Current Issue : October - December Volume : 2013 Issue Number : 4 Articles : 5 Articles
Clustering provides an effective way to extend the lifetime and improve the energy efficiency of wireless sensor networks (WSNs).\r\nHowever, the cluster heads will deplete energy faster than cluster members due to the additional tasks of information collection\r\nand transmission. The cluster head rotation among sensors is adopted to solve this problem. Cluster head rotation strategies can\r\nbe generally divided into two categories: time-driven strategy and energy-driven strategy. The time-driven strategy can balance\r\nenergy consumption better, but it is not suitable for heterogonous WSNs. The energy-driven cluster head rotation strategy has\r\nhigh energy efficiency, especially in heterogonous networks. However, the rotation will become increasingly frequent with the\r\nreduction of the nodes residual energy for this strategy, which causes lots of energy waste. In this paper, we propose a hybrid cluster\r\nhead rotation strategy which combines the advantages of both energy-driven and time-driven cluster head rotation strategies. In\r\nour hybrid rotation strategy, the time-driven strategy or energy-driven strategy will be selected according to the residual energy.\r\nSimulations show that the hybrid strategy can enhance the energy efficiency and prolong network lifetime in both homogeneous\r\nand heterogeneous networks, compared with either single time-driven or energy-driven cluster head rotation method....
Localization, which determines the geographical locations of sensors, is a crucial issue in wireless sensor networks. In this paper, we\r\npropose a novel lightweight equilateral triangle localization algorithm (LETLA) that accurately localizes sensors and minimizes the\r\npower consumption. In the LETLA, the approximate coordinates substituted for the real coordinates of the unknown node, and the\r\ncorresponding optimization problem is formulated to minimize the estimation error.With the sequences that represent the ranking\r\nof distances from the anchors to the unknown node, a simple and robust technique is developed to quickly and efficiently estimate\r\na region containing the approximate coordinates, and a condition under which the approximate error can be minimized is given.\r\nThis condition employs a newgeometric construct of anchor layout called equilateral triangle diagrams. Extensive simulations show\r\nthat the LETLA performs better than other state-of-the-art approaches in terms of energy consumption with the same localization\r\nprecision....
As an important application domain of wireless sensor networks (WSN), wireless home sensor network (WHSN) can be built\r\nas a traditional WSN. However, when we consider its own character that plug-in sensors are ??xed with AC power supply while\r\nmobile sensors are battery powered, traditional WSN techniques do not match well. In this paper, we propose a smart wireless\r\nhome sensor network architecture with improved routing protocols. It is a hierarchical architecture in which AC-powered sensors\r\nact as backbone nodes for data retransmission, while battery-powered sensors act as leaves that only transmit data relevant to\r\nthemselves. Each sensor is assigned with a prime number as its location identi??er. For our routing algorithm, the LID is used as\r\nrouting address and is decomposed to a sequence of prime numbers that indicates the route towards its destination. In addition, we\r\nimprove existing routing algorithms such as SPIN, LEACH, and DD to incorporate traditional WSN routing algorithms into our\r\nsmart WHSN architecture, and comparable efficiencies are made between them. Moreover, we propose a network path recovery\r\nalgorithm for failures that are caused by node mobility or backbone node failures. All our algorithms have been provided with\r\nfaithful simulations to verify the feasibility and efficiency....
Because of the maturation of wireless technologies, the wireless sensor network has been used in various applications, especially in\r\nthe environmentalmonitoring. After the nodes are deployed on the surveillance field, nodes will die due to the limited energy of the\r\nnode or accidental events, inducing the coverage holes and the break of the transference path. To tackle this problem, researchers\r\nhad proposed the rebuild network topology, such as adding Relay nodes. However, it costs a lot to build such a system. Therefore,\r\nin this paper, we would like to propose anothermethod to tackle the dying nodes as well as the cost. Specifically, we propose a holes\r\nhealing scheme. In order to check its feasibility, we use the analysis of mathematics to acquire the value of the parameters for the\r\nholes healing scheme. With the parameters, we could use the simulated result to prove the effectiveness of the scheme. The result\r\nshows that with the appropriate parameters we could confirm and extend the lifetime ofWSN to infinity....
This paper presents a design and analyzes the performance of an actuator operation scheduler for wireless sensor and actuator networks, aiming at efficiently managing power consumption and distributing peak load in smart grid buildings. To create a schedule within an acceptable response time, a genetic algorithm is designed, and the scheduler places the operations of activated tasks to appropriate time slots in the allocation table. For genetic operations, each schedule is encoded to an integer-valued vector, where each element represents either start time or binary allocation map of the associated task according to the task type. The fitness function evaluates the schedule quality by estimating the load of the peaking slot. Out-task model defines P-Penalty and N-Penalty to account for the extrapower load brought by the delayed start of task operation. The performance measurement results obtained from a prototype implementation reveal that our genetic scheduler reduces the peak load by up to 35.2% for the given parameter set compared with the Earliest scheduling scheme, intelligently compromising two conflicting requirements of even load distribution and small initiation delay....
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