Compared with conventional Human to Human (H2H) communications, Machine to Machine (M2M) communications have to confront much more challenges. In this paper, we focus on solutions to provide longer battery lifetime. To obtain better power saving for M2M devices, this paper proposes improved mechanisms for M2M devices, radio access networks and core networks, in which the M2M devices can work well with simplified activities under optimized signaling flow. Meanwhile, the proposed approaches do not introduce negative impacts on legacy H2H terminals. This paper provides both qualitative and quantitative analysis to show advantages of the proposed comprehensive solutions.