Wireless sensor networks (WSNs) utilize fast, cheap, and effective applications to imitate the human intelligence capability of sensing on a wider distributed scale. But acquiring data from the deployment area of a WSN is not always easy and multiple issues arise, including the limited resources of sensor devices run with one-time batteries. Additional WSN concerns include the external environment, routing, data aggregation, and ensuring quality of service (QoS) and security. Solutions have been developed for various types of application scenarios, but many problems still remain...