Research On The DME Interference Mitigation Based On Compressive Sensing For OFDM Receiver

L-Band Digital Aeronautical Communication System1(L-DACS1) is an air-ground cellular communication system based on Orthogonal Frequency Division Multiplexing(OFDM), and provides communication services for Air Traffic Services(ATS) and Aviation Operation Control(AOC). As an inlay system, L-DACS1 was deployed in the spectral gaps between two adjacent channels of Distance Measure Equipment(DME), which was approved by the World Radio Conference in 2007. To mitigate the deleterious influence of DME interference on OFDM receiver of L-DACS1 system, DME pulse interference suppression researches have been carried out based on compressed sensing. The main research contents of this paper are as follows:Firstly, conventional pulse interference suppression methods of OFDM receiver are researched. The principle and signal mode of DME system are described. Then DME interference impact on L-DACS1 system is modeled and analyzed. Furthermore two conventional pulse interference suppression methods are introduced, including pulse blanking and pulse clipping. Finally the impact on bit error rate of L-DACS1 system from DME and anti-interference performance of conventional pulse interference suppression method are researched by simulation.Secondly, basic theory of compressed sensing is study. The outline of compressed sensing is described. Then the compressed sensing algorithms are derived in detail, including sparse representation of signal, selection of measurement matrix and reconstruction algorithms. Finally the effect of sparse signal reconstruction based on compressive sensing theory is researched by simulation.Thirdly, A DME pulse interference mitigation method based on joint compressed sensing and whitening of residual interference is proposed. DME pulse interference is observed via null sub-channels of the OFDM receiver and reconstructed with compressed sensing method based on the sparse characteristic of the DME pulse interference in time domain. Then the reconstructed DME pulse interference is transformed to frequency domain and eliminated from the received signal. Finally, to avoid burst errors of demodulator, the residual pulseinterference is whitened by using the de-interleaver and inverse orthogonal transformer. The computer simulation indicates that the proposed method can reduce the impact of DME interference effectively, and improve the reliability of OFDM receiver of the L-DACS1 system significantly.