An Adaptive MIMO-OFDMA Relay System

We consider multi-input multi-output (MIMO) antennas relay systems under time-varying channels and propose a joint relay, antenna, subband, and MIMO transmission mode adaptation scheme which enables antenna selection to exploit channel state information (CSI) at the beginning of transmission and switch to space-frequency block coding (SFBC) when CSI becomes outdated. Moreover, we propose temporal power and bit loading for the cascaded source-relay-destination link with/without inter-hop power allocation to further enhance the system performance.