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Ashikur Rahman, Salsabil Arabi, Raqeebir Rab
Wireless Sensor Network, Volume 13, pp 1-16; doi:10.4236/wsn.2021.131001

Growing client population, ever-increasing service demand, and complexity of services are the driving factors for the mobile operators for a paradigm shift in their core technology and radio access networks. 5G mobile network is the result of this paradigm shift and currently under deployment in many developed countries such as United States, United Kingdom, South Korea, Japan, and China—to name a few. However, most of the Least Developed Countries (LDCs) have very recently been implemented 4G mobile networks for which the overall role out phase is still not complete. In this paper, we investigate how feasible it is for LDCs to emphasize on a possible deployment of 5G networks at the moment. At first, we take a holistic approach to show the major technical challenges LDCs are likely to face while deploying the 5G mobile networks. Then we argue that various security aspects of 5G networks are an ongoing issue and LDCs are not technologically competent to handle many security glitches of 5G networks. At the same time, we show that most of the use cases of 5G networks are not applicable in the context of many LDCs (at least at the present time). Finally, this paper concludes that the start of the 5G network deployment in LDCs would take much longer time than expected.
Asghar Khan Muhammad, Hussain Sadam, Muhammad Asghar Khan, Sadam Hussain
Wireless Sensor Network, Volume 12, pp 37-47; doi:10.4236/wsn.2020.123003

A wireless sensor network consists of hundreds or thousands of small nodes which could either have a static or dynamic position. These nodes are deployed through normal or random distribution to report events of a particular area to the base station through sink nodes. Having limited onboard energy of sensor nodes, conservation of energy in wireless sensor network is necessary. For this purpose, a new algorithm is proposed titled Energy-Efficient-Direction-Based-Topology-Control-Algorithm (EEDBTC). In proposed algorithm, direction is the main concern whenever an event occurs the node will send data in the direction of base station so that less energy is consumed. The results of the same were compared with customary dense wireless sensor network, color based WSNs and it was observed that this algorithm is much better than previous topology control algorithms used.
Michael Bolt, J. Craig Prather, Tyler Horton, Mark Adams
Wireless Sensor Network, Volume 12, pp 1-11; doi:10.4236/wsn.2020.121001

A low-cost airborne sensor mote has been designed for deployment en masse to characterize atmospheric conditions. The designed environmental sensing mote, or eMote, was inspired by the natural shape of auto-rotating maple seeds to fall slowly and gather data along its descent. The eMotes measure and transmit temperature, air pressure, relative humidity, and wind speed estimates alongside GPS coordinates and timestamps. Up to 2080 eMotes can be deployed simultaneously with a 1 Hz sampling rate, but the system capacity increases by 2600 eMotes for every second added between samples. All measured and reported data falls within accuracy requirements for reporting with both the World Meteorological Organization (WMO) and the National Oceanic and Atmospheric Administration (NOAA). This paper presents the design and validation of the eMote system alongside discussions on the implementation of a large-scale, low-cost sensor network. The eMote represents unprecedented in-situ atmospheric measurement capabilities with the ability to deploy more than 260 times the number of sensing units as the most comparable commercially available dropsonde.
Vu Van Khoa, Shigeru Takayama
Wireless Sensor Network, Volume 12, pp 13-36; doi:10.4236/wsn.2020.122002

Wireless sensor network has been used as a landslide monitoring tool for more than one decade. The robustness of the network is important as the systems need to survive in harsh conditions. In this paper, we consider the living time of the sensor network under the influences of the small-scale landslide. We investigate the performance of famous energy-efficient routing protocol PEGASIS in both landslide case and non-landslide case. Genetic Algorithm is also applied to enhance the effectiveness of PEGASIS. The simulation results in this paper showed that the Genetic Algorithm helps to delay the first node death if it is used at the beginning of data transmission while being used every round helps to prolong last node death slightly. The impact of the Genetic Algorithm on energy usage and route length is also examined. Under the effect of landslide, with only 70% of energy are spent, the simulated protocols reduced around 30% equivalent route length while managed to keep the living time up the network up to 90.76%, comparing to cases with no landslide.
Yuya Nishimaki, Hisato Iwai, Kenya Sato
Wireless Sensor Network, Volume 11, pp 81-94; doi:10.4236/wsn.2019.116006

Adeniran Ademuwagun
Wireless Sensor Network, Volume 11, pp 13-33; doi:10.4236/wsn.2019.112002

The computational capabilities of off-the-shelf wireless sensors networks presents a limitation when more complex forms of localization algorithms are employed for location estimation purposes, particularly in an indoor environment. Range-free algorithms rely on Received Signal Strength (RSS) from sensors that are location aware (anchor nodes) as the major means of distance estimation. This paper presents a non-site specific algorithm for better estimating RSS relationship with distance. By employing a unique form of rationalization of raw RSS with respect to distance using the proposed algorithm, it is possible to enhance the reliability of RSS when employed in indoor Localization Algorithms. Consequently, this paper presents an innovative RSS-Distance rationalization algorithm for localization of objects in an indoor environment. The paper compared the proposed algorithm with Simple Moving Average (SMA) algorithm due to the wide applicability and ease of manipulation of SMA. The analysis of the proposed algorithm and SMA shows that the proposed algorithm better modifies RSS for more accurate position estimation in an indoor environment.
Yoann Charlon, Antoine Piau, Damien Brulin, Eric Campo
Wireless Sensor Network, Volume 11, pp 67-80; doi:10.4236/wsn.2019.115005

The main objective of this work is to develop a technological solution to support active aging of frail older individuals. In this perspective, we designed a connected insole in order to encourage frail elderly persons to become more active in their daily life. The project presented in this paper, funded by the French National Research Agency, aims to design and evaluate an original solution to follow and encourage walking activity. The evaluation is performed in two stages: adjusting tests in a living-lab with nine healthy elderly, then clinical evaluation of three frail patients followed over one month. We designed a noninvasive wireless insole, which automatically measures gait parameters and transmits information to a remote terminal via a secure Internet connection. The first laboratory tests of this technological solution showed good reliability measurements as well as good user acceptability. The average distance error obtained on volunteers is 3.2% and the accuracy of the average walking speed is 96.8% thanks to design of a calibration system based on a personalized stride length measurement. Finally, the introduction of an induction charging instead of a button cell makes the system perfectly autonomous. In this paper, we present the specifications of the solution, the design of the connected insole, the methods used to measure desired parameters, the results of the living-lab tests, and the work in progress.
Haythem AlHumud, Mohammed Zohdy, Debatosh Debnath, Richard Olawoyin, Sayed Ali Arefifar
Wireless Sensor Network, Volume 11, pp 1-11; doi:10.4236/wsn.2019.111001

Piyush Charan, Tahsin Usmani, Rajeev Paulus, Syed Hasan Saeed
Wireless Sensor Network, Volume 11, pp 35-45; doi:10.4236/wsn.2019.113003

Considering Wireless Sensor Networks (WSNs) in today’s scenario, sending and receiving uninterrupted sensory data remains a challenge to achieve with minimal latency and energy consumption as low as possible. Energy consumption is exponentially growing in computing devices such as computers, embedded systems, portable devices, and wireless sensor networks. Extensive research has been in practice recently to minimize energy consumption without compromising the Quality of Service (QoS) that is to provide data to the requester node with minimum Delay and high Reliability. In this paper, a cooperative caching algorithm is used with the proposed Distributed Energy Aware Routing (DEAR) protocol that attempts to minimize energy consumption by reducing the packet overhead in the network and also providing the data to the requester with minimum delay by retrieving requested datum from the nearby caching node available in the vicinity of the requester or sink node. The simulation results clearly show that the energy consumption is less when the grid-based analytical model is used against the star/cluster based model while keeping the same necessary attributes.
Tarek Srour, Ayman Haggag, Mohsen A. M. El-Bendary, Mostafa Eltokhy, Atef E. AbouElazm
Wireless Sensor Network, Volume 11, pp 47-66; doi:10.4236/wsn.2019.114004

Research works of Wireless Sensor Networks (WSNs) applications and its constraints solutions occupy wide area around the world and attract many researchers. In this paper, an important one of environmental WSN applications is presented that is the water monitoring applications. An efficient approach for monitoring and controlling water parameters in real-time is implemented utilizing merging between WSN and designed simple workstation. For implementation simplicity, two water parameters (pH and temperature) are monitored and controlled in the proposed approach. Most of past work of water monitoring presented different proposed monitoring scenarios for different water parameters only. This research work utilizes the concept of interactive WSN nodes. The interactive nodes interact with the monitored water parameters to control its value. In the base station, the collected data is analyzed and the real-time value of the monitored parameters appears on the designed Graphic User Interface (GUI). The GUI is designed using the Matlab program. Through the GUI, the operator can switch the control between automatic and manual. ZigBee module is used for implementing the wireless communications between the nodes and the workstation. Due to the cost and simplicity, two sensors only are used in the proposed approach. Different real-time experiments are performed to test and measure the effectiveness and performance of the presented approach. These experiments reveal that the presented approach is effective for water treatment and efficient more than the past proposed water monitoring scenarios.
Thoraya Al- Subhi, , Nasser Alzeidi, Khalid Day,
Wireless Sensor Network, Volume 10, pp 131-156; doi:10.4236/wsn.2018.107008

This work proposes a geographic routing protocol for UWSNs based on the construction of a 3D virtual grid structure, called Void-Avoidance Grid-based Multipath Position-based Routing (VA-GMPR). It consists of two main components, the multipath routing scheme and the grid-based void avoidance (GVA) mechanism for handling routing holes. The multipath routing scheme adopts node-disjoint routes from the source to the sink in order to enhance network reliability and load balancing. While the GVA mechanism handles the problem of holes in 3D virtual grid structure based on three techniques: Hole bypass, path diversion, and path backtracking. The performance evaluation of the VA-GMPR protocol was compared to a recently proposed grid-based routing protocol for UWSNs, called Energy-efficient Multipath Geographic Grid-based Routing (EMGGR). The results showed that the VA-GMPR protocol outperformed the EMGGR protocol in terms of packet delivery ratio, and end-to end-delay. However, the results also showed that the VA-GMPR protocol exhibited higher energy consumption compared to EMGGR.
Kalpana A. Kulkarni, Madhukar S. Zambare
Wireless Sensor Network, Volume 10, pp 59-69; doi:10.4236/wsn.2018.103003

Emergence of environmental issues such as air pollution has greatly required the need for robust, cheap, operationally adaptable, and smart monitoring systems. The proposed work describes a study of how the household plants are helpful in purifying the environment. Air pollution monitoring system has been developed using Wireless Sensor Network (WSN). Sensor nodes and embedded system are used for monitoring air quality. The monitoring system consists of sensor nodes, base station and PC for data processing, storage, and presentation. Once data is collected at PC, it is then compiled and presented on web server.
, Gijs Dubbelman, , Elena Talnishnikh, Heinrich J. Wortche, Jan W. M. Bergmans
Wireless Sensor Network, Volume 10, pp 1-39; doi:10.4236/wsn.2018.101001

A novel type of application for the exploration of enclosed or otherwise difficult to access environments requires large quantities of miniaturized sensor nodes to perform measurements while they traverse the environment in a “go with the flow” approach. Examples of these are the exploration of underground cavities and the inspection of industrial pipelines or mixing tanks, all of which have in common that the environments are difficult to access and do not allow position determination using e.g. GPS or similar techniques. The sensor nodes need to be scaled down towards the millimetre range in order to physically fit through the narrowest of parts in the environments and should measure distances between each other in order to enable the reconstruction of their positions relative to each other in offline analysis. Reaching those levels of miniaturization and enabling reconstruction functionality requires: 1) novel reconstruction algorithms that can deal with the specific measurement limitations and imperfections of millimetre-sized nodes, and 2) improved understanding of the relation between the highly constraint hardware design space of the sensor nodes and the reconstruction algorithms. To this end, this work provides a novel and highly robust sensor swarm reconstruction algorithm and studies the effect of hardware design trade-offs on its performance. Our findings based on extensive simulations, which push the reconstruction algorithm to its breaking point, provide important guidelines for the future development of millimetre-sized sensor nodes.
Tyler Horton, , Craig Prather, John Manobianco,
Wireless Sensor Network, Volume 10, pp 93-101; doi:10.4236/wsn.2018.104005

The need for higher spatial/temporal resolution in-situ atmospheric sensing has been established by both weather and climate researchers. In order to address this need, an airborne wireless sensor network called GlobalSense is currently being developed. GlobalSense is based on low-cost airborne probes that collect environmental data as they fall slowly through the atmosphere and on portable base stations that receive the data being collected. This paper presents an overview of this GlobalSense system as well as preliminary results from ground-based system testing.
Batur Alp AKGÜL, Muhammet Fatih Hasoğlu, Bülent Haznedar
Wireless Sensor Network, Volume 10, pp 41-58; doi:10.4236/wsn.2018.102002

Advancing technology has enabled the production of smaller, more energy efficient and cheaper electronic components. Therefore, previously existing many computer and electronics science-engineering ideas have become feasible. One of them is the technology of wireless sensor networks (WSNs), which has become the realization of the necessary technical requirements applicable today with low energy consumption. First, the sensing tasks and the potential sensor networks applications have explored, and reviews of factors influencing the design of sensor networks have provided. Then, the communication architectures for sensor networks have been outlined. PIC-based microcontrollers have used in the design of the sensor nodes. The design of the sensor node has supported with ultra-low power nanowatt technology for very low-cost design. Processing, memory and wireless communication units have integrated on to the sensor nodes and sensors to be used in the designed system which have allowed to be connected to any kind of sensor node. The designed sensor node’s operating system has written with the PIC C language, and PIC operating system has allowed different features such as measuring humidity, temperature, light sensitive and smoke sensor. Computer software has developed for data that can be recorded and monitored from a central location. Decision-making unit has created in the software algorithm and hardware modules for the implementation of decisions taken by the developed sensor nodes. Developed PIC-based sensor nodes have supported a unique voltage unit with renewable energy sources such as solar panel, rechargeable battery, and supercapacitor for energy production and saving. The results of this study are expected to be helpful for the development of WSN especially with renewable energy sources.
Salick Diagne, Thierry Val, ,
Wireless Sensor Network, Volume 10, pp 103-117; doi:10.4236/wsn.2018.105006

The rapid evolution of technology in the field of wireless telecommunications and micro components using MEMS technologies (Micro-electromechanical systems) has contributed to the expansion and rapid development of wireless sensor networks (WSN). This rapid development has contributed to the appearance of sensor and actuator networks (WSAN) or even to the Internet of Things with DL-IoT (Device Layer-Internet of Things). This rapid evolution of WSN is due to the enthusiasm generated by this last in industry and research. This new technology is used in several applications, particularly in the outdoor location of communicating nodes. The process of distance calculation between nodes (ranging) is a primordial phase for a precise location of these nodes. This paper presents the result of measurements does with three ranging protocols (TWR, TWR_Skew and SDS-TWR) implemented on DecaWiNo nodes. DecaWiNo nodes use the Ultra-Wide Band (UWB) radio links, proposed by the IEEE 802.15.4 standard amendment of the year 2007, which provides a high-performance ranging by ToF (Time of Flight) [1] [2]. The results are very promising with precision errors of the order of 50 cm over 20 meters.
C. Delebarre, T. Pujolle, G. Cousin, A. Domon, J. Froux, J. Jourdan
Wireless Sensor Network, Volume 10, pp 119-130; doi:10.4236/wsn.2018.106007

This paper presents a new wireless system for the measurement of CO2 gas concentration for indoor and outdoor purposes based on low cost Non Dispersive Infrared sensors. The system has been implemented on a printed circuit board in order to obtain different aspects of the air pollution. Some experiments were achieved to evaluate the total system combined with an android application on a smartphone. Different tests were realized in a closed room nearly filled with students and also directly while driving on the road. Good results were obtained allowing a future use for air pollution mapping using numerous amounts of sensors inside vehicles.
Jagath C. Ekanayake, Carolyn B. Hedley
Wireless Sensor Network, Volume 10, pp 71-92; doi:10.4236/wsn.2018.104004

Current advances in connected sensor technologies for near real-time environmental monitoring are transforming the quality of information provision to land managers. This “Third Industrial Revolution” that connects digital sensor data analytics with adaptive services aims to transform data processing for timely decision support. The information is needed to improve irrigation scheduling, because global demand for food relies heavily on irrigation and global freshwater resources are diminishing. Previously, practitioners used visual indicators, infrequent measurements or predictive water balance models to estimate irrigation schedules. Visual indicators and infrequent measurements are approximate, and predictive models require many inputs so that likely cumulative errors cause inaccuracies in scheduling. In contrast, wireless sensor networks enable near real-time continuous measurement of soil moisture at targeted positions providing the site-specific information required for precision irrigation scheduling and efficient freshwater management. This paper describes and compares the structure, build and implementation of Crossbow, DigiMesh, and LoRa systems to deliver information on spatio-temporal soil water status and crop stress to practitioners over smart phones and webpages to improve management of irrigated land. Our study found that the newer LoRA system has advantages over the other systems, especially on flat land, with furthest node range of >10 km and advanced communication protocols that can penetrate dense vegetation. The mesh networking of the DigiMesh and Crossbow systems was preferred in hilly terrain to communicate around hills, and allows easy expansion of the network. The Crossbow system is simpler to install but presents difficulties for third party sensor integration. All systems allowed a step change in our ability to track dynamic changes in soil hydraulic properties and crop stress, to improve irrigation water use efficiency.
Hakan Koyuncu, Baki Koyuncu
Wireless Sensor Network, Volume 9, pp 239-249; doi:10.4236/wsn.2017.98013

RFID technology is one of the important technologies to determine the object locations. Distances are calculated with respect to calibration curves of RSSI amplitudes. The aim of this study is to determine the 2D position of mobile objects in the indoor environment. The importance of the work is to show that localization by using Artificial Neural Network plus Kalman Filtering is more accurate than using classical KNN method. An indoor wireless sensing network is established with strategically stationed RFID transmitter nodes and a mobile object with a RFID receiver node. A fingerprint map is generated and K-Nearest Neighbourhood algorithm (KNN) is deployed to calculate the object locations. Fingerprint coordinates and RSS values received at these coordinates are deployed to set up an Artificial Neural Network (ANN). This network is used to determine the unknown object locations by using RSS values received at these locations. The accuracy of object localization is found to be better with ANN technique than KNN technique. Object coordinates, determined with ANN technique, are subjected to Kalman filtering. The results show that localization accuracies are improved and localization error distances are reduced by 46% with the deployment of ANN + Kalman Filtering.
Oran Sharon, Yaron Alpert
Wireless Sensor Network, Volume 9, pp 250-273; doi:10.4236/wsn.2017.98014

The new IEEE 802.11 standard, IEEE 802.11ax, has the challenging goal of serving more Uplink (UL) traffic and users as compared with his predecessor IEEE 802.11ac, enabling consistent and reliable streams of data (average throughput) per station. In this paper we explore several new IEEE 802.11ax UL scheduling mechanisms and compare between the maximum throughputs of unidirectional UDP Multi Users (MU) triadic. The evaluation is conducted based on Multiple-Input-Multiple-Output (MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) transmission multiplexing format in IEEE 802.11ax vs. the CSMA/CA MAC in IEEE 802.11ac in the Single User (SU) and MU modes for 1, 4, 8, 16, 32 and 64 stations scenario in reliable and unreliable channels. The comparison is conducted as a function of the Modulation and Coding Schemes (MCS) in use. In IEEE 802.11ax we consider two new flavors of acknowledgment operation settings, where the maximum acknowledgment windows are 64 or 256 respectively. In SU scenario the throughputs of IEEE 802.11ax are larger than those of IEEE 802.11ac by 64% and 85% in reliable and unreliable channels respectively. In MU-MIMO scenario the throughputs of IEEE 802.11ax are larger than those of IEEE 802.11ac by 263% and 270% in reliable and unreliable channels respectively. Also, as the number of stations increases, the advantage of IEEE 802.11ax in terms of the access delay also increases.
Abdullah Alshahrani, Nader M. Namazi, Majed Abdouli, Ahmed S. Alghamdi
Wireless Sensor Network, Volume 9, pp 311-332; doi:10.4236/wsn.2017.99018

The particularities of Wireless Sensor Networks require specially designed protocols. Nodes in these networks often possess limited access to energy (usually supplied by batteries), which imposes energy constraints. Additionally, WSNs are commonly deployed in monitoring applications, which may intend to cover large areas. Several techniques have been proposed to improve energy-balance, coverage area or both at the same time. In this paper, an alternative solution is presented. It consists of three main components: Fuzzy C-Means for network clustering, a cluster head rotation mechanism and a sleep scheduling algorithm based on a modified version of Particle Swarm Optimization. Results show that this solution is able to provide a configurable routing protocol that offers reduced energy consumption, while keeping highcoverage area.
Arun Kumar, , Kai Juan Wong,
Wireless Sensor Network, Volume 9, pp 25-72; doi:10.4236/wsn.2017.91003

Recently, location-based routings in wireless sensor networks (WSNs) are attracting a lot of interest in the research community, especially because of its scalability. In location-based routing, the network size is scalable without increasing the signalling overhead as routing decisions are inherently localized. Here, each node is aware of its position in the network through some positioning device like GPS and uses this information in the routing mechanism. In this paper, we first discuss the basics of WSNs including the architecture of the network, energy consumption for the components of a typical sensor node, and draw a detailed picture of classification of location-based routing protocols. Then, we present a systematic and comprehensive taxonomy of location-based routing protocols, mostly for sensor networks. All the schemes are subsequently discussed in depth. Finally, we conclude the paper with some insights on potential research directions for location-based routing in WSNs.
Monica Laxman Uttarwar, Arun Kumar,
Wireless Sensor Network, Volume 9, pp 302-310; doi:10.4236/wsn.2017.98017

Nowadays, Global Positioning Systems (GPS) receivers are used for outdoor navigation, which are the part of recent smartphones and tablet devices. However, GPS is not suitable for indoor navigations due to its signal limitations which are blocked by ceiling and walls. Indoor navigation can be achieved through a mobile phone using a recent technology that utilizes Bluetooth, namely beacons. Beacons are small transmitters, run on Bluetooth Low Energy (BLE) technology, used as a point of reference for mobile devices and they can detect a Bluetooth enabled device once it enters its transmission range. In this paper, we present BeaLib: a beacon assisted indoor navigation technique for smart libraries. The proposed indoor navigation technique can also be used for other applications such as offices, retails, airports, hospitality, and education. For experimentation, beacons are placed in a library and a Bluetooth enabled smartphone is used to install a digital library application (App) which communicates with the beacons. The result shows that when the smartphone comes in the range of a beacon, it shows the information related to the book on the smartphone screen.
Wireless Sensor Network, Volume 9, pp 166-177; doi:10.4236/wsn.2017.95009

With the ever-increasing range of video and audio applications in portable handheld devices, demand for high throughput in Wi-Fi networks is escalating. In this paper we introduce several novel features defined in next generation WLAN, termed as IEEE 802.11ax standard, and compare between the maximum throughputs received in IEEE 802.11ax and IEEE 802.11ac in a scenario where the AP continuously transmits to one station in the Single User mode. The comparison is done as a function of the modulation/coding schemes in use. In IEEE 802.11ax we consider two levels of frame aggregation. IEEE 802.11ax outperforms IEEE 802.11ac by about 29% and 48% in reliable and unreliable channels respectively.
Yuming Mo, Lianming Du, Bingbing Qu, Bo Peng, Jie Yang
Wireless Sensor Network, Volume 9, pp 178-188; doi:10.4236/wsn.2017.95010

In most MEMS devices, the moving micro-structures are surrounded by air which significantly affects their dynamics behaviors. The correct prediction of the squeeze-film air damping ratio is essential in MEMS (Micro-Electro-Me- chanical System) devices design. In the paper, a static test is proposed to measure the squeeze-film air damping ratios of capacitive MEMS accelerometer under different pressures. The unsealed chip of capacitive accelerometer is placed in vacuum extraction equipment and an open loop circuit is developed to apply step signal in the test. By charging the pressure and measuring the overshoot Mp and the settling time ts from the time response of the system, the damping ratio ξ under different pressures can be calculated. Finite element method (FEM) based on the modified Reynolds equation is utilized to simulate the transient response of the micro-structure. Good correlation between experiment and FEM analysis is obtained. The proposed static test in this paper provides a new method to more easily measure the dynamic performances of micro-structures under various pressures.
Gopal Chand Gautam, Narottam Chand
Wireless Sensor Network, Volume 9, pp 145-165; doi:10.4236/wsn.2017.95008

Time synchronization is one of the important aspects in wireless sensor networks. Time synchronization assures that all the sensor nodes in wireless sensor network have the same clock time. There are various applications such as seismic study, military applications, pollution monitoring where sensor nodes require synchronized time. Time synchronization is mandatory for many wireless sensor networks protocols such as MAC protocols and also important for TDMA scheduling for proper duty cycle coordination. Time synchronization is a stimulating problem in wireless sensor networks because each node has its own local clock which keeps on varying due to variation in the oscillator frequency. The oscillator frequency is time varying due to ambient conditions which leads to re-synchronization of nodes time and again. This re-synchronization process is energy consuming whereas energy is constraints in WSN. This paper proposes a novel cluster based time synchronization technique for wireless sensor networks in which cluster head rotation is based on minimum clock offset. Simulation results based on energy analysis of the proposed model demonstrate that proposed novel cluster based time synchronization technique reduces the energy consumption and also the synchronization error compared with other existing protocols.
Xiao Shao, Harry Leib
Wireless Sensor Network, Volume 9, pp 205-237; doi:10.4236/wsn.2017.97012

The increasing interest for wireless communication services and scarcity of radio spectrum resources have created the need for a more flexible and efficient usage of the radio frequency bands. Cognitive Radio (CR) emerges as an important trend for a solution to this problem. Spectrum sensing is a crucial function in a CR system. Cooperative spectrum sensing can overcome fading and shadowing effects, and hence increase the reliability of primary user detection. In this paper we consider a system model of a dedicated detect-andforward wireless sensor network (DetF WSN) for cooperative spectrum sensing with k-out-of-n decision fusion in the presence of reporting channels errors. Using this model we consider the design of a spatial reuse media access control (MAC) protocol based on TDMA/OFDMA to resolve conflicts and conserve resources for intra-WSN communication. The influence of the MAC protocol on spectrum sensing performance of the WSN is a key consideration. Two design approaches, using greedy and adaptive simulated annealing (ASA) algorithms, are considered in detail. Performance results assuming a grid network in a Rician fading environment are presented for the two design approaches.
Albert S. Lutakamale, Shubi Kaijage
Wireless Sensor Network, Volume 9, pp 274-289; doi:10.4236/wsn.2017.98015

This paper proposes a wildfire monitoring and detection system based on wireless sensor network. This system detects fire by monitoring surrounding temperature, humidity and smoke. Once fire is detected, a warning message containing probable location of that fire is immediately sent to the responsible authority over cellular network. In order for the system to be more effective, communities living near forests or national parks can send warning messages through the same system to the responsible authority using their mobile handsets once they witness wildfire or illegal activities. For the system to be fully functional, the only requirement is the availability of cellular network coverage in forests or national parks to enable short message services to take place. The system prototype is developed using Arduino microcontroller, several sensors to detect temperature, relative humidity and smoke as well as wireless network connection modules. At the control center Telerivet messaging platform is used to design the messaging service. The experimental results justify the capability of the proposed system in detecting wildfire in real time.
Shivkumar S. Jawaligi, G. S. Biradar
Wireless Sensor Network, Volume 9, pp 117-144; doi:10.4236/wsn.2017.94007

Recently, the exponential rise in communication system demands has motivated global academia-industry to develop efficient communication technologies to fulfill energy efficiency and Quality of Service (QoS) demands. Wireless Sensor Network (WSN) being one of the most efficient technologies possesses immense potential to serve major communication purposes including civil, defense and industrial purposes etc. The inclusion of sensor-mobility with WSN has broadened application horizon. The effectiveness of WSNs can be characterized by its ability to perform efficient data gathering and transmission to the base station for decision process. Clustering based routing scheme has been one of the dominating techniques for WSN systems; however key issues like, cluster formation, selection of the number of clusters and cluster heads, and data transmission decision from sensors to the mobile sink have always been an open research area. In this paper, a robust and energy efficient single mobile sink based WSN data gathering protocol is proposed. Unlike existing approaches, an enhanced centralized clustering model is developed on the basis of expectation-maximization (EEM) concept. Further, it is strengthened by using an optimal cluster count estimation technique that ensures that the number of clusters in the network region doesn’t introduce unwanted energy exhaustion. Meanwhile, the relative distance between sensor node and cluster head as well as mobile sink is used to make transmission (path) decision. Results exhibit that the proposed EEM based clustering with optimal cluster selection and optimal dynamic transmission decision enables higher throughput, fast data gathering, minima delay and energy consumption, and higher efficiency
Yu Song, , Ralf Volker Binsack
Wireless Sensor Network, Volume 9, pp 103-115; doi:10.4236/wsn.2017.93006

In this article, a routing protocol EARP (Energy Aware Routing Protocol) with the terminal node is proposed, to deal with the impact of the limited energy resources of Cognitive Radio Networks on the whole network routing. The protocol allows choosing the route from the neighbor nodes in different transmission paths, according to energy consumption of a single node and the full path. If the path breaks, the protocol will increase local routing maintenance strategy. It effectively reduces the retransmission caused by the situation, and improves the routing efficiency. It also can prevent the link transmission process selecting the fault route due to the energy depletion. Through simulation experiments compared with the LEACH (Low Energy Adaptive Clustering Hierarchy) routing protocol, the results showed that in the same experimental environment, the proposed EARP could obviously balance the load, protect low energy nodes, prolong the network survival time and reduce packet loss rate and packet delay of data delivery. So it can improve the energy consumption of sensing node and provide routing capabilities.
Karuna Babber, Rajneesh Randhawa
Wireless Sensor Network, Volume 9, pp 189-203; doi:10.4236/wsn.2017.96011

We consider the extension of network lifetime of battery driven wireless sensor networks by splitting the sensing area into uniform clusters and implementing heterogeneous modulation schemes at different members of the clusters. A cross-layer optimization has been proposed to reduce total energy expenditure of the network; at network layer, routing is done through uniform clusters; at MAC layer, each sensor node of the cluster is assigned fixed or variable time slots and at physical layer different member of the clusters is assigned different modulation techniques. MATLAB simulation proved substantial network lifetime gains.
Gopal Chand Gautam, Narottam Chand Kaushal
Wireless Sensor Network, Volume 9, pp 1-15; doi:10.4236/wsn.2017.91001

Raqeebir Rab, Shaheed Ahmed Dewan Sagar, Nazmus Sakib, Ahasanul Haque, Majedul Islam, Ashikur Rahman
Wireless Sensor Network, Volume 9, pp 73-86; doi:10.4236/wsn.2017.92004

Reducing number of forwarding nodes is the main focus of any broadcasting algorithm designed for ad-hoc wireless networks. All reliable broadcasting techniques can be broadly classified under proactive and reactive approaches. In proactive approach, a node selects a subset of its neighbors as forwarding node and announces the forwarding node list in the packet header during broadcast. On the other hand, no such forwarding list is generated in reactive approach. Rather, a node (cognitively) determines by itself whether to forward the packet or not based on neighbor information. Dominant pruning and Self-pruning are two example techniques that fall under proactive and reactive approach respectively. Between the two methods, dominant pruning shows better performance than self-pruning in reducing number of forwarding nodes as they work with extended neighbor knowledge. However, appended forwarding node list increases message overhead and consumes more bandwidth. As a result, the approach becomes non-scalable in large networks. In this paper, we propose a reactive broadcasting technique based on self-pruning. The proposed approach dubbed as “Improved Self-pruning based Broadcasting (ISB)” algorithm completes the broadcast with smaller packet header (i.e., with no overhead) but uses extended neighbor knowledge. Simulation results show that ISB outperforms dominant pruning and self-pruning. Furthermore, as the network gets more spread and denser, ISB works remarkably well.
Wireless Sensor Network, Volume 9, pp 355-383; doi:10.4236/wsn.2017.910020

The new IEEE 802.11ax standard is aimed to serve many users while enabling every station to transmit a consistent stream of data without interruption. In this paper we evaluate the upper bound on the throughput of a Downlink IEEE 802.11ax channel using the Single User (SU) mode and using the Multi User Multiple-Input-Multiple-Output (MU-MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) mode. We compare between IEEE 802.11ax and IEEE 802.11ac for the case of 1, 4, 8, 16, 32 and 64 stations in different Modulation/Coding schemes (MCS) and different transmission windows’ sizes, 64 and 256 frames in IEEE 802.11ax. IEEE 802.11ax outperforms IEEE 802.11ac in the SU and MU modes by 52% and 74% in a reliable channel respectively, while in an unreliable channel the improvements are by 59% and 103% respectively. Also, in terms of the access delay, the advantage of IEEE 802.11ax increases as the number of stations increases.
Khadije Rahimkhani, Fatemeh Forouzesh
Wireless Sensor Network, Volume 9, pp 333-353; doi:10.4236/wsn.2017.99019

One of the most important issues of wireless sensor networks is how to transfer information from the network nodes to a base station and choose the best possible path for this purpose. Choosing the best path can be based on different factors such as energy consumption, response time, delay, and data transfer accuracy. Increasing the network lifetime is the most challenging problem. One of the latest energy-aware routing methods is to use the harmony search algorithm in the small-scale sensor networks. The aim of this study is to introduce the harmony search algorithm as a successful metaheuristic algorithm for wireless sensor network routing in order to increase the lifetime of such networks. This study is intended to improve the objective function for energy efficiency in the harmony search algorithm to establish balance between the network energy consumption and path length control. Therefore, it is necessary to choose the initial energy of each node randomly from a certain range as the path energy consumption should be low to choose a path which can consider the residual energy. In other words, a path should be chosen to establish balance between the network energy consumption and the minimum residual energy. The simulation results indicate that the proposed objective function provides a longer lifetime by 26.12% compared with EEHSBR.
Yona Zakaria, Kisangiri Michael
Wireless Sensor Network, Volume 9, pp 290-301; doi:10.4236/wsn.2017.98016

This paper presents a prototype of an Integrated Cloud-Based Wireless Sensor Network (WSN) developed to monitor pH, conductivity and dissolved oxygen parameters from wastewater discharged into water sources. To provide realtime online monitoring and Internet of Things (IoT) capability, the system collects and uploads sensor data to ThingSpeak cloud via GPRS internet connectivity with the help of AT commands in combination with HTTP GET method. Moreover, the system sends message alert to the responsible organ through GSM/GPRS network and an SMS gateway service implemented by Telerivet mobile messaging platform. In this prototype, Telerivet messaging platform gives surrounding communities a means of reporting observed or identified water pollution events via SMS notifications.
Annu Ghotra
Wireless Sensor Network, Volume 9, pp 16-24; doi:10.4236/wsn.2017.91002

Energy conservation is becoming the main critical issue in wireless sensor network and also the main research area for most of the researchers. For improving the energy efficiency, sink mobility is used with constrain path in wireless sensor network. In order to solve these optimization problems, inter cluster Ant Colony Optimization Algorithm (ACO) is used with mobile sink (MS) and rendezvous nodes (RN). The proposed algorithm will improve 30% more network lifetime than the existing algorithm and prompts high accurate delivery of packets in highly dense network. a
Adeniran Ademuwagun, Verdicchio Fabio
Wireless Sensor Network, Volume 9, pp 87-101; doi:10.4236/wsn.2017.92005

As much as accurate or precise position estimation is always desirable, coarse accuracy due to sensor node localization is often sufficient. For such level of accuracy, Range-free localization techniques are being explored as low cost alternatives to range based localization techniques. To manage cost, few location aware nodes, called anchors are deployed in the wireless sensor environment. It is from these anchors that all other free nodes are expected to estimate their own positions. This paper therefore, takes a look at some of the foremost Range-free localization algorithms, detailing their limitations, with a view to proposing a modified form of Centroid Localization Algorithm called Reach Centroid Localization Algorithm. The algorithm employs a form of anchor nodes position validation mechanism by looking at the consistency in the quality of Received Signal Strength. Each anchor within the vicinity of a free node seeks to validate the actual position or proximity of other anchors within its vicinity using received signal strength. This process mitigates multipath effects of radio waves, particularly in an enclosed environment, and consequently limits localization estimation errors and uncertainties. Centroid Localization Algorithm is then used to estimate the location of a node using the anchors selected through the validation mechanism. Our approach to localization becomes more significant, particularly in indoor environments, where radio signal signatures are inconsistent or outrightly unreliable. Simulated results show a significant improvement in localization accuracy when compared with the original Centroid Localization Algorithm, Approximate Point in Triangulation and DV-Hop.
Mukhdeep Singh Manshahia, Mayank Dave, Satya Bir Singh
Wireless Sensor Network, Volume 8, pp 229-241; doi:10.4236/wsn.2016.811018

Energy conservation and congestion control are widely researched topics in Wireless Sensor Networks in recent years. The main objective is to develop a model to find the optimized path on the basis of distance between source and destination and the residual energy of the node. This paper shows an implementation of nature inspired improved Bat Algorithm to control congestion in Wireless Sensor Networks at transport layer. The Algorithm has been applied on the fitness function to obtain an optimum solution. Simulation results have shown improvement in parameters like network lifetime and throughput as compared with CODA (Congestion Detection and Avoidance), PSO (Particle Swarm Optimization) algorithm and ACO (Ant Colony Optimization).
Mohammed Ezz El Dien, Aliaa A. A. Youssif,
Wireless Sensor Network, Volume 8, pp 25-36; doi:10.4236/wsn.2016.83003

Wireless Multimedia Sensor Networks (WMSNs), is a network of sensors, which are limited in terms of memory, computing, bandwidth, and battery lifetime. Multimedia transmission over WSN requires certain QoS guarantees such as huge amount of bandwidth, strict delay and lower loss ratio that makes transmitting multimedia is a complicated task. However, adopting cross-layer approach in WMSNs improves quality of service of WSN under different environmental conditions. In this work, an energy efficient and QoS aware framework for transmitting multimedia content over WSN (EQWSN) is presented, where packet, queue and path scheduling were introduced. It adapts the application layer parameter of video encoder to current wireless channel state, and drops less important packets in case of network congestion according to packet type. Finally, the path scheduling differentiates packets types/priority and route them through different paths with different QoS considering network lifetime. Simulation results show that the new scheme EQWSN transmits video quality with QoS guarantees in addition to prolonging network lifetime.
Sara Nouh, Nada Elgaml, Nora Ali, Ahmed Khattab, , Hassanein Amer
Wireless Sensor Network, Volume 8, pp 85-92; doi:10.4236/wsn.2016.86009

Wireless Sensor Networks (WSN) have recently become one of the major research areas in the wireless communication field and are implemented in a variety of applications. One of these applications that will be tackled in this paper is monitoring electromagnetic (EM) pollution that is mostly caused by a variety of wireless devices that we use in our daily life. This paper presents a generic algorithm that uses a WSN to monitor EM hazardous emissions and reports variation caused by four violators. Additionally it calculates the network’s lifetime and simultaneously studies the effect of random parameters and their distributions on the network. Finally the different combinations of the random parameters and the altered distributions are compared together to achieve the combination that can prolong the network’s lifetime.
Mustafa El Gili Mustafa, Samani A. Talab
Wireless Sensor Network, Volume 8, pp 77-84; doi:10.4236/wsn.2016.85008

The paper presents the simulation results of the comparison of three Queuing Mechanisms, First in First out (FIFO), Priority Queuing (PQ), and Weighted Fair Queuing (WFQ). Depending on their effects on the network’s Routers, the load of any algorithm of them over Router’s CPUs and memory usage, the delay occurred between routers when any algorithm has been used and the network application throughput. This comparison explains that, PQ doesn’t need high specification hardware (memory and CPU) but when used it is not fair, because it serves one application and ignore the other application and FIFO mechanism has smaller queuing delay, otherwise PQ has bigger delay.
Nour Brinis, Leila Azouz Saidane
Wireless Sensor Network, Volume 8, pp 1-12; doi:10.4236/wsn.2016.81001

Using the Wireless Sensor Networks WSNs in a wide variety of applications is currently considered one of the most challenging solutions. For instance, this technology has evolved the agriculture field, with the precision agriculture challenge. In fact, the cost of sensors and communication infrastructure continuously trend down as long as the technological advances. So, more growers dare to implement WSN for their crops. This technology has drawn substantial interests by improving agriculture productivity. The idea consists of deploying a number of sensors in a given agricultural parcel in order to monitor the land and crop conditions. These readings help the farmer to make the right inputs at the right moment. In this paper, we propose a complete solution for gathering different type of data from variable fields of a large agricultural parcel. In fact, with the in-field variability, adopting a unique data gathering solution for all kinds of fields reveals an inconvenient approach. Besides, as a fault-tolerant application, precision agriculture does not require a high precision value of sensed data. So, our approach deals with a context aware data gathering strategy. In other words, depending on a defined context for the monitored field, the data collector will decide the data gathering strategy to follow. We prove that this approach improves considerably the lifetime of the application.
Muhammad Shoaib Khan, , Marwah Almasri
Wireless Sensor Network, Volume 8, pp 13-23; doi:10.4236/wsn.2016.82002

The flexible use of sensors has made them an attractive device to be deployed in almost every field of life such as health, military and home. Recent advancement in electronics and wireless communications has witnessed the development of low cost-sensor devices. While wireless sensor networks (WSNs) are flexible to use and less costly, they need to be more energy-efficient as they are operated by the battery. Mostly they are deployed in harsh environments where it is very difficult to change the batteries frequently. Several medium access control (MAC) algorithms have been developed for the energy-efficient acquisition of the wireless channel, however, none of them are satisfactory. In this paper, we proposed a medium access control algorithm called MAC-PE. MAC-PE is based on the concept of prioritized frames where prioritized frames are transmitted urgently. In addition, it uses scheduled-based MAC instead of accessing channel randomly. We found MAC-PE (Power-Efficient MAC) was efficient in terms of power consumption without sacrificing on the performance using NS-2.
Jaspreet Kaur Kohli, Amol Potgantwar
Wireless Sensor Network, Volume 8, pp 69-75; doi:10.4236/wsn.2016.84007

Indoor positioning systems (IPSs) have been intended to provide position information of persons and devices. Higher user percentage of handheld devices such as tablets or mobile phones had led to the development of a number of indoor positioning systems. In this research a work on a real time portable RFID indoor positioning device such as on smartphone will be performed. The personal networks will be designed to meet the users’ needs and interconnect users’ devices equipped with different communications technologies in various places to form one network for better result. Radio frequency identification (RFID) with directional antenna has proved its potential for locating objects in indoor environment. Hence, the proposed device idea will be used to exploit various unknown locations in an indoor environment such as college campus; this interpretation will rely on Wireless LAN, Received Signal Strength values from Access Points (AP) in specific mentioned arenas; these APs will be monitored constantly by RFID with directional antenna (DA) and handheld devices. For obtaining the better results from existing devices, algorithms of Range Estimation are proposed, which can be used on various handheld devices for locating indoor objects.
Piyush Charan, Tahsin Usmani, Rajeev Paulus, Syed Hasan Saeed
Wireless Sensor Network, Volume 8, pp 166-175; doi:10.4236/wsn.2016.88014

Over the past years, wireless sensor systems have picked up a global consideration from both the researchers and the genuine clients. It includes a large number of sensing devices, some computing techniques and communication with limited power supplies and processing abilities which collectively work to fulfill a large sensing task. IEEE 802.15.4/ZigBee based Wireless Sensor Networks raise a few issues like Energy Scavenging for the limited power supply. Accordingly good functioning of such system relies upon energies of the wireless motes. This paper presents two analytical models which demonstrate and predict the QoS in terms of throughput, jitter, average end-to-end delay and energy consumption. These two distinct network models based on IEEE 802.15.4 are cluster-based and grid-based, and are simulated using QualNet v 6.1 Simulator.
Jean Mickael Lebreton, , Nour Murad, Richard Lorion
Wireless Sensor Network, Volume 8, pp 176-190; doi:10.4236/wsn.2016.88015

Wake-up radio (WuR) system is often presented as the best candidate for replacing traditional duty cycled Medium Access Control (MAC) protocols in Wireless Sensor Networks (WSNs). The Double Radio (DoRa) protocol is a new MAC protocol for in-band WuR system with addressing capabilities. While the DoRa protocol improves the WSNs energy efficiency, it still suffers from an overhearing problem when the WuR system is very often requested. The WuR wastes a noticeable amount of energy when overhearing to wake-up demand intended to other nodes, but it is neither measured nor solved in other works. In this paper, an adaptive duty-cycled DoRa (DC-DoRa) is then proposed to solve the overhearing problem. The primary concept of the work is to enable the WuR functionality before the node is addressed and to disable the WuR after the node sent data. Extensive simulations under OMNeT++ using real input parameters are then performed to show the significant energy-savings through the two protocols and the nearly suppression of overhearing with DC-DoRa. In fact, the mean power consumption is three-order below using the DoRa protocol compared to traditional MAC protocols. While overhearing can represent up to 93% of the WuR energy consumption with the DoRa protocol, it is reduced to only 1% with the DC-DoRa protocol.
Wireless Sensor Network, Volume 8, pp 107-136; doi:10.4236/wsn.2016.87011

This paper suggests a new model for the transmission of Transmission Control Protocol (TCP) traffic over IEEE 802.11 using the new features of IEEE 802.11ac. The paper examines the first step in this direction and as such we first consider a single TCP connection, which is typical in a home environment. We show that when the IEEE 802.11ac MAC is aware of QoS TCP traffic, using Reverse Direction improves the TCP Goodput in tens of percentages compared to the traditional contention based channel access. In an error-free channel this improvement is 20% while in an error-prone channel the improvement reaches 60% also using blind retransmission of frames. In our operation modes we also assume the use in Two-Level aggregation scheme, the Automatic Repeat-Request (ARQ) protocol of the IEEE 802.11ac MAC layer, the data rates and the four Access Categories defined in this standard.
Sudhir Chitnis, , Arvind Shaligram
Wireless Sensor Network, Volume 8, pp 61-68; doi:10.4236/wsn.2016.84006

Home security should be a top concern for everyone who owns or rents a home. Moreover, safe and secure residential space is the necessity of every individual as most of the family members are working. The home is left unattended for most of the day-time and home invasion crimes are at its peak as constantly monitoring of the home is difficult. Another reason for the need of home safety is specifically when the elderly person is alone or the kids are with baby-sitter and servant. Home security system i.e. HomeOS is thus applicable and desirable for resident’s safety and convenience. This will be achieved by turning your home into a smart home by intelligent remote monitoring. Smart home comes into picture for the purpose of controlling and monitoring the home. It will give you peace of mind, as you can have a close watch and stay connected anytime, anywhere. But, is common man really concerned about home security? An investigative study was done by conducting a survey to get the inputs from different people from diverse backgrounds. The main motivation behind this survey was to make people aware of advanced HomeOS and analyze their need for security. This paper also studied the necessity of HomeOS investigative study in current situation where the home burglaries are rising at an exponential rate. In order to arrive at findings and conclusions, data were analyzed. The graphical method was employed to identify the relative significance of home security. From this analysis, we can infer that the cases of having kids and aged person at home or location of home contribute significantly to the need of advanced home security system. At the end, the proposed system model with its flow and the challenges faced while implementing home security systems are also discussed.
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