Presentation on theme: "MTS, Field Applications Engineering National Semiconductor, Irvine,CA"— Presentation transcript:
1MTS, Field Applications Engineering National Semiconductor, Irvine,CA IEEE Orange County Computer Society Joint Meeting with IEEE OC ComSig Chapter Wireless LAN Instrumentation, Scientific, Medical BandDwight BorsesMTS, Field Applications EngineeringNational Semiconductor, Irvine,CAFeb 25, 2002
2Local volunteers needed! 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!
3Points to Ponder Standards - so many to choose from Cellular/PCS - both a competitor and a complement to WLANDECT – up-banded applications for proprietary applicationsUWB – yet another contenderFSO – Light based wireless
12ISM Band Inhabitants (Besides 802.11) Frequency & Modulation Spec’s 3/28/2017ISM Band Inhabitants (Besides ) Frequency & Modulation Spec’sThe data transmitted has a symbol rate of 1 Ms/s.A Gaussian-shaped, binary FSK modulation( is applied with a BT product of 0.5). A binary one is represented by a positive frequency deviation, a binary zero by a negative frequency deviation. The maxmium frequency deviation shall be between 140 khz and 175 kHz. The transmitted initial center frequency accuracy must be +75 kHz from Fc. Note that the frequency drift is not included in 75 kHz.For bluetooth, each slot is 625 us and for multislot packets, Packets transmitted may extend over up to 5 times slots.Drift must be less than 40 kHz.Notes costs and tight specification.
17802.11 Standards Original 802.11, circa 1999 FHSS, DSSS, IR1 & 2 MbpsWired Equivalent Privacy (WEP)SNMP v2 for remote management802.11b (shortly after )DSSS1, 2, 5.5 & 11 Mbps, Complementary Code Keying (CCK)
18802.11 Standards 802.11a (Approved same time as .11b) 6, 9, 12, 18, 24, 36, 48, 54 MbpsOnly 6, 12, 24 Mbps support is mandatory5 GHz UNII band (not universally free)
19802.11 Standards 802.11c (completed, subsumed into d) Bridge operation802.11d (ongoing)Specs for other regulatory domains802.11e (ongoing)QoS (Security moved to i (May 2001))802.11f (ongoing)Inter Access Point interoperability
20802.11 Standards 802.11g (ongoing) 802.11h (ongoing) 802.11i (ongoing) High-speed extension to b, > 20MbpsJust approved!802.11h (ongoing)improvement to a, w.r.t. power and spectrum management802.11i (ongoing)Security enhancements
21Wireless Data Standards Technology Comparison 3/28/2017Wireless Data Standards Technology Comparison
23Full Range of Wireless LANs EHF (milli-wave)SHF (micro-wave)VHFUHFWired LANMiddle Speed 2.4GHz Range LANHigh Speed 5GHz Range LANVery High Speed 60 GHz Range LAN4Mbps/16Mbps Token Ring IEEE 802.510Mbps Ethernet IEEE 802.325/52/100Mbps ATM-LAN (ATM Forum)100Mbps Fast Ethernet IEEE 802.3u156/622 Mbps ATM-LAN (ATM Forum)1000Mbps Gigabit Ethernet IEEE 802.3z, 802.3abBandwidthFrequencyIEEE Mbps/2MbpsIEEE802.11b 5.5Mbps/11Mbps(1)IEEE a 6/12/24Mbps(2)HIPERLAN (ETSI BRAN) Type ½: 23.5/25Mbps(3)WATM (ATM Forum) 25Mbps19GHz range LAN 10Mbps (ARIB)156Mbps MMAC(Japan)156Mbps MEDIAN (German)300GHz30GHz3GHz300MHz1GHz
30IEEE 802.11 Direct Sequence Spread Spectrum DSSS
31Frequency Hopping Spread Spectrum (FHSS) Transmitted signal is “spread” over a wide range of frequencies (ISM GHz)Transmission hops 8 to 30 times per secondFreq.f1f2f3f4f5f6f7Timet1t2t3t4t5t6AU 1AU 2AU 4AU 3
32Complementary 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
33Complementary Code Keying This sequence has 4 pairs of unlike elements with separation of 1 and 3 pairs of like elements.
38CSMA/CD CSMA/CD For wire communication No control BEFORE transmission Carrier Sense, Multiple Access/Collision DetectionFor wire communicationNo control BEFORE transmissionGenerates collisionsCollision DetectionHow?
39CSMA/CA CSMA/CA For wireless communication Carrier Sense, Multiple Access/Collision AvoidanceFor wireless communicationCollision avoidance BEFORE transmissionPre-avoidance of collisionWhy avoidance on wireless?
40Collision Detection On Wireless? Difference on energy/power for transmit and receiveAt maximum, transmission power is a million times larger than receivingVery hard to detect because of this differenceEnergy often matter on wireless environmentPortable devices/terminals with batteries
41Backoff Decrease the possibility of contention/collision Backoff windowTime to wait ot avoid collisionRandom backoffUse random length of time to wait
42IFS – Inter Frame Spacing Defined length of time for controlTo assure the control of multiple accessDIFS – Distributed Inter Frame SpacingPIFS – Point Inter Frame SpacingSIFS – Short Inter Frame SpacingDIFS (MAX) > PIFS > SIFS (MIN)
43Basic Access Method: CSMA/CA Backoff Time = Random() x aSlotTime
45RTS/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
46Network 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 dataThe duration information is also available in the MAC header of all frames sent during the CP other than PS-Poll Control frames
49Basic Security Concerns Impractical to stop RF signals from propagating beyond your premises“Parking lot” attack, war-drivingPoorly configured networks can be woefully exposedHackers can be highly stealthy, guerilla warfare styleThat’s the reason for WEP
50Baseline Security Features Wired Equivalent PrivacyShared 40/128 bit keyStatic, i.e. not designed to change oftenRC4 stream cipherAny AP/client can be configured to handle up to 4 keys
51Baseline Security Features Mutual authenticationOpen, i.e. nullShared key (if WEP is enabled), MS-CHAP style challenge and responseAccess control list at APbased on MAC addresses of WLAN cardsAccess Control List can be easily bypassedMAC addresses can be sniffed from the airclient’s MAC address can be easily spoofedService set ID (SSID)“secret” word that identifies a WLAN segmentSSID is not a security featuretransmitted in the clear in beacon framesclients can set as null string
52Basic Security Concerns Sniffing tools are easily availableFreewareEthereal + Prism II cardNow can capture raw encrypted packetsCommercial toolsWildPacket Airopeek (~$2.5K)NAI Sniffer Wireless (~ $20K)Others are available FREE on the web
53Basic Security Concerns Besides WEP key, no other credentials required to access WLAN networkDifficult to manage shared WEP key in large deploymentsKeys are seldom changed, manual processIf a WLAN card is stolen, have to reconfigure all other WLAN cards configured with that same WEP key
54The End of WEP? Undeniable fact: WEP in its current form is not secure Security issues are now better understoodNo false sense of security => a good thingVendors have always advocated higher level security is needed anywaye.g. VPN, IPSec
57802.11gNewest standard provides for up to 54 Mbps data transfers within the 2.4 GHz band.802.11g devices will be backwards compatible with b.Potentially enables GHz-based b networks to easily upgrade to future g networksConsumers confusion with a and g standards entering the market simultaneouslyCellular 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
61Overview of Bluetooth Bluetooth is: Short-range radio technology 3/28/2017Overview of BluetoothBluetooth is:Short-range radio technologyClass 1 (100 m) +20dBm max to 0 dBm w/ power controlClass 2 ( 30 m) + 4 dBm to -6 dBmClass 3 ( 10 m) dBm maxConnections without cablesLaptops, Cell phones, PDA’s, Printers, etcRoyalty-freeIEEE Standard through (PAN)Bluetooth is a low-cost, low-power, short-range radio technology. It was originally developed as a cable replacement to connect devices such as cell phone handsets and portable computers. It has been extended to include standardized wireless communications between any electrical device over a short range (maximum range of 100 meters using the high-power Class 1 mode). Bluetooth now represents the concept of a Personal Area Network (PAN), and it is intended to revolutionize the way people interact with the information infrastructure around them. It remains to be seen if Bluetooth can live up to this larger role.The technology was named after a Viking and King of Denmark who lived in the late 900’s (AD), whose real name was Harald Blaatand. He was the son of Gorm the Old and Thyra Danebod. Harald united and then ruled over both Denmark and Norway.The founding members of the Bluetooth Special Interest Group (SIG) are: Ericsson, Intel, IBM, Toshiba and Nokia.
62Overview of Bluetooth Bluetooth Applications: 3/28/2017Overview of BluetoothBluetooth Applications:Internet and bridgeAd Hoc network via access pointHome networkingHidden computingWireless walletLaptop and PDA to cell phone modemHeadsetDigital cameraAd Hoc network means a network dynamically created when you walk into a room with a Bluetooth device, and perform an inquiry to find out if any other Bluetooth devices are in the room and willing to talk to your Bluetooth device.
63Source: Jim Kardach, Intel Who Was Bluetooth?Harald Blaatand “Bluetooth” IIKing of DenmarkSon 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 stone’s inscription (“runes”) say:Harald Christianized the DanesHarald controlled Denmark and NorwayHarald thinks notebooks and cellular phones should seamlessly communicateSource: Jim Kardach, Intel
73Mutual Interference Problems IEEE and Bluetooth both operate in same 2.4 GHz ISM BandBluetooth enabled devices likely to be portable and need to operate in IEEE WLAN environmentThere will be some level of mutual interferenceSource: [John Barr] Company [Motorola]IEEE Report at BT DevCon
74Coexistence Mechanisms Collaborative MechanismsCommunication between the WLAN and WPANProvide fair sharing of medium through linkNon-Collaborative MechanismsNo communication between WLAN and WPANTechniques minimize effects of mutual interferenceSource: [John Barr] Company [Motorola]IEEE Report at BT DevCon
77National Semiconductor Wireless Solutions for 802.11 and Bluetooth First to market with BT 1.O compliance802.11a/b/g solutionExpect to meet all mandatory parts of gComplete solutionsDevelopment boards for Radio and BasebandReference boards for MiniPCI and PCMCIADrivers and utilitiesBluetooth PC Card, Compact Flash, and Printer Adapters solutions shipping now