Ofdm receiving method and apparatus
AssigneeFujitsu Limited
InventorsMakoto Yoshida, Yoshinori Tanaka
Life of this patent
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Abstract
In order to improve upon a degradation in performances due to inter-carrier interference without loss of transmission efficiency, antennas provided on a mobile body are made directional antennas. An antenna selection unit selects a directional antenna in such a manner that Doppler shift that is caused by movement of the mobile body will keep a constant sign that is positive or negative, a fading-variation calculation unit calculates the average value of fading variation on each path of a multipath environment, and a fading-variation compensation unit compensates the multipath fading variation based upon the average value.
Claims7
1-25. (canceled)
An OFDM receiving method of a mobile body for receiving a signal multiplexed according to Orthogonal Frequency Division Multiplexing (OFDM) and applying FFT processing to the received signal to demodulate transmit data, comprising the steps of:
- receiving an OFDM signal with a directional antenna on the mobile body, the directional antenna having directivity in a direction of moving or in a direction opposite the direction of moving;
- calculating, prior to FFT processing, an average value of fading-variation in a multipath environment using the received signal;
- and
- compensating the fading-variation based upon the average value, wherein correlation between the received signal and a received signal one OFDM symbol time earlier is calculated and the average value of fading-variation in the multipath environment is calculated based upon a correlation vector obtained.
An OFDM receiving method for receiving a signal multiplexed according to Orthogonal Frequency Division Multiplexing (OFDM) and applying FFT processing to the received signal to demodulate transmit data, comprising the steps of:
- providing a mobile body with a plurality of directional antennas having directivities that differ from one another and include a directivity in a direction of moving or in a direction opposite the direction of moving;
- selecting a directional antenna in such a manner that Doppler shift that is caused by movement of the mobile body will keep a constant sign that is positive or negative;
- calculating, prior to FFT processing, an average value of fading-variation in a multipath environment using a received signal from the antenna that has been selected;
- and
- compensating the fading-variation based upon the average value, wherein correlation between the received signal and a received signal one OFDM symbol time earlier is calculated and the average value of fading-variation in the multipath environment is calculated based upon a correlation vector obtained.
An OFDM receiving method for receiving a signal multiplexed according to Orthogonal Frequency Division Multiplexing (OFDM) and applying FFT processing to the received signal to demodulate transmit data, comprising the steps of:
- providing a mobile body with a plurality of directional antennas having directivities that differ from one another and include directivity in a direction of moving or in a direction opposite the direction of moving and adopting these directional antennas as antennas of independent branches;
- calculating, prior to FFT processing, an average value of fading-variation in a multipath environment using an antenna received signal branch by branch;
- compensating the fading-variation based upon the average value branch by branch;
- and
- diversity-combining results of FFT processing from respective ones of the branches, wherein correlation between the received signal and a received signal one OFDM symbol time earlier is calculated and the average value of fading-variation in the multipath environment is calculated based upon a correlation vector obtained.
An OFDM receiving apparatus in a mobile body for receiving a signal multiplexed according to Orthogonal Frequency Division Multiplexing (OFDM) and applying FFT processing to the received signal to demodulate transmit data, comprising:
- a directional antenna on the mobile body, having directivity in a direction of moving or in a direction opposite the direction of moving;
- an OFDM signal receiver for receiving an OFDM signal with the directional antenna;
- a fading-variation calculation unit for calculating, prior to FFT processing, an average value of fading-variation in a multipath environment using the received signal by the directional antenna;
- a fading-variation compensation unit for compensating the fading-variation based upon the average value;
- and
- an FFT unit for applying FFT processing to a signal obtained by the fading compensation, wherein said fading-variation calculation unit calculates correlation between the received signal and a received signal one OFDM symbol time earlier and calculates the average value of fading-variation in the multipath environment based upon a correlation vector obtained.
An OFDM receiving apparatus for receiving a signal multiplexed according to Orthogonal Frequency Division Multiplexing (OFDM) and applying FFT processing to the received signal to demodulate transmit data, comprising:
- a plurality of directional antennas having directivities that differ from one another and include a directivity in a direction of moving or in a direction opposite the direction of moving, provided on a mobile body;
- a directional antenna selecting unit for selecting a directional antenna in such a manner that Doppler shift that is caused by movement of the mobile body will keep a constant sign that is positive or negative;
- a fading-variation calculation unit for calculating, prior to FFT processing, an average value of fading-variation in a multipath environment using a received signal from the antenna that has been selected;
- a fading-variation compensation unit for compensating the fading-variation based upon the average value;
- and
- an FFT unit for applying FFT processing to a signal obtained by the fading compensation, wherein said fading-variation calculation unit calculates correlation between the received signal and a received signal one OFDM symbol time earlier and calculates the average value of fading-variation in the multipath environment based upon a correlation vector obtained.
An OFDM receiving apparatus for receiving a signal multiplexed according to Orthogonal Frequency Division Multiplexing (OFDM) and applying FFT processing to the received signal to demodulate transmit data, comprising:
- a plurality of directional antennas having directivities that differ from one another and include directivity in a direction of moving or in a direction opposite the direction of moving, provided on a mobile body and constructing respective ones of separate branches;
- a fading-variation calculation unit for calculating, prior to FFT processing, an average value of fading-variation in a multipath environment using an antenna received signal branch by branch;
- a fading-variation compensation unit for compensating the fading-variation based upon the average value branch by branch;
- an FFT unit for applying FFT processing to a signal obtained by the fading compensation;
- and
- a diversity combiner for diversity-combining results of FFT processing from respective ones of the branches, wherein said fading-variation calculation unit calculates correlation between the received signal and a received signal one OFDM symbol time earlier and calculates the average value of fading-variation in the multipath environment based upon a correlation vector obtained.
Dependencies are inferred from the claim text.