Method and device for determining the starting position of ofdm code element
A technology of starting position and symbol, applied in the field of wireless broadcast communication, can solve the problems of OFDM symbol timing error, inability to offset the influence of crosstalk between symbols, weakened correlation, etc. the effect of reducing the likelihood of
Active Publication Date: 2012-02-08
TSINGHUA UNIV
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[0006] Since in the prior art, only one correlation peak is used to determine the starting position of the OFDM symbol, when the channel condition is poor, under the influence of channel noise, multipath delay, and Doppler frequency shift, the cyclic prefix and the useful The correlation of the L points after the data part is weakened, resulting in no correlation peak at the position where the local correlation peak should appear, and the local correlation peak does appear at other positions with large deviations, resulting in a large error in OFDM symbol timing
At the same time, the existing technology solves the correlation value through the maximum likelihood correlation operation, ignoring the fact that the correlation degree of the cyclic prefix caused by the front and rear symbol crosstalk and the L points after the useful data part are different, and giving the relevant items equal weights, Unable to counteract the influence of inter-symbol crosstalk on correlation calculations
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[0026] In order to solve the problem that the correlation algorithm adopted in the prior art cannot offset the influence of inter-symbol crosstalk on the correlation calculation due to the equal weight given to the related items, the correlation step of the method can use a linear weighted correlation operation to solve the correlation value.
[0027] The present invention also provides a device for determining the initial position of the OFDM symbol, said device comprising: a correlation module, used to calculate the correlation value sequence, and take the θ position as the starting point to open two windows with a length of L and an interval of N, Carry out correlation calculations on the data in the window, and calculate the correlation value obtained at each increment in turn as the θ position increases by 1, so as to obtain the correlation value sequence; the selection module takes the length of N+L as an interval, and in the Select a local correlation peak in each N+L lo...
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The method for determining the starting position of an OFDM symbol belongs to the technical field of determining the starting position of an Orthogonal Frequency Division Multiplexing symbol during wireless broadcast communication. It is characterized in that a linear weighting method is used to calculate the correlation value sequence between the data points in the OFDM symbol cyclic prefix and the corresponding copied data points, and then the effective data length N and the window length L in the correlation value sequence are combined Local correlation peaks and their positions are determined in each interval. Finally, the starting position of the OFDM symbol is determined according to the number of times the difference between the distance between adjacent local correlation peaks and the difference between N+L is less than a certain threshold. The invention has the advantages of high reliability, small symbol timing error, and the ability to offset the influence of crosstalk between some symbols on correlation value calculation and the like.
Description
technical field [0001] The present invention relates to the field of wireless broadcast communication, in particular to a method and a device for determining the initial position of an Orthogonal Frequency Division Multiplexing (OFDM) symbol in the field of wireless broadcast communication. Background technique [0002] As an advanced communication technology, Orthogonal Frequency Division Multiplexing (OFDM) is a research hotspot. It can not only effectively resist channel frequency selective fading, but also greatly improve spectrum utilization. Rate and data rate, is one of the ideal options to achieve high transmission bandwidth. After serial-to-parallel conversion, OFDM converts serial data into parallel data, and then modulates the parallel data onto orthogonal subcarriers, and these modulated orthogonal subcarriers are converted to the time domain by inverse Fourier transform to obtain OFDM symbols. data part. Assuming that the length of the useful data part of the ...
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IPC IPC(8): H04L27/26
Inventor 杨华中曾琳徐淑正
Owner TSINGHUA UNIV