Performance analysis of four different downlink data relaying schemes in cellular systems

In this paper, we mathematically analyze the performance of four different relaying schemes in cellular systems. We assume a downlink cellular system with fixed relays and a mobile station is either directly connected to a base station and/or connected to a relay station. We consider four different downlink data relaying schemes: a direct scheme, a relay scheme, a selection scheme, and a cooperative scheme. Under the environment, we derive a closed-form solution or upper bound of the ergodic and outage capacities. We also analyze the system capacity in a multiuser diversity environment in which a maximum signal-to-noise ratio (SNR) scheduler is used at a base station. The analytical results agree well with computer simulation results. The result shows that the selection scheme outperforms the other three schemes in terms of link ergodic capacity, link outage capacity, and system ergodic capacity.