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US 8,009,768 B1Granted
Integer frequency offset estimation based on the maximum likelihood principal in OFDM systems
AssigneeMarvell International Ltd.
InventorsJungwon Lee, Dimitrios-Alexandros Toumpakaris, Hui-Ling Lou
Life of this patent
Estimating the term…
Abstract
An apparatus includes an estimator that includes a receiver that receives a plurality of frequency-domain symbols. Each symbol includes at least one of a plurality of pilot samples and a plurality of data samples. The estimator also includes a framer that observes the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols, and a calculator that calculates an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols.
Claims54
An apparatus comprising:
- an estimator including:
- a receiver that receives a plurality of frequency-domain symbols, each symbol including at least one of a plurality of pilot samples and a plurality of data samples;
- a framer that observes the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols, wherein the frequency-domain symbols comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols, the plurality of data samples correspond to a plurality of data subcarriers in the OFDM symbols, and the plurality of pilot samples Correspond to a plurality of pilot subcarriers in the OFDM symbols;
- and
- a calculator that calculates an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols, wherein the integer CFO estimate is
- based on:
- L
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- ,
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159 more elements
An apparatus comprising:
- an estimator including:
- a receiver that receives a plurality of frequency-domain symbols, each symbol including at least one of a plurality of pilot samples and a plurality of data samples;
- a framer that observes the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols, wherein the frequency-domain symbols comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols, the plurality of data samples correspond to a plurality of data subcarriers in the OFDM symbols, and the plurality of pilot samples correspond to a plurality of pilot subcarriers in the OFDM symbols;
- and
- a calculator that calculates an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols, wherein the integer CFO estimate is based on
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230 more elements
An apparatus comprising:
- an estimator including:
- a receiver that receives a plurality of frequency-domain symbols, each symbol including at least one of a plurality of pilot samples and a plurality of data samples;
- a framer that observes the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols, wherein the frequency-domain symbols comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols, the plurality of data samples correspond to a plurality of data subcarriers in the OFDM symbols, and the plurality of pilot samples correspond to a plurality of pilot subcarriers in the OFDM symbols;
- and
- a calculator that calculates an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols, wherein the integer CFO estimate is
- based on
- L
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- where σZ2 is a variance, n represents a subcarrier index offset, k represents a subcarrier index, α represents a ratio of a number of cyclic prefix samples to a number of time domain samples, sp represents a set of indices of pilot subcarriers, sd represents a set of indices of data subcarriers, V is an observation vector, cosh is the hyperbolic cosine function, β represents a boost of pilot subcarrier power, and p represents a predetermined sequence of symbols.
207 more elements
A method of estimating an integer carrier frequency offset (CFO) in a wireless radio-frequency receiver, comprising:
- receiving a plurality of frequency-domain symbols, each symbol including at least one of a plurality of pilot samples and a plurality of data samples, wherein the frequency-domain symbols comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols, the plurality of data samples correspond to a plurality of data subcarriers in the OFDM symbols, and the plurality of pilot samples correspond to a plurality of pilot subcarriers in the OFDM symbols:
- observing the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols;
- and
- calculating an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols, wherein the integer CFO estimate is based
- on
- L
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155 more elements
A method of estimating an integer carrier frequency offset (CFO) in a wireless radio-frequency receiver, comprising:
- receiving a plurality of frequency-domain symbols, each symbol including at least one of a plurality of pilot samples and a plurality of data samples, wherein the frequency-domain symbols comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols, the plurality of data samples correspond to a plurality of data subcarriers in the OFDM symbols, and the plurality of pilot samples correspond to a plurality of pilot subcarriers in the OFDM symbols;
- observing the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols;
- and
- calculating an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols, wherein the integer CFO estimate is based
- on
- L
- ^
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-
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-
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-
-
- {
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-
- ,
-
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-
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- ,
- σZ2 is a variance, n represents a subcarrier index offset, k represents a subcarrier index, α represents a ratio of a number of cyclic prefix samples to a number of time domain samples, sp represents a set of indices of pilot subcarriers, sd represents a set of indices of data subcarriers, V is an observation vector, cosh is the hyperbolic cosine function, p represents a predetermined sequence of symbols, and wd represents a weighting factor.
228 more elements
A method of estimating an integer carrier frequency offset (CFO) in a wireless radio-frequency receiver, comprising:
- receiving a plurality of frequency-domain symbols, each symbol including at least one of a plurality of pilot samples and a plurality of data samples, wherein the frequency-domain symbols comprise Orthogonal Frequency Division Multiplexing (OFDM) symbols, the plurality of data samples correspond to a plurality of data subcarriers in the OFDM symbols, and the plurality of pilot samples correspond to a plurality of pilot subcarriers in the OFDM symbols;
- observing the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols;
- and
- calculating an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols, wherein the integer CFO estimate is based
- on
- L
- ^
- PAE
- =
- arg
-
- n
-
- max
-
- {
- T
- p
-
- (
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- ,
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-
- (
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-
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-
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- ,
- where
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- (
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-
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- where σZ2 is a variance, n represents a subcarrier index offset, k represents a subcarrier index, α represents a ratio of a number of cyclic prefix samples to a number of time domain samples, sp represents a set of indices of pilot subcarriers, sd represents a set of indices of data subcarriers, V is an observation vector, cosh is the hyperbolic cosine function, β represents a boost of pilot subcarrier power, and p represents a predetermined sequence of symbols.
206 more elements
Dependencies are inferred from the claim text.