Project CharIoT: Cross Technology Distributed MIMO for Low Power IoT

The Internet of Things (IoT) is scaling rapidly to billions of low power devices, with diverse radio technologies sharing a common unlicensed spectrum. Inevitably, this results in rampant cross-technology collisions between the devices that lead to wasteful re-transmissions, draining the battery life of low-power devices significantly. We present CharIoT, the first cross-technology distributed MIMO receiver system that exploits the potential of distributed MIMO to facilitate better co-existence and decoding of a large number of simultaneous low power uplink transmissions from unmodified low-power clients. CharIoT is a recovery-based system that intelligently collects radio samples from teams of light-weight IoT gateways and streams them to the cloud to effectively resolve collisions. At the cloud, CharIoT develops a suite of technology-specific software filters that decouple collisions across diverse technologies, facilitating seamless co-existence across low power radios. An implementation of CharIoT on inexpensive RTL-SDR gateways connected to a Raspberry Pi decodes collisions of four popular IoT technologies in the 868MHz ISM bands - LoRa, XBee, Z-Wave and SIGFOX showing gains in throughput of up to 4x and battery life of up to 3.5 years.


  • Cross Technology Distributed MIMO for Low Power IoT, Revathy Narayanan, Swarun Kumar and C. Siva Ram Murthy, IEEE Transactions on Mobile Computing 2020