在無線通訊中 , 電力的消耗是一個很重要的問題 . 除了在硬體方面的改善 , 無線技術的通訊協定也扮演著一個重要的角色 . IEEE 802.11 wireless network針對電力的管理提出了一個相當不錯的機制 , 這種機制可以讓每一個station依據自己的電力消耗情況或通訊狀況 , 適當的調整該station的power management state為power save mode或active mode , 因此可以節省通訊裝置電力的消耗 .

在這篇論文中 , 我們提出修改IEEE 802.11 polling scheme 的機制 , 分別將polling list中power save mode stations 依照AID順序或power大小順序排列 , 使得產生的polling order會不相同 , 並透過分析和模擬結果來說明我們提出的機制可以讓power mode stations傳送更多資料或很平均的傳送資料.

In wireless communication networks, power consumption is an important issue due to the limited battery power available at the mobile stations. Power management is addressed efficiently by the IEEE 802.11 standard. In this paper, we change the polling order in the polling list of AP (Access Point) to further save the power of CF-Pollable (Contention Free) stations in power saving mode. The proposed schemes can reduce the power consumption of stations in power saving mode or have balanced opportunity of polling.

1. Introduction………………………………………………………………………..1
2. Related Work………………………………………………………………………4
2.1 IEEE 802.11 MAC Scheme…………………………………………………4
2.1.1 Distributed Coordinated Function (DCF)……………………………4
2.1.2 Point Coordination Function (PCF)………………………………….7
2.2 Polling Scheme………………………………………………………………9
2.2.1 Distributed Deficit Round Robin (DDRR)………………………… ..9
2.2.2 SuperPoll Protocol…………………………………………………..10
2.3 Energy Efficiency………………………………………………………….. 11
2.3.1 IEEE 802.11 Power Management Scheme…………………………..12
3. Our Solution for Energy Efficiency in IEEE 802.11………………………………13
3.1 針對power save mode stations所提出降低power consumption的機制…14
3.2 The comparisons between IEEE 802.11 polling scheme and our proposed schemes………………………………………………………………………17
3.2.1 IEEE 802.11 and PPS1………………………………………………..17
3.2.2 Some features for our schemes and proofs……………………………19
4. Simulations…………………………………………………………………… …..24
4.1 Simulation Environment and Parameters…………………………………….24
4.2 Simulation results…………………………………………………………….26
5. Conclusion…………………………………………………………………………32

References……………………………………………………………………………33

[1] Crow, B.P.; Widjaja, I.; Kim, L.G.; Sakai, P.T. “IEEE 802.11 Wireless Local Area Networks” , IEEE Communications Magazine, Sept. 1997, Page(s): 116 – 126.

[2] Visser, M.A.; El Zarki, M., “Voice and Data transmission over an 802.11 Wireless network”, Personal, Indoor and Mobile Radio Communications, 1995. PIMRC'95. Wireless: Merging onto the Information Superhighway., Sixth IEEE International Symposium, page(s): 648 - 652 vol.2.

[3] Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications , IEEE , 1999

[4] Ranasinghe, R.S.; Andrew, L.L.H.; Everitt, D., “Impact of polling strategy on capacity of 802.11 Based Wireless Multimedia LAN”, Networks, 1999. (ICON '99) Proceedings. IEEE International Conference, Sept. 28 - Oct. 1, 1999, page(s): 96 – 103.

[5] AURA GNZ , ANAN PHONPHOEM , “Robust SuperPoll with Chaining Protocol for IEEE802.11 Wireless LANs in Support of Multimedia Application”, Wireless Networks January 2001, Pages: 65 – 73.