Opportunistic orthogonal writing on dirty paper

Consider the problem of precoding for the infinite-bandwidth Costa's dirty-paper channel. We propose a simple opportunistic orthogonal signaling scheme that achieves both the minimum energy per bit for reliable communication and the reliability function of the channel. We show that a simple extension of this scheme achieves the minimum energy per bit for the infinite-bandwidth "dirty-paper" channel with i.i.d. non-Gaussian dirt.