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IEEE Orange County Computer Society Joint Meeting with IEEE OC ComSig Chapter Wireless LAN Instrumentation, Scientific, Medical Band

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Title: IEEE Orange County Computer Society Joint Meeting with IEEE OC ComSig Chapter Wireless LAN Instrumentation, Scientific, Medical Band


1
IEEE Orange County Computer Society Joint
Meeting with IEEE OC ComSig ChapterWireless
LANInstrumentation, Scientific, Medical Band
  • Dwight Borses
  • MTS, Field Applications Engineering
  • National Semiconductor, Irvine,CA
  • Feb 25, 2002

2
  • The IEEE ("eye-triple-E") The Institute of
    Electrical and Electronics Engineers, Inc., helps
    advance global prosperity by promoting the
    engineering process of creating, developing,
    integrating, sharing, and applying knowledge
    about electrical and information technologies and
    sciences for the benefit of humanity and the
    profession.
  • Local volunteers needed!

3
Points to Ponder
  • Standards - so many to choose from
  • Cellular/PCS - both a competitor and a complement
    to WLAN
  • DECT up-banded applications for proprietary
    applications
  • UWB yet another contender
  • FSO Light based wireless

4
Wireless Technologies Short Distance
5
802.11 InfraredA real standard that sort of died
6
Wireless Technologies Long Distance
7
Data Migration Path to 3G WWAN
3G Fixed access at 2Mbps
2 M 384 K 144 K 64 K 14.4 K 9.6 K
3G Phase II IS-2000 Rel A (3XRTT) Packet Data /
Voice / Video
3G Phase I IS-2000 Rel 0 (1XRTT) Packet Data
Subscriber Data Rate
2.5G IS-95B Packet Data
2G IS-95-A Circuit Switched QNC
1G Analogue Cellular
1999 2000 2001 2002 2003 2004 2005 2006
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11
2.4GHz ISM Band
12
ISM Band Inhabitants (Besides 802.11) Frequency
Modulation Specs
13
Comparing Different WLAN Technologies
14
5 GHz Unlicensed National Information
Infrastructure
15
IEEE 802 Framework
16
802.11 StandardsOverview
IEEE 802.11
802.11a
802.11b
802.11i
802.11h
802.11d
802.11e
802.11f
802.11g
17
802.11 Standards
  • Original 802.11, circa 1999
  • FHSS, DSSS, IR
  • 1 2 Mbps
  • Wired Equivalent Privacy (WEP)
  • SNMP v2 for remote management
  • 802.11b (shortly after 802.11)
  • DSSS
  • 1, 2, 5.5 11 Mbps, Complementary Code Keying
    (CCK)

18
802.11 Standards
  • 802.11a (Approved same time as .11b)
  • 6, 9, 12, 18, 24, 36, 48, 54 Mbps
  • Only 6, 12, 24 Mbps support is mandatory
  • 5 GHz UNII band (not universally free)

19
802.11 Standards
  • 802.11c (completed, subsumed into d)
  • Bridge operation
  • 802.11d (ongoing)
  • Specs for other regulatory domains
  • 802.11e (ongoing)
  • QoS (Security moved to 802.11i (May 2001))
  • 802.11f (ongoing)
  • Inter Access Point interoperability

20
802.11 Standards
  • 802.11g (ongoing)
  • High-speed extension to 802.11b, gt 20Mbps
  • Just approved!
  • 802.11h (ongoing)
  • improvement to 802.11a, w.r.t. power and spectrum
    management
  • 802.11i (ongoing)
  • Security enhancements

21
Wireless Data Standards Technology Comparison
22
PANs, LANs, and Bluetooth
23
Full Range of Wireless LANs
24
Data Rates and Range by Technology
25
802.11 Infrastructure Architecture
26
802.11 - Layers and Functions
27
Binary Phase Shift KeyingQuadrature Phase Shift
Keying
28
Quadrature Modulation
29
Quadrature Amplitude Modulatoion
30
IEEE 802.11 Direct Sequence Spread Spectrum DSSS
31
Frequency Hopping Spread Spectrum (FHSS)
  • Transmitted signal is spread over a wide range
    of frequencies (ISM 2.4-2.4835 GHz)
  • Transmission hops 8 to 30 times per second

32
Complementary Code Keying
  • This sequence 1 has 4 pairs of like elements with
    a separation of 1 and 3 pairs of unlike elements
    with a separation of 1

33
Complementary Code Keying
  • This sequence has 4 pairs of unlike elements with
    separation of 1 and 3 pairs of like elements.

34
802.11 Modulation Set
35
Binary Phase Shift Keying
36
IEEE 802.11a OFDM
37
IEEE 802.11 DSSS
38
CSMA/CD
  • CSMA/CD
  • Carrier Sense, Multiple Access/Collision
    Detection
  • For wire communication
  • No control BEFORE transmission
  • Generates collisions
  • Collision Detection
  • How?

39
CSMA/CA
  • CSMA/CA
  • Carrier Sense, Multiple Access/Collision
    Avoidance
  • For wireless communication
  • Collision avoidance BEFORE transmission
  • Pre-avoidance of collision
  • Why avoidance on wireless?

40
Collision Detection On Wireless?
  • Difference on energy/power for transmit and
    receive
  • At maximum, transmission power is a million times
    larger than receiving
  • Very hard to detect because of this difference
  • Energy often matter on wireless environment
  • Portable devices/terminals with batteries

41
Backoff
  • Decrease the possibility of contention/collision
  • Backoff window
  • Time to wait ot avoid collision
  • Random backoff
  • Use random length of time to wait

42
IFS Inter Frame Spacing
  • Defined length of time for control
  • To assure the control of multiple access
  • DIFS Distributed Inter Frame Spacing
  • PIFS Point Inter Frame Spacing
  • SIFS Short Inter Frame Spacing
  • DIFS (MAX) gt PIFS gt SIFS (MIN)

43
Basic Access Method CSMA/CA
  • Backoff Time Random() x aSlotTime

44
802.11 - Competing Stations - Simple Version
45
RTS/CTS
  • RTS Request To Sent.
  • CTS Clear To Sent
  • Duration/ID fields that define the period of time
    that the medium is to be reserved to transmit the
    actual data frame and the returning ACK frame

46
Network Allocation Vector NAV
  • The NAV maintains a prediction of future traffic
    on the medium based on duration information that
    is announced in RTS/CTS frames prior to the
    actual exchange of data
  • The duration information is also available in the
    MAC header of all frames sent during the CP other
    than PS-Poll Control frames

47
RTS/CTS/Data/ACK and NAV
48
Security
49
Basic Security Concerns
  • Impractical to stop RF signals from propagating
    beyond your premises
  • Parking lot attack, war-driving
  • Poorly configured networks can be woefully
    exposed
  • Hackers can be highly stealthy, guerilla warfare
    style
  • Thats the reason for WEP

50
Baseline Security Features
  • Wired Equivalent Privacy
  • Shared 40/128 bit key
  • Static, i.e. not designed to change often
  • RC4 stream cipher
  • Any AP/client can be configured to handle up to 4
    keys

51
Baseline Security Features
  • Mutual authentication
  • Open, i.e. null
  • Shared key (if WEP is enabled), MS-CHAP style
    challenge and response
  • Access control list at AP
  • based on MAC addresses of WLAN cards
  • Access Control List can be easily bypassed
  • MAC addresses can be sniffed from the air
  • clients MAC address can be easily spoofed
  • Service set ID (SSID)
  • secret word that identifies a WLAN segment
  • SSID is not a security feature
  • transmitted in the clear in beacon frames
  • clients can set as null string

52
Basic Security Concerns
  • Sniffing tools are easily available
  • Freeware
  • Ethereal Prism II card
  • Now can capture raw encrypted packets
  • Commercial tools
  • WildPacket Airopeek (2.5K)
  • NAI Sniffer Wireless ( 20K)
  • Others are available FREE on the web

53
Basic Security Concerns
  • Besides WEP key, no other credentials required to
    access WLAN network
  • Difficult to manage shared WEP key in large
    deployments
  • Keys are seldom changed, manual process
  • If a WLAN card is stolen, have to reconfigure all
    other WLAN cards configured with that same WEP
    key

54
The End of WEP?
  • Undeniable fact WEP in its current form is not
    secure
  • Security issues are now better understood
  • No false sense of security gt a good thing
  • Vendors have always advocated higher level
    security is needed anyway
  • e.g. VPN, IPSec

55
IPSec
56
IPSec Sessions
57
802.11g
  • Newest standard provides for up to 54 Mbps data
    transfers within the 2.4 GHz band.
  • 802.11g devices will be backwards compatible with
    802.11b.
  • Potentially enables 2.4 GHz-based 802.11b
    networks to easily upgrade to future 802.11g
    networks
  • Consumers confusion with 802.11a and 802.11g
    standards entering the market simultaneously
  • Cellular phone service providers are considering
    augmenting their "3G" third generation digital
    cellular networks with support of the unlicensed
    WLAN devices, particularly in peak usage areas in
    downtown cities and at airports

58
Something for Everyone
59
HomeRF Roadmap
60
Bluetooth Lose the Cable!
61
Overview of Bluetooth
  • Bluetooth is
  • Short-range radio technology
  • Class 1 (100 m) 20dBm max to 0 dBm w/ power
    control
  • Class 2 ( 30 m) 4 dBm to -6 dBm
  • Class 3 ( 10 m) 0 dBm max
  • Connections without cables
  • Laptops, Cell phones, PDAs, Printers, etc
  • Royalty-free
  • IEEE Standard through 802.15 (PAN)

62
Overview of Bluetooth
  • Bluetooth Applications
  • Internet and email bridge
  • Ad Hoc network via access point
  • Home networking
  • Hidden computing
  • Wireless wallet
  • Laptop and PDA to cell phone modem
  • Headset
  • Digital camera

63
Who Was Bluetooth?
  • Harald Blaatand Bluetooth II
  • King of Denmark 940-981
  • Son of Gorm the Old (King of Denmark) and Thyra
    Danebod (daughter of King Ethelred of England)
  • This is one of two Runic stones erected in his
    capitol city of Jelling (central Jutland)
  • This is the front of the stone depicting the
    chivalry of Harald.
  • The stones inscription (runes) say
  • Harald Christianized the Danes
  • Harald controlled Denmark and Norway
  • Harald thinks notebooks and cellular phones
    should seamlessly communicate

Source Jim Kardach, Intel
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  • Typically used for voice.
  • Guaranteed bandwidth
  • No re-transmission.
  • Typically used for data.
  • Point to multi-point.
  • Reliable data (error correction /
    re-transmission)
  • No guaranteed bandwidth (best
    effort).

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Mutual Interference Problems
  • IEEE 802.11 and Bluetooth both operate in same
    2.4 GHz ISM Band
  • Bluetooth enabled devices likely to be portable
    and need to operate in IEEE 802.11 WLAN
    environment
  • There will be some level of mutual interference

Source John Barr Company Motorola IEEE
802.15 Report at BT DevCon
74
Coexistence Mechanisms
  • Collaborative Mechanisms
  • Communication between the WLAN and WPAN
  • Provide fair sharing of medium through link
  • Non-Collaborative Mechanisms
  • No communication between WLAN and WPAN
  • Techniques minimize effects of mutual
    interference

Source John Barr Company Motorola IEEE
802.15 Report at BT DevCon
75
Impact of Bluetooth on 802.11b
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77
National Semiconductor Wireless Solutions for
802.11 and Bluetooth
  • First to market with BT 1.O compliance
  • 802.11a/b/g solution
  • Expect to meet all mandatory parts of 802.11g
  • Complete solutions
  • Development boards for Radio and Baseband
  • Reference boards for MiniPCI and PCMCIA
  • Drivers and utilities
  • Bluetooth PC Card, Compact Flash, and Printer
    Adapters solutions shipping now

78
Thank you!
Dwight Borses d.borses_at_ieee.org
http//www.comsoc.org/comsig/
78
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