Energy-efficiency and spectrum-efficiency tradeoff in coordinated small-cell networks

Small-cell networks play an important role in next generation mobile networks. Multiple antennas can be employed at the small-cell base stations (SBS) to further improve the spectrum-efficiency. However, the increased number of antenna elements induces more energy consumption, i.e., there exists a tradeoff between the energy-efficiency and the spectrum-efficiency. In this paper, the network performance is analyzed which takes the coordinated scheduling into account. The coordination relationship among neighboring SBSs is modeled by a coordination graph. The coordinated scheduling is achieved by finding the maximum independent set of the graph. By deriving the average size of the maximum independent set, the network throughput is obtained. Simulation results validate the derivation. Then, the tradeoff between the energy-efficiency and the spectrum-efficiency is analyzed. It is found that the single-antenna SBSs are not energy-efficiency as the density of SBSs increases.