Method of orthogonal frequency division multiplexing (OFDM) frame timing synchronization based on Institute of Electrical and Electronic Engineers (IEEE) 802.11a

Abstract

The invention provides a method of orthogonal frequency division multiplexing (OFDM) frame timing synchronization based on Institute of Electrical and Electronic Engineers (IEEE) 802.11a, belonging to a wireless digital communication technology. The method comprises the following steps: receiving data signals by a receiver, and realizing crude frame timing synchronization by using an delay and correlation algorithm so as to obtain thick frame timing synchronization signals; processing the data signals by a thick frequency offset module and a thin frame timing module in sequence, and realizingthin frame timing synchronization by a cross-correlation algorithm so as to obtain thin frame timing synchronization signals; generating valid data beginning signals payload and data arriving counting signals count by combination control of control signals; controlling removing-cyclic prefixes by the valid data beginning signals payload to carry out fast Fourier transform (FFT) algorithm and channel estimation on the data, and controlling the calculation of carrier frequency offsets by the data arriving counting signals count; and controlling removing-cyclic prefixes (cp) by the valid data beginning signals to carry out the FFT algorithm and the channel estimation on the data. The method is used to reduce the complexity, improve the accuracy, and solve the problem of dispersing and revolving data constellation diagrams.

Description

technical field [0001] The invention relates to an OFDM frame timing synchronization method based on IEEE802.11a, belonging to the technical field of wireless digital communication. Background technique [0002] OFDM (Orthogonal Frequency Division Multiplexing) is Orthogonal Frequency Division Multiplexing technology, which is a kind of MCM (Multi-Carrier Modulation) multi-carrier modulation. The frequency selective fading of the channel is overcome by reducing and eliminating the influence of intersymbol interference. And since the bandwidth of each sub-channel is only a small part of the original channel bandwidth, channel equalization becomes relatively easy. Since the frequency spectrums of the subcarriers overlap with each other, higher frequency spectrum efficiency can be obtained. The OFDM system also has obvious deficiencies, that is, it is very sensitive to phase noise and carrier frequency offset. The entire OFDM system has extremely strict requirements on the or...

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Problems solved by technology

The OFDM system also has obvious deficiencies, that is, it is very sensitive to phase noise and carrier frequency offset. The entire OFDM system has extremely strict requirements on the orthogonality between subcarriers. Any small carrier frequency offset will destroy the relationship between subcarriers. Orthogonality, causing ICI (Inter-Channel Interference), similarly, phase noise will also cause the rotation and diffusion of symbol constellation points, thus forming ICI

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