Kil-Woong Jang

Meta-heuristic algorithms for channel scheduling problem in wireless sensor networks

The channel scheduling problem is to decide how to commit channels for transmitting data between nodes in wireless networks. This problem is one of the most important problems in wireless sensor networks. In this problem, we aim to obtain a near-optimal solution with the minimal energy consumption within a reasonable time. As the number of nodes increases in the network, however, the amount of calculation for finding the solution would be too high. It can be difficult to obtain an optimal solution in a reasonable execution time because this problem is NP-hard. Therefore, most of the recent studies for such problems seem to focus on heuristic algorithms. In this paper, we propose efficient channel scheduling algorithms to obtain a near-optimal solution on the basis of three meta-heuristic algorithms; the genetic algorithm, the Tabu search, and the simulated annealing. In order to make a search more efficient, we propose some neighborhood generating methods for the proposed algorithms. We evaluate the performance of the proposed algorithms through some experiments in terms of energy consumption and algorithm execution time. The experimental results show that the proposed algorithms are efficient for solving the channel scheduling problem in wireless sensor networks. Copyright

A tabu search algorithm for routing optimization in mobile ad-hoc networks

In this paper, we propose a routing optimization algorithm to efficiently determine an optimal path from a source to a destination in mobile ad-hoc networks. To determine an optimal path for the nodes is important for transmitting data between nodes in densely deployed networks. In order to efficiently transmit data to its destination, the appropriate routing algorithms must be implemented in mobile ad-hoc networks. The proposed algorithm is designed by using a tabu search mechanism that is a representative meta-heuristic algorithm. The proposed tabu search algorithm carries out two neighborhood generating operations in order to determine an optimal path and minimize algorithm execution time. We compare the proposed tabu search algorithm with other meta-heuristic algorithms, which are the genetic algorithm and the simulated annealing, in terms of the routing cost and algorithm execution time. The comparison results show that the proposed tabu search algorithm outperforms the other algorithms and that it is suitable for adapting the routing optimization problem.

Location tracking for wireless sensor networks

In location tracking, there is a trade-off between data accuracy of mobile targets and energy efficiency of sensor nodes. If the number of nodes is increased to track a mobile target, the level of data accuracy increases, but the energy consumption of nodes increases. In this paper, we propose a new location tracking scheme that considers these two factors. The proposed scheme is designed to track mobile targets in a cluster-based sensor network. In order to increase the energy efficiency of sensor nodes, a portion of nodes that detect the mobile target is selected to track the target using the backoff procedure. In addition, we consider data accuracy as controlling the number of nodes by varying the transmission range of the nodes. We perform a simulation to evaluate the performance of the proposed scheme over sensor networks. We provide simulation results comparing the proposed scheme with the general approach. The simulation results show that the proposed scheme has the excellent performance over a broad range of parameters.

A New Backoff Algorithm to Guarantee Quality of Service over IEEE 802.11 Wireless Local Area Networks

In this paper, we propose a new backoff algorithm to guarantee quality of service over IEEE 802.11 wireless local area networks. It is designed to carry out the proposed backoff algorithm, which changes the contention window size for backoff time using information of basic service area, such as number of stations. We evaluate the performance of the proposed algorithm using Markov model analysis and compare it with the IEEE 802.11e backoff algorithm. The numerical results show that the proposed algorithm is able to offer better performance than the conventional backoff algorithm in terms of the throughput.

An Optimization Algorithm for Minimum Energy Broadcast Problem in Wireless Sensor Networks

ABSTRACT The minimum energy broadcast problem is for all deployed nodes to minimize a total transmission energy for performing a broadcast operation in wireless networks. In this paper, we propose a Tabu search algorithm to solve efficiently the minimum energy broadcast problem on the basis of meta-heuristic approach in wireless sensor networks. In order to make a search more efficient, we propose a novel neighborhood generating method and a repair function of the proposed algorithm. We compare the performance of the proposed algorithm with other existing algorithms through some experiments in terms of the total transmission energy of nodes and algorithm computation time. Experimental results show that the proposed algorithm is efficient for the minimum energy broadcast problem in wireless sensor networks. *한국해양대학교 데이터정보학과 네트워크 연구실 (jangkw@hhu.ac.kr) 논문번호：KICS2012-02-044, 접수일자：2012년 2월 2일, 최종논문접수일자：2012년 4월 5일 Ⅰ. 서 론 무선 센서 네트워크는 육상 및 지하 , 해저와 같은 다양한 환경에 센서를 배치하여 인간이 닫기 어려운 지역의 정보를 쉽게 얻도록 도와주는 기능을 한다

Design and Implementation of IEC 61162-4 based TLI Protocol for e-Navigation on Ship

In this paper, we propose a transmission algorithm of the TLI protocol of the IEC 61162-4 standard to perform the e-Navigation on ship, and we design and implement the TLI protocol according to the proposed algorithm. The implemented protocol is a TCP/IP based protocol, and is a network protocol with the MAU and LNA components proposed in the IEC 61162-4 standard. In addition, it makes a data transmission over the network architecture based on client/server network model. In the implemented protocol, there are a communication between the MAU and the LNA in one host, and also a communication between the LNA and the LNA in each other hosts. In order to provide a variety of service in a host, every client host has a LNA and multiple MAUs. According to the standard specification and the proposed transmission algorithm, we designed and implemented the TLI protocol using object-oriented mechanism. We carried out the experiment under a simple network model similar to real ship environment, and confirmed that it successfully transmits and receives data between the hosts.

An adaptive self-organization protocol for wireless sensor networks

This paper proposes a new self-organization protocol for sensors with low-power battery in wireless sensor networks. In our protocol, sensor networks consist of a hierarchical architecture with a sink, which is a root node, using the spanning tree algorithm. Our protocol utilizes some control messages to construct a hierarchical architecture, and by exchanging the messages between nodes, maintains adaptively the network topology by reorganizing the tree architecture as the network evolves. We perform the simulation to evaluate the performance of our protocol over wireless sensor networks. We provide simulation results comparing our protocol with the conventional approaches. The results show that our protocol outperforms other protocols over a broad range of parameters.

A balanced deployment algorithm for mobile sensor networks

This paper describes a grid-based deployment algorithm to maximize the network coverage in mobile sensor networks. The algorithm divides target areas with scattered mobile sensors into some grids and selects a grid header in each grid. The grid header is responsible for collecting the information of nodes in the grid. If the number of nodes in the grid is less than the average number of nodes, the grid header requests the node movement to neighboring grids. After the node movement from the neighboring grids, if the number of nodes in the grid is below the average, it requests the node movement to the two-hop grids apart through the neighboring grids. After the node movement from the two-hop grids, the grid header performs to relocate its members in the grid. By performing three procedures, the algorithm is able to deploy uniformly the given nodes in the target area. This paper presents the operation of a balanced deployment algorithm and shows performance evaluation of the deployment algorithm.

Explicit multicast extension for a large multicast group

For the Explicit Multicast (Xcast) scheme, we propose a scheme that provides dynamic group membership and supports large group members. In the scheme, group receivers can have dynamic group membership and a destination field of the Xcast header has addresses of Xcast-aware routers (XRs) instead of receivers in order to reduce the packet size. Analytical and simulation results show that our, scheme can reduce more Xcast header size and cost in forwarding packets than the Xcast, especially for a large multicast group. Like traditional multicast schemes, our scheme can support large multicast group members.