STB-SASB: Combining Synthetic Aperture Sequential Beamforming with Synthetic Transmit Beams for Wireless Ultrasound Probes

Wireless ultrasound probes typically perform beamforming on the probe and communicate B-mode images to meet bandwidth constraints of wireless links. Performing on-probe beamforming is thermally-bound, hence wireless probes typically only provide limited capabilities compared to cart-based systems.In this work, we apply Synthetic Aperture Sequential Beamforming (SASB) to enable beamforming "after" the wireless link, i.e., on the mobile device connected with the wireless probe. SASB enables wireless transmission of the data by performing only simple operations on the probe. The compute-intensive part of the image formation is performed on the connecting device. However, SASB consumes much energy in the analog front-end compared to other methods such as diverging beams imaging.In this paper, we present the first (to the best of our knowledge) working prototype of a 64-channel wireless ultrasound probe performing SASB. The prototype allows comparing the energy-consumption and image quality of SASB with other methods. To improve the energy-consumption, we propose STB-SASB, a combination of SASB with synthetic transmit beams (STB). STB-SASB with two synthetic beams reduces the front-end consumption by 50% with ideal power management. On our system, we demonstrate savings of 31% with a minor quality degradation of 6% in resolution (FWHM). More synthetic beams reduce the consumption even further at the cost of quality.