Secondary user access for IoT applications in the FM radio band using FS-FBMC

In this paper a Dynamic Spectrum Access (DSA) Physical layer (PHY) technique is proposed that allows Secondary User (SU) access to the traditional FM Radio spectrum (88-108 MHz) for alternative data communication applications. FM radio waves have excellent propagation characteristics for long distance transmission, and have high levels of penetration through buildings. Using tools such as a structured geolocation database of licensed Primary User (PU) FM Radio transmitters, unlicensed SUs can access portions of the 20 MHz-wide band and transmit signals that place spectral ‘holes’ with suitable guard bands around all known PUs. Based on the PU protection ratios published by Ofcom and the FCC, the operation of a FBMC (Filter Bank Multi-Carrier) transmitter is demonstrated for an urban environment, and through ‘field test’ simulation it is shown that the Out Of Band (OOB) leakage of the proposed PHY (energy in the ‘holes’ that can interfere with the PU) is 47 dB lower than that of using an equivalent OFDM PHY. The results show that the proposed PHY is a suitable candidate for DSA-SU communication (e.g. in smart city IoT applications), whilst ensuring the integrity of incumbent PU signals.