Recent advances in wireless communications and electronics has enabled the development of low cost, low data rate wireless sensor networks (WSNs). WSNs have been an effective solution for real-time sensing and control services by the use of small number of sensors installed over small area. However, as demands for large scale applications such as disaster prediction, building/factory automation and the Smart Grid dramatically increase; conventional WSNs encounter a critical challenge to scale their network size a lot as well as ensure reliability and energy efficiency. In this work, we consider the design of operating profile for a large scale sensor network. To this end, we design some core communication techniques jointly considering Network layer, MAC layer, and PHY layer. Also, we efficiently combine each communication technique to maximize energy efficiency. The newly designed sensor network will be applied to building/factory automation and Smart Grid network.