Frequency synchronizing method and frequency synchronizing apparatus
OwnerKoji Matsuyama, Makoto Yoshida +1inventors
InventorsKoji Matsuyama, Makoto Yoshida, Tetsuya Yano
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Abstract
A frequency synchronizing apparatus synchronizes the oscillation frequency of a receiving device to the oscillation frequency of a transmitting device. The frequency synchronizing apparatus receives, from the transmitting device, frames in which symbols having identical time profiles have been embedded, calculates a correlation value between the identical time profile portions in neighboring frames of a receive signal, obtains the phase of the correlation value (a complex number) as a frequency deviation between the transmitting device and the receiving device, and controls oscillation frequency based upon the phase.
Claims20
A frequency synchronizing method in an OFDM wireless system for synchronizing oscillation frequency of a receiving device to oscillation frequency of a transmitting device, comprising steps of:
- receiving, from the transmitting device, frames in which symbols having identical time profiles have been embedded;
- calculating a correlation value between the identical time profile portions in neighboring frames of a receive signal;
- obtaining the phase of said correlation value as a frequency deviation between the transmitting device and the receiving device;
- and
- controlling oscillation frequency based upon said phase.
A frequency synchronizing method in an OFDM wireless system for synchronizing oscillation frequency of a receiving device to oscillation frequency of a transmitting device, comprising steps of:
- receiving, from the transmitting device, frames in which n-number of first to nth symbols having prescribed time profiles have been embedded;
- calculating and summing correlation values of n sets of corresponding time profile portions in neighboring frames of a receive signal;
- obtaining the phase of said sum value as a frequency deviation between the transmitting device and the receiving device;
- and
- controlling oscillation frequency based upon said phase.
A frequency synchronizing method in an OFDM wireless system for synchronizing oscillation frequency of a receiving device to oscillation frequency of a transmitting device, comprising steps of:
- receiving, from the transmitting device, frames having a plurality of symbols in which a guard interval has been inserted and in which symbols having identical time profiles have been embedded;
- calculating a correlation value (a first correlation value) between a time profile in a guard interval and a time profile of a symbol portion that has been copied to a guard interval, obtaining the phase of said first correlation value as a frequency deviation between the transmitting device and the receiving device, and controlling oscillation frequency based upon said phase;
- and
- when a predetermined condition holds, calculating a correlation value (a second correlation value) between identical time profile portions in mutually adjacent frames of a receiving signal, obtaining the phase of said second correlation value as a frequency deviation between the transmitting device and the receiving device, and controlling oscillation frequency based upon said phase.
A frequency synchronizing method in an OFDM wireless system for synchronizing oscillation frequency of a receiving device to oscillation frequency of a transmitting device, comprising steps of:
- receiving, from the transmitting device, frames having a plurality of symbols in which a guard interval has been inserted and in which n-number of first to nth symbols having prescribed time profiles have been embedded;
- calculating a correlation value (a first correlation value) between a time profile in a guard interval and a time profile of a symbol portion that has been copied to a guard interval, obtaining the phase of said first correlation value as a frequency deviation between the transmitting device and the receiving device, and controlling oscillation frequency based upon said phase;
- and
- when a predetermined condition holds, calculating and summing correlation values of n sets of corresponding time profile portions of two neighboring frames of a receive signal, obtaining the phase of said sum value as a frequency deviation between the transmitting device and the receiving device, and controlling oscillation frequency based upon said phase.
A frequency synchronizing apparatus for synchronizing oscillation frequency of an OFDM receiving device to oscillation frequency of an OFDM transmitting device, comprising:
- a receiving unit for receiving frames in which symbols having identical time profiles have been embedded;
- a correlation arithmetic unit for calculating a correlation value between the identical time profile portions in neighboring frames of a receive signal;
- a phase detector for obtaining the phase of said correlation value as a frequency deviation between the transmitting device and the receiving device;
- and
- an oscillation frequency controller for controlling oscillation frequency based upon said phase.
A frequency synchronizing apparatus for synchronizing oscillation frequency of an OFDM receiving device to oscillation frequency of an OFDM transmitting device, comprising:
- a receiving unit for receiving frames in which n-number of first to nth symbols having prescribed time profiles have been embedded;
- a correlation arithmetic unit for calculating and summing correlation values of n sets of corresponding time profile portions in neighboring frames of a receive signal;
- a phase detector for obtaining the phase of said sum value as a frequency deviation between the transmitting device and the receiving device;
- and
- an oscillation frequency controller for controlling oscillation frequency based upon said phase.
A frequency synchronizing apparatus for synchronizing oscillation frequency of an OFDM receiving device to oscillation frequency of an OFDM transmitting device, comprising:
- a receiving unit for receiving frames having a plurality of symbols in which a guard interval has been inserted and in which symbols having identical time profiles have been embedded;
- first frequency control means for calculating a correlation value (a first correlation value) between a time profile in a guard interval and a time profile of a symbol portion that has been copied to a guard interval, obtaining the phase of said first correlation value as a frequency deviation between the transmitting device and the receiving device, and controlling oscillation frequency based upon said phase;
- second frequency control means for calculating a correlation value (a second correlation value) between identical time profile portions in mutually adjacent frames of a receiving signal, obtaining the phase of said second correlation value as a frequency deviation between the transmitting device and the receiving device, and controlling oscillation frequency based upon said phase;
- and
- control changeover means for changing over frequency control to the second frequency control means when said phase has fallen below a set value by control performed by the first frequency control means or when a set period of time has elapsed since start of control by the first frequency control means.
A frequency synchronizing apparatus for synchronizing oscillation frequency of an OFDM receiving device to oscillation frequency of an OFDM transmitting device, comprising:
- a receiving unit for receiving frames having a plurality of symbols in which a guard interval has been inserted and in which n-number of first to nth symbols having prescribed time profiles have been embedded;
- first frequency control means for calculating a correlation value (a first correlation value) between a time profile in a guard interval and a time profile of a symbol portion that has been copied to a guard interval, obtaining the phase of said first correlation value as a frequency deviation between the transmitting device and the receiving device, and controlling oscillation frequency based upon said phase;
- second frequency control means for calculating and summing correlation values of n sets of corresponding time profile portions of two neighboring frames of a receive signal, obtaining the phase of said sum value as a frequency deviation between the transmitting device and the receiving device and controlling oscillation frequency based upon said phase;
- and
- control changeover means for changing over frequency control to the second frequency control means when said phase has fallen below a set value by control performed by the first frequency control means or when a set period of time has elapsed since start of control by the first frequency control means.
Dependencies are inferred from the claim text.