SummaryIn this paper, a sleeping mode control for low power wireless node, that is, pico base station (PBS) in heterogeneous networks, is proposed to save energy cost with adaptation to the time‐varying traffic load. By formulating the sleep mode control problem into the framework of a standard 0/1 knapsack problem, then a dynamic programming scheme for solving the sleeping on/off mode for PBS in heterogeneous networks was investigated. The complexity of the proposed scheme is only in linear order instead of exponential complexity with conventional scheme. Furthermore, the proposed algorithm is verified in dynamic traffic environment, which consists of two kinds of hot‐spot area covered by PBSs. The simulation results show that the proposed scheme can effectively save the system energy consumption during the period of low traffic load. Copyright © 2015 John Wiley & Sons, Ltd.