  This paper addresses the establishment of secure communication links between
smart-meters (Alice) and an aggregator (Bob) in the presence of an eavesdropper
(Eve). The proposed scenario assumes: (i) MIMOME wiretap channel; (ii) transmit
antenna selection at the Alice; (iii) no channel state information at the
transmitter; (iv) fixed Wyner codes; and (v) guarantee of secure throughput by
both quality of service and secrecy outage constraints. We propose a simple
protocol to enhance security via transmit antenna selection, and then assess
its performance in closed-form by means of secrecy outage and successful
transmission probabilities. We assume these probabilities are our constraints
and then maximize the secure throughput, establishing a security-reliability
trade-off for the proposed scenario. Our numerical results illustrate the
effect of this trade-off on the secure throughput as well as on the number of
antennas at Alice, Bob and Eve. Interestingly, a small sacrifice in reliability
allows secrecy enhancement in terms of secure bps/Hz. We apply this idea in our
smart grid application to exemplify that, although Eve may acquire some samples
of the average power demand of a household, it is not enough to properly
reconstruct such curve.
