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Baisa 03/28/01 1 IEEE Orange County Computer Society Joint Meeting with IEEE OC ComSig Chapter Wireless LAN Instrumentation, Scientific, Medical Band Dwight.

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Presentation on theme: "Baisa 03/28/01 1 IEEE Orange County Computer Society Joint Meeting with IEEE OC ComSig Chapter Wireless LAN Instrumentation, Scientific, Medical Band Dwight."— Presentation transcript:

1 Baisa 03/28/01 1 IEEE Orange County Computer Society Joint Meeting with IEEE OC ComSig Chapter Wireless LAN Instrumentation, Scientific, Medical Band Dwight Borses MTS, Field Applications Engineering National Semiconductor, Irvine,CA Feb 25, 2002

2 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 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 4 Wireless Technologies: Short Distance

5 Infrared A real standard that sort of died

6 6 Wireless Technologies: Long Distance

7 M 384 K 144 K 64 K 14.4 K 9.6 K 1G Analogue Cellular 1G Analogue Cellular 2G IS-95-A Circuit Switched + QNC 2G IS-95-A Circuit Switched + QNC 2.5G IS-95B Packet Data 2.5G IS-95B Packet Data 3G Phase I IS-2000 Rel 0 (1XRTT) Packet Data 3G Phase I IS-2000 Rel 0 (1XRTT) Packet Data 3G Phase II IS-2000 Rel A (3XRTT) Packet Data / Voice / Video 3G Phase II IS-2000 Rel A (3XRTT) Packet Data / Voice / Video 3G Fixed access at 2Mbps 3G Fixed access at 2Mbps Subscriber Data Rate Data Migration Path to 3G WWAN

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11 11 2.4GHz ISM Band

12 12 ISM Band Inhabitants (Besides ) Frequency & Modulation Specs

13 13 Comparing Different WLAN Technologies

14 14 5 GHz Unlicensed National Information Infrastructure

15 15 IEEE 802 Framework

16 Standards Overview IEEE a b i h802.11d e f g

17 Standards Original , circa 1999 –FHSS, DSSS, IR –1 & 2 Mbps –Wired Equivalent Privacy (WEP) –SNMP v2 for remote management b (shortly after ) –DSSS –1, 2, 5.5 & 11 Mbps, Complementary Code Keying (CCK)

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

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

21 21 Wireless Data Standards Technology Comparison

22 22 PANs, LANs, and Bluetooth

23 23 EHF (milli-wave) SHF (micro-wave) VHF UHF Wired LAN Middle Speed 2.4GHz Range LAN High Speed 5GHz Range LAN Very High Speed 60 GHz Range LAN 4Mbps/16Mbps Token Ring IEEE Mbps Ethernet IEEE /52/100Mbps ATM-LAN (ATM Forum) 100Mbps Fast Ethernet IEEE 802.3u 156/622 Mbps ATM-LAN (ATM Forum) 1000Mbps Gigabit Ethernet IEEE 802.3z, 802.3ab Bandwidth Frequency IEEE Mbps/2Mbps IEEE802.11b 5.5Mbps/11Mbps (1)IEEE a 6/12/24Mbps (2)HIPERLAN (ETSI BRAN) Type ½: 23.5/25Mbps (3)WATM (ATM Forum) 25Mbps 19GHz range LAN 10Mbps (ARIB) (1)156Mbps MMAC(Japan) (2)156Mbps MEDIAN (German) 300GHz 30GHz 3GHz 300MHz 1GHz Full Range of Wireless LANs

24 24 Data Rates and Range by Technology

25 – Infrastructure Architecture

26 Layers and Functions

27 27 Binary Phase Shift Keying Quadrature Phase Shift Keying

28 28 Quadrature Modulation

29 29 Quadrature Amplitude Modulatoion

30 30 IEEE Direct Sequence Spread Spectrum DSSS

31 31 Frequency Hopping Spread Spectrum (FHSS) Freq. f1 f2 f3 f4 f5 f6 f7 Time t1 t2t3t4 t5 t6 AU 1 AU 2 AU 4 AU 3 Transmitted signal is spread over a wide range of frequencies (ISM GHz) Transmission hops 8 to 30 times per second

32 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 33 Complementary Code Keying This sequence has 4 pairs of unlike elements with separation of 1 and 3 pairs of like elements.

34 Modulation Set

35 35 Binary Phase Shift Keying

36 36 IEEE a OFDM


38 38 CSMA/CD –Carrier Sense, Multiple Access/Collision Detection For wire communication No control BEFORE transmission –Generates collisions Collision Detection –How?

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

40 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 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 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) > PIFS > SIFS (MIN)

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

44 Competing Stations - Simple Version

45 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 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 47 RTS/CTS/Data/ACK and NAV

48 48 Security

49 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 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 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 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 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 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 => a good thing Vendors have always advocated higher level security is needed anyway –e.g. VPN, IPSec

55 55 IPSec

56 56 IPSec Sessions

57 g Newest standard provides for up to 54 Mbps data transfers within the 2.4 GHz band g devices will be backwards compatible with b. Potentially enables 2.4 GHz-based b networks to easily upgrade to future g networks Consumers confusion with a and g 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 58 Something for Everyone

59 59 HomeRF Roadmap

60 60 Bluetooth: Lose the Cable!

61 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 (PAN)

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

63 63 Who Was Bluetooth? Harald Blaatand Bluetooth II –King of Denmark –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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71 71 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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73 73 Mutual Interference Problems IEEE and Bluetooth both operate in same 2.4 GHz ISM Band Bluetooth enabled devices likely to be portable and need to operate in IEEE WLAN environment There will be some level of mutual interference Source: [John Barr] Company [Motorola] IEEE Report at BT DevCon

74 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 Report at BT DevCon

75 75 Impact of Bluetooth on b:

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77 77 National Semiconductor Wireless Solutions for and Bluetooth First to market with BT 1.O compliance a/b/g solution –Expect to meet all mandatory parts of g 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 78 Thank you! Dwight Borses

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