Misun Yu

REAR: Reliable Energy Aware Routing Protocol for Wireless Sensor Networks

In wireless sensor networks, micro sensor nodes dispersed in real environmental field have a constraint energy capacity, so energy-efficient mechanism for wireless communication on each sensor node is so crucial. Specially, the jobs sending and processing sensing data information from on sensor node to the others are more majority parts than merely sensing some events. Thus, energy-efficient routing protocol in wireless sensor networks is necessary for increasing the network lifetime and is also influenced by many challenging factors in terms of energy, processing, and storage capacities. In this paper, we designed and implemented a reliable energy aware routing (REAR) protocol for wireless sensor networks and evaluated the performance of REAR by comparing with existing routing protocols. REAR considers residual energy capacity of each sensor node in establishing routing paths and supports multi-path routing protocol for reliable data transmission. Furthermore, REAR allows each sensor node to confirm success of data transmission to other sensor nodes by supporting the DATA-ACK oriented packet transmission. Finally, the performance evaluation results show that REAR provides energy-efficiency and reliability related to wireless communication in wireless sensor networks.

DAP: Dynamic Address Assignment Protocol in Mobile Ad-hoc Networks

In general IP networks, addresses can be assigned to hosts manually by a network administrator or automatically by a DHCP server. Mobile ad-hoc network (MANET), which is a self-configuring network, is the union of mobile hosts that form an arbitrary topology. Most research related to the MANET assumes that hosts IP address is configured, prior to the node joining the MANET. However, it is impossible that a network administrator or DHCP server configures host IP addresses in MANETs because there is no infra-structure. For this reason, a dynamic address management protocol is essential in MANETs. Thus, this paper proposes a novel self-configuring address management protocol, referred to as DAP (distributed address pool), in which IP addresses can be dynamically allocated to a newly-joined host in MANETs with no network infra-structure. In DAP, every host in a MANET has a unique IP address pool (a set of unused addresses that will be used for new joined hosts in MANETs) and address assignments are performed locally in the host. The advantage of this method is that it does not generate any broadcasting messages and, in turn, address allocation time can be significantly reduced. From our simulations, DAP showed a superior performance to a random address allocation scheme (RADA) in terms of both address allocation time and message exchange overhead.

RNIndoor: A relay node deployment method for disconnected wireless sensor networks in indoor environments

In a 2D indoor environment, finding the proper location of relay nodes for wireless sensor networks is a difficult and time consuming job because walls, rooms and restricted areas can prevent the placement of nodes. Moreover, the number of relay nodes is an important factor. Too many relay nodes may increase installation cost and communication delays as well as spoil the beauty of the insides of buildings. In this paper, we present a heuristic relay node deployment method for indoor wireless sensor networks (RNIndoor). The method places as few additional relay nodes as possible to provide at least one path among the deployed nodes in a floor using structural information of the floor (indoor environment) and path loss generated from propagation models. The walls and restricted areas are considered in finding the locations of additional relay nodes. Our method can be effectively used in the initial stage of real deployment or a simulator in a wireless sensor network domain to reduce installation time and cost. We compared it with other deployment methods to validate the superiority of our method.

NanoMon: A Flexible Sensor Network Monitoring Software

In this paper, we present a sensor network monitoring software, named NanoMon, which has a highly flexible architecture and is able to support various user requirements arising in their individual wireless sensor network applications in an adaptive manner. With NanoMon, users can specify their own sensor types and custom GUI components by using a simply describable configuration file; and it can be automatically integrated to NanoMon GUI framework to support user-specific sensor network applications. NanoMon employs a widely used database, MySQL, to manage sensing data and node information of several types of sensor network applications and also to provide sensor data history and conditional sensor data look up functions. NanoMon provides well defined packet form at and transmission procedure to communicate with various sensor network platforms with no dependency on any specific WSN platforms; and it can publish sensing data received from sensor networks to other external monitoring devices via Internet using well defined XML packet format and transmission procedure. For platform independency, NanoMon is implemented in Java language.

NanoMon: An Adaptable Sensor Network Monitoring Software

In this paper, we present a sensor network monitoring software, named NanoMon, which has a flexible architecture and supports for various user requirements of sensor network applications in an adaptive manner. With NanoMon, users can specify custom GUI plug-ins and internal module parameters by using a simply describable configuration file; and it can be automatically integrated to NanoMon framework to support user-specific sensor network applications. NanoMon employs a widely used database MySQL, to concurrently and correctly manage sensing data and node information of several types of sensor network applications. To show flexibility and adaptability of NanoMon, we implemented two WSN applications- home monitoring and parking lot monitoring systems. By selecting a WSN application name specified in the configuration file, users can easily and dynamically change GUI and internal module parameters such as sensor types and database locations of NanoMon used to display the status of WSN.

NACA: A New Adaptive CSMA/CA Algorithm of IEEE 802.15.4 in Beacon-enabled Networks

In this paper, we propose a new adaptive CSMA/CA algorithm (NACA) that aims to reduce redundant transmission of IEEE 802.15.4 LR-WPAN. In wireless sensor networks (WSN), energy consumption is one of the most important issues. Furthermore, it makes the network life-time longer by reducing retransmission. To achieve this goal, we improve the carrier sensing features in MAC layer of IEEE 802.15.4. When the network is busy, the MAC detects it and adaptively chooses the parameters of CSMA/CA mechanism to minimize collisions and redundancy of retransmission packet based on the NACA. We evaluated the proposed scheme with original 802.15.4 MAC on the ns-2 simulator. The results show that our scheme outperforms the original by about 15% in case of retransmission.

RealSSim: a simulator for indoor sensor network systems

Existing sensor network simulators are not appropriate for indoor sensor network systems. We present RealSSim, the sensor network simulator especially developed for indoor sensor networks. RealSSim considers the structure of buildings and the quality of construction materials for accurate radio propagation analysis. It also supports an attractive visualization of the level as commercial products. In our demonstration, we show the whole process of simulation for two indoor sensor network systems.

Multimedia data generation algorithm for multi-user video conferencing system over ad-hoc networks

In this paper, a multimedia data generation algorithm for multi-user video conferencing system over ad-hoc networks is proposed. In the proposed method, the scene-changed frame is estimated using the number of bits pre-encoded by the hardware accelerator and the percentage of the intra-coded macroblocks in each frame. The resulting scene-changed frames are re-encoded as the intra-coded frames and then transmitted to the receiver. Compared to the bit-stream generated from encoding the entire sequence, the proposed algorithm achieves up to about 50% reduction of the bit-rate without skipping the key frames while maintaining the perceptual video quality.

A Design and Implementation of Wireless Sensor Network Security on Nano-Qplus Platform

The sensor network features characteristics such as nodes being densely distributed, large quantities of nodes being scattered around, necessity of frequently changing the network topology as well as utilizing broadcasting system for communication. It also reflects a wireless network environment where batteries and computing powers are limited that it would be difficult to even make a decision on whether surrounding nodes are in credible conditions. Not only the numbers of nodes through which sensor nodes communicate exceed one, but additional research on password key control is required. It would be used on mutual authentication between nodes as well as authentication and enciphering by using limited sensor resources within the sensor network, which is based on the mesh structure. This paper makes statements on encryption algorithm, key management, security protocol, authentication and essential security elements of secure routing. It will be acting as basis of developing security mechanism, which will provide confidentiality of the MAC class level, authentication and integrity on a sensor network environment referred as the nano-Qplus platform.