A General Framework for Spectral Efficiency, Energy Efficiency and Delay Tradeoff in D2D Networks

In this paper, we propose a novel framework to investigate the three-factor tradeoff among spectral efficiency (SE), energy efficiency (EE) and delay in D2D communications underlaying cellular networks. Taking both channel state information and queue state information into account, a stochastic multi-objective optimization problem is formulated aiming at maximizing SE and EE simultaneously subject to the queue stability constraint, where subchannel allocation and power optimization are jointly considered. The single-objective optimization problem is then derived with the help of weighted sum method and Lyapunov techniques, where an effective algorithm is designed to achieve the three-factor tradeoff among SE, EE and delay. Afterwards, the optimal subchannel and power allocation is obtained via the Lagrangian dual decomposition method, which only requires polynomial computational complexity. Both in-depth theoretical analysis and simulation results verify that the proposed algorithm enables the system controller to comprehensively balance the three-factor tradeoff among SE, EE and delay by flexibly adjusting two introduced weighting parameters.