DW-MAC

The problem of idle listening is one of the most significant sources of energy consumption in wireless sensor nodes. Many techniques have been proposed based on duty cycling to reduce this idle listening. This paper presents Adaptive Scheduling Predictive-Wakeup MAC (AS-PW-MAC), a new MAC protocol based on asynchronous duty cycling. AS-PW-MAC introduces RTE and RAS messages for pending data transmission. RTE and RAS are beneficial for varying traffic loads. We evaluate the performance of AS-PW-MAC through detailed ns-2 simulation and compare it to RI-MAC and PW-MAC, two well-known MAC protocols. Our evaluation includes clique, grid and random network scenarios. In all experiments, AS-PW-MAC significantly out performs RI-MAC and PW-MAC protocols. AS-PW-MAC achieves higher packet delivery ratio under a wide range of traffic loads compared to RI-MAC and PW-MAC. Especially, when there are contending flows, such as bursty traffic or transmissions from hidden nodes, AS-PW-MAC significantly improves the packet delivery ratio and delivery latency. The delivery latency for AS-PW-MAC is less than 21% compared to RI-MAC and PW-MAC. In all experiments, AS-PW-MAC maintained approximately 100% packet delivery ratio.

Naturopathic approaches to weight loss in clinical practice – a mixed methods study

Cognitive radio systems are a smart approach to solve the problem of under-utilized spectrum of the licensed primary users (PUs). In order to gain a better quantitative insight of such systems, having a precise and comprehensive mathematical model of system throughput is vital. In this paper, we consider a set of PUs that are distributed in space based on Poisson point process (PPP) and demand for available spectrum. We determine the effect of these demands on the throughput of a single sensing secondary user (SU) under various channel requesting distributions and fading environment. In this context, we analytically derived the SU throughput in the presence of mutual interference due to imperfect detection of the SU in an OFDMA-based cognitive radio system. Moreover, the asymptotic behavior of the primary network is analytically studied under the asymptotic conditions such as higher traffic load and increasing transmit power. The results are critically investigated, formulated as theorems and compared with simulations. It is observed that analytical and simulation results are in perfect agreement. Furthermore, it is shown that with the increase in primary network transmit power, the average throughput of the SU increases and converges to a limit point. It is also proved that with the increase in primary network traffic load, the SU throughput decreases and converges to a limit point. Numerical results verify the validity of our model in capturing the effects of system specifications such as the channel requesting distributions and the traffic load on the SU throughput.

How to determine the source-visiting sequence among the target sensor nodes and manage the mobile agent (MA) effectively is the crucial problem in Mobile-Agent-based computing model for wireless sensor networks (WSNs). In this paper, we propose a novel improved Directed Diffusion-based MA mechanism (IDDMA) for WSNs. IDDMA uses an improved gradient generation algorithm to set up multiple optimal gradients among sensor nodes. The source nodes will subsequently send two distinct types of the exploratory data packet to implement the discovery of the sources and build the routing tables for the MA routing, respectively. Then, the MA in target region could choose its next-hop node dynamically according to the established routing table for MA in each source node and achieve the data fusion; finally it will return to the Sink. Simulation results show that the mechanism outperforms two existing routing protocols in end-to-end packet delay and average energy consumption.

Impact of queuing discipline on packet delivery latency in ad hoc networks

The purpose of the paper is to examine if public long term evolution (LTE) network is suitable for smart grid (SG) automatic metering usage, in a suburban scenario, without causing significant hindrance to typical LTE traffic. In addition, the same generalized suburban scenario is evaluated with a hybrid sensor - LTE network where wireless sensor network (WSN) cluster heads are also equipped with LTE remote terminal units (RTUs). The simulation topology is formed as a suburban area that consists of single RTU per apartment/house for SG traffic and an average 3.7 people per habitat, each with their user equipment, using one of the available carriers. Normal SG traffic is generated in both directions, uplink and downlink. The worst-case usage factor is considered as a power outage, where all SG meters in the area of influence simultaneously detect and attempt to report such a failure. Thus, emergency SG traffic is generated simultaneous by all RTUs. To alleviate the problem of the high momentary SG emergency traffic load, two distinct solutions are proposed and simulated. As the first solution, an artificial, up to one-second random delay is introduced in the transmission scheduling of emergency messages. The second solution applies low-power WSNs at the cluster level and cluster heads that contain both 802.15.4 and LTE communication interfaces, i.e., a hybrid sensor-LTE network. The simulation results show that both of the solutions that try to alleviate the high instantaneous traffic loads can reach the quality of service criteria for SG traffic without compromising other public LTE traffic. The deciding factor to use either pure LTE approach or a hybrid sensor-LTE network comes from non-functional requirements of the system.

Bluetooth Mesh is a recent SIG standard enabling the deployment of multi-hop Wireless Sensor Networks (WSNs) over Bluetooth Low Energy (BLE) communication links. The standard introduces many novel and interesting features in the Internet of Things (IoT) domain, such as the seamless integration among sensors and mobile and wearable devices, and the support for a wide range of different IoT application profiles. At the same time, fine-grained assessments of the performance are still needed to understand the potential of the technology. In this paper, we investigate the usage of Bluetooth Mesh solutions for the joint monitoring of indoor spaces and humans. Through the deployment of a test-bed, we evaluate the performance of Bluetooth Mesh WSNs under varying traffic loads and network sizes. In addition, by exploiting the short-range, multi-hop communications, we propose a procedure for the indoor localization of mobile devices and evaluate its accuracy. The results demonstrate that the technology supports reasonable delivery ratio under high traffic loads, however the network and localization performance sharply decreases when increasing the number of hops between the source and destination nodes.

This paper introduces a novel technique and mathematical formulation of two dimensional elastic footprint variations and adaptive sector configuration variations by using a hybrid adaptive amplitude control antenna array system. The antenna array system can control the elevation beam-widths from 6.84° to 13° and the azimuth beam-widths from 33° to 93° for obtaining the adaptive capacity and coverage. The work illustrates the application of the antenna array system in the energy efficient W-CDMA network. The antenna array half-power beam width variation is achieved by using the antenna array amplitude control and co-located multiple antenna array switching. The Node-Bs can adaptively switch to three, four, five, six and non uniform sector configurations with the antenna array beam width control and adaptive neighbor relations. Sector configurations will vary according to the pre-defined specific traffic loading percentages out of Node-B’s total channel capacity to reduce the energy consumption of the entire network. The paper introduces an adaptive footprint overlaps shifting technique, where the sector with less traffic load will expand its footprint towards the sector with higher traffic load and the sector with higher traffic load will shrink its footprint by maintaining a fixed footprint overlaps to improve the coverage and the capacity of the network. The footprints overlap shifting is applicable only for the active sector antennas facing each other. The results confirm that the proposed antenna array system outperforms the automatic tilt optimization and can control coverage, capacity and improve the energy efficiency of the W-CDMA network.

SummaryA wireless sensor network (WSN) is a network of spatially distributed autonomous sensor nodes that collaborate to monitor physical or environmental conditions, collect data, and transmit it to a sink node. WSNs have a wide range of applications across various domains due to their ability to provide real‐time data collection, remote monitoring, and data analysis. Still, in a WSN with a fixed sink, sensor nodes closer to the sink tend to have higher traffic loads because they forward data to nodes further away. This can lead to hotspots and uneven energy consumption. Introducing a mobile sink can distribute the traffic more evenly across the network, reducing congestion and balancing the energy consumption among nodes. Hence, this research proposes a novel WSN environment with a focus on energy‐efficient routing. The network is deployed using Voronoi‐based criteria to address network coverage issues. The clustering of nodes is employed using the proposed extended pelican optimization (ExPo) algorithm to improve network lifetime and energy efficiency, critical concerns in WSNs due to limited sensor node battery capacity. Cluster heads (CHs) aggregate and process data locally, reducing the energy needed for long‐range communication. Then, an energy‐efficient optimal sink placement (EEOSP) approach is used to optimize the placement of the mobile sink. The proposed system model is evaluated based on various metrics, including average residual energy, delay, network lifetime, packet delivery ratio, and throughput and acquired the values of 0.99 J, 3.68 ms, 99.55%, 99.55%, and 81 Mbps, respectively.

One of the most effective way to prevent unauthorized and corrupted message being forwarded in wireless sensor network. But there is high computational and communication overhead in addition to lack of scalability and resilience to node compromise attacks. So to address these issues, a polynomial-based scheme was recently introduced. However, this scheme and its extensions all have the weakness of a built-in threshold determined by the degree of the polynomial. when the number of messages transmitted is larger than this threshold, the adversary can fully recover the polynomial. In the existing system, an unconditionally secure and efficient source anonymous message authentication (SAMA) scheme is presented which is based on the optimal modified Elgamal signature (MES) scheme on elliptic curves. This MES scheme is secure against adaptive chosen-message attacks in the random oracle model. This scheme enables the intermediate nodes to authenticate the message so that all corrupted message can be detected and dropped to conserve the sensor power. While achieving compromise resiliency, flexible-time authentication and source identity protection, this scheme does not have the threshold problem. While enabling intermediate nodes authentication, this scheme allows any node to transmit an unlimited number of messages without suffering the threshold problem. But by using this method the black hole and gray hole attacks are detected but wormhole attack is doesn't detect. Because the wormhole attack is one of the harmful attacks which degrade the network performance. So, in the proposed system, one innovative technique is introduced which is called an efficient wormhole detection mechanism in the wireless sensor networks. In this method, considers the RTT between two successive nodes and those nodes' neighbor number which is needed to compare those values of other successive nodes. The identification of wormhole attacks is based on the two faces. The first consideration is that the transmission time between two wormhole attack affected nodes is considerable higher than that between two normal neighbor nodes. The second detection mechanism is based on the fact that by introducing new links into the network, the adversary increases the number of neighbors of the nodes within its radius. An experimental result shows that the proposed method achieves high network performance.

The current research work in wireless sensor networks has mostly focused on the resolving issues related to power consumption and computational resource constraints in the wireless sensor networks .To achieve the same various specific routing schemes ,MAC and cross layered protocols and techniques have been proposed and designed .But with recent advances the privacy issues related to the data collected and transmitted by the wireless sensor networks had taken the center stage .Privacy preservation in wireless sensor networks has become more challenging because of the wireless nature of communication in WSN as well as its self organizing architecture. The present paper provides a comparative review of various privacy preserving mechanisms proposed and implemented in wireless sensor networks with respect to the privacy notions of k- anonymity and L-diversity. Along with the discussion and analysis the present work is an effort for the pavement of a way towards the future research in the field of privacy preservation in WSN.

Mobility in wireless sensor networks poses unique challenges to the Medium Access Control (MAC) protocol design. Previous MAC protocols for sensor networks assume static sensor nodes and focus on energy-efficiency. In this paper, we present MMAC, a mobility-adaptive, collision-free MAC protocol for mobile sensor networks. MMAC caters for both weak mobility (e.g. topology changes, node joins and node failures) and strong mobility (e.g. concurrent node joins and failures, and physical mobility of nodes). When using MMAC, nodes are allowed to transmit at particular time-slots, based on the traffic information and mobility pattern of the nodes. Allowing transmission at particular time-slots makes MMAC a scheduling-based protocol, thereby guaranteeing collision avoidance. Simulation results indicate that the performance of MMAC is equivalent to that of TRAMA in static sensor network environments. In sensor networks with mobile nodes or high network dynamics, MMAC outperforms existing MAC protocols, including TRAMA and S-MAC, in terms of energy-efficiency, delay and packet delivery.

Wireless sensor networks (WSNs) are wireless ad hoc networks of tiny sensor nodes increasingly deployed for multiple civilian and military applications, including patient monitoring, wildlife monitoring, battlefield surveillance, enemy tracking, etc. Like other computer networks, WSNs must be provided of security services such as key management, confidentiality, integrity and authentication. However, the nature of WSNs and their operational requirements introduce new exciting challenges on security design. Key management is a fundamental security service and a hot topic of research in security for WSNs. In this paper, we will review the state of the art on key management for WSNs and provide a glimpse on current and future developments in this area.

Wireless sensor networks (WSNs) are emerging rapidly as a new generation of sensor networks. Despite intensive research in wireless sensor networks (WSNs), limited work has been found in the open literature in the field of WSNs. In particular, quality-of-service (QoS) management in WSNs remains an important issue yet to be investigated. As an attempt in this direction, this paper develops a logic for QoS management (LFQMS) scheme for WSNs with constrained resources and in dynamic and unpredictable environments. Taking advantage of the feedback control technology, this scheme deals with the impact of unpredictable changes in traffic load on the QoS of WSNs. It utilizes a logic controller inside each source sensor node to adapt sampling period to the deadline miss ratio associated with data transmission from the sensor to the sensor. The deadline miss ratio is maintained at a pre-determined desired level so that the required QoS can be achieved. The (LFQMS) has the advantages of generality, scalability, and simplicity. Simulation results show that the (LFQMS) can provide WSNs with QoS support.

Many energy-efficient asynchronous duty-cycle media access control (MAC) protocols for wireless sensor networks (WSNs) have been proposed in recent years. However, for burst traffic, most of them suffer from significant performance degradation due to randomly waking up to communicate with each other. In this paper, we propose a new asynchronous duty-cycle receiver-initiated MAC protocol called HKMAC. In proposed HKMAC, by adaptively adjusting beacon time of the receiver and scheduling the sender's listening time during scheduled period, it can achieve low end-to-end packet delivery latency and high energy efficiency under burst traffic. We have evaluated the performance of HKMAC through detailed ns-2 simulation. The simulation results show that HKMAC can always reduce end-to-end packet delivery latency and energy consumption under various data rates in different topologies compared with RI-MAC - a state-of-the-art MAC protocol in WSNs.