CN101945070A - Method and device for measuring noise - Google Patents

Abstract

The invention discloses a method and a device for measuring noise, and an MIMO-OFDM system terminal receiving device. The method comprises the following steps of: measuring the noise for the first time according to frequency domain data after fast Fourier transform (FFT); estimating a channel by using the result of measuring the noise for the first time; and measuring the noise for the second time according to the frequency domain data and the channel estimation result, wherein the measured result is used for subsequent processing. The method and the device can improve the accuracy of noise measurement results and further improve the detection performance and system throughput.

Description

A kind of method of noise testing and device

Technical field

The present invention relates to communication technical field, relate in particular to a kind of method, device and MIMO-OFDM system terminal receiving system of noise testing.

Background technology

Multi-input multi-output-orthogonal frequency division multiplexing (MIMO-OFDM, Multiple Input MultipleOutput-Orthogonal Frequency Division Multiplexing) system adopts a kind of communication system of MIMO technology and OFDM technology simultaneously, it combines the advantage of MIMO technology and OFDM technology, becomes the main flow trend of future mobile communications.

As shown in Figure 1, rough schematic view for existing MIMO-OFDM system terminal base band receiving processing module, comprise: fast Fourier transform (FFT, Fast Fourier Transform) module, noise measurement module, channel estimation module, MIMO detection module, channel decoding module and feedback module etc.Wherein, noise measurement module is measured noise variance, and the channel estimation module that offers the back is finished channel estimating at frequency domain, channel estimating method Wiener filtering method for example commonly used at present, and this method need use noise power as parameter.Simultaneously, the measurement result of noise measurement module also offers the MIMO detection module, MIMO detection method commonly used at present, i.e. Xian Xing least mean-square error (MMSE, Minimum MeanSquare Error) detection method, also need noise power to import, and the accuracy of noise power will influence the detection performance as parameter.In addition, the measurement result of noise measurement module also offers the decoded operation that the channel decoding module is finished chnnel coding, usually need utilize signal to noise ratio (SNR owing to enter the soft bit of this channel decoding module, Signal to Noise Ratio) information is weighted, need noise variance information equally, and noise variance will influence the performance of channel decoding.In addition, if employing link adaptation techniques, terminal (UE then, User Equipment) feedback channel quality indication information such as (CQI:Channel Quality Indicator) also relates to the calculating of SNR, thereby need noise variance information equally, and the accuracy of noise variance will influence link throughput.In a word, for the MIMO-OFDM system, noise testing is very important.

Estimating noise method commonly used is to come the estimating noise variance with the difference between reference (RS, the Reference Signal) position that (or on time domain) is adjacent on the frequency domain in the ofdm system at present.

Utilize the method for adjacent R S on the frequency domain direction, promptly method one can be expressed as

Wherein E{} represents to ask desired operation.The mean value of estimating with all reference signals in the subframe replaces asking the expectation computing to get

${\widehat{\mathrm{\σ}}}^2=\frac{1}{2L_{\mathrm{RS}}(N_{\mathrm{RS}}-1)}\underset{l^{\′}=0}{\overset{L_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\underset{k^{\′}=0}{\overset{N_{\mathrm{RS}}-2}{\mathrm{\Σ}}}\left|\right|\frac{{\tilde{r}}_{k^{\′},l^{\′}}}{x_{k^{\′},l^{\′}}}{-\frac{{\tilde{r}}_{k^{\′}+1,l^{\′}}}{x_{k^{\′}+1,l^{\′}}}\left|\right|}^2$

L wherein _RSRepresent that a subframe includes the OFDM symbolic number of RS, N _RSBe illustrated in the sub-carrier number that comprises RS in the OFDM symbol.

Utilize the method and the said method one of the difference estimation noise variance at adjacent reference signal place on the time domain similar, can be expressed as

${\widehat{\mathrm{\σ}}}^2=\frac{1}{2N_{\mathrm{RS}}(L_{\mathrm{RS}}/2)}\underset{l^{\′}=0}{\overset{L_{\mathrm{RS}}/2-1}{\mathrm{\Σ}}}\underset{k^{\′}=0}{\overset{N_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\left|\right|\frac{{\tilde{r}}_{k^{\′},l^{\′}+2}}{x_{k^{\′},l^{\′}+2}}{-\frac{{\tilde{r}}_{k^{\′},l^{\′}}}{x_{k^{\′},l^{\′}}}\left|\right|}^2$

As seen, all be to utilize the frequency domain data after the FFT conversion to measure for noise power, existing method can be provided when the channel estimating.Yet there is following shortcoming in said method:

For method one because the channel impulse response at adjacent reference signal place is identical on the hypothesis frequency domain, and for the system that adopts discrete RS to distribute since on the frequency domain adjacent reference signal to differ frequency range big slightly, for some channel, the error of this hypothesis is bigger.For example, for third generation collaborative project (3GPP, 3 ^RdGeneration Partnership Project) the expansion typical urban channel of stipulating in the standard (ETU), above-mentioned hypothesis is untenable.Have this moment

E{|| Δ h wherein _{K '}|| ²The error of adjacent reference signal place channel difference noise on the expression frequency domain, E{||n|| ²The expression noise actual variance, the correlation of channel on frequency domain is more little, then E{|| Δ h _{K '}|| ²Xiang Huiyue is big, just represents that also error can be big more.And along with Doppler expands increasing, inter-carrier interference also becomes greatly, can make that error further strengthens.

For method two, because the channel impulse response at adjacent reference signal place is identical on the hypothesis time domain, along with the increase of moving velocity of terminal, the correlation at adjacent reference signal place is more and more littler on the time domain,

Item can be increasing, and promptly the error of Noise Variance Estimation can be increasing.

In realizing process of the present invention, the inventor is through discovering: existing noise measuring method all is to utilize FFT conversion frequency domain data afterwards to carry out, and its measured deviation under some channel conditions is bigger.And the noise variance deviation is bigger to MIMO detection performance impact more greatly, even can cause the detection mis-behave; Equally, the noise variance deviation more also will influence modules such as channel decoding and feedback, finally influence systematic function.As seen use existing noise measuring method can not guarantee under various channel conditions, to obtain more excellent detection performance.

Summary of the invention

The embodiment of the invention provides a kind of method, device and MIMO-OFDM system terminal receiving system of noise testing, can improve noise testing result's accuracy, and then improves and detect performance and throughput of system.

The embodiment of the invention provides following technical scheme:

A kind of method of noise testing comprises:

Carry out the noise testing first time according to the frequency domain data after the fast Fourier FFT conversion;

Utilize the result of the described noise testing first time to carry out channel estimating;

Carry out the noise testing second time according to described frequency domain data and channel estimation results, measurement result is for subsequent treatment.

A kind of device of noise testing comprises:

First noise measurement module is used for carrying out the noise testing first time according to the frequency domain data after the FFT conversion;

Second noise measurement module is used for according to the frequency domain data after the FFT conversion, and the result who utilizes the measurement result of described first noise measurement module to carry out channel estimating carries out noise testing second time, measurement result confession subsequent treatment.

A kind of MIMO-OFDM system terminal receiving system comprises:

First noise measurement module is used for carrying out the noise testing first time according to the frequency domain data after the FFT conversion;

Channel estimation module is used to utilize the measurement result of described first noise measurement module to carry out channel estimating;

Second noise measurement module is used for according to the frequency domain data after the FFT conversion, and the estimated result of described channel estimation module carries out the noise testing second time;

The MIMO detection module is used to utilize the measurement result of described second noise measurement module to detect.

The method of the noise testing that the embodiment of the invention provides, device and MIMO-OFDM system terminal receiving system, be applied in the not very sensitive channel estimating of the error of Noise Estimation by having noise measurement that noise measuring method obtains now, the channel estimation results that obtains is used for noise testing again, on existing noise measuring method, carry out a noise testing so again, make measurement result more accurate, and can guarantee under various channel conditions, to obtain more excellent performance.And noise testing result is accurately offered in the MIMO detection and feedback calculation of back, can improve and detect performance and throughput of system.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the rough schematic view of existing MIMO-OFDM system terminal base band receiving processing module;

Fig. 2 is the method flow diagram of the noise testing that provides of the embodiment of the invention one;

Fig. 3 is the schematic diagram that RS distributes in the LTE system;

Fig. 4 is based on the position view after RS shown in Figure 3 rearranges;

Fig. 5 is based on the schematic diagram after RS shown in Figure 4 renumbers;

Fig. 6 is the apparatus structure schematic diagram of the noise testing that provides of the embodiment of the invention two;

Fig. 7 is the MIMO-OFDM system terminal receiving system structural representation that the embodiment of the invention three provides.

Embodiment

The embodiment of the invention provides a kind of noise measuring method, device and MIMO-OFDM system terminal receiving system in the MIMO-OFDM system of being applicable to of superior performance, can improve noise testing result's accuracy, and then improves and detect performance and throughput of system.Because Long Term Evolution project (LTE, what Long TimeEvolution) system adopted is exactly the MIMO-OFDM system, for for simplicity, below illustrates all be example with LTE, but technical scheme provided by the present invention is applicable to all MIMO-OFDM systems, is not limited to the LTE system.For making purpose of the present invention, technical scheme and advantage clearer, the embodiment that develops simultaneously with reference to the accompanying drawings, the present invention is described in more detail.

The inventor analyzes the influence of all multimodes in back the measurement result of noise measurement module in the existing MIMO-OFDM system terminal receiving system in the above-mentioned background technology, the inventor further finds through research, the channel estimation methods of Wiener filtering is not very sensitive to the error of Noise Estimation, that is to say that it is not very big using present noise measuring method that performance for estimating channel is influenced, therefore, can receive in the processing at the MIMO-OFDM system terminal and carry out twice noise testing, noise testing for the first time can be used existing noise measuring method, its result offers channel estimation module and uses, and noise measuring method provided by the invention is used in noise testing for the second time, and the module that its result offers after the channel estimating is used.

As shown in Figure 2, the method flow diagram of the noise testing that provides for the embodiment of the invention one.Described method comprises:

Step 201, carry out the noise testing first time according to the frequency domain data after the FFT conversion;

Particularly, in the LTE system, carry out channel estimating, all inserted a certain amount of reference signal RS in each subframe for the ease of terminal.The corresponding OFDM symbol of each RS and a subcarrier.Concerning each sub-district, reference signal is the known definite signal of UE, and UE can go out the corresponding channel response in RS place according to the RS place data estimation that receives.Because time and bandwidth that each RS takies are all very little, what can think each RS experience all is smooth channel response; Simultaneously, because the adjacent interval of RS on time and frequency is all smaller,, can think that the channel response at adjacent RS place is basic identical much smaller than coherence bandwidth.Therefore after the received signal at RS place being calibrated, the difference between adjacent RS place calibrating signal has just embodied the difference of noise.Independently incoherent characteristics just can the estimating noise variance to utilize different RS place noise.The received signal that present disclosed simple Noise Variance Estimation method also all is based on the RS place is carried out.Below existing method is carried out simple declaration:

As shown in Figure 3, a schematic diagram for RS distribution in the LTE system, for simplicity, the time orientation length (during general cyclic prefix (CP)) of a subframe of only having drawn among Fig. 3, frequency domain direction 12 subcarriers that only drawn, and only represented RS distribution situation on the transmitting antenna port.Mark part is represented the position at reference signal place among Fig. 3, in the actual conditions different cell reference signals is had different side-play amounts on frequency domain, different transmitting antenna ports is had different distributions, but the relative position between each reference signal substantially to Fig. 3 in similar, what all adopt is this discrete reference signal location mode.

If r _{K, l}Be the received signal at k subcarrier place on l the OFDM symbol, 0≤k＜N wherein _Sc, 0≤l＜N _Symb, N _ScBe downlink sub-carrier sum, N _SymbRepresent the OFDM symbolic number that comprises in the subframe, N during common CP _Symb=14, N during extended pattern CP _Symb=12.Because follow-up received signal of being concerned about the reference signal place, for simplicity, the signal of the position of all non-reference signals removed put aside, after obtaining the reference signal position and rearranging as shown in Figure 4, again to after being numbered of reference signal position as shown in Figure 5, wherein Position relation in original running time-frequency resource can be clear that by Fig. 3,4,5.

Because the transmission signal of reference signal position is known to terminal, is assumed to be x _{K ', l '}, and in the LTE system || x _{K ', l '}||=1, suppose that the frequency domain channel impulse response of each reference signal position is expressed as h _{K ', l '}, then have following relational expression to set up

${\tilde{r}}_{k^{\′},l^{\′}}=h_{k^{\′},l^{\′}}{x}_{k^{\′},l^{\′}}+n_{k^{\′},l^{\′}},$

N wherein _{K ', l '}The expression noise component(s) is estimated n _{K ', l '}Variance adopt dual mode of the prior art here, specify as follows:

Utilize the method for adjacent R S on the frequency domain direction to be expressed as

${\widehat{\mathrm{\σ}}}^2=\frac{1}{2}E\left\{\right|\left|\frac{{\tilde{r}}_{k^{\′},l^{\′}}}{x_{k^{\′},l^{\′}}}{-\frac{{\tilde{r}}_{k^{\′}+1,l^{\′}}}{x_{k^{\′}+1,l^{\′}}}\left|\right|}^2\right\}$

Wherein E{} represents to ask desired operation.

The mean value of estimating with all reference signals in the subframe replaces asking the expectation computing to get

${\widehat{\mathrm{\σ}}}^2=\frac{1}{2L_{\mathrm{RS}}(N_{\mathrm{RS}}-1)}\underset{l^{\′}=0}{\overset{L_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\underset{k^{\′}=0}{\overset{N_{\mathrm{RS}}-2}{\mathrm{\Σ}}}\left|\right|\frac{{\tilde{r}}_{k^{\′},l^{\′}}}{x_{k^{\′},l^{\′}}}{-\frac{{\tilde{r}}_{k^{\′}+1,l^{\′}}}{x_{k^{\′}+1,l^{\′}}}\left|\right|}^2---\left(1\right)$

L wherein _RSRepresent that a subframe includes the OFDM symbolic number of RS, N _RSBe illustrated in the sub-carrier number that comprises RS in the OFDM symbol.Adjacent R S is shown in arrow among Fig. 31 on the frequency domain direction, and adjacent R S is shown in arrow among Fig. 32 on the time domain direction.

Utilize the method and the said method of the difference estimation noise variance at adjacent reference signal place on the time domain similar, can be expressed as

${\widehat{\mathrm{\σ}}}^2=\frac{1}{2N_{\mathrm{RS}}(L_{\mathrm{RS}}/2)}\underset{l^{\′}=0}{\overset{L_{\mathrm{RS}}/2-1}{\mathrm{\Σ}}}\underset{k^{\′}=0}{\overset{N_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\left|\right|\frac{{\tilde{r}}_{k^{\′},l^{\′}+2}}{x_{k^{\′},l^{\′}+2}}{-\frac{{\tilde{r}}_{k^{\′},l^{\′}}}{x_{k^{\′},l^{\′}}}\left|\right|}^2---\left(2\right)$

Owing to adopted discrete reference signal to distribute among the LTE, adjacent reference signal l ' index value differs 2 on the middle time domain of formula (2), specifically can be referring to shown in the arrow among Fig. 32.

Step 202, utilize the result of the described noise testing first time to carry out channel estimating;

Here can adopt existing MMSE channel estimation methods to carry out channel estimating.

Step 203, carry out the noise testing second time according to the result of described frequency domain data and channel estimating, measurement result is for subsequent treatment.

Particularly, adopt noise measuring method provided by the invention herein, still contrast Fig. 5, suppose that the frequency domain channel estimated result that RS position (k ', l ') is located is

Noise estimation method then provided by the invention can be expressed as follows:

${\widehat{\mathrm{\σ}}}^2=E\left\{\right|\left|{{\tilde{r}}_{k^{\′},l^{\′}}-x_{k^{\′},l^{\′}}\·{\hat{h}}_{k^{\′}.l^{\′}}\left|\right|}^2\right\}=\frac{1}{N_{\mathrm{RS}}{L}_{\mathrm{RS}}}\underset{l^{\′}}{\overset{L_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\underset{k^{\′}=0}{\overset{N_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\left|\right|{{\tilde{r}}_{k^{\′},l^{\′}}-x_{k^{\′},l^{\′}}\·{\hat{h}}_{k^{\′},l^{\′}}\left|\right|}^2---\left(3\right)$

Wherein E{} represents to ask desired operation, L _RSRepresent that a subframe includes the OFDM symbolic number of RS, N _RSBe illustrated in the sub-carrier number that comprises RS in the orthogonal frequency division multiplex OFDM symbol, The frequency domain channel estimated result of locating for RS position (k ', l '),

Be the received signal that RS position (k ', l ') locates, x _{K ', l '}The transmission signal of locating for RS position (k ', l ').

Owing to be mimo system, so the measured value on each transmitting antenna and the reception antenna can average, and above-mentioned formula (3) can further be expressed as follows

${\widehat{\mathrm{\σ}}}^2=\frac{1}{N_T{N}_R{N}_{\mathrm{RS}}{L}_{\mathrm{RS}}}\underset{j=0}{\overset{N_R-1}{\mathrm{\Σ}}}\underset{i=0}{\overset{N_T-1}{\mathrm{\Σ}}}\underset{l^{\′}}{\overset{L_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\underset{k^{\′}=0}{\overset{N_{\mathrm{RS}}-1}{\mathrm{\Σ}}}\left|\right|{\tilde{r}}_{k^{\′}{j}^{\′}}^{i,j}-x_{k^{\′}{j}^{\′}}^{i,j}\·{\hat{h}}_{k^{\′},j^{\′}}^{i,j}{\left|\right|}^2---\left(4\right)$

I wherein, j is respectively the index of transmitting antenna and reception antenna port, N _T, N _RRepresent number of transmit antennas and reception antenna number respectively.

Further, can utilize the result of the described noise testing second time to carry out MIMO and detect, channel decoding, and subsequent treatment such as feedback calculation.

Technical scheme is for a better understanding of the present invention set forth below by an application example is further concrete.

At first, the time domain data that receiver receives in the LTE system is through the frequency domain data after the FFT conversion, and supposing to handle with a subframe is unit, and then frequency domain reception data can be expressed as

R wherein _lThe vector that expression is made up of the data of an OFDM symbol, N _SymbBe the sum of OFDM symbol in the subframe, wherein

R wherein _{K, l}Represent the reception data on interior k the subcarrier of l OFDM symbol.

Secondly,,, carry out mark and numbering after the compact arrangement again, can be designated as from receiving the reception data that extracting data goes out reference signal according to the distribution of RS

Wherein

Interior all the RS places of OFDM symbol that represent the individual RS of carrying of l ' receive the vector that data are formed,

Wherein

The reception data of representing the interior individual RS of the k ' place of OFDM symbol of the individual RS of carrying of l '.

Then, utilize above-mentioned formula (1)

Perhaps formula (2)

Carry out the noise testing first time.

Adopt existing MMSE channel estimation methods to carry out channel estimating again, suppose that the channel estimation value at the RS place that obtains is

Wherein

The vector of representing the channel estimation value composition at all RS places in the OFDM symbol of the individual RS of carrying of l ', Wherein

The channel estimation value of representing the interior individual RS of the k ' place of OFDM symbol of the individual RS of carrying of l '.

At last, according to above-mentioned formula (4)

Carry out

Noise testing for the second time adopts the result of the Noise Estimation second time to carry out subsequent treatment, comprises MIMO detection, feedback calculation etc.

As shown in Figure 6, the apparatus structure schematic diagram of the noise testing that provides for the embodiment of the invention two.This device comprises: first noise measurement module 610, second noise measurement module 620; Wherein,

Described first noise measurement module 610 is used for carrying out the noise testing first time according to the frequency domain data after the FFT conversion; Particularly, described first noise measurement module 610 is utilized above-mentioned formula (1)

Perhaps formula (2) Carry out the noise testing first time.

Described second noise measurement module 620 is used for according to the frequency domain data after the FFT conversion, and the result who utilizes the measurement result of described first noise measurement module 610 to carry out channel estimating carries out noise testing second time, measurement result confession subsequent treatment.Particularly, described second noise measurement module, 620 formula (4)

Carry out the noise testing second time, obtain the second time Noise Estimation the result for subsequent treatment, for example MIMO detection, feedback calculation etc.

As shown in Figure 7, the MIMO-OFDM system terminal receiving system structural representation that provides for the embodiment of the invention three.Described device comprises: FFT module 710, first noise measurement module 720, channel estimation module 730, second noise measurement module 740, MIMO detection module 750, channel decoding module 760 and feedback module 770; Wherein:

This device carries out twice noise testing, and existing method is used in noise testing for the first time, and its result offers channel estimation module and uses, and noise testing algorithm provided by the invention is used in noise testing for the second time, and the module that its result offers after the channel estimating is used.Particularly, first noise measurement module 720 is according to carrying out the noise testing first time through the frequency domain data after 710 conversion of FFT module, the first noise testing result who obtains is offered channel estimation module 730, so that channel estimation module 730 utilizes the described first noise testing result and carries out channel estimating through the frequency domain data after 710 conversion of FFT module; Channel estimation results offers second noise measurement module 740 on the one hand, offers MIMO detection module 750 on the other hand.Second noise measurement module 740 is according to the frequency domain data after the FFT conversion, reach described channel estimation results and carry out the noise testing second time, the second noise testing result who obtains is offered MIMO detection module 750, channel decoding module 760 and feedback module 770 respectively.

By experiment as can be known, more near actual value, especially performance of the present invention is more outstanding under the condition of high s/n ratio than existing method for noise measuring method provided by the invention, approaches to use the performance of desirable noise power.

One of ordinary skill in the art will appreciate that and realize that all or part of step that the foregoing description method is carried is to instruct relevant hardware to finish by program, described program can be stored in a kind of computer-readable recording medium, this program comprises one of step or its combination of method embodiment when carrying out.

In addition, each functional unit in each embodiment of the present invention can be integrated in the processing module, also can be that the independent physics in each unit exists, and also can be integrated in the module two or more unit.Above-mentioned integrated module both can adopt the form of hardware to realize, also can adopt the form of software function module to realize.If described integrated module realizes with the form of software function module and during as independently production marketing or use, also can be stored in the computer read/write memory medium.

The above-mentioned storage medium of mentioning can be a read-only memory, disk or CD etc.

In sum, this paper provides a kind of method, device and MIMO-OFDM system terminal receiving system of noise testing, be applied in the not very sensitive channel estimating of the error of Noise Estimation by having noise measurement that noise measuring method obtains now, the channel estimation results that obtains is used for noise testing again, on existing noise measuring method, carry out a noise testing so again, make measurement result more accurate, and can guarantee under various channel conditions, to obtain more excellent performance.And noise testing result is accurately offered in the MIMO detection and feedback calculation of back, can improve and detect performance and throughput of system.

More than method, device and the MIMO-OFDM system terminal receiving system of noise testing provided by the present invention is described in detail, used specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand the solution of the present invention; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (10)

1. the method for a noise testing is characterized in that, comprising:

Carry out the noise testing first time according to the frequency domain data after the fast Fourier FFT conversion;

Utilize the result of the described noise testing first time to carry out channel estimating;

Carry out the noise testing second time according to described frequency domain data and channel estimation results, measurement result is for subsequent treatment.

2. the method for noise testing according to claim 1 is characterized in that, described measurement result comprises for subsequent treatment:

Utilize the result of the described noise testing second time to carry out multiple-input and multiple-output MIMO detection.

3. the method for noise testing according to claim 1 is characterized in that, described measurement result comprises for subsequent treatment:

Utilize the measurement result of described second noise measurement module to carry out the decoding processing of chnnel coding, and/or utilize the result of the described noise testing second time to carry out feedback calculation.

4. the method for noise testing according to claim 1 is characterized in that, the described noise testing second time is expressed as:

Wherein E{} represents to ask desired operation, L _RSRepresent that a subframe includes the OFDM symbolic number of RS, N _RSBe illustrated in the sub-carrier number that comprises RS in the orthogonal frequency division multiplex OFDM symbol,

The frequency domain channel estimated result of locating for RS position (k ', l '),

Be the received signal that RS position (k ', l ') locates, x _{K ', l '}The transmission signal of locating for RS position (k ', l ').

5. the method for noise testing according to claim 4 is characterized in that, the described noise testing second time further is expressed as:

I wherein, j is respectively the index of transmitting antenna and reception antenna port, N _T, N _RRepresent number of transmit antennas and reception antenna number respectively.

6. the device of a noise testing is characterized in that, comprising:

First noise measurement module is used for carrying out the noise testing first time according to the frequency domain data after the FFT conversion;

Second noise measurement module is used for according to the frequency domain data after the FFT conversion, and the result who utilizes the measurement result of described first noise measurement module to carry out channel estimating carries out noise testing second time, measurement result confession subsequent treatment.

7. the device of noise testing according to claim 6 is characterized in that, described second noise measurement module is carried out the noise testing second time by following expression formula:

Wherein E{} represents to ask desired operation, L _RSRepresent that a subframe includes the OFDM symbolic number of RS, N _RSBe illustrated in the sub-carrier number that comprises RS in the OFDM symbol,

The frequency domain channel estimated result of locating for RS position (k ', l '),

Be the received signal that RS position (k ', l ') locates, x _{K ', l '}The transmission signal of locating for RS position (k ', l ').

8. the method for noise testing according to claim 7 is characterized in that, described second noise measurement module specifically is to carry out the noise testing second time by following expression formula:

I wherein, j is respectively the index of transmitting antenna and reception antenna port, N _T, N _RRepresent number of transmit antennas and reception antenna number respectively.

9. a MIMO-OFDM system terminal receiving system is characterized in that, comprising:

First noise measurement module is used for carrying out the noise testing first time according to the frequency domain data after the FFT conversion;

Channel estimation module is used to utilize the measurement result of described first noise measurement module to carry out channel estimating;

Second noise measurement module is used for according to the frequency domain data after the FFT conversion, and the estimated result of described channel estimation module carries out the noise testing second time;

The MIMO detection module is used to utilize the measurement result of described second noise measurement module to detect.

10. MIMO-OFDM system terminal receiving system according to claim 9 is characterized in that, also comprises:

The channel decoding module is used to utilize the measurement result of described second noise measurement module to carry out the decoding processing of chnnel coding; And/or

Feedback module is used to utilize the measurement result of described second noise measurement module to carry out feedback calculation.

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