WO2013075484A1

WO2013075484A1 - Method and device for detecting interference

Info

Publication number: WO2013075484A1
Application number: PCT/CN2012/077502
Authority: WO
Inventors: 侯晓辉
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-11-23
Filing date: 2012-06-26
Publication date: 2013-05-30
Also published as: CN103138856A; CN103138856B

Abstract

A method and a device for detecting interference. The method comprises: performing a channel estimation on a carrier channel to obtain a tap {h̃_j} of an impact response of the carrier channel; calculating an autocorrelation function ρ̃ _H（τ）of the carrier channel according to the tap {h̃_j} of the impact response of the carrier channel; calculating an autocorrelation function ρ̃ _Υ（τ） of a received baseband symbol; calculating an autocorrelation function ρ̃ _G（τ） of interference or noise, wherein ρ̃ _G（τ）=ρ̃ _Υ（τ）-ρ̃ _H（τ）; detecting whether the equation ρ̃ _G（τ）=0 is valid; if ρ̃ _G（τ）=0, determining that no interference exists; if ρ̃ _G（τ） ≠ 0, determining that interference exists.

Description

Method and device for detecting interference

Technical field

The present invention relates to the field of wireless communication technologies, and in particular, to a method and apparatus for detecting interference.

Background technique

In wireless communication, there are two main situations, one is to add Gaussian white noise in the wireless channel, and the other is to add interference in the wireless channel. In order to more accurately equalize and demodulate the wireless signal, different processing methods are usually adopted for the two cases. In other words, for interference limited, interference suppression or interference cancellation is required. Therefore, it is very important to determine whether the wireless signal received by the current receiver is noise-limited or interference-limited before performing the digital baseband equalization demodulation.

Current detection techniques are either based on first-order statistical properties of noise and interference, or based on specific spectral characteristics. The accuracy of these methods is not very high.

Summary of the invention

A technical problem to be solved by embodiments of the present invention is to provide a method and apparatus for detecting interference, which can accurately detect whether a wireless signal has interference.

To solve the above technical problem, a method for detecting interference according to an embodiment of the present invention includes: performing channel estimation on a carrier channel to obtain a tap of a shock response of a carrier channel;

Calculating the autocorrelation function PH of the carrier channel based on the tap j of the impulse response of the carrier channel ( ;

Calculate the autocorrelation function of the received baseband symbol to calculate the autocorrelation function _σ (τ) of interference or noise, p ~ _G (r) = p ~ _y (r) - P _H (r);

Check if _σ ( ) = 0 is true, if = then it is determined that there is no interference; if ρ _ο {τ) ≠ 0, it is determined that there is interference.

Optionally, the tap according to the impact response of the carrier channel is used to calculate the self of the carrier channel. The correlation function ^( , includes: According to (r;> = calculation, the autocorrelation function of the carrier channel (Γ) is obtained, where ^ is the dispersion length of the channel impulse response, τ = 0,···, ^-1 Optionally, the calculating the autocorrelation function of the received baseband symbol comprises: calculating according to _Α , ( ₇ ) = ^ ^_3⁄4 ϋ ^, and obtaining an autocorrelation function of the received baseband symbol.

L _B — k=o

ρ _ν (τ) , where J _s is the number of baseband symbols in a frame, r = 0,... -1, where _Λ is the received baseband symbol.

Optionally, the detecting (7) = 0 whether to calculate the power of the received baseband symbol, where J _s is a baseband in one frame

The number of symbols, _Λ is the received baseband symbol; Calculate _c= k^l, detect according to c^(0=0 is established. Alternatively, the detection according to C; 3⁄4(7) = 0 is true, including :

If C is equal to 0, then it is determined; 3⁄4(7) = 0 is established;

If C is not equal to 0, it is judged whether C is less than /1, and if C is less than /1, it is determined to be noise limited; if C is not less than /1, it is determined that interference is limited.

Optionally, the performing channel estimation on the carrier channel includes:

When there are a plurality of receiving antennas, the signals of the plurality of receiving antennas are combined into one signal, and the combined signals are channel-estimated.

Optionally, an apparatus for detecting interference, comprising: a channel estimation unit, a first calculation unit, a second calculation unit, a third calculation unit, and an interference determination unit, where:

The channel estimation unit is configured to: perform channel estimation on the carrier channel to obtain a tap of the impulse response of the carrier channel; the first calculating unit is configured to: calculate an autocorrelation of the carrier channel according to the tap ftj of the impact response of the carrier channel Function y3⁄4^r);

The second calculating unit is configured to: calculate an autocorrelation function y3⁄4(r) of the received baseband symbol; The third calculation unit is configured to: calculate an autocorrelation function _σ (τ) of interference or noise,

The interference determining unit is configured to: detect; 3⁄4(7)=() is established, if _σ (τ) = 0, it is determined that there is no interference; if (r) ≠ 0, it is determined that there is interference. Optionally, the first calculating unit is configured to: calculate according to (r)= ₊ , and obtain an autocorrelation function ^τ) of the carrier channel, where Z _ff is a dispersion length of the channel impulse response, r = 0 ,… - 1. Optionally, the second calculating unit is configured to:

Calculate, obtain the autocorrelation function of the received baseband symbol, where J _S is the number of baseband symbols in one frame, τ = ο,··· -1, and _Λ is the received baseband symbol.

The interference determining unit is configured to: calculate a power of the received baseband symbol, where ^ is a number of baseband symbols in a frame, and Λ is a received baseband symbol;

Calculate _c= k and check according to c(0 = 0). Alternatively, the interference determining unit is set to:

If C is equal to 0, then it is determined that y3⁄4(r) = 0 is true;

If C is not equal to 0, then it is determined that = is not true, and then it is judged whether C is less than /1. If C is less than 1, it is determined to be noise limited; if C is not less than, it is determined to be interference limited.

Optionally, the channel estimation unit is configured to:

In summary, the calculation method of the embodiment of the present invention is simple, and the probability of missed detection of interference detection is low, and the method of the present invention can accurately detect the existence of interference, thereby whether interference suppression is adopted for digital baseband equalization demodulation. Or the interference cancellation algorithm provides the basis.

BRIEF abstract 1 is a flowchart of a method for detecting interference according to an embodiment of the present invention;

2 is a block diagram of an apparatus for detecting interference according to an embodiment of the present invention. Preferred embodiment of the invention

The channel in the wireless communication system is not an ideal channel, and there are various random fluctuation noises, including atmospheric noise, base noise and impulse noise of electronic equipment, etc. It is also pointed out that due to frequency reuse and other reasons, wireless channels are often Suffering from interference, these independent random noises are represented by random signals and obey the normal distribution, ie Ο Λ^Ο, σ ² ). Therefore, the noise-limited wireless channel model is expressed as: y _k = _J h _J u _k _ _J +e _k (1)

7=0

Where _Λ is the received baseband symbol, is the _/·th tap of the impulse response of the wireless channel, u _k is the transmitted symbol, and J _ff is the dispersion length of the wireless channel impulse response.

The channel model with limited interference is expressed as:

Where M represents the number of interferers, J _ff is the dispersion length of the impulse response of the wireless channel, and is the dispersion length of the impulse response of the channel through which the first interferer passes; for transmitting symbols, ) is initiated from the source of interference The discrete signal form, .s. is the _/·th tap of the wireless channel impulse response, . , j = 0, --, 4 ^m) -1 is the jth tap of the wireless channel corresponding to the mth interferer.

Before the interference suppression, the primary problem to be solved is the detection of the interference signal. If it is determined by the interference detection algorithm that there is no interference, interference suppression or interference cancellation is not required, and if it is determined that interference exists, interference suppression or interference cancellation is performed.

This paper determines whether there is interference based on the cross-correlation of the received signals. This paper presents two opposing devices.

H ₀ : The channel model conforms to equation (1).

Η The _λ channel model conforms to equation (2).

( _Λ ) The cross-correlation function Α(τ) = _Αϊ (τ) ₊ _σσ (τ) ₊ Α(τ), since ^(τ) = ^. σ ² , where S _mn is a Delta function. Therefore, there is no interference in the network, ie H. When it is established, ρ _ο (τ) = ρ _γ (τ) - ρ _Η (τ) = , τ ≠ , therefore, the test method of the present embodiment is to check whether ? _σ (Γ) is 0 to determine whether there is interference. That is, if ? _σ ( ) is not 0, there is interference, and if it is 0, there is no interference.

The method for detecting interference in this embodiment includes:

Step 1: Perform channel estimation on the radio channel (carrier channel) through which the signal source passes, and obtain a tap of the impulse response of the channel through which the signal source passes; the tap of the impulse response of the channel through which the signal source passes may also be referred to as a channel. estimate.

In the present embodiment, the method of channel estimation is not limited, and any existing channel estimation method can be used in the present embodiment.

Step 2: According to the autocorrelation function of the wireless channel through which the signal source passes = ϋ _τ , where τ = 0,··· - 1; Step 3: Calculate the received baseband symbol, where

T = 0, -, L _H -\ ; J _S is the number of baseband symbols in a frame; Step 4: Calculate (0 = ^(0-^(r), check if _σ (τ) = 0 holds.

In this embodiment, it is determined whether ^(7) = 0 is established, and the power of the received baseband symbol can be calculated as =, where ^ is the number of baseband symbols in one frame, and the statistics are utilized.

C=fc is detected. When c is equal to 0, then _σ (τ) = 0 holds; if C is not equal to 0, it is judged whether C is less than, if C is less, it is determined to be noise limited; if C is not less than, then it is determined Limited for interference. The purpose of normalization here is mainly to ensure that the size of the quantile value is not affected by the received power. Here, the specific value of A can be determined empirically, and the specific data of A is not limited in this embodiment.

In actual systems, there are often multiple receiving antennas. In order to detect interference more accurately, the methods of combining and combining the signals of each antenna for maximum ratio combining, equal gain combining, and selective combining can be combined into one signal, and then The detection of this signal can further influence the channel fading and more accurately detect the interference. The present embodiment will be further described in detail below with reference to the accompanying drawings:

Taking the GSM system as an example for further explanation, the wireless channel uses a typical TU50 channel. As shown in FIG. 1, the method for detecting interference in this embodiment includes:

Step 101: The received baseband signal is a channel estimation for calculating a carrier channel (a wireless channel through which the signal source passes) according to channel estimation criteria such as LS, as follows:

Channel estimation, converting the channel estimate to ίι = . ~ ... , get ftj, where T is a matrix consisting of 26 training sequences.}, = 0,..., ²⁵ . Step 102: Calculate an autocorrelation function A^r) of the carrier channel, p _H ( ) = ^LH ∑ h _k hi _T , where

k=0

T = 0, ---, L _H -l ;

The self - correlation function of the symbol , the number of symbols ;

Step 105: Calculate the autocorrelation function _σ (τ) of interference or noise, p _G {T) = p _y {T)-p _H {T); Step 106: Normalize ^τ) to obtain statistics (: , c=^^l, check if C = 0 is true.

When actually making a judgment, if (:<, it is considered to be noise limited; otherwise, it is considered to be interference limited.

As shown in FIG. 2, the apparatus for detecting interference according to this embodiment includes: a channel estimation unit, a first calculation unit, a second calculation unit, a third calculation unit, and an interference determination unit, where:

a channel estimation unit, configured to perform channel estimation on the carrier channel, to obtain a tap of the impact response of the carrier channel;

a first calculation unit, configured to calculate a carrier based on a tap of the impact response of the carrier channel} Channel autocorrelation function ( );

a second calculation unit, configured to calculate an autocorrelation function of the received baseband symbol ^

a third calculation unit, set to calculate an interference or noise autocorrelation function ^(r), Ρο{τ) = Ρ _ν {τ)-ρ _Η {τ);

The interference determining unit is set to detect whether _σ ( ) = () is established, and if _σ ( ) = 0, it is determined that there is no interference; if _σ ( ) ≠ 0, it is determined that there is interference. Preferably, the first calculating unit is configured to perform (r; >= _+T calculation to obtain an autocorrelation function A^ of the carrier channel), wherein J _FF is a dispersion length of the channel impulse response,

T = 0, ---, L _H -l. Preferably, the second calculating unit is configured to perform calculation according to A(r) = ^~ — to obtain an autocorrelation function of the received baseband symbol, where J _S is the number of baseband symbols in one frame, T = 0, -, L _H -\ , _Λ is the received baseband symbol.

The interference determining unit is configured to calculate a power of the received baseband symbol, where ^ is the number of baseband symbols in one frame, and _Λ is the received baseband symbol;

Calculate c=^, detect according to C ^(0 = 0 is true.

Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. The steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps are fabricated as a single integrated circuit module. Thus, the invention is not limited to any particular combination of hardware and software.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

INDUSTRIAL APPLICABILITY The calculation method of the embodiment of the present invention is simple, and the probability of missed detection of interference detection is low. The method described in the embodiment of the present invention can accurately detect the existence of interference, thereby whether interference suppression is adopted for digital baseband equalization demodulation. Or the interference cancellation algorithm provides the basis.

Claims

Claim

1. A method of detecting interference, comprising:

Performing channel estimation on the carrier channel to obtain a tap of the impulse response of the carrier channel; calculating an autocorrelation function PH of the carrier channel according to the tap j of the impulse response of the carrier channel;

Calculate the autocorrelation function A ( ) of the received baseband symbol; calculate the autocorrelation function _σ (τ) of interference or noise, p ~ _G (r) = p ~ _y (r) - P _H (r);

Check if _σ ( ) = () is true, if = then it is determined that there is no interference; if ρ _ο {τ) ≠ 0, it is determined that there is interference.

2. The method according to claim 1, wherein the step of calculating an autocorrelation function of the carrier channel according to the tap of the impulse response of the carrier channel comprises: calculating according to (r) = _+τ , obtaining a carrier channel In the autocorrelation function, where ^ is the dispersion length of the channel impulse response, τ = 0, ···, ^-1.

3. The method according to claim 1, wherein the step of calculating the autocorrelation function ^(7) of the received baseband symbol comprises: calculating according to Α(τ) = ^~ ϋ^ _+Τ , obtaining the received The autocorrelation function p ~ _y (r) of the baseband symbol, where J _s is the number of baseband symbols in a frame, τ = 0, ···, ^-1, where _Λ is the received baseband symbol.

4. The method according to claim 1, wherein the step of detecting (==0 is established: calculating power of the received baseband symbol = ^:, where ^ is a baseband in one frame

The number of symbols, _Λ is the received baseband symbol; Calculate _{c =} k^l, detect according to c (0 = 0 is true.

5. The method according to claim 4, wherein said detecting according to C(^ = 0 is established The steps include:

If C is equal to 0, then it is determined that _σ (7) = 0 holds;

If C is not equal to 0, then it is determined that ^(^ = 0 does not hold, and then it is judged whether C is less than /1, if C is less than 1, it is determined to be noise limited; if C is not less than, it is determined that interference is limited.

6. The method of claim 1, wherein the step of performing channel estimation on a carrier channel comprises:

7. An apparatus for detecting interference, comprising: a channel estimation unit, a first calculation unit, a second calculation unit, a third calculation unit, and an interference determination unit, wherein:

The channel estimation unit is configured to: perform channel estimation on a carrier channel to obtain a tap of an impact response of the carrier channel;

The first calculating unit is configured to: calculate an autocorrelation function (τ) of the carrier channel according to the tap j of the impulse response of the carrier channel;

The second calculating unit is configured to: calculate an autocorrelation function ^(r) of the received baseband symbol; the third calculating unit is configured to: calculate an autocorrelation function of interference or noise (0,

Ρο{τ) = Ρ _ν {τ)-ρ _Η {τ);

The interference determining unit is configured to: detect whether _σ (τ) = 0 holds, if _σ (τ) = 0, it is determined that there is no interference; if ^τ^Ο, it is determined that there is interference.

8. The apparatus according to claim 7, wherein: the first calculating unit is configured to: obtain an autocorrelation function of a carrier channel according to (r; >= f−, wherein J _ff is a channel impulse The dispersion length of the response, T = 0, ---, L _H -l.

9. The apparatus according to claim 7, wherein: the second calculating unit is configured to: calculate according to A(r;>=^~3⁄4 j _T , The autocorrelation function of the received baseband symbol, where J _S is the number of baseband symbols in a frame, T = 0, -, L _H -\ , and _Λ is the received baseband symbol.

10. Apparatus according to claim 7 wherein:

The interference determining unit is configured to: calculate a power of the received baseband symbol,

Where ^ is the number of baseband symbols in a frame, and _Λ is the received baseband symbol;

Calculate _{c =} k^l and check according to c (0 = 0).

11. The apparatus according to claim 10, wherein the interference determining unit is configured to: if C is equal to 0, determine that _σ (τ) = 0 is established;

If C is not equal to 0, then it is determined that ^(^ = 0 does not hold, and then it is judged whether C is smaller or smaller, if C is smaller, it is determined to be noise limited; if C is not smaller, it is determined that interference is limited.

The device according to claim 7, wherein the channel estimation unit is configured to: when there are multiple receiving antennas, synthesize signals of the plurality of receiving antennas into one signal, and combine the obtained one signals Perform channel estimation.