Eureka AIR delivers breakthrough ideas for toughest innovation challenges, trusted by R&D personnel around the world.

OFDM (orthogonal frequency division multiplexing) self-adaptive synchronization method under multipath channel

An adaptive and channel technology, applied in the multi-frequency code system and other directions, can solve the problem of high complexity, achieve stable performance and reasonable step size selection.

Inactive Publication Date: 2011-04-27
XIDIAN UNIV
View PDF0 Cites 2 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although its performance is good, the complexity is much higher than the maximum likelihood method

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 more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • OFDM (orthogonal frequency division multiplexing) self-adaptive synchronization method under multipath channel
  • OFDM (orthogonal frequency division multiplexing) self-adaptive synchronization method under multipath channel
  • OFDM (orthogonal frequency division multiplexing) self-adaptive synchronization method under multipath channel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0024] Below in conjunction with accompanying drawing, the implementation of the present invention is described in detail:

[0025] refer to figure 1 , the specific implementation steps of the present invention include as follows:

[0026] Step 1: For the first OFDM symbol received, use the maximum likelihood method to select the initial point of synchronization parameter estimation, that is, the reference point of the first iteration, and initialize the access probability vector, the number of moving points and the step size factor.

[0027] (1a) [0, N+N cp The value of θ in the range of -1] is substituted into the following traditional cost function G(θ), and the sample number θ corresponding to the maximum value of the absolute value of the cost function is selected as the initial point of iteration,

[0028] G ( θ ) = Σ i = 0 ...

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

No PUM Login to View More

Abstract

The invention discloses an OFDM (orthogonal frequency division multiplexing) self-adaptive synchronization method under a multipath channel, which is mainly used for solving the problems of slow tracking and unstable convergence of the traditional self-adaptive method, as well as inaccurate convergence under the multipath channel. The specific steps are as follows: 1) selecting an iteration initial point and carrying out parameter initialization; 2) calculating a cost function of a current point and an adjacent point, and moving towards the direction of the biggest cost function value; 3) judging whether the moving direction is the same with that at the last time or not, and updating the number of moving points; 4) judging whether the peak value of an access probability vector is higher than a threshold value or not, if so, updating the access probability vector and a step factor, otherwise, updating the access probability vector and the step factor; 5) estimating time delay and frequency offset according to the access probability vector; and 6) getting the next OFDM symbol and stating a new round of iteration. The method has the advantages of fast tracking speed, high convergence stability and accurate estimation result, and can be used for fast synchronous parameter estimation under the multipath channel.

Description

technical field [0001] The invention belongs to the field of wireless communication, in particular to a fast and accurate synchronization method in an OFDM system, which is used to solve the problem of slow tracking, unstable convergence and poor performance in multi-path channels in traditional adaptive synchronization methods question. Background technique [0002] OFDM has been used more and more widely by virtue of its own advantages, and will become the mainstream technology in the third generation of mobile communication 3G. But at the same time, its sensitivity to synchronization error cannot be ignored. The synchronization error of time and frequency will destroy the orthogonality between sub-carriers, thereby introducing inter-carrier interference and inter-symbol interference, which greatly reduces system performance. [0003] The sensitivity of OFDM to synchronization errors has led many literatures to focus on the research of synchronization algorithms. Among th...

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
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26
Inventor 李明陈健何书朋阔永红
Owner XIDIAN UNIV
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com