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Anti-large-frequency-offset LTE (Long Term Evolution) downlink initial time synchronizing method

A technology of initial time and frequency offset, applied in the field of downlink initial time synchronization, which can solve the problems of inaccurate synchronization, increased receiver cost, system performance impact, etc.

Active Publication Date: 2011-09-28
MSTAR SEMICON INC
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  • Abstract
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  • Application Information

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Problems solved by technology

In this case, if a matched filter is used to match the PSS, the distance between the matching peak position and the correct PSS start position will be greater than the length of the CP, and inaccurate synchronization will have a great impact on system performance
In the prior art, it is assumed that the initial frequency deviation of the crystal oscillator will not be greater than ±5ppm, which undoubtedly increases the cost of the receiver

Method used

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  • Anti-large-frequency-offset LTE (Long Term Evolution) downlink initial time synchronizing method
  • Anti-large-frequency-offset LTE (Long Term Evolution) downlink initial time synchronizing method
  • Anti-large-frequency-offset LTE (Long Term Evolution) downlink initial time synchronizing method

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Embodiment Construction

[0045] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings.

[0046] Such as figure 2 As shown, first receive 5ms half-frame data and several trailing sampling data, low-pass filter and down-sample the received data. The purpose of down-sampling is to reduce the calculation amount of initial synchronization. The length of the data to be processed after down-sampling is set to be N f , the SSS symbol length is N s , set the threshold T, 0 That is, the starting position of the SSS symbol in the field, such as image 3 shown.

[0047] θ ^ = arg max θ ( | Σ n ...

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Abstract

The invention discloses an anti-large-frequency-offset LTE (Long Term Evolution) downlink initial time synchronizing method. The method comprises the following steps of: receiving field data and a plurality of trailing sampled data; performing low-pass filtering and down sampling on the received data to obtain data needing to be processed after down sampling, wherein the length of each datum is Nf and the length of a symbol SSS is Ns; setting a threshold value T, wherein T is more than 0 and less than or equal to 1; performing reverse moving correlation on the field data and the trailing dataaccording to a formula to obtain the start position of the symbol SSS in a field; after the start position of SSS is found, finding the start position of a corresponding symbol PSS according to four assumptions, i.e., TDD / ordinary CP, TDD / expansion CP, FDD / ordinary CP and FDD / expansion CP; extracting subsequent Np sampling points serving as receiving time domain symbols PSS from the start position of the PSS; and setting four time domain symbols PSS corresponding to four assumption types as r1(n), r2(n), r3(n) and r4(n) for performing frequency sweeping matching of PSS.

Description

technical field [0001] The present invention relates to the technical field of mobile communication, in particular to a downlink initial time synchronization method against large frequency deviation in a long term evolution (Long Term Evolution, LTE) system. Background technique [0002] LTE (Long Term Evolution, long-term evolution) is 3GPP (3 rd Generation Partnership Project, the 3rd Generation Partnership Project) the next generation of wireless communication technology developed. It can reach the transmission rate of 100Mbit / s in the downlink and 50Mbit / s in the uplink. The downlink of the LTE system adopts OFDM (Orthogonal Frequency Division Multiplexing) technology, which enhances the spectrum utilization rate. The length of a downlink wireless frame is 10ms, which is divided into 10 subframes with a length of 1ms. Each subframe It can also be divided into 14 OFDM symbols or 12 OFDM symbols according to the length of the adopted CP (Cyclic Prefix, cyclic prefix). ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26
Inventor 孙飞雪
Owner MSTAR SEMICON INC
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