Angle of Arrival Estimation Method Based on SNR Threshold Detection and Data Cache

The angle of arrival (AOA) measurement of the received signal is an important technology for phased array radar and communication system. Traditionally, it can be estimated from the maximum value which is calculated by differentials of the sum and difference beams. The Fast Fourier Transform (FFT) technique can be used to generate the sum and difference beams which can reduce complexity of beam-forming. However, the accuracy of AOA estimation will be decreased by the fluctuation signal-to-noise ratio(SNR) of arrived signal. To avoid the unsuccessful AOA estimation caused by the influence of SNR, a method of AOA estimation based on SNR threshold detection and channel data cache is introduced in this paper. When the SNR of the received signal exceeds the detection threshold, the original channel data at that moment is written to the cache. The AOA result can be estimated from the sum and difference beams which is calculated by accumulated data in cache. Beam domain interpolation is used to increase the number of beams which can enhance the accuracy of AOA estimation. In order to find the the appropriate accumulation length, the relationship between FFT length and AOA measurement accuracy is simulated. The improvement of AOA accuracy is compared between spatial domain accumulation and beam domain accumulation and spatial domain accumulation is proved to have better performance on the condition of same SNR and FFT length. Finally, the OFDM signal with large peak-to-average power ratio (PAPR) is used to verify the effectiveness of the method on the condition of SNR fluctuation.