CN103379073A - Uplink noise estimation method - Google Patents

Uplink noise estimation method Download PDF

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CN103379073A
CN103379073A CN2012101207062A CN201210120706A CN103379073A CN 103379073 A CN103379073 A CN 103379073A CN 2012101207062 A CN2012101207062 A CN 2012101207062A CN 201210120706 A CN201210120706 A CN 201210120706A CN 103379073 A CN103379073 A CN 103379073A
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pilot
noise
uplink
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CN103379073B (en
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刘昊
冯绍鹏
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Potevio Institute of Technology Co Ltd
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Abstract

The invention provides an uplink noise estimation method. According to the method, communication channel response estimation of pilot frequency subcarriers of even sequence numbers on a time slot n and communication channel response estimation of pilot frequency subcarriers of odd sequence numbers on the time slot n in each group of pilot frequency subcarriers are firstly utilized, first order difference operation is respectively carried out on a frequency domain, then second order difference is carried out on the frequency domain by means of a first order difference result, and third order difference is carried out on a time domain based on a second order difference result at last. Through the adoption of the uplink noise estimation method, accuracy of uplink noise estimation can be guaranteed when selective fading of the frequency domain is relatively obvious.

Description

The upstream noise method of estimation
Technical field
The present invention relates to mobile communication technology, particularly relate to the method that a kind of upstream noise is estimated.
Background technology
Noise power estimation is the important component part of LTE system, and the balanced detection of receiving terminal, soft bit decoding, CQI calculate and be unable to do without noise power-value, and the accuracy of therefore estimating can directly have influence on the performance of whole system.
Comparatively common noise Estimation Algorithm has two kinds in the ofdm system: a kind of is to do noise at frequency domain to estimate, a kind of is to do noise in time domain to estimate.
Frequency domain noise Estimation Algorithm advantage realizes fairly simple, but needs the estimating channel information recovering signal, owing to be subject to the accuracy impact of channel estimating, noise estimation value is less than normal when causing low signal-to-noise ratio, and during high s/n ratio, noise estimation value is bigger than normal.
The noise in time domain algorithm for estimating is fourier transformed into time domain by domain channel response, estimates between the noise range on time domain, implements complicated.And the Fourier transform under the non-integral multiple sampling can cause the leakage of channel multi-path energy, comprises that not only noise also has the leakage of channel multi-path between the noise range, and both can't separate, thereby causes estimating noise inaccurate.
In order to overcome above-mentioned two kinds of existing the problems referred to above of common noise estimation method, a kind of method of Difference Calculation noise power is suggested.By repeatedly on the time-frequency domain pilot sub-carrier difference remove the residue of channel response, remaining noise information only, and then the noise power of estimating is also more accurate.Existing differential noise algorithm for estimating is chosen adjacent continuous subcarrier composition group and is done first-order difference, then adjacent pilot tone group first-order difference value continues to do second differnce, because the relative independence in front and back between the pilot tone group, when the decline of frequency domain selectivity is more obvious, second differnce result can leave over channel response information, and it is inaccurate to cause noise to estimate; Existing difference method also is not suitable for the situation of up MU-MIMO in addition, because after receiving signal and a certain subscriber's local pilot signal conjugate multiplication, can obtain two users' channel response stack, and another user is not mated owing to sending pilot tone and local pilot tone above-mentioned, this moment, this subscriber channel no longer included correlation at frequency domain, carry out the channel response value that difference must be eliminated this user this moment, causes the noise misjudgment.
This shows that the method existence of above-mentioned Difference Calculation noise power noise when the decline of frequency domain selectivity is more obvious is estimated inaccurate problem, and also is not suitable for the situation of up MU-MIMO.
Summary of the invention
In view of this, main purpose of the present invention is to provide a kind of method of upstream noise estimation, and the method can be guaranteed the accuracy that noise is estimated.
In order to achieve the above object, the technical scheme of the present invention's proposition is:
The method that a kind of upstream noise is estimated, the method may further comprise the steps:
A, in advance the pilot sub-carrier of system divided into groups, wherein, every group of pilot sub-carrier comprises the default m continuous pilot sub-carrier, the even number of described m for being divided exactly by the pilot sub-carrier sum of system;
B, for every group of described pilot sub-carrier, calculate on each time slot n of current sub-frame of uplink, the channel response on each the pilot sub-carrier i in this group pilot sub-carrier is estimated
Figure BDA0000156106980000021
And described on this time slot n of the pilot sub-carrier that utilizes odd indexed in this group pilot sub-carrier
Figure BDA0000156106980000022
Carry out the first-order difference operation on the frequency domain, obtain as a result Δ of first-order difference N, strange, described on this time slot n of the pilot sub-carrier that utilizes even number sequence number in this group pilot sub-carrier Carry out the first-order difference operation on the frequency domain, obtain as a result Δ of first-order difference N, idol
C, for every group of described pilot sub-carrier, utilize the respectively described Δ on two time slots of current sub-frame of uplink of this group pilot sub-carrier N, strangeWith described Δ N, idol, carry out the second differnce operation at frequency domain, and utilize described second differnce result to carry out the third order difference operation in time domain, obtain as a result Δ of third order difference, calculate σ 2=| Δ | 2/ 24, with described σ 2Be defined as this and organize noise power σ corresponding to described pilot sub-carrier 2
D, calculate the described noise power σ of all described pilot subcarrier sets 2Mean value, with the noise power estimation value P of this mean value as current sub-frame of uplink Noise_est
In sum, the method of estimation of the upstream noise that the present invention proposes forms strange pilot tone group and even pilot tone group by the pilot sub-carrier that extracts respectively the odd even position, and then carries out single order and second differnce operation based on this at frequency-domain and time-domain, so, but the precision that the Effective Raise noise is estimated.
Description of drawings
Fig. 1 is the schematic flow sheet of the embodiment of the invention one;
Fig. 2 is a simulation result figure of the present invention.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with the accompanying drawings and the specific embodiments.
Core concept of the present invention is: utilize the Difference Calculation method to realize the present invention, with existing Difference Calculation method difference be: when the present invention carries out Difference Calculation at frequency domain, parity according to the pilot sub-carrier sequence number is divided into groups, be about to the pilot sub-carrier of odd number as one group, the pilot sub-carrier of even number as one group, and then is done single order and second differnce at frequency domain respectively in odd number group and even number set.Like this, because there are neighbouring relations in the pilot sub-carrier of odd number group and the pilot sub-carrier of even number set, therefore the coverage of these two carrier wave set is also near identical, like this, just can avoid the noise estimation value problem bigger than normal that produces clearly the time in the frequency selective fading of channel, thereby can guarantee the accuracy that noise is estimated.
Fig. 1 is the schematic flow sheet of the upstream noise method of estimation of the embodiment of the invention one, and as shown in Figure 1, the method may further comprise the steps:
Step 101, in advance the pilot sub-carrier of system divided into groups, wherein, every group of pilot sub-carrier comprises the default m continuous pilot sub-carrier.
The even number of described m for being divided exactly by the pilot sub-carrier sum of system specifically can be arranged according to actual needs by those skilled in the art, and preferably, described m can be set to 6.
Step 102, for every group of described pilot sub-carrier, calculate on each time slot n of current sub-frame of uplink, the channel response on each the pilot sub-carrier i in this group pilot sub-carrier is estimated
Figure BDA0000156106980000031
And described on this time slot n of the pilot sub-carrier that utilizes odd indexed in this group pilot sub-carrier
Figure BDA0000156106980000032
Carry out the first-order difference operation on the frequency domain, obtain as a result Δ of first-order difference N, strange, described on this time slot n of the pilot sub-carrier that utilizes even number sequence number in this group pilot sub-carrier Carry out the first-order difference operation on the frequency domain, obtain as a result Δ of first-order difference N, idol
In this step, in order to reduce frequency domain selectivity decline noise is estimated the impact of accuracy, described on time slot n of the pilot sub-carrier that utilizes even number sequence number in each group pilot sub-carrier
Figure BDA0000156106980000042
With described on time slot n of the pilot sub-carrier of odd indexed
Figure BDA0000156106980000043
Carry out the first-order difference operation at frequency domain respectively.Here, corresponding described of the pilot sub-carrier by calculating respectively the even number sequence number
Figure BDA0000156106980000044
With corresponding described of the pilot sub-carrier of odd indexed
Figure BDA0000156106980000045
Can guarantee to carry out two of first-order difference as a result Δs N, strangeAnd Δ N, idolThe carrier wave coverage near identical, like this, when in subsequent step, utilizing the first-order difference result on frequency domain, to do second differnce again, just can guarantee when the decline of frequency domain selectivity is more obvious, no longer leave over channel response information among the second differnce result, and then can guarantee the accuracy that noise is estimated.
Better, the channel response that can adopt least square method (LS criterion) to obtain on each pilot sub-carrier i is estimated
Figure BDA0000156106980000046
Particularly, when the number of users that takies a Resource Block in the system when being single, calculate described
Figure BDA0000156106980000047
Can adopt existing method to realize, not repeat them here.
In addition, the present invention also is applicable in the MU-MIMO system.Particularly, when the up number of users that takies same resource block on the same sub-frame of uplink is two, can according to
Figure BDA0000156106980000048
Or
Figure BDA0000156106980000049
Obtain the described of pilot sub-carrier
Figure BDA00001561069800000410
Wherein said
Figure BDA00001561069800000411
For the reception signal on n time-multiplexed pilot subcarrier i of current sub-frame of uplink, described
Figure BDA00001561069800000412
For the pilot signal of first user on pilot sub-carrier i on n time slot of current sub-frame of uplink, described
Figure BDA00001561069800000413
Be the pilot signal of second user on pilot sub-carrier i on n time slot of current sub-frame of uplink, i is pilot sub-carrier number, and n is timeslot number.
Need to prove that when described system is the MU-MIMO system, and the up number of users that takies same resource block on the same sub-frame of uplink is when being two, described two up users' pilot tone cyclic shift interval n CsDifference need to be set to 6.
Preferably, when described m=6, can according to
Figure BDA00001561069800000414
Obtain described Δ N, strangeAccording to
Figure BDA00001561069800000415
Obtain described Δ N, idol
Step 103, for every group of described pilot sub-carrier, utilize the respectively described Δ on two time slots of current sub-frame of uplink of this group pilot sub-carrier N, strangeWith described Δ N, idol, carry out the second differnce operation at frequency domain, and utilize described second differnce result to carry out the third order difference operation in time domain, obtain as a result Δ of third order difference, calculate σ 2=| Δ | 2/ 24, with described σ 2Be defined as this and organize noise power σ corresponding to described pilot sub-carrier 2
In this step, the field selectivity decline is estimated the impact of accuracy to noise in order to reduce, and utilizes the respectively Δ on two time slots at current sub-frame of uplink of one group of pilot sub-carrier in time domain N, strangeAnd Δ N, idol, carry out the third order difference operation on the time domain.
Preferably, can be according to Δ=(Δ 1, strange-Δ 1, idol)-(Δ 2, strange-Δ 2, idol) obtain described Δ, wherein, (Δ 1, strange-Δ 1, idol) and (Δ 2, strange-Δ 2, idol) two time slots being respectively at current sub-frame of uplink are the second differnce operation that time slot 1 and time slot 2 are done.
Step 104, calculate the described noise power σ of all described pilot subcarrier sets 2Mean value, with the noise power estimation value P of this mean value as current sub-frame of uplink Noise_est
Particularly, in this step according to P Noise_est=σ 2/ T obtains described P Noise_est, wherein, described T is the pilot subcarrier sets number that obtains after the described grouping.
Further, for the shake of noise decrease estimated value, can between subframe, carry out smoothing processing after the step 104, particularly, can adopt following step to realize:
According to P Noise_new=λ * P Noise_pre+ (1-λ) P Noise_est, to described P Noise_estCarry out smoothing processing, obtain the noise power P after the smoothing processing Noise_new
Wherein, P Noise_preNoise power after the smoothing processing that obtains for a upper subframe, λ is default level and smooth weight, 0＜λ＜1, those skilled in the art can arrange suitable value according to actual needs particularly.
Simulation result figure (referring to Fig. 2) below by above-described embodiment further specifies technique effect of the present invention.
Simulated conditions: ETU channel UE single-shot, antenna (dual polarization), 20M bandwidth, 5 Resource Block of CU (RB) are received in base station 8.The noise power theoretical value is normalized to 1.
Simulation result from Fig. 2 can find out that noise estimated result of the present invention is basicly stable under above-mentioned simulated conditions equals 1 place in theoretical value, as seen, and the noise accuracy of estimation that the present invention can obtain highlyer.
In sum, more than be preferred embodiment of the present invention only, be not for limiting protection scope of the present invention.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. the method estimated of a upstream noise is characterized in that the method may further comprise the steps:
A, in advance the pilot sub-carrier of system divided into groups, wherein, every group of pilot sub-carrier comprises the default m continuous pilot sub-carrier, the even number of described m for being divided exactly by the pilot sub-carrier sum of system;
B, for every group of described pilot sub-carrier, calculate on each time slot n of current sub-frame of uplink, the channel response on each the pilot sub-carrier i in this group pilot sub-carrier is estimated And described on this time slot n of the pilot sub-carrier that utilizes odd indexed in this group pilot sub-carrier
Figure FDA0000156106970000012
Carry out the first-order difference operation on the frequency domain, obtain as a result Δ of first-order difference N, strange, described on this time slot n of the pilot sub-carrier that utilizes even number sequence number in this group pilot sub-carrier
Figure FDA0000156106970000013
Carry out the first-order difference operation on the frequency domain, obtain as a result Δ of first-order difference N, idol
C, for every group of described pilot sub-carrier, utilize the respectively described Δ on two time slots of current sub-frame of uplink of this group pilot sub-carrier N, strangeWith described Δ N, idol, carry out the second differnce operation at frequency domain, and utilize described second differnce result to carry out the third order difference operation in time domain, obtain as a result Δ of third order difference, calculate σ 2=| Δ | 2/ 24, with described σ 2Be defined as this and organize noise power σ corresponding to described pilot sub-carrier 2
D, calculate the described noise power σ of all described pilot subcarrier sets 2Mean value, with the noise power estimation value P of this mean value as current sub-frame of uplink Noise_est
2. method according to claim 1 is characterized in that, further comprises after the described steps d:
According to P Noise_new=λ * P Noise_pre+ (1-λ) P Noise_est, to described P Noise_estCarry out smoothing processing, obtain the noise power P after the smoothing processing Noise_net, wherein, P Noise_preNoise power after the smoothing processing that obtains for a upper subframe, λ is default level and smooth weight, 0＜λ＜1.
3. method according to claim 1 is characterized in that, described m=6.
4. method according to claim 3 is characterized in that, according to
Figure FDA0000156106970000014
Obtain described Δ N, strange
5. method according to claim 3 is characterized in that, according to
Figure FDA0000156106970000015
Obtain described Δ N, idol
6. method according to claim 1 is characterized in that, according to Δ=(Δ 1, strange-Δ 1, idol)-(Δ 2, strange-Δ 2, idol) obtain described Δ.
7. method according to claim 1 is characterized in that, it is described to adopt least square method to calculate among the described step b
Figure FDA0000156106970000021
8. method according to claim 7 is characterized in that, when described system is the MU-MIMO system, and the up number of users that takies same resource block on the same sub-frame of uplink is when being two, described two up users' pilot tone cyclic shift interval n CsDifference be 6.
9. method according to claim 8 is characterized in that, when described system is the MU-MIMO system, and the up number of users that takies same resource block on the same sub-frame of uplink is when being two, according to
Figure FDA0000156106970000022
Or
Figure FDA0000156106970000023
Obtain pilot sub-carrier described of described odd indexed
Figure FDA0000156106970000024
Wherein said
Figure FDA0000156106970000025
For the reception signal on n time-multiplexed pilot subcarrier i of current sub-frame of uplink, described
Figure FDA0000156106970000026
For the pilot signal of first user on pilot sub-carrier i on n time slot of current sub-frame of uplink, described
Figure FDA0000156106970000027
Pilot signal for second user on pilot sub-carrier i on n time slot of current sub-frame of uplink.
10. method according to claim 8 is characterized in that, when described system is the MU-MIMO system, and the up number of users that takies same resource block on the same sub-frame of uplink is when being two, according to
Figure FDA0000156106970000028
Or
Figure FDA0000156106970000029
Obtain pilot sub-carrier described of described odd indexed
Figure FDA00001561069700000210
Wherein said
Figure FDA00001561069700000211
For the reception signal on n time-multiplexed pilot subcarrier i of current sub-frame of uplink, described
Figure FDA00001561069700000212
For the pilot signal of first user on pilot sub-carrier i on n time slot of current sub-frame of uplink, described Pilot signal for second user on pilot sub-carrier i on n time slot of current sub-frame of uplink.
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Cited By (3)

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CN105024955A (en) * 2015-06-10 2015-11-04 北京北方烽火科技有限公司 A noise power estimation method and device
CN107347194A (en) * 2016-05-04 2017-11-14 大唐移动通信设备有限公司 A kind of up bottom is made an uproar processing method and system
CN114337868A (en) * 2021-12-28 2022-04-12 北京奕斯伟计算技术有限公司 Channel parameter estimation method, device, electronic equipment and readable storage medium

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CN102025426A (en) * 2009-09-17 2011-04-20 中兴通讯股份有限公司 Method and device for estimating carrier to interference plus noise ratio in orthogonal frequency division multiplexing system

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Publication number Priority date Publication date Assignee Title
US20040141457A1 (en) * 2003-01-18 2004-07-22 Bo-Seok Seo Method of determining training signal in OFDM, and apparatus and method for receiving OFDM signal using the training signal
CN1578290A (en) * 2003-07-08 2005-02-09 三星电子株式会社 System and method for channel estimation in an OFDM mobile communication system
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CN105024955A (en) * 2015-06-10 2015-11-04 北京北方烽火科技有限公司 A noise power estimation method and device
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CN107347194A (en) * 2016-05-04 2017-11-14 大唐移动通信设备有限公司 A kind of up bottom is made an uproar processing method and system
CN107347194B (en) * 2016-05-04 2020-05-08 大唐移动通信设备有限公司 Uplink background noise processing method and system
CN114337868A (en) * 2021-12-28 2022-04-12 北京奕斯伟计算技术有限公司 Channel parameter estimation method, device, electronic equipment and readable storage medium

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