Research On Oblique Projection Based Phase Noise Suppression For Ofdm Systems

In the Orthogonal Frequency Division Multiplexing (OFDM) systems, the phase noise which leads to the common phase error (CPE) and the inter-carrier-interference (ICI), destroys the orthogonality of the sub-carriers and causes considerably significant performance degradation of the bit-error rate (BER) and the signal-to-interference-and-noise ratio (SINR).In order to suppress the CPE and the ICI for OFDM systems, a novel blind adaptive suppression scheme based on the oblique projection theory is proposed in this paper. By introducing the oblique subspace method, we establish the linear subspace model for OFDM systems, and show that the augmented matrix operation of the signal subspace and the interference subspace (phase noise subspace) can be adopted to satisfy the condition of full column rank for constructing the oblique projection operator to eliminate the CPE and the ICI, therein, the signal subspace can be achieved by sending the pilot data sequences.The proposed oblique projection phase noise suppression (OPPNS) algorithm can be implemented by calculating the second-order statistics of the received signal, estimating the signal subspace and the power spectral density of the AWGN, respectively. Theoretical analysis and the mathematical deduction show that the phase noise can be eliminated effectively without the knowledge of itself, which can reduce the system complexity and achieve a blind adaptive processing. It is demonstrated that the BER and the SINR performance of the proposed OPPNS outperforms the conventional common phase error cancelation (CPEC) method when adopting the IEEE 802.11a standard as the simulation environment.