Layered sources in non-orthogonal amplify-forward relay networks

In this paper, we consider broadcasting layered source codes over a single-relay network using a half duplex non-orthogonal amplify-forward (HD-NAF) relaying protocol. Distortion exponent (i.e., the SNR exponent of the average distortion) is taken to evaluate the system performance in the high SNR regime. We prove that the HD-NAF relay network with two-layered codes corresponds to a successive refinable diversity multiplexing tradeoff (DMT) curve.With the identified property, a closed-form expression for an achievable upper bound of the system distortion exponent is derived, which can be achieved via properly allocated power and rate of each layer. Numerical evaluation is conducted to show performance advantages of the considered two-layered HD-NAF protocol against its counterparts.