Multiband and Multibeam Direction of Arrival Estimation Using On-Site Coding Digital Beamformer

Ultrawideband system with digital beamforming allows for spatial filtering and multiuser detection without degradation of the signal-to-noise ratio (SNR). Along these lines, we propose a novel on-site coding receiver (OSCR) architecture for digital beamforming that has already been verified to significantly reduce hardware requirement at the analog back end. Using OSCR, the signal from each antenna element is encoded, then several antenna signals are grouped and digitized using a single analog-todigital converter (ADC). At the digital back end, single field programmable gate arrays (FPGAs) are used for beamforming. In this letter, an 8-channel OSCR is tested for spatial filtering and spectral diversity using a tightly coupled dipole array operating from 290 to 3900 MHz. Measurements were performed in an anechoic chamber using two transmit signals, modulated simultaneously at 1350 and 1800 MHz and arriving from various angles across 0° to ±50°. Results show that an accurate estimate of the angle of arrival is achieved with error <;1.8°. Also, we show that on-site coding has minimal degradation to SNR in a multibeam and multiband environment. Therefore, the proposed architecture is highly suitable for multiple-input-multiple-output (MIMO) applications.