Hee Yong Youn

Energy Efficient Routing Protocols for Mobile Ad Hoc Networks

Summary Although establishing correct and efficient routes is an important design issue in mobile ad hoc networks (MANETs), a more challenging goal is to provide energy efficient routes because mobile nodes’ operation time is the most critical limiting factor. This article surveys and classifies the energy-aware routing protocols proposed for MANETs. They minimize either the active communication energy required to transmit or receive packets or the inactive energy consumed when a mobile node stays idle but listens to the wireless medium for any possible communication requests from other nodes. Transmission power control approach and load distribution approach belong to the former category, and sleep/power-down mode approach belongs to the latter category. While it is not clear whether any particular algorithm or a class of algorithms is the best for all scenarios, each protocol has definite advantages/disadvantages and is well suited for certain situations. The purpose of this paper is to facilitate the research efforts in combining the existing solutions to offer a more energy efficient routing mechanism. Copyright # 2003 John Wiley & Sons, Ltd.

Performance analysis of finite buffered multistage interconnection networks

The authors present a model which can accurately evaluate the performance of single-buffered and multibuffered MINs (multistage interconnection networks) with 2*2 switching elements (SESs). Earlier models were inaccurate because of the simplicity, or hard to expand for larger SEs or buffer sizes due to their complexity. The proposed model for single-buffered MINs has only three states, including the blocked state, while it is very accurate by realistically modeling the transactions between buffers in adjacent stages and network cycles. The model was expanded for multibuffered MIN, and it was found to be still very accurate. Comparisons with simulation and the YLL model (see H.Y. Yoon et al., 1990) revealed that the proposed models are consistently much more accurate irrespective of the size of the network, buffer, and traffic condition. The proposed model can be easily expanded for any other structures and operation conditions of MINs.<<ETX>>

An efficient task allocation scheme for 2D mesh architectures

Efficient allocation of processors to incoming tasks in parallel computer systems is very important for achieving the desired high performance. It requires recognizing the free available processors with minimum overhead. In this paper, we present an efficient task allocation scheme for 2D mesh architectures. By employing a new approach for searching the mesh, our scheme can find the available submesh without scanning the entire mesh, unlike earlier designs. Comprehensive computer simulation reveals that the average allocation time and waiting delay are much smaller than earlier schemes of comparable performances, irrespective of the size of meshes and distribution of the shape of the incoming tasks.

Energy-Driven adaptive clustering hierarchy (EDACH) for wireless sensor networks

Wireless sensor network consists of small battery powered sensors. Therefore, energy consumption is an important issue and several schemes have been proposed to improve the lifetime of the network. In this paper we propose a new approach called energy-driven adaptive clustering hierarchy (EDACH), which evenly distributes the energy dissipation among the sensor nodes to maximize the network lifetime. This is achieved by using proxy node replacing the cluster-head of low battery power and forming more clusters in the region relatively far from the base station. Comparison with the existing schemes such as LEACH (Low-Energy Adaptive Clustering Hierarchy) and PEACH (Proxy-Enabled Adaptive Clustering Hierarchy) reveals that the proposed EDACH approach significantly improves the network lifetime.

Mobile RFID Tag Detection Influence Factors and Prediction of Tag Detectability

Radio-frequency identification (RFID) readers are powered RF devices that communicate with tags (whether mobile or fixed) and read necessary information to be processed. A mobile RFID tag is detected by an RFID antenna. In a mobile RFID where the RFID tag is attached to a mobile object such as a vehicle, a human, or an animal, information is more difficult to detect than in the case where the tag is attached to a stationary object. Currently, deployment engineers and researchers use trial-and-error approaches to decide on the best conditions of the tag detection influence factors which affect tag detectability (detection rate). As expected, these approaches are time consuming. Even though mobile RFID systems have become widely used in industry and tag detection problems are crucial at deployment, very few researches on them have been conducted so far. Thus, a quick and simple method for finding tag detectability is needed to improve the traditional time consuming trial-and-error method. In this paper, we propose a unique approach ldquothe intelligent prediction method of tag detection rate using support vector machine (SVM).rdquo The intelligent method predicts the mobile RFID tag detectability instead of the trial-and-error experimental procedures. The simulation results of the proposed method are very comparable to the trial-and-error experimental approach. The proposed intelligent method gives a very high accuracy of mobile RFID tag detectability prediction and proves to be superior to the current method in time as well cost savings. The predicted tag detectability results can be used for analyzing mobile RFID tag detection influence factors and their conditions.

A Novel Cluster Head Selection Method based on K-Means Algorithm for Energy Efficient Wireless Sensor Network

Wireless sensor network consists of hundreds to thousands of sensor nodes gathering various data including temperature, sound, location, etc. They have been applied to numerous fields such as healthcare, monitoring system, military, and so forth. It is usually difficult to recharge or replace the sensor nodes which have limited battery capacity. Energy efficiency is thus a primary issue in maintaining the network. In this paper we propose an efficient cluster head selection method using K-means algorithm to maximize the energy efficiency of wireless sensor network. It is based on the concept of finding the cluster head minimizing the sum of Euclidean distances between the head and member nodes. Computer simulation shows that the proposed approach allows better performance than the existing hierarchical routing protocols such as LEACH and HEED in terms of network lifetime.

Tree-Based Clustering(TBC) for Energy Efficient Wireless Sensor Networks

Wireless sensor networks are widely used for gathering data in an autonomous fashion. Since sensors are power constrained devices, it is quite important for them to minimize the energy consumption. In this paper we propose a novel tree-based clustering (TBC) approach for energy efficient wireless sensor networks. Here the nodes in a cluster form a tree with the root as the cluster-head, while the height of the tree is decided based on the distance of the member nodes to the cluster-head. Computer simulation shows that the proposed scheme effectively reduces and balances the energy consumption among the nodes, and thus significantly extends the network lifetime compared to the existing schemes such as LEACH, PEGASIS, and TREEPSI.

An Energy Efficient Routing Scheme for Wireless Sensor Networks

Since sensor nodes have limited energy, energy efficient routing is very important for wireless sensor network (WSN). In this paper we propose a routing scheme which significantly enhances the performance of existing schemes such as LEACH and IEACH-C. The proposed scheme selects the cluster head not randomly but considering the remaining energy when the energy level drops below 50% of the initial energy. For each node, the cluster head to join is determined by not only the signal power but also the remaining energy of the cluster head. Also, data transmission occurs when the context satisfies the preset condition. NS-2 simulation shows that the proposed scheme outperforms LEACH and LEACH-C by 37% and 30%, respectively, in terms of the lifetime of the sensor network.

An efficient key pre-distribution scheme for secure distributed sensor networks

Wide-spread deployment of sensor networks is emerging and it presents an economical solution to numerous problems. A number of applications are dependent on secure operation of the sensor network, however, and serious consequences are incurred if the network is compromised or disrupted. In the existing key pre-distribution scheme suitable for low power and resource sensor nodes, shared key is not guaranteed to be found and mutual authentication is not allowed. This paper thus proposes a new key pre-distribution scheme guaranteeing that any pair of nodes can find a common secret key between themselves by using the keys assigned by LU decomposition of a symmetric matrix of a pool of keys. Furthermore, it allows node-to-node mutual authentication. Analysis shows that the existing scheme requires a large number of keys in each sensor node to display a comparable performance as the proposed scheme. Therefore, the superiority of the proposed scheme is more substantial when the memory size of the sensor node is small.

CALM: an intelligent agent-based middleware for community computing

The applications for ubiquitous system require to effectively use the resources distributed in the environment for providing customized services to the users. In this paper we propose a middleware architecture displaying high scalability with event-based multi-agent platform, which allows dynamic creation of community for service oriented computing. It consists of event-based communication platform implemented by extending omniORB, agent platform, and various frameworks. The effectiveness of the proposed architecture is demonstrated using a ubiquitous office service scenario