Won-Kee Hong

An Effective Data Dissemination in Vehicular Ad-Hoc Network

Vehicular ad-hoc network (VANET) has several characteristics that are different from mobile ad-hoc network (MANET). Due to these characteristics, the network topology based protocol, often used in MANET, can not be applied to VANET. In this paper, we propose an emergency warning message (EWM) broadcast protocol using range-based relay node selecting algorithm, which determines the minimal waiting time spent by a given node before re-broadcasting the received warning message. Because the waiting time for a message transmission is randomly calculated based on the distance between the sender node and the receiver node, the chosen node as the relay node will have have a minimal waiting time. The results of experiment show the proposed algorithm performed better than the flooding and the distance-based relay nodes selecting algorithm in terms of the network load and the end-to-end delay time. Furthermore, the proposed algorithm can reduce message transmission latency under the circumstances of low node density and short transmission range in VANET.

Performance analysis of tag anti-collision algorithms for RFID systems

Lately, the ISO fixed on UHF Gen2 as one of the standard protocols for RFID, called ISO 18000-6 C, along with ISO 18000-6 A/B. It means that the RFID system should provide the multi-protocol support for tag identification and a proper protocol should be chosen depending on the situation. The tag anti-collision algorithm is one of the important research issues to be on top of the protocol’s performance. This paper introduces several anti-collision algorithms for tag identification in the literature and presents the performance comparison and evaluation of those algorithms based on the 96-bit EPCTM (Electronic Product CodeTM). The performance results show that the collision tracking tree algorithm is found to have the highest performance than any other anti-collision algorithm, identifying 749 tags per second.

An effective multi-hop broadcast in vehicular ad-hoc network

Multi-hop broadcast protocols in vehicular ad-hoc network (VANET) require more prompt message dissemination than traditional broadcast protocols because they mainly deal with vital data involved in driver safety. In this paper, a time reservation-based relay node selection algorithm is proposed in order to achieve immediate message dissemination. All nodes in the communication range of a relay node randomly choose their waiting time within a given time-window. The time-window range is determined by a distance from a previous relay node and a reservation ratio of the time-window. A node with the shortest waiting time is selected as a new relay node. The experimental results show that the proposed algorithm has a shorter end-to-end delay time than the distance-based relay node selection algorithm no matter how node density varies. In particular, when the node density is low, the proposed algorithm has a 25.7% shorter end-to-end time and a 46% better performance in terms of the compound metric than the distance-based relay node selection algorithm.

Design and evaluation of in-vehicle sensor network for Web based control

In the ubiquitous computing environment, it is expected that an intellectual vehicle with a capability of intelligence and communication has access to network and get useful information providing service. This requires a new network architecture and in-vehicle sensor network technology to support mobility of vehicle service. The mobility of vehicle service is to give users the vehicle services at any time and any where. In this paper, CDMA-based network architecture is designed for intelligent vehicle services of remote vehicle diagnosis and management. The intelligent vehicle is equipped with a vehicle gateway and in-vehicle sensor network. The performance of the proposed network structure in terms of the round trip time taken to get a vehicle service is evaluated. The experimental results show that the round trip time is appeared to be different when a vehicle is driven or not and where it is driven. It is 776ms when a vehicle is stopped, 707ms when a vehicle is driven in the rural area, and 910ms in the urban area

Experimental research testbeds for large-scale WSNs: a survey from the architectural perspective

Wireless sensor networks (WSNs) have a significant potential in diverse applications. In contrast to WSNs in a small-scale setting, the real-world adoption of large-scale WSNs is quite slow particularly due to the lack of robustness of protocols at all levels. Upon the demanding need for their experimental verification and evaluation, researchers have developed numerous WSN testbeds. While each individual WSN testbed contributes to the progress with its own unique innovation, still a missing element is an analysis on the overall system architecture and methodologies that can lead to systematic advances. This paper seeks to provide a framework to reason about the evolving WSN testbeds from the architectural perspective. We define three core requirements for WSN testbeds, which are scalability, flexibility, and efficiency. Then, we establish a taxonomy of WSN testbeds that represents the architectural design space by a hierarchy of design domains and associated design approaches. Through a comprehensive literature survey of existing prominent WSN testbeds, we examine their best practices for each design approach in our taxonomy. Finally, we qualitatively evaluate WSN testbeds for their responsiveness to the aforementioned core requirements by assessing the influence by each design approach on the core requirements and suggest future directions of research.

WSN-based intelligent telematics system

With the wireless communication network and location data, the existing telematics system provides various information services such as navigation, emergency service, and etc. In addition, it collects and exploits vehicle status through in-vehicle sensor network such as CAN and LIN (Kim et al., 2005). In this paper, WSN-based intelligent telematics system is presented that connects the telematics system and sensor network within the vehicle to the wireless sensor network (WSN) constructed on the road. It provides vehicles with the more intelligent real time services such as environment information on the road, car accident alarm and etc

Internet-Based Human-Vehicle Interface for Ubiquitous Telematics

In the ubiquitous computing environment, a ubiquitous vehicle will be a communication node in the vehicular network as well as the means of ground transportation. It will make humans and vehicles seamlessly and remotely connected. Especially, one of the prominent services in the ubiquitous vehicle is the vehicle teleoperation. However, mutual-collaboration with the in-vehicle communication network, the vehicle-to-vehicle communication network and the vehicle-to-roadside commun- ication network is required to provide vehicle teleoperation services. In this paper, an Internet-based human-vehicle interfaces and a network architecture is presented to provide remote vehicle control and diagnosis services.

DILSA: distributed in-door location system architecture

One of the major issues in the in-door location system is the exact transfer of location data to a mobile node that pursues its current location. The GPS, which is a popular location finding tool in out-door environment, can not be used in in-door environment. Besides, lots of environmental restrictions exists in the indoor other than in the out-door. In this paper, DILSA (distributed in-door location system architecture) is presented to provide accurate location finding in the in-door environment. DILSA uses a sequential routing algorithm. The algorithm is proposed to prevent a mobile node from receiving unnecessary location data from beacon nodes. A mobile node finds out the nearest beacon node by calculating the TDoA (time difference of arrival) between RF and ultrasonic wave to improve the location accuracy. The experimental results show that DILSA has a high accuracy of location estimation

GUI Programming Scheme for Low Storage Usage in Lightweight Computing Environment

A small terminal node with compuation and communication capability is a basic building block for IoT. It is deployed on every objects with sensors and low power wireless communication features and interacts with human as well as other physical or virtual objects. As such, it transmits collected information for IoT to provide intellectual services. Although the progress has been made consistently in sensor technology, human’s intermediate intervention is still required in the industries or the facilities critical for vigilance, security and inspection. Thus, a GUI support in terminal node is needed to make a correct and instant interaction with human. Because of the lightweight computing environment where the terminal node has very small size of storage as well as low performance in computation and communication, the trite GUI programming scheme that makes high computation and memory requirement is inapplicable to the terminal node. In this paper, two image data structures are presented to minimize space requirement of storage for character fonts. They do not reduce the storage requirement for fonts but also decrease communication traffic over the low power and lossy network.

Noise Reduction Scheme for Precise Indoor Localization

The indoor localization is very useful and essential technique in several application area of the wireless sensor network. Various noises such as clock offset, clock drift, and other environmental noises are a hindrance to the accurate localization measurement of a mobile node. In this paper, a new indoor localization scheme is introduced that takes the Kalman Filter to reduce the noises and meausre distances between nodes accurately.The experimental results show that the proposed method improves the accuracy of distance measurement by 18%.