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Method for identifying OFDM modulation system of multi-path Rayleigh fast fading channel

A fading channel and identification method technology, applied in multi-frequency code systems, transmission systems, electrical components, etc., can solve the problems of difficulty in OFDM signal identification and inapplicability to multipath Rayleigh fading channels, etc.

Inactive Publication Date: 2007-12-05
XIDIAN UNIV
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Problems solved by technology

But this algorithm only considers single-path Rayleigh fading, not suitable for multi-path Rayleigh fading channels
[0007] It can be seen that there is no research on the identification of OFDM signals and single-carrier signals under the actual multipath Rayleigh fast fading channel conditions in the current literature
Moreover, because the higher the order of the quadrature amplitude modulation QAM signal, the more difficult it is to distinguish it from the OFDM signal. The highest order of the single carrier signal selected in the current literature can only reach 128QAM

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  • Method for identifying OFDM modulation system of multi-path Rayleigh fast fading channel
  • Method for identifying OFDM modulation system of multi-path Rayleigh fast fading channel

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Embodiment Construction

[0035] Principle of the present invention and technical scheme are described in further detail below:

[0036] Referring to Fig. 1, the present invention is an OFDM identification researched under an L-path frequency selective mobile channel. The propagation delay τ of the transmitted signal s(t) through the lth path l and Rayleigh fading h l (t) and the Doppler shift f dl After that, the signal of the lth path is s(t-τ l )e j2πfdlt , adding the signals of each path to get the signal y ( t ) = Σ l = 1 L h l ( t ) s ( t - τ l ) e j 2 π ...

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Abstract

Using expressions of cumulant in second, fourth, and sixth orders of signal of passing through multipath Rayleigh fast fading channel (MRFFC), the method carries out combination in order to counteract the influence of multipath Rayleigh fading and Doppler shift. Concrete process includes steps: after mixing, oversampling, and orthogonal interpolating signals received, receiver obtains orthogonal plural sequence in mid frequency; calculating cumulant in second, fourth, and sixth orders; combining cumulant in fourth and second orders as well as sixth and second orders so as to obtain two types of eigenvalue; setting up threshold of the eigenvalue, comparing the two types of eigenvalue to the threshold so as to identify OFDM signal and single carrier signal. Comparing prior art, the invention possesses advantages of high probability of identification, low complexity, suitable to processing in real time. The invention is applicable to identifying OFDM modulation format in mid frequency.

Description

technical field [0001] The invention belongs to the field of communication signal processing, and relates to a modulation system identification method for OFDM signals and single-carrier signals, which can be used under multipath Rayleigh fast-fading channel conditions. Background technique [0002] The purpose of communication is to transmit information quickly, efficiently, safely and accurately through channels. In order to meet different needs of users and make full use of channel capacity, communication signals adopt different modulation methods. With the rapid development of electronic technology and the continuous improvement of users' requirements for information transmission, the communication signal modulation method has experienced a development process from analog to digital, from simple to complex. [0003] Different modulation methods are used for space-propagated communication signals. In many applications, it is necessary to monitor the activity of communic...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04B1/707
Inventor 赵林靖刘妍李建东李雯雯
Owner XIDIAN UNIV
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