CN101707574B - Channel estimation method and device - Google Patents
Channel estimation method and device Download PDFInfo
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- CN101707574B CN101707574B CN 200910241248 CN200910241248A CN101707574B CN 101707574 B CN101707574 B CN 101707574B CN 200910241248 CN200910241248 CN 200910241248 CN 200910241248 A CN200910241248 A CN 200910241248A CN 101707574 B CN101707574 B CN 101707574B
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Abstract
The invention relates to a channel estimation method and a channel estimation device, and belongs to the technical field of wireless communication. The method and the device solve the problem of higher computation complexity and serious estimation error of a marginal carrier when a virtual carrier exists in the traditional channel estimation method. The method comprises the following steps: performing the channel estimation of an initial frequency domain according to pilot frequency; performing the interpolation estimation of the frequency domain according to a channel estimation result of the initial frequency domain; performing time-domain noise reduction according to the pilot frequency; and selecting an interpolation estimation result of the frequency domain which is greater than a threshold value to replace a result after time-domain noise reduction. The method and the device can acquire the more accurate channel estimation result by comparing the interpolation estimation result of the frequency domain with the result after the time-domain noise reduction and combining the minimum part of the error, and the estimated computation complexity is lower.
Description
Technical field
The present invention relates to a kind of channel estimation methods and device, belong to wireless communication technology field.
Background technology
Orthogonal frequency division multiplexi (OFDM) has been written into the standards such as WiMAX, LTE because it has higher band efficiency and good anti-multipath performance, is the core technology of future broadband wireless communication systems physical layer.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 partial carrier wave of transmission bandwidth is vacant as guard band.Owing to protecting the existence of frequency range, destroyed the orthogonality of pilot tone, reduced channel estimating performance, therefore need the more rational pilot frequency sequence of design and more high-precision receiving terminal algorithm.At present, mainly be based on the channel estimation methods of criterion of least squares (LS) for the channel estimation methods of the multiple antenna and carrier system under the virtual carrier existence, optimum pilot design and the channel estimation methods of windowing improve channel estimation errors.
Therefore, in existing channel estimation methods, there is the problem that computation complexity is higher and estimated accuracy is relatively poor.
Summary of the invention
The invention provides a kind of channel estimation methods and device, to solve in existing channel estimation methods, have the problem that computation complexity is higher and estimated accuracy is relatively poor.
A kind of channel estimation methods comprises:
Carry out initial channel estimation in frequency domain according to pilot tone;
Carrying out frequency domain interpolation according to described initial channel estimation in frequency domain result estimates;
Carrying out time domain noise reduction according to described pilot tone processes;
Choose the poor result less than replacing based on the estimated result of time domain evaluated error after time domain noise reduction is processed of the channel estimating that satisfies frequency domain and interpolation in the virtual carrier position.
A kind of channel estimating apparatus comprises:
The initial channel estimation unit is used for carrying out initial channel estimation in frequency domain according to pilot tone;
Frequency domain interpolation unit is used for carrying out frequency domain interpolation according to described initial channel estimation in frequency domain result and estimates;
The time domain noise reduction processing unit is used for carrying out time domain noise reduction according to described pilot tone and processes;
The estimated result determining unit is used for choosing the poor result less than replacing based on the estimated result of time domain evaluated error after time domain noise reduction is processed of channel estimating that frequency domain and interpolation are satisfied in the virtual carrier position.
The present invention passes through the result after relatively frequency domain interpolation estimation and the time domain noise reduction processing, and the error least part is made up, and can obtain more accurate channel estimation results, and the computation complexity of estimation is lower.
Description of drawings
Fig. 1 is the schematic flow sheet of a kind of channel estimation methods of providing of the specific embodiment of the present invention;
Fig. 2 is the structural representation of a kind of channel estimating apparatus of providing of the specific embodiment of the present invention.
Embodiment
The specific embodiment of the present invention provides a kind of channel estimation methods, comprises according to pilot tone carrying out initial channel estimation in frequency domain; Carrying out frequency domain interpolation according to initial channel estimation in frequency domain result estimates; Carrying out time domain noise reduction according to pilot tone processes; Choose the poor result less than replacing based on the estimated result of time domain evaluated error after time domain noise reduction is processed of the channel estimating that satisfies frequency domain and interpolation in the virtual carrier position.
Further, corresponding initial channel estimation in frequency domain can adopt frequency domain least-squares estimation, frequency domain least mean-square error to estimate or the frequency domain maximal possibility estimation; Corresponding frequency domain interpolation can comprise first-order linear interpolation, second order interpolation or high-order interpolation; Corresponding time domain noise reduction is processed the method that can adopt time domain least-squares estimation, the estimation of time domain least mean-square error, time domain maximal possibility estimation or estimate based on Fourier transform.
And, choose the channel estimating that satisfies frequency domain and interpolation in the virtual carrier position poor less than can comprising channel estimation errors on each subcarrier that more initial channel estimation in frequency domain and time domain channel estimate based on the estimated result of time domain evaluated error as final estimated result, and choose the less result of virtual carrier edge sub-carrier channels evaluated error as final estimated result.
The technical scheme that this embodiment provides is applicable to the single-shot list and receives (SISO), single-shot is received (SIMO) more, multiple illuminators and single receiver (MISO), MIMO (MIMO) communication system, a kind of channel estimation methods that provides for clearer this embodiment of explanation, now the method is elaborated as example and in conjunction with Figure of description take a typical multiple-carrier multiple-antenna system, as shown in Figure 1, the method specifically can comprise:
At transmitting terminal, insert pilot tone, all the other available subcarrier position data insertings in the available subcarrier pilot frequency locations, the zero setting of virtual carrier position, through behind the inverse fourier transform, add Cyclic Prefix and form the transmission frame, through sending by transmitting antenna after filtering and the up-conversion.At receiving terminal, the frequency domain that at first extracts the corresponding pilot frequency locations of every transmitting antenna receives signal, and every transmitting antenna is carried out respectively preliminary channel estimation in frequency domain.
Further, the antenna configuration of supposing the system is 4 transmitting antennas and 4 reception antennas, i.e. N
T=4, N
R=4.Adopt the OFDM modulation system that whole 10MHz bandwidth is divided into 1024 subcarriers, wherein 600 subcarriers are useful subcarrier, and all the other 424 subcarriers are virtual carrier.
At transmitting terminal, at first insert known pilot take pilot interval as 6 at frequency domain, wherein, different transmit antennas takies different carrier waves, all the other useful sub-carrier positions data insertings, the zero padding of virtual carrier position; Then carry out inverse fourier transform, obtain time-domain signal; Form frame after adding at last Cyclic Prefix, after the filtering up-conversion, send by transmitting antenna.At receiving terminal, all reception antennas adopt identical channel estimation methods.For every reception antenna, at first carry out Fourier transform and obtain frequency-region signal, extract respectively pilot signal corresponding to different transmitting antennas.For the pilot tone of every transmitting antenna, frequency pilot sign and the local pilot frequency sequence that extracts be divided by obtains initial frequency domain estimation.
After carrying out channel estimation in frequency domain, respectively the channel frequency domain response of every transmitting antenna pilot frequency locations is carried out interpolation, obtain respectively the frequency domain response of the every whole available subcarriers of transmitting antenna
Be specially: for the pilot tone of every transmitting antenna, be divided by by the frequency pilot sign that extracts and local pilot frequency sequence obtain initial frequency domain estimation after, carry out the channel estimation value that the frequency domain linear interpolation obtains whole available carrier wave
According to the frequency domain response in the step 11, carry out time domain noise reduction and process, obtain the time domain impulse response of every transmitting antenna respective channels, and carry out Fourier transform, obtain the frequency domain response estimation of every transmitting antenna respective channels
Be specially: with carrying out inverse fourier transform after the as a result virtual carrier part zero padding of the pilot tone in the step 11, obtain the time domain impulse response, keep the above impulse response of noise gate, after all the other position zero setting, carry out Fourier transform, the frequency domain response behind the noise that is inhibited
At last, the estimated value that obtains according to frequency domain initial channel estimating and interpolation of the virtual carrier of selected threshold m part
The frequency domain response estimation value behind the Fourier transform is carried out in replacement
Obtain final estimated value
Be specially: choose near virtual carrier position m
Estimated value is replaced correspondence position
Estimated value obtain final channel estimation results
Wherein, the method for definite threshold m can be chosen the maximum of m, so that the channel estimation errors of frequency domain and interpolation is less than the channel estimation errors of estimating based on time domain.
In addition, for multiaerial system, transmitting terminal can be by the corresponding different frequency domain carrier position pilot tones of different transmitting antennas, receiving terminal can be according to different pilots insertions position, extract the channel information of different transmitting antennas, the recycling said method obtains the channel information between whole transmitting antenna reception antennas.
After obtaining channel estimation results, can be by the effect of analogue system authenticated channel estimation.It is 2.3GHz that the system of emulation adopts carrier frequency, bandwidth is 10MHz, sub-carrier number 1024, wherein the available carrier wave number is 600,1 direct current carrier wave, the pilot tone frequency domain is spaced apart 6, chooses EVA(Extended Vehicular A model) channel parameter, the speed of a motor vehicle is 30km/h, and prefix length is greater than maximum multipath time delay.Simulation result shows, when signal to noise ratio (snr) was 20dB, the channel estimation methods mean square error (MSE) that this embodiment provides can reach 2 * 10
-3, and initial channel estimation MSE is 7 * 10
-3, simultaneously because virtual carrier exists, rise on the contrary 10 through MSE behind the inverse fourier transform inhibition noise
-2
Simulation result shows, the channel estimation methods that this embodiment provides chooses that frequency domain is estimated and time domain evaluated error least part makes up, and can effectively suppress the evaluated error at virtual carrier edge, the raising precision of channel estimation.
The specific embodiment of the present invention also provides a kind of channel estimating apparatus, as shown in Figure 2, specifically can comprise initial channel estimation unit 21, frequency domain interpolation unit 22, time domain noise reduction processing unit 23 and estimated result determining unit 24, initial channel estimation unit 21 is used for carrying out initial channel estimation in frequency domain according to pilot tone; Frequency domain interpolation unit 22 is used for carrying out frequency domain interpolation according to initial channel estimation in frequency domain result and estimates; Time domain noise reduction processing unit 23 is used for carrying out time domain noise reduction according to pilot tone to be processed; Estimated result determining unit 24 is used for choosing the poor result less than replacing based on the estimated result of time domain evaluated error after time domain noise reduction is processed of channel estimating that frequency domain and interpolation are satisfied in the virtual carrier position.
Further, in the initial channel estimation unit, corresponding initial channel estimation in frequency domain can adopt frequency domain least-squares estimation, frequency domain least mean-square error to estimate or the frequency domain maximal possibility estimation; In frequency domain interpolation unit, corresponding frequency domain interpolation can comprise first-order linear interpolation, second order interpolation or high-order interpolation; In the time domain noise reduction processing unit, corresponding time domain noise reduction is processed the method that can adopt time domain least-squares estimation, the estimation of time domain least mean-square error, time domain maximal possibility estimation or estimate based on Fourier transform.
In addition, corresponding estimated result determining unit comprises for the channel estimation errors on each subcarrier of more initial channel estimation in frequency domain and time domain noise reduction processing, and chooses the less result of virtual carrier edge sub-carrier channels evaluated error as final estimated result.
This embodiment is at first carried out initial channel estimation in frequency domain by initial channel estimation unit 21 according to pilot tone, then carrying out frequency domain interpolation by frequency domain interpolation unit 22 according to initial channel estimation in frequency domain result estimates, carry out time domain noise reduction by time domain noise reduction processing unit 23 according to pilot tone again and process, choose the poor result less than replacing based on the estimated result of time domain evaluated error after time domain noise reduction is processed of the channel estimating that satisfies frequency domain and interpolation in the virtual carrier position by estimated result determining unit 24 at last.
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 for the better embodiment of the present invention, but protection scope of the present invention is not limited to this, anyly is 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 (10)
1. a channel estimation methods is characterized in that, comprising:
Carry out initial channel estimation in frequency domain according to pilot tone;
Carrying out frequency domain interpolation according to described initial channel estimation in frequency domain result estimates;
Carrying out time domain noise reduction according to described pilot tone processes;
Choose the poor result less than replacing based on the estimated result of time domain evaluated error after time domain noise reduction is processed of the channel estimating that satisfies frequency domain and interpolation in the virtual carrier position.
2. method according to claim 1 is characterized in that, described initial channel estimation in frequency domain adopts frequency domain least-squares estimation, frequency domain least mean-square error to estimate or the frequency domain maximal possibility estimation.
3. method according to claim 1 is characterized in that, described frequency domain interpolation comprises first-order linear interpolation, second order interpolation or high-order interpolation.
4. method according to claim 1 is characterized in that, described time domain noise reduction is processed the method that adopts time domain least-squares estimation, the estimation of time domain least mean-square error, time domain maximal possibility estimation or estimate based on Fourier transform.
5. according to claim 1 to the described method of 4 any one, it is characterized in that, choose the poor result less than replacing after time domain noise reduction is processed based on the estimated result of time domain evaluated error of the channel estimating that satisfies frequency domain and interpolation in the virtual carrier position and comprise:
Channel estimation errors on each subcarrier that more initial channel estimation in frequency domain and time domain noise reduction are processed, and choose the less result of virtual carrier edge sub-carrier channels evaluated error as final estimated result.
6. a channel estimating apparatus is characterized in that, comprising:
The initial channel estimation unit is used for carrying out initial channel estimation in frequency domain according to pilot tone;
Frequency domain interpolation unit is used for carrying out frequency domain interpolation according to described initial channel estimation in frequency domain result and estimates;
The time domain noise reduction processing unit is used for carrying out time domain noise reduction according to described pilot tone and processes;
The estimated result determining unit is used for choosing the poor result less than replacing based on the estimated result of time domain evaluated error after time domain noise reduction is processed of channel estimating that frequency domain and interpolation are satisfied in the virtual carrier position.
7. device according to claim 6 is characterized in that, in the initial channel estimation unit, described initial channel estimation in frequency domain adopts frequency domain least-squares estimation, frequency domain least mean-square error to estimate or the frequency domain maximal possibility estimation.
8. device according to claim 6 is characterized in that, in frequency domain interpolation unit, described frequency domain interpolation comprises first-order linear interpolation, second order interpolation or high-order interpolation.
9. device according to claim 6, it is characterized in that, in the time domain noise reduction processing unit, described time domain noise reduction is processed the method that adopts time domain least-squares estimation, the estimation of time domain least mean-square error, time domain maximal possibility estimation or estimate based on Fourier transform.
10. according to claim 6 to the described device of 9 any one, it is characterized in that, described estimated result determining unit comprises for the channel estimation errors on each subcarrier of more initial channel estimation in frequency domain and time domain noise reduction processing, and chooses the less result of virtual carrier edge sub-carrier channels evaluated error as final estimated result.
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| CN102457456B (en) * | 2010-10-27 | 2015-06-17 | 普天信息技术研究院有限公司 | Channel balancing method and device for UE end |
| CN102006248A (en) * | 2010-11-26 | 2011-04-06 | 北京邮电大学 | Multi-carrier based channel estimation method and device as well as application thereof |
| CN102035770B (en) * | 2010-12-01 | 2013-06-12 | 南京航空航天大学 | Method for estimating channel by means of correlation |
| CN102571661B (en) * | 2010-12-22 | 2014-08-13 | 无锡物联网产业研究院 | Matrix simplifying method, de-noising method and de-noising device |
| CN102143099B (en) * | 2010-12-22 | 2013-10-02 | 无锡物联网产业研究院 | Channel estimation method and device |
| CN102571650B (en) * | 2011-12-20 | 2014-06-18 | 东南大学 | Self-adapting channel estimating method applied to 3GPP LTE system |
| CN102546490B (en) * | 2012-01-11 | 2015-01-28 | 中国科学院上海微系统与信息技术研究所 | Channel estimation method applied to wireless sensor network |
| CN103391266B (en) * | 2012-05-11 | 2016-12-14 | 电信科学技术研究院 | The acquisition methods of a kind of domain channel response and equipment |
| 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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| CN1791077A (en) * | 2005-12-29 | 2006-06-21 | 上海贝豪通讯电子有限公司 | Time-domain and frequency-domain combined channel estimating method |
| CN101083644A (en) * | 2006-06-01 | 2007-12-05 | 大唐移动通信设备有限公司 | Channel estimation method of OFDM system |
| WO2009043200A1 (en) * | 2007-09-30 | 2009-04-09 | Thomson Licensing | Interpolation method and apparatus using tracking filter in multi-carrier receiver |
| CN101267422A (en) * | 2008-03-10 | 2008-09-17 | 电子科技大学 | A frequency domain channel estimation method for OFDM multiplex system |
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