HahnEarl Jeon

Network management framework and lifetime evaluation method for wireless sensor networks

Network Management is the process of managing, monitoring, and controlling the network. Conventional network management was based on wired network which is heavy and unsuitable for resource constrained Wireless Sensor Networks WSNs. WSNs can be large scale networks and it is impossible to manage each node individually. Also, the polling mechanism of Simple Network Management Protocol SNMP imposes heavy management traffic overhead. Since management messages consume resources of WSNs, it can affect the performance of the network. Therefore, it is necessary for WSNs to perform energy efficient network management. Moreover, the management of WSNs should support sustainability. In this paper, we propose a network management framework for WSNs to reduce management traffic. Based on the cluster-based network management architecture, we classify the Management Information Base MIB and define the management messages and message exchange operation for each kind of MIB. The analysis result indicates that the proposed framework can reduce management traffic compared to the polling mechanism and there exists an optimal number of clusters for a given number of nodes. We also propose a lifetime estimation method as an application of the proposed framework. The proposed method uses messages of the proposed framework and estimate the network lifetime from the received management information. Simulation result shows that the proposed method can evaluate the network lifetime and reduce the number exchanged message by using the cluster-based architecture.

Mobility-Adaptive Routing Update Scheme for Wireless Networks with Group Mobility

Wireless mesh network (WMN) has recently emerged as a promising technology for tactical operation. If a platoon is organized with MPs, this system is suitable for tactical coverage is given for battle field where there is a shortage of wired infrastructure. However, MPs of typical WMN are generally fixed. This condition does not apply to diverse tactical scenarios. In this paper, it is considered that MPs have group mobility for flexible tactical networks. We propose cluster based multi-channel MAC scheme for mobilie WMN with single antenna condition. We have reduced the collision problems and message storming problems occur by mobility, so the reliability of WMN has been improved. Consequently, reliable communication is guaranteed by our framework in mobile WMN.

A Scalable MAC Protocol Supporting Simple Multimedia Traffic QoS in WSNs

Wireless sensor networks (WSNs) are a vibrant research field for the last several years. Especially, design of MAC protocols supporting multimedia traffic QoS is recent challenging work. However, the mechanisms of protocols that can guarantee multimedia traffic QoS have several problems in multihop wireless sensor networks. There are a lot of reasons, including limited end-to-end delay and high throughput. In this paper, we propose ascalable MAC protocol that guarantees multimedia traffic, still images, and scalar sensor data QoS in multi-hop wireless sensor networks. The MAC protocol has made it possible to transmit multimedia streaming traffic without a great change of the end-to-end delay for a specific time. And if there are the some link failures in multi-hop transmission, the protocol can recover the links quickly. Using this algorithm, the proposed MAC protocol outperforms the IEEE 802.11e EDCF and the IEEE 802.15.4 MAC protocol in terms of the end-to-end delay and stable transmission of multimedia streaming data.

Network Management Framework for Wireless Sensor Networks

Network Management is the process of managing, monitoring, and controlling the network. Conventional network management was based on wired network which is heavy and unsuitable for resource constrained WSNs. WSNs can have large scale network and it is impossible to manage each node individually. Also, polling mechanism of Simple Network Management Protocol (SNMP) impose heavy management traffic overhead. Since management messages consume resources of WSNs, it can affect the performance of the network. Therefore, it is necessary for WSNs to perform energy efficient network management. In this paper, we will propose network management framework. We will introduce cluster-based network management architecture, and classify the Management Information Base (MIB) according to their characteristics. Then, we will define management messages and message exchange operation for each kind of MIB. The analysis result of the management overhead indicates that the proposed framework can reduce management traffic compared to polling mechanism.

The effect of spreading gain control on a CDMA slotted ALOHA system

In a CDMA slotted ALOHA channel, the bit rate of user information is determined by a spreading gain. The large value of spreading gain enhances the packet throughput by increasing the probability of a successful packet transmission. However, it degrades the effective throughput by reducing the number of information bits carried via a packet. To solve the problem, we investigated the effect of spreading gain control (SGC) on both throughputs, and evaluated the throughput performance for various SGC schemes. The results show that variable SGC achieves considerably higher effective throughput by adjusting the value of spreading gain to interference level.

Performance analysis of QoS routing with network dependant delay cost

This paper investigates the problem of path calculation of multiple metric routing. Todays Internet routing is based on a single metric path selecting algorithm. The single metric path is a best effort service that can only support a path for one requirement. In order to support quality-of-service (QoS) call, the path is subject to multiple constraints on the routing metric. In many cases, the path finding problem is NP-complete. This paper proposes the widest-least cost routing algorithm that uses a cost metric that is based on a delay metric and influenced by the resource bandwidth metric and network state. This algorithm is a multiple metric routing algorithm that has the traffic distribution ability to serve a traffic engine ring. Our goal is to select the shortest path when the network link is not loaded, and perform traffic engineering to move traffic to the other path when the network load is heavy. We have studied the performance through simulation and compared it against other routing algorithms.

Topology Control Method Using Adaptive Redundant Transmission Range in Mobile Wireless Sensor Network

In this paper, we simulate the effect of RTR (Redundant Transmission Range) which is used to maintain network connectivity in mobile wireless networks such as ad-hoc or sensor networks. The simulation result shows that the RTR scheme greatly increases network connectivity time. Based on the simulation result, we propose an A-RTR (Adaptive-RTR) algorithm. A-RTR use variable RTR as node’s moving speed and neighbors’ speed. This algorithm can be used any topology control algorithms and prolong the network connectivity time in mobility environment. Simulation results show good performance not only the network connectivity but also node’s energy consumption.