In-Band Interference Detection on Reception for IEEE 802.15.4 Transmissions

With the increasing number of wireless devices and competing technologies in overlapping frequency bands an improved spectrum sensing is needed. Todays IEEE 802.15.4 transceiver perform spectrum sensing before transmission. They cannot detect and classify interference during transmission and reception reliably as there is a blind gap during transmission. Strong interference can be detected if bit errors occur. However, the transmission time is a long time interval compared to spectrum/carrier sensing before. In a crowded 2.4GHz ISM band with mobile interfering sources transceivers need continuous spectrum awareness to improve coexistence. In our approach we extend the physical layer (PHY) of a traditional receiver with additional signal processing. We perform signal analysis with Fourier transform of a demodulated signal to detect interferer during reception before bit errors or collisions occur. We implement our algorithm with a software defined radio as an extension of the physical layer (PHY) of an IEEE 802.15.4 transceiver. We evaluate our approach with measurements and detect mobile interferers in a real world environment. We discuss the design space of solutions as a trade-off between the quality of interference detection and the time for detection.