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For the problem of Direct Sequence spread spectrum unbalance Quadrature Phase Shift Keying (DSSS/UQPSK) signal can't be detected easily, the method of the fourth-order cumulant detection is proposed in this paper. On the basis of the fourth-order cumulant of the Gaussian White Noise is equal to zero, Firstly, the paper analyzes the theory knowledge of direct sequence unbalance QPSK signal and the...
For the blind estimation problem of period of the PN (Pseudo Noise) code and the combination code (combination of spread spectrum sequence and subcarrier sequence) in BOC (Binary Offset Carrier) signal with the residual carrier in the low SNR (signal-to-noise ratio), the method which combines the reprocessing of the power spectral density with matrix decomposition is developed. Firstly, the reprocessing...
As a key point of orthogonal frequency division multiplexing (OFDM) technology, carrier frequency offset (CFO) has a significant effect on OFDM system performance. This paper proposes a CFO estimation method by using complementary sequence (CS) as training sequence. The proposed CS-based method can operate integer CFO and fractional CFO estimations on the basis of the same training sequence. The fractional...
Owing to the frequency-selective fading channel with a carrier frequency of OFDM (orthogonal frequency division multiplexing) signal to noise ratio (SNR) estimation problem, we proposed SNR blind estimation method based on air carrier OFDM system. Due to the inconsistency between the oscillator and the received signal, the received signal will be with a certain deviation. The presence of frequency...
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