Energy minimization by dynamic base station switching in heterogeneous cellular network

5G communication technologies are expected to provide high rate and low delay services. To meet the requirements, more base stations (BS), including macrocell BS (MacBS) and microcell BS (MicBS), have to be deployed. In this dense multi-tier heterogeneous networks, the user quality of service (QoS) can be significantly improved by shortening communication distance between base stations and users. However, the network energy consumptions of base stations have been growing quickly. How to save energy consumption in these dense layered network has become a problem we have to face. In this paper, we proposed a microcell BS (MicBS) switch algorithm to reduce the network energy consumption. The BS energy consumption is associated with traffic load, which is denoted as the number of users a BS serves. Considering the time-varying traffic load, we proposed a metric named coverage ratio to characterize how many users can enjoy the services. When the coverage ratio exceeds the upper threshold, a switch off algorithm is activated. MicBSs whose energy costs are higher than their economic profit will be switched off one by one. On the contrary, if this metric is below the lower threshold, a switch on algorithm is activated. A group of inactive MicBSs surrounded by multiple unserved users will be switched on simultaneously. After the switching operations, the network coverage ratio is expected to fall between the upper and lower bounds. Simulation results show that the coverage ratio is kept with the desired level. Compared to some existing algorithms, the proposed algorithm shows more flexible switching operation and more effective energy saving.