Enabling Technologies for Next-Generation Sensor Networks: Prospects,Issues,Solutions,and Emerging Trends

Despite significant advancements in all aspects, canonical wireless sensor networks (WSNs) are yet unable to surmount many operational challenges which strangle their widespread deployment. This is primarily due to inherent resource-constrained (e.g., limited energy, bandwidth, and storage) nature of these networks at all levels. Recently, researchers have envisaged the potentials of integrating WSNs with other prominent technologies such as multirobot networked systems, Cloud, and RFID. These integrated next-generation sensor networks (NSNs) are expected to introduce wide range of novel applications besides coping with such challenges. For example, robot-assisted WSNs not only cater for energy issues but also enable autonomous and intelligent interaction with the environment. Similarly, integration of sensor-cloud can provide powerful, scalable storage and processing infrastructure for large-scale applications. However, integration/federation of these technologies introduces new issues and challenges such as multirobot task distribution, collaboration, and coordination.

This special issue aimed at fostering high quality submissions that articulate recent advancements in NSNs, highlight open research challenges, and indicate possible future directions. This special issue solicited novel research on the design, architecture, algorithms, and protocols for existing and prospective applications of NSN. We received a number of quality submissions from different parts of the world. However, only diverse collection of 11 high quality papers authored by eminent researchers and scholars passed through a rigorous review process. We provide highlights of the accepted papers in the following.

The paper authored by P. Khan et al. analyzed the performance of MAC protocol under different access periods in wireless body area network (WBAN). To estimate performance metrics such as energy consumption, normalized throughput, and mean frame service time, they employed Markov chain to develop an analytical model under nonsaturated heterogeneous traffic scenarios. They considered different access phases specified in the IEEE 802.15.6 standard for different user priorities and access methods. Their study concludes that unnecessary deployment of exclusive access phase (EAP) in WBAN using CSMA/CA degrades the overall system throughput, consumes more energy per packet, and leads to higher delay for nonemergency nodes. To address variety of scheduling problems and reduce complexity, S. T. Bakhsh et al. proposed two distributed MAC protocols for NSNs. The proposed protocols can effectively adapt dynamic topology changes and do not require any synchronization mechanism. The performance supremacy of the proposed protocols over DRAND has been demonstrated through simulation results.

To detect anomalies in WSNs, R. Rizwan et al. proposed a bioinspired mechanism using Negative Selection Algorithm (NSA). The proposed NSA employs a detector set containing anomalous packets to identify certain anomalies. Simulations experiments are conducted on a large dataset and high accuracy in detecting anomalies is reported. The paper authored by I. Ahmad proposed a feature selection method based on particle swarm optimization (PSO) for intrusion detection in WSN. The proposed method picks optimal subset of features from the principal space. The performance of the proposed method is validated and compared to GA-based and PCA-based schemes using standard KDD dataset. To investigate the security of SCADA system, A. Shahzad et al. conducted a study to examine the security of DNP3 protocol. They developed a simulation environment employing intelligent connected sensors deployed for water pumping process and security is analyzed inside DNP3 protocol stack. The paper authored by M. Abazeed et al. reviewed the challenges of secure routing in current and next-generation wireless multimedia sensor networks (WMSN). This study comprehensively reviewed critically state-of-the-art routing and security approaches for WMSN along with their features and limitation.

Two distributed mobility management schemes for 6LoWPAN networks are proposed in the paper authored by M. Gohar et al. The proposed schemes implemented home agent, local mobility anchor, and mobile access gateway functions and the handover operations are performed directly between two neighboring 6LoWPAN gateways. The performance of the proposed schemes is shown to outperform contemporary approaches in terms of registration and handover delays. To improve network lifetime and stability, Hybrid Energy Efficient Reactive (HEER) and Multihop HEER (MHEER) protocols are proposed by M. Akbar et al. MHEER designates cluster heads based on maximum energy and variants of both protocols with sink mobility are also proposed. The performance of the proposed schemes is shown to outperform contemporary schemes.

The paper authored by T. R. Sheltami et al. evaluated the performance of two state-of-the-art time synchronization protocols (i.e., Flooding and Recursive Time Synchronization Protocol). For time synchronization in WSN, the former uses broadcast, while peer-to-peer mechanism is used by the latter. Using different topologies, the performance of the two protocols is analyzed based on three metrics, that is, synchronization message count per cycle, bandwidth, and convergence time.

A. Stefanov investigated the distortion performance of multihop underwater acoustic sensor networks (UASN) in his paper. This study evaluates distortion when the sensor-to-sensor links experience Rician fading and there is interference from other sensors in the network. The results of the numerical analysis illustrate the coverage-limited and the interference-limited region. The impact of retransmissions on the distortion performance is also considered.

The paper authored by R. M. Mehmood and H. J. Lee provided a time and frequency domain analysis on EEG data through Brain Sensors Network. They computed the signal regularity to view the emotional conditions (i.e., neutral, sad, happy, calm, and scared). Their study concludes that delta frequency wave has more energy in most cases and it can be used for emotion recognition in real-time EEG systems.