4 wireless data networks
TRANSCRIPT
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Wireless DataNetworks
with a special emphasis on
WLAN standards
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Agenda
Why WLAN?
WMAN, WWAN, WLAN, WPAN...Bluetooth & 802.15
IEEE802.11xHiperLAN/2
HomeRFConclusions
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Why emphasis on WLANs?
The market growth:From nearly zero to about 15 million customersduring 2001From about 10 to more than 180 WLAN productsduring 2001Impressive figures in a down market!
WLANs are the hottest topic in wireless worldthese days
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WMAN
Wireless Metropolitan
Area NetworkVery high rate, point-to-point communicationsLMDS:
~30GHz carrier 155 Mbps data rate
IEEE802.16 WG
From www.lmdswireless.com
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WWAN
Wireless Wide Area NetworkCoverage : few kilometersHigh power consumptionSlow Data Rates
GSM : 9.6 KbpsIS-95 : 14.4 KbpsGPRS : 115 Kbps (theoretical)
40-50 Kbps (realized)Licensed
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WLAN
Wireles Local Area NetworkCoverage : few hundred metersData rate : tens of Mbps (depends on
distance to the Access Point)Medium to high power consumption802.11x , HiperLAN, HomeRF....
WLAN standards use unlicensed spectrumband
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WLAN
WLAN configurations (from www.cisco.com)
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WPAN
Wireless Personal Area NetworkReplace short-range cables in the offices and at
homeCoverage : ~10 meters
Very low power consumption Ad-hoc connectivity
Bluetooth, IrDA, HomeRF
IEEE802.15 WG set to make Bluetooth theWPAN standard
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Bluetooth
Ericsson initiative, but has many backers (Nokia,IBM, Intel, etc.)
Technology developed by Bluetooth SIG, a not for-profit, free membership organization
Apple and Microsoft made Bluetooth future brightclear : They announced that Bluetooth will be
inherently supported by their OSs (early 2002)Microsoft presented first Bluetooth desktop peripherals(April, 2002)
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Bluetooth
A BT chip is very cheap : ~ $5
Communication is quite securedNearly 1Mbps data rate
Supports voice and data
BT operates at unlicensed 2.4GHz spectrum
What else emits in this spectrum?Microwave ovens, light bulbs, HomeRF, 802.11b,etc.
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IEEE 802.11b
The first (in market) and most widespread
wireless networking standardUp to 11 Mbps (depends on the
distance to the AP)
The Wireless EthernetGets cheaper every day
Two major drawbacks:Weak securityHigh power consumption
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IEEE 802.11b
Security is a major issue:Most corporations wont implement WLAN in largescale if security is weak.
802.11b is protected with insufficient
WEP(Wired Equivalent Privacy) Protocol
Use of VPN and other security methods isstrongly encouraged!
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IEEE 802.11b
WECA (Wireless Ethernet Compatibility
Alliance) certifies 802.11b products with
Most major technology companies are WECAmembers
Hundreds of products certified to date
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InterferenceBluetooth and 802.11b operate at samefrequencies, do they interfere?
Yes and No. Due to different radio link accessmethods (DSSS vs. FHSS), most of the times they donot block each other.
However, no one can guarantee that interference willnot happen. This may affect real time audio/videostreams.
Solution: A Blue802
combo chip that supportsboth standards but prevents interference by notemitting at the same time! (demonstrated March,
2002)
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IEEE802.11b vs. Bluetooth
Two standards operate in same frequencyband, do they compete?
This was the way they were seen until late 2001.Ex: Intel CEO announced that the Bluetooth is dead(July, 2001) and apologized (September, 2001)
Current trend: Bluetooth and 802.11bcomplement each other!
The current trend is welcomed by the productmanufacturer companies
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IEEE 802.11b & Bluetooth
You wont build a Bluetooth only LANbecause:
It will be very expensive (remember the BTcoverage and think of how many access pointsyoull need)
Youll want to use Bluetooth for short-rangecommunications because:
802.11b is power hungry, not suitable for smallhandheld devices
BT is quite cheaper 802.11b doesnt support voice
802.11b and Bluetooth will coexist.
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IEEE802.11a
Operates at 5 GHz unlicensed spectrum
54 Mbps
MAC layer same as 802.11bPhysical layer different (OFDM)
Lower range compared to 802.11b, but experimentsshow that superior data rates are observed at alldistances
WECA will certify compatible devices with Wi-Fi5logo
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IEEE 802.11a
Power consumption three times less than802.11bFaces much less interference compared to802.11b
Not compatible with 802.11b!Mixed 802.11a&b networks possible:
Cisco Aironet 1200 - Mixed 802.11a&b access point(April, 2002)Mixed mode NICs on the way!
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IEEE 802.11x
Other Work Groups also formed:802.11i
Solve the prolonged security issues with 802.11xs
WG operations almost completed
802.11g Above 20 Mbps
Operates in 2.4GHz band
Differs from 802.11b in PHY layer : 802.11g deploysOFDM
Products expected late 2002
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HiperLAN/2
ETSI didnt approve 802.11a:
Unlicensed 5GHz spectrum is being used bysatellite operators and military, therefore, Europe
would allow a standard that has
1: Dynamic Frequency Selection
2: Transmit Power Control
None of these exist in 802.11a!
ETSIs alternative : HiperLAN
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HiperLAN/2
Same PHY layer and data rate capabilities as802.11a
Advantages of HiperLAN/2 over 802.11a:QoS
ATM based protocol not just an EthernetGreater spectrum efficiency and lower interference
Almost everyone was sure that HiperLAN/2 willprevail in Europe, but..
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HiperLAN/2HiperLAN/2 was late...
Philips announced that it wont produce HiperLAN chips
(October, 2001)Not a big surprise, maybe, as the chairman of 802.11 WG is aPhilips employee...
Intel declared that two coexisting 5GHz LAN standardswill harm both parties...
Ericsson (the main supporter) says theyre notinterested in HiperLAN anymore (December, 2001)HiperLAN is over.....
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802.11 again..
Which fast wireless standard is going to be
implemented in Europe?Not 802.11a, it lacks the two criticalrequirements....
It is 802.11h!This is simply 802.11a with Dynamic FrequencySelection and Transmit Power Control
WG specs completed already...
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HomeRF
An alternative standard that competed both
with Bluetooth and 802.11bIncorporates DECT for voice and 802.11bsCSMA/CA protocol for data
Operates in 2.4 GHz unlicensed band
Due to its physical layer, HomeRF is less
vulnerable to interference compared to 802.11bHomeRF : 2 Mbps
HomeRF2.0: 10 Mbps
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HomeRF
Some strengths of HomeRF over 802.11b:Better security
Lower power consumptionVoice capabilitesEasier setup
QoSHowever, HomeRF2.0 was late:
10 Mbps 802.11b products have already entered the
market and benefiting from economies of scale802.11b soon became cheaper than HomeRFIntel abandoned HomeRF group (March 2001) in favor of802.11b
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HomeRF
Apparent success of 802.11b and Bluetooth causedHomeRF to change strategy:
None of these standards compete, they complement each other:
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HomeRF
HomeRF still striving for market share
Currently working on a new, morecompetitive standard : HomeRF3.0Main supporter : Siemens
Currently HomeRF future doesnt look very
bright...
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Current Trends
All-in-one cellular phone chips (GSM/GPRS,Bluetooth, GPS)
WLAN-TDMA or WLAN-CDMA combo NICs
Deutsche Telecom announces plans tointegrate WLAN with WWAN (GSM, GPRS...)services
Telcos are entering the market! Be prepared fororganised, proprietary WLAN networks andcombo phone bills!
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Conclusions
IEEE sets the wireless data
standards!802.11x : Wireless LAN802.15 : Wireless PAN
802.16 : Wireless MAN
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Conclusions
Wireless data market will continue to
grow very fast
802.11x doesnt explicitly supportvoice, but there is need for it:
VoIP standards are the next hot topic