Time domain windowing and inter-carrier interference cancellation

A technology of time and sub-carrier, applied in the direction of modulated carrier system, multi-frequency code system, digital transmission system, etc., can solve complex problems

Inactive Publication Date: 2008-06-18
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The scheme is complex because many subcarriers form ICI, especially when the signal-to-noise ratio is critical, as it is used in high data rate systems with advanced modulations such as 64QAM

Method used

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  • Time domain windowing and inter-carrier interference cancellation
  • Time domain windowing and inter-carrier interference cancellation
  • Time domain windowing and inter-carrier interference cancellation

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Embodiment Construction

[0066] The various features of the present invention will now be described with reference to the drawings, in which like parts are identified by the same reference numerals.

[0067] Various aspects of the invention are now described in more detail in connection with a number of exemplary embodiments. To facilitate understanding of the invention, aspects of the invention are described in terms of sequences of actions to be performed by elements of a computer system or other hardware capable of executing program instructions. It will be appreciated that in each of the embodiments, the various actions may be performed by dedicated circuitry (such as discrete logic gates interconnected to perform specific functions), by program instructions executed by one or more processors, or by a combination of both . Furthermore, the present invention is also contemplated to be entirely in any form, such as solid-state memory, magnetic disk, optical disk, or carrier wave (e.g., radio freque...

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Abstract

Inter-carrier interference (ICI) in a kth sub-carrier of an orthogonal frequency division multiplexing (OFDM) signal received at time t is reduced, wherein the received OFDM signal comprises a plurality of sub-carriers. This is achieved by generating a self-interference term, ICIk−L,k−L, for a signal received on sub-carrier k−L, wherein L ∈ [ . . . , −3,−2,−1,1,2,3, . . . ], and wherein the self-interference term is an estimate of the data received at time t on the sub-carrier k−L, weighted by a rate of change of the channel through which sub-carrier k−L passes at time t. An ICI cancellation coefficient, GL is obtained, and an estimated ICI term is generated by adjusting the self-interference term, ICIk−L,k−L, by an amount based on the ICI cancellation coefficient, GL. The estimated ICI term is then subtracted from a term representing a signal received on the kth sub-carrier at time t.

Description

technical field [0001] The present invention relates to digital communications employing Orthogonal Frequency Division Multiplexing (OFDM), and more particularly to the cancellation of intercarrier interference between OFDM subcarriers. Background technique [0002] In an OFDM system, a signal consists of multiple subcarriers independently modulated with respective data. Modulation can be according to a variety of well-known techniques, such as quadrature amplitude modulation (QAM) or n-phase shift keying (n-PSK). The baseband signal in the OFDM system is the sum of these modulated subcarriers. The baseband signal is used to modulate the main radio frequency (RF) signal. An important aspect of demodulating such a signal (and thus recovering the underlying baseband signal) involves processing it through a Fast Fourier Transform (FFT). One advantage of communicating by OFDM is that it allows communicating over highly time-dispersive channels (ie due to multipath propagation...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26
CPCH04L25/03821H04L25/03006H04L27/2607H04L27/2647H04L25/0216H04L27/26H04B15/00
Inventor L·威廉森M·福尔克纳
Owner TELEFON AB LM ERICSSON (PUBL)
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