On the Location of an Eavesdropper in Multiterminal Networks

We study the optimum location of an eavesdropper from a secrecy capacity perspective in multiterminal networks with power control. We determine the logical location of an eavesdropper (represented by the channel gain from all the transmitters) which 1) results in zero secrecy capacity for maximum number of users in the network and 2) results in zero secrecy capacity for the bottle-neck links. We then analyze the asymptotic secrecy capacity of the system and the asymptotic behavior of the optimum logical location of the eavesdropper. Results indicate that power control can make eavesdropping more difficult as it results in infeasible locations for the eavesdropper. Power control is also shown to provide scenarios which can result in positive asymptotic secrecy capacity for all the users.