Adaptive modulation-demodulation method base on fractional order Fourier transform

A fractional Fourier, adaptive modulation technique for error prevention/detection through diversity reception, multi-frequency code systems, etc.

Inactive Publication Date: 2010-09-08
BEIJING INSTITUTE OF TECHNOLOGYGY
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Currently, there are several different types of fast algorithms f

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  • Adaptive modulation-demodulation method base on fractional order Fourier transform
  • Adaptive modulation-demodulation method base on fractional order Fourier transform
  • Adaptive modulation-demodulation method base on fractional order Fourier transform

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[0121] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0122] The principle block diagram of adaptive modulation of MIMO-OFDM system based on fractional Fourier transform is as follows: figure 2 As shown, it is a MIMO-OFDM adaptive modulation system based on fractional Fourier transform designed and implemented according to the technical solution of the present invention. The transmitting end of the system includes an optimal order selection module, an adaptive bit and a codec design module , a source module, a serial-to-parallel conversion module, a digital modulation module, a precoding module, and an OFDM modulation module of fractional Fourier transform. The receiving end includes a channel estimation module, an OFDM demodulation module of fractional Fourier transform, a decoding module, a Fourier domain equalization module, a digital demodulation module, and a parallel-to-serial conversion module.

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Abstract

The invention provides an adaptive modulation-demodulation method base on fractional order Fourier transform, aiming at reducing influence caused by feedback time delay specific to an MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) adaptive modulation system which has feedback time delay, and enabling the system to have better performance in a fast time-varying channel. The method has the technical scheme that inverse discrete fractional order Fourier transform is used to replace inverse discrete Fourier transform for carrying out subcarrier modulation at a transmitting terminal, discrete fractional order Fourier transform is used to replace discrete Fourier transform for carrying out subcarrier demodulation at a receiving terminal, the optimal fractional order Fourier transform order selection is carried out by channel estimation information fed back to the transmitting terminal by the receiving terminal, the deviation between the current channel state information and the feedback channel state information is reduced and the performance of the system having time delay is enhanced.

Description

field of invention [0001] The invention relates to an adaptive modulation and demodulation technology in a MIMO-OFDM system, and belongs to the field of multi-carrier digital communication. Background technique [0002] Multiple Input Multiple Output - Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a new high-speed data transmission technology. The MIMO technology can significantly increase the channel capacity of the wireless communication system and enhance the reliability of data transmission by using multiple transmitting antennas and receiving antennas. OFDM technology can convert frequency-selective fading channels into a group of orthogonal flat fading channels, so OFDM technology can be applied in MIMO systems to overcome the influence of multipath fading. MIMO-OFDM technology is considered by the industry to be the main physical layer technology of the fourth generation mobile communication system in the future. [0003] In a wireless communication syst...

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Application Information

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IPC IPC(8): H04L27/26H04L1/06
Inventor 陶然杨倩倪佳
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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