Energy-Efficient Cross-Layer Design of Delay-Aware MIMO Systems

In this paper, we propose a cross-layer design model for multiple input and multiple output (MIMO) cellular systems, to solve the problem of energy efficient communications with delay demand. We first investigate the energy efficient multiple quadrature amplitude modulation (MQAM) constellation size for each transmission stream. With the demand of the packet delay, then we propose an adaptive MIMO/SIMO transmission mode by exploiting the intrinsic relationship between the upper layer packet delay and the constellation size, the symbol error rate (SER) from the physical layer. Simulations show that in order to maximize the energy efficiency and offer different Quality of Service (QoS) of delay simultaneously, a user should adaptively choose the constellation size as well as the transmission mode. In this framework, the tradeoff between energy efficiency and delay demand are well demonstrated.