Patent ID: 8576963

Claim:
A non-coherent detection apparatus comprising: a correlation unit obtaining a differential phase signal by multiplying a complex conjugate value of a delay signal that is obtained by delaying a received signal by (N+1) chips (N corresponds to a length of a pseudorandom number (PN) code) by the received signal, summing-up resultant values that are obtained by multiplying each component of the differential phase signal by each component of a correlation sequence corresponding to the received signal and outputting a correlation signal; a frequency offset estimator estimating a frequency offset based on a value that is obtained by accumulatively summing-up the correlation signals corresponding to preamble portions of the received signal from among the correlation signals; and a signal detector detecting an original signal from the received signal based on a size of a real-number part of a resultant value that is obtained by multiplying the frequency offset estimated by the frequency offset estimator by the correlation signal corresponding to a PHY payload portion of the received signal from among the correlation signals, wherein the frequency offset estimator estimates the frequency offset from a whole preamble of the received signal by using the following Equation C: Y 1 = ⁢ 1 ( J - 1 ) ⁢ N - 1 ⁢ { ∑ m = 2 J - 1 ⁢ ∑ k = 0 N - 1 ⁢ p ⁡ [ Nm + k ] ⁢ p * [ Nm - ( N + 1 ) + ⁢ k ] ⁢ b m ⁡ [ k ] + ∑ k = 1 N - 1 ⁢ p ⁡ [ N + k ] ⁢ p * ⁡ [ k - 1 ] ⁢ b 1 ⁡ [ k ] } = ⁢ ⅇ j ⁡ ( N + 1 ) ⁢ ω 0 ⁢ T c + η 5 , ( C ) where, Y 1 is the frequency offset, p[n] is a preamble signal received at time 0, J is a bit number of the preamble signal p[n], N is a length of the PN code, b m [k] is a k-th component of the correlation sequence with respect to the m-th bit of the PPDU, ω 0 is a carrier wave frequency offset, T c is a duration of a chip, and η 5 is a noise component.