Energy conservation and interference mitigation: From decoupling property to win-win strategy

This paper studies the problem of conserving the energy of mobile terminals in a multi-cell TDMA networks supporting bursty real-time sessions. The associated optimization problem involves joint scheduling, rate control, and power control. To tackle the complexity, we propose a decomposition method that decouples the overall problem into two sub-problems: intra-cell energy optimization and inter-cell interference control. This decomposition results in a “win-win” situation: it reduces the energy consumptions and inter-cell interference at the same time. Simulations show that our decomposition method can achieve an energy reduction of more than 70% compared to the simplistic maximum transmit power policy. It can achieve an energy reduction of more than 50% compared to the case where only intra-cell energy optimal transmission is performed. We also derive an interesting decoupling property assuming that the interference power stays constant over a TDMA frame: if the idle power consumption of mobile terminals is no less than their circuit power consumption during transmission, or when both are negligible, then the energy-optimal transmission rates of the mobile terminals are independent of the inter-cell interference power level.