Wireless Sensor Networks (WSNs) have opened up many new possibilities for emerging applications in the area of event tracking and surveillance. However, when compared to the great research interest in this topic, only a limited number of frameworks have been deployed in the real world due to multi-hop and long hop delivery over many constraints on both nodes and networks. Currently, mobile sink nodes can be a feasible solution for data collection in an energy efficient way in order to reduce the total energy consumption to a small number of hops. Unlike static sink approaches, the mobile sink approach requires a new paradigm in order to collect data such that sensed data is correctly delivered to mobile nodes. In this situation, a packet may be delivered to a previous location or a node needed to keep a packet until a mobile sink moves to a nearby place. In addition to these cases, the movement of mobile sink nodes may lead to many research challenges caused by their frequent path changes.

Despite these challenges, there is a large amount of research introducing mobile robots or unmanned aerial vehicles as mobile sinks recently. With the help of these systems, many research challenges can be simplified - however the energy efficiency problem with respect to their communications remains as yet unsolved. Hence, there is a tremendous need for researchers and engineers to have a comprehensive knowledge of the latest advances in mobile sink technology.

The aim of this Special Issue is to present both review articles focusing on the state-of-the-art of the open technical problems and challenges in communication and networking for mobile sink in WSN, and original research articles that tackle the problem of efficient integration of novel solutions with existing mobile sink technology. Articles that focus on the performance evaluation and comparison with existing standards are especially welcome.

Potential topics include but are not limited to the following:

• Data collection protocols for mobile sink
• Mobility models of mobile sink
• Energy efficient and delay tolerant communication for mobile sink
• Traffic models for mobile sink
• Software/hardware platforms for mobile sink
• Protocol simulations, testbeds, and demonstrators for mobile sink
• Network deployment and localization for mobile sink
• Network architecture for mobile sink technology
• Strategies for the applications multiple mobile sinks
• Trajectory Design for mobile sink
• Overlaying and cross layer design aspects of mobile sink
• Practical applications with mobile sink