Browsing by Author "Feng, Kai-Ten"

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3-D Interactive Augmented Reality-enhanced Digital Learning Systems for Mobile Devices
(2013)
Feng, Kai-Ten
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Tseng, Po-Hsuan
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Chiu, Pei-Shuan
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Yang, Jia-Lin
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Chiu, Chun-Jie
With enhanced processing capability of mobile platforms, augmented reality (AR) has been considered a promising technology for achieving enhanced user experiences (UX). Augmented reality is to impose virtual information, e.g., videos and images, on to a live-view digital display. UX on real-world environment via the display can be effectively enhanced with the adoption of interactive AR technology. Enhancement on UX can be beneficial for digital learning systems. There are existing research works based on AR targeting for the design of e-learning systems. However, none of these work focuses on providing three-dimensional (3-D) object modeling for enhanced UX based on interactive AR techniques. In this paper, the 3-D interactive augmented reality-enhanced learning (IARL) systems will be proposed to provide enhanced UX for digital learning. The proposed IARL systems consist of two major components, including the markerless pattern recognition (MPR) for 3-D models and velocity-based object tracking (VOT) algorithms. Realistic implementation of proposed IARL system is conducted on Android-based mobile platforms. UX on digital learning can be greatly improved with the adoption of proposed IARL systems.
A heuristic energy-conserving multicast routing protocol for wireless multihop networks
(2007)
Huang, Yu-Zhi
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Liu, Wen-Jiunn
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Feng, Kai-Ten
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電信工程研究所
;
Institute of Communications Engineering
How to provide low energy consumption and high packet delivery ratio are considered the major issues in the protocol design for the wireless multihop networks. The main focus of this paper is to reduce the number of data transmissions such that the energy consumption can be decreased. In the wired networks, the Steiner-Tree is regarded as an optimal approach to construct the multicast structure for specific senders and receivers. However, it is considered an NP-Hard problem for achieving the minimum cost multicast tree under the wireless broadcast environment. In this paper, an Energy-Conserving Multicast Routing (ECMR) protocol is proposed as a heuristic scheme to reduce the number of relaying nodes for the construction of the multicast mesh. Moreover, the proposed algorithm is implemented on an ARM-based embedded platform for performance evaluation. Comparing with the existing multicast routing protocol, the experimental results show that the proposed ECMR scheme can provide better energy conservation while the packet delivery ratio is still preserved.
A Location and Mobility Aware Medium Access Control Protocol for Directional Antenna-Based Mobile Ad Hoc Networks
(2006)
Feng, Kai-Ten
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Lu, Chih-Ti
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電信工程研究所
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Institute of Communications Engineering
In recent years, the incorporation of the directional antennas within mobile devices has been studied in many areas. The usage of directional antennas can greatly reduce the radio interference, which results in improved utilization of the wireless medium. It becomes practical to exploit the directional antennas in the Medium Access Control (MAC) protocol design. In this paper, a Location and Mobility Aware (LMA) MAC protocol is developed for the mobile ad hoc networks. The predictive location of the mobile devices are adopted to enhance the robustness of the communication linkages while using the directional beams. The deafness problem is also alleviated using the directional listen (D-Listen) mechanism in the proposed algorithm. Under dynamic moving scenarios, both the spatial reuse and the routing efficiency are preserved using the proposed LMA MAC scheme. The performance of the proposed algorithm is evaluated and compared with other existing protocols in simulations.
A maximal power-conserving scheduling algorithm for broadband wireless networks
(2008)
Tseng, Hsin-Lung
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Hsu, Yu-Pin
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Hsu, Chung-Hslen
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Tseng, Po-Hslian
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Feng, Kai-Ten
The limitation on the battery lifetime has been a critical issue for the advancement of mobile computing. Different types of powersaving techniques have been proposed in various fields. In order to provide feasible energy conserving mechanism for the Mobile Subscriber Stations (MSSs), three powersaving types have been proposed for the IEEE 802.16e broadband wireless networks. However, these power saving types are primarily targeting for the cases with a single connection between the Base Station (BS) and the MSS. With the existence of multiple connections, the power efficiency obtained by adopting the conventional scheduling algorithm can be severely degraded. In this paper, a Maximal Power Conserving (MPC) scheduling algorithm is proposed to consider the aggregated effect from the multiple connections to the power efficiency. Moreover, the Quality of Service (QoS) constraints from both the downlink and the uplink traffic are employed in the design of the MPC algorithm in order to facilitate the corresponding MSS to fulfill its QoS requirements in both directions. Numerical results show that the proposed MPC scheduling algorithm outperforms the conventional 802.16e power saving mechanism, especially under the multi connection scenarios.
A Pitch-Aided Lane Tracking Algorithm for Driver Assistance System with Insufficient Observations
(2012)
Tang, Chi-Wai
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Feng, Kai-Ten
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Tseng, Po-Hsuan
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Chen, Chien-Hua
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Guo, Jing-Wei
The driver assistance system (DAS) is important to assist drivers with driving safety and efficiency. The lane departure warning system (LDWS), being an essential portion within the DAS, aims at providing warning messages under irregular driving behaviors due to distraction, drowsiness, or driver negligence. As the developments of mobile devices are boosted vigorously, it becomes more feasible to integrate sensing, photographing and displaying components within the LDWS. In this paper, the pitch-aided lane tracking (PALT) algorithm is proposed to detect and track the lanes on the roadways base on the particle filter. A pitch model is proposed to track the lane attributes associated with the pitch angle of a mobile device in order to conquer the effects from bumpy road and loosely-equipped of a mobile device. Moreover, the proposed PALT scheme can compensate the influences of insufficient observations from the display. Numerical results show that proposed PALT scheme can provide better lane-tracking performance compared to both original observations and the model without considering pitch angle.
A predictive location tracking algorithm for mobile devices with deficient signal sources
(2007)
Lin, Yu-Chiun
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Tseng, Po-Hsuan
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Feng, Kai-Ten
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電信工程研究所
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Institute of Communications Engineering
Location estimation and tracking for the mobile devices have attracted a significant amount of attention in recent years. The network-based location estimation schemes have been widely adopted based on the radio signals between the mobile device and the base stations. The location estimators associated with the Kalman filtering techniques are exploited to both acquire location estimation and trajectory tracking for the mobile devices. However, most of the existing schemes become unapplicable due to the insufficiency of signal sources. In this paper, a Predictive Location Tracking (PLT) algorithm is proposed to alleviate this problem. The predictive information obtained from the Kalman filter is employed to provide the additional signal inputs for the location estimators. The proposed PLT scheme can offer persistent accuracy for location tracking of the mobile devices, especially with inadequate signal sources. Numerical results demonstrate that the proposed PLT algorithm can achieve better precision, comparing with other existing schemes, in mobile location estimation and tracking.
A predictive movement based handover algorithm for broadband wireless networks
(2008)
Tseng, Po-Hsuan
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Feng, Kai-Ten
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電信工程研究所
;
Institute of Communications Engineering
The design of an efficient handover technique is considered as one of the crucial topics in the cellular based wireless networks. Feasible handover process can minimize the performance degradation as the mobile device is moving between different base stations. Based on the IEEE 802.16e standard, it is required to provide satisfactory handover performance under a wide range of moving speeds of the mobile device. In this paper, a predictive movement based handover (PMHO) algorithm is proposed. Without incurring excessive overheads as from the conventional location estimation and tracking techniques, the proposed sideline traveling scheme within the PMHO algorithm employs the moving state indicator (MSI) to predict the potential moving characteristics of the mobile device. The handover decision of the PMHO approach is determined based on the MSI values associated with the neighbor base stations. Numerical results show that the proposed PMHO algorithm can effectively reduce both the number of handover and the size of the neighbor scanning set within the mobile device.
A QUEUEING-THEORETICAL FRAMEWORK FOR QOS-ENHANCED SPECTRUM MANAGEMENT IN COGNITIVE RADIO NETWORKS
(2011-12-01)
Wang, Li-Chun
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Wang, Chung-Wei
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Feng, Kai-Ten
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電機工程學系
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電信工程研究所
This article outlines the fundamental modeling issues of opportunistic spectrum access in cognitive radio networks. In particular, we identify the effects of connection-based channel usage on the QoS performance of spectrum management techniques. During the transmission period of a secondary user's connection, the phenomenon of multiple spectrum handoffs due to interruptions of primary users arises quite often. In addition to multiple interruptions, the connection-based channel usage behaviors are also affected by spectrum sensing time, switching between different channels, generally distributed service time, and channel contention between multiple secondary users. An analytical framework based on the preemptive resumption priority M/G/1 queueing theory is introduced to characterize the effects of the above factors simultaneously. The proposed generalized analytical framework can incorporate various system parameters into the design of very broad spectrum management techniques, including spectrum sensing, spectrum decision, spectrum sharing, and spectrum mobility. The applications of this analytical framework on spectrum decision as well as spectrum mobility are discussed, and some open issues using this framework are suggested in this article.
A Statistical Power-Saving Mechanism for IEEE 802.16 Networks
(2009)
Hsu, Chung-Hsien
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Feng, Kai-Ten
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The power-saving class of type I (PSC I), one of the sleep mode operations in the IEEE 802.16e standard, is designed to reduce power consumption for non-real-time traffic. However, the inefficiency of PSC I comes from its configuration and operation. Based on the notions of IEEE 802.16m sleep mode operation, a statistical sleep window control (SSWC) approach is proposed to improve energy efficiency for mobile stations in this paper. The SSWC approach exploits a partially observable Markov decision process (POMDP) to conjecture the present traffic state. Based on the properties of POMDP, the optimal policy for sleep window selection is acquired in the SSWC approach. The performance evaluation is conducted and compared via the simulations. Simulation results show that the proposed SSWC approach outperforms the IEEE 802.16e PSC I scheme and the inferred IEEE 802.16m power-saving mechanism.
A Survey: Green Energy for Cellular Base Station and Small Cell
(2017-01-01)
Tala't, Mohammad
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Yu, Chih-Min
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Feng, Kai-Ten
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電機工程學系
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Department of Electrical and Computer Engineering
Recently green energy is one of the promising solutions for wireless communication to decrease the power consumption in term of reducing foot carbon emissions. One of the high challenges is to find the optimal solution for wireless communication especially heterogeneous networks taking into account maintaining the quality of service (QoS) of the connection. This paper investigates several methods to find the optimal solution for the heterogeneous network including cellular base station and small cell base stations (SBSs) using renewable energy. We present briefly the recent methods and policies to achieve the optimal solution. Lastly, we suggest some ideas that it can efficiently improve the performance of current solutions with guaranteed QoS.
Adaptive GPS Acquisition Technique in Weak Signal Environment
(2006)
Chuang, Ming-Yu
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Feng, Kai-Ten
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電信工程研究所
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Institute of Communications Engineering
In recent years, there has been increasing demands in providing precise location estimation in weak signal environment (e.g. in urban area or inside a building). Conventional GPS acquisition techniques are considered to be adequate on positioning capability in outdoor environment. However, most of them are not satisfactory for applications with weak signals. It has been studied that a longer time of data integration is required in order to provide sufficient data for acquisition under weak signal circumstances. In this paper, an adaptive GPS acquisition technique is proposed, which adaptively adjusts the detection threshold and the length of data integration for signal acquisition. The location of the navigation bit-transition is perceived within the acquisition data in order to adaptively determine either the coherent or the differential coherent combining method should be used. The simulation results show that the proposed adaptive acquisition technique outperforms both the non-coherent combining and the differential-coherent combining algorithms. As the SNR value of the incoming signal decreases, the effectiveness of the proposed adaptive scheme can be observed.
Adaptive point-to-point communication approach for subscriber stations in broadband wireless networks
(2011-01-01)
Hsu, Chung-Hsien
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Feng, Kai-Ten
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電機工程學系
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Department of Electrical and Computer Engineering
The point-to-multipoint (PMP) mode is considered the well-adopted transmission type that is supported by the IEEE 802.16 standard. The base station (BS) is served as the centralized coordinator to control and forward packets for the subscriber stations (SSs) within the network. In the case that two SSs intend to conduct packet transmission, it is required for the packets to be rerouted to the BS before arriving at the destination SS. The communication bandwidth is apparently wasted due to the rerouting processes. In this paper, an adaptive point-to-point communication (APC) approach is proposed to achieve direct communication between SSs within the PMP mode of the IEEE 802.16 standard. The BS is coordinating and arranging specific time intervals for the two SSs that are actively involved in packet transmission. Based on channel conditions among the BS and the SSs, the packet transmission operation is switched between direct communication and indirect communication in the APC approach. Both the architectural design and analytical modeling of the proposed scheme are conducted in this paper. The effectiveness of the proposed APC approach in terms of user throughput and its corresponding overhead can be observed via both the analytical and simulation results.
An Enhanced Predictive Location Tracking Scheme with Deficient Signal Sources for Wireless Networks
(2009)
Tseng, Po-Hsuan
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Feng, Kai-Ten
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Location estimation and tracking for the mobile devices have attracted a significant amount of attention in recent years. The location estimators associated with the Kalman filtering techniques are exploited to both acquire location estimation and trajectory tracking for the mobile devices. However, most of the existing schemes become inapplicable for location tracking due to the deficiency of signal sources. In this paper, the enhanced predictive location tracking (EPLT) are proposed to alleviate this problem. The EPLT scheme utilizes the predictive information obtained from the Kalman filter in order to provide the additional signal inputs for the location estimator. Furthermore, the EPLT scheme incorporates the geometric dilution of precision (GDOP) information into the algorithm design. Persistent accuracy for location tracking can be achieved by adopting the proposed EPLT scheme, especially with inadequate signal sources. Numerical results demonstrate that the EPLT algorithm can achieve better precision in comparison with other location tracking schemes.
An MIMO Configuration Mode and MCS Level Selection Scheme by Fuzzy Q-Learning for HSPA(+) Systems
(2012-07-01)
Chung, Wen-Ching
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Chang, Chung-Ju
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Feng, Kai-Ten
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Chen, Ying-Yu
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電機工程學系
In this paper, we propose a fuzzy Q-learning-based MIMO configuration mode and MCS level (FQL-MOMS) selection scheme for high speed packet access evolution (HSPA(+)) systems. The FQL-MOMS selection scheme intends to enhance the system throughput under the block error rate (BLER) requirement guarantee. It will determine an appropriate MIMO configuration mode and MCS (modulation and coding scheme) level for packet data transmission in HSPA(+) systems, under the situations that the channel status is varying and the channel quality indication (CQI) has report delay. The FQL-MOMS scheme considers not only the reported CQI and the last transmission result but also the BLER performance metric and the transmission efficiency. Moreover, it is effectively configured, where the fuzzy rules and the reinforcement signals for the Q-learning algorithm are sophisticatedly designed. Simulation results show that the proposed FQL-MOMS scheme increases the system throughput by up to 49.3 and 35.9 percent, compared to the conventional adaptive threshold selection (ATS) scheme [12] and the Q-HARQ scheme [14], respectively, under the BLER requirement fulfillment.
An unified Kalman tracking technique for wireless location systems
(2007)
Tseng, Po-Hsuan
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Chen, Chao-Lin
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Feng, Kai-Ten
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電信工程研究所
;
Institute of Communications Engineering
Location estimation and tracking for the mobile stations have attracted a significant amount of attention in recent years. In order to offer sufficient precision for wireless location tracking, different techniques have been studied and combined, e.g. the Least Square methods for location estimation associated with the Kalman filters for location tracking. In this paper, an Unified Kalman Tracking (UKT) technique is proposed to provide an integrated algorithm for precise location estimation and tracking. Based on the Time-Of-Arrival (TOA) measurements, a new variable is incorporated as an additional state within the Kalman filtering formulation in order to consider the nonlinear behavior for wireless location estimate. Numerical results illustrate that the proposed UKT algorithm can achieve enhanced accuracy for mobile location tracking, comparing with other existing schemes.
Analysis and determination of cooperative MAC strategies from throughput perspectives
(2013-08-01)
Chu, Jui-Hung
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Feng, Kai-Ten
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Liao, Chun-Chieh
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電機資訊學士班
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Undergraduate Honors Program of Electrical Engineering and Computer Science
In recent years, cooperative communication has been developed as a new communication strategy that incorporates a relay node to assist direct point-to-point transmission. By exploiting cooperative diversity, different types of techniques have been proposed to improve transmission reliability from the physical layer perspective. However, owing to the longer transmission time resulting from the cooperative schemes, there is no guarantee to enhance network throughput in view of the medium access control (MAC) performance. In this paper, system throughput of combined direct/cooperative communication is evaluated by exploiting the proposed analytical model based on the IEEE 802.11 MAC protocol. The feasibility of adopting either cooperative or direct communication is also studied in the analytical model. In terms of network throughput, whether to adopt cooperative schemes depends on the tradeoff between cooperative transmission delay and channel quality of direct communication. Moreover, two cooperative MAC protocols are proposed to determine the circumstances to activate cooperative communication according to the channel quality. The full-channel quality indicator based cooperative (FCC) MAC protocol is introduced to choose both the transmission scheme and the relay node according to the full channel quality information. However, the overhead caused by the FCC scheme can degrade the throughput performance as the number of available relays is significantly increased. Therefore, the bitwise competition based cooperative (BCC) MAC protocol is utilized to efficiently determine a feasible relay node for data transmission. Simulations are performed to validate the effectiveness of proposed analytical models and cooperative MAC protocols. It is observed that the proposed BCC scheme can outperform both the FCC protocol and conventional direct transmission with enhanced system throughput.
Analytical Modeling and Design of Energy Efficient Class-Selection for Long Range Wide Area Networks
(2019-01-01)
Su, Wun-Ci
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Wu, Tzu-I
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Li, Pei-Rong
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Feng, Kai-Ten
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電信工程研究所
Long range wide area networks (LoRaWAN) is one of the novel specification for the applications of Internet-of-Things. Recent research focused on the propagation model and coverage discussion based on experimental measurement. In this paper, power-class analytical model is firstly proposed to model the operations of LoRaWAN end-devices for throughput and power consumption. Based on this model, the energy efficient class-selection algorithm (EECA) is proposed to achieve the optimal energy efficiency with the consideration of power consumption on end-devices by the suitable class selection scheme. A system level simulation has been conducted for performance evaluation. The simulation results provide the guideline for system parameters configuration and class selection on each end-devices under different scenarios.
Automatic Hybrid Access Point Deployment for Wireless Localization Systems
(2017-01-01)
Hung, Yun-Ting
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Feng, Kai-Ten
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Tseng, Po-Hsuan
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電機工程學系
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Department of Electrical and Computer Engineering
Location estimation has received wide attention due to the emerging demand for location-based services (LBSs) in indoor environments. Although positioning algorithms have been rapidly developed, the positioning accuracy has not reached the requirement of indoor LBSs. Indoor positioning methods based on the existing communication systems such as Wi-Fi or Bluetooth have the advantage of lower cost and higher penetration rates, which can provide a sufficient number of signal sources. Unlike the global positioning system where the satellites are well-deployed to provide four or more signal sources and well-conditioned geometric for outdoor devices, the critical limits of indoor positioning are the insufficient signal sources and disunified deployment for access points (APs). To address the problem, we propose an automatic hybrid AP deployment (AHAD) algorithm to provide optimal locations and required numbers of both Wi-Fi APs and BLE APs for achieving higher location estimation accuracy. With the adoption of genetic algorithm, the AHAD scheme can maintain satisfactory Wi-Fi communication quality and fulfill user's budget for AP deployment. Furthermore, a hybrid indoor positioning (HIP) scheme is also proposed based on the combination of Wi-Fi fingerprinting and BLE proximity. Experimental results show that the proposed AHAD algorithm can provide better location estimation accuracy compared to conventional AP deployment based on user instinct.
Channel-Aware Resource Allocation for Energy-Efficient Cloud Radio Access Networks Under Outage Specifications
(2017-11-01)
Li, Pei-Rong
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Feng, Kai-Ten
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電機工程學系
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Department of Electrical and Computer Engineering
This paper investigates a cloud radio access network (C-RAN) architecture for future wireless network, which focuses on centralized processing for spatially distributed remote radio heads (RRHs). Our main goal is to promote an energy efficient C-RAN under the consideration of multiple access interference (MAI) and imperfect channel state information at the transmitter (CSIT) via outage-aware resource allocation. The closed-form expression of fading-induced outage probability for each transceiver pair will be established by analyzing the statistical property of signal-to-interference-plus-noise. In the course of finding feasible solutions to enhance energy efficiency, the optimization procedures named C-RAN-based energy efficient power allocation (CEEPA) and low-complexity CEEPA are proposed. As the number of RRHs grows to infinity, the deterministic equivalents of performance metrics can be derived by applying recent results from random matrix theorem, which lead to an efficient way to obtain the asymptotic-optimal resource allocation policy. Also, the regularized zero-forcing precoding technique is adopted to mitigate MAI and can tackle the impact of imperfect CSIT thanks to the derivation of deterministic equivalents. Numerical simulations show that the proposed resource allocation schemes can provide better energy efficiency and the accuracy of asymptotic expressions is also verified. Furthermore, the merit of a distributed antenna system is demonstrated through the comparison with centralized antenna system.
Cloud Computing Based Mobile Augmented Reality Interactive System
(2014)
Chiu, Pei-Hsuan
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Tseng, Po-Hsuan
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Feng, Kai-Ten
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電機工程學系
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Department of Electrical and Computer Engineering
Augmented reality (AR) technology is mainly composed of feature extraction, feature points matching and 3-D object drawing to impose virtual information onto the real camera. Hand tracking method is designed to realize interactive AR system to further enhance user experience (UX). However, feature extraction, feature points matching, and hand tracking all require high computational cost. To achieve real-time implementation on mobile, we proposed a Mobile Augmented ReAlity Interactive System based on cloud computing (MARAIS). Cloud side is responsible for heavy tasks that need sufficient computational capabilities, and device side performs sensing, detecting and displaying. Device/cloud architecture has been designed to maintain tolerable processing delay with minimum communication overhead. To validate the suitability for real-time interaction, MARAIS is combined with a picture book to realize a digital learning system. Implementation of interactive AR system based on cloud computing eases the requirement of data storage, memory, and computational power at device side.