B. J. Choi

Enhanced self-configuration scheme for a robust ZigBee-based home automation

In recent, ZigBee is considered as a potential solution for a scalable and flexible home automation systems. However, several constraints of the ZigBee might create node failure or frequent link breakages and thus some nodes in the network might become orphans. This orphan problem of ZigBee might bring a big confusion to a home automation environment in which a number of consumer devices are interconnected in the multi-hop manner. Therefore, in this paper, an enhanced self-configuration (ESC) scheme is proposed, which can improve the robustness of the conventional ZigBee-based home automation systems by coping well with orphan propagation problem and dynamic error environments. Through experiments on real system implementation, it is demonstrated that the ESC is superior to the conventional ZigBee network in terms of delay and robustness.

Link-Quality Measurement and Reporting in Wireless Sensor Networks

Wireless Sensor networks (WSNs) are created by small hardware devices that possess the necessary functionalities to measure and exchange a variety of environmental data in their deployment setting. In this paper, we discuss the experiments in deploying a testbed as a first step towards creating a fully functional heterogeneous wireless network-based underground monitoring system. The system is mainly composed of mobile and static ZigBee nodes, which are deployed on the underground mine galleries for measuring ambient temperature. In addition, we describe the measured results of link characteristics such as received signal strength, latency and throughput for different scenarios.

Faces detection method based on skin color modeling

This study suggests a method to improve the speed of a sliding window type of face detector by way of skin color region detection. The face detection method by way of skin color region detection has been studied in various perspectives: Complicated background images because of the area whose color is similar to the skin color cause high false positive rates. In contrast, the face detection method based on appearance, which adopts a sliding window type, may involve high face detection rates but cause tremendous computational costs in the process of detection scanning as the image size increases, whereas the processing time is also extended accordingly. This study suggests a method to control the subwindow size and detection area of a sliding window by detecting and using the skin color region with the processing time reduced. By means of a face detector with haar wavelet and LBP features, 274 images were collected online in addition to Bao database images, and then an experiment was conducted with them. As a result, the face detection time in utilization of an existing sliding window decreased down to a maximum of 47%.

A Novel Channel Sharing Scheme for Optimizing ODFC in IEEE 802.22 Systems

In this paper, a novel channel sharing scheme for IEEE 802.22 systems is introduced and its performance is investigated. In order to minimizing the number of user to share one channel, the status of backup channels, not occupied by any adjacent users, is checked. In addition, the condition of channels occupied by neighboring users is investigated. Based on these channel statuses, the proposed channel sharing scheme selects the optimal channel, which includes a non-occupied backup channel and the channel shared by least users, in order to change the channel currently in use with other users. The simulation results illustrate that significant performance enhancement is achieved by applying the proposed channel sharing scheme to IEEE 802.22 systems.

Steering behavior model of visitor NPCs in virtual exhibition

We propose steering behavior model to simulate virtual characters (NPC) which walk around in virtual exhibition environment and see exhibits one by one just like humans do. Steering behavior model of such environment has its significance in that it would raise the reality level of virtually recreated exhibition space such as museums or city area with points of attraction. However, currently available steering behavior models and techniques are improper to generate such behavior patterns. Our model is autonomous and individual–centric; virtual characters autonomously determine what exhibit they are going to see, in what order, at which view point, and how long, based on their personal preferences. We also describe the implementation of our model and provide the graphical results of simulations.

An Implementation of H.264 Intra Predictor Based on Sub-sampling

In order to reduce the computational complexity and the power consumption, sub-sampling technique applies for the H.264 intra predictor. Sub-sampling using some part of pixel values can reduce the amount of operation and exhibit the power reduction when compared to the case of intra prediction using all pixel values, although a coding gain of down remains negligible. With the 4:1 sub-sampling, the PSNR is decreased only by 0.1dB and the encoded bit size is increased by about 3% compared to the standard reference. Simulation results reveal a performance decrease up to 75% overall an amount of SAE operation and show a reduction of power consumption. The authors presented various performance indexes through implementing the intra-predictor of H.264 on virtual platform with MaxSimtrade environment

Rule-based soft computing for edge detection

In this paper, we present a robust rule-based edge detection method. Although generalized edge detection approaches are effective for most images they often fail in others. Thus the goal of our method is to provide more reliable edge detection results that are effective in most images. We implement the proposed method as follows: (1) transform RGB images to YCbCr format, (2) apply Sobel mask in four edge directions (horizontal, vertical, diagonal, anti-diagonal), (3) apply a bi-directional mask in four edge directions (horizontal–diagonal, vertical–diagonal, horizontal–anti-diagonal, vertical–anti-diagonal), and (4) detect rule-based edges by calculating membership degrees. Simulation results demonstrate that the proposed method is effective in most given images. We used three benchmarks approaches (Canny edge mask, high-pass filter, and Sobel mask) to compare the subjective performance quality.

Antenna switching scheme for downlink time switched transmit diversity with ARQ in the WCDMA LCR-TDD system

In this paper, the antenna switching scheme is proposed for Time Switched Transmit Diversity (TSTD) with ARQ (automatic repeat request) in WCDMA LCR-TDD systems, and the system performances are also investigated. The proposed TSTD system employs the ARQ scheme in which the receiver sends the acknowledgement signal (ACK or NACK) to the transmitter in order to predict the condition of the channel. For the ARQ-aided TSTD system, the proposed antenna switching pattern triggers the transmit antenna switches. Simulation results demonstrate that the performances of the TSTD systems can be improved by applying the ARQ scheme. Furthermore, the performances of ARQ-aided TSTD systems may be significantly improved by applying the proposed antenna switching scheme, especially when the mobile speed is low.

DiffServ–Aware MPLS scheme to support policy–based end–to–end qos provision in beyond 3g networks

3GPP proposes the policy-based network management to provide end–to–end QoS to services, and employs IntServ and DiffServ as policy enforcement means. Even if DiffServ is preferable to IntServ in scalability and configurability, it has the limitation of not being able to leverage multiple paths, hence undesirable in the network utilization aspect. In this paper, we propose DiffServ-aware Multiple Protocol Label Switching (MPLS) as a policy enforcement means. It enables to provide differentiated levels of QoS as well as to improve network utilization by splitting packets over multiple paths. It is also able to avoid the per–flow packet ordering problem occurring when splitting a flow into multiple paths by using a hashing–based scheme. We verify the effectiveness of our proposed scheme by the NS–2 based simulation.

Conclusion and Further Research ProblemsOFDM and MCCDMA for Broadband Multiuser Communications WLANS and Broadcasting. L.Hanzo, Mnster, T. Keller and B.J. Choi,

This chapter contains sections titled: Summary of Part I Summary and Conclusions of Part II Summary and Conclusions of Part III Closing Remarks