On energy-delay tradeoff in base station sleep mode operation

Base station (BS) sleep mode operation is one of the effective ways to save energy, but it may lead to longer delay to the customers. In order to evaluate the tradeoffs between energy consumption and customer delay, we model the BS sleep mode operation as an N-policy M/G/1 vacation queue with setup and close-down times, where the BS enters sleep mode if no customers arrive during the close-down time after the queue becomes empty and it starts to setup when it sees N customer arrivals during its sleep period. Several closed-form formulas are derived to demonstrate the tradeoffs between energy consumption and mean delay by changing the close-down time and N. It is shown that the relationship between the energy consumption and the mean delay is linear by changing the close-down time. Besides, larger N reduces the energy consumption, but there may exist N >; 1 that minimizes the mean delay. We also investigate the bound on given percentile of overall delay. We observe that the delay bound is nearly linear in mean delay in the cases tested. Therefore, similar tradeoffs exist between energy consumption and the delay bound.