Recent advancements in wireless communications and sensor technologies have enabled the development of low-cost sensor networks for diverse applications, such as intelligent battlefields, earthquake response systems, military objects tracking, reconnaissance surveillance, hazardous environment exploration monitoring, industry monitoring, and smart hospitals, etc. Different applications have their own characteristics and different requirements for the wireless sensor networks (WSNs). A set of performance metrics, including energy-efficiency, self-organization ability, scalability, robustness, latency, throughput, fairness, etc., are not only used to measure the performance of protocols, but also the applicability of a wireless sensor network to a certain application. Adaptability and application-awareness of a wireless sensor network directly determines the applicability of a wireless sensor network. Due to the diversity