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Cooperative Sensing Data Collection and Distribution with Packet Collision Avoidance in Mobile Long-Thin Networks
(2018-10-01)
Chen, Lien-Wu
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Peng, Yu-Hao
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Tseng, Yu-Chee
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Tsai, Ming-Fong
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資訊工程學系
Mobile ad hoc networks (MANETs) have gained a lot of interests in research communities for the infrastructure-less self-organizing nature. A MANET with fleet cyclists using smartphones forms a two-tier mobile long-thin network (MLTN) along a common cycling route, where the high-tier network is composed of 3G/LTE interfaces and the low-tier network is composed of IEEE 802.11 interfaces. The low-tier network may consist of several path-like networks. This work investigates cooperative sensing data collection and distribution with packet collision avoidance in a two-tier MLTN. As numbers of cyclists upload their sensing data and download global fleet information frequently, serious bandwidth and latency problems may result if all members rely on their high-tier interfaces. We designed and analyzed a cooperative framework consisting of a distributed grouping mechanism, a group merging and splitting method, and a sensing data aggregation scheme. Through cooperation between the two tiers, the proposed framework outperforms existing works by significantly reducing the 3G/LTE data transmission and the number of 3G/LTE connections.
Mini-slot scheduling for IEEE 802.16d chain and grid mesh networks
(2010-11-15)
Liang, Jia-Ming
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Wu, Ho-Cheng
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Chen, Jen-Jee
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Tseng, Yu-Chee
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資訊工程學系
This work considers the mini-slot scheduling problem in IEEE 802.16d wireless mesh networks (WMNs) An efficient mini-slot scheduling needs to take into account the transmission overhead, the scheduling complexity, and the signaling overhead to broadcast the scheduling results We are interested in chain and grid WMNs, which are the basic topologies of many applications We propose scheduling schemes that are featured by low complexity and low signaling overhead. Compared to existing works, this work contributes in developing low-cost schemes to find periodical and regular schedules that achieve near-optimal transmission latencies by balancing between transmission overhead and pipeline efficiency and that are more practical and easier to implement To minimize the transmission latency, we model the transmission latency as a function of the transmission size and the subscriber stations' traffic demands, and take the first-order derivative of the transmission size to find the minimum latency Simulation results show that our schemes significantly improve over existing works in computational complexity while maintain similar or better transmission latencies (C) 2010 Elsevier B.V All rights reserved.
Algorithms, Protocols and Future Applications of Wireless Sensor Networks
(2010-12-01)
Wang, You-Chiun
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Ohtsuki, Tomoaki
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Vasilakos, Athanasios (Thanos)
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Sabharwal, Ashutosh
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Chen, Yuh-Shyan
Energy-Balanced Dispatch of Mobile Sensors in a Hybrid Wireless Sensor Network
(2010-12-01)
Wang, You-Chiun
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Peng, Wen-Chih
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Tseng, Yu-Chee
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資訊工程學系
;
Department of Computer Science
We consider a hybrid wireless sensor network with static and mobile nodes. Static sensors monitor the environment and report events occurring in the sensing field. Mobile sensors are then dispatched to visit these event locations to conduct more advanced analysis. A big challenge is how to schedule these mobile sensors' traveling paths in an energy-balanced way so that their overall lifetime is maximized. We formulate this problem as a multiround sensor dispatch problem and show it to be NP-complete. Then, we propose a centralized and a distributed heuristics to schedule mobile sensors' traveling paths. Our heuristics allow arbitrary numbers of mobile sensors and event locations in each round and have an energy-balanced concept in mind. The centralized heuristic tries to minimize mobile sensors' moving energy while keeping their energy consumption balanced. The distributed heuristic utilizes a grid structure for event locations to bid for mobile sensors. Through simulations, we show the effectiveness of our schemes. This paper contributes in defining a more general multiround sensor dispatch problem and proposing energy-efficient solutions to it.
Discriminant Minimization Search for Large-Scale RF-Based Localization Systems
(2011-02-01)
Kuo, Sheng-Po
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Tseng, Yu-Chee
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資訊工程學系
;
Department of Computer Science
In large-scale fingerprinting localization systems, fine-grained location estimation and quick location determination are conflicting concerns. To achieve finer grained localization, we have to collect signal patterns at a larger number of training locations. However, this will incur higher computation cost during the pattern-matching process. In this paper, we propose a novel discriminant minimization search (DMS)-based localization methodology. Continuous and differentiable discriminant functions are designed to extract the spatial correlation of signal patterns at training locations. The advantages of the DMS-based methodology are threefold. First, with through slope of discriminant functions, the exhaustive pattern-matching process can be replaced by an optimization search process, which could be done by a few quick jumps. Second, the continuity of the discriminant functions helps predict signal patterns at untrained locations so as to achieve finer grained localization. Third, the large amount of training data can be compressed into some functions that can be represented by a few parameters. Therefore, the storage space required for localization can be significantly reduced. To realize this methodology, two algorithms, namely, Newton-PL and Newton-INT, are designed based on the concept of gradient descent search. Simulation and experiment studies show that our algorithms do provide finer grained localization and incur less computation cost.
Surveillance on-the-road: Vehicular tracking and reporting by V2V communications
(2014-07-04)
Chen, Lien-Wu
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Tseng, Yu-Chee
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Syue, Kun-Ze
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資訊工程學系
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Department of Computer Science
Vehicular networks have attracted a lot of attention recently. One potential application of vehicular networks is to use video cameras embedded in vehicles to support video surveillance, which we call "surveillance on-the-road". Traditional surveillance systems only rely on fixed stations on the roads to monitor road conditions. With vehicular cameras, deeper and richer road conditions may be tracked. In this paper, we study the related communication issues to support such "on-the-road" surveillance scenarios. We use monitoring and tracking suspicious vehicles (such as stolen cars) on the road through license plate recognition (LPR) as an example (our results should be applicable to other scenarios as well). We show how vehicles can work cooperatively through vehicle-to-vehicle (V2V) communications to achieve this goal. With a tracking and a reporting modules, our solution does not rely on infrastructure networks. The tracking module allows handoff of a tracking job to neighboring vehicles as necessary and report of suspicious vehicles to nearby police cars. The reporting module can help guide message flows to avoid flooding the network. Simulation results verify the message efficiency of our approach. We also show how our framework can be applied to the developing WAVE/DSRC (Wireless Access in Vehicular Environments/Dedicated Short Range Communications) standards. (C) 2014 Elsevier B.V. All rights reserved.
Guest Editorial: Networking Challenges in Cloud Computing Systems and Applications
(2013-12-01)
Wei, David S. L.
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Mukherjee, Sarit
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Naik, Kshirasagar
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Nayak, Amiya
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Tseng, Yu-Chee
Dynamic Traffic Control with Fairness and Throughput Optimization Using Vehicular Communications
(2013-09-01)
Chen, Lien-Wu
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Sharma, Pranay
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Tseng, Yu-Chee
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資訊工程學系
;
Department of Computer Science
Traffic congestion in modern cities seriously affects our living quality and environments. Inefficient traffic management leads to fuel wastage in volume of billion gallons per year. In this paper, we propose a dynamic traffic control framework using vehicular communications and fine-grained information, such as turning intentions and lane positions of vehicles, to maximize traffic flows and provide fairness among traffic flows. With vehicular communications, the traffic controller at an intersection can collect all fine-grained information before vehicles pass the intersection. Our proposed signal scheduling algorithm considers the flows at all lanes, allocates more durations of green signs to those flows with higher passing rates, and also gives turns to those with lower passing rates for fairness provision. Simulation results show that the proposed framework outperforms existing works by significantly increasing the number of vehicles passing an intersection while keeping average waiting time low for vehicles on non-arterial roads. In addition, we discuss our implementation of an Zigbee-based prototype and experiences.
Integrating SIP and IEEE 802.11e to support handoff and multi-grade QoS for VoIP-over-WLAN applications
(2011-06-01)
Chen, Jen-Jee
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Lee, Ling
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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
With the increasing popularity of WLANs and the growing demand for VoIP services, there is a need to guarantee QoS for VoIP calls while support as many calls as possible. Prior efforts focus on call admission control (CAC), but did not address the important handoff and physical rate adaptation issues caused by mobility and wireless channel variation. Assuming that VoIP calls can be supported by multi-grade QoS levels and that handoff and rate adaptation are possible, we show how to conduct CAC and resource management by integrating SIP and the QoS mechanisms of IEEE 802.11e together. When wireless resource is stringent, our resource management can dynamically adjust the resource distribution among existing calls by controlling their supporting codecs and packetization intervals. This not only takes care of calls in bad channel conditions, but also can accept more calls. Thus multi-grade QoS is achieved with decreased blocking rate for new calls and less dropping rate for handoff calls. In addition, we also show how to achieve early resumption of resources for handoff calls. Both analytical and simulation results are presented to evaluate the performance of the proposed schemes. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.
Energy-conserving data gathering by mobile mules in a spatially separated wireless sensor network
(2013-10-25)
Wu, Fang-Jing
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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
This paper considers a spatially separated wireless sensor network, which consists of a number of isolated subnetworks that could be far away from each other in distance. We address the issue of using mobile mules to collect data from these sensor nodes. In such an environment, both data-collection latency and network lifetime are critical issues. We model this problem as a bi-objective problem, called energy-constrained mule traveling salesman problem (EM-TSP), which aims at minimizing the traversal paths of mobile mules such that at least one node in each subnetwork is visited by a mule and the maximum energy consumption among all sensor nodes does not exceed a pre-defined threshold. Interestingly, the traversal problem turns out to be a generalization of the classical traveling salesman problem (TSP), an NP-complete problem. With some geometrical properties of the network, we propose some efficient heuristics for EM-TSP. We then extend our heuristics to multiple mobile mules. Extensive simulation results have been conducted, which show that our proposed solutions usually give much better solutions than most TSP-like approximations. Copyright (c) 2011 John Wiley & Sons, Ltd.

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