Apparatus and method for estimating frequency offset
AssigneesSamsung Electronics Co., Ltd., Electronics and Telecommunications Research Institute, Hanaro Telecom, Inc., SK Telecom Co., Ltd., Kt Corporation
InventorsChang-Wahn Yu, Youn-Ok Park
Life of this patent
Estimating the term…
Abstract
In a frequency offset estimating device of a subscriber station of a communication system in which a plurality of sectors are allocated to a cell, the frequency offset estimating device extracts a preamble sequence from a downlink frame signal. The frequency offset estimating device estimates a phase offset of a sector to which the subscriber station belongs among the sectors by using the preamble sequence, and calculates the autocorrelation value for the respective signals of the preamble sequence. The frequency offset estimating device compensates the autocorrelation value by using the phase offset, and estimates a frequency offset from the sum of the phase offset compensated autocorrelation values.
Claims13
A method of estimating a frequency offset by a subscriber station of a communication system in which a plurality of sectors are allocated to a cell, the method comprising:
- extracting a preamble sequence from a downlink frame signal;
- estimating a phase offset of a sector to which the subscriber station belongs from among the sectors by using the preamble sequence;
- calculating autocorrelation values for respective signals of the preamble sequence;
- compensating the autocorrelation values with the phase offset;
- and
- estimating a frequency offset from the sum of phase offset compensated autocorrelation values,
- wherein estimating of the phase offset comprises:
- converting the preamble sequence into a preamble signal in the frequency domain;
- extracting subcarriers of respective sectors from the preamble signal;
- calculating sizes of the subcarriers of the respective sectors;
- calculating received power of the respective sectors from the sizes of the subcarriers of the sectors;
- comparing received power of the respective sectors and detecting a sector to which the subscriber station belongs from among the sectors;
- and
- determining the phase offset of the detected sector, and
- wherein the phase offset is determined by:
- exp
-
- (
- -
- j
-
-
- 2
-
-
- π
-
-
- n
- ×
- s
- N
- )
- ,
- where N indicates a number of preamble sequences, n indicates an index of the preamble sequence in a time domain, and s indicates a number for shifting of the detected sector with respect to the reference sector from among the sectors.
A device for estimating a frequency offset in a subscriber station of a communication system in which a plurality of sectors are allocated to a cell, the device comprising:
- a receiver for receiving a downlink frame signal, and
- a frequency offset estimator for extracting a preamble sequence from the downlink frame signal, estimating a phase offset of a sector to which the subscriber station belongs by using the preamble sequence, and estimating a frequency offset by using the phase offset and the preamble sequence,
- wherein the frequency offset estimator comprises:
- a preamble sequence extractor for extracting the preamble sequence from the downlink frame signal;
- a sector detector for estimating a phase offset of a sector to which the subscriber station belongs by using the preamble sequence;
- an autocorrelation calculator for calculating an autocorrelation value for the signal of the preamble sequence;
- a phase offset compensator for compensating the autocorrelation value by using the phase offset;
- and
- a frequency offset calculator for estimating a frequency offset from the sum of the phase offset compensated autocorrelation values, and
- wherein the phase offset is determined by:
- exp
-
- (
- -
- j2π
-
- n
- ×
- s
- N
- )
- ,
- where N indicates a number of preamble sequences, n indicates an index of the preamble sequence in a time domain, and s indicates a number for shifting of the detected sector with respect to the reference sector from among the sectors.
A recording medium of a communication device for recording a program for realizing a method for estimating a frequency offset in a communication system in which a plurality of sectors are allocated to a cell, the method comprising:
- extracting a preamble sequence from a downlink frame signal;
- estimating a phase offset of the sector to which the subscriber station belongs from among the sectors by using the preamble sequence;
- calculating an autocorrelation value for the respective signals of the preamble sequence;
- compensating the autocorrelation value by using the phase offset, and
- estimating a frequency offset from the phase offset compensated autocorrelation value,
- wherein estimating of the phase offset comprises:
- converting the preamble sequence into a preamble signal in the frequency domain:
- extracting subcarriers of respective sectors from the preamble signal;
- calculating sizes of the subcarriers of the respective sectors;
- calculating received power of the respective sectors from the sizes of the subcarriers of the sectors;
- comparing received power of the respective sectors and detecting a sector to which the subscriber station belongs from among the sectors;
- and
- determining the phase offset of the detected sector, and
- wherein the phase offset is determined by:
- exp
-
- (
- -
- j2π
-
- n
- ×
- s
- N
- )
- ,
- where N indicates a number of preamble sequences, n indicates an index of the preamble sequence in a time domain, and x indicates a number for shifting of the detected sector with respect to the reference sector from among the sectors.
Dependencies are inferred from the claim text.