Large-System Analysis of MIMO Wire-Tap Channels with Randomly Located Eavesdroppers

Wireless security has become a subject of growing interest in wireless communications due to the broadcast nature of wireless channels. In the present paper, we consider a multiantenna wire-tap channel with randomly distributed eavesdroppers. In the fast fading environment, the overall performance of such channel is characterized by the ergodic secrecy capacity, which, in general, cannot be characterized explicitly. Nevertheless, based on the assumption that the numbers of antennas at legitimate terminals and the number of eavesdroppers grow large without bound, we derive a deterministic approximation for the achievable ergodic secrecy rate. The obtained large-system approximation matches well with the actual simulated secrecy rates, revealing some interesting behavior of the secrecy rates in the given scenario.