Mobile ad hoc networks (MANETs) have the disadvantage of decreased network reliability due to the mobility of intermediate terminals, unstable wireless links, and battery exhaustion. The reliability of networks is characterized by their level of k-connectivity. The problem optimizing a network lifetime by minimizing power consumption at a given k-connectivity is called the transmission-power assignment problem (TPAP). There are several conventional approaches to solve this problem. However, a performance evaluation of mobile networks has not yet been conducted. This paper proposes a broadcasting method based on topology control for MANETs with the aim of achieving dual objectives of reducing power consumption and ensuring an acceptable reliability level. Simulation results show that the proposed method can ensure high network reliability and reduce power consumption.