Recently, a number of applications in military and environmental monitoring have made wireless sensor networks (WSNs) a research center. Data collection from mobile sinks is more popular due to many advantages, including increased network life, energy efficiency and minimizing isolated nodes. Mobile sinks have proven to be extremely useful in wireless sensor networks, especially in large networks. With a mobile sink, visiting each sensor node is complex and may result in data loss or delay. Several recent approaches have shown that data acquisition, routing and sink mobility in a controlled path can increase WSN energy efficiency. A review of some mobile sink (MS) techniques is presented in this paper that have been researched during the past six years, followed by an analysis based on factors such as methods used, research outcomes and limitations. Finally, this survey concludes with a summary and research challenges for the future.

Wireless Sensor Networks (WSN), Mobile sink (MS), Sensor Nodes (SN), Multiple mobile sinks (MMS), Rendezvous Points.