Method for self-interference multipath channel estimation of simultaneous full-duplex based on zero-correlation zone sequence

Abstract

The application discloses a method for self-interference multipath channel estimation based on zero correlation zone sequence. The method comprises the following steps: in the channel estimation stage of the simultaneous full duplex communication, a zero correlation zone sequence is sent; by using the good autocorrelation and cross-correlation characteristics of the zero correlation zone sequence, the receiver uses the same zero correlation zone sequence to slide correlate with the received signal, and the self-interference multipath channel can be accurately decomposed into several single-path channels; and the single-path channel parameters are estimated by using the correlation peak and the known zero correlation zone sequence. The application can more accurately estimate the self-interference multipath channel parameters, and ensures the self-interference cancellation ability in the multipath environment.

Description

TECHNICAL FIELD

[0001] The present application relates to a self-interference cancellation method in simultaneous full-duplex communication, in particular to a self-interference multipath channel estimation method using zero-correlation zone sequence, and belongs to the field of wireless communication. BACKGROUND

[0002] Simultaneous full-duplex communication is a technology that transmits and receives in the same time slot and the same frequency point, and extracts the useful signal in the received signal through self-interference cancellation technology. In theory, the self-interference is completely cancelled to achieve double spectral efficiency. The self-interference cancellation technology includes spatial domain transmit-receive antenna isolation, analog domain and digital domain subtraction of reconstructed self-interference signal. When reconstructing the self-interference signal in the analog domain and the digital domain, whether the self-interference channel parameter estimation is accurate determines the self-interference cancellation capability. Generally, a known pseudo-random sequence is sent before the formal communication starts to estimate the channel parameters. However, the transmitted self-interference signal will generally pass through a multipath channel to reach the receiving end, and the low signal-to-noise ratio or the non-ideal correlation characteristics of the pseudo-random sequence make it difficult to accurately estimate the self-interference multipath channel using this method. SUMMARY

[0003] In order to accurately estimate the self-interference multipath channel and achieve efficient self-interference cancellation, the present application proposes a method of accurately decomposing the multipath channel into several single-path channels using a zero-correlation zone sequence, estimating the parameters of the single-path channel using the correlation peak, and then realizing self-interference multipath channel estimation.

[0004] The technical solution of the present application is as follows:

[0005] A simultaneous full-duplex self-interference multipath channel estimation method, comprising the following steps:

[0006] 1) The full-duplex transmitter transmits a zero-correlation zone sequence, and the autocorrelation of the zero-correlation zone sequence in the zero-correlation zone has only one correlation peak when perfectly aligned, and the autocorrelation of other points is strictly 0; the cross-correlation in the zero-correlation zone is strictly 0;

[0007] 2) The zero-correlation zone sequence enters the full-duplex receiver after passing through the multipath channel, and the received zero-correlation zone sequence after passing through the multipath channel is represented as

[0008]

[0009]

[0010] Wherein, the multipath channel can be decomposed into N single-path channels, and h i is the impulse response of the i-th single-path channel; represents the received signal after the transmitted sequence passes through the i-th single-path channel with a time delay τ i ; the transmitted signal with time delay τ i , where k is the length of the zero correlation zone sequence.

[0011] 3) The receiver uses the same locally saved zero correlation zone sequence to slide correlate with the received zero correlation zone sequence y, denoted as

[0012]

[0013] where is the transmitted signal with time delay τ, when τ = τ i , the correlation result R τ = h i ||x τ || 2 + x τ n i , where the sequence x τ is independent of the noise n i , so R τ ≈ h i ||x τ || 2 will have a correlation peak; when τ ≠ τ i , the correlation result R τ = x τ n i ≈ 0, without a correlation peak.

[0014] 4) The full-duplex receiver detects the correlation peaks in the sliding correlation result of step 3), and each correlation peak represents a single path. The time delay τ i of the i-th single path is obtained from the time delay τ i of the i-th correlation peak, and is calculated as where is the value of the correlation peak with time delay τ i , is the modulus square of the transmitted zero correlation zone sequence with time delay τ i , and h i is the impulse response of the i-th single path. At this point, the time delay and impulse response of the i-th single path are calculated. Similarly, the time delay and impulse response of each single path can be calculated, and the multi-path channel is decomposed into several single-path channels.

[0015] The present application uses the good autocorrelation and cross-correlation characteristics of the zero correlation zone sequence to accurately decompose the multi-path channel into several single-path channels, and improves the accuracy of the self-interference channel estimation in a multi-path environment. Compared with the method of using a traditional pseudo-random sequence to estimate the channel parameters, the present application avoids the estimation error caused by the non-ideal correlation characteristics of the sequence. The self-interference cancellation capability is ensured without improving the complexity of the system design. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram showing the simulation results of the self-interference multipath channel estimation error in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below by way of examples in conjunction with the accompanying drawings, but the scope of the present invention is not limited in any way.

[0018] When performing self-interference channel estimation, the zero correlation zone sequence is completely known to the local receiver. The present invention provides a method for estimating a co-frequency simultaneous full-duplex self-interference multipath channel based on the zero correlation zone sequence, the steps of which include:

[0019] Before formal communication begins, the full-duplex transmitter transmits a zero-correlation zone sequence for channel estimation. The zero-correlation zone sequence consists of k = 100 symbols, with a length of five symbol periods. The autocorrelation of the zero-correlation zone sequence within the zero-correlation zone has a peak only when perfectly aligned; the autocorrelation at all other points is strictly zero. The cross-correlation is strictly zero within the zero-correlation zone. The zero-correlation zone sequence can be transmitted independently or inserted at the beginning of a communication frame along with useful data.

[0020] 2. After the zero correlation zone sequence passes through the multipath channel and enters the full-duplex receiver, the zero correlation zone sequence received through the multipath channel can be expressed as

[0021]

[0022]

[0023] Among them, the multipath channel can be decomposed into N = 3 single-path channels, h i is the impulse response of the ith single-path channel, which obeys a complex Gaussian distribution with zero mean and variance 1, and the maximum delay of a single path does not exceed 5 symbol periods; Indicates that the transmission sequence has a delay of τ after the i-th i The received signal after the single-path channel; is the time delay τ i The transmission signal, is the Gaussian white noise of the i-th single-path channel, where k is the length of the zero correlation zone sequence.

[0024] The receiver uses the same zero correlation zone sequence stored locally to perform sliding correlation with the received zero correlation zone sequence y, which can be expressed as

[0025]

[0026] in, is the transmitted signal with a time delay of τ, when τ=τ iWhen the relevant result R τ =h i ||x τ || 2 +x τ n i , where the sequence x τ With noise n i are independent of each other, so R τ ≈h i ||x τ || 2 , there will be a correlation peak; when τ≠τ i When the relevant result R τ =x τ n i ≈0, no correlation peak.

[0027] 3. The full-duplex receiver detects the correlation peaks in the sliding correlation results. Each correlation peak represents a single path. The time delay τ passing the i-th correlation peak is i The delay of the i-th single path is τ i , and calculate in The time delay is τ i The value of the correlation peak, is the time delay τ i The transmitted zero correlation zone sequence Calculate the square of the modulus, h i is the impulse response of the i-th single path. At this point, the delay and impulse response of the i-th single path are calculated. Similarly, the delay and impulse response of each single path can be calculated to decompose the multipath channel into several single-path channels.

[0028] 4. When formal communication begins, the receiver reconstructs the self-interference signal based on the calculated delays and impulse responses of all single paths, and subtracts the reconstructed self-interference signal from the received signal to achieve self-interference cancellation.

[0029] The specific embodiment of the present invention was simulated and analyzed in MATLAB simulation software, and the curve of channel estimation error changing with signal-to-noise ratio is shown in FIG. Figure 1 As shown, it can be seen that the error of the self-interference multipath channel estimation using the zero correlation zone sequence of the present invention is lower than the error of the self-interference multipath channel estimation using the traditional pseudo-random sequence, and the estimation error of the present invention can approach 0 as the signal-to-noise ratio increases.

[0030] It is to be understood that the embodiments which have been described are merely illustrative of the principles of this application and that numerous and various modifications can be made by those skilled in the art without departing from the spirit and scope of the application as disclosed in the specification and the appended claims. The application is not limited to the embodiments disclosed, but is intended to cover any adaptations or modifications of this application. The scope of the application is limited only by the claims.

Claims

1. A method for self-interference multipath channel estimation in simultaneous full-duplex, comprising the following steps: 1) A zero-correlation zone sequence is transmitted by a full-duplex transmitter, the self-correlation of the zero-correlation zone sequence in the zero-correlation zone has only one correlation peak when perfectly aligned, and the self-correlation of other points is 0; the cross-correlation in the zero-correlation zone is 0; 2) After passing through a multipath channel, the zero-correlation zone sequence enters a full-duplex receiver, and the received zero-correlation zone sequence passing through the multipath channel is represented as y = ∑h k x k + n wherein The multipath channel is decomposed into N single-path channels, h i is the impulse response of the i-th single-path channel; is the received signal after the zero correlation zone sequence passes through the i-th single-path channel with a time delay of τ i is the received signal after the zero correlation zone sequence passes through the i-th single-path channel with a time delay of τ is the zero correlation zone sequence with a time delay of τ i is the zero correlation zone sequence with a time delay of τ is the Gaussian white noise of the i-th single-path channel, where k is the length of the zero correlation zone sequence; 3) The receiver uses a locally saved same zero-correlation zone sequence to perform a sliding correlation with the received zero-correlation zone sequence y, represented as where is the zero correlation zone sequence of the delay τ, when τ = τ i , the correlation result R τ = h i ‖x τ ‖ 2 +x τ n i , where the sequence x τ is independent of the noise n i , so R τ ≈ h i ‖x τ ‖ 2 , there will be a correlation peak; when τ ≠ τ i , the correlation result R τ = x τ n i ≈ 0, there is no correlation peak; 4) Full-duplex receiver detection step 3) The correlation peaks in the sliding correlation result, each correlation peak represents a single path, and the delay τ passing through the i-th correlation peak i The delay of the i-th single path is τ i , and calculate in The time delay is τ i The value of the correlation peak, is the time delay τ i Zero correlation zone sequence Calculate the square of the modulus, h i is the impulse response of the ith single path, and the delay and impulse response of each single path channel are calculated.

2. The method of claim 1, wherein, In step 1), the zero-correlation zone sequence transmission is performed by separate transmission or insertion into the beginning of a communication frame together with useful data.

3. The method of claim 1, wherein, The maximum time delay of a plurality of single-path channels decomposed from the multipath channel does not exceed the zero-correlation zone length of the zero-correlation zone sequence.

4. The method of claim 1, wherein, After the formal communication starts, the time delay and impulse response of each single-path channel calculated in step 4) are used to reconstruct a self-interference signal, and the reconstructed self-interference signal is subtracted from the received signal.

Images