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Method for estimating and compensating doppler frequency offset in Rician channels in high-speed mobile environment
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A technology of Doppler frequency deviation and high-speed movement, which is applied in the direction of multi-frequency code system and baseband system components, etc., and can solve the problems of smaller, more drastic changes in scattering components, and loss
Inactive Publication Date: 2012-04-04
XIDIAN UNIV
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[0035] 2) Non-optimal frequency offset compensation
from image 3 It can be seen that the SIR in the received signal will become smaller after the received signal is directly compensated by the estimated frequency offset value. This is because the LOS component and the scattering component in the Ricean channel have different frequency offset values. If the LOS component is completely eliminated The frequency deviation above will lead to more drastic changes in the scattering component, which will cause greater interference
In addition, the SIR of the system after frequency offset compensation has more dB loss than the SIR without frequency offset
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Embodiment 1
[0105] Embodiment 1, from the perspective of the frequency domain, the channel estimation in the time domain is obtained:
[0106] Step 1, extract the OFDM / OFDMA pilot symbols in the received signal in the frequency domain, and use the pilot symbols in the received signal and the pilot symbols in the transmitted signal for channel Estimated to obtain the pilot position frequency domain channel response: In the formula, m p is the identity with pilot symbols, k p is the identity of the pilot subcarrier position, Y(m p , k p ) is the position (m p , k p The received signal in the frequency domain at ), X(m p , k p ) is the position (m p , k p ) at the frequency-domain transmitted signal.
[0107] Step 2, the frequency domain channel response to the pilot position Interpolate to get the channel frequency domain response on other data subcarriers on the entire pilot symbol The interpolation algorithm here can use any of linear interpolation, Gaussian interpolation a...
Embodiment 2
[0131] Embodiment 2, from the perspective of the time domain, the channel estimation in the time domain is obtained:
[0132] Step A, construct the frequency domain transmission matrix: X P =diag(X(m p , k 1 ), X(m p , k 2 ),…, X(m p , k p )), where m p is the identity with pilot symbols, k p is the identity of the pilot subcarrier position, X(m p , k p ) is the position (m p , k p ) at the frequency-domain transmitted signal, diag() represents the diagonal matrix notation.
[0133] Step B, send the matrix X by the frequency domain P Build an intermediate data matrix: A P =X P BF k M, where, F k is the N×N unit discrete-time Fourier transform matrix, N is the length of the Fourier transform, M is the N×Q mapping matrix, M = E F , E is a Q×Q unit matrix, Q is the maximum multipath extension of the time-domain...
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Abstract
The invention discloses a method for estimating and compensating doppler frequency offset in Rician channels in a high-speed mobile environment, which mainly solves the problem that the estimation precision of the doppler frequency offset is not high and the problem of non best multiple compensation, comprising the following steps: firstly obtaining a time domain channel estimation by receiving signals through frequency domain channel estimationalgorithm or time domain channel estimation algorithm; extracting the paths which have LOS component from the time domain channel estimation; obtaining the frequency offset estimation value with high precision through executing the frequency offset estimation by using the paths with the LOS component, and determining the best frequency offset compensation multiple through the signal to interference ratio of the maximal receiving signal; finally executing the best frequency offset compensation for the receiving signal, and removing the influence of the doppler frequency offset in the receiving signal. The invention effectively reduces the system performance loss caused by the doppler frequency offset, and can be used for improving the robustness of the doppler frequency offset applied by the OFDM / OFDMA (Orthogonal Frequency Division Multiplexing / Orthogonal Frequency Division Multiple Access) system.
Description
technical field [0001] The present invention belongs to the field of communication, relates to OFDM / OFDMA system of Orthogonal Frequency Division Multiplexing / Orthogonal Frequency Division Multiple Access, in particular to a high-precision Doppler frequency offset estimation and The compensation method can be used to reduce the system performance loss caused by Doppler frequency offset. Background technique [0002] With the continuous construction, opening and use of high-speed railways and expressways, the new generation of mobile communication systems needs to carry out high-speed information transmission with high-speed mobile users. Compared with communication in a static state or a low-speed state, high-speed information transmission in a high-speed mobile state will face more difficulties. In a high-speed mobile environment, since the mobile terminal has a high moving speed, this will introduce a large Doppler frequency shift. The wireless propagation environment of...
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