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CU-Boulder TLEN 5520 - Wireless data networks

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A closer look at 802.11 — 1Wireless data networksMore on 802.11Martin HeusseA closer look at 802.11 — 2Channels 802.11b22MHz2412 MHz2437 MHzf2462 MHz1 6 11A closer look at 802.11 — 3802.11a!"""#!$#%&'""()'#*&!+,-)-,*".)!/)0#")1)$#2)3,/( &45)6789::;%:<<<+=>[email protected])D):<<<)!"""9),EE)@ABC4F)@[email protected]!"!"#$#%#&'()*+'+,-.#$%&'()*&*+,%&-).&*$%&/012&345&'$6((&7%&8&!'9&:$+;$&+'&*$%&'<,&)-&*$%&=>?*)?#>&*<[email protected])<@A&*+,%9&2BCD.);%''[email protected]&A%(6F9&[email protected]&CCB&A%*%;*&*+,%&GH&I&!'JK&#$%&D.)D6E6*+)@&A%(6F&'$6((&7%&.%E6.A%A&6'&7%[email protected]&[email protected];(<A%[email protected]&*$%&CCB&A%*%;*&*+,%K!"#$#%#"'/0123-,+'124'0.5.,6.'12+.221'7*0+',-7.4125.#$%&*[email protected]',+*&[email protected]&.%;%+L%&[email protected]*%@@6&D).*G'J&+,D%[email protected];%&'$6((&7%&MN&!&+-&*$%&D).*&+'&%OD)'%AK!"#$#%#%'/0123-,+'124'0.5.,6.'*7.01+,28'+.-7.01+90.'0128.#$.%%&*%,D%.6*<.%& [email protected]%'&-).& -<((&)D%.6*+)@& ;),D([email protected];%&*)& *$%&/012& 345&6.%& 'D%;+!%A&[email protected]& C(6<'%&PQ& )-RSSS&T*A&UN!KPP9& P888&SA+*+)@K&#FD%&P9& A%[email protected]%A&6'& N&"C&*)& IN&"C9& +'&A%'[email protected]*%A&-).& )-!;%&%@L+.)@,%@*'K#FD%&!9&A%[email protected]%A&6'&V!N&"C&*)&MN&"C9&[email protected]&#FD%&Q9&A%[email protected]%A&6'&VQN&"C&*)&"N&"C9&6.%&A%'[email protected]*%A&-).&[email protected]<'*.+6(%@L+.)@,%@*'K!"#$#:';<='+0123-,+'37.5,!51+,*23T<7;(6<'%'&P"KQK8KP&*$.)<E$&P"KQK8K"&A%';.+7%&*$%&*[email protected]',+*&'D%;+!;6*+)@'&6'');+6*%A&:+*$&*$%&321&'<7(6F%[email protected]&E%@%.6(9&*$%'%&6.%&'D%;+!%A&7F&D.+,+*+L%'&-.),&*$%&3WC39&[email protected]&*$%&*[email protected]',+*&321&%@*+*F&D.)L+A%'&*$%&6;*<6(,%[email protected]'&7F&:$+;$&*$%&'[email protected]('&.%X<+.%A&7F&*$%&3WC3&D.+,+*+L%'&6.%&+,D)'%A&)@*)&*$%&,%A+<,K!"#$#:#!'/0123-,+'7*>.0').6.)3#$%&,6O+,<,&6(():67(%&)<*D<*&D):%.&6;;)[email protected]&*)&0CC&.%E<(6*+)@'&+'&'$):@&[email protected]&#67(%&U8K! !!!! ! ! ! ! !!!?,890.'!!:@A?=<';BC'D0.E9.25F'5G122.)'7)12'D*0'+G.'H2,+.4'(+1+.3!"!# !"$# !%## !&!#!&%#!&##!%$#!%'#!%(#!%%#&#)*+,&#)*+,-./01)234)*54460)789::);234<=)$)>211501<)53)%##)*+,)?)%#)*+,)@A2B53C)-./01);234)D4C0 7AA01);234)D4C0!E%! !E(! !E'! !$#!!E$!%#)*+,-./01);234)D4C0%#)*+,7AA01);234)D4C0!$%!7AA01)789::);234<=)()>211501<)53)"##)*+,)?)%#)*+,)@A2B53C!"""#!$#%&'""()'#*&!+,-)-,*".)!/)0#")1)$#2)3,/( &45)6789::;%:<<<+=>[email protected])D):<<<)!"""9),EE)@ABC4F)@[email protected]!"!"#$#%#&'()*+'+,-.#$%&'()*&*+,%&-).&*$%&/012&345&'$6((&7%&8&!'9&:$+;$&+'&*$%&'<,&)-&*$%&=>?*)?#>&*<[email protected])<@A&*+,%9&2BCD.);%''[email protected]& A%(6F9& [email protected]&CCB&A%*%;*&*+,%&GH&I&!'JK&#$%&D.)D6E6*+)@&A%(6F&'$6((&7%&.%E6.A%A&6'&7%[email protected]&[email protected];(<A%[email protected]&*$%&CCB&A%*%;*&*+,%K!"#$#%#"'/0123-,+'124'0.5.,6.'12+.221'7*0+',-7.4125.#$%&*[email protected]',+*&[email protected]&.%;%+L%&[email protected]*%@@6&D).*G'J&+,D%[email protected];%&'$6((&7%&MN&!&+-&*$%&D).*&+'&%OD)'%AK!"#$#%#%'/0123-,+'124'0.5.,6.'*7.01+,28'+.-7.01+90.'0128.#$.%%&*%,D%.6*<.%&[email protected]%'& -).&-<((&)D%.6*+)@& ;),D([email protected];%&*)&*$%& /012&345&6.%& 'D%;+!%A&[email protected]&C(6<'%& PQ&)-RSSS&T*A&UN!KPP9&P888& SA+*+)@K&#FD%&P9&A%[email protected]%A&6'& N&"C&*)&IN&"C9& +'&A%'[email protected]*%A&-).&)-!;%&%@L+.)@,%@*'K#FD%&!9&A%[email protected]%A&6'&V!N&"C&*)&MN&"C9&[email protected]&#FD%&Q9&A%[email protected]%A&6'&VQN&"C&*)&"N&"C9&6.%&A%'[email protected]*%A&-).&[email protected]<'*.+6(%@L+.)@,%@*'K!"#$#:';<='+0123-,+'37.5,!51+,*23T<7;(6<'%'&P"KQK8KP&*$.)<E$&P"KQK8K"&A%';.+7%&*$%&*[email protected]',+*&'D%;+!;6*+)@'&6'');+6*%A&:+*$&*$%&321&'<7(6F%[email protected]&E%@%.6(9&*$%'%&6.%&'D%;+!%A&7F&D.+,+*+L%'&-.),&*$%&3WC39&[email protected]&*$%&*[email protected]',+*&321&%@*+*F&D.)L+A%'&*$%&6;*<6(,%[email protected]'&7F&:$+;$&*$%&'[email protected]('&.%X<+.%A&7F&*$%&3WC3&D.+,+*+L%'&6.%&+,D)'%A&)@*)&*$%&,%A+<,K!"#$#:#!'/0123-,+'7*>.0').6.)3#$%&,6O+,<,&6(():67(%&)<*D<*&D):%.&6;;)[email protected]&*)&0CC&.%E<(6*+)@'&+'&'$):@&[email protected]&#67(%&U8K! !!!! ! ! ! ! !!!?,890.'!!:@A?=<';BC'D0.E9.25F'5G122.)'7)12'D*0'+G.'H2,+.4'(+1+.3!"!# !"$# !%## !&!#!&%#!&##!%$#!%'#!%(#!%%#&#)*+,&#)*+,-./01)234)*54460)789::);234<=)$)>211501<)53)%##)*+,)?)%#)*+,)@A2B53C)-./01);234)D4C0 7AA01);234)D4C0!E%! !E(! !E'! !$#!!E$!%#)*+,-./01);234)D4C0%#)*+,7AA01);234)D4C0!$%!7AA01)789::);234<=)()>211501<)53)"##)*+,)?)%#)*+,)@A2B53CA closer look at 802.11 — 4802.11a (cont.)!"""#$%&'()*++,-+... #/001"2"34&45&!"""&#4637687&958&!3958264!53&4":;3515<=>!" :[email protected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email protected]'*,'&1490..%).'%&'088,90+)(',*'+$)'9)*+).'7.)21)*960&'()&9.%4)('%*'D%51.)'EEPBK*'0'318+%-8)'9)88'*)+:,.Q'+,-,8,[email protected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closer look at 802.11 — 5Infrastructure network planning• If the access points do not hear each other, it does not meanthe cells are disjoint!• Paving with 3 channels:• Paving with 4 channels:A closer look at 802.11 — 6Roaming• Clients need to scan other channels (maybe helped by currentAP) ← they have to leave the channel for some time. (Can alsoleave for good and then scan)✓ The client can declare that it’s going into power save mode…• Active (probe request) or passive scanning• Reassociation handshake (contains address of former AP)• Frame sent on the DS to update switch tablesA closer look at 802.11 — 7Roaming (cont.)Disassociation req.Disassociation resp.(optional)Probe Req/respReassociation req.Reassociation resp.Unicast frame, src = STA MAC addr.A closer look at 802.11 —


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