Method for Estimating Multipath Time Delay and Doppler Frequency Shift in Channel Based on Fractional Fourier Transform and System for Realizing the Method

A fractional Fourier and Doppler frequency shift technology, applied in the field of channel estimation, can solve the problems of poor performance and low estimation accuracy of wireless communication systems, and achieve the effects of high accuracy, improved performance, and good energy aggregation characteristics

Inactive Publication Date: 2011-12-28
HARBIN INST OF TECH
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Problems solved by technology

[0005] The present invention aims to solve the problem that the estimation accuracy of the existing Doppler frequency shift and multipath time delay of the high-speed mobile communication channel is low due to the method of statistical assumption, thus resulting in poor performance of the wireless communication system, thus proposing A method for estimating multipath time delay and Doppler frequency shift in a channel based on fractional Fourier transform and a system for realizing the method

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  • Method for Estimating Multipath Time Delay and Doppler Frequency Shift in Channel Based on Fractional Fourier Transform and System for Realizing the Method
  • Method for Estimating Multipath Time Delay and Doppler Frequency Shift in Channel Based on Fractional Fourier Transform and System for Realizing the Method
  • Method for Estimating Multipath Time Delay and Doppler Frequency Shift in Channel Based on Fractional Fourier Transform and System for Realizing the Method

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specific Embodiment approach 1

[0025] The specific embodiment one, multipath time delay and Doppler frequency shift estimation method in the channel based on Fractional Fourier Transform, it is completed by the following steps:

[0026] Step 1, the chip signal generated by the transmitting node modulates the training sequence to generate a channel estimation signal;

[0027] Step 2, the transmitting node controls and transmits the channel estimation signal;

[0028] Step 3: The target node receives the channel estimation signal described in step 2, and filters the channel estimation signal to obtain a filtered signal;

[0029] Step 4, performing discrete sampling on the filtered signal described in step 3 to obtain a discrete sampling value r(t);

[0030] Step 5, divide the discrete sampling value r(t) described in step 4 into parallel N paths, perform fractional Fourier transforms of different orders on the N paths, and obtain N transformed results r pi (u);

[0031] Step 6. The N transformed results ob...

specific Embodiment approach 2

[0055] Specific implementation mode 2. This implementation mode uses the estimation of a certain path among multiple path signals as an example to illustrate the specific implementation method of the present invention, wherein N=2, and the specific process is:

[0056] Step 1, the chip signal generated by the transmitting node modulates the training sequence to generate a channel estimation signal;

[0057] In this embodiment, a segment of chip signal c(t) is generated according to the channel parameter requirements for channel estimation. The expression of c(t) is shown in formula (2). According to the duration of the chip signal as T and the relationship between the frequency modulation parameter k and the occupied bandwidth of the chip signal: B=kT, select appropriate values ​​of k and T to satisfy the bandwidth allocated by the system for the channel estimation signal.

[0058] Step 2, the transmitting node controls and transmits the channel estimation signal;

[0059] S...

specific Embodiment approach 3

[0073] Specific embodiment three, the difference between this specific embodiment and specific embodiment one is that N=3, that is, it detects the position of the correlation peak on the fractional domain of three different orders, establishes three equation groups, and then three The time delay estimation obtained by solving the equation group separately, and the Doppler frequency shift estimation are averaged to obtain the final estimation result. The method of averaging multiple domains can reduce the error and improve the accuracy of estimation. This section is used to explain how to average the results of multiple fractional Fourier transform domains to obtain channel estimation results.

[0074] It is achieved by the following steps:

[0075] Step 1, the chip signal generated by the transmitting node modulates the training sequence to generate a channel estimation signal;

[0076] In this embodiment, a segment of chip signal c(t) is generated according to the channel p...

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Abstract

A method for estimating multipath time delay and Doppler frequency shift in a channel based on fractional Fourier transform and a system for realizing the method relate to a channel estimation method and system. It solves the problem that the estimation accuracy of Doppler frequency shift and multipath time delay in the existing channel is low due to the statistical hypothesis method. The method is as follows: the chip signal generated by the transmitting node modulates the training sequence to generate a channel estimation signal and transmits it to the channel; the target node receives and filters, samples and divides the sampled values ​​into parallel N paths, and performs different orders for each path After the fractional Fourier transform, the correlation operation is performed with the local reference signal, the peak position of each channel is detected, and the multipath time delay and Doppler frequency shift are estimated according to the peak position. The device uses N fractional domain modules to operate on sampled values, and uses a joint estimation module of multipath time delay and Doppler frequency shift to estimate multipath time delay and Doppler frequency shift. The invention is applicable to the performance improvement process of the wireless communication system.

Description

technical field [0001] The present invention relates to a channel estimation method and its system, in particular to a method and its system for simultaneously estimating signal time delay and Doppler frequency shift by using fractional Fourier transform. Background technique [0002] With the rapid development of wireless communication technology, people have higher and higher requirements for its mobility and data rate. In a high-speed mobile environment, due to the reflection and refraction of surrounding objects, the radio signal arriving at the receiving end is a composite signal from multiple paths in different directions. Such as figure 1 As shown, because the movement of the transmitting and receiving parties will cause the Doppler frequency shift of the signal arriving at the receiving end, the arrival angle θ1 and θ2 of each path are different, and the Doppler frequency shift is also different. And because the length of each path is different, the arrival time of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26H04L25/03
Inventor 沙学军宁晓燕梅林迟永钢吴宣利吴晓涛吴少川
Owner HARBIN INST OF TECH
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