在無線區域網路中，為使行動主機在無資料傳輸時達到省電的效能，在IEEE 802.11 DCF通訊協定中定義了省電模式(Power Saving Mode, PSM)的運作規則，處於省電模式的行動主機可事先決定在哪些Beacon Interval的ATIM Window時段該醒來，以便得知鄰居是否有交換資料的需求。然而，PSM機制對於行動主機如何選擇醒來的ATIM Window並無詳細的規劃，為使各行動主機醒來的時段能有交集，許多先前的研究[1-4]以Quorum技術為基礎，使各主機能分散式地安排其醒睡時段。然而，這些醒睡的安排並未完全將行動主機通訊特性納入考量，這些特性包括相鄰行動主機才有共同醒來時段的需求，以及相鄰兩步(two-hop) 行動主機共同醒來將可能產生傳輸上的衝撞等重要特質，此外，醒睡的安排亦應符合電量平衡的原則。為提昇省電效能並增加傳輸成功率，本論文提出一架構在Quorum系統上的醒睡安排機制，考量上述通訊特性，搭配位置資訊以分散式的方法達到電量平衡和低電量消耗的目標。根據實驗結果，本論文所提出之演算法確實可改善現有研究之缺點，大符改善電量消耗及傳輸成功率，並可達到電量平衡的目地。

IEEE 802.11 specifies a Power Saving Mode (PSM) in order to save the energy consumptions of mobile stations. Following the standard of PSM, a number of studies [1-4] further discussed the wakeup/sleep scheduling of beacon intervals based on Quorum systems so that any pair of stations has common awake intervals for data exchange. However, the existing approaches did not take into account the following two communication properties. First, only the pair of one hop neighboring stations requires common beacon interval for data exchange. Second, the awake beacon intervals of any pair of two-hop neighboring stations should be totally different in order to avoid the potential collisions occurred due to hidden terminal problem. This thesis considers the above-mentioned two communication properties and aims to develop a location-aware scheduling algorithm for scheduling the sleep/awake beacon intervals. Performance study reveals that the proposed power saving mechanism outperforms existing approaches in terms of energy consumption and throughput.

List of Contents
List of Contents	I
Lists of Figures	II
List of Tables	IV
Ｉ. Introduction	1
II. Related Work	4
III. System Model	7
3.1 Network Environment	7
3.2 Problem Statements	9
IV. Location-Aware Power Saving Mechanism	11
4.1 Location-Aware Quorum System	11
4.2 The LASP scheme	17
A. Identifying Phase	17
V. Performance Study	20
VI. Conclusion	32
VII. References	33
Appendix A. Conference Version	34
Lists of Figures
Figure 1: The illustration of beacon intervals applied in the Power Saving Mode of IEEE 802.11.	2
Figure 2:An example for illustrating the common Beacon Intervals distributively determined	4
Figure 3: The MANET N is assumed to be partitioned into regular hexagons and groups.	8
Figure 4: The length e of each cell can be evaluated by the communication range.	9
Figure 5: The arrangement of awaked Beacon Intervals for the cells of the group Gk.	13
Figure 6: The arrangement of awaked Beacon Intervals for communicating with the neighboring groups.	15
Figure 7: The available location-aware Quorum applied in the LAPS scheme.	16
Figure 8: An example to illustrate how to determine the groups which their central locations locate at the intersection of lines L1 and L2.	17
Figure 9: An example to illustrate how to determine the group and the cell where the host located.	19
Figure 10: The performance improvement of the proposed algorithm in terms of the packet loss rate	21
Figure 11: the performance comparison of the compared three algorithms in terms of average end-to-end delay.	23
Figure 12: The comparison of average energy consumption.	25
Figure 13: The comparison of three mechanisms in terms of energy efficiency.	26
Figure 14: The variation of Traffic Rate designed according to (1)	27
Figure 15: packet loss rate of the compared mechanisms in the traffic model of variable bit rate.	28
Figure 16: The energy consumption of compared mechanisms under the VBR traffic model.	29
Figure 17: The comparison of efficiency of energy consumption which is measured by the energy consumption per byte successfully transmitted.	30
List of Tables
Table 1     Parameters and their values set up in the simulation	20

[1]	IEEE Standard 802.11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications, IEEE 802.11 Std., November 1999.
[2]	Yu-Chee Tseng, Chih-Shun Hsu, and Ten-Yueng Hsieh , “Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks,” in IEEE INFOCOM 2002 Volume 1, Issue , 2002 Page(s): 200 - 209 vol.1
[3]	C. M. Chao and J. P. Sheu , “An Adaptive Quorum-Based Energy Conserving Protocol for IEEE 802.11 Ad Hoc Networks,” IEEE 	Transactions On Mobile Computing, vol. 5, pp. 560- 570 , 2006.
[4]	J.-R. Jiang, Y.-C. Tseng, C.-S. Hsu, and T.-H. Lai, “Quorum-Based Asynchronous Power-Saving Protocols for IEEE 802.11 Ad Hoc Networks,” Mobile Networking and Applications, pp. 169–181, 2005.
[5]	The Network Simulator—ns-2, http://www.isi.edu/nsnam/ns/, 2005.
[6]	C. E. Perkins and P. Bhagwat, “Highly Dynamic Destination-Sequenced Distance-Vector Routing (DSDV) for Mobile Computers,” Computer Communication.Rev., pp. 234-44, Oct. 1994.