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Network lifetime aware area coverage for clustered directional sensor networks

The problem of field or area coverage in Directional Sensor Networks (DSNs) presents huge research challenges including appropriate selection of sensors with their active sensing directions in an energy-efficient way. Existing solutions permit to execute coverage enhancement algorithms in each individual sensor nodes, leading to high communication and computation overheads, loss of energy and reduced accuracy. In this paper, we have proposed a novel network lifetime aware area coverage solution, NLAC, for a clustered DSN, where distributed cluster heads (CHs) have the responsibility of determining the number of active member nodes and their sensing directions. The CHs minimizes the overlapping coverage area and energy consumption by switching more nodes in sleep state. The proposed NLAC system is fully distributed and it exploits single-hop neighborhood information only. Results from extensive simulations, show that NLAC system offers better performance in terms of covering area and networklife.

A duty cycle directional MAC protocol for wireless sensor networks

The directional transmission and reception of data packets in sensor networks minimize the interference and thereby increase the network throughput, and thus the Directional Sensor Networks (DSN) are getting popularity. However, the use of directional antenna has introduced new problems in designing the medium access control (MAC) protocol in DSNs including the synchonizaiton of antenna direction of a pair of sender-receiver. In this paper, we have developed a duty cycle MAC protocol for DSNs, namely DCD-MAC, that synchronizes each pair of parent-child nodes and schedules their transmissions in such a way that transmission from child nodes minimizes the collision and the nodes are awake only when they have transmission-reception activities. The proposed DCD-MAC is fully distributed and it exploits only localized information to ensure weighted share of the transmission slots among the child nodes. We perform extensive simulations to study the performances of DCD-MAC and the results show that our protocol outperforms a state-of-the-art directional MAC protocol in terms of throughput and network lifetime.

A Low Duty Cycle MAC Protocol for Directional Wireless Sensor Networks

Directional communication in wireless sensor networks minimizes interference and thereby increases reliability and throughput of the network. Hence, directional wireless sensor networks (DWSNs) are fastly attracting the interests of researchers and industry experts around the globe. However, in DWSNs the conventional medium access control protocols face some new challenges including the synchronization among the nodes, directional hidden terminal and deafness problems, etc. For taking the advantages of spatial reusability and increased coverage from directional communications, a low duty cycle directional Medium Access control protocol for mobility based DWSNs, termed as DCD-MAC, is developed in this paper. To reduce energy consumption due to idle listening, duty cycling is extensively used in WSNs. In DCD-MAC, each pair of parent and child sensor nodes performs synchronization with each other before data communication. The nodes in the network schedule their time of data transmissions in such a way that the number of collisions occurred during transmissions from multiple nodes is minimized. The sensor nodes are kept active only when the nodes need to communicate with each other. The DCD-MAC exploits localized information of mobile nodes in a distributed manner and thus it gives weighted fair access of transmission slots to the nodes. As a final point, we have studied the performance of our proposed protocol through extensive simulations in NS-3 and the results show that the DCD-MAC gives better reliability, throughput, end-to-end delay, network lifetime and overhead comparing to the related directional MAC protocols.

Area coverage for clustered directional sensor networks using Voronoi diagram

Area coverage is a fundamental research problem in Directional Wireless Sensor Networks (DSNs). Unlike omni-directional sensors, it is required to activate the sensor nodes along with their sensing directions in DSNs. Appropriate selection of sensing sectors that can maximize the area coverage is a challenging problem here. In this work, we develop a greedy algorithm for area coverage in clustered DSNs using Voronoi diagram. To improve the overall area coverage ratio in the network, the cluster head activates the directional sensors by considering the area coverage contribution of sensors in the Voronoi cells. The use of clustering and Voronoi cells reduces the computational complexity and increases the overall coverage ratio. The simulation experiement results show the efficacy of the algorithm over the state-of-the-art works it is compared to.

Optimization of Wireless Ad-hoc Networks using an Adjacent Collaborative Directional MAC (ACDM) Protocol

In this paper we designed a modern Medium access control (MAC) protocol for wireless ad-hoc network that focuses on neighbor node information availability and uses directional antenna. MAC protocol coordinates different users to share the wireless channel fairly and resourcefully in the wireless networks. However, using directional antennas in ad-hoc networks causes new challenges such as new hidden terminal, deafness problems, unnecessary blocking of nodes etc. The problems arise mostly due to lack of information of the neighbor node’s activities. Thus, we proposed a new directional MAC protocol name Adjacent Collaborative Directional MAC Protocol (ACDM) for wireless ad-hoc networks. The objective is to improve the throughput and delay performance together with overhead reduction of the wireless network. In addition, the integrity of the ACDM has been verified using the distributed network simulator tool NS3. The simulation results have shown that the ACDM protocol outperforms the existing protocols of wireless networks using directional antennas by minimizing the depressing effect of hidden-terminal, deafness and head of line blocking problems that also avoids asymmetry-in-gain problem. The performance of ACDM protocol shows that it improves the throughput and reduces the overhead from the state-of-art works.

Directional MAC Protocols in Ad-Hoc Networks

In wireless ad-hoc networks, the beam forming antenna technology is a new and promising solution to many challenges. Beam forming antennas have the ability to increase the spatial reuse, improve the transmission reliability, extend the transmission range and/or save the power consumption. If they are effectively used, they can significantly improve the network capacity, lifetime, connectivity and security. However, traditional Medium Access Control (MAC) protocols fail to exploit the potential benefits due to the unique characteristics of wireless ad-hoc networks with beam forming antennas. Ad-hoc networks suffer from the problem of hidden nodes (terminals), which leads to several degradation of network throughput. This survey gives a comprehensive overview of Medium Access Control (MAC) protocols which directly or indirectly address this problem. Open research discussions are also discussed to serve as a starting point for future protocol design and evaluation.

Tradeoff Between Sensing Quality and Network Lifetime for Heterogeneous Target Coverage Using Directional Sensor Nodes

Conventional researches on target coverage in directional sensor networks (DSNs) mainly focus to increase the network lifetime, overlooking the coverage quality of targets, especially they don’t consider the targets that have heterogeneous coverage requirements. Increasing sensing quality is of the utmost importance to ensure comfort living in smart cities. In this paper, we have designed a generalized framework, namely maximizing coverage quality with minimum number of sensors in DSN (MQMS-DSN) that has the ability to maximize the target coverage quality, or the network lifetime, or to make an efficient tradeoff in between the two following application demand. Using a probabilistic model for measuring the sensing coverage quality, we have developed optimal, suboptimal, and greedy solutions for MQMS problem. Empirical evaluations of the proposed MQMS systems have been carried out in network simulator version 3 (ns-3). The results show the effectiveness of the proposed systems compared with the state-of-the-art-works in terms of sensing quality and network lifetime.

α-Overlapping area coverage for clustered directional sensor networks

Area coverage problem in Directional Sensor Networks (DSNs) presents great research challenges including minimization of number of active sensors and overlapping sensing coverage area among them, determination of their active sensing directions in an energy-efficient way, etc. Existing solutions permit to execute coverage enhancement algorithms at each individual sensor nodes, leading to high communication and computation overheads, loss of energy and reduced sensing coverage. In this paper, we first formulate the problem of maximizing area coverage with minimum number of active nodes as a mixed-integer linear programming (MILP) optimization problem for a clustered DSN. Due to its NP-completeness, we then develop a greedy alternate solution, namely α-overlapping area coverage (α-OAC). In α-OAC, each cluster head (CH) takes the responsibility of determining the active member nodes and their sensing directions, where, each sensing node is allowed to have at most α% coverage overlapping with its neighbors. The α-OAC CHs activate a sensor node iif the later has sufficient residual energy and send other member nodes to the sleep state. The proposed α-OAC system is distributed and scalable since it requires single-hop neighborhood information only. Results from extensive simulations, done in NS-3, reveal that the α-OAC system outperforms state-of-the-art works in terms of area coverage, network lifetime and operation overhead.

Starfish Routing for Wireless Sensor Networks with a mobile sink

Wireless sensor networks (WSNs) with a mobile sink have been proven to provide extended network lifetime and better data delivery performances compared to networks with a static sink. This is achieved due to reduction of routing costs and balanced-distribution of energy burden on multiple nodes in the network. In this paper, we have developed Starfish Routing protocol, inspired from water vascular system of Starfish, that constructs a routing backbone with a central ring canal and few radial canals across the network. The number of radial canals and the radius of the ring canal have been jointly determined for a given network so as to reduce the communication latency from sources to the sink. The results of performance evaluation outperform the state-of-the-art works in terms of data delivery delay and network lifetime.

Network lifetime aware coverage quality maximization for heterogeneous targets in DSNs

Conventional researches on target coverage in Directional Sensor Networks (DSNs) mainly focus to increase the network lifetime, overlooking the coverage quality of targets, especially considering the targets that have heterogeneous coverage requirements. In this work, we have developed a sensor scheduling mechanism, MCQ-DSN, that maximizes the coverage quality for different targets while minimizing the active number of sensor devices at a certain time so as to increase the network lifetime. The coverage quality of a target for a sensor device is measured through probabilistic sensing model and nodes having higher residual energy is given priority for scheduling. To verify the performance of our proposed MCQ-DSN system, we have simulated it on Network Simulator version 3 (ns-3), and experimental results show that it outperforms a number of state-of-the-art-works.