Wireless Communication: at WMU and beyondbazuinb/WiFi_WL_WMU.pdf21 February 2003 CEAS Weekly Seminar...

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


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


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.


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)


FCC Allocation Chart

Adobe Acrobat Document

http://www.ntia.doc.gov/osmhome/allochrt.html

http://www.ntia.doc.gov/osmhome/allochrt.pdf


AM, FM and TV

http://wireless.fcc.gov/auctions/data/bandplans.html


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


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


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


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)


IEEE 802 Standard

Reference Model

From: IEEE Std 802 ® -2001, IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture


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.


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


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.


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


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


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


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


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


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


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


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]


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”


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.


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


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


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


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


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.


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


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/


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


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


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)


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


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


RF Chamber Lab Space

• Kohrman 3059 RF Chambers: – Two 10x10 metal boxes


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


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


• 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


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


Chaotic Communication

• Dr. Damon Miller and Dr. Giuseppe Grassi– Reference: http://homepages.wmich.edu/~miller/


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


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


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


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


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

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