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A time advance adjustment method and device for OFDM symbol timing

A technology of time advance and symbol timing, which is applied in the direction of multi-frequency code system, etc., can solve the problems of BER drop, unfavorable, and reduce the accuracy of channel estimation, and achieve the effect of reducing phase rotation and improving accuracy

Inactive Publication Date: 2011-09-21
FUJITSU LTD
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  • Description
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Problems solved by technology

But too much time advance will cause phase rotation on each subcarrier on each OFDM symbol, which is unfavorable for channel estimation using frequency correlation
Too much time advance will reduce the accuracy of channel estimation and cause BER to drop

Method used

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  • A time advance adjustment method and device for OFDM symbol timing
  • A time advance adjustment method and device for OFDM symbol timing
  • A time advance adjustment method and device for OFDM symbol timing

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Embodiment Construction

[0027] The specific implementation manner of the present invention will be described below in conjunction with the accompanying drawings. The present invention describes a device and method for determining OFDM frame / symbol time advance. According to the average phase difference between adjacent subcarriers obtained by channel estimation, the method can adaptively adjust the timing advance. Such as figure 2 As shown, the specific steps of the method are: receiving OFDM signals, performing channel estimation in the frequency domain, calculating the average phase difference between adjacent subcarriers, determining whether the current frame / symbol timing is in the CP or not in the CP, and counting the above events The probability of occurrence; the current frame / symbol timing is in the CP and the probability of not being in the CP is compared with the threshold value, if the threshold value is reached then adjust the timing advance (turn down or increase the timing advance of ...

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Abstract

The invention provides a timing advance regulating method for OFDM symbol timing and a device, the method comprising the steps of: receiving an OFDM signal emitted by a transmitting terminal at a receiving terminal; according to channel frequency domain response message output by channel estimation, judging whether time of current OFDM symbol timing being in cycle prefix length of the OFDM symbolis more than a first preset threshold; if yes, turning down the timing advance of next OFDM symbol timing; judging whether time of current OFDM symbol timing not being in the cycle prefix length of the OFDM symbol is more than a second preset threshold; if yes, turning up the timing advance of next OFDM symbol timing; the method is capable of regulating timing advance self-adaptively.

Description

technical field [0001] The present invention relates to Orthogonal Frequency Division Multiplexing (OFDM) technology, in particular to the reception of OFDM symbols, in particular to a method and device for adjusting the timing advance of OFDM symbol timing. Background technique [0002] Orthogonal Frequency Division Multiplexing (OFDM: Orthogonal Frequency Division Multiplex) is a multi-carrier modulation method that divides the entire channel into many narrow parallel sub-channels, increases the symbol period, and reduces the ISI caused by the multipath environment. Its basic principle is to divide the signal into N sub-signals, and then use the N sub-signals to modulate N mutually orthogonal sub-carriers respectively. Since the frequency spectrums of the subcarriers overlap with each other, higher frequency spectrum efficiency can be obtained. OFDM has been widely used in the field of wireless communication in recent years. [0003] Figure 1a is the working principle o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26
Inventor 周建民孙刚
Owner FUJITSU LTD
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