Browsing by Author "Tseng, Yu-Chee"

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A Comparison of 4G Telecommunications Tariff Plans in Asia Countries
(2014)
Huang, Huai-Sheng
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Su, Tzu-Chung
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Wu, Jo-Ching
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Tsai, Wan-Du
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Tseng, Yu-Chee
Long Term Evolution (LTE) has been widely adopted by many 4G network operators. Many countries in America, Europe, and Asia have started LTE services since 2010. In the meantime, some countries (such as Taiwan and China) are in the process of transferring from 3G or Worldwide Interoperability for Microwave Access (WiMAX) to 4G services. In this paper, we investigate the tariff plans of the nine telecommunications operators which own top-three market shares in Singapore, Japan, and Hong Kong, respectively. Several issues, such as market share, tariff strategy, and even customs are discussed. Also, Tier-pricing strategies of LTE, such as Fair Use Policy (FUP), monthly data allowance, and data overage allowance, are discussed and compared. Moreover, we compare different charging plans and examine their price-performance ratios.
A Cross-Layer Framework for Overhead Reduction, Traffic Scheduling, and Burst Allocation in IEEE 802.16 OFDMA Networks
(2011-05-01)
Liang, Jia-Ming
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Chen, Jen-Jee
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Wang, You-Chiun
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Tseng, Yu-Chee
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資訊工程學系
IEEE 802.16 orthogonal frequency-division multiple access (OFDMA) downlink subframes have a special 2-D channel-time structure. Allocation resources from such a 2-D structure incur extra control overheads that hurt network performance. Existing solutions try to improve network performance by designing either the scheduler in the medium access control layer or the burst allocator in the physical layer, but the efficiency of overhead reduction is limited. In this paper, we point out the necessity of "codesigning" both the scheduler and the burst allocator to efficiently reduce overheads and improve network performance. Under the partial-usage-of-subcarriers model, we propose a cross-layer framework that covers overhead reduction, real-time and non-real-time traffic scheduling, and burst allocation. The framework includes a two-tier priority-based scheduler and a bucket-based burst allocator, which is more complete and efficient than prior studies. Both the scheduler and the burst allocator are tightly coupled together to solve the problem of arranging resources to data traffic. Given available space and bucket design from the burst allocator, the scheduler can well utilize the frame resource, reduce real-time traffic delays, and maintain fairness. On the other hand, with priority knowledge and resource assignment from the scheduler, the burst allocator can efficiently arrange downlink bursts to satisfy traffic requirements with low complexity. Through analysis, the cross-layer framework is validated to give an upper bound to overheads and achieve high network performance. Extensive simulation results verify that the cross-layer framework significantly increases network throughput, maintains long-term fairness, alleviates real-time traffic delays, and enhances frame utilization.
A Dynamic Hybrid Counting Procedure for eMBMS of 3GPP
(2017-01-01)
Huang, Yuehong
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Tseng, Yu-Chee
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資訊工程學系
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Department of Computer Science
In this paper, we identify two inefficiencies in the counting procedure of the evolved Multimedia Broadcast Multicast Service (eMBMS) in 3GPP: (1) it may consume too much network resources in determining the number of User Equipments (UEs) which are interested in receiving MBMS services, and (2) it is too conservative in that the counting results may be smaller than actual numbers because those UEs in the RRC_IDLE state are ignored (for avoiding RACH congestion). We then propose a new dynamic method by combining the theory of Geometric Splitting-based Estimation (GSE) and the theory of probability to accelerate the eMBMS counting procedure. Compared to the original eMBMS counting procedure, which only counts the UEs in the RRC_CONNECTED state, our scheme also counts the UEs in the RRC_IDLE state. However, our method still improves the accuracy of counting results and saves radio resources.
A Dynamic Reservation Scheme in Online Charging System for Family Shared Plan
(2015)
Huang, Huai-Sheng
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Su, Tzu-Chung
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Liang, Jia-Ming
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Tseng, Yu-Chee
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資訊工程學系
For simplifying billing and limiting data usage, Family Shared Plan (FSP) is now a popular plan provided by telecommunications operators. Based on the 3rd Generation Partnership Project (3GPP) specifications, Online Charging System (OCS) has to determine the Granted Unit (GU) and create reservations per session before a service is delivered by the serving network to a User Equipment (UE). However, fixed GUs cannot adapt to dynamic consumer behaviors, which usually require dynamic GUs. Clearly, giving small GUs will incur too many signaling messages for making reservations, but giving excessive GUs will cause unbalanced distribution of resources, especially in FSP cases. How to determine GUs is an open issue that can be self-defined by telecommunications operators. In this paper, we propose a new scheme for dynamically assigning GUs to UEs belonging to the same FSP, based on their historical data usage and total monthly data allowance. Simulation results show that our scheme can substantially save signalings by at least 22% compared to fixed scheme under unpredictable behaviors.
A Fast Handoff Mechanism for IEEE 802.11 and IAPP Networks
(2006)
Huang, Ping-Jung
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Tseng, Yu-Chee
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Tsai, Kun-Cheng
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資訊工程學系
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Department of Computer Science
Handoff is a critical issue in IEEE 802.11-based wireless networks. In this paper we propose a fast and seamless handoff solution for IEEE 802.11 wireless LAN with IAPP. It is based on a concept of neighbor graph, which describes the nearby access points (APs) that a mobile host (MH) may rind. Then we further derive selective scanning with unicast in power-save mode, pre-registration of IAPP, and frame forwarding-and-buffering mechanisms. Selective scanning allows a MH to only try potential handoff targets. Pre-registration allows early transfer of a MH\'s security context from its old AP to new AP. The forwarding-and-buffering mechanism is to solve the packet loss problem during handoff. Our performance evaluation shows that the proposed solution can result in 90% reduction in the handoff latency from standard handoff procedure.
A Fast Window-based Scalar Multiplication Algorithm for Elliptic Curve Cryptography in Wireless Sensor Networks
(2015-01-01)
Ye, Hung-Nan
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Wang, Kuochen
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Jan, Rong-Hong
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Hu, Yuh-Jyh
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Tseng, Yu-Chee
In this paper, we propose an enhanced window-based mutual opposite form (EW-MOF) for scalar multiplication with ECC in WSNs. The proposed EW-MOF combines MOF with an enhanced window method that can reduce not only pre-computation time and memory usage, but also average key generation time that includes pre-computation time in each sensor node. Our analysis has shown that the proposed EW-MOF requires a smaller number of essential pre-computed points than the one's complement. Therefore, it is very suitable for WSNs. Simulation results show that the proposed EW-MOF is 24.69% faster than the one's complement method, which is the best method available, in the average key generation time of ECC that includes pre-computation time under different field sizes. In summary, the proposed EW-MOF is more feasible than the one's complement for wireless sensor networks in terms of key generation time and power saving.
A Flexible Analysis and Prediction Framework on Resource Usage in Public Clouds
(2012)
Lin, Chia-Yu
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Chen, Yan-Ann
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Tseng, Yu-Chee
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Wang, Li-Chun
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資訊工程學系
In cloud computing environments, users can rent virtual machines (VMs) from cloud providers to execute their programs or provide network services. While using this kind of cloud services, one of the biggest problems for the users is to determine the proper number of VMs to complete the jobs considering both budget and time. In this paper, we propose a resource prediction framework (RPF), which can help users choose the minimum number of virtual machines to complete their jobs within a user specified time constraint. In order to verify the feasibility of RPF, we have done three case studies, namely parallel frequent pattern growth (FP-Growth), parallel K-means, and Particle Swarm Optimization (PSO). FP-growth, K-means and PSO are data intensive algorithms. These algorithms are typically executed repeatedly with different execution parameters to find the optimal results. When evaluating RPF by these algorithms in cloud environments, we have to modify them to parallel versions. The evaluation results indicate that RPF can successfully obtain the minimum number of VMs with acceptable errors. According to our case studies, the proposed RPF can be adopted by data intensive jobs by providing flexibility to both end users and cloud system providers.
A Framework for Simultaneous Message Broadcasting Using CDMA-Based Visible Light Communications
(2015-12-01)
Chen, Yan-Ann
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Chang, Yi-Ting
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Tseng, Yu-Chee
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Chen, Wen-Tsuen
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資訊工程學系
Internet of Things applications are fast growing recently. One of the things that has a lot of potential is the lighting equipment since it is widely used in our daily life. Recently, the technology of visible light communication (VLC) has been widely discussed. VLC has several advantages, such as freedom of license, line-of-sight security, and less health concern compared with radio-based systems. In addition, the rapid progress of light emitting diode (LED) technology by solid-sate lighting allows VLC to be easily deployed and integrated with the existing lighting infrastructure at low costs. However, VLC, when integrated with lighting infrastructure, is usually for one-way communication and is highly sensitive to external interfering light. Thus, transmitting or broadcasting multiple messages simultaneously over a visible light channel without any preprocessing may result in serious collisions. In this paper, we propose a framework to tackle these problems by optical code division multiple access (CDMA) for VLC. With our approach, a VLC receiver can enter an environment without any prior configuration and can be designed with simple hardware. Even a mobile device with a high-resolution photodiode sensor can be used as a receiver. We demonstrate an application of indoor positioning by querying the location service provider on the Internet with the IDs decoded from the received light signals. The prototyping results reveal some communication properties of CDMA-based VLC and its potential for indoor positioning applications.
A Hint-based Random Access Protocol for mMTC in 5G Mobile Network
(2018-01-01)
Xu, Yining
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Ren, Yi
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Lin, Kate Ching-Ju
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Tseng, Yu-Chee
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資訊工程學系
With the increasing popularity of machine-type communication (MTC) devices, several new challenges are encountered by the legacy long term evolution (LTE) system. One critical issue is that a massive number of MTC devices trying to conduct random access procedures may cause significant collisions and long delays. In this work, we present a new random access mechanism by splitting the contention-based preambles in LTE into two logically disjoint parts, one for the user equipment (UE) being paged and the other for the UEs not being paged. Since the IDs of paged UEs are known by the base station, a novel hash-based random access, which we call hint, is possible. The main idea is to pre-allocate preambles to paged UEs in a contention-free manner and confines non-paged UEs to contend in a separate region. We further build a mathematical model to find the optimal ratio of pre-allocated preambles. Extensive simulations are conducted to validate our results.
A Lightweight Network Repair Scheme for Data Collection Applications in ZigBee WSNs
(2009-09-01)
Pan, Meng-Shiuan
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Tseng, Yu-Chee
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資訊工程學系
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Department of Computer Science
Data collection is a fundamental operation in wireless sensor networks (WSNs). In [4], a quick convergecast solution is proposed for data collection in a ZigBee beacon-enabled tree-based WSN. However, it does not consider the network repair issue. When a ZigBee router loses its link to its parent, all its descendants have to rejoin the network. The rejoining procedure is time-consuming and may incur high communication overheads. The proposed network repair scheme consists of a regular repair and an instant repair schemes. Periodically, the network coordinator can issue regular repair to refresh the network (so as to keep the network in good shape). During normal operations, if a router loses its parent, it tries instant repair to reconnect to a new parent. Our design thus improves over ZigBee in that nodes can continue their operations even during instant repair.
A lightweight, self-adaptive lock gate designation scheme for data collection in long-thin wireless sensor networks
(2013-01-01)
Wang, You-Chiun
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Chuang, Che-Hsi
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Tseng, Yu-Chee
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Shen, Chien-Chung
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資訊工程學系
Constrained by the physical environments, the long-thin topology has recently been promoted for many practical deployments of wireless sensor networks (WSNs). In general, a long-thin topology is composed of a number of long branches of sensor nodes, where along a branch each sensor node has only one potential parent node toward the sink node. Although data aggregation may alleviate excessive packet contention, the maximum payload size of a packet and the dynamically changing traffic loads may severely affect the amount of sensor readings that may be collected along a long branch of sensor nodes. In addition, many practical applications of long-thin WSNs demand the exact sensor readings at each location along the deployment areas for monitoring and analysis purposes, so sensor readings may not be aggregated when they are collected. This paper proposes a lightweight, self-adaptive scheme that designates multiple collection nodes, termed lock gates, along a long-thin network to collect sensor readings sent from their respective upstream sensor nodes. The self-adaptive lock gate designation scheme balances between the responsiveness and the congestion of data collection while mitigating the funneling effect. The scheme also dynamically adapts the designation of lock gates to accommodate the time-varying sensor reading generation rates of different sensor nodes. A testbed of 100 Jennic sensor nodes is developed to demonstrate the effectiveness of the proposed lock gate designation scheme. Copyright (c) 2011 John Wiley & Sons, Ltd.
A multichain backoff mechanism for IEEE 802.11 WLANs
(2006-09-01)
Ye, Shiang-Rung
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Tseng, Yu-Chee
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資訊工程學系
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Department of Computer Science
The distributed coordination function (DCF) of IEEE 802.11 standard adopts the binary exponential backoff (BEB) for collision avoidance. In DCF, the contention window is reset to an initial value, i.e., CWmin, after each successful transmission. Much research has shown that this dramatic change of window size may degrade the network performance. Therefore, backoff algorithms, such as gentle DCF (GDCF), multiplicative increase-linear decrease (MILD), exponential increase-exponential decrease (EIED), etc., have been proposed that try to keep the memory of congestion level by not resetting the contention window after each successful transmission. This paper proposes a multichain backoff (MCB) algorithm, which allows stations to adapt to different congestion levels by using more than one backoff chain together with collision events caused by stations themselves as well as other stations as indications for choosing the next backoff chain. The performance of MCB is analyzed and compared with those of 802.11 DCF, GDCF, MILD, and EIED backoff algorithms. Simulation results show that, with multiple backoff chains and collision events as reference for chain transition, MCB can offer a higher throughput while still maintaining fair channel access than the existing backoff algorithms.
A Path-Connected-Cluster Wireless Sensor Network and Its Formation, Addressing, and Routing Protocols
(2012-06-01)
Tsai, Chia-Hung
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Tseng, Yu-Chee
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資訊工程學系
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Department of Computer Science
Although wireless sensor networks (WSNs) have been extensively researched, their deployment is still a main concern. We observe that many monitoring applications for WSNs have adopted a path- connected- cluster (PCC) topology, where regions to be monitored are deployed with clusters of sensor nodes. Since these clusters might be physically separated, paths of sensor nodes are used to connect them together. We call such networks PCC-WSNs. PCC-WSNs may be widely applied in real situations, such as bridge-connected islands, street-connected buildings, and pipe-connected ponds. In this paper, we show that the address assignment scheme defined by ZigBee will perform poorly in terms of address utilization. We then propose a systematical solution, which includes network formation, automatic address assignment, and light-weight routing. Simulation results verify the effectiveness of the proposed solution.
A Path-Connected-Cluster Wireless Sensor Network and Its Formation, Addressing, and Routing Protocols
(2012-06-01)
Tsai, Chia-Hung
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
Although wireless sensor networks (WSNs) have been extensively researched, their deployment is still a main concern. We observe that many monitoring applications for WSNs have adopted a path-connected-cluster (PCC) topology, where regions to be monitored are deployed with clusters of sensor nodes. Since these clusters might be physically separated, paths of sensor nodes are used to connect them together. We call such networks PCC-WSNs. PCC-WSNs may be widely applied in real situations, such as bridge-connected islands, street-connected buildings, and pipe-connected ponds. In this paper, we show that the address assignment scheme defined by ZigBee will perform poorly in terms of address utilization. We then propose a systematical solution, which includes network formation, automatic address assignment, and light-weight routing. Simulation results verify the effectiveness of the proposed solution.
A Proximity Sensor Based No-Touch Mechanism for Mobile Applications on Smart Phones
(2012-01-01)
Lin, Chia-Yu
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Chen, Yu-Jia
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Wang, Li-Chun
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Tseng, Yu-Chee
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電機工程學系
Smart phones with touch screens have become very popular and have changed our behaviors of using handsets. However, using touch screens is not safe for mobile phone users especially when they are driving cars. Thus, many applications using smart phones cannot be initiated because users who are driving the cars cannot easily touch the small icons on the screens of smart phones. To overcome this issue, we propose a proximity sensors based "no-touch" mechanism for smart phones by applying proximity sensors to initiate mobile applications without the need of touching the screen. We will discuss how to implement the proximity-sensors driven "no-touch" mechanism in Android platform and investigate its performance issues regarding detection accuracy and power consumption. Speech-oriented applications using the proposed "no-touch" mechanism on Android is also demonstrated in this paper.
A quorum-based mechanism as an enhancement to clock synchronization protocols for IEEE 802.11 MANETs
(2007-04-01)
Chen, Shu-Min
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Kuo, Sheng-Po
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Tseng, Yu-Chee
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資訊工程學系
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Department of Computer Science
In wireless mobile ad hoc networks (MANETs), it is essential that all mobile hosts (MHs) are synchronized to a common clock to support the power-saving (PS) mechanism. Many protocols have been proposed for clock synchronization in IEEE 802.11 MANETs. However, it is practically impossible for any protocol to completely solve the asynchronism problem especially when connectivity is achieved by multi-hop communication or when a network could be temporarily disconnected. In this work, we propose a quorum-based mechanism, which includes a new structure of beacon intervals for MHs to detect potential asynchronous neighbors and an enhanced beacon transmission rule to assist clock synchronization protocols to discover asynchronous neighbors within bounded time. The proposed mechanism should be regarded as an enhancement to existing clock synchronization protocols. Our simulation results show that the mechanism can effectively relieve the clock asynchronism problem for IEEE 802.11 MANETs.
A request control scheme for data recovery in DVB-IPDC systems with spatial and temporal packet loss
(2013-07-01)
Yang, Wen-Hsin
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Wang, You-Chiun
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Tseng, Yu-Chee
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Lin, Bao-Shuh Paul
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資訊工程學系
Recently, digital video broadcasting-handheld (DVB-H) and IP datacast over DVB-H (DVB-IPDC) have been developed to support broadcasting services. DVB-H is designed to support digital video broadcast for handheld devices, whereas DVB-IPDC can integrate with an IP-relay network to complement the data loss problem in DVB-H. Assuming that WiMAX networks are adopted to support DVB-IPDC, this paper points out two critical problems: group packet loss (GPL) and broadcast data handover (BDH). GPL occurs when there is a burst of retransmission requests for the same pieces of data with high spatial or temporal correlation. BDH happens when some devices that made the above requests handover to new serving cells. To solve these problems, we propose lazy wait and group acknowledgement schemes to alleviate duplicate requests by exploiting their spatial and temporal correlations. This not only reduces the requests submitted by neighboring devices in both space and time domains but also avoids handovering devices from sending duplicate requests in new cells. Through mathematical analysis, we show how to adaptively adjust the timers of lazy wait and group acknowledgement based on channel quality. Simulation results prove that our schemes can efficiently reduce retransmission requests and retransmission packets, thus alleviating congestion in the IP-relay network. Copyright (c) 2011 John Wiley & Sons, Ltd.
A scrambling method for fingerprint positioning based on temporal diversity and spatial dependency
(2008-05-01)
Kuo, Sheng-Po
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Tseng, Yu-Chee
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資訊工程學系
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Department of Computer Science
Signal strength fluctuation is one of the major problems in a fingerprint-based localization system. To alleviate this problem, we propose a scrambling method to exploit temporal diversity and spatial dependency of collected signal samples. We present methods on how these properties can be applied to enhance the positioning accuracy of several existing schemes. Simulation studies and experimental results show that the scrambling method can greatly improve positioning accuracy, especially when the tracked object has some degree of mobility.
A seamless handoff mechanism for DHCP-based IEEE 802.11 WLANs
(2007-08-01)
Chen, Jen-Jee
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Tseng, Yu-Chee
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Lee, Hung-Wei
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資訊工程學系
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Department of Computer Science
IEEE 802.11 wireless networks have gained great popularity. However, handoff is always a critical issue in this area. In this paper, we propose a novel seamless handoff mechanism for IEEE 802.11 wireless networks which support IEEE 802.11i security standard. Our approach consists of a Dynamic Tunnel Establishing procedure and a seamless handoff mechanism. Both intra- and inter-subnet handoff cases are considered in our seamless handoff approach. Our work focuses on handoffs in DHCP-based IP networks rather than Mobile IP-supported networks, but the proposed scheme can be easily tailored to Mobile IP-supported networks.
A sensor-based sun-tracking energy harvest system
(2015-01-01)
Tsai, Chia-Hung
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Hu, Shu-Chiung
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Huang, Chung-Hsiang
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Tseng, Yu-Chee
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資訊工程學系
Recent study has shown that the energy gain of a solar panel will be significantly influenced by the incidence angle of the sun radiation. The main goal of this paper is to present a sensor-based sun-tracking system. First, we design a sensing tower for measuring the direction of sun radiation. Then we design a sun-tracking algorithm, which adopts an iterative process to identify the direction of sun radiation to the earth\'s surface. This information is then passed to the nearby solar panels to adjust their angles. We have also developed a prototype and conducted several simulations to verify our sun-tracking system. Simulation results show that our system has better performance on the solar energy generation than existing ones.