New OFDM time, frequency synchronization method

A frequency synchronization and time synchronization technology, applied in synchronization devices, multi-carrier systems, digital transmission systems, etc., can solve the problems of low energy efficiency of transmitted data, insignificant peak correlation at the receiving end, and decreased data transmission efficiency, and achieve easy time Synchronized with frequency, excellent performance, and the effect of improving energy efficiency

Inactive Publication Date: 2004-05-05
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Problems solved by technology

[0015] However, the above-mentioned OFDM guard interval design methods have shortcomings. The disadvantage of method (1) is that the correlation peak at the receiving end is not obvious, and the range of its frequency offset estimation is only 1 / 2 of the OFDM system subcarrier spacing.
The disadvantage of method (2) is that the training sequence and OFDM raw data are in the form of time division (or frequency division) multiplexing, resulting in a decrease in data transmission efficiency; in addition, when the position of the training sequence is image 3 will degrade the performance of channel estimation when shown in
The disadvantage of method (3) is that the training sequence interferes too much with the data, and the energy efficiency of transmitting data is low

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  • New OFDM time, frequency synchronization method
  • New OFDM time, frequency synchronization method
  • New OFDM time, frequency synchronization method

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[0069] The implementation steps of this patent under a specific OFDM configuration are given below. It should be noted that the parameters in the following examples do not affect the generality of this patent.

[0070] Let the OFDM useful symbol length be N=4096, and the guard interval length be N g =512. Taking ρ=0.5 means that the energy of the training sequence in the guard interval accounts for 50% of the total energy. The PN sequence is selected as the period N PN = 31 m-sequence, denoted as PN[i]i∈[0, 30], then the number of repetitions of m-sequence in the training sequence is L=N g / N PN =512 / 31=17.

[0071] The transmitter repeats the m-sequence 17 times in a row according to Formula 4 (the last m-sequence will be truncated) to form a training sequence, and performs point-to-point weighted superposition with the original OFDM data according to Formula 5 before transmitting it.

[0072] The receiving end first performs rough time synchronization according to Form...

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Abstract

Weighted addition in point to point between data at back Ng points in OFDM original data and training sequence at transmitting end of OFDM system constitutes guard gap. OFDM original data is unchanged. Fusion algorithm is utilized in the receiving end of OFDM system. Correlativity between data in guard gap and data at back Ng points in OFDM original data as well as correlativity induced by the training sequence are utilized synthetically to process the received data for realizing time and frequency synchronism. The invention makes OFDM system possess good synchronous performance as well as has advantages of small interference on data caused by training sequence.

Description

technical field [0001] The invention belongs to the field of wireless communication or wired communication, and particularly relates to the time-frequency synchronization technology in the OFDM system. Background technique [0002] OFDM has attracted more and more attention due to its high data transmission rate, strong anti-multipath interference ability, and high spectrum efficiency. It has been successfully used in wired and wireless communications. Such as: DAB (Digital Audio Broadcasting), DVB, EEE802.11a and HyperLAN / 2, in the IEEE802.16 that is currently being formulated, OFDM technology is also involved in a large number. OFDM, a new modulation technology, can also be used in a new generation of mobile communication systems. The use of OFDM technology will greatly improve the transmission data rate and spectrum efficiency of the new generation of mobile communication systems, and has a good ability to resist multipath, co-channel interference and impact noise, see ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04J11/00H04L7/00H04L27/32
Inventor 唐友喜严春林房家奕李少谦
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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