US 7,627,047 B2 · Orthogonal frequency division multiplexing (OFDM) receiver

Abstract

An OFDM receiver apparatus mounted on a movable object for receiving an OFDM signal, includes a plurality of directional antennas which receive an OFDM signal, an estimator to estimate a center frequency of a spectrum of a Doppler component from one of the received signals or a multiplexed signal obtained by multiplexing the received signals, a shift quantity calculator to calculate a shift quantity from the estimated center frequency of the estimator and directivity information representing directivity directions of the directional antennas, a plurality of frequency shifters to subject the received signals to frequency shift according to the shift quantity to compensate for Doppler shift, a combining unit to diversity-combine frequency shifted signals of the frequency shifters, and a demodulator/decoder to demodulate and decode combining diversity signals of the combining unit.

Claims19

Dependent claims

An OFDM receiver apparatus mounted on a movable object for receiving an orthogonal frequency division multiplex (OFDM) signal, the OFDM receiver apparatus comprising:

a plurality of directional antennas which receive an OFDM signal and output received signals, respectively;
a moving velocity detector to detect a moving velocity of the movable object;
a calculator to calculate a maximum Doppler center frequency from the moving velocity;
an estimator to estimate a center frequency of a spectrum of a Doppler component in a frequency band not more than the maximum Doppler frequency from one of the received signals or a multiplexed signal obtained by multiplexing the received signals;
a shift quantity calculator to calculate at least one shift quantity from the estimated center frequency of the estimator and directivity information representing directivity directions of the directional antennas;
a plurality of frequency shifters to subject the received signals to frequency shift according to the shift quantity to compensate for Doppler shift;
a combining unit configured to diversity-combine frequency shifted signals of the frequency shifters;
and
a demodulator/decoder to demodulate and decode combining diversity signals of the combining unit.

6 more elements

A method of receiving an orthogonal frequency division multiplex (OFDM) signal with an OFDM receiver apparatus mounted on a movable object, the method comprising:

receiving an OFDM signal with a plurality of directional antennas to obtain a plurality of received signals;
detecting a moving velocity of the movable object;
calculating a maximum Doppler center frequency from the moving velocity;
estimating a center frequency of a spectrum of a Doppler component in a frequency band not more than the maximum Doppler frequency from one of the received signals or a multiplexed signal obtained by multiplexing the received signals;
calculating at least one shift quantity from the estimated center frequency and directivity information representing directivity directions of the directional antennas;
frequency-shifting the received signals according to the shift quantity to compensate for Doppler shift;
diversity-combining frequency shifted signals obtained by the frequency-shifting;
and
demodulating and decoding combining diversity signals obtained by the diversity-combining.

6 more elements

Dependencies are inferred from the claim text.

Orthogonal frequency division multiplexing (OFDM) receiver

Life of this patent

Orthogonal frequency division multiplexing (OFDM) receiver

Life of this patent

Abstract

Claims19