October 2012
Intermediate to advanced
160 pages
2h 49m
Chinese
Content preview from 802.11n技術手冊
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第八章
藉由 802.11n 標準在 2009 年批准的驅動，第二波產品浪潮到來。客戶回饋指出第一波企
業設備在全功能狀況下需要超過 802.3af 的電力預算，而業者也已經做出回應。來自晶
片組製造商的第二代 802.11n 硬體為 2×2 MIMO 的設計，並且支援兩道空間串流，移
除第三條無線電鏈路並且使用更好的晶片組製造技術，這意謂著第二代的 802.11n 企業
級設備能使終端使用者運作在類似的速度，但是功耗低很多。
企業級產品的第三波浪潮則是發生在 2011 年，它為 3×3 MIMO 的設計，並且支援三
道空間串流。當在撰寫本書時，高檔 AP 都是三串流設計。雖然不明確，但卻是有可能
的，大多數晶片組設計者將會把四串流的焦點及努力放在 802.11ac 上，也就是即將到來
的千兆位元標準。
Wi-Fi 聯盟認證（Wi-Fi Alliance Certification）
Wi-Fi 聯盟（
http://www.wi-fi.org/
）是一個由推動無線區域網路技術公司所組成的行業
協會。該聯盟最出名的是從 2000 年開始進行的 Wi-Fi CERTIFIED 互通性測試計畫。在
802.11n 以前，底層的 PHY 是很簡單的，它僅有一組核心能力和少數可選的特性。「這
個設備支援 802.11a」的聲明對所有的 802.11a 設備意謂著同一件事情，然而在 802.11n
的底層技術則是更為複雜。802.11n 設備經過 Wi-Fi 聯盟的互通性認證後，會給予
Wi-Fi
CERTIFIED ...
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