Carrier frequency and direction of arrival estimation with nested sub-nyquist sensor array receiver

Carrier frequency and its corresponding direction of arrival (DOA) estimation, at sub-Nyquist sampling rates of narrowband (bandwidth not exceeding B Hz) sources is considered in this paper. We assume M physical sensors arranged in a two dimensional nested sensor array configuration and propose to modify the receiver architecture by inserting an additional delay channel to only the dense sensor array. An efficient subspace based estimation algorithm to estimate the carrier frequencies and their DOAs is also presented. With this proposed approach we show that a minimum ADC sampling frequency of B Hz is sufficient and O(\M/4]2) carrier frequencies and their DOAs can be estimated despite all the carrier frequencies exactly aliased to the same frequency. Furthermore, simulations indicate that when used for spectrum estimation, in addition to carrier frequencies and their DOA estimation, it shows better performance compared to an existing approach using the same M element uniform two dimensional sensor array.