Browsing by Author "Chou, Zi-Tsan"

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Asynchronous Power Management Protocols With Minimum Duty Cycle and Maximum Adaptiveness for Multihop Ad Hoc Networks
(2013-09-01)
Chou, Zi-Tsan
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Lin, Yu-Hsiang
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Sheu, Tsang-Ling
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資訊工程學系
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Department of Computer Science
IEEE 802.11 is currently the de facto medium access control (MAC) standard for mobile ad hoc networks (MANETs). However, in a multihop MANET, 802.11 power management may completely fail if stations are out of synchronization. To fix this problem, several papers have proposed various cyclic quorum-based power management (CQPM) protocols, which, however, may also fail if stations have different schedule repetition intervals (SRIs). Hence, adaptive CQPM protocols, namely, adaptive quorum-based energy conserving (AQEC) and hyper quorum system (HQS), were proposed to overcome this drawback. However, the duty cycles of AQEC and HQS are far from optimal. In this paper, we propose the optimal fully adaptive and asynchronous (OFAA) power management protocol for a multihop MANET, which has the following attractive features: 1) By means of factor-hereditary quorum space, the OFAA protocol guarantees that two neighboring stations can discover each other in bounded time, regardless of their clock difference and individual SRIs; 2) given the length of SRI, the duty cycle of a station reaches the theoretical minimum; 3) the number of tunable SRIs of every station reaches the theoretical maximum; 4) the time complexity of OFAA neighbor maintenance is O(1); 5) a cross-layer SRI adjustment scheme is proposed such that a station can adaptively tune the values of SRI to maximize energy conservation according to flow timeliness requirements. Both theoretical analysis and simulation results demonstrate that the OFAA protocol is much more energy efficient than AQEC and HQS protocols.
Optimal and Maximized Configurable Power Saving Protocols for Corona-Based Wireless Sensor Networks
(2015-12-01)
Lin, Yu-Hsiang
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Chou, Zi-Tsan
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Yu, Chun-Wei
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Jan, Rong-Hong
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資訊工程學系
Wireless sensor networks (WSNs) are one of the most important ingredients in the Internet of Things. Thus it is vital to design a good power saving protocol, which operates at the medium access control (MAC) layer, for a WSN since sensors are generally battery-powered. On the other hand, organizing a WSN into coronas centered at the sink is a simple effective technique to achieve low-overhead routing where every sensor needs neither to broadcast beacons nor to maintain routing/neighbor tables. Hence in this paper, we propose an optimal and maximized configurable power saving protocol, named Green-MAC, for a corona-based WSN, which has the following attractive features. (i) By using the generalized Chinese remainder theorem, Green-MAC guarantees that any two sensors in the neighboring coronas can simultaneously wake up in bounded time regardless of their schedule offset as well as their respective cycle lengths. (ii) Given the cycle length, the ATF-ratio (i.e. the fraction of awake time frames in a cycle) of each sensor reaches the theoretical minimum. (iii) Under the minimum ATF-ratio constraints, the number of configurable ATF-ratios of each sensor reaches the theoretical maximum. (iv) An ATF-ratio configuration scheme is proposed for Green-MAC such that the power consumption of a WSN can be minimized while the worst event-to-sink delay requirement can be fulfilled with high probability. Both theoretical analysis and simulation results demonstrate that Green-MAC greatly outperforms existing power saving protocols for corona-based WSNs, including Q-MAC and Queen-MAC, in terms of ATF-ratio, configurability, network lifetime, delay violation ratio, and event-to-sink throughput.
Optimal Asymmetric and Maximized Adaptive Power Management Protocols for Clustered Ad Hoc Wireless Networks
(2011-12-01)
Chou, Zi-Tsan
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Lin, Yu-Hsiang
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Jan, Rong-Hong
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資訊工程學系
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Department of Computer Science
IEEE 802.11 is currently the most popular medium access control (MAC) standard for mobile ad hoc networks (MANETs). On the other hand, clustering in MANETs is a promising technique to ensure the scalability of various communication protocols. Thus, we propose an optimal asymmetric and maximized adaptive power management protocol, called OAMA, for 802.11-based clustered MANETs, which has the following attractive features. 1) Given the length of schedule repetition interval (SRI), the duty cycles of both clusterheads and members reach the theoretical minimum. 2) Under the minimum duty cycle constraints, the numbers of tunable SRIs for clusterheads and members reach the theoretical maximum. 3) By means of factor-correlative coterie-plane product, OAMA guarantees bounded-time neighbor discovery between the clusterhead and its member, and between all clusterheads, regardless of stations' individual SRIs and the schedule offset between neighboring stations. 4) The time complexity of OAMA neighbor maintenance is O(1). 5) OAMA adopts a cross-layer SRI adjustment scheme such that stations can adaptively tune the values of SRI to maximize energy conservation according to flow timeliness requirements. Both theoretical analyses and simulation results show that OAMA substantially outperforms existing power management protocols for clustered MANETs, including AQEC [2] and ACQ [14], in terms of duty cycle, adaptiveness, data delay dropped ratio, network lifetime, and end-to-end energy throughput.
Optimal Fully Adaptive Power Management Protocols for Asynchronous Multi-Hop Ad Hoc Wireless Networks
(2008)
Chou, Zi-Tsan
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Lin, Yu-Hsiang
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Jan, Rong-Hong
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資訊工程學系
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Department of Computer Science
In wireless ad hoc networks, IEEE 802.11 power management may completely fail if power-saving (PS for short) stations are out of synchronization. To fix this problem, [5]-[8] proposed various cyclic quorum-based power management (CQPM) protocols, which, however, may also completely fail if some PS stations have different schedule repetition intervals (SRIs). To conquer all these problems, we propose the OAPM protocol, which has the following attractive features. (i) By means of novel factor-hereditary quorum space techniques, OAPM ensures that two PS neighbors can discover each other in finite time regardless of their clock difference and their individual SRIs. (ii) Given the maximum value of SRI, S-max, the number of tunable SRIs for every PS station is S-max. (iii) The idle duty cycles for all SRIs are minimal. (iv) The time complexity of OAPM neighbor maintenance is constant. (v) A cross-layer SRI adjustment scheme is proposed such that a PS station can adaptively tune its SRI according to traffic QoS requirements. Primary simulation results show that OAPM achieves better energy efficiency than existing CQPM protocols.
Two-tier scheduling algorithm for uplink transmissions in IEEE 802.16 Broadband Wireless Access Systems
(2006)
Chan, Lin-Fong
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Chao, Hsi-Lu
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Chou, Zi-Tsan
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資訊工程學系
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Department of Computer Science
IEEE 802.16 Broadband Wireless Access (BWA) Systems support classes of traffic with differentiated Quality of Service (QoS). However, the detailed of how to schedule traffic are left unspecified In this paper, based on this hierarchical QoS architecture, we propose a novel two-tier scheduling strategy, called two-tier scheduling algorithm (2TSA). The first tier is category-based and the second tier is weight-based Both tiers are implemented at BSs. We evaluate the performance of 2TSA via simulation. The simulation results show that our proposed algorithm can achieve both QoS guarantee and fair bandwidth allocation.