Browsing by Author "Tseng, Chien-Chao"

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A Backbone-Aware Topology Formation (BATF) Scheme for ZigBee Wireless Sensor Networks
(2013-01-01)
Huang, Kuei-Li
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Yen, Li-Hsing
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Wang, Jui-Tang
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Wu, Chao-Nan
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Tseng, Chien-Chao
In a tree-structured ZigBee wireless sensor network, nodes close to the root of the tree (i.e., hot-spot nodes) may exhaust their power earlier than those distant from the root due to heavy loads on packet forwarding. This hot-spot problem is inherent in tree-structured networks and may demand extra energy to recover from failures of hot-spot nodes. In this paper, the backbone-aware topology formation (BATF) scheme is proposed to alleviate the hot-spot problem. BATF utilizes power-rich nodes to form a backbone tree that does not suffer from the hot-spot problem. Each power-rich node independently initiates a ZigBee tree network that attracts associations from ZigBee-compliant devices in order to distribute packet-forwarding loads over a larger set of nodes. Issues of BATF such as the partition of address space and ZigBee-compliant routing are discussed in detail. Simulation results confirm that BATF does alleviate the hot-spot problem as it improves network lifetime as well as data collection capability. Comparisons with native ZigBee protocols show that the improvement comes from our protocol design rather than simply introducing power-rich nodes.
A Bandwidth-sharing Reservation Scheme to Support QoS for Network Mobility
(2006-01-01)
Wang, Jui-Tang
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Hsu, Yuan-Ying
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
A NEtwork that is MObile (NEMO) usually consists of at least one Mobile Router (MR) attached to the infrastructure to manage all external communication for this moving network. Users inside a NEMO might also require quality of services (QoS) guarantee while accessing the Internet via a mobile device. In this paper, we propose a Bandwidth-sharing Reservation (BSR) scheme so that a NEMO can support QoS services. The proposed BSR scheme establishes a bandwidth sharing reservation tunnel for all NEMO nodes to efficiently utilize external bandwidth of MR, and it makes advance reservations at neighboring networks to solve the mobility problem. Three reservation adjustment policies are designed to further improve bandwidth utilization. Both mathematical analysis and simulation results show that the proposed BSR scheme can significantly increase bandwidth utilization and decrease handoff blocking rate while providing QoS services to NEMO nodes in movement.
A Bandwidth-sharing Reservation Scheme to Support QoS for Network Mobility
(2006-01-01)
Wang, Jui-Tang
;
Hsu, Yuan-Ying
;
Tseng, Chien-Chao
;
資訊工程學系
;
Department of Computer Science
A NEtwork that is MObile (NEMO) usually consists of at least one Mobile Router (MR) attached to the infrastructure to manage all external communication for this moving network. Users inside a NEMO might also require quality of services (QoS) guarantee while accessing the Internet via a mobile device. In this paper, we propose a Bandwidth-sharing Reservation (BSR) scheme so that a NEMO can support QoS services. The proposed BSR scheme establishes a bandwidth sharing reservation tunnel for all NEMO nodes to efficiently utilize external bandwidth of MR, and it makes advance reservations at neighboring networks to solve the mobility problem. Three reservation adjustment policies are designed to further improve bandwidth utilization. Both mathematical analysis and simulation results show that the proposed BSR scheme can significantly increase bandwidth utilization and decrease handoff blocking rate while providing QoS services to NEMO nodes in movement.
A Case Study of Cache Performance in ICN - Various Combinations of Transmission Behavior and Cache Replacement Mechanism
(2015)
Ho, Cheng-Yun
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Ho, Cheng-Yuan
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
Information-centric networking (ICN) is suggested by many papers and research projects to improve network performance and enhance network resource efficiency in recent years. Moreover, in these researches, some researchers not only proposed their ideal ICN approaches but also modified the existing cache replacement mechanism to fit their ICN approaches. In this paper, we aim at investigating and quantifying the effect of the cache hit ratio with two kinds of transmission behavior, sequential and un-sequential, and three cache replacement mechanisms, FIFO, LRU, and random, in ICN. We implement several simulations with ndnSIM under NS-3 simulator. The simulation results show that LRU and FIFO are suitable for all networking applications no matter sequential or un-sequential content transmission behavior is used. Besides, the simulation results reveal that the cache hit ratios in LRU and FIFO are same when the experiment settings are with same interest packets sending rate, same experiment time, and sequential content transmission behavior.
A Cross-Layer Architecture for Service Continuity and Multipath Transmission in Heterogeneous Wireless Networks
(2013)
Chan, Min-Cheng
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Tseng, Chien-Chao
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Yen, Li-Hsing
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資訊工程學系
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Department of Computer Science
Mobile devices equipped with two or more interfaces can roam across heterogeneous networks. This feature enables the devices to maintain service continuity by performing vertical handovers and to increase transmission capability by exploiting multiple physical transmission paths. However, this type of service continuity is not yet commonly provided. Previous approaches toward the provision of service continuity are limited either in their functionalities or in the scope of cross-layer information. In this paper, we analyze how cross-layer architecture provides service continuity from a broader perspective and propose Cooperative Layered Architecture (CoLA) implemented on Android system for service continuity during handover process. CoLA helps comprehensive information gathering from all layers for handover decisions, provides simple interfaces to make applications mobility-sensitive, and achieves efficient multipath transmissions across heterogeneous wireless links. Experimental results show that CoLA achieves its design goal in providing service continuity.
A cross-layer signaling and middleware platform for multi-interface mobile devices
(2007)
Shih, Yung-Chien
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Hsu, Kai-Cheng
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
This paper presents a middleware platform approach to provide Cross-layer Signaling and Network Event Notification mechanisms for network-aware applications. Because a mobile device may be equipped with multiple network interfaces to attach different network as it moves, a network-aware application running on the mobile device must react promptly to the changes of network environment. In order for the applications to detect network changes, the proposed middleware platform provides APIs for setting up network configuration and acquiring low-layer statuses. Therefore, an application can detect network changes promptly via Network Event Notification mechanism. We also use two network-aware applications, namely a Mobility Manager and a Modified Kphone, as examples to demonstrate the effectiveness of our middleware platform.
A Fair Scheme for Multi-channel Selection in Vehicular Wireless Networks
(2013-12-01)
Wang, Kuo-Lung
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Wang, Tsan-Pin
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
In recent years, the IEEE 802.11p/1609 wireless access in vehicular environments standards adopt the dedicated short-range communications multi-channel architecture for vehicular wireless networks. To utilize the multi-channel architecture, each vehicle equipped with two sets of transceivers can operate concurrently on three different channels. For example, in cluster-based multi-channel schemes, a cluster head vehicle coordinates and assigns an appropriate channel to its cluster members. However, these schemes are unsuitable for a single channel device performing on only one RF channel at a time which would waste channel resource and increase time to allocate a channel. Another approach, called LEACH-based scheme, selects channels randomly and ensures that each channel is selected once within a round in each vehicle. However, this leads to a situation that different vehicles might select the same channel in short-term duration. In this paper, we propose a multi-channel selection scheme, called minimum duration counter (MDC) scheme, which could apply to a single channel device, while utilizing the multi-channel architecture of an 802.11p/1609 network. In addition, we compare the MDC scheme with pure random (PR) and LEACH-based schemes in terms of fairness index (FI) and utilization to emphasize the fairness and to balance the traffic of multi-channel usage. Furthermore, we analyze the counter overflow probability distribution and propose solutions to the MDC scheme. Numerical results show that our scheme outperforms the PR and LEACH-based schemes in terms of multi-channel usage, traffic balancing, and fairness.
A Fast Authentication Scheme for WiMAX-WLAN Vertical Handover
(2013-07-01)
Huang, Kuei-Li
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Chi, Kuang-Hui
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Wang, Jui-Tang
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Tseng, Chien-Chao
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資訊工程學系
In view that authentication has made a significant determinant in handover delay, this paper presents a fast authentication mechanism for mobile stations roaming within a WiMAX-WLAN interconnected environment. Incorporating a key reuse design that prevents repeated transactions at a remote server, our mechanism distributes security contexts ahead of handover to a local trusted key holder which manages several sites. A target site, upon receiving a mobile station, retrieves the contexts locally for authentication purpose and thus completes handover efficiently. While employing a target prediction algorithm as an option, our mechanism distributes the contexts to target candidates as dictated, which further improves handover performance if target prediction hits and maintains its advantage even in a miss. In addition, the handover optimization design specified in WiMAX is extended to support WiFi-to-WiMAX handovers. We reason that the proposed mechanism does not compromise the system in any sense as well. Analytical and simulation results show that, despite key pre-distribution misses, our mechanism leads to marked improvement over counterpart schemes in terms of handover delay and packet loss, meeting delay-sensitive application requirements.
A mobile bandwidth-aggregation reservation scheme for NEMOs
(2008-03-01)
Wang, Jui-Tang
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Hsu, Yuan-Ying
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
A NEtwork that is MObile (NEMO) usually consists of at least one Mobile Router (MR) attached to the infrastructure to manage all external communication for of all nodes inside a NEMO. Because a NEMO moves as a whole, previous mobile ReSource reserVation Protocols have two problems in supporting quality of services (QoS) for NEMOs; that is, mobility unawareness and excessive signal overhead. In this paper, we first address these two problems and then propose a Mobile Bandwidth-Aggregation (MBA) reservation scheme to support QoS guaranteed services for NEMOs. In order to resolve these two problems, MBA makes an MR the proxy of all nodes insides a NEMO and has the MR aggregates and reserve the bandwidth required for all node inside a NEMO. Mathematical analysis and simulation results show that the proposed MBA scheme can significantly reduce the signal overhead for reservation maintenance. Furthermore we also present three hypothetic policies of tunnel reservations for NEMOs, and conduct simulation to evaluate these policies in terms of blocking probabilities and bandwidth utilizations.
A network address translation approach to the inbound session problem in private networks
(2007-02-01)
Hsieh, Ming-Deng
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Chang, Hung-Chun
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Tseng, Chien-Chao
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Wang, Tsan-Pin
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資訊工程學系
This paper proposes a Dynamic-Configurable NAT (DCNAT) approach to the inbound session problem for private networks behind NAT routers. DCNAT is a port-based NAT scheme that adopts a registration procedure for a host to register a session with a DCNAT router before originating a communication session to a host behind the DCNAT router. With the registration procedure, the DCNAT router can create NAT binding entries dynamically for address: port translation before the inbound session starts. Furthermore the dynamic creation of NAT binding entries makes DCNAT very flexible in supporting inbound accesses to a large number of services opened dynamically by the private nodes behind an NAT router. Although DCNAT requires minor modification to the originating host and the NAT router, it is highly suitable for proxy-based applications, such as web browsing, or instant message delivery.
A Preliminary Study on SPC-Crowd Pavement Indexing
(2015)
Wu, Tsung-Hsiang
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Yi, Chih-Wei
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Chan, Ching-Yao
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Chang, Ya-Lan
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Tseng, Chien-Chao
In most developed and developing countries, the maintenance of roadway pavement consumes considerable resources and represents a major item in government budget. However, due to the lack of sustainable and systematic approaches to implement long-term road pavement monitoring and assessment, the cost-effectiveness of performing such tasks is often a concern. In this paper, a crowdsourcing framework is proposed as a solution based on a smart probe car (SPC) system that utilizes mobile sensing technologies to collect environmental roadway data. Built upon the probe-vehicle system, the proposed method not only has the potential to save a significant amount of resources but also makes it possible to acquire real-time pavement information in a large scale.
A Two-Layer Hierarchical Framework for Activity Sequence Recognition by Wearable Sensors
(2016)
Chan, Guo-Jing
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Lin, Dong-Hung
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Yi, Chih-Wei
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Tseng, Chien-Chao
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資訊工程學系
As the aging population grows, the elderly care service has become an important part of the service industry in the aging population era. Activity monitoring is one of the most important services in the field of the elderly care service. In this paper, we proposed a wearable solution to provide an activity monitoring service on elders for caregivers. This service monitors restroom activities, such as washing hands, urinating and defecation. In the proposed solution, wireless motion sensors are wore on elder\'s wrist and waist to measure their body movement. The measured motion data are processed to statistical features and aggregated to cloud servers through gateways. A two-layer hierarchical framework is used for the activity recognition. In the first layer, a preliminary recognition is performed by a supervised Reduced Error Pruning (REP) Tree classifier to detect the transition of the activity. In the second layer, a Variable Order Hidden Markov Model (VOHMM) is proposed to determine the sequence of the activities. The experiment results show that the recognition accuracy is 70 percent. We developed a prototype service App to provide a life log for the recording of the activity sequence. The caregivers can make use of this information to take necessary actions accordingly.
A User Authentication Scheme Using Physiological and Behavioral Biometrics for Multitouch Devices
(2014-01-01)
Koong, Chorng-Shiuh
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Yang, Tzu-I
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
With the rapid growth of mobile network, tablets and smart phones have become sorts of keys to access personal secured services in our daily life. People use these devices to manage personal finances, shop on the Internet, and even pay at vending machines. Besides, it also helps us get connected with friends and business partners through social network applications, which were widely used as personal identifications in both real and virtual societies. However, these devices use inherently weak authentication mechanism, based upon passwords and PINs that is not changed all the time. Although forcing users to change password periodically can enhance the security level, it may also be considered annoyances for users. Biometric technologies are straightforward because of the simple authentication process. However, most of the traditional biometrics methodologies require diverse equipment to acquire biometric information, which may be expensive and not portable. This paper proposes a multibiometric user authentication scheme with both physiological and behavioral biometrics. Only simple rotations with fingers on multitouch devices are required to enhance the security level without annoyances for users. In addition, the user credential is replaceable to prevent from the privacy leakage.
Adaptive RSU re-routing under delay constraint in multi-hop vehicular networks
(2016)
Wang, Kuo-Lung
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Wang, Tsan-Pin
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
Vehicular wireless networks (VWNs) offer wireless multi-hop communications between vehicles and roadside units (RSUs). A multi-hop wireless network with carry-and-forward routing may suffer from longer delay in packet delivery. However, the applications may demand stringent delay requirement in multi-hop VWNs. Therefore, this paper proposes an adaptive RSU re-routing strategy to alter the current associated RSU to the best RSU under delay or throughput constrains for applications in multi-hop VWNs. Performance results show that the proposed strategy is able to adaptively select a suitable packet size for the trade-off between delay and throughput to satisfy the diverse requirements of applications in multi-hop VWNs.
An analysis of location record checkpointing interval for mobility database in PCS networks
(2009-11-01)
Chang, Hung-Hsin
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Chang, Ming-Feng
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
Mobility database that stores the users' location records is very important to connect calls to mobile users on personal communication networks. If the mobility database fails, calls to mobile users may not be set up in time. This paper studies failure restoration of mobility database. We study per-user location record checkpointing schemes that checkpoint a user's record into a non-volatile storage from time to time on a per-user basis. When the mobility database fails, the user location records can be restored from the backup storage. Numeric analysis has been used to choose the optimum checkpointing interval so that the overall cost is minimized. The cost function that we consider includes the cost of checkpointing a user's location record and the cost of paging a user due to an invalid location record. Our results indicate that when user registration intervals are exponentially distributed, the user record should never be checkpointed if checkpointing costs more than paging. Otherwise, if paging costs more, the user record should be always checkpointed when a user registers.
An Autoblocking Mechanism for Firewall Service
(2017-01-01)
Fu, Shan-Jung
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Hsu, Huai-Wen
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Kao, Yi-Chih
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Tsai, Shi-Chun
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Tseng, Chien-Chao
A distributed denial-of-service (DDoS) attack could cause the incoming connections per second exceeding the capacity of the firewall device and the network system might be paralyzed. By analyzing the syslog of firewall, we design an effective mechanism to block malicious source IPs automatically from the router. We have undergone a field trial on campus for two years. The collected data shows that our approach significantly reduces suspicious traffic and improve the stability of overall network service.
An end-to-end channel allocation scheme for a wireless mesh network
(2014-12-01)
Tsao, Shiao-Li
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Su, Jiun-Jang
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Huang, Kuei-Li
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Shih, Yung-Chien
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Tseng, Chien-Chao
Co-channel interference seriously influences the throughput of a wireless mesh network. This study proposes an end-to-end channel allocation scheme (EECAS) that extends the radio-frequency-slot method to minimize co-channel interference. The EECAS first separates the transmission and reception of packets into two channels. This scheme can then classify the state of each radio-frequency-slot as transmitting, receiving, interfered, free, or parity. A node that initiates a communication session with a quality of service requirement can propagate a channel allocation request along the communication path to the destination. By checking the channel state, the EECAS can determine feasible radio-frequency-slot allocations for the end-to-end path. The simulation results in this study demonstrate that the proposed approach performs well in intra-mesh and inter-mesh communications, and it outperforms previous channel allocation schemes in end-to-end throughput. Copyright (c) 2013 John Wiley & Sons, Ltd.
An integrated call agent of the converged VoIP network
(2007-05-01)
Chang, Hung-Hsin
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Hsu, Meng-Ta
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Chang, Ming-Feng
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Tseng, Chien-Chao
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資訊工程學系
The traditional circuit-switched telecommunication network and the packet-switched data network are converging to a single packet-switched network. One important application of the converged network is telephony communications, also referred to as VoIP (Voice over IP). Call signaling protocols, such as H.323, SIP and MGCP, have been developed to support VoIP communications. To enable devices using different VoIP protocols to communicate, gateways are needed to translate messages of one protocol to messages of another. In this paper, we present a simple, flexible framework for this interworking function. The framework is based on a half-call model where a call is controlled by two half-call finite state machines (FSMs), one representing the state of the caller and the other representing the state of the callee. The interworking function has been implemented such that the caller FSM of one VoIP protocol can interact with the callee FSM of any VoIP protocol. The development effort of the interworking function is minimized since only two half-call FSMs for each VoIP protocol are needed and they can be developed independently as long as the design conforms to the same interface specification. We have developed an integrated call agent (ICA) that contains the half-call FSMs of H.323, SIP and MGCP. Calls between devices using these VoIP protocols can be set up, maintained and terminated by the ICAs.
An investigation into effectiveness of different reflective learning strategies for learning operational software
(2014-03-01)
Koong, Chorng-Shiuh
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Yang, Tzu-I
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Wu, Chao-Chin
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Li, Han-Tai
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Tseng, Chien-Chao
Skill certification promotion is one of the main policies facilitated by the technological and vocational education, where application software instruction is regarded as the core curriculum to foster skill certification. With its close connection with problem-solving learning, application software instruction relies heavily on hands-on operation incorporating information technology to adequately unravel the challenges where living or working application is simulated as problem situations. According to Dewey (1963) and Edwards (1996), the process of reflection is characterized by the inference course where learners attempt to analyze and solve the problems. However, more evidence is needed to decide what reflective learning strategies are effective for students' learning. Application software operation is categorized as procedural knowledge. Repeated drills are requisite to reach the ultimate goal of spontaneous reaction without thinking. Features of CAL system offer a well-rounded environment to meet the demands. The purposes of this study were 1) to investigate how different reflective learning strategies can affect learning effectiveness of operational application software acquisition, 2) to identify effective learning strategies and to incorporate the CAL approach with instructional practices to foster learning performance. Aiming at characteristics of operational software, this study proposed operational software learning strategy theory model based on reflective learning and Adaptive Character of Thought-Rational (ACT-R) model theories. The proposed model modified the reflective learning theory and added cyclical loop into CAL to fit for operational software instruction. The CAL system is developed and incorporated into learning activities of reflective learning theory strategy model by collecting frequent operation errors made in the first-year experiment as the source drill items. This study is conducted in a two-year sequence. A total of 172 second-grade students was recruited from a vocational high school. Different reflective learning strategies, individual and group reflective learning strategy, are implemented on two experimental groups in the first year. CAL strategy is later added into the experimental groups in the second year. The results suggest that group reflective learning strategy can enhance learning effectiveness of the holistic and medium-score group students. When reflective learning strategy is incorporated with CAL, in addition to maintaining the first-year learning effectiveness, learning effectiveness of the holistic and low-score group students can be benefited by individual reflective learning strategy. Furthermore, reflective learning incorporating with CAL has greater learning effectiveness than the learning without CAL. (C) 2013 Elsevier Ltd. All rights reserved.
An IP-decoupling approach to host mobility
(2007-01-01)
Wang, Chun-Chieh
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Chi, Kuang-Hui
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
This paper presents the design, implementation, and performance evaluation of an approach to supporting host mobility in the wireless Internet. We observe that a single IP address conventionally serves dual purposes: a network-level routing directive and an endpoint identity of a certain session in transport or upper layers. Therefore, when a host affiliates with a new IP address due to movements, any pre-established active session thereupon suffers outage. Unlike prior schemes exploiting mobility agents, we propose to let a host use two IP addresses for network- and transport-layer identifications, respectively, and introduce a translation table that associates the two identities. Such an association results from querying or dynamic updates to the Domain Name System, or from direct message exchanges between two communication peers so as to optimize delivery paths. Simulation results show that our scheme outperforms counterpart Mobile IP and Mobile IPv6, in terms of communication delay, packet error rate, message space overhead, and potential packet loss during handoffs. Additionally, qualitative discussions conclude that our proposal lends itself to IPv4 and IPv6 interconnected networks, or multi-tier environment such as wireless Local Area Networks and mobile telecommunication overlay systems.