Spectral-energy efficiency tradeoff in multicell cellular networks with adaptive relay cooperation

By observing that the relay stations (RSs) will receive a signal replica of the users´ transmissions during the broadcast phase, we propose an adaptive relay cooperation scheme. The RSs will utilize the readily available signal replica and the additional diversity naturally inherent in them to either perform cooperative multipoint (COMP) relaying or remain silent with only the direct transmission being considered. We investigate this scheme in a 7 cell network to demonstrate system level capacity and energy efficiency improvements. Results show that the proposed scheme outperforms the conventional adaptive relay scheme and is able to benefit from the more aggressive full bandwidth frequency reuse plan at low relay transmit power.