2 Objectives Describe the IEEE Describe the Wi-Fi Alliance Describe country code regulatory bodies such as the FCC and ETSIDescribe the family of protocolsDescribe the original protocolDescribe the b protocolDescribe the g protocolDescribe how b and g interactDescribe the a protocolDescribe the n protocolDescribe the main components of the n protocol
3 IEEE Wireless Standards The IEEEThe IEEE develops communication standards in electrical and computer sciences, engineering, and related disciplines.There are more than 1300 protocols.The committee analyzes the applications and environments in which wireless networks are used and develops standards for them.The family has more than 26 sub protocols.
4 The Wi-Fi Alliance The Wi-Fi Alliance Wi-Fi Alliance certifies interoperability between products WLAN products.The Wi-Fi Alliance was created to solve the compatibility issueProducts include a, b, g, n draft v2.0, dual-band products, and security testing.The organization provides assurance to customers of migration and integration options.Cisco is a founding member of Wi-Fi Alliance.Certified products can be found at
5 Regulatory BodiesEach country or region defines its rules about the use of the RF space, including the following rules:Which frequencies are allowed (spectrums and channels)Which transmit powers are possible (transmitters and antennae gain and EIRP)How a wave can be sent in each frequency (modulation and encoding techniques)
6 Wireless SpectrumThe 2.4-GHz ISM band ranges from 2.4 to GHz ( GHz in Japan). In this range 11 channels are allowed in the United State, 13 in Europe, and 14 in Japan.The 5-GHz ISM band ranges from to GHz.The 5-GHz ISM band overlaps with the Unlicensed NationalInformation Infrastructure (UNII) bands:– UNII-1 ranges from 5.15 to 5.25 GHz (4 channels).– UNII-2 ranges from 5.25 to 5.35 GHz (4 channels).– UNII-2 extended ranges from to GHz (up to 11 channels).– UNII-3 ranges from GHz to GHz (4 channels).
8 The IEEE 802.11 Family of Protocols Some IEEE Standard Activities802.11a — 5GHz, 54 Mb/s; ratified in 1999802.11b — 2.4 GHz, 11 Mb/s; ratified in 1999802.11d — World Mode; ratified in 2001802.11e — QoS; ratified in 2005802.11g — 2.4GHz, 54 Mb/s; ratified in 2003802.11h — DFS and TPC mechanisms; ratified in 2004802.11i — Authentication and security; ratified in 2004802.11k — Radio resource measurement enhancements (underdevelopment)802.11n — Higher throughput improvements using MIMO antennas(under development)802.11t — WPP; test methods and metrics recommendation (under802.11w — Protected management frames (under development)
10 The Original Protocolbecame a standard in July 1997, the first standard for wireless.Two RF technologies were defined: FHSS and DSSS.The standard allows 1 Mb/s and 2 Mb/s.It defined specifications for Layer 1 and Layer 2, and basic securityis defined in the 2.4-GHz ISM band.Three nonoverlapping channels is the most common deployment.
11 The 802.11b Protocol 11 Mb/s, 2.4 GHz, DSSS Ratified as standard in September 199911 U.S. channels13 ETSI channels14 Japanese channelsPower levels:– 36 dBm Effective Isotropic Radiated Power (EIRP); FCC– 20 dBm EIRP; ETSIApproved for use nearly worldwideNot recommended for new deployments
12 802.11b Speed Coverage Two different encodings: - Barker 11 - CCK Two different modulations:- DBPSK- DQPSKFour different speeds:- 1 Mb/s (Barker + DBPSK)- 2 Mb/s (Barker + DQPSK)- 5.5 Mb/s (CCK-16 + DQPSK)- 11 Mb/s (CCK DQPSK)
13 The g ProtocolStandard for higher-rate extension in the 2.4-GHz ISM spectrumSpeed up to 54 Mb/sOFDM added to DSSSBackward-compatible with b
14 802.11b/g Cell Speeds 802.11g speeds: – 54 Mb/s, 48 Mb/s – Include b data ratesClient looks for the best speed
16 802.11b and 802.11g Coexistence 802.11b presence triggers protection mode:- RTS/CTS- “CTS to self” protection“Non-ERP present” wave spreadsthroughout the network.Throughput can drop from 22 Mb/s to 8 Mb/s.
17 The 802.11 a Protocol Ratified as standard in September 1999 54 Mb/s 5 GHz (OFDM)23 U.S. channels- Dynamic Frequency Control (DFS)*- Transmitter Power Control (TPC)*19 ETSI channels (many countries)- DFS- TPC*Required by July 20th, 2007
18 802.11a Speeds Same speeds as 802.11g No 802.11b interoperability Higher frequency, which implies lower range but also less scattering
20 802.11n: State of the Protocol IEEE is developing n standard features and attributes.Wi-Fi Alliance is using n Draft 2.0 in an interim baseline.Goal is for software upgrades to meet standard compliance and minimize hardware upgrades.
21 Summary The IEEE defines the 802.11 family of protocols. The Wi-Fi Alliance ensures the interoperability of wireless devices.The local or regional regulatory bodies define what is allowed in which spectrum.The family has more than 26 protocols.The original protocol defined 1- and 2-Mb/s speeds with FHSS and DSSS.802.11b increased the speed to 11 Mb/s.802.11g increased the speed to 54 Mb/s, but still in the ISM band.802.11b devices degrade the performances of g cells.802.11a uses the same modulation and speed as g, but inthe 5-GHz band.802.11n tries to increase speed and throughput in the ISM andUNII bands.