無線網路技術應用於802

Transcription

1 路 b g 林 立 里 s @cc.ncu.edu.tw jimchang@axp1.csie.ncu.edu.tw sheujp@csie.ncu.edu.tw 年來 路 來 WLAN 都 流 率 (Throughput) 數 WLAN 論 WLAN Ad-hoc mode Infrastructure mode 行 路 WEP 802.1x WPA WLAN RTS/CTS 都 : Ad-hoc modeinfrastructure mode RTS/CTSWPA (Wi-Fi Protected Access) 1 了 1999 年 12 了 b a, 度 11Mbps 54Mbps 2000 立 b Broadcom (Texas Instruments)(Conexant) Atheros a 2002 年 a 5GHz b 2.4GHz 不 a 度 WLAN 流 2003 年 6 IEEE() g g 了 a b OFDM PBCC 率 54M a 度 g 2.4GHz b b 更 g 流 b g WLAN 都 Throughput 數 了連 率 力 離 率 Channel 切 WLAN [4,5] b g 數 流行 率 來 論 Ad-hoc

2 Infrastructure mode b g 行 量 數 Throughput 路 WEP 802.1x Wi-Fi Alliance 行 WPA 路 Throughput 論 b/g Ad-hoc mode b/g Infrastructure mode 說 Infrastructure mode 六 RTS/CTS 論 來 IEEE 1997 年 路 了 MAC 兩 (physical layer): (frequency -hopping spread-spectrum FHSS) 列 (direct -sequence spread-spectrum DSSS) 來 陸 了 不 b 列 (HR/DSSS) a g (orthogonal frequency division multiplexing OFDM) b[1] High-Rate (HR-DSSS) Wi-Fi 2.4GHz Long Short 兩 PreambleLong Preamble Mbps 度 Short Preamble Mbps 度 g[2] 2003 年 6 度 54Mbps a 2.4GHz b b g g WLAN 流 g 了 OFDM QPSK b GHz 路 兩 :(1) 路 (Ad-Hoc Wireless LAN) 不 量 路 不 (Access Point) 類 路 (2) 路 (Infrastructure Wireless LAN) 路 (Access Point) 路 路 連 路 路 路 802.1X[3] 路 理 802.1x 路 利 路 來 802.1x Windows XP 802.1x b/g Ad-hoc mode g Throughput g b 54Mbps b 兩 b g

3 802.11g Throughput 率 Throughput 更 3Mbps Ad-Hoc mode 來 Notebook Station 兩 b/g 路 來 11b Conexant Cisco Aironet 35011g Atheros D-Link DWL G650 Conexant :() D-Link DWL-G650 (11g) Cisco Aironet350 (11b) 料 數 () ZyXEL G-10011g Cisco Aironet350 (11b) 數 () 兩 channel 流 量 11g 18Mbps 了 85% 2.7Mbps11b 5Mbps 了 50% 2.5Mbps ZyXEL G-100 來 離 論 都 Chariot4.5, Chariot4.5 Wi-Fi 來 b/g 流 率 (Throughput) GUI 數 () 降 論 Throughput (Mbps) 不 Chariot Chariot Console Endpoint: ()D-Link DWL-G650 & Cisco Aironet 350 Chariot Console 行 Microsoft Windows Chariot Console 拓 類 Endpoint 行 流行 Chariot Endpoint 利 行 行 Chariot Script 令 Endpoint Throughput (Mbps) () ZyXEL G-100 & Cisco Aironet b Barker(1 2) CCK(5.511) 兩 11g 了 11b 兩 OFDM( ) () Chariot Console GUI 11g OFDM

4 11b 不 11g 11g 11b 流 量 降 了 Protection 利 11g OFDM 裡 CCK RTS(Request To Send) 論 11g 11b 路 都 CCK CTS(Clear To Send) 料 11b RTS/CTS 不 RTS/CTS 不 了 行 11b 度來 了 11g 流 量 () D-link DWL-G650 Cisco Aironet 350 流 量 11g 11b 都 Channel 11g Protection 來 Packet 量 來 數 不理 11g 11b 都 2Mbps 行 11b 11g 來說 Protection 11g 11b 11g 11b 流 量 了 11g 良 11g 11b 流 量 不 ZyAIR G-100 (11g) Conexant Nitro mode() Nitro mode 11g 11b 說 11g 11b 11b 11g 11g 11g 11b 流 量 11b () Nitro mode 11g 數量 11g 11b 11b 11g 了 11g 流 量 () ZyAIR G-100 Cisco Aironet 350 流 量 ZyAIR G-100 Nitro mode 11g 11b Channel 11g 11b 流 量 11g 落 度 () 2.7Mbps 13.9Mbps 了 Throughput 立 11g 11b () Without Nitro mode () Enable Nitro mode b/g Infrastructure mode Infrastructure mode 11g Throughput 11g 11b 11b 降 11b/g station 不 例 Throughput Notebook Station 不 g g b 兩 g 兩 b

5 802.11g b 都 b11b Atheros D-Link DWL-G650 11g Conexant-G ZyXEL G-100Access point U_S_Robotics USR 5450 Linksys WAP 54G ( 六 ) Access point USR 5450 不 數 Station 行 g 流 率都 利 5.5Mbps Station b g 流 量 都 3.3Mbps 降了 40% 11b Station 滑 g station USR5450 Access point 不理 Frame Burst 來 11g Frame Burst 連 來 g 料 度 理 MAC protocol Data Unit(MPDU) Destination Address(DA) MAC Service Data Unit(MSDU) MPDU 連 4K byte 便 來 n 流量 g 數 Infrastructure mode b/g Access Point g 不 數 了 Throughput g USR 5450 Client 1 Client 2 Client 3 Client WAP 54G (Frame Burst=on) Client 1 Client 2 Client 3 Client Throughput (Mpbs) Throughput (Mpbs) gx gx gx gx bx bx bx bx3 ( 六 ) AP USR5450( 不 Frame burst) Throughput () Access point WAP 54G 不 數 Station 11g 流 率都 利 6Mbps 若 Station 11b 11g 流 量 5.3Mbps 數 若 Access point WAP 54G 11g 流 量 b/g 不 都 5Mbps Linksys WAP 54G 了 gx gx gx gx bx bx bx bx3 () AP WAP 54G (Frame Burst=on) Throughput 5 11b/g Infrastructure mode Wi-Fi 路 NB PDA 行 路 Wi-Fi wired equivalent privacy protocolwep WEP 易 度 不 Wi-Fi Protected Access ( WPA) WPE 來

6 802.11i Access Point 理 Station 連 WLAN b/g WEP WPA 料 料 流 率來 NB b/g Wireless Card Infrastructure mode Access Point Access Point 連 RADIUS Server WLAN Station Throughput 論 TX RX 流 量都 21Mbps WPA 了 Access Point RADIUS Server 流 量 降 降 度 16% ( ) ( ) b Access Point No WEP128WEP WPA 量 TX RX 數 數 b NO WEP128WEP 論 TX RX 流 量都 4.7Mbps WPA 了 Access Point RADIUS Server 流 量 降 4.1 降 度 12% () g Infrastructure mode TX throughput Throughput Throughput () b Infrastructure mode TX throughput () g Infrastructure mode RX throughput ()() g Access Point No WEP128WEP WPA 量 TX RX 數 數 g NO WEP128WEP Throughput () b Infrastructure mode RX throughput g RTS/CTS

7 路 Infrastructure mode CSMA/CA 來 兩 Wireless client 料 Access Point WLAN Hidden note CSMA/CA 易 狀 IEEE RTS/CTS 利 兩 g Wireless client g AP 兩 Wireless client 拉 不 離 立 Hidden note 不 度 來 量 Wireless client RTS/CTS RTS/CTS WLAN 異 Hidden note RTS/CTS Access Point ZyAIR G-3000 Infrastructure mode Hidden note WLAN 連 兩 Notebook Client PC 連 Access Point Chariot console Notebook ASUS P4 1.8G g Wireless card Conexant ZyXEL G-100 來 () ZyAIR G-100(802.11g) 路 Hidden note RTS/CTS 度 Throughput CSMA/CA 率 數連 率 降 度 () 度 400 Bytes Throughput 16.8 Mbps 度 2400 Bytes Throughput 36% 22.9 Mbps RTS/CTS WLAN RTS/CTS 49%~56% 度 400 Bytes 量 Throughput 8.3Mbp 度 2400 Bytes Throughput 12.9Mbps 說 RTS/CTS Throughput 降 利 RTS Threshold 來 料 RTS Threshold RTS/CTS 便 來 WLAN Throughput Throughput(Mbps) Throughput(Mbps) 度 () Hidden note RTS/CTS Throughput 度 () Hidden note 不 RTS/CTS Throughput

8 7 論 來 論 WLAN b g 說 WLAN card Access point 不 Ad-hoc Infrastructure mode b\g 路 WEP WPA 離 數 料 b g (Conexant) wireless card Linksys AP 說 2.7 路 AP 行 Wi-Fi WPA 降 了 16% RTS/CTS WLAN 不 Hidden Terminal RTS/CTS 了 49%~56% 若 Hidden Terminal RTS/CTS 了 135% 論 數 路 參 [1] IEEE Std b-1999, Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher-Speed Physical Layer Extension in the 2.4 GHz Band. [2] IEEE Std g-2004, Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications. Amendment 4: Further Higher Data Rate Extension in the 2.4 GHz Band. [3] IEEE Std 802.1X-2001, Local and metropolitan area networks-port-based Network Access Control. [4] Angela Doufexi, Simon Armour, Beng-Sin Lee, Andrew Nix, and David Bull, An Evaluation of the Performance of IEEE a and g Wireless Local Area Networks in a Corporate Office Environment, in the proceedings of IEEE International Conference on Communications (ICC '03), Page , May [5] Ming-Ju Ho, Jing Wang, Kwvin Shelby, and Herman Haisch, IEEE g OFDM WLAN Throughput Performance, in the proceedings of IEEE 58th Vehicular Technology Conference (VTC 2003), Page , Oct [6] Martin Heusse, Franck Rousseau, Gilles Berger-Sabatel, and Andrzej Duda, Performance Anomaly of b, in the proceedings of Twenty-Second Annual Joint Conference of the IEEE Computer and Communications Societies (Infocom 2003), Page , March [7] S. Armour, A. Doufexi, A. Nix, and D. Bull, A Study of the Impact of Frequency Selectivity on Link Adaptive Wireless LAN System, in the proceedings of IEEE 56th Vehicular Technology Conference (VTC 2002), Page , Sept [8] Gen-Li Chen, The Analysis of Data Security in Wired Equivalent Privacy Algorithm for Wireless Local Area Network, in the IEEE Communications Magazine, Page27-30, 2002.