HR contacted after a few days of applying. 1 hour virtual video interview with one of their principal engineers was initially setup. 6 45-min final round technical interviews (all virtual and back-to-back), which also included a 30-min presentation on my background. Questions were all on the theoretical side. People need to brush up on DSP and Digital Communications and be prepared to derive equations on the fly. Most interviewers were friendly, but I got completely ghosted after the final round. I reached out to HR 3 weeks afterwards, and never got a response, which is extremely unprofessional.