IEEE 802.11多階隨意網路之高能源效率

Abstract

對於攜帶式裝置，能源管理是一個重要的問題。為了減少攜帶式裝置的能源消耗，我們的基本想法是每當傳輸結束時，讓節點儘快從活動狀態轉到休眠狀態。在本篇論文中，我們提出了一個IEEE 802.11多階隨意網路之高能源效率媒體存取層協定(PEMP)。許多相關的論文著重於單階隨意網路。在PEMP中，當節點試圖傳輸資料時，它把資料相關資訊(例如: 資料大小) 附載在ATIM*及ATIM-ACK*訊框內。ATIM*及ATIM-ACK*分別表示在ATIM及ATIM-ACK上附加資料相關資訊。利用上述方法，傳輸端及接收端可以告知其相鄰節點之資料相關資訊。然後依據收集來自其它節點的資訊，每節點會分別去計算自身的傳輸優先權。基於傳輸優先權，PEMP可以排列出較佳的傳輸順序。除此之外，類似於DPSM，PEMP也依據網路狀況動態地調整ATIM視窗。藉著減少在活動狀態的閒置時間及動態地調整ATIM視窗，PEMP相較於DPSM，其在能源消耗上可減少20%。本論文所提之高能源效率媒體存取層協定可適用於多階的隨意網路，使其兼顧到能源的消耗、產量及封包的延遲。

Power management is a critical issue for portable devices. To reduce power consumption of a portable device, our basic idea is to switch a node from active state to sleep state when its transmission finishes. In this thesis, we propose a power efficient MAC protocol (PEMP) for IEEE 802.11 multihop ad hoc networks. Most of related work targeted at single hop ad hoc networks. In PEMP, when a node intends to transmit data, it will piggyback a data profile, including data size, on ATIM* and ATIM-ACK*. ATIM* and ATIM-ACK* are ATIM and ATIM-ACK with a piggybacked data profile, respectively. In this way, senders and receivers can inform their neighbor nodes of the data profiles. Then, each node calculates its transmission priority according to the collected data profiles. Based on transmission priorities, PEMP can schedule a better transmission sequence. In addition, similar to DPSM [11], PEMP also adjusts the ATIM window dynamically. By decreasing the idle time in active state and adjusting the ATIM window dynamically based on network conditions, the power consumption of PEMP is 20 % less than that of DPSM. PEMP is suitable for multihop ad hoc networks and can achieve a better tradeoff between power consumption, throughput and delay.