Performance analysis for direction finding in non-Gaussian noise

We consider narrowband angle of arrival estimation in non-Gaussian (NG) noise channels, such as arises in some indoor and outdoor mobile communications channels. We develop a general expression for the Cramer-Rao bound (CRB) for direction finding using arrays for deterministic signals plus i.i.d. non-Gaussian noise, generalizing the Gaussian CRB. The CRBs for the noise and direction parameters decouple. The CRB for direction finding is expressed as a product of two terms that depend on the noise distribution, and the signal, respectively. We illustrate the results for a Gaussian mixture PDF, and present simulation results comparing five direction finding algorithms. An approach based on the expectation-maximization (EM) algorithm, that simultaneously estimates the noise parameters, the signal directions, and the signal waveforms, is shown to achieve the CRB over a wide SNR range.