CN102006248A - Multi-carrier based channel estimation method and device as well as application thereof - Google Patents
Multi-carrier based channel estimation method and device as well as application thereof Download PDFInfo
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- CN102006248A CN102006248A CN2010105703490A CN201010570349A CN102006248A CN 102006248 A CN102006248 A CN 102006248A CN 2010105703490 A CN2010105703490 A CN 2010105703490A CN 201010570349 A CN201010570349 A CN 201010570349A CN 102006248 A CN102006248 A CN 102006248A
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Abstract
The invention relates to multi-carrier based channel estimation method and device as well as application thereof. The corresponding method comprises the following steps of: extracting a frequency domain receiving signal of a pilot frequency position, and carrying out initial channel estimation to obtain an initial channel frequency domain response of the pilot frequency position; carrying out frequency domain interpolation on the initial channel frequency domain response to obtain a channel frequency domain response; calculating a channel impulse response according to the channel frequency domain response; carrying out noise suppression on the channel impulse response; and calculating to obtain a final estimated value according to the channel impulse response without virtual carrier influence. The invention reduces the effective diameter of the channel impulse response without the virtual carrier influence by utilizing an inverse matrix of a cyclic convolution matrix of the channel impulse response with virtual carriers before a time domain suppresses noises and partially suppresses the noises, thereby obtaining better channel estimation property.
Description
Technical field
The invention belongs to the wireless communication technique field, relate to a kind of channel estimation methods, device and application based on multicarrier.
Background technology
OFDM (Orthogonal Frequency Division Multiplexing, orthogonal frequency division multiplexi) has higher band efficiency and good anti-multipath performance because of it, being written into standards such as WiMAX, LTE, is the core technology of future broadband wireless communication systems physical layer.And channel estimating is a key technology in the ofdm system, and channel estimation errors will make the error rate increase, and makes system performance degradation.
In real system, for fear of the zone of roll-offing of filter frequency domain response signal is caused distortion, usually that the part carrier wave of transmission bandwidth is vacant as the protection frequency band.Traditional DFT (Discrete Fourier Transform, discrete Fourier transform) algorithm makes its performance be better than channel estimation methods based on criterion of least squares (LS) by carry out Noise Suppression in time domain.But channel impulse response effective diameter energy leaks to some extent when having virtual carrier in the system, therefore can make that also a part of effective energy is suppressed when suppressing noise, makes performance impaired.Especially work as virtual carrier quantity more for a long time, performance can be had a strong impact on.
Summary of the invention
The present invention by the problem of traditional DFT algorithm poor-performing when time domain is carried out noise suppressed, provides a kind of channel estimation methods based on multicarrier, device and application for solving in existing channel estimation technique, and corresponding method comprises:
Extract the frequency domain received signal of pilot frequency locations, and carry out initial channel estimation, obtain pilot frequency locations initial channel frequency domain response;
Described channel frequency domain response is carried out frequency domain interpolation, obtain channel frequency domain response;
According to described channel frequency domain response calculating channel impulse response;
Described channel impulse response is carried out noise suppressed;
Channel impulse response according to described no virtual carrier influence calculates the final estimated value of acquisition.
Corresponding device thereof comprises:
The initial estimation unit is used to extract the frequency domain received signal of pilot frequency locations, and carries out initial channel estimation, obtains pilot frequency locations initial channel frequency domain response;
Frequency domain interpolation unit is used for described channel frequency domain response is carried out frequency domain interpolation, obtains channel frequency domain response;
The impulse response computing unit is used for according to described channel frequency domain response calculating channel impulse response;
Noise suppression unit is used for described channel impulse response is carried out noise suppressed;
Final estimation unit is used for calculating the final estimated value of acquisition according to the channel impulse response of described no virtual carrier influence.
Based on the application of corresponding device thereof, be used for that the single-shot list is received, single-shot is overcharged, multiple single the receipts or the MIMO system.
The present invention is before time domain suppresses noise, the inverse matrix of the channel impulse response convolution matrix when there is virtual carrier in utilization has been reduced the effective diameter of the channel impulse response of no virtual carrier when influencing, and noise section curbed, thereby obtain better channel estimating performance.
Description of drawings
Fig. 1 is the schematic flow sheet based on the channel estimation methods of multicarrier that embodiments of the invention provide;
Fig. 2 is the simulation result schematic diagram that carries out channel estimating in a typical multiple-carrier multiple-antenna system that embodiments of the invention provide;
Fig. 3 is the structural representation based on the channel estimating apparatus of multicarrier that embodiments of the invention provide.
Embodiment
The specific embodiment of the present invention provides a kind of channel estimation methods based on multicarrier, and as shown in Figure 1, this method specifically can comprise:
The basic principle of present embodiment is before time domain suppresses noise, utilizes the inverse matrix of the channel impulse response convolution matrix when having virtual carrier to reduce the effective diameter of the channel impulse response of no virtual carrier when influencing, and noise section is curbed.
Concrete, at transmitting terminal, can insert pilot tone in the available subcarrier pilot frequency locations, data are inserted in all the other available subcarrier positions, and the zero setting of virtual carrier position is through behind the inverse fourier transform, add Cyclic Prefix and form transmit frame, through sending by transmitting antenna after filtering and the up-conversion.
At receiving terminal, at first calculate the channel impulse response convolution matrix when having virtual carrier.When having virtual carrier, because the virtual carrier position all is zero, be equivalent to frequency domain response and window function multiplies each other, this window function is:
Above-mentioned window function is carried out Fu Li leaf inverse transformation obtains impulse response W, can obtain its convolution matrix by cyclic shift:
Because the channel effective diameter only is present in the CP scope, so matrix
CP is capable before only keeping.
Then, extract the frequency domain received signal of the corresponding pilot frequency locations of every transmitting antenna, every transmitting antenna is carried out preliminary frequency domain channel respectively to be estimated, carry out interpolation according to the channel frequency domain response of every transmitting antenna pilot frequency locations again, obtain the frequency domain response of the every whole available subcarriers of transmitting antenna respectively
Carry out Fu Li leaf inverse transformation based on frequency domain response, obtain the channel impulse response of every transmitting antenna respective channels
With channel impulse response
With matrix
Multiply each other and obtain channel impulse response after the noise suppressed
That is:
Afterwards, again with the channel time domain impulse response
Carry out Fourier Tranform and obtain final estimated value
Be the validity that example illustrates the channel estimation methods of the edge subcarrier replacement that the present invention proposes with a typical multiple-carrier multiple-antenna system below.The antenna configurations of supposing the system is 8 transmitting antennas and 8 reception antennas, i.e. N
T=8, N
R=8.Adopt the OFDM modulation system that whole 122.88MHz bandwidth is divided into 2048 subcarriers, wherein 1280 subcarriers are useful subcarrier, and all the other 768 subcarriers are virtual carrier.
At transmitting terminal, be 4 to insert known pilot at first at frequency domain with pilot interval, wherein, per 2 transmit antennas take one group of carrier wave, and all the other useful sub-carrier positions are inserted data, the zero padding of virtual carrier position; Carry out inverse fourier transform then, obtain time-domain signal; Form frame after adding Cyclic Prefix at last, after the filtering up-conversion, send by transmitting antenna.
At receiving terminal, at first calculate channel impulse response convolution matrix W when having virtual carrier according to system parameters.All reception antennas adopt identical channel estimation methods then.Again the frequency pilot sign that extracts is divided by with local pilot frequency sequence and obtains initial frequency domain estimation; Carry out the frequency domain linear interpolation and obtain the channel estimation value of whole available carrier wave
With carrying out inverse fourier transform after the zero padding of above-mentioned estimated result virtual carrier part, obtain channel impulse response
With the time domain impulse response
With matrix
Multiply each other and obtain time domain impulse response after the noise suppressed
After all the other position zero setting, carry out Fourier transform, obtain final channel estimation results
It is 2.45GHz that the system of emulation adopts carrier frequency, and bandwidth is 122.88MHz, sub-carrier number 2048; wherein the available carrier wave number is 1280,64 direct current protecting carrier waves, and the pilot tone frequency domain is spaced apart 4; choose the channel parameter of jakes model, the speed of a motor vehicle is 0.1km/h, and prefix length is greater than maximum multipath time delay.Simulation result can be with reference to figure 2, and when signal to noise ratio (snr) was 20dB, the channel estimation methods mean square error (MSE) that present embodiment provides can reach 1 * 10
-3, and initial channel estimation MSE is 3 * 10
-3,, rise to 10 on the contrary through MSE behind the inverse fourier transform inhibition noise simultaneously because of virtual carrier exists
-2Simulation result shows that the channel estimation methods of present embodiment is chosen the frequency domain estimation and time domain evaluated error least part makes up, and can effectively suppress the evaluated error at virtual carrier edge, improves precision of channel estimation.
Embodiments of the invention also provide a kind of channel estimating apparatus based on multicarrier, as shown in Figure 3, specifically can comprise initial estimation unit 31, frequency domain interpolation unit 32, impulse response computing unit 33, noise suppression unit 34 and final estimation unit 35, initial estimation unit 31 is used to extract the frequency domain received signal of pilot frequency locations, and carry out initial channel estimation, obtain pilot frequency locations initial channel frequency domain response; Frequency domain interpolation unit 32 is used for channel frequency domain response is carried out frequency domain interpolation, obtains channel frequency domain response; Impulse response computing unit 33 is used for according to channel frequency domain response calculating channel impulse response; Noise suppression unit 34 is used for channel impulse response is carried out noise suppressed; Final estimation unit 35 is used for calculating the final estimated value of acquisition according to the channel impulse response of no virtual carrier influence.
Further, in initial estimation unit 31, initial channel estimation comprises frequency domain the least square estimation method, frequency domain least mean-square error method of estimation or frequency domain maximum Likelihood; In frequency domain interpolation unit 32, frequency domain interpolation comprises first-order linear interpolation or second order interpolation high-order interpolation.
In addition, in noise suppression unit 34, comprise inverse matrix product subelement, be used for the inverse matrix of the channel impulse response convolution matrix of channel impulse response when having virtual carrier is multiplied each other, the channel impulse response when obtaining not having virtual carrier and influencing.
The channel estimating apparatus based on multicarrier that present embodiment provides can be used for overcharging (SIMO) at single-shot list receipts (SISO), single-shot, multiple single ofdm system of receiving (MISO) or MIMO (MIMO) carries out channel estimating, the channel estimation process of narrating among its principle and the method embodiment is similar, the evaluated error that can effectively suppress the virtual carrier edge improves precision of channel estimation.
The embodiment of the processing capacity of each unit that comprises in the said apparatus is described in method execution mode before, no longer is repeated in this description at this.
The above; only be the preferable embodiment of the present invention; these embodiments all are based on the different implementations under the general idea of the present invention; and protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claims.
Claims (9)
1. the channel estimation methods based on multicarrier is characterized in that, comprising:
Extract the frequency domain received signal of pilot frequency locations, and carry out initial channel estimation, obtain pilot frequency locations initial channel frequency domain response;
Described channel frequency domain response is carried out frequency domain interpolation, obtain channel frequency domain response;
According to described channel frequency domain response calculating channel impulse response;
Described channel impulse response is carried out noise suppressed;
Channel impulse response according to described no virtual carrier influence calculates the final estimated value of acquisition.
2. method according to claim 1 is characterized in that, described initial channel estimation comprises frequency domain the least square estimation method, frequency domain least mean-square error method of estimation or frequency domain maximum Likelihood.
3. method according to claim 1 is characterized in that, described frequency domain interpolation comprises first-order linear interpolation or second order interpolation high-order interpolation.
4. according to any described method of claim 1 to 3, it is characterized in that, described noise suppressed comprises that the inverse matrix with the channel impulse response convolution matrix of described channel impulse response when having virtual carrier multiplies each other, the channel impulse response when obtaining not having virtual carrier and influencing.
5. the channel estimating apparatus based on multicarrier is characterized in that, comprising:
The initial estimation unit is used to extract the frequency domain received signal of pilot frequency locations, and carries out initial channel estimation, obtains pilot frequency locations initial channel frequency domain response;
Frequency domain interpolation unit is used for described channel frequency domain response is carried out frequency domain interpolation, obtains channel frequency domain response;
The impulse response computing unit is used for according to described channel frequency domain response calculating channel impulse response;
Noise suppression unit is used for described channel impulse response is carried out noise suppressed;
Final estimation unit is used for calculating the final estimated value of acquisition according to the channel impulse response of described no virtual carrier influence.
6. device according to claim 5 is characterized in that, in the initial estimation unit, described initial channel estimation comprises frequency domain the least square estimation method, frequency domain least mean-square error method of estimation or frequency domain maximum Likelihood.
7. device according to claim 5 is characterized in that, in frequency domain interpolation unit, described frequency domain interpolation comprises first-order linear interpolation or second order interpolation high-order interpolation.
8. according to any described device of claim 5 to 7, it is characterized in that, in noise suppression unit, comprise:
Inverse matrix product subelement is used for the inverse matrix of the channel impulse response convolution matrix of described channel impulse response when having virtual carrier is multiplied each other, the channel impulse response when obtaining not having virtual carrier and influencing.
9. based on the application of any described channel estimating apparatus based on multicarrier of claim 5 to 9, it is characterized in that described device is used for that the single-shot list is received, single-shot is overcharged, multiple single the receipts or the MIMO system.
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| CN104506468A (en) * | 2015-01-09 | 2015-04-08 | 南京理工大学 | Time domain sparse channel estimation method |
| CN107171989A (en) * | 2017-07-10 | 2017-09-15 | 东南大学 | Channel estimation methods based on DFT in visible light communication system |
| CN110568439A (en) * | 2019-09-25 | 2019-12-13 | 中南大学 | Impulse type through-wall radar antenna ringing suppression method based on deconvolution |
| CN112995072A (en) * | 2019-12-16 | 2021-06-18 | 广州海格通信集团股份有限公司 | Channel estimation method, device, computer equipment and storage medium |
| CN113595945A (en) * | 2021-08-04 | 2021-11-02 | 重庆邮电大学 | Channel estimation method suitable for PDSCH of 5G system |
| CN114629750A (en) * | 2020-12-10 | 2022-06-14 | 宸芯科技有限公司 | Channel estimation enhancement method, device, equipment and medium |
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|---|---|---|---|---|
| CN104506468A (en) * | 2015-01-09 | 2015-04-08 | 南京理工大学 | Time domain sparse channel estimation method |
| CN107171989A (en) * | 2017-07-10 | 2017-09-15 | 东南大学 | Channel estimation methods based on DFT in visible light communication system |
| CN110568439A (en) * | 2019-09-25 | 2019-12-13 | 中南大学 | Impulse type through-wall radar antenna ringing suppression method based on deconvolution |
| CN110568439B (en) * | 2019-09-25 | 2023-08-22 | 中南大学 | Deconvolution-based impulse type through-wall radar antenna ringing suppression method |
| CN112995072A (en) * | 2019-12-16 | 2021-06-18 | 广州海格通信集团股份有限公司 | Channel estimation method, device, computer equipment and storage medium |
| CN112995072B (en) * | 2019-12-16 | 2022-07-15 | 广州海格通信集团股份有限公司 | Channel estimation method, device, computer equipment and storage medium |
| CN114629750A (en) * | 2020-12-10 | 2022-06-14 | 宸芯科技有限公司 | Channel estimation enhancement method, device, equipment and medium |
| CN113595945A (en) * | 2021-08-04 | 2021-11-02 | 重庆邮电大学 | Channel estimation method suitable for PDSCH of 5G system |
| CN113595945B (en) * | 2021-08-04 | 2023-06-30 | 重庆邮电大学 | Channel estimation method suitable for PDSCH of 5G system |
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Application publication date: 20110406 |