Amplify-and-Forward Cooperative Communications Using Double-Differential Modulation over Nakagami-m Channels

In this paper, we propose double-differential (DD) modulation for an amplify-and-forward protocol based on cooperative communication over Nakagami-m fading channels. The proposed scheme is able to achieve performance gain in the presence of random carrier offsets and without channel knowledge at relay or destination. The proposed scheme reflects its utility for the Nakagami-m type flat fading channels with carrier offsets, where the conventional single differential scheme breaks down. In addition, the proposed scheme outperforms the conventional direct transmission double-differential system.