Event Based Frequency Agile Mechanism For IEEE 802.15.4 Interference Avoidance

Abstract: Frequency hopping is one of the most successful solutions to the issues of interference and coexistence facing wireless devices that utilize the unlicensed 2.4GHz ISM band. However, the current scheme is based on Bluetooth frequency hopping mechanism and was designed to be implemented on capable devices that are “not” characterized by limited computational power and resources. In this work we propose a new frequency hopping technique primarily for use with low cost, IEEE 802.15.4 compliant devices that can be employed in wireless sensor networks. Unlike the frequency hopping scheme developed for Bluetooth, WirelessHART and ISA-100.11a, the proposed solution is event driven, thus allowing the network to change its operating frequency in the face of interference once problems are sensed in the channel without the need for extra computational and extensive scheduling activities.  The design of the proposed algorithm was carried out using specification and description language (SDL)and the simulation of the SDL model revealed promising results. The proposed algorithm is then implemented on an IEEE 802.15.4 stack that was developed in NesC and TinyOS and is implemented on Micaz motes.