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802.11b網(wǎng)絡(luò )標準
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價(jià)格便宜的便攜式計算機、移動(dòng)電話(huà)和手持式嵌入式系統設備的日趨流行，以及Internet應用程序和電子商務(wù)的快速發(fā)展，使用戶(hù)需要隨時(shí)進(jìn)行網(wǎng)絡(luò )連接。為滿(mǎn)足這些需求，可以使用兩種方法將便攜式設備連接到網(wǎng)絡(luò )，而沒(méi)有電纜所帶來(lái)的不便。這兩種標準就是802.11b和Bluetooth。802.11b是一種11Mb/s 無(wú)線(xiàn)標準，可為筆記本電腦或桌面電腦用戶(hù)提供完全的網(wǎng)絡(luò )服務(wù)。
以往，無(wú)線(xiàn)局域網(wǎng)發(fā)展緩慢，推廣應用困難，主要是由于傳輸速率低、成本高、產(chǎn)品系列有限，且很多產(chǎn)品不能相互兼容。如以前無(wú)線(xiàn)局域網(wǎng)的速率只有1～2Mb/s，而許多應用也是根據10Mb/s以太網(wǎng)速率設計的，限制了無(wú)線(xiàn)產(chǎn)品的應用種類(lèi)。針對目前高速增長(cháng)的數據業(yè)務(wù)和多媒體業(yè)務(wù)，無(wú)線(xiàn)局域網(wǎng)取得進(jìn)展的關(guān)鍵就在于高速新標準的制定，以及基于該標準的10Mb/s甚至更高速率產(chǎn)品的出現。IEEE 802.11b從根本上改變了無(wú)線(xiàn)局域網(wǎng)的設計和應用現狀，滿(mǎn)足了人們在一定區域內實(shí)現不間斷移動(dòng)辦公的需求，為我們創(chuàng )造了一個(gè)自由的空間。
Contents
3.8 Basic service set (BSS) basic rate set..........................................................................................1
4. Abbreviations and acronyms................................................................................................................2
7.2.3.1 Beacon frame format................................................................................................................2
7.2.3.9 Probe Response frame format..................................................................................................3
7.3.1.4 Capability Information field....................................................................................................3
7.3.1.9 Status Code field......................................................................................................................5
7.3.2.2 Supported Rates element..........................................................................................................5
9.2 DCF..............................................................................................................................................5
9.6 Multirate support..........................................................................................................................6
10.3.2.2 MLME_scan.confirm.............................................................................................................6
10.3.2.2.2 Semantics of the service primitive......................................................................................7
10.3.3.1.2 Semantics of the service primitive......................................................................................8
10.3.10 Start.........................................................................................................................................8
10.3.10.1.2 Semantics of the service primitive....................................................................................9
10.4.4 PLME_DSSSTESTMODE.....................................................................................................10
18. High Rate, direct sequence spread spectrum PHY specification.......................................................11
18.1Overview....................................................................................................................................11
18.2High Rate PLCP sublayer..........................................................................................................12
18.3High Rate PLME........................................................................................................................27
18.4High Rate PMD sublayer...........................................................................................................30
Annex A (normative), Protocol implementation conformance statement (PICS) proforma.........................59
Annex C (normative), Formal description of MAC operation......................................................................64
Annex D (normative), ASN.1 encoding of the MAC and PHY MIB............................................................88
Annex F (informative), High Rate PHY/frequency-hopping interoperability...............................................89
