고속 전송률 UWB 시공간 부호화 OFDM

이광재,이문호,Hsiao-Hwa Chen 대한전자공학회 2006 電子工學會論文誌-TC (Telecommunications) Vol.43 No.7

In this paper, we present a candidate high data rate space time coded OFDM system for short range personal networking. The system transmits the complex space time coded signals with a hybrid orthogonal frequency division multiplexing (OFDM) based on ultra wideband (UWB) pulses. The transmitted signals are sparse pulse trains modulated by a frequency selected from a properly designed set of frequencies. Additionally, a widely linear (WL) receive filter and a space time frequency transmission are designed by using two simple parallel linear detectors. To overcome the deeply fade in the propagation system, a beamforming combined with space time block codes also are briefly discussed. 본 논문에서는 단거리 개인 네트워킹을 위한 고속 전송률 UWB 시공간 부호화 OFDM 시스템을 제시한다. 본 시스템은 UWB 펄스를 토대로 하는 혼성 OFDM 신호와 함께 복소 시공간 부호화 신호를 송신한다. 송신 신호는 적절히 설계된 주파수 집합으로부터 선별된 주파수에 의해 변조된 희소 펄스열이다. 부수적으로 WL(widely linear) 수신 여파기와 시간-주파수 공간 전송은 단순한 병렬 선형 검파기를 이용하여 설계한다. 또한, 전파 시스템에서 깊은 페이딩을 극복하기 위해 시공간 블록 부호와 결합한 빔성형을 간략히 고찰한다.

Comparative Analysis of Logistic Regression, Support Vector Machine and Artificial Neural Network for the Differential Diagnosis of Benign and Malignant Solid Breast Tumors by the Use of Three-Dimensional Power Doppler Imaging

Shou-Tung Chen,Yi-Hsuan Hsiao,Yu-Len Huang,Shou-Jen Kuo,Hsin-Shun Tseng,Hwa-Koon Wu,Dar-Ren Chen 대한영상의학회 2009 Korean Journal of Radiology Vol.10 No.5

Objective: Logistic regression analysis (LRA), Support Vector Machine (SVM) and a neural network (NN) are commonly used statistical models in computeraided diagnostic (CAD) systems for breast ultrasonography (US). The aim of this study was to clarify the diagnostic ability of the use of these statistical models for future applications of CAD systems, such as three-dimensional (3D) power Doppler imaging, vascularity evaluation and the differentiation of a solid mass. Materials and Methods: A database that contained 3D power Doppler imaging pairs of non-harmonic and tissue harmonic images for 97 benign and 86 malignant solid tumors was utilized. The virtual organ computer-aided analysis-imaging program was used to analyze the stored volumes of the 183 solid breast tumors. LRA, an SVM and NN were employed in comparative analyses for the characterization of benign and malignant solid breast masses from the database. Results: The values of area under receiver operating characteristic (ROC) curve, referred to as Az values for the use of non-harmonic 3D power Doppler US with LRA, SVM and NN were 0.9341, 0.9185 and 0.9086, respectively. The Az values for the use of harmonic 3D power Doppler US with LRA, SVM and NN were 0.9286, 0.8979 and 0.9009, respectively. The Az values of six ROC curves for the use of LRA, SVM and NN for non-harmonic or harmonic 3D power Doppler imaging were similar. Conclusion: The diagnostic performances of these three models (LRA, SVM and NN) are not different as demonstrated by ROC curve analysis. Depending on user emphasis for the use of ROC curve findings, the use of LRA appears to provide better sensitivity as compared to the other statistical models. Objective: Logistic regression analysis (LRA), Support Vector Machine (SVM) and a neural network (NN) are commonly used statistical models in computeraided diagnostic (CAD) systems for breast ultrasonography (US). The aim of this study was to clarify the diagnostic ability of the use of these statistical models for future applications of CAD systems, such as three-dimensional (3D) power Doppler imaging, vascularity evaluation and the differentiation of a solid mass. Materials and Methods: A database that contained 3D power Doppler imaging pairs of non-harmonic and tissue harmonic images for 97 benign and 86 malignant solid tumors was utilized. The virtual organ computer-aided analysis-imaging program was used to analyze the stored volumes of the 183 solid breast tumors. LRA, an SVM and NN were employed in comparative analyses for the characterization of benign and malignant solid breast masses from the database. Results: The values of area under receiver operating characteristic (ROC) curve, referred to as Az values for the use of non-harmonic 3D power Doppler US with LRA, SVM and NN were 0.9341, 0.9185 and 0.9086, respectively. The Az values for the use of harmonic 3D power Doppler US with LRA, SVM and NN were 0.9286, 0.8979 and 0.9009, respectively. The Az values of six ROC curves for the use of LRA, SVM and NN for non-harmonic or harmonic 3D power Doppler imaging were similar. Conclusion: The diagnostic performances of these three models (LRA, SVM and NN) are not different as demonstrated by ROC curve analysis. Depending on user emphasis for the use of ROC curve findings, the use of LRA appears to provide better sensitivity as compared to the other statistical models.

ARCA-An Adaptive Routing Protocol for Converged Ad-Hoc and Cellular Networks

Wu, Yumin,Yang, Kun,Chen, Hsiao-Hwa The Korea Institute of Information and Commucation 2006 Journal of communications and networks Vol.8 No.4

This paper proposes an adaptive routing protocol called ARCA for converged ad-hoc and cellular network (CACN). Due to the limitation of both bandwidth and transmission range in a cell, a mobile host (MH) may not be able to make a call during busy time. CACN offers a flexible traffic diversion mechanism that allows a MH to use the bandwidth in another cell to ease the congestion problem and increase the throughput in a cellular network. Based on the presentation of CACN's physical characteristics, the paper details the design issues and operation of the adaptive routing protocol for CACN (ARCA). Detailed numerical analysis is presented in terms of both route request rejection rate and routing overhead, which, along with the simulation results, have indicated the effectiveness and efficiency of the ARCA protocol.

Broadband convergence Network (BcN)

Jamalipour, Abbas,Kato, Nei,Chen, Hsiao-Hwa,Jun, Kyung-Pyo The Korean Institute of Communications and Informa 2006 Journal of communications and networks Vol.8 No.4

Applications of Intelligent Radio Technologies in Unlicensed Cellular Networks - A Survey

( Yi-feng Huang ),( Hsiao-hwa Chen ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.7

Demands for high-speed wireless data services grow rapidly. It is a big challenge to increasing the network capacity operating on licensed spectrum resources. Unlicensed spectrum cellular networks have been proposed as a solution in response to severe spectrum shortage. Licensed Assisted Access (LAA) was standardized by 3GPP, aiming to deliver data services through unlicensed 5 GHz spectrum. Furthermore, the 3GPP proposed 5G New Radio-Unlicensed (NR-U) study item. On the other hand, artificial intelligence (AI) has attracted enormous attention to implement 5G and beyond systems, which is known as Intelligent Radio (IR). To tackle the challenges of unlicensed spectrum networks in 4G/5G/B5G systems, a lot of works have been done, focusing on using Machine Learning (ML) to support resource allocation in LTE-LAA/NR-U and Wi-Fi coexistence environments. Generally speaking, ML techniques are used in IR based on statistical models established for solving specific optimization problems. In this paper, we aim to conduct a comprehensive survey on the recent research efforts related to unlicensed cellular networks and IR technologies, which work jointly to implement 5G and beyond wireless networks. Furthermore, we introduce a positioning assisted LTE-LAA system based on the difference in received signal strength (DRSS) to allocate resources among UEs. We will also discuss some open issues and challenges for future research on the IR applications in unlicensed cellular networks.

Classification and Experimental Analysis for Clone Detection Approaches in Wireless Sensor Networks

Kwantae Cho,Minho Jo,Taekyoung Kwon,Hsiao-Hwa Chen,Dong Hoon Lee IEEE 2013 IEEE systems journal Vol.7 No.1

<P>Wireless sensor networks (WSNs) consist of tiny sensor nodes that communicate with each other over wireless channels, often in a hostile environment where nodes can be captured and compromised. Consequently, an adversary may launch a clone attack by replicating the captured nodes to enlarge the compromised areas employing clones. Thus, it is critical to detect clone nodes promptly for minimizing their damage to WSNs. Recently, various clone detection schemes were proposed for WSNs, considering different types of network configurations, such as device types and deployment strategies. In order to choose an effective clone detection scheme for a given sensor network, the selection criteria play an important role. In this paper, we first investigate the selection criteria of clone detection schemes with regard to device types, detection methodologies, deployment strategies, and detection ranges. We then classify the existing schemes according to the proposed criteria. Simulation experiments are conducted to compare their performances. It is concluded that it is beneficial to utilize the grid deployment knowledge for static sensor networks; the scheme using the grid deployment knowledge can save energy by up to 94.44% in comparable performance (specifically in terms of clone detection ratio and the completion time), as compared to others. On the other hand, for mobile sensor networks, no existing approach works efficiently in reducing detection error rate.</P>

Quasi-Quadrature Modulation Method for Power-Efficient Video Transmission Over LTE Networks

Maksymyuk, Taras,Longzhe Han,Xiaohu Ge,Hsiao-Hwa Chen,Minho Jo IEEE 2014 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.63 No.5

<P>New emerging services, such as real-time video streaming or video on demand, are causing rapid growth in packet transmission over wireless networks. Unlike voice calls, for which the duration is usually not very long, video streaming applications require continuous transmission for a long time. Therefore, video streaming applications in mobile networks consume more energy compared with voice calls. Thus, the task of optimizing data transmission algorithms has become more important during the last few years. Apparently, the majority of multimedia traffic is video transmission. These applications consume much more power, compared with audio or general data transmission, because of higher throughput requirements. This paper addresses the problem of decreasing power consumption due to video transmission applications in Long-Term Evolution (LTE) networks. There are existing solutions for managing power consumption during video transmission. In particular, Third-Generation Partnership Project LTE Advanced (LTE-A) has defined the discontinuous reception/transmission (DRX/DRT) mechanism to allow devices to turn off their radio interfaces and go to sleep in various patterns. Some other similar solutions suggest DRX/DRT optimization to maximize the sleep periods of devices while guaranteeing quality of service in multimedia applications. However, existing solutions for packet transmission optimization are not very effective without physical-layer optimization. However, existing solutions for packet transmission optimization are not very effective without physical-layer optimization. We suggest a new method of modulation for improving energy efficiency of wireless video transmission. Four different schemes of quasi-quadrature modulation using multiple-input-multiple-output (MIMO) techniques with different quality of service performances are proposed in this paper. We simulate H.264/AVC video transmission. Results confirm the theoretical analysis. The proposed approach is able to improve energy efficiency while providing the same packet loss probability.</P>