臺灣博碩士論文加值系統

近日來，無線區域網路已經被廣泛的應用在數個場合裡，像是旅館、校園、機場等等場合，然而有限制的資源（例如：有限的頻寬與電池能源），限制了無線區域網路的應用，除此之外，若是當網路上的流量較高，或者網路上的節點較多時，網路上的資料傳輸可能會導致傳輸碰撞，這也會消耗頻寬與能源。在這篇論文中，我們提出了一個可減少傳輸碰撞與對能源使用有效率的媒體存取控制協定，稱為PEM，PEM利用動態調整傳輸電量，減少傳輸對之間的資料傳輸干擾情況，並且基於找出同時最大可傳輸對數的理由，我們在PEM中提出了一個新穎的方式來找出同時最大可傳輸的對數，為了驗證PEM的效能，我們透過數個模擬來驗證PEM的結果，相對於DPSM、DCF等協定，模擬結果顯示PEM不只可以減少電源的消耗情況，並且可以提高網路的總處理能力。

Currently, wireless local area networks (WLAN) are applied to Internet accesses in numerous circumstances such as campuses, hotels, airports, etc. However, scarce resources (e.g., limited bandwidth and battery power) significantly restrict the applications of WLANs. Besides, the network with higher traffic loads and more stations is most likely incurs collisions, and further consumes bandwidth and energy. In this paper, a distributed protocol, Power-Efficient MAC Protocol (PEM), to avoid collisions and to save energy is proposed. PEM takes advantage of a power control technique which dynamically adjusts transmission power levels for different transmission pairs to reduce the interferences among transmission pairs. Based on the concept of Maximum Independent Set (MIS), a novel heuristic scheme with the aid of interference information is proposed in PEM to provide as many simultaneous transmission pairs as possible. To verify the performance of PEM, a lot of simulations are performed in the paper. The experimental results show that with the property of spatial reuse, PEM not only reduces power consumption, but also leads to higher network throughput in comparison with three different approaches, DCF, DCS, and DPSM.

1 Introduction 5
2 Background and Related Work 11
2.1 Channel Propagation Model . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Power Saving Mechanism for IEEE 802.11 . . . . . . . . . . . . . . . 14
2.3 DPSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4 Distributed Cycle Stealing . . . . . . . . . . . . . . . . . . . . . . . . 18
3 THE POWER-EFFICIENT MAC 21
3.1 The Channel Model and the Operation of Power-E±cient MAC . . . 21
3.2 MIS (Maximum Independent Set) Algorithm . . . . . . . . . . . . . . 28
3.3 Exceptional Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4 SIMULATIONS 35
4.1 Random Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2 Gird Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.1 1-grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2.2 4-grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5 CONCLUSIONS 45

[1] IEEE Std 802.11-1999: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) speci‾cations. Institute of Electrical and Electronics
Engineers, Inc., 1999.
[2] IEEE 802.11 WaveLan PC Card - User''s Guide, pp. A-1.
[3] B. Burns and J.-P. Ebert, \Power conumption, throughput and packet er-
ror measurements of an IEEE 802.11 interface," Telecommunication Networks
Group, Technical University Berlin, Tech. Rep., 2001.
[4] C. Ware, J. Judge, J. Chicharo, and E. Dutkiewicz, \Unfairness and capture
behaviour in 802.11 adhoc networks," in Proceedings of the IEEE International
Conference on Communications (ICC), 2000, pp. 159{163.
[5] J. Chen, S.-H. G. Chan, Q. Zhang, W.-W. Zhu, and J. Chen, \PASA: Power
adaptation for starvation avoidance to deliver wireless multimedia," IEEE Jour-
nal on Selected Areas in Communications (JSAC), vol. 21, no. 10, pp. 1663{
1763, Dec 2003.
[6] D. Goodman, R. Valenzuela, K. Gayliard, and B. Ramamurthi, \Packet reser-
vation multiple access for local wireless communications," IEEE Transactions
on Communications, vol. 37, no. 8, pp. 885{890, 1989.
[7] K. Xu, M. Gerla, and S. Bae, \How e®ective is the IEEE 802.11 RTS/CTS
handshake in ad hoc networks?" in Proceedings of the IEEE Global Telecom-
munications Conference (Globecom), 2002.
[8] E.-S. Jung and N. H. Vaidya, \A power control MAC protocl for ad hoc net-
works," in Proceedings of the Annual International Conference on Mobile Com-
puting and Networking (MobiCom), 2002.
[9] P. Karn, \MACA-a new channel access method for packet radio," in Proceedings
of ARRL/CRRL Amateur Radio 9th Computer Networking Conference, 1990.
[10] T. Rappaport, Wireless Communications: Principle and Practice. Prentice
Hall, 1996.
[11] E.-S. Jung and N. H. Vaidya, \An energy e±cient MAC protocol for wireless
LANs," in Proceedings of the Twenty-First Annual Joint Conference of the
IEEE Computer and Communications Societies (INFOCOM), vol. 3, June 2002,
pp. 23{27.
[12] C. Lin and C.-Y. Liu, \Enhancing the performance of IEEE 802.11 wireless lan
by using a distributed cycle stealing," in Proceedings of the IEEE Mobile and
Wireless Communications Network (WMWC), 2002, pp. 564{568.
[13] L. Bononi, M. Conti, and L. Donatiello, \A distributed mechanism for power
saving in IEEE 802.11 wireless LANs," ACM Mobile Networks and Applications,
vol. 6, pp. 211{222, 2001.
[14] J. Monks, V. bharghvan, and W.-M. Hwu, \Transmission power contorl for
multiple access wireless packet networks," in Proceedings of the IEEE Local
Computer Networks (LCN), 2000, pp. 12{21.
[15] M. Resende, T. A. Feo, and S. Smith, \Algorithm 787: Fortran subroutines for
approximate solution of maximum independent set problems using GRASP,"
ACM Transactions on Mathematical Software (TOMS), vol. 24, 1998.