An Orthogonal Relay Protocol with Improved Diversity-Multiplexing Tradeoff

The maximum multiplexing gain of orthogonal relaying protocols has, so far, been limited to 1/2. We propose a new orthogonal decode-and-forward protocol that employs rotated n-dimensional constellations. With a single relay, the proposed protocol achieves a linear diversity-multiplexing tradeoff (DMT) connecting the points (0,2) and (n/n+1,0), where n+1 is the frame length. With N_R relays, our proposed protocol achieves a linear DMT connecting (0, N_R+1) and (n/n+N_R,0).