On the Efficacy of Frequency Hopping in Coping with Jamming Attacks in 802.11 Networks

Frequency hopping (FH) has been the most popularly considered approach for alleviating the effects of jamming attacks. We re-examine, the efficacy of FH based on both experimentation and analysis. Briefly, the limitations of FH are: (a) the energy spill over between adjacent channels that are considered to be orthogonal, and (b) the small number of available orthogonal bands. In a nutshell, the main contributions of our work are: (a) Construction of a measurement-driven game theoretic framework which models the interactions between a jammer and a communication link employing FH. Our model accounts for the above limiting factors and provides bounds on the performance of proactive FH in coping with jamming. (b) Extensive experimentation to quantify the impact of a jammer on 802.11a/g/n networks. Interestingly, we find that 802.11n devices can be more vulnerable to jamming as compared with legacy devices. We carefully analyze the reasons behind this observation. (c) Application of our framework to quantify the efficacy of proactive FH and validation of our analytical bounds across various 802.11 network configurations. (d) Formal derivation of the optimal strategies for both the link and the jammer in 802.11 networks. Our results demonstrate that FH seems to be inadequate in coping with jamming attacks in current 802.11 networks.