Static Nodes Research Articles

Efficient Green Protocols for Sustainable Wireless Sensor Networks

Nowadays, wireless sensor networks (WSNs) are widely adopted by many civil/military applications. However, due to the limited capacity of the built-in battery, the lifetime of the sensor is limited, which in turn affects the working time of the whole system. Therefore, the limited energy supply is the most direct and critical constraint to maintain the long-term and efficient operation of the system. Accordingly, reducing energy consumption/improving energy efficiency is an essential prerequisite for designing a sustainable WSN. To address this problem, many approaches have been proposed. To help readers fully understand the techniques/methods in this area of research, we present a taxonomy of the existing energy-efficient strategies for achieving sustainable WSNs. We first introduce some basic concepts and assumptions commonly adopted in energy-efficient WSNs designs. Then, we discuss existing approaches designed for conventional WSNs (consisting of static nodes or nodes with limited mobility) from five aspects: clustering-based schemes, node deployment strategies, node scheduling algorithms, energy-efficient routing schemes, and energy-efficient joint designs. We compare these schemes and highlight their strengths and drawbacks. Additionally, we discuss state-of-the-art approaches relying on some emerging techniques, e.g., high-mobility data collectors, energy-harvesting techniques, etc. Finally, we conclude the paper and present some open challenges.

Wireless energy consumption optimisation using node coverage controlling in linear-type network

With the mushrooming development of automatic, intelligent and unmanned technologies, the application of wireless sensor network has become a hot topic. There is a kind of narrow-band structure, such as corridor or tunnel, which needs to use wireless sensor network for parameter sensing. To address unbalanced energy consumption of wireless nodes along length direction, this paper proposes a coverage controlling strategy, and linear-type network is built using several wireless nodes. A base station node is equipped in narrow band structures. Firstly, the wireless perception models are analysed aiming at special monitoring environments, which contain routing path, coverage model, link load and data credible rate; secondly, the survival lifetime of linear-type network is solved based on energy consumption of every wireless node; thirdly, considering the accidental death of deployed nodes, time-sharing scheduling strategy is designed to guarantee the stability of monitoring linear-type network; finally, the experimental results show that the proposed coverage control strategy can optimise the survival lifetime and the energy efficiency of linear-type network, which can provide the reference for node coverage in linear structures.

Wireless energy consumption optimisation using node coverage controlling in linear-type network

With the mushrooming development of automatic, intelligent and unmanned technologies, the application of wireless sensor network has become a hot topic. There is a kind of narrow-band structure, such as corridor or tunnel, which needs to use wireless sensor network for parameter sensing. To address unbalanced energy consumption of wireless nodes along length direction, this paper proposes a coverage controlling strategy, and linear-type network is built using several wireless nodes. A base station node is equipped in narrow band structures. Firstly, the wireless perception models are analysed aiming at special monitoring environments, which contain routing path, coverage model, link load and data credible rate; secondly, the survival lifetime of linear-type network is solved based on energy consumption of every wireless node; thirdly, considering the accidental death of deployed nodes, time-sharing scheduling strategy is designed to guarantee the stability of monitoring linear-type network; finally, the experimental results show that the proposed coverage control strategy can optimise the survival lifetime and the energy efficiency of linear-type network, which can provide the reference for node coverage in linear structures.

EH-MAC: Extensive Hybrid Medium Access Control Mechanism for Improving Network Lifetime and Communication Efficiency

The domain of image signal processing, image compression is At Contribution of hybrid protocol has been gaining importance owing to more demands of energy efficiency among the communicating nodes in Wireless Sensor Network (WSN). Review of existing literatures shows that hybrid MAC protocols has been not been evaluated over heterogeneous environment in WSN with no much consideration of temporal factors connected to it. Hence, the proposed system introduces a novel extensive hybrid MAC protocol (EH-MAC). The system introduces a mechanism where time synchronization with respect to assigned dynamic slots are considered followed by inter-synchronization of network. Apart from this, a relay node selection process has been used uniquely considering the state of static and mobile sensor nodes in the analysis environment. The proposed system also introduces an unique selection of node unlike conventional MAC protocols which offers a capability to control any form of idle listening within WSN. The simulated outcome of the proposed system has been found to offer higher residual energy, faster response time, lower memory consumption, and optimal throughput delivery performance in comparison to standard existing hybrid MAC schemes in WSN.

An Extremely Accurate Time Synchronization Mechanism in Fog-Based Vehicular Ad-Hoc Network

Fog-based Vehicular ad-hoc networks (VANETs) are new kinds of network that combine fog computing and mobile ad-hoc networks appeared in recent years, which can be used in monitoring traffic, smart driving, safe driving, and so on. Fog-based VANET is composed of a large number of dynamic nodes and static nodes, which is a heterogeneous network. Due to the heterogeneity of fog-based VANET, there is a large difference in clock rate between different nodes. It makes clock of nodes soon become inconsistent. The inaccurate clocks would lead to problems such as imprecise duty-cycle scheduling and wrong events sequence, etc. Synchronizing the clocks needs multiple message exchanges among the nodes. However, due to the mobility of the fog-based VANET, the network topology changes dynamically, which may cause synchronization packets to fail to be transmitted to a node that needs to be synchronized. In this paper, a precise time synchronization mechanism for fog-based VANET is proposed. The mechanism uses two-way message exchange method to estimate clock offset through analyzing the mobility of dynamic nodes. Clock skew is corrected using a carrier frequency offset (CFO) based hardware clock frequency estimation and considering the Doppler effect. Theoretical analyses and simulation results show that our time synchronization mechanism achieves highly accurate time synchronization.

Software defined network based self-diagnosing faulty node detection scheme for surveillance applications

Unmanned aerial vehicles (UAV) can be used as basic elements of the sensor network or an upgrade of existing network that are built with static wireless sensor nodes. Wireless Networks (WN) are utilized across in surveillance in all domains, like natural disasters, agriculture, water, forest, military, buildings, health monitoring, disaster relief & emergency management, area and industrial surveillance, due to its wider applicability. Though the performance of WN is satisfactory, it still suffers from several challenges such as energy efficiency, reliability and security. This work attempts to render reliability to the wireless network as sensor physical node in network by detecting the faulty sensor nodes. The faulty sensor nodes degrade the performance of the complete sensor network and hence, it is necessary to detect the faulty sensor nodes to attain better Quality of Service (QoS) with software defined in network. The proposed method detects the faulty sensor nodes using software defined network approach by means of Reward-and-Punishment Model (RPM) and the hypothetical analysis of Dempster–Shafer (DS) theory protocol approach. The performance of the proposed approach is observed to be satisfactory in terms of Quality of Service parameters of faulty node detection accuracy, energy consumption and network lifetime.

FAREY SEQUENCES MAP PLAYABLE NODES ON A STRING

AbstractNatural harmonics, i.e. partials and their harmonic series, may be isolated on a vibrating string by lightly touching specific points along its length. In addition to the two endpoints, stationary nodes for a given partial n present themselves at n − 1 locations along the string, dividing it into n parts of equal length. It is not the case, however, that touching any one of these nodes will necessarily isolate the nth partial and its integer multiples. The subset of nodes that will activate the nth partial (termed playable nodes by the authors) may be derived by following a mathematically predictable pattern described by so-called Farey sequences. The authors derive properties of these sequences and connect them to physical phenomena. This article describes various musical applications: locating single natural harmonics, forming melodies of neighbouring harmonics, sounding multiphonic aggregates, as well as predicting the relative tuneability of just intervals.

Fault-resilient and QoS centric dynamic network sensitive routing protocol for mobile-WSNs

The exponential rise in the demand of wireless communication has revitalized academia-industry to achieve more efficient networking solution. To meet these demands wireless sensor networks (WSNs) have always been the dominating solution, however static node and network characteristics confine its suitability for applications under dynamic topology. Strengthening WSN with fault-resilient route decision by exploiting dynamic network parameters such as current congestion probability, buffer availability, and packet injection rate can ensure reliable and quality of service (QoS) communication over WSNs under dynamic network topology. With this motivation, in this paper multiple network parameter-based fault-resilient and QoS centric dynamic network sensitive routing protocol (FQ-DNSRP) is developed. FQ-DNSRP exploits network parameters at the different layers of the IEEE 802.15.4 protocol stack to derive a node rank matrix that helps in identifying best forwarding node for deadline sensitive and reliable data transmission. Simulation results revealed that the proposed FQ-DNSRP model exhibits satisfactory performance for real time data delivery over mobile-WSNs that can be significant for numerous applications, including IoT ecosystems.

LNR-PP: Leaf Node Count and RSSI Based Parent Prediction Scheme to Support QoS in Presence of Mobility in 6LoWPAN

6LoWPAN network consists of embedded devices and sensors that senses environmental data and passes it to a root called as a 6LBR (6LoWPAN Border Router) which further transfers it to an Internet server for aggregation and processing. Earlier definition of 6LoWPAN consists of devices which are static with constrained resources such as computing power, memory, battery power and communication bandwidth. Recent additions such as mobile devices which are part of the 6LoWPAN network often cause frequent topology changes and disconnections, leading to degraded performance of the network. Handover delay, data loss rate, number of control messages, energy utilization are some of the performance metrics that has been focused and improved by recent works in the literature. But the proposed approaches work well when the number of mobile nodes and mobility rate are moderate. We identify the issues that arise in the 6LoWPAN RPL based network due to higher number of mobile nodes and higher mobility rate which causes problems like delay in data transmission and degraded parent node performance. In this paper we study, analyse and propose modifications in the popular protocols that support mobility in 6LoWPAN such as EC-MRPL. We propose a best-effort scheme called LNR-PP (Leaf node count and RSSI based Parent Prediction) to identify affected Static Nodes (SN) to whom large number of Mobile Nodes (MN) are connected. We call this scheme as a best effort since the parent prediction depends upon the number of neighbours available within the reach of MN in mobility. LNR-PP performs balanced leaf node (Mobile Node) allocation to SN in an effort to minimize the number of RPL control message packets, delay in forwarding data from the MN and power required to transmit control and data packets through SN. This enables the mobile nodes (MN) to communicate with DODAG-ROOT with guaranteed QoS measures under high mobility scenario. We developed a mathematical model to realize the benefits of the proposed scheme which can be incorporated into EC-MRPL and simulated with sample network parameters in MATLAB. The results obtained through simulation shows a significant improvement in term of number of RPL control message packets such as DIS and DIO, power requirement to transfer control and data packets through SN and delay encountered by SN while forwarding large volume of data from MN.

Fault resilient routing based on moth flame optimization scheme for underwater wireless sensor networks

Fault resilient routing is a typical issue for underwater wireless sensor networks ($$ UWSNs $$) due to contact of underwater creatures, mobility of nodes and natural disaster. In the existing studies, most of the researchers introduced routing scheme for routing the packets towards the base station through a cluster head. However, these schemes use static or mobile nodes for deployment, but nodes move from its original position to another position and get stuck in a particular region due to ocean current, natural disaster and environmental interference. Therefore, this leads to high energy depletion, link failure, disjoint path and overloaded data. To resolve this issue, we have proposed fault resilient routing based on moth flame optimization ($$ MFO $$) scheme for transferring the packets towards the base station through autonomous underwater vehicles ($$ AUVs $$). In this scheme, $$ AUVs $$ is used instead of cluster head to avoid the reclustering, overloading problem and it also feasible for large scale networks. There may be a disjoint path issue, so we have deployed additional mobile nodes with the help of $$ AUVs $$ within the network. Further, a novel fitness function is integrated with the $$ MFO $$ scheme to overcome the link failure problem. The proposed scheme is applied to select the best forwarding node for transmitting the packets towards the nearest $$ AUVs $$ using multi-hop acoustic links. In $$ UWSNs $$, $$ AUVs $$ is placed to move the packets towards the $$ BS $$ from lower level to upper level. Performance evaluation of proposed scheme shows better result in terms of fault resilient, residual energy, network lifetime, packet delivery ratio and convergence rate than the existing scheme under the different network scenario.

Hierarchical Cooperation Improves Delay in Cognitive Radio Networks with Heterogeneous Mobile Secondary Nodes

This paper characterizes the throughput and delay performance of Cognitive Radio Networks (CRNs), where both primary and secondary networks coexist in a unit torus. Specifically, the primary network consists of static primary nodes (PNs) of density $n$ n , which have a higher priority to access the spectrum. In contrast, the secondary network consists of mobile secondary nodes (SNs) of density $m=n^{\beta }$ m = n β with $\beta \geq 1$ β ≥ 1 , which move according to a hybrid random walk mobility model and have opportunistic access to the spectrum without affecting primary packet transmissions. Motivated by the fact that cooperation between primary and secondary nodes leads to possible improvement on the performance of CRNs, as well as the fact that the heterogeneous moving regions of secondary nodes will bring about further improvement, we propose a novel hierarchical cooperative scheduling mechanism, where secondary nodes serve as relays for primary packet transmissions by exploiting their mobility heterogeneity and geographic information. Our findings include: (i) For the primary network, stronger mobility heterogeneity of secondary nodes leads to better delay performance of the primary network, and meanwhile the delay scaling can be significantly reduced to $\Theta (n^{\sqrt{\beta /{(4\;\log n)}}}\log ^{3/2}n)$ Θ ( n β / ( 4 log n ) log 3 / 2 n ) when a near-optimal per-node throughput of $\Theta ({1}/{\log n})$ Θ ( 1 / log n ) is obtained. (ii) For the secondary network, we also adopt a similar hierarchical cooperative scheduling mechanism, and obtain a near-optimal per-node throughput of $\Theta {(1/{\log m})}$ Θ ( 1 / log m ) with the delay scaling of $\Theta ({m^{1-(1/\sqrt{\log m})}})$ Θ ( m 1 - ( 1 / log m ) ) . (iii) The delay of secondary source-destination pairs is determined by the moving region of destinations and has no relation with sources. Our work provides deeper understandings of the cooperation, heterogeneous mobility, and geographic information on the performance of CRNs, and sheds light on designing more efficient CRNs.

Non-dominated Sorting Genetic Algorithm-II for Throwbox Deployment in Delay Tolerant Networks

Delay-tolerant networks (DTNs) are basically opportunistic networks and uses store-carry-and-forward switching for message forwarding. Performance of DTNs can be improved by placing stationary nodes, called throwboxes which increases the contact opportunities among nodes. Throwbox is viewed as relaying node and the message delivery is enhanced by spreading as many messages as possible. Increasing the contact opportunities in throwbox based DTN model depends on the deployment of throwboxes in suitable places. The objective of this paper is to identify optimal deployment locations of the throwboxes with a pre-specified transmission range, and to maximize the coverage of all the throwboxes in order to increase average delivery and to reduce the average delay among all the nodes in the network. We use Non-Dominated Sorting Genetic Algorithm–II for optimizing the deployment of throwboxes in DTN. The simulation results are analyzed for better strategy in deploying throwboxes and to improve the performance of throwbox-augmented DTNs.

An intelligent multi-floor indoor positioning system for cloud-based environment

Optimal node positioning to ensure energy efficiency is a challenge in Wireless Sensor Networks (WSNs). Energy can be conserved in WSN when the sensors are positioned at optimum locations. In this paper, an intelligent scheme to form multi-floor clusters by subdividing the topology into regions is proposed. Some random nodes are elected as Cluster Heads (CHs). The CH determines the number of neighboring nodes in each floor of the indoor surrounding. It sends requests to the members in the cluster to measure the Received Signal Strength (RSS). The node positions are estimated by applying Extreme Learning Machine (ELM) on the recorded RSS fingerprints. Kernelized ELM provides access to high dimensional input space with less computational cost and time. The proposed scheme provides more efficient control over the network during fluctuations. Once clusters are set up, the RSS of each node is collected to create a fingerprint database. The target node position is determined by matching the currently recorded RSS with the stored fingerprint. The performance of the proposed intelligent clustering technique is analyzed for both static and mobile nodes with varying samples and reference points. Extensive experiments conducted show that the propounded scheme offers better scalability and reduced Cumulative Percentile of Error (CPE).

Multi-model based pressure optimization for large-scale water distribution networks

In the operation of urban water distribution networks (WDNs), the supply pressure to users should be kept low while meeting the lower bound to satisfy users’ water demand, reduce leakages and power consumption. In this paper, a multi-model based pressure optimization method for large-scale WDNs is proposed, where the pressure of the whole WDNs is represented by the pressure of key nodes and key pump station nodes based on the calculation of pressure transfer relationship and a developed network simplification method, the multiple linear models are constructed to approximate the pressure transfer relationships, and the models between the selected key nodes and key pump station nodes are used for the pressure optimization of the whole WDNs. The proposed methods are operation data based, which overcomes the difficulty in constructing accurate and complicated hydraulic models for large-scale WDNs. The network simplification reduces data requirements in multiple model construction and ensures real-time control. In the simulation case, which is part of Shanghai’s WDNs, the supply pressure to users is optimized to lower and more homogeneous value without violating the lower bound by applying the proposed approach, which is significant in reducing water leakages and energy consumption.

Polynomial and matrix based key management security scheme in wireless sensor networks

Wireless sensor networks (WSN) due to its constrained resources and wide application in different fields like in military area and battlefield has brought the focus on the implementation of security in network. In this paper a key management scheme is suggested for heterogeneous and hierarchical WSN to provide improved secure key distribution and authentication between base station, cluster head and sensor node while maintaining less complexity. The scheme uses the multivariate symmetric polynomial and matrices for the generation of keys in WSN and is called Hybrid Key Management Security scheme (HKMSS). In this scheme between base station and head, multivariate symmetric polynomial is used while between head to cluster node symmetric matrix is used for key generation which reduces the overhead at the node as it is resource constrained. The matrix mechanism for establishing secret key between head and nodes ensure secure communication between head and node. The proposed scheme has reduced computational and storage overhead with improved security, network lifetime and network connectivity.

Investigating the Performance of Point to Multipoint Microwave Connectivity across Undulating Landscape during Rainfall

One of the most debated issues surrounding wireless connectivity is performance especially under different topographic and climatic scenarios. Performance has a direct relationship with throughput measured in terms of how well a given wireless connectivity provides consistent services over a given period compared to the wired alternative. Research has shown that wireless connectivity is constrained by significant physical components such as topography, weather conditions, propagation frequency, and distance. It is commonplace to see notable vendors of wireless network products make claims as to how their technologies are designed to remedy any signal degradation that may arise from the aforementioned physical elements. This paper is aimed at evaluating the performance of a point to multipoint connectivity using Ubiquiti’s 5.8 GHz Point to Multipoint Base Stations deployed within a landscape marked by series of undulating highlands and lowlands. In this experiment, a base station node is established with connectivity to two other nodes of same specifications with one node as the destination radio whereas the other acts as the control which is located on a table land. The nodes were separated by triangular distances of 3 km and network connectivity was maintained over thirty days during periods of rainfall. Packets sent and received across each node was carefully recorded. The results from the analysis showed that packet losses to and from the control node was significantly lower than that of the other node under same weather conditions.

A DDoS attacks traceback scheme for SDN-based smart city

Smart City (SC) has brought tremendous opportunities and exciting challenges. Network security is one of the most important challenges in SC networks. Software-Defined Networking (SDN) is more likely to be the target of Distributed Denial of Service (DDoS) attacks due to the risk of a single point of failure. To better defend against DDoS attacks, we focus on tracing the source and propose a statistics-based traceback scheme using the advantages of the SDN architecture. We analyze the changes of flow through the Base Station (BS) nodes to calculate the eigenvalue and establish the anomaly tree. Then prune it with DDoS detection algorithm to get the attack path. Through the experiments, we obtain the optimal parameters to make the proposed scheme more flexible and effective. It shows that the scheme consumes fewer network resources and saves time than traditional ones while keeping the DDoS defense accuracy at a high level.

Strategy of Repairing Coverage Hole for Different Holes Shapes in Heterogeneous Wireless Sensor Networks

For the randomness of the initial deployment of sensor nodes and the exhaustion of node energy during network operation, the problem of covering holes may be generated, the coverage repair strategies for different holes shapes are proposed. Firstly, the holes polygons formed by static nodes of randomly deployed heterogeneous wireless sensor networks are classified. Secondly, according to different polygon types, different repair strategies are adopted to determine the location of virtual repair nodes. Finally, according to the distance between the virtual repair node and the mobile node, the relation function of energy threshold value, and the movement of the mobile node with finite distance, the covering cavity is repaired. Simulation results show that the coverage is improved by adopting different repair strategies according to different holes types.

Hybrid area exploration–based mobility‐assisted localization with sectored antenna in wireless sensor networks

SummaryIn common practice, sensor nodes are randomly deployed in wireless sensor network (WSN); hence, location information of sensor node is crucial in WSN applications. Localization of sensor nodes performed using a fast area exploration mechanism facilitates precise location‐based sensing and communication. In the proposed localization scheme, the mobile anchor (MA) nodes integrated with localization and directional antenna modules are employed to assist in localizing the static nodes. The use of directional antennas evades trilateration or multilateration techniques for localizing static nodes thereby resulting in lower communication and computational overhead. To facilitate faster area coverage, in this paper, we propose a hybrid of max‐gain and cost‐utility–based frontier (HMF) area exploration method for MA node's mobility. The simulations for the proposed HMF area exploration–based localization scheme are carried out in the Cooja simulator. The paper also proposes additional enhancements to the Cooja simulator to provide directional and sectored antenna support. This additional support allows the user with the flexibility to feed radiation pattern of any antenna obtained either from simulated data of the antenna design simulator, ie, high frequency structure simulator (HFSS) or measured data of the vector network analyzer (VNA). The simulation results show that the proposed localization scheme exhibits minimal delay, energy consumption, and communication overhead compared with other area exploration–based localization schemes. The proof of concept for the proposed localization scheme is implemented using Berkeley motes and customized MA nodes mounted with indigenously designed radio frequency (RF) switch feed network and sectored antenna.

Mobility Aware Duty Cycling Algorithm (MADCAL) A Dynamic Communication Threshold for Mobile Sink in Wireless Sensor Network.

The hotspot issue in wireless sensor networks, with nodes nearest the sink node losing energy fastest and degrading network lifetime, is a well-referenced problem. Mobile sink nodes have been proposed as a solution to this. They do not completely remove the hotspot problem though, with nodes the sink passes most closely still expending more energy than others. This study proposes a lightweight algorithm, located in the media access control (MAC) layer of static nodes and utilising knowledge of predictable sink node mobility. This is in order to create a dynamic communication threshold between static nodes and the sink, within which static nodes awaken, lessening competition for sink communication between nodes. In utilising predictable mobility and factors already known to the static node, such as location and interference range, there is no need for energy-consuming messaging. Analysis and simulation results, tested on a lightweight implementation of a carrier-sense multiple-access-based MAC protocol, show a significant improvement in energy consumption in both controlled and random environments, with frame delivery improved to the point where sink speed is negated. This is when compared to the existing duty cycling approach.