out important tap according to tap magnitude to be obtained and follows the tracks of, obtain L time domain tap coefficient of channel, carry out the channel coefficients that N point quick Fourier conversion FFT frequency coefficient interpolation processing calculates all sub-carrier positions at last.Use the OFDM transmission system of the inventive method can improve data user rate, save band resource.

Claims (2)

1. the OFDM channel detection method of pilot tone and data mixing stack, the subcarrier that is used for the superimposed pilot data that receive from receiving terminal detects the precise channels parameter, it is characterized in that directly being superimposed upon valid data on according to the pectination form pilot data, utilize least-mean-square error algorithm that the valid data on the corresponding pilot tone stack subcarrier are separated at receiving terminal, and the process iterative processing obtains the pectination frequency coefficient initial examination and measurement data of channel, then these data are carried out linear interpolation and inverse fast Fourier transform IFFT processing, the time domain channel tap coefficient that obtains is carried out important tap according to tap magnitude to be obtained and follows the tracks of, obtain L time domain tap coefficient of channel, carry out the channel coefficients that N point quick Fourier conversion FFT frequency coefficient interpolation processing detects all sub-carrier positions at last.The concrete operations step is as follows:
A. it is multiplexing modulating data X and pilot data P to be carried out aliasing according to the pectination form, selects the part subcarrier of sampling pilot tone directly is superimposed upon in the data transmits, and the pilot data power ratio of stack is ρ, and pilot data is P=exp (j2 π kn/N), k ∈ Ω c, Ω wherein cBe the set of sampling sub-carrier positions;
B. the multiplexing good data that pilot tone and valid data superposeed are carried out N point quick Fourier inverse transformation IFFT, and add Cyclic Prefix, carry out radio frequency processing then, and the signal emission is entered wireless mobile channel;
C. at receiving terminal the signal that receives is carried out the modulus processing and removes Cyclic Prefix, again these data are carried out the fast Fourier transform FFT processing that N is ordered, obtain and the corresponding frequency domain reception of launch terminal subcarrier data;
D. the subcarrier data that receives is separated according to different sub-carrier positions, what will not have the superimposed pilot data directly delivers to channel equalizer, the subcarrier data of pilot data of will having superposeed simultaneously carries out pilot tone superposing type channel estimating and data separating, and detects the channel coefficients value;
E. the channel coefficients detected value that utilizes step 4 to obtain carries out equilibrium treatment to the data that receive, and promptly uses corresponding reception data directly divided by the channel coefficients value of correspondence.To utilize data recovery unit to carry out demultiplexing through the data after the channel equalization handles, obtains modulating data.
2. the OFDM channel detection method of pilot tone according to claim 1 and data mixing stack, it is characterized in that: the pilot tone superposing type Channel Detection in the described step (4) and the performing step of data separating are as follows;
1. mix from i pilot tone superposed positions subcarrier and receive data Y i=X iH i+ P iH i+ W iIn obtain this i the sampling subchannel channel coefficients initial value H i(1)=Y i/ P i
2. carry out the k time iterative processing, wherein k is a natural number, will with transmitting terminal corresponding i sampling subcarrier pilot data P=exp (j2 π in/N) and channel coefficients value H i(k) multiply each other, and from receiving data Y iIn deduct these product data PH i(k) obtain error information ε (k) i=Y- iP iH i(k);
3. obtain k+1 secondary channel coefficient estimation value H according to error information i(k+1)=H i(k)+λ ε i(k) Y i, step-length λ selects according to actual conditions;
4. repeating step 2. with step 3., the number of times of repetition adjusts according to actual conditions;
5. give channel equalizer with the intact error information afterwards of iteration, all sampling sub-carrier channels coefficient values of iteration convergence are carried out linear interpolation processing, obtain the frequency domain channel coefficient value on all subcarriers, then these coefficient values being carried out N point quick Fourier inverse transformation IFFT handles, time domain tap coefficient to the correspondence that obtains sorts according to watt level, select wherein prominent L tap coefficient, remaining whole zero setting, utilize N point quick Fourier conversion FFT frequency coefficient interpolation to handle at last, obtain frequency domain channel coefficient value corresponding on all N the final subcarrier.
CNA200810033927XA 2008-02-27 2008-02-27 Method for detecting OFDM signal channel mixed overlaying pilot frequency and data Pending CN101232472A (en)

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WO2011140719A1 (en) * 2010-05-14 2011-11-17 Zte Wistron Telecom Ab Method and apparatus for channel estimation in lte
CN102394714A (en) * 2011-08-06 2012-03-28 桂林市思奇通信设备有限公司 Method and system for receiving digital broadcasting signals in frequency modulation (FM) broadcast bands
CN105187100A (en) * 2014-06-06 2015-12-23 索尼公司 MIMO communication method, terminal, and base station apparatus
CN108055222A (en) * 2017-10-30 2018-05-18 捷开通讯(深圳)有限公司 Data processing method and intelligent terminal based on ofdm system
CN109039567A (en) * 2018-08-21 2018-12-18 电子科技大学 A kind of pilot tone of SCMA multiple access system and data investigation transmission method
CN109067674A (en) * 2018-07-10 2018-12-21 电子科技大学 A kind of channel estimation methods based on selected slant stack pilot tone
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CN114070681A (en) * 2021-12-24 2022-02-18 山东大学 Signal recovery method and system based on superimposed pilot cancellation weighted channel estimation
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WO2011140719A1 (en) * 2010-05-14 2011-11-17 Zte Wistron Telecom Ab Method and apparatus for channel estimation in lte
CN102394714A (en) * 2011-08-06 2012-03-28 桂林市思奇通信设备有限公司 Method and system for receiving digital broadcasting signals in frequency modulation (FM) broadcast bands
CN105187100B (en) * 2014-06-06 2020-08-04 索尼公司 MIMO communication method, terminal and base station equipment
CN105187100A (en) * 2014-06-06 2015-12-23 索尼公司 MIMO communication method, terminal, and base station apparatus
CN108055222A (en) * 2017-10-30 2018-05-18 捷开通讯(深圳)有限公司 Data processing method and intelligent terminal based on ofdm system
US11405255B2 (en) 2017-10-30 2022-08-02 JRD Communication (Shenzhen) Ltd. Data processing method and intelligent terminal based on orthogonal frequency division multiplexing (OFDM) system
CN108055222B (en) * 2017-10-30 2020-09-11 捷开通讯(深圳)有限公司 Data processing method based on OFDM system and intelligent terminal
WO2019085913A1 (en) * 2017-10-30 2019-05-09 捷开通讯(深圳)有限公司 Data processing method based on ofdm system, and smart terminal
CN109067674A (en) * 2018-07-10 2018-12-21 电子科技大学 A kind of channel estimation methods based on selected slant stack pilot tone
CN109067674B (en) * 2018-07-10 2021-02-12 电子科技大学 Channel estimation method based on selective superposition pilot frequency
CN109039567B (en) * 2018-08-21 2020-11-13 电子科技大学 Pilot frequency and data superposition transmission method of SCMA (sparse code multiple Access) multiple access system
CN109039567A (en) * 2018-08-21 2018-12-18 电子科技大学 A kind of pilot tone of SCMA multiple access system and data investigation transmission method
CN109194449A (en) * 2018-10-12 2019-01-11 四川大学 The non-orthogonal multiple Transmission system and method for pseudo channel precoding
CN109194449B (en) * 2018-10-12 2020-12-04 四川大学 Virtual channel pre-coding non-orthogonal multiple access transmission system and method
WO2021018120A1 (en) * 2019-07-30 2021-02-04 北京大学 Method for providing bypass network pilot in open radio channel
RU2784459C1 (en) * 2019-07-30 2022-11-25 Пекин Юниверсити Method for providing pilot signal from bypass channel in network with open wireless communication channels
US11888512B2 (en) 2019-07-30 2024-01-30 Peking University Method for piloting from bypass in a network with open wireless channels
CN110808927A (en) * 2019-10-31 2020-02-18 江苏软仪科技股份有限公司 Method for estimating 802.11ax protocol 2x mode channel coefficient
CN113347122A (en) * 2021-05-24 2021-09-03 北京银河信通科技有限公司 Channel estimation method and device
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