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【正文】 a candidate for worldwide standardization! 2/2/2023 14成大資訊 鄭憲宗IEEE TGa (cont.)n The specifications of the Physical Layer enpass data rates from 6 Mbit/s up to 54 Mbit/s, with 20 MHz spacing between adjacent channels. n All implementations are required to support 6, 12 and 24 Mbit/s. Optional extensions are for 9, 18, 36, 48 and 54Mbit/s. n The multirate mechanism of the MAC protocol ensures that all devices municate with each other at the best data rate in the present channel. 2/2/2023 15成大資訊 鄭憲宗IEEE TGbn The TGb is working on the extension of the 1 and 2 Mbit/s data rates in the GHz band with and 11 Mbit/s has reached a technical promise solution to improve the coexistence and interoperability characteristics between options. n The multirate mechanism warrants that the 11 Mbit/s operation can switch back to Stations that are even further could switch back to the 2 and 1 Mbit/s capabilities of the DSSS modulation. 2/2/2023 16成大資訊 鄭憲宗CSMA/CD (LAN)1. Send data if the medium is sensed “idle”2. If collides with other host(s),3. then backoff for a random number of times3. Resend data later2/2/2023 17成大資訊 鄭憲宗Hidden Terminal Problem BA Cdata data2/2/2023 18成大資訊 鄭憲宗Solution to HTPBA CRequestGrant2/2/2023 19成大資訊 鄭憲宗Detection of CollisionBA CRequest Request2/2/2023 20成大資訊 鄭憲宗BA CRequestA is Grant A is GrantDCollision Avoidance2/2/2023 21成大資訊 鄭憲宗RTS/CTS/data/ACK and NAV setting2/2/2023 22成大資訊 鄭憲宗Some IFS relationships and basic access method2/2/2023 23成大資訊 鄭憲宗Random backoff timen Backoff time = INT(CW * Random())*aSlotTimen INT(x) : 小於或等於 x的最大整數(shù)n CW(contention window parameter ) : 介於CWmin和 Cwmax間的整數(shù) , CW依序遞增的順序?yàn)?(7,15,31,63,127,255,255,255……)n Random() : 介於 0到 1間的實(shí)數(shù)n aSlotTime : 傳送器開(kāi)啟延遲 + 媒介傳遞延遲 + 媒介忙碌偵測(cè)反應(yīng)時(shí)間2/2/2023 24成大資訊 鄭憲宗An example of exponential increase of CW2/2/2023 25成大資訊 鄭憲宗Backoff procedure2/2/2023 26成大資訊 鄭憲宗Transmission of a multifragment MPDU using SIFS 2/2/2023 27成大資訊 鄭憲宗RTS/CTS with fragmented MSDU2/2/2023 28成大資訊 鄭憲宗RTS/CTS with transmitter priority and missed acknowledgment2/2/2023 29成大資訊 鄭憲宗Direct data/ACK MPDU2/2/2023 30成大資訊 鄭憲宗無(wú)線(xiàn)區(qū)域網(wǎng)路軟體技術(shù)架構(gòu)WLAN PlatformEmbedded ControlSoftwareWLAN ManagementUtilityNetworkApplicationsDSSS FHSSMedia Access ControlNetwork Driver (NDIS)Socket InterfaceMobile IP SNMPAgent Security DistributedService EMail File Transfer Remote Access Mobile DataDECTUNII or ISM band ETSI2/2/2023 31成大資訊 鄭憲宗無(wú)線(xiàn)應(yīng)用通訊協(xié)定Wireless Application Protocol(WAP)2/2/2023 32成大資訊 鄭憲宗無(wú)線(xiàn)上網(wǎng)趨勢(shì)n 日本 NTT的 DoCoMo 於 2/1999推出無(wú)線(xiàn)上網(wǎng)服務(wù)，一年內(nèi)累積 3百萬(wàn)用戶(hù)，每週增加 10萬(wàn)人n WAP Forum於 1997年成立，至 1999年 12月全世界有 200家無(wú)線(xiàn)通訊事業(yè)成為會(huì)員 (95%市場(chǎng)之相關(guān)業(yè)者投入 )n 1999年， WAP是手機(jī)使用者最熱門(mén)話(huà)題之一2/2/2023 33成大資訊 鄭憲宗無(wú)線(xiàn)上網(wǎng)趨勢(shì) (續(xù) )n 1999年在臺(tái)灣銷(xiāo)售 180萬(wàn)隻手機(jī)前兩大廠 ─ Motorola 於 2023上半年 WAP手機(jī)佔(zhàn) 40% ，下半年 100%投入； Nokia 則佔(zhàn) 30%。n 國(guó)內(nèi)
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