Method of implementing multi-input multi-output orthogonal frequency division multiplexing system time synchronization

Abstract

The invention discloses a time synchronous method of implementing multiple-input and multiple-output orthogonal frequency division multiplexing (OFDM) system, which includes that: a sending end constructs pilot or synchronous symbols in the process of assembling frames. After framing, the antennas launch symbols and simultaneously launch a lead code with a special structure. The lead code is a repeated reference signal, preceding CP. The invention makes use of reference signals and receiving signals to achieve sliding correlation, sets threshold, and records the size and position of amplitudevalue belonging to correlation value exceeding the threshold in the sequence. The sequence removes pseudo-multi path, determines the number and position of true multi path and conforms signal noise ratio by utilizing the identified numbers and location of multi path, and then chooses the largest one as the main path and determines the location of precise synchronization position. In no less than the precision of the existing synchronous method, the method of the invention improves operation speed; the invention has the advantages of small time synchronization error and less operation. In addition, the method need not have two-step of rough and precise synchronization, which can directly get time synchronous error. The invention is very suitable for real-time processing.

Description

technical field [0001] The present invention relates to multiple input multiple output (MIMO, Multiple Input Multiple Output) and orthogonal frequency division multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) technology in wireless communication, especially relates to time synchronization technology in MIMO OFDM system. Background technique [0002] OFDM technology makes full use of the orthogonality between sub-carriers, allows the spectrum of sub-channels to overlap each other, and can make use of spectrum resources to a large extent; converts high-speed data streams through serial-to-parallel conversion, so that the data symbols on each sub-carrier last for a long time Relatively increased, thus effectively reducing the ISI (Intersymbol Interference) caused by the time dispersion of the wireless channel; at the same time, because the bandwidth of each sub-channel is relatively narrow, equalization can be performed on each sub-carrier separately, thus reducin...

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Problems solved by technology

[0005] However, while the combination of MIMO and OFDM has the above advantages, it does not eliminate their own shortcomings: OFDM has very high requirements for time and frequency synchronization, otherwise it will easily lead to intersymbol interference (ISI) and intercarrier interference (ICI)

The synchronization symbol of this method contains multiple identical partial subsets, and the accurate synchronization information of symbols can be obtained by using the correlation method, but the correlation peak of this method is relatively wide during symbol synchronization, and it is difficult to judge the best symbol synchronization moment , while the synchronization overhead needs to perform multiple FFT operations, the system resource consumption is too large

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