RIA: An RF Intereference Avoidance Algorithm for Heteregeneous Wireless Networks

Due to the unlicensed nature of 2.4 GHz ISM band, the number of technologies using this band is growing. FCC regulations mandate that these technologies need to implement some form of frequency sharing. Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS) are two popular techniques to share the frequencies within this band. However, devices implementing different technologies may cause interference; this problem is well-documented as occurring with 802.11 (using DSSS) and Bluetooth (using FHSS). Designing an interference avoidance algorithm for combinations of these DSSS/FHSS based technologies is complex. In this paper, we focus on a simpler but very common case when these technologies are located within the same device. For this case, we propose a simple and novel algorithm called, Radio Interference Avoidance Algorithm, RIA, that solves the problem of interference between any arbitrary DSSS and FHSS technologies. In this paper we derive the expected value of response time for RIA. We then run simulations to demonstrate the effectiveness of RIA. Our results indicate that RIA is able to eliminate interference with a very small response time. RIA also outperforms Adaptive Frequency Hopping, a solution proposed by the IEEE 802.15 Co-existence Working Group.