Abstract
A wireless sensor network (WSN) usually consists of a large number of sensor nodes deployed in a certain physical environment. The sensors are typically low-cost, low-power, and small-size and work collaboratively to collect the physical or environmental information and transmit it to the sink node for processing. WSNs have been attracting much research interest from academia and industry alike in the past decade. Still, there are many challenging issues that remain unresolved. The objective of this special issue is to provide a venue for researchers to propose new, novel algorithmic solutions to a wide range of problems in WSNs.
WSNs are data-centered networks. Therefore, data gathering and routing is one of the crucial issues for WSNs. Some papers in the special issue propose new routing techniques to improve the data delivery ratio. “PUAR: Performance and Usage Aware Routing Algorithm for Long and Linear Wireless Sensor Networks” proposes a low-energy and QoS-supported uneven clustering routing algorithm based on the labor cost. “An Energy-Efficient and Relay Hop Bounded Mobile Data Gathering Algorithm in Wireless Sensor Networks” studies the energy consumption model of the WSN with mobile data gathering, and a new novel algorithm EEBRHM is proposed to optimize the network lifetime of WSNs. In the paper “EHCM: A Multihop Aided Wireless Routing Protocol Based on Flow Priority in Smart Grid,” a new routing scheme called EHCM is presented to choose a relay node based on energy consumption and residual energy in the multihop communication mode. Moreover, there are some papers resolving routing issues in related fields such as 6LoWPAN, VANETs, and mobile social networks. For example, “Design and Optimization of Hierarchical Routing Protocol for 6LoWPAN” improves the HiLow protocol in aspects of interconnection between the Internet and 6LoWPAN and proposes a network routing path recovery approach. “Parking Backbone: Toward Efficient Overlay Routing in VANETs” presents a novel routing protocol based on a virtual overlay network formed by on-street parked vehicles for vehicular ad hoc networks. “A Service-Based Selfish Routing for Mobile Social Networks” proposes a selfish routing method based on node selfishness.
Localization is another important issue in WSNs since it plays a critical role in many applications such as target tracking. If the users cannot obtain the accurate location information, the related applications cannot be accomplished. The paper “Robust TDOA Localization Algorithm for Asynchronous Wireless Sensor Networks” presents a tag localization algorithm based on the time-difference-of-arrival (TDOA) of mobile tag signal for asynchronous WSNs with N anchors (nodes with known locations) and a large number of mobile tags. “Constrained Cross Entropy Localization Technique for Wireless Sensor Networks” introduces constrained cross entropy (CCE), enhancing the localization accuracy by penalizing the identified sensor nodes affected by the flip phenomenon in the neighborhood. “Indoor Mobile Localization in Mixed Environment with RSS Measurements” proposes an indoor mobile localization scheme with RSS measurements in a mixed LOS and NLOS environment based on an effective unscented Kalman filter- (UKF-) based Interactive Multiple Model (IMM). Also, a constrained extended Kalman filter is employed in the paper “Constrained Extended Kalman Filter for Target Tracking in Directional Sensor Networks” to track target in directional sensor networks, which effectively integrates direction and measurement information of the directional sensors.
Communication is usually the most energy-consuming operation in WSNs. Power control is the most efficient way to significantly reduce energy consumption. “Scheduling and Power Control for Energy-Optimality of Low Duty Cycled Sensor Networks” quantitatively investigates the trade-off between the duty cycle and network performance and develops a scheduling algorithm based on the well-known Lyapunov optimization framework. “Parameter Optimization of a Temperature and Relative Humidity Based Transmission Power Control Scheme for Wireless Sensor Networks” presents the refinements of a novel transmission power control (TPC) algorithm based on temperature and relative humidity.
The Medium Access Control (MAC) protocol decides which competing nodes can access the shared medium and ensures that no two nodes are interfering with each other's transmissions. In the paper “Collision Tolerance: Improving Channel Utilization with Correlatable Symbol Sequences in Wireless Networks,” an MAC protocol is proposed, which advocates simultaneous accesses from multiple senders to a shared channel, while allowing collisions instead of avoiding them. The paper “ARS: An Adaptive Retransmission Scheme for Contention-Based MAC Protocols in Underwater Acoustic Sensor Networks” introduces a novel adaptive retransmission scheme, which dynamically selects an optimal value of the maximum number of retransmissions, so that the successful delivery probability of a packet is maximized for a given network load.
In this special issue, the readers can also see papers tackling miscellaneous issues such as model analysis, data management, and applications. The paper “Probabilistic Model Checking: One Step Forward in Wireless Sensor Networks Simulation” presents the formal modeling and initial validation of a novel collision resolution algorithm for WSNs. “Distributed Data Mining Based on Deep Neural Network for Wireless Sensor Network” introduces a distributed data mining method based on deep neural network (DNN), by dividing the deep neural network into different layers and putting them into sensors. There are two papers designing new applications for WSNs. In the paper “HeadsUp: Keeping Pedestrian Phone Addicts from Dangers Using Mobile Phone Sensors,” the authors develop a walk pattern recognition system, which can issue a warning and lock the screen when one looks at the mobile phone while walking, by calculating the movement pattern of the mobile phone user based on the sampling from the embedded sensors, such as accelerometer and gyroscope. “Scheduling with Collaborative Mobile Chargers Inter-WSNs” models the mobile charge problem in 2-dimensional WSNs as a Vehicle Routing Problem with Time Windows (VRPTW) and proposes a local optimization algorithm by considering the collaborative charging among the mobile chargers. Furthermore, some authors integrate the methods of cognitive radio with WSNs. “A Distributed Q Learning Spectrum Decision Scheme for Cognitive Radio Sensor Network” analyzes the channel characteristics and the energy efficiency of networks and proposes a joint channel selection and power control spectrum decision algorithm based on distributed Q learning. In the paper “A Multiobjective Evolutionary Algorithm for Energy-Efficient Cooperative Spectrum Sensing in Cognitive Radio Sensor Network,” a fast differential evolution algorithm is introduced to optimize both the energy consumption and spectrum sensing performance at the same time, by transferring the joint optimization problem to a multiobjective optimization problem with a comprehensive performance metric.
We hope that the readers of this special issue will find topics in the papers to be of interest and wish them a rewarding experience reading it.