Long-range body-to-body LoRa link at 868 MHz

In the context of the Internet of Things, LoRa is an important standard for low-power wide area sensor networks. LoRa communication employs chirp spread spectrum modulation in sub-GHz frequency bands, combining the benefits of both to enable low-power kilometer-range wireless data communication. LoRa modulation provides a high link budget and additionally, sub-GHz bands possess excellent radio propagation characteristics. A LoRa transceiver was integrated onto a textile substrate-integrated-waveguide antenna in order to set up long-range body-to-body communication links. The unit is a fully autonomous wearable wireless sensor node, including a transceiver, processor, sensors, flash memory and a low profile battery, all integrated on the feed plane of a textile antenna. The design and characteristics of the unit are described, including radiation patterns of the fully assembled unit. Finally, an outdoor long-range performance test is performed as a proof of concept. Communication was reliable for a range over 500 m and over 200 m with the antennas pointed towards and away from each other, respectively. In static conditions, a range of 1.44 km was observed.