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 OFDM signal identification difficulties, unsuitable multi-path Rayleigh fading channels, etc., and achieve high identification probability and multiple offsets Effects of Rayleigh fading and Doppler shift, low complexity
Inactive Publication Date: 2010-04-21
XIDIAN UNIV
View PDF2 Cites 0 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
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
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0034] Principle of the present invention and technical scheme are described in further detail below:
[0035] refer to figure 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 , adding the signals of each path to get the signal After the signal is superimposed with additive Gaussian white noise ω(t), the final received signal is r(t)=y(t)+ω(t).
[0036] figure 1 , the Rayleigh fading factor h of the l-th path l (t) satisfy independent and identical distribution, h l (t) can be expressed as its magnitude a l (t) obey Rayleigh distribution, phase Obey the uniform distribution of [0~2π]; the mean value of additive Gaussian noise ω(t) is O, and the variance is σ ω ; signal, Rayleigh fading and Gaussian noise are independent of e...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
Login to View More 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 counteractthe 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 ofeigenvalue; 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 inventionp ossesses 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...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26H04B1/707
Inventor 赵林靖刘妍李建东李雯雯
Owner XIDIAN UNIV