High Sensitivity RF Transceiver for Long Range IoT Communications

This paper presents the architecture, the realization and the measurement results of a high sensitivity, long range and low data rates radio frequency (RF) transceiver. The transceiver can be used for Wireless Sensor Networks or Internet of Things (IoT) applications as well as for any long range digital point to point RF links. The system is designed for the 869 MHz Industrial, Scientific and Medical (ISM) frequency band. For Minimum Shift Key (MSK) modulation and data rate of 500 bit/s the measured receiver sensitivity is −134 dBm. A sensitivity improvement can be achieved by using the Time Synchronous Averaging (TSA) method. In this approach the block to be sent is retransmitted multiple times. Received blocks are synchronously averaged thus increasing the signal-to-noise ratio. By retransmitting the data block 3 times the sensitivity is increased by 3 dB. For a transmitted power of 19 dBm a radio link can be achieved over a distance of more than 11 km with a standard whip antenna.