IEEE 802.11

IRIRDA (Infrared Direct Access) :

RF ,

Industrial Scientific and Medical (ISM) bands 900 MHz (cell phones)2.4 GHz (Bluetooth technology) (low speed, short range)5 GHz (Wireless LAN) = 802.11

(Mobility)(Scalability) hotspots(Flexibility) (Cost)

RF (microwaves)(Security) (encryption)/(authentication)

Q: emailA: Q:A:Q:PDAA:Q:A:

Q: CDA: Q:A:Q:5.8GHzA:

(Wireless Personal Area Networks, WPAN)(Wireless Local Area Networks, WLAN)(Wireless Wide Area Networks, WWAN)

Wireless networks: (a) piconets/wireless PANsIEEE 802.15

Wireless networks: (b) wireless LANIEEE 802.11 (WiFi)

IEEE 802.11 IEEE 1997 6 , (Physical Layer) (Data Link Layer) Wi-Fi Wireless Fidelity 802.11 Wi-Fi (Alliance)

WECA

5 GHz RF 2.4 GHz ( 802.11b/g/n) 802.11 b/g 33% 802.11a

2.4 GHz 11 Mbps 46 (150 ) / 96 (300)

2.4 GHz 54 Mbps 802.11b 802.11b (Backwards compatible with 802.11b)

2.4 GHz ( 5 GHz) 802.11g 802.11b ( 802.11a)

(Wireless client) (Access point, AP)

(Wireless Bridge) 25 miles RF

802.11 2 (Infrastructure) (Ad Hoc)Infrastructure AP (Access Point, ) AP 2 , , , , AP

(Antennas) ( (gain) ) = (Directional antenna)(Omni-directional antenna) Access Points

(Basic Service Set, BSS)AP(Service Set Identifier, SSID)SSID(32)

(Access Point, AP)(Independent Basic Service Set , IBSS)

AP, , PCMCIA , Ad Hoc

(Extended Service Set, ESS) AP ( BSS ) 10%

(BSS)(BSS)

(channels) AP AP

(Carrier Sense Multiple Access with Collision Avoidance) AP (Request to Send(RTS)) , AP Clear to Send (CTS) CTS ACK AP ACK AP ACK

(Modes) (Mixed Mode) SSID WLAN SSID SSID (Wireless Channel) (auto locate)

(STA) Access Point Windows XPWinXP(http://wlan.ncnu.edu.tw/wlanFAQ/winxp/winxp.htm)

(stand-alone software) XP ping

tune into (disable) SSID IP SSID

MAC AP () MAC

(credentials) (trustworthiness) (usernames) (passwords) WLAN

AP (Internet Caf )

AP : AP AP AP =

EAP AP(RADIUS)

Remote Authentication Dial-in User ServicesAP(username)

WEP (Wired Equivalency Protocol) WEP 64 128 bits AP WEP

WEP Wi-Fi Protected Access (WPA)WPA64 bits 256 bitsAP

WLAN: IP Address MAC Address Port Numbers

802.11b, g, n 2.4 GHz 5 GHz = 802.11a, ?/ (Total Cost of Ownership, TCO) (Site Survey) (interference)/

(SSID, usernames, passwords) SSID MAC

3 (Direct Sequence Spread Spectrum, DSSS) (Frequency Hopping Spread Spectrum, FHSS) (Infrared, IR) CSMA/CA

()2

(0 1) (Spreading Code) , , (Background Noise),

, 2.4GHz , ,

802.11 2 1 Mbps DBPSK (Differential Binary Phase Shift Keying) 2 Mbps DQPSK (Differential Quadrature Phase Shift Keying)

, , , ,

,, , , ,

, , , , GFSK (Gaussian Frequency Shift Key), 1 Mbps, 2 Mbps

, , ,

802.11 DSSS()802.11 FHSS()79 802.11a OFDM()54 Mbps802.11b HR-DSSS()125.511 Mbps6Mbps802.11g OFDM()54 Mbps

, Bluetooth SIG , , , , , , , , PDA (Personal Digital Assistant, )

Bluetooth : (a)

Bluetooth : (b)

, 1 Mbps, 3 1

, , , PDA ,

(10 ) , 100 , , , , ,

, , , , 1.5 , ,

, , , , , PDA , , ,

10 , 100 , 2.4 GHz , , IEEE 802.11, (1600 )

(Piconet) 8 (active), (Master), (Client)AS: Active SlavePS: Parked SlaveSS: Standby Slave

, , , , 2.4 GHz , ,

( 1600 ) , , , , ,

(), , , , , , ,

2.4 GHz , 1600 , , , , , ,

Piconet (a)

Piconet (b)

0111

Sniff()(AMA)Hold() AMASCOPark() AMAbeaconmaster

(Base Station, BS)(Mobile Station, MS)

(Handoff)MSC(Roaming)

(AMPS)(FDMA)

AMPSGSM(TDMA)(FDMA)(IS)-95

1900 MHz()(SMS)Internet

144 Kbps384 Kbps2 Mbps2 GHz2 MHzInternet

Internet Mobile Telephone, IMT-2000

GSM (Global System for Mobile Communications, ), (European Telecommunications Standard Institute, ETSI) 1990 , ,

, GSM 3 900 MHz 1800 MHz 1900 MHz GSM , , (Circuit Switch) , ,

GSM 9.6 Kbps, , , 1998 GSM , GPRS

GPRS (General Packet Radio Service) GPRS , GPRS GSM , ,

, GPRS , , GSM , GPRS GSM

GSM GPRS (Packet Switch) , 171.2 Kbps, 9.6 Kbps 20

(Packet), , , , , ,

, , , , GPRS 115 Kbps , GPRS , 64 Kbps , GSM

1997 6 , (Ericsson) (Nokia)(Motorola) Phone.com , , , 9 WAP (Wireless Application Protocol, )

WAP , , WAP, , , , WAP,

WAP HTTP , (, PDA ) , HTTP (Hyper Text Markup Language, HTML), WAP , (Wireless Markup Language, WML)

, , , , HTTP TCP/IP, WAP WDP (Wireless Datagram Protocol)WDP TCP/IP, WAP TCP/IP

WAP WAP WAP (WAP Gateway)WDP WAP WAP , WAP , WAP WAP WAP , WML , WAP

WAP WAP , , WAP Web , WML WAP , Web , WML , WAP

WAP GPRS , HTTP ADSL , , , ADSL, HTTP ,

OSI WAP 7 (Application Layer) 5 (Session Layer)GPRS 4 (Transport Layer) 1 (Physical Layer)