DREW: Double-Throughput Emulated WiFi

WiFi access points (APs) combines the benefits of long battery life, low device cost, and ubiquitous Internet access. However, prior cross-technology communication (CTC) solutions require transmission mixers inside FSK chips, thus not applicable to newer ultra-low-power (ULP) BLE chips, which removes these mixers to conserve power. Furthermore, throughputs of prior CTC solutions are limited to 1Mbps.

We present DREW that fundamentally overcomes these limitations. It is designed to effectively transmit WiFi packets by only controlling the power amplifier (PA), and is thus applicable to mixer-less ULP BLE chips. We also propose an innovative use of BLE's IQ sampling capability to receive standard WiFi packets. We design efficient algorithms with SIMD (Single Instruction Multiple Data) acceleration to detect, synchronize and demodulate WiFi packets from IQ samples in real time. DREW also implements WiFi's CS-MA/CA and timing, thus adding direct WiFi connectivity to ULP BLE devices. Unlike prior work, DREW uniquely supports QPSK and therefore doubles the downlink throughput. This 2x throughput increase is crucial for new applications that prior work cannot support. In particular, DREW can stream lossless, HiFi-quality audio from WiFi to ULP BLE chips. Since stereo audio requires a throughput of 1.411Mbps, no prior work can support this important application due to their 1Mbps limitation.