WO2011032379A1

WO2011032379A1 - Method and device for estimating carrier to interference and noise ratio in orthogonal frequency division multiplexing system

Info

Publication number: WO2011032379A1
Application number: PCT/CN2010/071614
Authority: WO
Inventors: 余秋星; 陈琼; 韩亚洁; 刘巧艳
Original assignee: 中兴通讯股份有限公司
Priority date: 2009-09-17
Filing date: 2010-04-07
Publication date: 2011-03-24
Also published as: CN102025426B; CN102025426A

Abstract

The present application discloses a method and device for estimating a carrier to interference and noise ratio in an orthogonal frequency division multiplexing system, which is comprised of dividing pilot sub-carriers of each pilot symbol in a sub-frame into groups, getting the second order difference of the estimated channel response value in each pilot sub-carrier group of each pilot symbol(S101); getting an interference and noise item in each pilot sub-carrier group of each pilot symbol according to the second order difference(S102); getting the average interference and noise power of pilot symbols in the sub-frame according to the interference and noise item of each pilot sub-carrier group(S103);getting the total average power of pilot symbols in the sub-frame(S104); getting the carrier to interference and noise ratio according to the average interference and noise power and the total average power(S105).The method and device provided by the present application can improve estimating accuracy of the carrier to interference and noise ratio.

Description

Method and device for estimating carrier interference noise ratio in orthogonal frequency division multiplexing system

The present invention relates to the field of communication technologies, and in particular, to a method and apparatus for estimating a carrier interference to noise ratio in an orthogonal frequency division multiplexing system. Background technique

In recent years, OFDM (Orthogonal Frequency Division Multiplexing) technology has been widely concerned as a multi-carrier transmission technology. OFDM technology converts input serial data into parallel transmission data, and modulates the parallel data onto a plurality of subcarriers, that is, subchannels having orthogonality, and then transmits the modulated data.

OFDM technology has been successfully applied to asymmetric digital subscriber loops (ASDL, Asymmetric)

Digital Subscriber Line), Digital Audio Broadcasting (DAB), High-definition Television (HDTV), Wireless Local Area Network (WLAN), Global Interconnected WiMAX ( Worldwide Interoperability) For Microwave Access), Long Term Evolution (LTE) systems. Orthogonal Frequency Division Multiplexing (OFDM) is a new generation wireless access technology based on OFDM modulation, which effectively combines access and modulation.

In an OFDM system, each subcarrier contains two parts of power, one is signal power, and the other is interference noise power. The carrier to interference ratio (CINR) is the expected user occupied subcarrier within a certain time range. The ratio of the total signal power to the total power of the interference noise may also be the ratio of the average power of the signal on the subcarrier and the average power of the interference noise expected by the user in a certain time range. The carrier-to-interference and noise ratio is an important parameter reflecting the channel quality. It is estimated that the carrier-to-interference and noise ratio is self-determined by the OFDM system. Adaptive Modulation Coding (AMC). Required for power control and resource allocation. In the LTE system, the carrier-to-noise-and-noise ratio is still a necessary statistic for performing closed-loop MIMO (Multiple Input Multiple Output). In addition, for the performance improvement of key algorithms involved in the MIMO-OFDM system, such as the channel estimation algorithm and the MIMO algorithm, it is often necessary to measure the accurate interference noise power.

The basic transmission unit of LTE is 1 subframe, with a time interval of 1 millisecond. Take the structure of the LTE downlink subframe shown in Figure 1 as an example. & ( = 1, 2, 3, 4, j = U in Figure 1 The number of pilot subcarriers indicates the pilot signal transmitted on the 'the first pilot subcarrier on the first pilot symbol. After passing through the channel, the corresponding received signal is:

(1) wherein, the interference noise signal transmitted on the first pilot subcarrier on the first pilot symbol, Α, represents the channel response on the first pilot subcarrier on the first pilot symbol.

After correlation with ·, the estimated value of the channel response transmitted on the first pilot subcarrier on the first pilot symbol can be obtained ,", Η" is the channel response and the ith pilot symbol The sum of the interference noises carried on the pilot subcarriers, as shown in equation (2):

Where ^ ^ W/', , and ^ are conjugated. Since ^ is a known signal with a mode of 1, ^ ^ has the same power and is expressed.

The existing CINR estimation method is based on that the adjacent subcarriers have substantially the same channel characteristics in the pilot symbols, so the difference between the correlation values is the value of the interference and noise components in which the signal components are eliminated, that is, the hypothesis H" - ^H "" or H" ^{= Η} , summing all interference and noise components, then calculating the total interference and noise work and then based on the total power of the signal and interference noise ^, Estimate CINR using equation (3):

CINR = ^PSNI ~ ^PNI

P≡ ( 3 )

This technique performs CINR estimation under the condition of ignoring the effects of frequency selective fading. In the case where there is no frequency selective fading of the channel experienced by the signal, the accuracy of the CINR estimation is higher. However, usually the channel experienced by the signal has frequency selective fading. The error of the assumption of the technical solution is large, which may cause the estimated noise interference power to be too large, so that the estimated signal power is too small, and finally the carrier interference noise ratio is The estimated value is smaller than the actual value. The more serious the frequency selective fading, the larger the estimation error of the carrier-to-interference and noise ratio. Especially at higher signal-to-noise ratios, the estimation error is very large, and even the flat top phenomenon occurs, so that the estimated CINR is much smaller than the actual one. CINR value. This can greatly affect the system for adaptive code modulation, power control, and resource allocation, which can greatly affect system performance. Summary of the invention

The technical problem to be solved by the present invention is to provide a method and apparatus for improving the accuracy of estimating carrier interference noise ratio in an orthogonal frequency division multiplexing system, which is to solve the problem that the carrier interference noise ratio estimation error in the prior art is large.

In order to solve the above technical problem, the technical solution of the present invention is implemented as follows:

A method for estimating a carrier interference noise ratio in an orthogonal frequency division multiplexing system, the method comprising the steps of:

S101, grouping pilot subcarriers in each pilot symbol in the subframe to obtain a second order difference value of channel estimation estimates on each group of pilot subcarriers of each pilot symbol.

S102: Obtain an interference noise item on each set of pilot subcarriers of each pilot symbol according to the second order difference value.

S103: Obtain an average interference noise power of pilot symbols in the subframe according to an interference noise item on each group of pilot subcarriers. 5104. Acquire a total average power of pilot symbols in a subframe.

5105. Acquire a carrier interference to noise ratio according to the average interference noise power and the total average power.

The grouping method is:

The adjacent three pilot subcarriers within each pilot symbol in the subframe are grouped.

In step S101, acquiring the second-order difference value includes the following steps:

51011. Obtain a difference between channel estimation estimates on the first and second pilot subcarriers in each group, and a difference in channel response estimates on the second and third pilot subcarriers.

51012, subtracting the two differences obtained in each group, and the result is the second-order difference value. In step S102, acquiring the interference noise item includes the following steps:

S 1021. The pilot symbols in the subframe are divided into two pairs according to adjacent or spaced apart.

S1022: Subtract the second-order difference value of the channel response estimation value on each set of pilot subcarriers in each pair of pilot symbols; and then subtract the subtraction result obtained by the two pairs of pilot symbols again, and obtain the result. Is the interference noise term.

In step S103, acquiring the average interference noise power of the pilot symbols in the subframe includes the following steps:

51031: Obtain a square of an interference noise term on each set of pilot subcarriers, and then sum the squares of the interference noise terms on each set of pilot subcarriers;

51032, the resulting sum value is divided by 24 times the number of packets, and the result is the average interference noise power of the pilot symbols in the subframe.

In step S101, when three adjacent pilot subcarriers in each pilot symbol in the subframe are used as a group, the packet form is:

Where = 1, 2, 3, 4, ^z ' represents the number of the pilot symbol;

Rounded down, M indicates the number of packets, m indicates the number of each group, and K indicates the pilot subcarriers. quantity.

Where = 1,2,3,4, '· indicates the number of the pilot symbol; m = \, 2, ..., M , Μ = Κ - 2 , Μ indicates the number of groups, m indicates the number of each group, K represents the number of pilot subcarriers.

An apparatus for estimating a carrier to interference and noise ratio in an orthogonal frequency division multiplexing system, the apparatus comprising: a grouping unit, configured to group pilot subcarriers in each pilot symbol in a subframe; second order difference value An acquiring unit, configured to acquire a second-order difference value of a channel response estimation value on each set of pilot subcarriers of each pilot symbol;

An interference noise item acquiring unit, configured to acquire, according to the second-order difference value, an interference noise item on each set of pilot subcarriers of each pilot symbol;

An average interference noise power acquiring unit, configured to acquire, according to an interference noise item on each set of pilot subcarriers, an average interference noise power of pilot symbols in the subframe;

And a total average power acquisition unit, configured to acquire a total average power of pilot symbols in the subframe; a carrier interference noise ratio acquisition unit, configured to acquire a carrier interference noise ratio according to the average interference noise power and the total average power.

The grouping unit is configured to group three adjacent pilot subcarriers in each pilot symbol in the subframe as a group.

The second-order difference value acquisition unit includes:

a difference subunit, configured to obtain a difference between channel estimation estimates on the first and second pilot subcarriers in each group, and a difference in channel response estimates on the second and third pilot subcarriers And a quadratic difference subunit for subtracting the two differences obtained in each group, and the result is the second order difference value.

The interference noise item acquisition unit includes: a pair of sub-units, configured to divide pilot symbols in a subframe into two pairs according to adjacent or spaced apart; an interference noise item acquisition sub-unit, configured to be used on each set of pilot subcarriers in each pair of pilot symbols The second-order difference value of the channel response estimate is subtracted; then the subtraction result obtained by the two pairs of pilot symbols is correspondingly subtracted again, and the result is the interference noise term.

The average interference noise power acquisition unit includes:

a summation subunit, configured to obtain a square of an interference noise term on each set of pilot subcarriers, and then sum the squares of the interference noise terms on each set of pilot subcarriers;

The average interference noise power acquisition sub-unit is configured to divide the sum obtained by the summation sub-unit by 24 times the number of packets, and the result is the average interference noise power of the pilot symbols in the subframe.

The beneficial effects of the present invention are as follows:

According to the characteristics of the orthogonal frequency division multiplexing system, the present invention eliminates the calculated interference noise power by processing the channel response estimation values of multiple adjacent pilot subcarriers of all pilot symbols in one subframe. The power error caused by the channel response varies with frequency and time, thereby overcoming the disadvantages of inaccurate measurement of carrier-to-interference and noise ratio due to frequency selective fading and time-selective fading of the channel, resulting in calculated signal power and interference noise. The power is more accurate, which makes the calculated carrier-to-interference and noise ratio more accurate, and thus achieves the purpose of fully utilizing the carrier-to-interference and noise ratio for adaptive code modulation, power control and resource allocation, and improving system performance, and the MIMO-OFDM system is involved. The performance improvement of key algorithms such as channel estimation algorithm and MIMO algorithm provides the required interference noise power or carrier interference noise ratio parameters, which can further improve system performance. DRAWINGS

FIG. 1 is a structural diagram of an existing LTE downlink subframe;

2 is a flowchart of a method for estimating a carrier interference noise ratio in an orthogonal frequency division multiplexing system according to Embodiment 1 of the present invention;

3 is an estimated carrier interference-to-noise ratio in an orthogonal frequency division multiplexing system according to Embodiment 2 of the present invention; Schematic diagram of the structure of the device;

4 is a schematic structural diagram of an apparatus for estimating a carrier-to-interference and noise ratio in an orthogonal frequency division multiplexing system according to Embodiment 3 of the present invention;

Fig. 5 is a comparison diagram of carrier interference noise ratios estimated by the technical solution of the present invention and the prior art. detailed description

In order to solve the problem that the estimation error of the carrier interference noise ratio in the prior art is large, the present invention provides a method and an apparatus for estimating a carrier interference noise ratio in an orthogonal frequency division multiplexing system, which will be described below with reference to the accompanying drawings and embodiments. The invention is described in further detail. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Embodiment 1 of the present invention relates to a method for estimating a carrier interference-to-noise ratio in an Orthogonal Frequency Division Multiplexing (OFDM) system. This embodiment uses the LTE downlink subframe structure shown in FIG. 1 as an example. The basic transmission unit of LTE is 1. Sub-frame, 1 ms time interval; In Figure 1, D represents the data sub-carrier,

^Pi > ( '' ^{= 1} , ² , ³ , ⁴ , j = , ² ', ^K , is the number of pilot subcarriers) represents the _th pilot subcarrier on the first pilot symbol. Indicates the pilot signal transmitted on the _th pilot subcarrier on the first pilot symbol. After passing through the channel, the corresponding received signal can be expressed as equation (1):

(1) where ^w "represents the interference noise signal transmitted on the 'the first pilot subcarrier' on the first pilot symbol, indicating the channel response on the first pilot subcarrier on the ''the first pilot symbol.

The estimated value of the channel response transmitted on the ^7th pilot subcarrier on the first pilot symbol is the sum of the channel response and the interference noise carried on the ^th pilot subcarrier on the first pilot symbol. As shown in equation (2): Where ^W j = ^NI i ' ^S ij, ^S ij and ^S j are affixed together. Since ^ is a known signal with a modulus of 1, ^^ has the same power as ^W , denoted by ^.

Although it can be considered that the closer the subcarriers in the frequency domain are, the smaller the channel response changes, but due to the frequency selective fading of the channel, the change of the adjacent subcarrier channel response is inevitable. At the same time, due to the temporal selective fading of the channel, the channel response corresponding to the same subcarrier under different pilot symbols is inevitably changed. It is considered by appropriate assumptions that the channel response in the channel response estimation of the corresponding subcarrier can be cancelled by the corresponding calculation, and the channel frequency selective fading and time selective fading can be overcome, thereby obtaining the pilot symbol in the subframe. The average interference noise power is obtained, and the corresponding carrier-to-interference and noise ratio is obtained according to the average interference noise power and the total average power.

Referring to FIG. 2, a method for estimating a carrier interference noise ratio in an orthogonal frequency division multiplexing system according to this embodiment includes the following steps:

S101. Group three adjacent pilot subcarriers in each pilot symbol in a subframe into a group, and then divide into three groups, and then obtain channel response on each group of pilot subcarriers of each pilot symbol. The second-order difference value of the estimate.

First, grouping is performed, and the grouping method includes two types. The first method of grouping is: grouping the pilot subcarriers within each pilot symbol into three groups of three adjacent pilot subcarriers, each group having no identical pilot subcarriers. The specific grouping form is:

among them,

L'" indicates rounding down, M indicates the number of packets, m indicates the number of each group, and K indicates the number of pilot subcarriers.

For example, if K=7, then M=2, m=l, 2. It is divided into two groups, namely: ^Η ;'' ^Η ' ^Η ^ And ^Ά,Η^ This grouping method needs to explain that when Κ is not an integer multiple of 3, there is a problem that it cannot be divisible. Therefore, the pilot subcarriers that are not in the last two bits or bits and cannot be divisible must be divisible. give up.

The second grouping method is: using three adjacent pilot subcarriers in each pilot symbol as a group; and two pilot subcarriers of the last two bits in the group, and adjacent to the above three The next pilot subcarrier adjacent to the pilot subcarrier is taken as the next group, and so on, and grouped. The packet form is specifically as follows: where = 1, 2, 3'4, indicating the number of the pilot symbol; m = l, 2, -, M, _M ^ K - 2 , M indicates the number of packets, and m indicates the number of each group , K represents the number of pilot subcarriers.

For example, K=7, then M=5, m=l, 2, 3, 4, 5. It is divided into 5 groups, and the 5 groups are:

It can be seen from the comparison of the two methods that in the case where the number of pilot subcarriers is the same, the second packet method can obtain more packets, and there is no problem of discarding the last pilot subcarrier. The more the group, the more accurate the carrier-to-noise ratio is. Therefore, in the same case, the second middle grouping method is preferred.

It should be noted that, the manner in which the pilot subcarriers are grouped is not limited to being a group of three adjacent pilot symbols in the subframe, but may also be changed according to an actual application scenario. The number of frequency subcarriers is used to group multiple pilot subcarriers by using the actually determined packet mode and number; as long as the pilot subcarriers can be smoothly grouped, and based on this, the problem of the prior art carrier interference noise ratio estimation error is solved. Just fine.

In the following, the technique of the present invention will be further described by taking as an example the grouping of three adjacent pilot subcarriers within each pilot symbol in a subframe as a group.

After grouping, the following steps are also included:

S1011: Obtain a difference between channel estimation estimates on the first and second pilot subcarriers in each group, And a difference in channel response estimates on the second and third pilot subcarriers;

S1012, subtracting the two differences obtained in each group, and the result is the second-order difference value. The specific solution process of the above two steps is as shown in formula (4):

In the above formula, ^ζ · ^{= 1} , ² , ³ '4 , w = l, 2".., M , Η _ί , H ₂ , respectively represent the first of the mth group of pilot subcarriers in the first pilot symbol Channel response values of the second and third pilot subcarriers.

S102. Obtain an interference noise term on each set of pilot subcarriers of each pilot symbol according to the second order difference value. The specific solution steps are as follows:

51021, the pilot symbols in the subframe are divided into two pairs according to adjacent or spaced apart; since the LTE downlink subframe structure includes four pilot symbols, when divided into two pairs according to the adjacent, the first and second pilot symbols are A pair, the third and fourth pilot symbols are a pair; when divided into two pairs according to the interval, the first and third pilot symbols are a pair, and the second and fourth pilot symbols are a pair.

51022: Subtract the second-order difference value of the channel response estimation value on each set of pilot sub-carriers in each pair of pilot symbols; and then subtract the subtraction result obtained by the two pairs of pilot symbols again, and obtain the result. Is the interference noise term.

The difference between the second-order difference value of the channel response on the same set of pilot subcarriers of the pair of pilot symbols is equal to the difference of the corresponding second-order difference value of the other pair of pilot symbols, and the equation (5) can be obtained. The equation described:

( )

Where ^ ¹ , ² ,...,^.

Equation (5) formally reflects the difference between the second-order difference value of the channel response on the same set of pilot subcarriers of the first and third spaced pilot symbols and the correspondence between the second and fourth spaced pilot symbols. The difference of the second-order difference values of the channel responses on the group pilot subcarriers is equal. Equation (5) can also be transformed into: That is, the difference between the second-order difference values of the channel responses on the same set of pilot subcarriers of two adjacent pilot symbols, and the corresponding group of pilot subcarriers on the third and fourth adjacent pilot symbols. The difference of the second-order difference values of the responses is equal. It can be seen that the intervals of each pair of pilot symbols are equal. Since the channel response estimate on the pilot subcarrier can be obtained by equation (2), in the present embodiment, the estimated value of ^Δ ' is estimated to be used to obtain the interference noise average power of the pilot symbols in the subframe.

In this step, "subtracting the second-order difference value of the channel response estimation value on each set of pilot subcarriers in each pair of pilot symbols" means that, in step S1021, the pilot symbols are adjacent to each other. It is divided into two pairs, that is, the first and second pilot symbols are a pair, and the third and fourth pilot symbols are a pair. Then, the channel response estimate on the mth group of pilot subcarriers in the second pilot symbol is subtracted from the second order difference value of the channel response estimate on the mth group of pilot subcarriers in the first pilot symbol. The other pair of calculation processes including the 3rd and 4th pilot symbols is identical to the calculation process of the first pair. The correspondence here is to correspond to the group number of the pilot subcarriers in the frequency symbol, that is, the group number is the same.

In this step, "reducing the subtraction result of the two pairs of pilot symbols again correspondingly" refers to using the second order of the channel response estimate on each set of pilot subcarriers corresponding to the first pair of pilot symbols. The difference value subtraction result is corresponding to subtracting the second-order difference value subtraction result of the channel response estimation value on each corresponding group of pilot subcarriers in the second pair of pilot symbols. For example: It is assumed that the pilot symbols are divided into two pairs according to the adjacent, that is, the first and second pilot symbols are a pair, and the third and fourth pilot symbols are a pair. Transmitting the channel response estimate on the mth group of pilot subcarriers in the second pilot symbol by the second order difference value of the channel response estimate on the mth group of pilot subcarriers in the first pilot symbol, Obtaining a channel response estimate difference on the mth group of pilot subcarriers of the first pair of pilot subcarriers. Then subtracting the channel response estimate on the mth group of pilot subcarriers in the 4th pilot symbol by the second order difference value of the channel response estimate on the mth group of pilot subcarriers in the 3rd pilot symbol, Obtaining a channel response estimate difference on the mth group of pilot subcarriers of the second pair of pilot subcarriers, and using the first pair of pilot subcarriers The channel response estimate difference on the mth group of pilot subcarriers minus the channel response estimate difference on the mth group of pilot subcarriers of the second pair of pilot subcarriers, ie, each set of pilot symbols is obtained Interference noise term on the pilot subcarrier. Corresponding to this calculation, it is also the group number corresponding to the pilot subcarriers in the pilot frequency symbol, that is, the group number is the same.

S103. Acquire an average interference noise power of pilot symbols in the subframe according to a perturbation noise item on each set of pilot subcarriers. The specific solution steps are as follows:

51031: Acquire a square of an interference noise term on each set of pilot subcarriers, and then sum the squares of the interference noise terms on each set of pilot subcarriers;

Since formula (5) is established, there are:

= ^2H l ― ^H l,ml ― ^H l,mi) ~ ( ^2H 3 ― ^H 3,ml ―

[(2H2,m2 - H ₂ , _ml ― H _{2 mi} )― (2H _{4 m2} ― H _{4 ml} - H ₄ , _m3 )]

= ( _m - -( _m - _m ) + K2W _hm2 -W _l -W _m3 )-(2W _m2 -W ₃ — ₃ , _m3 )]—

[(2fT ₂ , _m2 - ₂ , _m i - ₂ , _m3 ) - (2W ₄ , _m2 ― W^ _ml ― W _{4 m} )]

= [{^W _m2 -W _l -W _{l 3} )-{2W _il -n , _m3 )]- i _Xm -w ₁ -W ₂ , _m3 )-(2W ₄ , _m2 -W ₄ , _ml _ ₄ ,

In the above formula, _ml and W _ml ^{3⁄4 3} respectively represent interference noise of the first, second, and third pilot subcarriers in the first pilot subcarrier group in the first pilot symbol. It can be seen that if the formula (5) is established, the interference noise of the corresponding subcarrier can be obtained by eliminating the channel response in the channel estimation value of the corresponding pilot subcarrier by the above formula. Therefore, in the present embodiment, the average interference noise power is obtained by the formula (7):

Pm = ^T ∑ I ( _m - - ( - K _m ) I', where M is the number of packets, m is the number of each group, (K )u ₄ , _m ) An interference noise term on each set of pilot subcarriers of each pilot symbol is represented. In this embodiment, the corresponding interference noise can also be obtained by other forms such as ~ ^Al , TM)-d~ ^λ ^, and in order to satisfy more cases, the pilot symbols in the subframe can be obtained by formula (8). Average interference noise power:

24M _m=1 ( 8 )

Where 1, 1, 2, 3 and / ⁴ represent different pilot symbols.

5104. Acquire a total average power of pilot symbols in a subframe. The total average power ^P sN of the pilot symbols in the subframe can be obtained according to the formula (9): i _{= lj = l} ( 9 ) where = 1, ² , ³ , ⁴ , 7 = ..., ^, is the guide The number of frequency subcarriers; is an estimate of the channel response transmitted on the first pilot subcarrier on the first pilot symbol.

5105. Acquire a carrier interference to noise ratio according to the average interference noise power and the total average power. The carrier-to-interference-and-noise ratio (CINR) can be obtained according to equation (3):

CINR = ^PSNI _ ^PNI

^P ( 3 )

With the technical solution of the embodiment, the average power of the interference noise and the total average power can be conveniently obtained, and the carrier interference-to-noise ratio is obtained.

As shown in FIG. 3, Embodiment 2 of the present invention relates to an apparatus for estimating a carrier interference noise ratio in an orthogonal frequency division multiplexing system. The device includes:

The grouping unit 301 is configured to group the adjacent three pilot subcarriers in each pilot symbol in the subframe as a group.

The second-order difference value obtaining unit 302 is configured to acquire, after the grouping by the grouping unit 301, a second-order difference value of the channel response estimation value on each group of pilot sub-carriers of each pilot symbol.

The interference noise item obtaining unit 303 is configured to obtain according to the second-order difference value acquiring unit 302. The second-order difference value obtains an interference noise term on each set of pilot subcarriers of each pilot symbol. The average interference noise power obtaining unit 304 is configured to obtain, according to the interference noise item on each set of pilot subcarriers acquired by the interference noise item acquiring unit 303, the average interference noise power of the pilot symbols in the subframe.

The total average power obtaining unit 305 is configured to obtain a total average power of pilot symbols in the subframe; and obtain the total average power of the pilot symbols in the subframe according to the following formula:

γ A K ^

^P SNI = ^4Λ ^Σ _i=l Σ _j=l ΐ ^ I ² where, = 1, ² , ³ , ⁴ , = ...,^ , is the number of pilot subcarriers; is the first pilot symbol An estimate of the channel response transmitted on the first pilot subcarrier.

The carrier interference noise ratio obtaining unit 306 is configured to obtain a carrier interference noise ratio according to the average interference noise power obtaining unit 304 or the average interference power obtained by the average interference noise power and the total average power acquiring unit 305.

As shown in FIG. 4, Embodiment 3 of the present invention relates to an apparatus for estimating a carrier interference noise ratio in an Orthogonal Frequency Division Multiplexing system. The device includes:

The grouping unit 401 is configured to group the adjacent three pilot subcarriers in each pilot symbol in the subframe as a group. The grouping unit 401 further includes a first grouping subunit 4011 and/or a second grouping subunit 4012. In this embodiment, the grouping unit 401 further includes a first grouping subunit 4011 and a second grouping subunit 4012; in the specific grouping, by setting, the first grouping subunit 4011 or the second grouping subunit 4012 is selected for grouping. The first grouping subunit 4011 divides each of the three adjacent pilot subcarriers of the pilot subcarriers in each pilot symbol into one group, and each group has no repeated pilot subcarriers. The specific grouping form is:

Where = 1, 2, 3'4 , indicating the number of the pilot symbol;

L'" means rounding down, M means the number of packets, m is the number of each group, and K is the pilot subcarrier. quantity.

The second packet sub-unit 4012 groups three adjacent pilot subcarriers in each pilot symbol; and sets two pilot subcarriers of the last two bits in the group, and the three adjacent guides The next pilot subcarrier adjacent to the frequency subcarrier is taken as the next group, and so on, and grouped. The packet form is specifically: where = 1, 2, 3, 4, indicating the number of the pilot symbol; η = 1,2,···,Μ , _Μ = Κ - 2 , Μ denotes the number of packets, m denotes the number of each group, and K denotes the number of pilot subcarriers.

The second-order difference value obtaining unit 402 is configured to acquire, after the grouping by the grouping unit 401, a second-order difference value of the channel response estimation value on each set of pilot sub-carriers of each pilot symbol; wherein, the second-order difference value acquiring unit 402 further includes a difference sub-unit 4021 and a quadrature difference sub-unit 402. The primary difference subunit 4021 is configured to obtain a difference between channel estimation values on the first and second pilot subcarriers in each group, and a difference in channel response estimates on the second and third pilot subcarriers. The quadrature difference sub-unit 4022 is configured to subtract the two differences obtained in each group acquired by the first difference sub-unit 4021, and the result is the second-order difference value.

The interference noise item acquiring unit 403 is configured to acquire, according to the second-order difference value acquired by the second-order difference value acquiring unit 402, an interference noise item on each set of pilot sub-carriers of each pilot symbol; wherein, the interference noise item The acquisition unit 403 further includes a pairwise subunit 4031 and an interference noise item acquisition subunit 4032. The pairing subunit 4031 is configured to divide the pilot symbols in the subframe into two pairs according to adjacent or spaced apart; the interference noise item obtaining subunit 4032 is configured to use each of the pilot subcarriers corresponding to each pair of pilot symbols. The second-order difference value of the channel response estimation value is subtracted; then the subtraction result obtained by the two pairs of pilot symbols is correspondingly subtracted again, and the result is the interference noise term.

The average interference noise power obtaining unit 404 is configured to obtain, according to the interference noise item on each set of pilot subcarriers acquired by the interference noise item acquiring unit 403, the average interference noise power of the pilot symbols in the subframe; wherein, the average interference The noise power acquisition unit 404 further includes a summation sub-list Element 4041 and average interference noise power acquisition sub-unit 4042. The summation sub-unit 4041 is configured to obtain the square of the interference noise term on each set of pilot subcarriers, and then sum the squares of the interference noise terms on each set of pilot subcarriers; the average interference noise power acquisition subunit 4042 is used to The sum obtained by the summation sub-unit 4041 is divided by the number of packets of 24 times, and the result is the average interference noise power of the pilot symbols in the subframe.

The total average power obtaining unit 405 is configured to obtain a total average power of pilot symbols in the subframe; and the total average power of the pilot symbols in the subframe may be obtained according to the following formula:

^P NI =^ ^Λ Έ=1 Έ\ ^υ I ² where = 1, ² , ³ , ⁴ , 7 = 1,2,-,^ , is the number of pilot subcarriers; is the first pilot symbol An estimate of the channel response transmitted on the first pilot subcarrier.

The carrier-to-interference and noise ratio acquisition unit 406 is configured to obtain a carrier-to-interference and noise ratio according to the average interference noise power acquisition unit 404 or the average interference power obtained by the average interference power and the total average power acquisition unit 405.

FIG. 5 is a comparison diagram of measurement performance of an extended vehicle A channel model (EVA 70, Extended Vehicular A model) when the test channel Doppler of LTE is 70 Hz, compared with the prior art by the technical solution of the above embodiment. The abscissa in the figure represents the set carrier-to-interference noise ratio, and the ordinate represents the measured carrier-to-interference noise ratio in units of decibels (dB). The curve with triangles represents the carrier-to-noise-and-noise ratio obtained by the prior art. Curve; the circled curve represents the carrier interference noise ratio curve obtained by the above embodiment of the present invention; the curve with an asterisk indicates the true carrier interference noise ratio curve. It can be seen from the figure that the error between the measured value and the actual value of the prior art is large, and the set value exceeds 20 dB. As the set value increases, the measured value shows a flat top phenomenon, and the measured value is stable at 13 dB. The measurement error is getting larger and larger; compared with the prior art, the measurement result obtained by the technical solution of the invention is closer to the true value, and in the range of 0-4040, the measured value is basically the same as the true value. It can be seen that the technical solution of the present invention is better than the prior art. A more accurate carrier-to-interference ratio can be obtained.

As can be seen from the above embodiment, the present invention eliminates the calculated interference noise power by processing the channel response estimation values on multiple adjacent pilot subcarriers of all pilot symbols in one subframe due to the frequency domain channel response. The power error caused by the change of frequency and time overcomes the disadvantages of inaccurate measurement of carrier-to-interference and noise ratio caused by frequency selective fading and time-selective fading of the channel in the prior art, so that the calculated signal power and interference are obtained. The noise power is more accurate, so that the calculated carrier-to-interference and noise ratio is more accurate, which solves the problem that the carrier-to-interference and noise ratio existing in the prior art cannot simultaneously cope with the frequency selective fading and time-selective fading of the channel, thereby achieving sufficient The use of carrier-to-noise-to-noise ratio for adaptive code modulation, power control, and resource allocation improves system performance, and provides the required performance improvements for key algorithms such as channel estimation algorithms and MIMO algorithms involved in MIMO-OFDM systems. Interference noise power or carrier interference Noise ratio parameters can further improve system performance.

While the preferred embodiments of the present invention have been disclosed for purposes of illustration, those skilled in the art will recognize that various modifications, additions and substitutions are possible, and the scope of the invention should not be limited to the embodiments described above.

Claims

Claim

A method for estimating a carrier to interference and noise ratio in an Orthogonal Frequency Division Multiplexing system, the method comprising the steps of:

S103: Obtain an average interference noise power of a pilot symbol in the subframe according to an interference noise item on each group of pilot subcarriers.

5104. Acquire a total average power of pilot symbols in a subframe.

2. The method according to claim 1, wherein the grouping method is: grouping three adjacent pilot subcarriers in each pilot symbol in a subframe as a group.

3. The method according to claim 2, wherein in step S101, obtaining the second-order difference value comprises the following steps:

51012, subtracting the two differences obtained in each group, and the result is the second-order difference value.

The method according to claim 2, wherein in step S102, acquiring the interference noise item comprises the following steps:

51021, dividing the pilot symbols in the subframe into two pairs according to adjacent or spaced apart;

The method according to claim 2, wherein, in step S103, acquiring the average interference noise power of the pilot symbols in the subframe comprises the following steps:

The method according to any one of claims 2 to 5, wherein, in step S101, when three adjacent pilot subcarriers in each pilot symbol in a subframe are grouped as a group, the grouping is performed. The form is:

, ,

Where = 1, 2, 3, 4, ' represents the number of the pilot symbol;

Rounding down, M indicates the number of packets, m indicates the number of each group, and K indicates the number of pilot subcarriers.

The method according to any one of claims 2 to 5, wherein, in step S101, when three adjacent pilot subcarriers in each pilot symbol in the subframe are grouped as a group, the grouping is performed. The form is . H _m , H _{i m+i} , H _{i m+1} · where / = 1,2,3,4 , ^; ' denotes the number of the pilot symbol; = l,2,...,M , Μ = Κ - 2 , Μ indicates the number of packets, m indicates the number of each group, and K indicates the number of pilot subcarriers.

8. An apparatus for estimating a carrier to interference and noise ratio in an Orthogonal Frequency Division Multiplexing system, the apparatus comprising:

a grouping unit, configured to group pilot subcarriers in each pilot symbol in a subframe; a second order difference value acquiring unit, configured to obtain a channel response estimate on each group of pilot subcarriers of each pilot symbol Second-order difference value of the value;

An interference noise item acquiring unit, configured to acquire, according to the second-order difference value, a perturbation noise item on each set of pilot subcarriers of each pilot symbol; An average interference noise power acquiring unit, configured to acquire, according to an interference noise item on each set of pilot subcarriers, an average interference noise power of pilot symbols in the subframe;

The apparatus according to claim 8, wherein the grouping unit is configured to group three adjacent pilot subcarriers in each pilot symbol in a subframe as a group.

The device of claim 9, wherein the second-order difference value acquisition unit comprises:

The device according to claim 8 or 9, wherein the interference noise item obtaining unit comprises:

a pair of sub-units, configured to divide pilot symbols in a subframe into two pairs according to adjacent or spaced apart; an interference noise item acquisition sub-unit, configured to be used on each set of pilot subcarriers in each pair of pilot symbols The second-order difference value of the channel response estimate is subtracted; then the subtraction result obtained by the two pairs of pilot symbols is correspondingly subtracted again, and the result is the interference noise term.

The apparatus according to claim 8 or 9, wherein the average interference noise power acquisition unit comprises: