Patent ID: 8009768

Claim:
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 ^ PAE = argmax n ⁢ { T p ⁡ ( n ) + T d ⁡ ( n ) } , where T p ⁡ ( n ) = ⁢ { ⅇ - j ⁢ ⁢ 2 ⁢ π ⁢ ⁢ na ⁢ ∑ k ∈ S p ⁢ V ⁡ [ k + n ] ⁢ p * ⁡ [ k ] } , T d ⁡ ( n ) = ⁢ σ Z 2 ⁢ ∑ k ∈ S d ⁢ log ⁡ ( 2 ⁢ ⁢ cosh ⁡ ( ⁢ { V ⁡ [ k + n ] ⁢ ⅇ - j ⁢ ⁢ 2 ⁢ π ⁢ ⁢ na } σ Z 2 ) + 2 ⁢ ⁢ cosh ⁡ ( ⁢ { V ⁡ [ k + n ] ⁢ ⅇ - j ⁢ ⁢ 2 ⁢ π ⁢ ⁢ na } σ Z 2 ) ) , σ Z 2 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, s p represents a set of indices of pilot subcarriers, s d represents a set of indices of data subcarriers, V is an observation vector, cosh is the hyperbolic cosine function, and p represents a predetermined sequence of symbols.