CN101908935B - System for estimating signal-to-noise ratio of signal in multiple carrier system - Google Patents

Abstract

The invention provides a system for estimating the signal-to-noise ratio of a signal in a multiple carrier system. The invention provides the system for estimating the signal-to-noise ratio of the signal based on a blind transmit parameter signaling (TPS) or a pilot signal in the multiple carrier system. The system of the invention comprises a phase rotation device, an energy estimation device, a channel gain calculation device, a selection average device, a combination and calculation device and a dB value conversion device. By the invention, the signal-to-noise ratio of the signal can be estimated to correct a communication system to be in a better condition without checking up the contents of the TPS or the pilot signal in advance.

Description

Estimation system for signal-to-noise ratio of signal in multi-carrier system

Technical Field

The present invention relates to the field of signal transmission technology, and more particularly, to a system for estimating signal-to-noise ratio of a signal in a multi-carrier system.

Background

Efficient and accurate signal to noise ratio (SNR) estimation is essential in communication systems. Especially when a Multi-carrier (Multi-carrier) system including OFDM or TDS-OFDM is operated in a Multi-path fading channel (Multi-fading channel), efficient and accurate snr information is required to improve system performance.

Xu et al, 2005, at IEEE 61st Vehicular Technology Conference: in "a Novel SNR Estimation Algorithm for OFDM", a prior SNR Estimation method is disclosed, and a second-order SNR Estimation method is proposed accordingly, which is based on the Jakes model and is suitable for fast multipath fading channel environment. However, it only estimates the signal to noise ratio on each subcarrier, not for the entire OFDM system.

Athanasios et al, 2005, incorporated by ICACT 7th International Conference on advanced Communication Technology: in "BPSK SNR estimation algorithm for HIPERLAN/2 transceiver in AWGN channels", a signal SNR estimation method in a high performance wireless local area network (HIPERLAN) has been disclosed. However, it only considers AWGN (Additive white Gaussian noise) channels, not multipath channels that are closer to the actual transmission. Therefore, the existing signal-to-noise ratio (SNR) estimation techniques are not fully considered, and there are still many disadvantages and needs to be improved.

Disclosure of Invention

The invention mainly aims to provide a system for estimating the signal-to-noise ratio of a signal used for a multi-carrier system. It is suitable for Multi-carrier (Multi-carrier) systems operating in multipath fading channels, including OFDM or TDS-OFDM based systems.

According to an aspect of the present invention, the present invention provides an estimation system for snr of a signal in a multi-carrier system without detecting the content of blind transmission parameter signaling or pilot signal in advance. It includes phase rotation means, energy estimation means, channel gain calculation means, selective averaging means, and combining and calculating means. The phase rotator performs a phase rotation operation on a received Quadrature Amplitude Modulation (QAM) symbol signal and a channel estimation signal to generate a rotated symbol signal and a rotated channel estimation signal. The energy estimation device is connected to the phase rotation device and comprises a plurality of sub-energy estimation devices for estimating the energy of the rotation QAM symbol signal in each sub-carrier, thereby generating a signal energy signal and a noise energy signal. The channel gain calculating device is connected to the phase rotating device, and generates a subcarrier channel gain signal and an average channel gain signal according to the rotating channel estimation signal. The selection averaging device is connected to the energy estimation device and the channel gain calculation device, and selects and generates an average signal power set, an aggregate average noise power and an average channel gain set according to a criterion signal, the signal energy signal, the noise energy signal and the subcarrier channel gain signal. The combination and calculation device is connected with the selection average device and the channel gain calculation device, and generates an estimated signal-to-noise ratio according to the criterion signal, the average signal power set, the set average noise power, the average channel gain set and the average channel gain signal.

Drawings

Fig. 1 is a system for estimating snr of a signal in a multi-carrier system according to the present invention, which is suitable for a multi-carrier system operating in a multipath fading channel and mainly including OFDM or TDS-OFDM.

FIG. 2 is a block diagram of a sub-energy estimation apparatus according to the present invention.

FIG. 3 is a block diagram of another embodiment of a sub-energy estimation apparatus according to the present invention.

Fig. 4 is a block diagram of a channel gain calculation apparatus according to the present invention.

Fig. 5 is a block diagram of the selective averaging apparatus of the present invention.

FIG. 6 is a block diagram of the candidate search apparatus according to the present invention.

FIG. 7 is a block diagram of the combination and computing device of the present invention.

Fig. 8 is a diagram illustrating simulation results of the system for estimating signal-to-noise ratio of blind transport parameter signaling or pilot signal in dmb according to the present invention.

Fig. 9 is a diagram illustrating another simulation result of the estimation system for signal-to-noise ratio of a multi-carrier system of the present invention.

Fig. 10 is a diagram of various parameters of the SARFT-8 multipath channel.

Description of the main elements

Phase rotation apparatus 110 of estimation system 100

Energy estimation device 120 channel gain calculation device 130

Selection averaging device 140 combination and calculation device 150

dB value conversion device 160

Delay device 210 of sub-energy estimation device 121

Complex valued means 215, 220 multipliers 225, 230

Real value taking device 235 subtracter 240

Register 250 accumulator 245, 255

Complex value taking device 310, 360 accumulating device 320, 340

Multiplier 330, 370 subtracter 380

Temporary memory 350

Register 410 first accumulator 420

First multiplier 430 first selection means 440

Second accumulation device 450

Third accumulation device 510 candidate search device 520

Second selection means 530

Candidate selecting device 610 number calculating device 620

First computing device 710 second computing device 720

Third computing device 730 third selecting device 740

Detailed Description

Fig. 1 is a block diagram of a system 100 for estimating snr of a multi-carrier system according to the present invention, which is suitable for a multi-carrier system operating in a multipath fading channel and including OFDM or TDS-OFDM. The synchronization and channel estimation functions required by the estimation system are assumed to be performed in advance, and are not included in the scope of the present invention.

The estimation system 100 comprises a phase rotation device 110, an energy estimation device 120, a channel gain calculation device 130, a selective averaging device 140, a combining and calculating device 150, and a dB value conversion device 160.

Let i denote the index (index) of the code frame (frame) and k denote the index of the sub-carrier (sub-carrier). The phase rotating device 110 will receive the QAM symbol signal Y_i，kAnd channel estimation signals

Performing a phase rotation operation to generate a rotated QAM symbol signal

And a rotating channel estimation signal

Order to $H_{i,k}=\left|H_{i,k}\right|\·e^{j\∠H_{i,k}},$ And perfect channel estimation is assumed so that ${\hat{H}}_{i,k}=H_{i,k},$ The phase rotating device 110For QAM symbol signal { Y_i，kAnd channel estimation signalsRespectively rotate the negative angle H_i，kAngle, to generate the rotated QAM symbol signal

And the rotating channel estimation signal

The rotated QAM symbol signal

Can be expressed by the following formula:

${\tilde{Y}}_{i,k}=Y_{i,k}\·e^{-j\∠H_{i,k}},$

the rotating channel estimation signal

Can be expressed by the following formula:

${\tilde{H}}_{i,k}=H_{i,k}\·e^{-j\∠H_{i,k}}=\left|H_{i,k}\right|,$

let n be the time-domain QAM symbol sequence { y_i，nThe index of. Then { Y_i，kIs { y }_i，nAnd expressing the sequence in the frequency domain after FFT operation.

The energy estimation device 120 is connected to the phase rotation device 110 and comprises N_TPSA sub-energy estimation device 121 for estimating the sub-energy of the rotated QAM symbol signal

Energy estimation is performed in each sub-carrier to generate a signal energy signal S^TAnd noise energy signal N^T。

FIG. 2 is a block diagram of the sub-energy estimation devices 121 of the present invention, wherein each sub-energy estimation device 121 is an associated energy estimation device that receives the rotated QAM symbol signal

Of the frequency domain signal

And generates a signal energy signal S on a subcarrier_kAnd noise energy signal N_k. As shown in FIG. 2, the sub-energy estimation device 121 comprisesComprising delay means 210, complex value extracting means 215, 220, multipliers 225, 230, real value extracting means 235, subtracter 240, register 250, and accumulating means 245, 255.

The delay device 210 receives the frequency domain signalAnd temporarily storing. The complex value extractor 215 is connected to the delay device 210 to extract the complex value of the temporary storage signal, and then the multiplier 225 extracts the complex value of the temporary storage signal and the frequency domain signal

Multiplying the result by a real value extractor 235 to generate a signal S_i，k。

The complex value obtaining device 220 is used for obtaining the frequency domain signal

After taking the complex value, the multiplier 230 and the frequency domain signal are utilized

Multiply to generate a signal P_i，kSignal P_i，kCan be regarded as the total energy on the k sub-carrier, and the signal S_i，kCan be considered as the signal energy on the k sub-carrier. So when the signal P_i，kSubtracting the signal S by a subtractor 240_i，kSignal N generated thereafter_i，kCan be considered as the noise energy on the k-th subcarrier.

The register 250 temporarily stores the number N of frames to be accumulated_sThe summation means 245, 255 each pair signal S_i，kAnd signal N_i，kIs added up to generate the signal energy signal S_kAnd noise energy signal N_kThe signal energy signal S_kAnd noise energy signal N_kCorresponding to the k-th subcarrier.

The energy estimation device 120 has N_TPSSub energyAn estimation device 121, each sub-energy estimation device 121 outputting a signal energy signal S_kAnd noise energy signal N_kIs the signal energy signal S^TAnd the noise energy signal N^T。

FIG. 3 is a block diagram of another embodiment of the sub-energy estimation devices 121 according to the present invention, wherein each sub-energy estimation device 121 is a time-averaged energy estimation device that receives the rotated QAM symbol signal

Of the frequency domain signalAnd generates a signal energy signal S on a subcarrier_kAnd noise energy signal N_k. As shown in fig. 3, the sub-energy estimation device 121 includes complex value obtaining devices 310, 360, accumulating devices 320, 340, multipliers 330, 370, a subtractor 380, and a register 350.

The complex value obtaining device 310 receives the frequency domain signal

And takes the complex value, then the multiplier 330 will take the complex value signal and the frequency domain signal

Multiply to generate a signal P_i，kSignal P_i，kCan be considered as the total energy on the k sub-carrier. The register 350 temporarily stores the number N of frames to be accumulated_sThe summation device 340 sums the signal P_i，kIs added up to generate the signal P_k。

The summation device 340 sums up the frequency domain signal

The complex value calculator 360 is connected to the accumulator 340 for calculating the complex value of the output signal of the accumulator 340. Use theThe multiplier 370 is connected to the accumulation device 340 and the complex value obtaining device 360 for multiplying the output signal of the accumulation device 340 and the output signal of the complex value obtaining device 360 to generate the signal energy signal S_k. The subtractor 380 converts the signal P_kSubtracting the signal energy signal S_kTo generate the noise energy signal N_k。

The energy estimation device 120 has N_TPSSub-energy estimation means 121, each sub-energy estimation means 121 outputting a signal energy signal S_kAnd noise energy signal N_kIs the signal energy signal S^TAnd the noise energy signal N^T。

The channel gain calculating device 130 is connected to the phase rotating device 110, and estimates the signal according to the rotating channel

To generate a subcarrier channel gain signal P_H ^TAnd an average channel gain signal P_H。

Fig. 4 is a block diagram of the channel gain calculating device 130 according to the present invention, wherein the channel gain calculating device 130 comprises a register 410, a first accumulating device 420, a first multiplier 430, a first selecting device 440, and a second accumulating device 450.

The register 410 stores the number of frames N_F. The first accumulating means 420 is connected to the register 410 and the phase rotating means 110 for estimating the rotated channel estimation signal

Performing an accumulation operation to generate an accumulated estimated signal of the rotating channel

The first multiplier 430 is coupled to the first accumulating means 420 for accumulating the rotated channel estimated signal

Multiplying to produce a k sub-carrier channel gain

The first selection device 440 is connected to the first multiplier 430 for selecting a subcarrier as a channel gain corresponding to a Transmission Parameter Signaling (TPS) or pilot signal (pilot) to generate the subcarrier channel gain signal P_H ^T。

The second summation device 450 is coupled to the first multiplier 430, and gains all sub-carrier channels

Performing an accumulation operation to generate the average channel gain signal P_H。

Wherein the k sub-carrier channel gain

Can be expressed by the following formula:

$P_{H_k}={\left((1/N_F){\mathrm{\Σ}}_i^{N_F}\right|H_{i,k}\left|\right)}^2,$

the average channel gain signal P_HCan be expressed by the following formula:

${\stackrel{\‾}{P}}_H=(1/M){\mathrm{\Σ}}_{k=1}^M{P}_{H_k},$

the subcarrier channel gain signal P_H ^TCan be expressed by the following formula:

$P_H^T\≡\left\{P_{H_k}\right|k\∈I_T\},$

wherein, I_TThe subcarriers are a set formed by indexes of transmission parameter signaling or pilot signals.

The selective averaging means 140 is connected to the energy estimation means 120 and the channel gain calculation means 130, and is based on a criterion signal mu, the signal energy signal S^TThe noise energy signal N^TAnd the sub-carrier channel gain signal P_H ^TSelectingAnd generating an average signal power set

Aggregate average noise power

And average channel gain set

Fig. 5 is a block diagram of the selective averaging device 140 according to the present invention, wherein the selective averaging device 140 comprises a third accumulating device 510, a candidate searching device 520, and a second selecting device 530.

The third accumulation device 510 is connected to the energy estimation device 120 and the first selection device 440 for the signal energy signal S^TThe noise energy signal N^TAnd the sub-carrier channel gain signal P_H ^TThe accumulation operation is performed to generate an average signal power S, an average noise power N, and an average channel gain P. That is, the third accumulation device 510 has three sub-accumulation devices for respectively accumulating the signal energy signal S^TThe noise energy signal N^TAnd the sub-carrier channel gain signal P_H ^TThe accumulation operation is performed to generate an average signal power S, an average noise power N, and an average channel gain P.

The candidate search means 520 is connected to the energy estimation means 120 and the first selection means 440 for selecting the signal energy signal S according to a criterion signal mu^TThe noise energy signal N^TAnd the sub-carrier channel gain signal P_H ^TPerforming search and selection to generate a set of qualified subcarrier indices V_μAnd the number N of qualified subcarrier index sets_V。

Fig. 6 is a block diagram of the candidate searching device 520 according to the present invention, wherein the candidate searching device 520 comprises a candidate selecting device 610 and a number calculating device 620.

As shown in fig. 6, the average signal power is aggregated

The aggregate average noise power

And the average channel gain set

Subscript m in (1) to N_V. When the criterion signal μ is accumulation (A), the candidate search device 520 outputs the qualified subcarrier index set V_μIs a V_AK ═ 1 }. When the criterion signal mu is all (O), the candidate searching apparatus 520 outputs the qualified subcarrier index set V_μIs a V_O＝{k|k＝1～N_TPS}. When the criterion signal mu is the k sub-carrier channel gain

If the sum is greater than the threshold (η), the candidate search device 520 outputs the qualified subcarrier index set V_μIs composed ofWhen the criterion signal mu is the k-th sub-carrier maximum signal-to-noise ratio, the candidate searching apparatus 520 outputs the qualified sub-carrier index set V_μWhen the criterion signal mu is the k-th sub-carrier maximum signal power, the candidate search device 520 outputs the qualified sub-carrier index set V_μIs composed of

When the criterion signal mu is the k-th sub-carrier maximum channel gain, the qualified sub-carrier output from the candidate searching apparatus 520Set of carrier indices V_μIs composed of $V_H=\left\{k\right|\arg \underset{k}{\mathrm{Max}}\left(P_{H_k}\right)\}.$

The number calculating means 620 is connected to the candidate selecting means 610 for calculating the qualified subcarrier index set V_μNumber N of_μ. That is, N_μ＝|V_μ|。

The second selection means 530 is connected to the third accumulation means 510 and the candidate search means 520 according to the criterion signal mu, the qualified subcarrier index set V_μAnd the number N of qualified subcarrier index sets_VTo be measured by the average signal power

The average noise power

And the average channel gain

Selecting a set of average signal powers to produceAggregate average noise power

And average channel gain set

The combining and calculating means 150 is connected to the selective averaging means 140 and the channel gain calculating means 130, and is configured to calculate the average signal power set according to the criterion signal muThe aggregate average noise power

The average channel gain set

And the average channel gain signal

To generate an estimated signal-to-noise ratio gamma_μ。

FIG. 7 is a block diagram of the computing device 150 of the present invention, the computing device 150 comprising a first computing device 710, a second computing device 720, a third computing device 730, and a third selecting device 740.

The first calculating means 710 is connected to the selective averaging means 140 and the channel gain calculating means 130 according to the average signal power set

The aggregate average noise power

And the average channel gain set

Thereby generating a first estimated signal noise. The first computing device 710 generates the first estimated signal noise according to the following equation:

${\mathrm{\γ}}_1=\frac{{\tilde{S}}_1^{\mathrm{\μ}}}{{\tilde{N}}_1^{\mathrm{\μ}}}\·\frac{{\stackrel{\‾}{P}}_H}{{\tilde{P}}_1^{\mathrm{\μ}}}.---\left(1\right)$

the second calculating means 720 is connected to the selective averaging means 140 and the channel gain calculating means 130 according to the average signal power set

The aggregate average noise power

The average channel gain set

And the average channel gain signal P_HAnd second estimated signal noise is generated. The second computing device 720 generates the second estimated signal noise according to the following equation:

${\mathrm{\γ}}_2=\frac{{\stackrel{\‾}{P}}_H\·\underset{m=1}{\overset{N_V}{\mathrm{\Σ}}}\left(\frac{{\tilde{S}}_m^{\mathrm{\μ}}}{{\tilde{P}}_m^{\mathrm{\μ}}}\right)}{\underset{m=1}{\overset{N_V}{\mathrm{\Σ}}}\left({\tilde{N}}_m^{\mathrm{\μ}}\right)}.---\left(2\right)$

the third calculating means 730 is connected to the selective averaging means 130 and the channel gain calculating means 140 according to the average signal power set

The aggregate average noise power

The average channel gain set

And the average channel gain signal P_HAnd a third estimated signal noise is generated. The third computing device 730 generates the third estimated signal noise according to the following formula:

${\mathrm{\γ}}_3={\stackrel{\‾}{P}}_H\·\{\underset{m=1}{\overset{N_V}{\mathrm{\Π}}}\frac{{\tilde{S}}_m^{\mathrm{\μ}}}{{\tilde{N}}_m^{\mathrm{\μ}}}\·\frac{1}{{\tilde{P}}_m^{\mathrm{\μ}}}\}.---\left(3\right)$

the third selection device 740 is connected to the first calculation device 710, the second calculation device 720, and the third calculation device 730, and selects the first estimation signal noise, the second estimation signal noise, and the third estimation signal noise according to the criterion signal mu to output as the estimation signal SNR γ_μ。

The dB value conversion device 160 is connected to the combination and calculation device 150 to convert the estimated signal-to-noise ratio γ_μConverted to dB values.

From the foregoing description, it can be seen that the present techniques are applicable to multipath channels. When the inventive technique is applied to an AWGN channel, the signal-to-noise ratio gamma of the signal is estimated_μComprises the following steps:

${\mathrm{\γ}}_{\mathrm{\μ}}={\left\{\underset{m=1}{\overset{N_V}{\mathrm{\Π}}}\frac{{\tilde{S}}_m^{\mathrm{\μ}}}{{\tilde{N}}_m^{\mathrm{\μ}}}\right\}}^{\frac{1}{N_V}}.---\left(4\right)$

fig. 8 is a diagram illustrating simulation results of an estimation system for signal-to-noise ratio of blind transmission parameter signaling or pilot signals according to the present invention, which uses 36 pilot signals under AWGN, and uses the correlated sub-energy estimation device 121 and the criterion signal μ in fig. 2 as an accumulation (μ ═ a). As can be seen from FIG. 8, in both PN945 and PN420 modes, when the signal-to-noise ratio is less than 22dB, the difference between the estimated signal-to-noise ratio (dB) and the actual measured signal-to-noise ratio (dB) is less than 1 dB. That is, the estimated signal to noise ratio (dB) of the inventive technique is very close to the actual value.

Fig. 9 is another schematic diagram of an analog representation of the snr estimation system for blind transport parameter signaling or pilot signals in dmb for SARFT-8 multipath channel in PN420/QPSK mode according to the present invention, wherein the M1 line uses the formula (3) of the correlated sub-energy estimation apparatus 121 in fig. 2, the M2 line uses the formula (3) of the time-averaged sub-energy estimation apparatus 121 in fig. 3, and the M3 line uses the formula (1) of the correlated sub-energy estimation apparatus 121 in fig. 2. Fig. 10 is a diagram of various parameters in a SARFT-8 multipath channel.

As can be seen from the foregoing description, the prior art does not consider using transmission parameter signaling or pilot signals to aid signal-to-noise ratio (SNR) estimation, but only consider AWGN channels, and does not consider multipath channels in actual transmission. The present invention uses transmission parameter signaling or pilot signals to help signal-to-noise ratio estimation, which can estimate the signal-to-noise ratio more accurately than the prior art, so that the communication system can be calibrated to a better condition. Meanwhile, the invention not only considers the AWGN channel, but also considers the transmission situation of the multi-path channel during actual transmission, and can estimate the signal-to-noise ratio of the signal during actual transmission more accurately than the prior art.

From the above, the present invention shows features different from the prior art in terms of the purpose, means and efficacy, and has great practical value. It should be noted that the above-mentioned embodiments are merely examples for convenience of description, and the scope of the claims of the present invention should be determined by the appended claims rather than by the foregoing examples.

Claims (18)

1. An estimation system for signal to noise ratio of a signal for a multi-carrier system, the estimation system comprising:

phase rotation device for receiving QAM symbol signal { Y_i，kAnd channel estimation signalsFollowed by a phase rotation operation to produce a rotated QAM symbol signal

And a rotating channel estimation signal

An energy estimation device connected to the phase rotation device and including N_TPSA sub-energy estimation device for estimating sub-energy of the rotated QAM symbol signal

Energy estimation is performed in each sub-carrier to generate a signal energy signal S^TAnd noise energy signal N^TIn which N is_TPSIs a positive integer;

a channel gain calculating device connected to the phase rotating device for estimating the signal according to the rotating channel

To generate a subcarrier channel gain signal

And averaging the channel gain signal

A selective averaging device connected to the energy estimation device and the channel gain calculation device, based on the criterion signal mu, the signal energy signal S^TThe noise energy signal N^TAnd the sub-carrier channel gain signal

Selecting and generating a set of average signal powers

Aggregate average noise power

And average channel gain setAnd

a combination and calculation device connected to the selection average device and the channel gain calculation device, for calculating the average signal power set according to the criterion signal muThe aggregate average noise power

The average channel gain set

And the average channel gain signal

To generate an estimated signal-to-noise ratio gamma_μ；

Wherein, the channel gain calculating device comprises:

a register for storing the number N of frames_F；

A first accumulation device connected to the register and the phase rotation device for estimating the rotating channelPerforming an accumulation operation to generate an accumulated estimated signal of the rotating channel

A first multiplier coupled to the first accumulation device for multiplying the accumulated rotated channel estimated signal

Multiplying to produce a k sub-carrier channel gain

A first selection device connected to the first multiplier for selecting the sub-carrier as the channel gain corresponding to the transmission parameter signaling or the pilot signal to generate the sub-carrier channel gain signal

And

a second accumulation device connected to the first multiplier for all sub-carrier channel gainsPerforming an accumulation operation to generate the average channel gain signal

Wherein the selective averaging means comprises:

a third accumulation device connected to the energy estimation device and the first selection device for accumulating the signal energy signal S^TThe noise energy signal N^TAnd the sub-carrier channel gain signal

Performing an accumulation operation to generate average signal powers

Average noise powerAnd average channel gain

Candidate search means, connected to the energy estimation means and the first selection means, for searching the signal energy signal S according to a criterion signal mu^TThe noise energy signal N^TAnd the sub-carrier channel gain signal

Performing search and selection to generate a set of qualified subcarrier indices V_μAnd the number N of qualified subcarrier index sets_V(ii) a And

a second selection device connected to the third accumulation device and the candidate search device, for selecting the qualified subcarrier index set V according to the criterion signal mu_μAnd the number N of qualified subcarrier index sets_VTo be measured by the average signal power

The average noise power

And the average channel gainSelecting a set of average signal powers to produceAggregate average noise powerAnd average channel gain set

Wherein, the combination and calculation device comprises:

a first calculating device connected to the selection averaging device and the channel gain calculating device for calculating the average signal power set

The aggregate average noise power

And the average channel gain set

Generating a first estimated signal noise;

a second calculating device connected to the selection averaging device and the channel gain calculating device for calculating the average signal power setThe aggregate average noise power

The average channel gain set

And the average channel gain signal

Generating a second estimated signal noise;

a third calculating device connected to the selective averaging device and the channel gain calculating device according to the average signal power setThe aggregate average noise power

The average channel gain set

And the average channel gain signalGenerating a third estimated signal noise; and

a third selection device connected to the first computing device, the second computing device, and the third computing device,selecting the first estimated signal noise, the second estimated signal noise and the third estimated signal noise according to the criterion signal mu to output as the estimated signal-to-noise ratio gamma_μ。

2. The evaluation system of claim 1, further comprising:

dB value conversion device connected to the combination and calculation device to convert the signal-to-noise ratio gamma of the estimated signal_μConverted to dB values.

3. The estimation system of claim 2, wherein the phase rotation means is responsive to the QAM symbol signal { y_i，kAnd channel estimation signals

Respectively rotate the negative angle H_i，kAngle, to generate the rotated QAM symbol signal

And the rotating channel estimation signal

4. The estimation system of claim 3, wherein the rotated QAM symbol signal

Can be expressed by the following formula:

${\tilde{Y}}_{i,k}=Y_{i,k}\·e^{-j\∠H_{i,k}},$

the rotating channel estimation signal

Can be expressed by the following formula:

${\tilde{H}}_{i,k}=H_{i,k}\·e^{-j\∠H_{i,k}}=\left|H_{i,k}\right|,$

wherein,

for the rotated QAM symbol signal

The frequency domain representation of (a).

5. The estimation system of claim 4 wherein each of the sub-energy estimation devices includes an associated energy estimation device.

6. The estimation system of claim 4 wherein each of the sub-energy estimation devices comprises a time-averaged energy estimation device.

7. The estimation system of claim 6 wherein the kth sub-carrier channel gainCan be expressed by the following formula:

$P_{H_k}={\left((1/N_F){\mathrm{\Σ}}_i^{N_F}\right|H_{i,k}\left|\right)}^2,$

the average channel gain signal

Can be expressed by the following formula:

${\stackrel{\‾}{P}}_H=(1/M){\mathrm{\Σ}}_{k=1}^M{P}_{H_k},$

the subcarrier channel gain signal

Can be expressed by the following formula:

$P_H^T\≡\left\{P_{H_k}\right|k\∈I_T\},$

wherein, I_TSet of indices for transmission parameter signalling or pilot signals for sub-carriers, N_FIs the number of frames.

8. The estimation system of claim 7 wherein the set of average signal powers

The aggregate average noise power

And the average channel gain set

Subscript m in (1) to N_V。

9. The estimation system of claim 8 wherein the candidate search means outputs the qualified subcarrier index set V when the criterion signal μ is accumulation (a)_μIs a V_A＝{k|k＝1}。

10. The estimation system of claim 9, wherein the set of qualified subcarrier indexes V output by the candidate search means is set when the criterion signal μ is all (O)_μIs a V_O＝{k|k＝1～N_TPS}。

11. The estimation system of claim 10, wherein when the criterion signal μ is the k-th sub-carrier channel gain

When the sum is greater than the threshold eta, the qualified subcarrier index set V output by the candidate searching device_μIs composed of

12. The estimation system of claim 11 wherein the qualified subcarrier index set V output by the candidate search means when the criterion signal μ is the kth subcarrier maximum signal-to-noise ratio_μIs composed of

Wherein S is_kFor the kth sub-carrier signal energy signal, N_kIs the k sub-carrier noise energy signal.

13. The evaluation system of claim 12, wherein when the evaluation system is in operationWhen the criterion signal mu is the maximum signal power of the k-th sub-carrier, the qualified sub-carrier index set V outputted by the candidate searching device_μIs composed of

Wherein,is the kth subcarrier signal power.

14. The estimation system of claim 13 wherein the qualified subcarrier index set V output by the candidate search means when the criterion signal μ is the kth subcarrier maximum channel gain_μIs composed of

15. The estimation system of claim 14 wherein the first calculation means generates the first estimated signal noise according to the following equation:

${\mathrm{\γ}}_1=\frac{{\tilde{S}}_1^{\mathrm{\μ}}}{{\tilde{N}}_1^{\mathrm{\μ}}}\·\frac{{\stackrel{\‾}{P}}_H}{{{\tilde{P}}_1}^{\mathrm{\μ}}},$

wherein,

is the set of average signal power

The middle subscript m is an item of 1,

average noise power for the set

The middle subscript m is an item of 1,

is the average channel gain set

The middle subscript m is 1.

16. The estimation system of claim 15 wherein the second calculation means generates the second estimated signal noise according to the following equation:

${\mathrm{\γ}}_2=\frac{{\stackrel{\‾}{P}}_H\·\underset{m=1}{\overset{N_V}{\mathrm{\Σ}}}\left(\frac{{\tilde{S}}_m^{\mathrm{\μ}}}{{\tilde{P}}_m^{\mathrm{\μ}}}\right)}{\underset{m=1}{\overset{N_V}{\mathrm{\Σ}}}\left({\tilde{N}}_m^{\mathrm{\μ}}\right)}.$

17. the estimation system of claim 16 wherein the third calculation means generates the third estimated signal noise according to the following equation:

${\mathrm{\γ}}_3={\stackrel{\‾}{P}}_H\·\{\underset{m=1}{\overset{N_V}{\mathrm{\Π}}}\frac{{\tilde{S}}_m^{\mathrm{\μ}}}{{\tilde{N}}_m^{\mathrm{\μ}}}\·\frac{1}{{\tilde{P}}_m^{\mathrm{\μ}}}\}.$

18. the estimation system of claim 16 wherein the signal to noise ratio γ is estimated in an AWNG channel_μComprises the following steps:

${\mathrm{\γ}}_{\mathrm{\μ}}={\left\{\underset{m=1}{\overset{N_V}{\mathrm{\Π}}}\frac{{\tilde{S}}_m^{\mathrm{\μ}}}{{\tilde{N}}_m^{\mathrm{\μ}}}\right\}}^{\frac{1}{N_V}}.$

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