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Synchronization in OFDM systems

a synchronization and ofdm technology, applied in the field of digital communication, can solve the problems of inability to immediately access information for receivers, inaccurate recovery of ofdm symbols, and loss of data from missychronization, so as to facilitate synchronization, facilitate synchronization, and facilitate synchronization.

Inactive Publication Date: 2005-07-07
JONES VINCENT K IV +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012] By virtue of the present invention, highly effective systems and methods for synchronizing OFDM receiver parameters to an OFDM transmitter are provided. These parameters may include carrier frequency, burst timing, and cyclic prefix length. These systems and methods incorporate special structural features into the OFDM signal to facilitate synchronization. In one embodiment, a supplemental cyclic prefix is added to an OFDM signal to facilitate synchronization. In an alternative embodiment, a synchronization burst with a periodic structure is used to facilitate synchronization. According to the present invention, synchronization may be maintained even if low cost analog oscillator components are used.

Problems solved by technology

Imprecision with respect to the transmission frequency will cause inaccurate recovery of the OFDM symbols.
Again, the consequence of missychronization will be lost data.
This information may not necessarily be immediately available to the receiver in systems where the transmitter is a hub of a point to multipoint system.

Method used

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  • Synchronization in OFDM systems
  • Synchronization in OFDM systems
  • Synchronization in OFDM systems

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Embodiment Construction

OFDM System Overview

[0024]FIG. 1 depicts an OFDM transmitter system 100 according to one embodiment of the present invention. A source 102 originates data symbols to be transmitted in orthogonal frequency domain subchannels. Any channel coding technique or combination of techniques may be applied to the frequency domain data symbols. To assist in estimating characteristics of the channel, training symbols having known values may be interspersed with the data symbols by a training symbol injection system 104. The output of training symbol injection system 104 is a series of N-symbol frequency domain bursts where N is a length of an IFFT procedure applied by an IFFT processing block 106. IFFT processing block 106 generates time domain output bursts from frequency domain input bursts.

[0025] According to the present invention, certain bursts may be special synchronization bursts generated by a synchronization burst generation system 108. As described below, these synchronization bursts...

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Abstract

Highly effective systems and methods for synchronizing OFDM receiver parameters to an OFDM transmitter are provided. These parameters may include carrier frequency, burst timing, and cyclic prefix length. These systems and methods incorporate special structural features into the OFDM signal to facilitate synchronization. In one embodiment, a supplemental cyclic prefix is added to an OFDM signal to facilitate synchronization. In an alternative embodiment, a synchronization burst with a periodic structure is used to facilitate synchronization. According to the present invention, synchronization may be maintained even if low cost analog oscillator components are used.

Description

STATEMENT OF RELATED APPLICATIONS [0001] The present application is a continuation of U.S. patent application Ser. No. 09 / 245,168 titled SYNCHRONIZATION IN OFDM SYSTEMS, filed Feb. 5, 1999. [0002] U.S. patent application Ser. No. 09 / 245,168 and the present invention are related to the subject matter of U.S. application Ser. No. 09 / 244,754 (original Attorney Docket No. CISCP625), entitled ENHANCED SYNCHRONIZATION BURST FOR OFDM SYSTEMS, co-filed and co-assigned with U.S. patent application Ser. No. 09 / 245,168, and now U.S. Pat. No. 6,549,592. [0003] U.S. patent application Ser. No. 09 / 245,168 and the present application are related to and claim the benefit of U.S. Provisional Application No. 60 / 074,331, filed Feb. 6, 1998. [0004] The contents of these three related application are herein incorporated by reference for all purposes.BACKGROUND OF THE INVENTION [0005] The present invention relates to digital communication and more particularly to synchronization of certain parameters bet...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04J3/06H04J11/00H04L27/26
CPCH04L27/2662H04L27/2659H04L27/2678H04L27/2666H04L27/2675H04L27/266
Inventor JONES, VINCENT K. IVPOLLACK, MICHAELRALEIGH, GREGORY G.
Owner JONES VINCENT K IV