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A method for signal processing and a signal processor in an OFDM system

A technology for digital signal and signal reception, applied in the fields of mobile devices, communication systems, and signal processors, it can solve problems such as impossible reliable detection

Inactive Publication Date: 2007-05-09
KONINKLIJKE PHILIPS ELECTRONICS NV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This intercarrier interference increases with vehicle speed and makes reliable detection impossible without measures above a critical speed

Method used

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  • A method for signal processing and a signal processor in an OFDM system
  • A method for signal processing and a signal processor in an OFDM system
  • A method for signal processing and a signal processor in an OFDM system

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Embodiment Construction

[0027] Figure 1 is a graph showing the variation of the subcarrier channel transfer function H(f) perceived by the receiver as a function of frequency and time in a mobile environment. Variations in H(f) in an OFDM symbol lead to inter-carrier interference ICI appearing between the OFDM subcarriers, which is the so-called Doppler broadening of the received signal.

[0028] Figure 2 shows the desired variation of this signal over frequency, represented by the upper solid line 1. The sum of this ICI and noise is represented by a dashed line 2 . The difference between the curves is the signal-to-interference-noise ratio, SINR. However, ICI increases with vehicle speed, which makes reliable detection impossible without measures above critical speeds.

[0029] According to the present invention, it is observed that for all reasonable vehicle speeds and subcarrier frequencies, the channel transfer function H varies almost linearly as a function of time for the duration of one OFDM...

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PUM

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Abstract

A method of signal processing for a receiver for OFDM encoded digital signals, for counteracting inter-carrier interference (ICI) caused by Doppler broadening. The OFDM encoded digital signals are transmitted as sub-carriers in several channels, which form OFDM blocks. The method comprises estimation of a channel transfer function (H1) by a channel estimation scheme in each sub-carrier and estimation of data (a1) by a data estimation scheme from said channel transfer function (H1) and a received signal (y0). Then, a derivative (Hj') of said channel transfer function in each sub-carrier is estimated by a temporal filtering; and the inter-carrier interference (ICI) is removed from said received signal by using the estimated data (a1) and the estimated derivative (Hj' ) of the channel transfer function in order to obtain a cleaned received signal (y1).

Description

technical field [0001] The invention relates to a signal processing method of a receiver for encoding digital signals in a wireless communication system, and a corresponding signal processor. [0002] The invention also relates to a receiver for receiving the OFDM coded signal, and a mobile device comprising such a receiver. The invention also relates to a communication system comprising a mobile device. The method can be used to mitigate inter-carrier interference (ICI) eg caused by Doppler broadening eg in the terrestrial video broadcasting system DVB-T using OFDM technology. [0003] A mobile device may be, for example, a portable television, a mobile phone, a personal digital assistant (PDA) or a mobile computer such as a laptop or any combination thereof. Background technique [0004] In wireless systems for transmitting digital information, such as transmitting voice or video signals, Orthogonal Frequency Division Multiplexing (OFDM) technology is widely used. OFDM ...

Claims

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Application Information

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IPC IPC(8): H04L25/03H04L27/26H04L25/02
CPCH04L2025/03522H04L25/0234H04L2025/03414H04L27/2647H04L2025/03605
Inventor C·P·M·J·巴根S·A·胡森M·L·A·斯塔森H·Y·曾
Owner KONINKLIJKE PHILIPS ELECTRONICS NV
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