A WiFi and Bluetooth Backscattering Combo Chip Featuring Beam Steering via a Fully-Reflective Phased-Controlled Multi-Antenna Termination Technique Enabling Operation Over 56 Meters

Abstract

Many envisioned IoT applications are not realizable today due to the mW-level power burden of wireless communication circuits for the most popular consumer standards: WiFi and BLE. To help enable new IoT applications, WiFi backscatter communication techniques have been shown to enable a ∼1, 000× reduction in power consumption over conventional transceivers while maintaining WiFi standard compatibility [1]–[3]. However, pragmatic deployment is currently hindered by their limited range, and lack of IC implementations for BLE [4]–[5]. For example, [3] and [1] only operate with inter- access point (AP) distances of 16m and 21m, respectively, which is not quite sufficient for robust operation in dense office environments, or large smart warehouses or airports with larger (and therefore lower cost) inter-AP deployment distances. Since backscatter modulation is passive with no RF power amplification, additional range can only be achieved by reducing insertion loss or adding antenna gain. For example, the work in [2] replaced 500 absorbing terminations with reactive terminations to reduce insertion loss over [1] and improve range to 26m, though a bulky and lossy Wilkinson power splitter/combiner was still required. The work in [2] also introduced a way to utilize multiple antennas to achieve MIMO-like antenna gain, though only in a static retro-reflective manner with no beam steering capabilities. This latter approach requires two co-located APs, which have self-interference challenges, and are thus not readily available in existing mesh networks. In addition to range challenges, there are no current backscatter ICs that can operate with BLE.