October 2012
Intermediate to advanced
160 pages
2h 49m
Chinese
Content preview from 802.11n技術手冊
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第一章
802.11n-2009 導論
我感覺到了渴望…
…對速度的渴望！
—獨行俠與呆頭鵝，捍衛戰士
對於 802.11n 的訴求可以總結為一個單詞—速度。在 1 Mbps 及 2 Mbps 無線區域網路
（Wireless LAN）的石器時代中，我們可以很慈悲地說這技術還比數位用戶迴路（DSL）
快。隨著這十年的發展，無線區域網路技術已經成熟並且廣泛被視為「連上網路的方
式」，就如同在 1990 年代中期的乙太網路（Ethernet）。在我剛開始工作時，訪客最常詢
問的是哪裡可以找到最近的乙太網路連接埠。現在，他們問的是無線區域網路的密碼。
802.11n 的速度優勢，是導致許多設備不再有乙太網路連接埠這個選項的主要原因。一
旦 802.11n 讓無線區域網路的效能與有線網路能站在同樣的基準點上，無線便成了多數
人的選擇。
歷史
802.11n 自 2002 年末誕生，並且花費了七年的時間才完成。
1
如同所有的IEEE
802.11 標準，它是從一個研究小組（Study Group）開始的。成立了高傳輸量（High
Throughput）研究小組，開始著手調查如何建構可以提供 100 Mbps 速度的 802.11 實
體層（Physical Layer），即為媒介存取層（Medium Access Control，MAC）的效能。
根據早期無線區域網路的經驗法則，MAC 層的傳輸量（Throughput）將會是傳輸速
1 關於所有的 802.11 標準，要確認其狀態的最好來源即是官方的 802.11
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