MIMO-OFDM channel estimator designed based on quadratic curve fitting method

Abstract

The invention discloses an MIMO-OFDM channel estimator designed based on a quadratic curve fitting method. The channel estimator comprises a transmitting end and a receiving end, and is characterized in that the transmitting end comprises multiple groups of pilot frequencies which are distributed in OFDM symbols in equal distance; zero pilot frequencies and non-zero pilot frequencies in each group of pilot frequencies are mixed at a subcarrier to be alternatively inserted, and the zero pilot frequencies serve as protection intervals; the receiving end is used for receiving a signal transmitted by the transmitting end and calculating the estimated value and filter coefficient at the zero pilot frequencies by virtue of FFT transform; and the estimated value and filter coefficient at the zero pilot frequencies are respectively calculated by virtue of the quadratic curve fitting method of a six-point smoothing filter. The condition that the channel estimation is damaged by an improper averaging method is avoided. According to the STBC technology, LS operation of a multidimensional matrix is transformed into a one-dimensional matrix operation, the complexity is reduced, the estimation accuracy of a traditional channel estimation method is improved based on the optimization thought of the system, and the signal-to-noise ratio application range is widened.

Description

technical field [0001] The present invention relates to the technical field of communication, and more specifically relates to a MIMO-OFDM channel estimator designed based on a quadratic curve fitting method. Background technique [0002] The development and application of Wireless Local Area Network (WLAN) technology has profoundly changed the way people communicate and work, bringing unprecedented convenience to people. In addition, various smart terminals (such as Smart Phone, iPad, IPTV, etc. ) and the introduction and implementation of the concept of "Smart Home", people have higher and higher requirements for the convenience brought by WLAN and the efficiency of signal transmission. Under high-speed transmission, the Orthogonal Frequency Division Multiplexing (OFDM) signal is transmitted in the channel. Due to the influence of frequency selective fading, Doppler frequency shift and carrier frequency offset, its phase will shift and its amplitude will attenuate. In ord...

AI Technical Summary

Problems solved by technology

In previous studies, the MIMO wireless transmission channel has a large coherence time, especially when the subcarrier DC corresponds to X0 = 0, the channel estimation algorithm cannot find the corresponding channel gain at DC

At the same time, under the 802.11n protocol, the receiver extracts two long training sequence symbols from the long training sequence (LTF) for channel estimation. The time-varying characteristics of the channel caused by relative motion cause inter-carrier interference in the OFDM system, which seriously affects communication quality

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