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Multipath time delay and Doppler frequency shift estimation method in signal channel based on fractional Fourier transform and system for implementing method

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

Inactive Publication Date: 2010-02-10
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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  • Multipath time delay and Doppler frequency shift estimation method in signal channel based on fractional Fourier transform and system for implementing method
  • Multipath time delay and Doppler frequency shift estimation method in signal channel based on fractional Fourier transform and system for implementing method
  • Multipath time delay and Doppler frequency shift estimation method in signal channel based on fractional Fourier transform and system for implementing 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 finished 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 obt...

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 implementation mode three, the difference between this specific implementation mode and specific implementation mode one is that N=3, that is, it detects the position of the correlation peak on the fractional field of three different orders, establishes three equations, and then three The time delay estimates obtained by solving the two equations respectively, and the Doppler frequency shift estimates are averaged to obtain the final estimation results. 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 accord...

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Abstract

The invention discloses a multipath time delay and Doppler frequency shift estimation method in a signal channel based on fractional Fourier transform and a system for implementing the method, and relates to a signal channel estimation method and the system. The method and the system can solve the problem that the existing Doppler frequency shift and multipath time delay estimation in the signal channel adopts the statistical assumption method, thereby resulting in low estimation accuracy. The method is as follows: a chirp signal produced by a transmitting node produces a signal channel estimation signal after modulating a training sequence and transmits to the signal channel; a target node receives the signal, then filtration and sampling are carried out, sampling values are divided intoN parallel paths, the fractional Fourier transform with the different order is respectively carried out on each path, then the correlation calculation is carried out with a local reference signal, theposition of a peak value of each path is detected, and the multipath time delay and the Doppler frequency shift are estimated according to the positions of the peak values. The device uses N fractional domain modules for calculating the sampling values and adopts a multipath time delay and Doppler frequency shift combined estimation module for estimating the multipath time delay and the Doppler frequency shift. The method and the system are applicable to the performance improvement process of a 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. like 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 th...

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Application Information

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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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