Precoded modulations for outage probability minimization on block fading channels

We study precoded modulations for the outage probability minimization of block fading channels. This paper establishes interesting upper bounds on the outage probability, whose simple expressions allow to determine which precoding matrix minimizes these upper bounds. Through this optimization, the gap between the outage probability corresponding with a discrete input alphabet and the best outage achieved by an i.i.d. Gaussian alphabet is almost closed.