Browsing by Author "Lin, Ting-Yu"

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A Survey of Intelligent Video Surveillance Systems: History, Applications and Future
(2015-01-01)
Fan, Chung-Shuo
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Liang, Jia-Ming
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Lin, Yi-Ting
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Wu, Kun-Ru
;
Li, Kuan-Yi
With advances in wireless network infrastructure providing powerful support for surveillance video communications, it is practical to meet the needs of intelligent surveillance systems in a wide range of applications. This survey offers a comprehensive overview of state-of-the-art technologies for intelligent video surveillance systems so as to provide researchers in this field with a summary of the progress achieved to date. The evolution of surveillance systems is outlined as well. In addition, the representative technologies for environment modeling, object classification, object tracking, behavioral analysis, and database implementation are summarized. Finally, we list several detailed discussions on possible future research directions.
A Web-based Camera Dispatch System for Video Surveillance with Dynamic Requirements
(2015-01-01)
Li, Kuan-Yi
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Liang, Jia-Ming
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Fan, Chung-Shuo
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Tseng, Yu-Chee
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Lin, Yi-Ting
Video surveillance systems are commonly used to monitor environments, such as factories, shopping malls, offices, and schools, for safety and security. However, traditional closed-circuit television cameras can only capture static scenes. When unexpected events happen, such as fire accidents or stranger intrusion, the recorded video data cannot provide immediate and precise information. In this work, we design a camera dispatch system for video surveillance with pan-tilt-zoom (PTZ) cameras, which can monitor event-areas/targets real-timely and flexibly. Users can dynamically define the monitoring requirements, such as pixel-per-foot and viewing-angle of the event-areas/targets. Then, a dispatch algorithm will decide the most necessary cameras and corresponding settings to monitor the event-areas/targets immediately. The control panel is implemented as a web-based service. The demo shows that users can easily monitor potential event-areas/targets anywhere, anytime through a web browser.
A Web-based, Real-time Video Surveillance System by Leveraging PTZ Cameras
(2015)
Li, Kuan-Yi
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Liang, Jia-Ming
;
Fan, Chung-Shuo
;
Wu, Kun-Ru
;
Lin, Yi-Ting
Video surveillance systems are commonly used for environmental monitoring. Nevertheless, existing systems such as [1, 2] can only monitor scenes statically. When an accident or a fire event happens, we cannot get the critical pictures and check those situations immediately. Therefore, we propose to leverage pan-tilt-zoom (PTZ) cameras and develop a real-time surveillance system, where the PTZ cameras can rotate in a horizontal plane by panning and in a vertical plane by tilting, and adjust the focal length by zooming, so we can control these cameras dynamically for the emergent area. Especially for the accessibility, we implement this system as a web service to help users easily define the emergent area and preview the video of cameras remotely. Specifically, our system is composed of multiple PTZ cameras and a web server, as shown in Fig. 1. The PTZ cameras are with fixed positions and can be controlled to pan, tilt, and zoom remotely by the web server. The web server maintains a website to provide the real-time surveillance service, consisting of two procedures: area setting and video displaying. The area setting is for users to define the monitored area, including the range and location of the monitored area. Then, all the cameras will be dispatched and face to the center of the monitored area. Finally, the video displaying procedure will show the monitoring results, including the video streams and the rotation parameters of the dispatched cameras. Fig. 2 shows the control panel of the implemented prototype, where there are two PTZ cameras deployed in the monitoring environment. On this panel, the left part is for video displaying and the right part is for the monitored area setting. More specifically, for the right part, the upper side is the floor plan of the monitoring environment which users can define the location of the emergent area by clicking on. On the lower left side, users can further specify the details of the area, such as its length and width. After setting, the monitored area will be marked as the red-dotted rectangle on the floor plan. Finally, the monitoring results, such as the coverage ratio of the monitored area and the rotation parameters of the cameras, will be shown on the lower central side. Note that the system also allows users to control the cameras manually on the lower right side.
Applying Genetic Algorithms for Multiradio Wireless Mesh Network Planning
(2012-06-01)
Lin, Ting-Yu
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Hsieh, Kai-Chiuan
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Huang, Hsin-Chun
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電機資訊學士班
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Undergraduate Honors Program of Electrical Engineering and Computer Science
Two main issues that are involved in the performance of multichannel multiradio wireless mesh networks (WMNs) are channel assignment (CA) and multichannel routing (MCR). The joint CA and MCR problem has been proven to be NP-hard. In this paper, we propose to apply genetic algorithms for the CA problem and tackle MCR using linear-programming techniques. Because CA and MCR tend to interact with each other, to reflect such an interplay property, we evaluate the fitness value of a chromosome (certain CA configuration) in our genetic algorithms (GAs) by computing the linear objective function. Therefore, we successfully decouple the two problems and obtain an optimized CA configuration with a corresponding MCR schedule in polynomial time at the WMN planning stage. We demonstrate the detailed genetic evolution processes for three-WMNs with different deployment constraints, which serves as a useful guideline on customizing WMNs under various requirements. Simulation results show that the proposed approach effectively increases the network capacity.
ARC: Joint Adaptation of Link Rate and Contention Window for IEEE 802.11 Multi-rate Wireless Networks
(2009)
Li, An-Chih
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Lin, Ting-Yu
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Tsai, Ching-Yi
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電信工程研究所
;
Institute of Communications Engineering
IEEE 802.11 wireless network supports multiple link rates at the physical layer. Each link rate is associated with a certain required Signal-to-Interference-and-Noise Ratio (SINH) threshold for successfully decoding received packets. Suppose constant noise and no power adjustment strategy exists, apparently SINR is solely affected by the accumulated interference power level I. The method of selecting an appropriate link rate for transmitting/retransmitting packets is generally known as the link adaptation mechanism. Traditional link adaptation approaches try to reduce the transmit rate (hence lower SINR? threshold is required) on transmission failures (potentially due to the increased denominator I of SINR), whereas upgrade the transmit rate (hence higher SINR threshold is required) on successful transmissions (potentially due to the decreased denominator I of SINR). The accumulated interference power level I in some sense indicates the medium congestion status. In 802.11, on transmission failures, the DCF performs a binary exponential backoff mechanism to discourage channel access attempts, hoping to reduce congestion. When traditional link adaptation is applied, both rate reduction and binary backoff represent double penalties for this wireless link, which may cause overly conservative transmission attempts. On the other hand, once transmission succeeds, 802.11 DCF resets the backoff contention window to the minimum value to encourage channel access attempts. At the same time, traditional link adaptation may also decide to increase the data rate, which leads to overly aggressive transmission attempts. We observe this improper interaction of link rate and backoff mechanism that harms the 802.11 system performance, due to separate consideration of those two parameters. In this paper, rather than independently dealing with the two parameters, we propose to perform link adaptations by firstly considering if a proper backoff window has been reached. Specifically, if the medium congestion level I can be reduced by imposing a larger backoff window on transmissions, then there may be no need to decrease the link rate, given SINR can be sustained. Conversely, if there is extra interference that may be tolerated in 1, a smaller backoff window can be used to encourage more transmission activities while keeping the required SINR. In particular, a joint Adaptation of link Rate and backoff Contention window, abbreviated as ARC, is devised. Our ARC protocol first estimates the optimal contention window (optCW) based on Call's approximation methods. On transmission successes (failures), the current contention window size cw(p) should be compared with optCW. If cw(p) > optCW (cw(p) < optCW), then cw(p), is decreased (increased) to perform more aggressive (conservative) transmission attempts while leaving the link rate R unchanged. Otherwise, R. is upgraded (reduced) to the next higher (lower) rate. One nice property of ARC is the ability to intelligently maintain link stability, avoiding unnecessary rate fluctuations. Simulation results show that the proposed ARC protocol outperforms several traditional link adaptation mechanisms. We also propose an analytic Markov chain model on ARC operations for performance validation.
CFPP: Collision-free Path Planning for Wireless Mobile Sensors Deployment
(2015)
Lin, Ting-Yu
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Santoso, Hendro Agus
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Lin, Chung-An
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Wang, Gui-Liu
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電機學院
With the growing popularity of wireless mobile sensors, automated sensors deployment in a smart sensing environment has become practical and feasible. Once the deployment algorithm determines moving destinations (goals) for all sensors, however, the problem of how to schedule collision-free moving paths to reach the goals safely remains largely unaddressed in the wireless sensor networking (WSN) literature. In this paper, we propose a collision-free path planning (CFPP) mechanism, based on geometric formulations and batched movements, to address the sensors deployment problem. Our proposed CFPP mechanism ensures 100% sensors goal reachability, which is critical for most WSN monitoring applications that require sufficient sensing coverage to operate correctly. Performance results show that our CFPP outperforms other existing path-planning mechanisms in terms of computation latency, energy consumption, and sensors reachability (goals reaching success probability).
Channel-Hopping Scheme and Channel-Diverse Routing in Static Multi-Radio Multi-Hop Wireless Networks
(2015-01-01)
Lin, Ting-Yu
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Wu, Kun-Ru
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Yin, Guang-Chuen
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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 modern wireless networks with multiple orthogonal (non-overlapping) channels available, one essential performance topic is how to effectively exploit channel diversity to enable parallel communications. Generally, having a radio interface hop through all available channels produces better spectrum diversity than binding it permanently to one channel, at the cost of channel switching delays and potentially compromised network connectivity. Moreover, multi-hop communications become challenging due to the lack of a common rendezvous for discovering routes and the difficulty of relaying packets from hop to hop. In this paper, we propose a multi-radio channel-hopping scheme (CHS) that preserves network connectivity. We prove that less than three radios are required by CHS in order to achieve good channel overlapping in widespread IEEE 802.11-based wireless systems. Corresponding channel-diverse routing (CDR) protocol is devised to realize efficient multi-hop communications. Simulation results demonstrate that the proposed CDR outperforms other strategies in static IEEE 802.11a multi-hop networking environments.
EARC: Enhanced Adaptation of Link Rate and Contention Window for IEEE 802.11 Multi-Rate Wireless Networks
(2012-09-01)
Lin, Ting-Yu
;
Tsai, Ching-Yi
;
Wu, Kun-Ru
;
傳播研究所
;
Institute of Communication Studies
IEEE 802.11 wireless network supports multiple link rates at the physical layer. Each link rate is associated with a certain required Signal-to-Interference-and-Noise Ratio (SINR) threshold for successfully decoding received packets. On transmission failures, the 802.11 DCF performs a binary exponential backoff mechanism to discourage channel access attempts, hoping to reduce congestion. When traditional link adaptation is applied, both rate reduction and binary backoff represent double penalties for this wireless link, which may cause overly conservative transmission attempts. On the other hand, once transmission succeeds, 802.11 DCF resets the backoff contention window to the minimum value to encourage channel access attempts. At the same time, traditional link adaptation may also decide to increase the data rate, which leads to overly aggressive transmission attempts. We observe this improper interaction of link rate and backoff mechanism that harms the 802.11 system performance, due to separate consideration of those two parameters. In this paper, we propose to jointly adapt the rate and backoff parameters. Specifically, an Enhanced Adaptation of link Rate and Contention window, abbreviated as EARC, is devised. EARC is a closed-loop (receiver-assisted) link rate adaptation protocol that jointly considers the backoff mechanism. With only one extra byte carried by the DATA packet, EARC incurs little controlling overhead despite its receiver-assisted nature. Moreover, since SINR information commonly utilized by receiver-assisted protocols is not precisely supported in real devices, we introduce a rate selection reference (RSR) table empirically derived by constantly monitoring the environmental energy level and reception behavior. The RSR table then guides the receiver to select the best sustainable rate for the transmitter. Simulation results demonstrate the RSR table is a practical option for making the rate decision, and the proposed EARC approach is effective in maintaining high system throughput, compared to other link adaptation algorithms.
Enhanced Deployment Algorithms for Heterogeneous Directional Mobile Sensors in a Bounded Monitoring Area
(2017-03-01)
Lin, Ting-Yu
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Santoso, Hendro Agus
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Wu, Kun-Ru
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Wang, Gui-Liu
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電機工程學系
Good deployment of sensors empowers the network with effective monitoring ability. Different from omnidirectional sensors, the coverage region of a directional sensor is determined by not only the sensing radius (distance), but also its sensing orientation and spread angle. Heterogeneous sensing distances and spread angles are likely to exist among directional sensors, to which we refer as heterogeneous directional sensors. In this paper, we target on a bounded monitoring area and deal with heterogeneous directional sensors equipped with locomotion and rotation facilities to enable the sensors self-deployment. Two Enhanced Deployment Algorithms, EDA-I and EDA-II, are proposed to achieve high sensing coverage ratio in the monitored field. EDA-I leverages the concept of virtual forces (for sensors movements) and virtual boundary torques (for sensors rotations), whereas EDA-II combines Voronoi diagram directed movements and boundary torques guided rotations. EDA-I computations can be centralized or distributed that differ in required energy and execution time, whereas EDA-II only allows centralized calculations. Our EDA-II outperforms EDA-I in centralized operations, while EDA-I can be adapted into a distributed deployment algorithm without requiring global information and still achieves comparably good coverage performance to its centralized version. To the best of our knowledge, this is perhaps the first work to employ movements followed by rotations for sensors self-deployment. Performance results demonstrate that our enhanced deployment mechanisms are capable of providing desirable surveillance level, while consuming moderate moving and rotating energy under reasonable execution time.
Global Sensor Deployment and Local Coverage-Aware Recovery Schemes for Smart Environments
(2015-07-01)
Lin, Ting-Yu
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Santoso, Hendro Agus
;
Wu, Kun-Ru
;
電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
One critical issue, for a wireless sensor network (WSN) to operate successfully, is to provide sufficient sensing coverage. Define the smart sensing environment as a sensing system with the capability to sense the environment and respond properly in an automated manner. In this paper, we target on smart sensing environments and deal with heterogeneous sensors (here sensor heterogeneity is defined as sensors having different sensing ranges) equipped with actuation facilities to assist in the sensor self-deployment. A coverage-aware sensor automation (CASA) protocol is proposed to realize an automated smart monitoring network. Two centralized algorithms are included in the CASA protocol suite: enhanced virtual forces algorithm with boundary forces (EVFA-B) and sensor self-organizing algorithm (SSOA). Unlike most previous works that tackle the deployment problem only partially, we intend to address the problem from both global deployment (EVFA-B) and local repairing (SSOA) perspectives. The EVFA-B protocol exerts weighted attractive and repulsive forces on each sensor based on predefined distance thresholds. Resultant forces then guide the sensors to their suitable positions with the objective of enhancing the sensing coverage (after a possibly random placement of sensors). Furthermore, in the presence of sensor energy depletions and/or unexpected failures, our SSOA algorithm is activated to perform local repair by repositioning sensors around the sensing void (uncovered area). This capability of local recovery is advantageous in terms of saving the communication and moving energies. Performance of the proposed sensor deployment strategies is evaluated in terms of surveillance coverage, monitoring density, network self-healing competence, and moving energy consumption. We also implement our CASA protocol suite in a real-life monitoring network (MoNet) to demonstrate the protocol feasibility and validate the MoNet detection capability of emergency events.
Heterogeneous Directional Sensors Self-Deployment Problem in a Bounded Monitoring Area
(2011)
Panditharathne, Charka
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Lin, Ting-Yu
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Chen, Kuan-Hua
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電信工程研究所
;
Institute of Communications Engineering
Good deployment of sensors empowers the network with effective monitoring ability. Different from omnidirectional sensors, the coverage region of a directional sensor is determined by not only the sensing radius (distance), but also its sensing orientation and spread angle. Heterogeneous sensing distances and spread angles are likely to exist among directional sensors, to which we refer as heterogeneous directional sensors. In this paper, we target on a bounded monitoring area and deal with heterogeneous directional sensors equipped with locomotion and rotation facilities to enable the sensors self-deployment. Our base and optimized deployment algorithms are proposed to achieve high sensing coverage ratio in the monitored field. These algorithms leverage the concept of virtual forces (for sensors movements) and virtual boundary torques (for sensors rotations). Performance results demonstrate that our optimized deployment mechanism is capable of providing desirable surveillance level, while consuming moderate moving and rotating energy.
Joint Adaptation of IEEE 802.11 Link Rate and Backoff Parameters: Prototyping Validation
(2015-01-01)
Wu, Kun-Ru
;
Lin, Ting-Yu
;
電信工程研究所
;
Institute of Communications Engineering
In IEEE 802.11, DCF performs a binary exponential backoff mechanism to control channel access attempts, in order to reduce congestion. When transmission fails, both binary exponential backoff and rate reduction are performed, which may induce overly conservative transmission attempts. On the other hand, once transmission succeeds, rate adaptation may decide to increase the data rate and DCF resets the contention window to minimum value, which results in overly aggressive transmission attempts. Motivated by this, we propose a mechanism entitled Enhanced Adaptation of link Rate and Contention window, abbreviated as EARC. EARC is a receiver-assisted link rate adaptation protocol that jointly considers the backoff mechanism. We implement EARC in a real-life testbed to observe its performance. Empirical results validate that EARC enhances system throughput by judiciously adapting to both the link rate and backoff parameters.
More on the one-dimensional sliding-coin puzzle
(2014-01-10)
Lin, Ting-Yu
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Tsai, Shi-Chun
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Tsai, Wen-Nung
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Tsay, Jong-Chuang
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資訊工程學系
Consider a line of n nickels and n pennies with all nickels arranged to the left of all pennies, where n >= 3. The puzzle asks the player to rearrange the coins such that nickels and pennies alternate in the line. In each move, the player is allowed to slide k adjacent coins to hew positions without rotating. We first prove that for any integer k >= 2 it takes at least n moves to achieve the goal. A well-known optimal solution for the case k = 2 matches the lower bound. We also give optimal solutions for the case k = 3. (C) 2013 Elsevier B.V. All rights reserved.
Resource planning and packet forwarding for next-generation multi-hop wireless mesh networks
(2007)
Lin, Ting-Yu
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Fan, Kang-Lun
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電信工程研究所
;
Institute of Communications Engineering
Most earlier works in the area of wireless mesh network assume a single interface being equipped in each node. In this paper, we consider the next-generation wireless mesh networks in which each node may be equipped with multiple radio interfaces, each capable of running in one of several modes, one of several channels, and each capable of supporting multiple modulations. For example, from off-the-shelf components, one can easily construct a mesh node with multiple IEEE 802.11a/b/g radio interfaces. Our goal is to address the resource planning and packet forwarding issues in such an environment. The proposed methodology is based on linear programming with network flow principles and radio channel access/interference models. Given a network topology, traffic requirements, and gateway capacities, we show how to allocate network interface cards and their channels to fully utilize channel bandwidths. The results can be used by a wireless Internet service provider to plan their networks under a hardware constraint so as to maximize their profits. To the best of our knowledge, this is the first work addressing resource planning in a wireless mesh network. Our numerical results show significant improvement in terms of aggregate network throughput with moderate network-layer fairness.
Synergizing Wireless Communication Technologies to Improve Internet Downloading Experiences
(2014-11-01)
Lin, Ting-Yu
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Huang, Tai-Yi
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Hsu, Chia-Fu
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傳播研究所
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電機資訊學士班
Considering downloading traffic from the internet, in this paper, we propose a synergized framework (SF), consisting of heterogeneous wireless communication technologies, multi-mode (multi-interface) mobile, and fixed wireless hosts capable of operating over multiple orthogonal (non-overlapping) radio channels, to realize better downloading experiences for users via cooperation between different wireless technologies. An SyNerGized (SNG) routing protocol is devised to enable the proposed framework. Given perceived network information, SNG performs computations based on linear formulations and obtains an optimized route for packet delivery. To adapt to network dynamics, a reactive version of SNG, entitled Reactive SyNerGized (RSNG) routing protocol, is proposed to alleviate the network from constantly keeping track of link capacities within a certain scope of neighborhood. Since the downloading throughput may be bounded by either the internet gateway capacity lambda(gw) or ad hoc throughput lambda(ah), RSNG judiciously propagates Route REQuest (RREQ) until the downloading throughput is bounded by lambda(ah) over the ad hoc domain, effectively eliminating unnecessary RREQ flooding. Our main objective is to improve achieved user downloading throughput via the cooperative (synergized) communication model and its corresponding routing mechanisms. Simulation results demonstrate the benefits brought by the unified architecture and corroborate the efficacy of the proposed routing techniques.