21 February 2003 CEAS Weekly Seminar 1
Wireless Communication:at WMU and beyond
Dr. Bradley J. BazuinAssistant Professor
Western Michigan UniversityDept. of Electrical and Computer EngineeringCollege of Engineering and Applied Sciences
21 February 2003 CEAS Weekly Seminar 2
Agenda
Wireless communications:• Wireless Ethernet (WiFi or IEEE 802.11b)
– Connecting, security, and interference• IEEE 802.11 Alphabet Soup
– What is here or coming next• Bluetooth
– Wireless Personal Area Network• Wireless Communication Research
– Projects– Test and Measurement Equipment– Future Directions
21 February 2003 CEAS Weekly Seminar 3
Wireless Links and Networks
Satellite
Satellite dishTV
VideoMobile
Satellite
Wireless
Computers/Workstations
INTERNET
Radio TowerTelephony
Aircraft
Base Station
Laptop computer
We are constantly exposed to radio frequency (RF) waves, whether used for communications or radiated as interference.
21 February 2003 CEAS Weekly Seminar 4
Radio Frequency Bands
The Radio Frequency Spectrum extends from 3kHz to 300GHz. Spectrum use internationally and nationally regulated.
– International Telecommunications Union (ITU)– Federal Communication Commission (FCC)
21 February 2003 CEAS Weekly Seminar 5
FCC Allocation Chart
Adobe Acrobat Document
http://www.ntia.doc.gov/osmhome/allochrt.html
http://www.ntia.doc.gov/osmhome/allochrt.pdf
21 February 2003 CEAS Weekly Seminar 6
AM, FM and TV
http://wireless.fcc.gov/auctions/data/bandplans.html
21 February 2003 CEAS Weekly Seminar 7
Common RF Bands
• Cell Phones: 824-849 MHz and869-894 MHz
• PCS Bands: 1850-1910 MHz and1930-1990 MHz
• FCC Part 15 Unlicensed BandsInstrumentation, Scientific and Medical (ISM):
902 - 928 MHz and 2400 - 2483.5 MHz5725 – 5850 MHz
• Unlicensed National Information Structure (U-NII) bands:
5150 – 5350 MHz5725 – 5850 MHz
21 February 2003 CEAS Weekly Seminar 8
FCC PART 15RADIO FREQUENCY DEVICES
• Unlicensed Bands– Instrumentation, Scientific and Medical (ISM) Bands have been defined
> Frequency hopping and direct sequence spread spectrum intentional radiators> 902 - 928 MHz > 2400 - 2483.5 MHz> 5725 – 5850 MHz.
– Unlicensed national information structure (U-NII) bands
> 5150 – 5350 MHz and 5725 – 5850 MHz> 5725 – 5850 MHz.
• 2.4 GHz Unlicensed Wireless Standards and Users– IEEE 802.11b – Wireless Ethernet or WiFi – WMU’s Wireless Network– Bluetooth– Home Cordless Telephones
21 February 2003 CEAS Weekly Seminar 9
Wireless Communication Networks
Wireless Relative Range and Application
The phony conflict: IEEE 802.11 and Bluetooth wireless technology, Brent Miller ([email protected]), Sr. software engineer, IBM, October 2001, http://www-106.ibm.com/developerworks/library/wi-phone/
WWAN:Wireless Wide Area Network
WLAN: Wireless Local Area Network
WPAN: Wireless Personal Area Network
21 February 2003 CEAS Weekly Seminar 10
Model for Communications
Application
Presentation
Session
Transport
Network
Data Link
Physical
Wireless
WiredOptical
Application
Presentation
Session
Transport
Network
Data Link
Physical
LaptopWorkstation Telephone
Server
PDA
International Standards Organization (ISO)
Open System Interconnect Model (OSI)
21 February 2003 CEAS Weekly Seminar 11
IEEE 802 Standard
Reference Model
From: IEEE Std 802 ® -2001, IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture
21 February 2003 CEAS Weekly Seminar 12
IEEE 802 StandardsFamily of Standards
From: IEEE Std 802.15.1™-2002, Part 15.1: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Wireless Personal Area Networks (WPANs)
IEEE Std 802.11 [ISO/IEC 8802-11] : Wireless LAN Medium Access Control (MAC) Sublayer and Physical Layer Specifications.
IEEE Std 802.15 ....: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for: Wireless Personal Area Networks.
21 February 2003 CEAS Weekly Seminar 13
Commercial WiFi (802.11b)
• Ease of setup– Wireless Access Points connected using wired
infrastructure– Site Planning needed
• Wireless Security is a Problem but Improving– WEP: Wired Equivalent Privacy
Typically disabled, but when enabled a poor system– WPA: WiFi Protected Access
A promised of improved security
• Range, Capacity, and Interference ConcernsConcepts from: WiFi's Widening World, washingtonpost.com By Alan S. Kay, Special to The Washington Post, Sunday, December 22, 2002; Page H07
21 February 2003 CEAS Weekly Seminar 14
IEEE 802.11b
• Frequency Band Plan– unlicensed band from 2.4000 to 2.4835 GHz– up to 11 channels spaced at 5 MHz available
• Capacity– 11 Mbps wireless Ethernet connection
> Degraded performance options for 5.5 Mbps, 2 Mbps, and 1 Mbps– DSSS modulation with a required signal bandwidth of 22 MHz
From: ANSI/IEEE Std 802.11, 1999 Edition, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, p. 219.
21 February 2003 CEAS Weekly Seminar 15
Frequency Band Assignment
From: IEEE Std 802.11b-1999, (Supplement to ANSI/IEEE Std 802.11, 1999 Edition), Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher-Speed Physical Layer Extension in the 2.4 GHz Band, p. 49.
• Overlapping Channels May Interfere– Three clear channels: 1, 6, and 11– Others shown at 10 MHz spacing: 1, 3, 5, 7, 9, and 11
21 February 2003 CEAS Weekly Seminar 16
Site Planning
• Optimal Coverage of a space by alternating the three non-overlapping frequencies. – Notice that there are significant regions of dual
coverage– In many cases overlapping of the same band will occur– Range and data rate considerations
21 February 2003 CEAS Weekly Seminar 17
Friis Transmission Formula
Wireless Range Equation
where trP / is the received (or transmitted) signal power trG / is the effective antenna gain
R is the distance between the transmitter and receiver, andλ is the wavelength
( )2
2
4 RGGPP rt
tr ⋅⋅⋅⋅⋅=
πλ
r
rtt
r
rtt
PGGP
fc
PGGPR ⋅⋅⋅
⋅⋅=⋅⋅⋅
⋅=
ππλ
44
where c is the speed of light and f is the frequency
21 February 2003 CEAS Weekly Seminar 18
Wireless Range Example
Assumptions:Tx Power (Pt):
+23 dBm (200 mW)Tx Antenna Gain (Gt):
0 dBRcv Antenna Gain (Gr):
-20 dB
WiFi Receiver Sensitivity:11 Mbps: -87 dBm (1000 ft.)5.5 Mbps: -90 dBm (1500 ft.) 2 Mbps: -93 dBm (2000 ft.)1 Mbps: -95 dBm (2600 ft.)
Received Signal Power from +23 dBm Trasnmitter
-110
-100
-90
-80
-70
-60
-50
-4010.0 100.0 1000.0 10000.0
Distance (ft)
Pow
er (d
Bm)
916 MHz2.4 GHz5.2 GHz
Power and Sensitivity values based on: Surf and Sip’s Supercharged WiFi Card www.surfabdsip.com/ps_superchargedcard.htm
21 February 2003 CEAS Weekly Seminar 19
Obstruction Assumptions:Distance
approx. 50 ft.Signal Attenuation
10 dB
WiFi Receiver Sensitivity:11 Mbps: -87 dBm (300 ft.)5.5 Mbps: -90 dBm (400 ft.)2 Mbps: -93 dBm (600 ft.)1 Mbps: -95 dBm (800 ft.)
Wireless Range with Obstruction
Received Signal Power from +23 dBm Trasnmitterwith a 10dB loss at 50 ft.
-110
-100
-90
-80
-70
-60
-50
-4010.0 100.0 1000.0 10000.0
Distance (ft)
Pow
er (d
Bm)
916 MHz2.4 GHz5.2 GHz
Power and Sensitivity values based on: Surf and Sip’s Supercharged WiFi Card www.surfandsip.com/ps_superchargedcard.htm
21 February 2003 CEAS Weekly Seminar 20
Site Planning Design
• Performed prior to system installation– Kohrman 3rd Floor
> A team of two performed a site survey with test instruments to determine signal propogation and expected access point antenna placement
> In the space of the 3rd floor, 11 access points were initially defined.– Additional range available
> Clear line-of-sight, out door installation> Directional antennas with higher gain in specific directions
• Site characteristics can and do change– Building modifications effect the plan, particularly electrical
changes, metal wall studs, metal sheeting, ceiling tiles, etc.– Move or add access points
21 February 2003 CEAS Weekly Seminar 21
WiFi Interference
• Rogue WiFi Networks– Setting up your own small network
• Bluetooth– PAN 802.15 peer-to-peer device communication– Significant presence in Europe and Japan– Potential automobile network
• Cordless Telephones– New models have moved to higher frequencies from 915 MHz
• Microwave Ovens (MWO Interference)– Cheap magnetron oscillators when shielded can still output
sufficient RF energy to interfere with WiFi receivers
21 February 2003 CEAS Weekly Seminar 22
WiFi Interference Concerns
• Interference
• Students, faculty, and staff “will” support OIT• Continued RF monitoring and management is needed!
OIT will approach the shared use of the 2.4 GHz radio frequency in the same way that it manages the shared use of the wired network. While we will not actively monitor use of the airspace for potential interfering devices, we will seek out the user of a specific device if it is causing interference and disrupting the campus network. In these cases, OIT reserves the right to restrict the use of all 2.4 GHz radio devices in university-owned buildings and all outdoor spaces on the WMU campus. See the OIT policies and procedures for information on WMU computing policies, including those related to responsible use of shared resources, such as the 2.4 GHz radio frequency in this case. [http://www.wmich.edu/oit/wireless/guidelines.html]
21 February 2003 CEAS Weekly Seminar 23
Do We Want Wireless to Connect ?
• The use of laptops and PDAs in exams– Will the students find ways to cheat?
• Can we turn the networks off?– Yes, for IEEE 802.11. But it is probably not practical.
• Is there another way to “block” the connections– Possibly, grounded metal sheets “absorb” the RF signals
(cookie sheet, large metal bowl, etc.)– Install jammers
• If we succeed are there other wireless systems?– Yes, Bluetooth is peer-to-peer network– Cell phones now have text messaging and are adding internet
• Monitoring Equipment?– Society of Old Crows: “In God we trust, all others we monitor”
21 February 2003 CEAS Weekly Seminar 24
FCC Blocking and Jamming• The Communications Act of 1934, as amended, and the Commission's rules do not permit the use of
transmitters designed to prevent or jam the operation of wireless devices in hospitals, theaters and other locations. Section 302(a) of the Communications Act, 47 USC 302(a), prohibits the manufacture, importation, sale, offer for sale, or use of devices that fail to comply with the regulations promulgated pursuant to this section. Similar prohibitions are contained in the Commission's rules, e.g., 47 CFR Sections 2.803, 2.1203, and 22.377.
• In addition, in accordance with Section 301 of the Communications Act, 47 USC 301, persons operating or using radio transmitters must be licensed or authorized under the Commission's rules. There are no provisions in the FCC's rules that permit the operation of any device intended to interfere with wireless communications. Further, Section 333 of the Communications Act, 47 USC 333, prohibits any person from willfully or maliciously interfering with the radio communications of any station licensed or authorized under the Communications Act or operated by the U.S. Government.
• Based on the above, the operation of transmitters designed to jam wireless communications is a violation of 47 USC 301, 302(a), and 333. The manufacture, importation, sale or offer for sale, including advertising, of such transmitters is a violation of 47 USC 302(a). Parties in violations of these provisions may be subject to the penalties contained within 47 USC 501-510. Fines for a first offense can range as high as $11,000 for each violation or imprisonment for up to one year. The equipment can also be seized and forfeited to the U.S. Government. These regulations apply to all transmitters that are designed to cause interference to, or prevent the operation of, other radio communication systems.
21 February 2003 CEAS Weekly Seminar 25
WiFi Alphabet Soup
• IEEE 802.11b: WiFi• IEEE 802.11a:
– Unlicensed national information structure (U-NII) bands
> 5150 – 5350 MHz and 5725 – 5850 MHz> 5725 – 5850 MHz.
– 54 Mbps wireless Ethernet connection • IEEE 802.11g
– WiFi Frequency Band, extended data rates– 54 Mbps wireless Ethernet connection
21 February 2003 CEAS Weekly Seminar 26
WiFi Alphabet Soup
• IEEE 802.11e:– Enhance 802.11 Medium Access Control (MAC) to improve and
manage Quality of Service, provide classes of service, and enhance security and authentication mechanisms.
– VoIP, video conferencing, multimedia
• IEEE 802.11h:– Enhance 802.11 Medium Access Control (MAC) and 802.11a in
the 5 GHz band.
• IEEE 802.11i:– Enhance 802.11 Medium Access Control (MAC) to enhance
security and authentication mechanisms
• IEEE 802.15: Bluetooth– The other 2.4 GHz system http://www.wlana.org/pdf/wlan_standards_orgs.pdf
21 February 2003 CEAS Weekly Seminar 27
IEEE 802.11a
• Unlicensed national information structure (U-NII) bands– 5150 – 5350 MHz and 5725 – 5850 MHz– 12 non-overlapping channels available
• Signaling– OFDM Modulation: Orthogonal Frequency Division Multiplexed
(Hybrid signal using QAM symbols in FFT bins)– Mandatory rates 6, 12, and 24 Mbps– Optional rates 9, 18, 36, 48, or 54 Mbps
21 February 2003 CEAS Weekly Seminar 28
OFDM Modulation
From: IEEE Std 802.11a-1999, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications High-speed Physical Layer in the 5 GHz Band, p. 27.
Inverse FFT Bins
•••
•••
QAM Constellation
21 February 2003 CEAS Weekly Seminar 29
Frequency Bands
• IEEE 802.11a: 12 non-overlapping bands
From: IEEE Std 802.11a-1999, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications High-speed Physical Layer in the 5 GHz Band, p. 27.
21 February 2003 CEAS Weekly Seminar 30
IEEE 802.11g
• Frequency Band Plan– Unlicensed band from 2.4000 to 2.4835 GHz– 11 channels spaced at 5 MHz available
• Signaling– Higher rates in the 802.11b band, up to 54 Mbps– OFDM Modulation: Orthogonal Frequency Division Multiplexed
(Hybrid signal using QAM symbols in FFT bins)– Fall back capability to 802.11b rates and signaling
• Emerging Hardware– Interoperability problems exist for some tested devices
http://www.wlana.org/pdf/highspeed.pdf
21 February 2003 CEAS Weekly Seminar 31
IEEE 802.15 !!!! Bluetooth
• IEEE Std 802.15.1™-2002– Part 15.1: Wireless Medium Access Control (MAC) and
Physical Layer (PHY) Specifications for Wireless Personal Area Networks (WPANs)
• Bluetooth – A Danish King• A Peer-to-Peer network in the 2.4 GHz ISM band
http://www.bluetooth.com/tech/works.asp
http://www.bluetooth.com/
21 February 2003 CEAS Weekly Seminar 32
Bluetooth
• 2.4 GHz ISM Band Peer-to-Peer – Personal Area Network, (PSAs, phones, mics, devices)– Uses frequency hopping, 79-1 MHz channels
• Short range device interconnection– Near device interference, range dependent (nom 1 mW)
http://www.wlana.org/learn/reliabwlan.pdf
Access Point Range BT Range20m 9.95m10m 3.66m4m 1.27m
21 February 2003 CEAS Weekly Seminar 33
Bluetooth and WiFi
• BT and WiFi ?! – Wi-Fi solves bandwidth-heavy, network-based (whether intranet or
Internet) connectivity; – Bluetooth offers ad hoc, resource-based opportunistic availability.– Interference can be understood and dealt with– From: Wi-Fi Networking News, Wednesday, February 6, 2002,
http://80211b.weblogger.com/2002/02/06
• For Bluetooth Versus WiFi– See: http://www.tadlys.com/Bluetooth-white-Papers.htm
21 February 2003 CEAS Weekly Seminar 34
Wireless Communication Systems
• Why have these systems come about?– The inevitable push of technology … yes but …
• Technological Advancements– Signal Processing Developments– Communications Protocols– Microwave, RF, and Digital ICs– Microprocessors and Microcontrollers– Software Radio Architectures (All-Digital Radios)
21 February 2003 CEAS Weekly Seminar 35
Software Transceivers
• RF frontend, high speed ADC & DAC, and digital signal processing– Technology: RF and analog design, Digital and computer design,
signal processing, real-time software programming, and networking.
IBM Compatible
RF to IFReceiver
A to DConvert
DigitalDown-
Converter
DigitalSignal
Processor
Digital Up-Converter
D to AConvert
IF to RFTransmit
Comm. Tower
Satellite
21 February 2003 CEAS Weekly Seminar 36
Resources and Research
• RF Prototyping, Test, and Measurement Lab– Acquisition of RF test equipment and prototyping modules
> CEAS startup funds> Donations from BAE Systems> Michigan Space Grant Consortium with WMU matching
• Projects– FEAST: Flexible Electrical and Software Programmable
Transceiver– Chaotic Carrier Communications– Wireless Smart Sensor Systems– Bluetooth Prototype Monitoring System and IP Development– Various GPS based projects– Incorporation of simple wireless communications into multiple
Senior Design Projects
21 February 2003 CEAS Weekly Seminar 37
RF Chamber Lab Space
• Kohrman 3059 RF Chambers: – Two 10x10 metal boxes
21 February 2003 CEAS Weekly Seminar 38
RF Test Equipment• Agilent 4396B Spectrum/Network Analyzer (10 Hz to 1.8 GHz)• Two RF Synthesized Signal Sources (to 990 MHz and 2.2 GHz)• Power Supplies (Agilent 2 dual and 2 single supplies)• Misc. older equipment
21 February 2003 CEAS Weekly Seminar 39
Components
• Minicircuits: Amplifiers, mixers, splitters, VCOs, Filters, and attenuators
• Cables: SMA cables with terminators• Custom designed and constructed modules:
– SAW BP Filter, test fixtures, VCO control circuitry
21 February 2003 CEAS Weekly Seminar 40
• Projects– FEAST: Flexible Electrical and Software Programmable
Transceiver– Chaotic Carrier Communications– Wireless Smart Sensor Systems– Bluetooth Prototype Monitoring System and IP Development– Various GPS based projects– Incorporation of wireless communications into multiple Senior
Design Projects> Flowserve Pump and Motor Monitor, Low Cost Local Area
Differential GPS, etc.
Research Projects
21 February 2003 CEAS Weekly Seminar 41
MSGC Research: FEAST
• Provide the nucleus and resources to define, develop, and demonstrate an initial prototype of the flexible, electrical and software programmable transceiver(FEAST) for wireless communications.
• Seed Grant and Student Research http://homepages.wmich.edu/~bazuinb/BJB_Research.htm
21 February 2003 CEAS Weekly Seminar 42
Chaotic Communication
• Dr. Damon Miller and Dr. Giuseppe Grassi– Reference: http://homepages.wmich.edu/~miller/
21 February 2003 CEAS Weekly Seminar 43
Wireless Smart SAW Sensor Systems
• Dr. Massood Atashbar and Sridevi KrishnamurthyThis work is partially funded by an NSF grant, 02-039 Integrated Smart Wireless SAW Sensors and Systems.
IDTInput/Output Antenna Reflectors
Piezoelectric Crystal
Reflectedresponse
Burst Input
BurstModulator
PowerAmplifier
BurstGenerator
RF to IFReceiverADC
IntelligentM icro-
ControllerSAW
Sensor
T/RSwitch
SampleBuffer
Low NoiseAmplifier
Netw
orkInterface
21 February 2003 CEAS Weekly Seminar 44
Future Wireless Directions
• RF-ID, Bluetooth, or WiFi based material tracking and position location
• 3G and 4G Telephony– Novel signal generation– Smart antenna system integration– Bandwidth on demand
• RF Interference Mitigation– Temporal narrowband cancellation– Smart antenna spatial cancellation
21 February 2003 CEAS Weekly Seminar 45
References
• Trade Associations– http://www.wlana.org– http://www.wi-fi.org or http://www.weca.net– http://www.bluetooth.com
• Standards Bodies– http://www.fcc.gov– http://www.ieee.org– http://etsi.org
21 February 2003 CEAS Weekly Seminar 46
References• Security Information
– http://www.isaac.cs.berkeley.edu/isaac/wep-faq.html– http://www.cs.umd.edu/~waa/wireless.html
• Tutorials and General Information– http://www.80211-planet.com/tutorials/
• 802.11a and g– http://www.infoworld.com/article/03/02/17/07gvsa_1.html
• 802.11g demos– http://www.infoworld.com/article/03/02/14/07nelink_1.html
21 February 2003 CEAS Weekly Seminar 47
Wireless Communication:at WMU and beyond
Dr. Bradley J. BazuinWestern Michigan University, CEAS
Dept. of Electrical and Computer [email protected]
http://homepages.wmich.edu/~bazuinb