Trade-Offs on Energy-Efficient Relay Deployment in Cellular Networks

Relay-based cellular networks are likely to play an important role in the race for energy efficiency. However, potential gains greatly depend on how relay stations are deployed within the cell. Using a geometrical model for energy-efficient analysis, we investigate the impact of the number and location of relays on energy consumption, and its dependence on the relay coding scheme and the propagation environment, i.e. the pathloss and the line-of-sight conditions. In addition to the transmit energy, we account for the economic cost of relay deployment, as well as the overhead energy dissipated at each relay stations due to data processing and network maintenance. We then bring out four key trade-offs which balance the cost and flexibility of relay deployment, the energy efficiency and the coverage extension.