Tradeoff between energy efficiency and queues delay in heterogeneous cloud radio access networks

The dynamic stochastic resource optimization problem in heterogeneous cloud radio access networks (H-CRANs) is researched in this paper, characterizing the cooperative beamforming with fronthaul capacity and queue stability constraints. To make the average energy efficiency (EE) of remote radio heads (RRHs) arbitrarily close to the optimum and maintain system queue stability, the EE optimization problem considering congestion control is presented. Under the Lyapunov framework, the problem is reformulated as an optimal network-wide beamformer design of RRHs, which is solved through a generalized weighted minimum mean square error (WMMSE) approach. The mathematical analysis and simulation results demonstrate that an EE-delay tradeoff can be achieved by the proposed algorithm.