“…We build an end-to-end prototype for LLOCUS, that uses a cloudbased compute server as the CC, with a web interface for sending commands to the crowdsourced participants. For the convenience of the participants, instead of the tethered RTL-SDR that we used for collecting dataset A, B, and C, we use a low-power, portable, and untethered SDR, that we have developed [14], with both RF transmit and receive capability, as the crowdsourced client. We build an Android app that runs on the participants' smartphones in the background, and simultaneously maintains a socket with the CC and a Bluetooth connection to the SDR; thus it acts as an intermediary between the CC and the SDRs.…”