This paper presents a packet-relay method of receiving sensor data of long-distance nodes with predefined bit-rate sensing. The proposed method is an enhancement of the IEEE802.15.4 standard in order to provide reliable and robust wireless sensor communications even when radio propagation environment is not sufficiently good. Elaborate field tests show that… (More)
In this paper, we will introduce the relay system based on time division duplexing technology. Especially, we suggest various frame structure to adjust the throughput ratio of downlink and uplink. Finally, we show the test results of relay system we developed.
In 2012, Sonwanshi et al. proposed an efficient smart card based remote user authentication scheme using hash function. They claimed that the scheme resists most current possible attacks. However, in the following year, Das et al. found that Sonwanshi et al.'s scheme is vulnerable to offline password guessing attack. In this paper, we point out that there… (More)
— In this paper, we look at the IEEE 802.16e or IEEE 802.16m based MBS and its problem of waste of resource. And we also look at new ways of MBS which have been introduced to overcome the disadvantage of waste of resource. Especially, we closely look at one of the new methods which dynamically configure the MBS region. And then, we show how many base… (More)
This paper presents a hybrid timer-based scheduling request scheme in wireless packet systems to provide quality-of-service for uplink multimedia transmission and also gives an analytic model for invalid allocation probability which can be used for estimating the performance of various uplink scheduling methods. The scheduling information request timer in… (More)
ion There are several laboratory-based mobile wireless testbeds such as the MeshTest and the CMU Wireless Emulator. These testbeds provide powerful computing network platforms for users who want to perform controlled, repeatable, mobile experiments in the lab. However, such systems can only use 10-15 nodes in an experiment. The Virtual Mesh Testbed (VMT)… (More)
—Security of ubiquitous computing systems is becoming more important along with extensive spread of the Internet applications. In this paper, we propose a key generation method for one-time password of Mobile-OTP systems by employing changed location and angle of fingerprint features. Fingerprint, as one powerful personal authentication tool, can create… (More)
— The purpose of this study was to propose the method to recognize gestures based on inertia sensor which recognizes the movements of the user using inertia sensor, simulated gesture recognition improvement using various neural network learning algorithms (Backpropagation, Fast-Backpropagation, and Levenberg-Marquardt) and lets the user enjoy the game by… (More)