Real time angle of arrival estimation for GSM signals

An FPGA design was created to estimate the angles of arrival for GSM wireless signals in real time. Signals are received using a four element uniform linear array. A wideband IF is undersampled and individual RF channels are tuned digitally. Initially the Blackman-Tukey approach was considered, but ultimately a less complex approach was chosen since it provides suitable performance with fewer multiplication operations. The simpler approach correlates each element with the first element over time. An FFT across the correlation sums estimates the angle of arrival. Estimates are transferred to a PC for analysis and display using a USB interface. This hardware design supports expansion to sixteen elements for real time AoA estimation and beamforming.