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with a special emphasis on WLAN standards

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					Wireless Data
 Networks
 with a special emphasis on
     WLAN standards
12/23/2004   Wireless Data Networks   1
Agenda

Why WLAN?
WMAN, WWAN, WLAN, WPAN...
Bluetooth & 802.15
IEEE802.11x
HiperLAN/2
HomeRF
Conclusions

12/23/2004           Wireless Data Networks   2
             Why emphasis on WLANs?

    The market growth:
         From nearly zero to about 15 million customers
         during 2001
         From about 10 to more than 180 WLAN products
         during 2001
         Impressive figures in a down market!


    WLANs are the hottest topic in wireless world
    these days

12/23/2004               Wireless Data Networks           3
                              WMAN

    Wireless Metropolitan
    Area Network
         Very high rate, point-to-
         point communications
         LMDS:
             ~30GHz carrier
             155 Mbps data rate


         IEEE802.16 WG



                                                From www.lmdswireless.com
12/23/2004                        Wireless Data Networks                    4
                             WWAN

    Wireless Wide Area Network
         Coverage : few kilometers
         High power consumption
         Slow Data Rates
             GSM : 9.6 Kbps
             IS-95 : 14.4 Kbps
             GPRS : 115 Kbps (theoretical)
                     40-50 Kbps (realized)
         Licensed


12/23/2004                    Wireless Data Networks   5
WLAN

    Wireles Local Area Network
         Coverage : few hundred meters
         Data rate : tens of Mbps (depends on
                        distance to the Access Point)
         Medium to high power consumption
         802.11x , HiperLAN, HomeRF....


    WLAN standards use unlicensed spectrum
    band
12/23/2004                 Wireless Data Networks       6
                           WLAN




             WLAN configurations (from www.cisco.com)
12/23/2004                  Wireless Data Networks      7
                              WPAN
    Wireless Personal Area Network
         Replace short-range cables in the offices and at
         home
         Coverage : ~10 meters
         Very low power consumption
         Ad-hoc connectivity
    Bluetooth, IrDA, HomeRF
    IEEE802.15 WG set to make Bluetooth the
    WPAN standard
12/23/2004                 Wireless Data Networks           8
                           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 bright
    clear : They announced that Bluetooth will be
    inherently supported by their OSs (early 2002)
         Microsoft presented first Bluetooth desktop peripherals
         (April, 2002)

12/23/2004                    Wireless Data Networks               9
                       Bluetooth
    A BT chip is very cheap : ~ $5
    Communication is quite secured
    Nearly 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.

12/23/2004               Wireless Data Networks       10
                   IEEE 802.11b

    The first (in market) and most widespread
    wireless networking standard
    Up to 11 Mbps (depends on the
                 distance to the AP)
    The “Wireless Ethernet”
    Gets cheaper every day

    Two major drawbacks:
         Weak security
         High power consumption
12/23/2004              Wireless Data Networks   11
                      IEEE 802.11b

    Security is a major issue:
         Most corporations won’t implement WLAN in large
         scale if security is weak.

    802.11b is protected with insufficient
    WEP(Wired Equivalent Privacy) Protocol
    Use of VPN and other security methods is
    strongly encouraged!
12/23/2004                  Wireless Data Networks     12
               IEEE 802.11b

 WECA (Wireless Ethernet Compatibility
 Alliance) certifies 802.11b products with



 Most major technology companies are WECA
 members
 Hundreds of products certified to date


12/23/2004          Wireless Data Networks   13
                    Interference
Bluetooth and 802.11b operate at same
frequencies, do they interfere?
     Yes and No. Due to different radio link access
     methods (DSSS vs. FHSS), most of the times they do
     not block each other.
     However, no one can guarantee that interference will
     not happen. This may affect real time audio/video
     streams.
Solution: A Blue802® combo chip that supports
both standards but prevents interference by not
emitting at the same time! (demonstrated March,
2002)
12/23/2004              Wireless Data Networks        14
             IEEE802.11b vs. Bluetooth

    Two standards operate in same frequency
    band, 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 802.11b
             complement each other!
    The current trend is welcomed by the product
    manufacturer companies
12/23/2004                    Wireless Data Networks              15
             IEEE 802.11b & Bluetooth
    You won’t build a “Bluetooth only” LAN
    because:
         It will be very expensive (remember the BT
         coverage and think of how many access points
         you’ll need)
    You’ll want to use Bluetooth for short-range
    communications because:
         802.11b is power hungry, not suitable for small
         handheld devices
         BT is quite cheaper
         802.11b doesn’t support voice
    802.11b and Bluetooth will coexist.
12/23/2004                 Wireless Data Networks          16
                        IEEE802.11a
    Operates at 5 GHz unlicensed spectrum
    54 Mbps
    MAC layer same as 802.11b
         Physical layer different (OFDM)

    Lower range compared to 802.11b, but experiments
    show that superior data rates are observed at all
    distances
    WECA will certify compatible devices with “Wi-Fi5”
    logo
12/23/2004                   Wireless Data Networks      17
                 IEEE 802.11a
Power consumption three times less than
802.11b
Faces much less interference compared to
802.11b
Not compatible with 802.11b!
Mixed 802.11a&b networks possible:
    Cisco Aironet 1200 - Mixed 802.11a&b access point
    (April, 2002)
    Mixed mode NIC’s on the way!

12/23/2004             Wireless Data Networks       18
                        IEEE 802.11x
    Other Work Groups also formed:
         802.11i
             Solve the prolonged security issues with 802.11x’s
             WG operations almost completed
         802.11g
             Above 20 Mbps
             Operates in 2.4GHz band
             Differs from 802.11b in PHY layer : 802.11g deploys
             OFDM
             Products expected late 2002
12/23/2004                     Wireless Data Networks              19
                        HiperLAN/2
    ETSI didn’t approve 802.11a:
         Unlicensed 5GHz spectrum is being used by
         satellite 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!

    ETSI’s alternative : HiperLAN
12/23/2004                    Wireless Data Networks           20
                       HiperLAN/2
    Same PHY layer and data rate capabilities as
    802.11a
    Advantages of HiperLAN/2 over 802.11a:
         QoS
         ATM based protocol – not just an Ethernet
         Greater spectrum efficiency and lower interference



    Almost everyone was sure that HiperLAN/2 will
    prevail in Europe, but..
12/23/2004                   Wireless Data Networks           21
                      HiperLAN/2
HiperLAN/2 was late...
  Philips announced that it won’t produce HiperLAN chips
  (October, 2001)
       Not a big surprise, maybe, as the chairman of 802.11 WG is a
       Philips employee...
  Intel declared that two coexisting 5GHz LAN standards
  will harm both parties...
Ericsson (the main supporter) says they’re not
interested in HiperLAN anymore (December, 2001)
HiperLAN is over.....
12/23/2004                  Wireless Data Networks              22
802.11 again..

    Which fast wireless standard is going to be
    implemented in Europe?
         Not 802.11a, it lacks the two critical
         requirements....


         It is 802.11h!
             This is simply 802.11a with Dynamic Frequency
             Selection and Transmit Power Control
             WG specs completed already...

12/23/2004                    Wireless Data Networks         23
                        HomeRF

    An alternative standard that competed both
    with Bluetooth and 802.11b
         Incorporates DECT for voice and 802.11b’s
         CSMA/CA protocol for data
         Operates in 2.4 GHz unlicensed band
         Due to its physical layer, HomeRF is less
         vulnerable to interference compared to 802.11b
         HomeRF     : 2 Mbps
         HomeRF2.0: 10 Mbps
12/23/2004                Wireless Data Networks          24
                             HomeRF
    Some strengths of HomeRF over 802.11b:
         Better security
         Lower power consumption
         Voice capabilites
         Easier setup
         QoS
    However, HomeRF2.0 was late:
         10 Mbps 802.11b products have already entered the
         market and benefiting from economies of scale
         802.11b soon became cheaper than HomeRF
         Intel abandoned HomeRF group (March 2001) in favor of
         802.11b
12/23/2004                   Wireless Data Networks              25
                      HomeRF
Apparent success of 802.11b and Bluetooth caused
HomeRF to change strategy:
  “None of these standards compete, they complement each other”:




12/23/2004               Wireless Data Networks             26
HomeRF

    HomeRF still striving for market share
    Currently working on a new, more
    competitive standard : HomeRF3.0
    Main supporter : Siemens

    Currently HomeRF future doesn’t look very
    bright...


12/23/2004           Wireless Data Networks     27
                   Current Trends

    All-in-one cellular phone chips (GSM/GPRS,
    Bluetooth, GPS)
    WLAN-TDMA or WLAN-CDMA combo NICs
    Deutsche Telecom announces plans to
    integrate WLAN with WWAN (GSM, GPRS...)
    services
         Telcos are entering the market! Be prepared for
         organised, proprietary WLAN networks and
         combo phone bills!
12/23/2004                Wireless Data Networks           28
Conclusions

IEEE sets the wireless data
standards!
     802.11x : Wireless LAN
     802.15 : Wireless PAN
     802.16 : Wireless MAN

12/23/2004     Wireless Data Networks   29
Conclusions

Wireless data market will continue to
grow very fast

802.11x doesn’t explicitly support
voice, but there is need for it:
     VoIP standards are the next hot topic

12/23/2004          Wireless Data Networks   30

				
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posted:5/31/2011
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Description: HomeRF Working Group is led by the American Home RF Committee, was established in 1997, and its main tasks is to home users to establish interoperable voice and data communication networks. It launched HomeRF standard integrated voice and data transmission technology, the working frequency band for the 2.4GHz, the data transfer rate of 100Mbit / s, WLAN security in the main consideration in terms of access control and encryption technology.