CHAPTER 6 Robust Wireless Infrastructure against Jamming Attacks 143 6. Considering the setup of the previous exercise, what keys should be assigned to node 9? 7. Consider the PBK-T scheme described in Sec- tion 6.4.1. In the presence of insider attackers, what is the average number of periods needed to deliver a broadcast message (i.e., expected delay)? Discuss both the cases where the num- ber of insider attackers are both below and above the threshold T . 8. Consider the packet size game described in Section 6.5 (Table 6-5). Find the Nash Equi- librium when parameter A is set to 2500. Keep the communicating nodes strategies fixed to packet sizes 500 and 1000 bytes, and the jammer rates at 250 and 1000 pulses/s. [7] [8] [9] REFERENCES [1] W. Xu, W. Trappe, Y. Zhang, Defending wireless the 27th annual joint conference of the IEEE Computer and Communications Societies (INFOCOM 2008), INFOCOM'08, IEEE Press, Piscataway, NJ, 2008, pp. 1211­1219. K. Pelechrinis, I. Broustis, S.V. Krishnamurthy, C. Gkantsidis, Ares: An anti-jamming reinforcement system for 802.11 networks, in: Proceedings of the 5th international conference on emerging networking experiments and technologies, CoNEXT '09, ACM, New York, 2009, pp. 181­192, http://doi.acm.org/10.1145/1658939.1658960. K. Pelechrinis, C. Koufogiannakis, S.V. Krishnamurthy, Gaming the jammer: Is frequency hopping effective? in: Proceedings of the 7th international conference on modeling and optimization in mobile, ad hoc, and wireless networks, WiOPT'09, IEEE Press, Piscataway, NJ, 2009, pp. 187­196, http://portal.acm.org/ citation.cfm?id=1715782.1715816. B. Awerbuch, A. Richa, C. Scheideler, A jamming-resistant mac protocol for single-hop wireless networks, in: Proceedings of the 27th ACM symposium on principles of distributed computing, PODC '08, ACM, New York, NY, USA, 2008,