Energy reduction in small cell networks by a random on/off strategy

Data applications can tolerate an initial delay before packet transmission begins. It is possible to take advantage of this initial delay to reduce the energy required to operate the small access points (SAPs) and decrease transmission power in small cell networks. To demonstrate the trade-off between delay and transmit power, we consider a simple access scheme and analyze the distribution of the user equipment's (UE's) transmit distance. In the demonstration, there are a sufficient number of small cells to handle the peak traffic load. In order to reduce average power consumption, a number of SAPs are turned off during lower demands. The power consumption can be reduced further by turning all of the SAPs on and off, rather than selecting a subset and leaving them off. Since many SAPs are turned off at low traffic profile, UEs may be able to save energy by delaying their transmissions and waiting for a closer SAP to become available, thereby reducing transmission power. We analyze energy-efficiency versus delay trade-off, investigate optimality conditions for UE's transmit power and verify our analytical results via simulations. Results show that i) Instead of turning SAPs off for a long period, turning them on and off continuously and taking advantage of initial delay to connect a c yield an order of magnitude reductions in the transmit power, and ii) reduces the mean power consumption of SAP.