D. Arivudainambi

Energy Efficient Sensor Scheduling for Target Coverage in Wireless Sensor Network

Wireless Sensor Network (WSN) has many successful applications like forest fire detection, military area protection, and so on. Sensors need to be in active mode up to the completion of the task or as long as possible. One method to increase the lifetime of sensor network is by reducing the sensing range of each sensor as required and partitioning these sensors into subsets of sensor covers such that each sensor cover can cover entire targets. Activating these sensor covers one after another will maximize the lifetime of sensor network. Identifying maximum number of sensor covers is modeled as Sensor Cover with Adjustable Sensing Range (SC-ASR). Memetic algorithm is proposed to identify the maximum number of sensor covers with adjustable sensing ranges. Simulation results on various test problems confirm that memetic algorithm significantly outperforms to maximize the network lifetime.

Improved memetic algorithm for energy efficient target coverage in wireless sensor networks

A critical aspect of applications in wireless sensor network (WSN) is its lifetime. This issue has received increased attention due to the recent advances in affordable and efficient integrated electronic devices. One approach to extend the wireless sensor network lifetime is to divide the deployed set of all sensors into disjoint subsets of sensor covers, such that each sensor cover can cover all targets and get activated one after another. The sensor network lifetime can be increased by identifying the maximum number of covers and it can be identified through disjoint set cover (DSC). In this paper, a novel improved memetic algorithm (iMA) is proposed to give a better solution to the DSC. The simulation results on various problem instances confirm that improved memetic algorithm significantly outperforms several heuristic and evolutionary algorithms in terms of solution quality, which demonstrates the effectiveness of the proposed algorithm in extending WSN lifetime.

Analysis of a service facility with cross trained servers and optional feedback

This paper studies a problem faced by a service facility with front and back room operations. The servers in the front room deal with serving customers, perhaps from a queue and those in the back room serve a job which is generated by the front room. In this flexible environment, the problem is to determine the allocation of fixed number of servers between the two rooms depending on the state of the system. The contribution of this paper is to consider the effect of unsatisfied customers that reenter the system. For this purpose, two models are proposed. The main objective of this paper is to minimise the mean number of customer waiting in the queue subject to the back room constraint and both the models are solved using linear programming. A numerical study is conducted to analyse the impact of various parameters on the performance of servers.

A domain specific heuristic algorithm for broadcast scheduling problem in wireless multihop networks

Broadcast scheduling problem in wireless multihop network is to avoid interference while keeping the frame length to a minimum. In addition, the task is determination of a collision free broadcast schedule with the minimum length TDMA frame and the maximum slot utilization by efficient distribution of slots among stations. To solve the problem more effectively, a new domain specific heuristic algorithm called Memetic Algorithm (MA) is proposed in this paper. The results of computation demonstrate that it improves the search capability and the optimum conflict free transmission schedule is obtained with less number of time slots and generations, compared to other competitive algorithms.

Solving Integer Programming Problems with a Variable Number of Switching Costs, Balking and Feedback

We consider a retail service facility with cross trained servers who can perform operations in both front room and back room depending on the length of the queue. Two essential models for service facility are discussed in this paper. The models are represented as a Markovian decision problem and solved using mixed integer programming techniques. Exact solution procedures are developed to solve the models and numerical study is conducted to see the impact of various parameters on performance.

Broadcast scheduling problem for TDMA ad-hoc networks

A domain specific memetic algorithm is proposed for solving the optimum time division multiple access broadcast scheduling problem in Ad-hoc networks. During disaster relief, broadcast scheduling problem in Ad-hoc network is deployed efficiently. The aim is to increase the total number of transmissions in optimized time slot with high channel utilization in a less computation time. The results were compared with other algorithms for broadcast scheduling problem.

Enhancing Quality of Coverage for Target Coverage Problem Using Discrete Haar Wavelet

Quality of coverage is one of the fundamental issues in wireless sensor networks, particularly for the deterministic placement of sensors. One of the methods to improve the quality of coverage is to place the minimum number of sensors in the optimal position to cover the entire target. This paper proposes a discrete Haar wavelet transform for deterministic sensor placement in the target coverage problem. Dilation and translation of Haar wavelet transform are used for identifying the optimal position of sensors. Simulation results validate the performance of discrete Haar wavelet transform better than random placement in terms of optimal placement, quality of coverage and network traffic reduction.

Election of Guard Nodes to Detect Stealthy Attack in MANET

MANETs are exploited due to their dynamic formation of wireless networks and functioning without the help of any infrastructure, thus making them subjected to security attacks. Here we deal with the stealthy attack, wherein the packets sent from the source are disrupted from reaching the destination due to the malicious behavior of any intermediate node. It is a suite of packet misrouting, power control, colluding collision, and identity delegation. The stealthy attack is detected using guard nodes which monitor all its neighboring nodes and formally send a behavior report of its observation. Since the number of neighboring nodes can be high, which could lead to more congestion in exchanging reports, we propose a novel algorithm called DSMG to optimize the selection of the guard nodes, which are empowered with local monitoring. Guard nodes are selected from the common neighbor list of communicating mobile nodes. The selection is further optimized by choosing the node that is more trustworthy. Simulation results show that the overall throughput is increased and also the packet delivery ratio of the nodes in the network is improved.

Hystertic optimal policy of servers in front room and back room with switching time and switching cost

Many retail service are concerned with queueing theory problems, particularly ones which involve optimization. When a worker is being switched from one room to another, he has to move. In some cases this distance is very small, so it can be neglected. In the front room, workers serve customers who may be delayed in a queue. When the back room is interruptible, allowing a worker in the back room to switch to front room work with little delay or lost productivity. To optimize the operations of service facilities, we consider the amount of time that the workers are losing during the switch between the different types of work. After the completion of front room service if the customer is dissatisfied with its service for certain reason or if it received unsuccessful service, the customer may immediately join the second optional service and may leave the queue. The model is derived for switching from the front room to the back room, back room to the front room and loss of productivity due to switches between the rooms as switching cost. Our aim is to minimize customer waiting time with respect to switching servers from the front room to the back room.

Cross trained workers with switching points, switching cost and optional feedback

In this paper a service facility with the front room and the back room has limited number of servers. Two models are analysed. In the first model, given the number of available workers, we determine an optimal policy so that the expected number of customers in queue is minimized subject to a constraint ensuring that there is a sufficient work force to fulfil the functions in the back room. In the second model, the number of workers needed is minimized subject to a additional constraint requiring that the expected number of customers waiting in queue is bounded above by a given threshold value. After the completion of front room service if the customer is unsatisfied with its service for certain reason or if it received unsuccessful service, the customer may immediately join the second optional service and may leave the queue. Exact solution procedures are developed for both models.