Which Wireless Where?Applying wireless technology

from the rooftop to the desktop

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Ernest Schirmer RCDD/NTS CTS Senior Engineer

Vanderweil Engineers101 Grovers Mill Road

Lawrenceville NJ 08648

Which Wireless Where?Applying wireless from the rooftop to the desktop

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Agenda

• The wireless spectrum

• Frequency assignments

• Types of wireless technologies

• WiFi evolution review

• WiFi design criteria

• Quick-and-dirty WiFi design

• To Learn More references

WirelessDo what you have to do

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Wireless Applications• Voice: telephony, radio

• Data: wireless networks

• Security: cameras and sensors

• Video: displays

• Building automation and control

• Telemetry

• Tracking: GPS, RFID

•Machine-to-Machine (M2M)

• The Internet of Things (IoT)

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The Frequency Spectrum

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Terminology

Common Frequency Prefixes: At higher frequencies, prefixes are used to eliminate the need to write out the entire number.

• Kilo = 1,000 (thousand)•Mega = 1,000,000 (million)• Giga = 1,000,000,000 (billion)• Tera = 1,000,000,000,000 (trillion)

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Frequency Allocations– AM Radio: 580 to 1610 Kilohertz (KHz)– VHF Public Safety: 30 – 46 MHz – VHF TV Ch 2-6: 54 - 88 Megahertz (MHz)• What happened to TV channel 1?

– VHF TV Ch 7-13: 174 to 216 MHz• What’s in the gap between TV channels 6 and 7?

– FM Radio: 88 - 108 MHz– Aviation: 108 to 136 MHz– VHF Public Safety: 152 – 162 MHz– UHF Public Safety: 406 -512 MHz

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TerminologyFrequency: The number of times per second a signal repeats. The term “Hertz” (abbreviated Hz) is used instead of cycles per second to honor the German scientist, Gustav Hertz.

For example, the note A440(A above middle C) vibrates261.6 times per secondor 261.6 Hz. 8

TerminologyWavelength: The physical distance between identical points of a (sinusoidal) signal.

Wavelength in meters= 300/frequency in Hertz60 GHz = 0.005 meters (5 mm – 0.196”)5.0 GHz = 0.06 meters (60 mm – 2.36”)2.5 GHz = 0.120 meters (120 mm – 4.72”)94.5 MHz = 3.17 meters (10.4’)880 KHZ = 340.76 meters (1,118.18’)440 Hz = 681,818 meters (2,236,363’)

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Frequency Allocations

AM Radio

TV TV2/4 5/6

TVFM

TV7/13

Primary UnlicensedFrequency Allocations

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928MHz902MHz 5.850GHz5.725GHz2.4835GHz2.4000GHz

900MHz 2.4GHz 5.8GHz

The 2.4 GHz band is authorizedworldwide for unlicensed operations.

Terminology

Licensed Radio Operations: A frequency or radio service that requires coordination with other users, the approval of the Federal Communications Commission and the issuing of a radio license.

Examples of licensed services:l Commercial AM/FM and TV stationsl Fire, police and EMS radiosl Some microwave systems

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TerminologyUnlicensed Radio Operations: A frequency or radio service that does not require a license from the Federal Communications Commission.

Examples of unlicensed services:lMicrowave ovensl Cordless phonesl Citizen band and Family Radio Servicel Remote control cars and planesl Garage door openers

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Unlicensed Operations– Unlicensed radio equipment:• Baby monitors, cordless phones,• Family Radio Service, itinerant handheld

radios, etc.– Industrial, Medical, Scientific (ISM)• 6.78/13.560/27.12/40.68/433.92/915 MHz• 2.450/5.80/24.125/61.25/122.5/245 GHz– 5.150-5.350 GHz US)– 5.725-5.825 GHz (Canada)

– No FCC protection from interference.

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Types of Wireless Connectivity

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Range vs. Technology

• Ultra short-range: Near-Field Communications• Very short-range: Zigbee• Short-range: Bluetooth, Ultra-Wide Band• Enterprise: WiFi• Metro or Campus: WiMAX• Point-to-Point: Microwave, infrared, laser

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Range vs. Data Rate

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Ultra Short-rangeNear Field

CommunicationsNFC

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NFC

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NFC– 13.56 MHz worldwide unlicensed band– Range: 4 inches– Data Rate: 100 – 400 Kbps– Power: 100 nanowatts.– Relatively unaffected by conductive (metal) objects or

people.–Most Android phones can program NFC tags

The strength of the magnetic field “bubble” decreases at the 6th power with distance compared to radiated electric fields which decrease at the 2nd power.

Very Short-rangePersonal Area Networks

ZigBee

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ZigBee

– Standard: IEEE 802.15.4– 915 MHz (40 Kbps)– 2.4 Ghz (250 Kbps)– Range: 30 to 300 feet• Extended range via mesh network

– Power: <10 microamp (sleep mode)

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ZigBee– Up to 255 nodes per network.– Very low-cost electronics (<$2).– Security was not part of original specification.– Latest spec includes three levels of security.–Minimal hardware requirements.

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Short-rangePersonal Area Networks

Bluetooth

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Bluetooth

– Standard: IEEE 802.15.1– 2.4 GHz – Range: 3 - 300 feet ( 1 mw – 100 mw)– Data Rate: 1 Mbps (V1.2) / 24 Mbps (V4.0)– Power: <100 microamp (sleep mode).– Up to 7 clients form a piconet. Multiple piconets can

link to form scatternets.

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Bluetooth

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Ultra-Wideband

– Standard: None* (based on IEEE 802.15.3a)– Range: 6 to 30 feet– Data Rate: 480 Mbps at 6 feet– Data Rate: 110 Mbps at 30 feet

*IEEE UWB committee disbanded at meeting in Hawaii January 19, 2006.

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Technology Comparison

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Metro or CampusWiMAX

(Wireless MetropolitanArea Networks)

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WiMAX– Standard: 802.16 (point-to-point)– Standard: 802.16a (omnidirectional)– Standard: 802.16e (mobile)– Range: ~30 miles– Data Rate: 70 Mbps (typ)– Frequency: 10 – 60 GHz (802.16)– Frequency: 2 – 11 GHz (802.16a)

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Point-to-Point:Microwave & Laser

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Microwave Systems

Microwave– Range 2 to 30 miles depending on frequency.• 2 miles at 30 GHz - 30 miles at 2 GHz

–Multiple channels.• Modular systems add bandwidth as needed.• 4 T1 circuits plus analog video.

– License required, but easily obtained.• Frequency coordination required.• Frequencies relatively easy to get.

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Microwave Systems– Cost effective at about $30,000 per link, installed.– No preventive maintenance.– Subject to signal fade, ice, rain, etc.

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Laser Systems

Laser

– Highest bandwidth available• Multiple T3s to 155 Mbps ATM• OC-3 (155 Mbps) to OC-48 (2.488 Gbps)

– 1,000 meter range– No license required– Cost effective at about $20,000 per link, installed

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Laser Systems

– Requires preventive maintenance– Subject to vibration, heat distortion, blocking by

sunlight, etc.– Also known as Free Space Optical Networking

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Infrared Wireless Technology

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Infrared• Historical note: Many wireless networking technologies

had an infrared interface, but it is rarely ever implemented.

• Once common on printers and laptops (the little ruby-red window).

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The Alphabet Soup of Wireless Networking

Standards

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Wireless Standards

–802.1x Extensible Authorization Protocol–802.11a 54 Mbps at 5 GHz–802.11b 11 Mbps at 2.4 GHz–802.11d International freq. coordination–802.11e Quality of Service–802.11f Access Point Interoperability–802.11g 54 Mpbs at 2.4 GHz–802.11h Frequency and power control for 802.11a

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Wireless Standards

–802.11i Enhanced security and encryption–802.11k Advanced radio resource mgmt–802.11n 2.4 and/or 5 GHz band

Multiple input/Multiple output (MiMo) 100 – 200 Mbps data rate–802.11p 5.9 GHz automotive direct short-range

communications

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Wireless Standards

–802.11r Fast roaming between APs–802.11s Extended Service Set (Mesh)–802.11u Internetworking

(e.g., WiFi to cellular)–802.11v Wireless network management–802.11w Protected management frames–802.11x User-authentication

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Wireless StandardsToday’s Technology

–802.11ac 5 GHz1 Gbps aggregate data rate–802.11ad 60 GHz

6+ Gbps (very short range)

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Wireless StandardsTomorrow’s Technology

– 802.11af (Approved Feb. 2014)• “White-Fi” “Super WiFi”• Utilizes empty (“white space”) TV channels

between 54 and 790 MHz• Cognitive radios detect and avoid

interference with other uses• 26 – 570 Mbps

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Wireless StandardsTomorrow’s Technology

– 802.11ah (March 2016)• Utilizes frequencies below 1 GHz for

increased range and reduced power consumption

• 1 Kilometer range• M2M communications

– 802.11ax• Will replace 802.11ac• 4X data rate of 802.11ac

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Wireless Standards

–802.15 Personal Area Networks–802.16 Broadband wireless local access.

• “Last mile” access in competition with telephone and cable service providers.

–802.20 Mobil Broadband Wireless Access• Low latency (< 20 ms).• Realtime data rates up to 1 Mbps at 150 MPH• Porsche has done field trials of 1 Mbps at 206 MPH.

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General Design Considerations

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Design IssuesWe Have Control Of

l Suitable frequency or service l Coverage (area)l Capacity (simultaneous users)l Bandwidth (applications)l Transmitting power (may be regulated)l Channel selectionl Cabling: two Cat. 6, UTP or one Cat 6A, UTP?l Electric powerl Signal securityl Physical security

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Design IssuesWe Don’t Have Control Of

�Other users (same service or frequency)�Building construction�Signal reflection, deflection, refraction, etc.�Rouge users

(if no or weak security)�Rouge WLAN access points

(if access control not used)

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TerminologyDecibel: Gain (increase) or loss (decrease) of signal strength measured as a ratio against a standard.The ratio is expressed mathematically as:

dB = 10 log10 (P1/P2)Example: log10 (100/10) = 2

10 (2) = 20 dB

Common (power) dB values to remember are:�3 dB = times 2 increase or 1/2 decrease�6 dB = times 4 increase or 1/4 decrease�20 dB = times 10 increase or 1/10 decrease

Terminology

Attenuation: Signal loss caused by transmission through a wire, the air, or objects located between the transmitter and the receiver.

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TerminologyAttenuation: Radio signals traveling through free space are attenuated according to a “square law” formula.

Signal strength = q/r2

Where q = signal source and r = distance from the source.

Double the distance and the signal decreases by a factor of 4 (1/4 of its prior value).

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Signal Path ModelPr = (Pt)(Gt)(Gr)(l/4πd)2

Where:Pr Received powerPt Effective radiated powerGt Antenna gainGr Receiver gainλ wavelength in metersπ pi (3.1415962…..)d distance in meters

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Path Loss CalculationPath LossdB = 20 log (4l/π)+10 log (dn)

Where:λ wavelength in metersπ pi (3.1415962…..)d distance in metersn =2.0 free space2.7 to 3.5 outdoor urban areas3.0 to 5.0 shadowed outdoor urban areas1.6 to 1.8 in-building, direct line-of-sight3.0 to 3.5 in-building, fabric covered partitions4.0 to 6.0 in-building, obstructed, office2.0 to 3.0 in-building, obstructed, warehouse

Terminology

Common Building MaterialsAttenuation at 2.4 GHz

(all values are approximate)Glass (non-tinted) -2 to -3 dBWood door -3 dBSystems furniture -3 to -5 dBDry wall (sheetrock) -3 to -4 dBMarble -5 dBBrick -8 dB to -10 dBConcrete (floor/wall) -10 to -15 dB

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Path Link BudgetPr = Pt + Gt + Gr – Path loss - Lr

Where:

Pr Received powerPt Effective radiated powerGt Antenna gainGr Receiver gainLR Receiver loss (noise figure)*

*A common specification for receiver sensitivity is -93 dB.That is, the signal at the receiver must be at least -93 dB to be detected.

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WiFi

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Site Survey Reports

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WiFi Performance

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Heat maps are thetip of the iceberg

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Applications!

ShieldingMultipath Distortion

Intermodulation ProductsRF Front-end Desensitizing

Calculating Signal Strength Is Only The Beginning !

WiFi Performance

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WiFi Performance

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WiFi Performance

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WiFi Performance

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WiFi Performance

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WiFi Performance

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Bit Rate vs. Sensitivity

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QAM Decoding

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EVM = Error Vector Magnitude

QAM Constellations

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WiFi Performance

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Access Point PlacementDesign Tool

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Access Point PlacementDesign Tool

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A large coffee mug is about theright diameter for spacing access points

on 1/16” scale drawings1 coffee cup = 1 access point

WiFi PerformanceStandard Freq. Typ. Data

RateMax. Data

Rate802.11a 5 GHz 25 Mbps 54 Mbps

802.11b 2.4 GHz 6.5 Mbps 11 Mbps

802.11g 2.4 GHz 25 Mbps 54 Mpbs

802.11n 2.4/5 GHz 200 Mbps 540 Mbps

802.11ac 5 GHz 30 Mbps -1 Gbps

78 Mbps –3.2 Gbps*

802.11ax 2.4/5 GHz TBD Target4X 11ac

72*NBASE-T Alliance for 2.5/5 Gbps Ethernet on Cat. 5e and 6 over 100 meter channel

Rules of Thumb

• Conservative design assumptions suggest:• 802.11b: 100’ radius for 11 Mbps• 802.11a: 50’ radius for 54 Mbps• 802.11g: 50’ radius for 22/54 Mbps• 802.11n: 50’ radius for 100 Mbps• 802.11ac: 30’ radius for 1 Gbps+• Building materials, contents and interference have a

drastic effect on range and useable bit rate.

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Fire Hose vs. Soda Straw

802.11ac WAPs

2 Cat. 6 or 1 Cat. 6ALegacy edge

switches

Legacy 10 GbpsBackbone

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WLAN Antennae

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WiFi Antenna Placement

• Rough Rules of Thumb– Doubling the height of an antenna has approximately

the same affect as increasing transmitter power by a factor of 10.

– BUT doubling the height of an antenna or increasing transmitting power by a factor of ten does not double the coverage area. As a rule of thumb, reliable operating range increases by approximately 30%.

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Antenna Patterns

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Non-directional antenna

Directional antenna

Antennas Types

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Omni-directional Ceiling Antenna

Directional YAGI Antenna

“Rubber Ducky”™flexible antenna

Slotted Coaxial CableFaceplate Antenna

Ceiling Tile Antenna• Armstrong iCeiling Product Line– Dual-band cellular + WiFi

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Flat-panel Antenna

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Specialized Technology

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16 antennae (22.5 degrees per sector)16 radios1,000 users1 GB Ethernet

Point-to-Point Antennae

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Tech Tools

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Tech Tools

• Xirrus WiFi Inspector• http://www.xirrus.com/resources/free-tools/wi-fi-

inspector/

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Tech Tools

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Tech Tools

• Metageek Wi-Spy• http://www.metageek.com/

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Tech Tools

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Build Your Own

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• Compliance with FCC part 95 (MURS)• Standard frequency 154.570MHz or 154.600MHz (re-programmable)• Other frequencies from 120MHz to 175MHz• Data rates up to 5kbps for standard module• Usable range over 1km• Fully screened• Low power requirements• 25kHz Channel spacing• Feature-rich interface (true analogue and/or digital baseband)

Build Your Own

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http://www.bb-elec.com/Products/Wireless-Cellular.aspx

Build Your Own

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Build Your Own

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Wireless Trivia

Which female Hollywood star invented spread spectrum technology and received patent #2,292,387 on Aug. 11, 1942?(Technology first used during the 1962 Cuban missile crisis)

Born in Austria Dropped out of schoolMarried six timesWorked with composer George AntheilMs. Hedwig Eva Maria Kiesler

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Wireless Trivia

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Doubleday 2011

ISBN 978-0-385-53438-3

272 pages

US $26.95 (list)

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To Learn More

2600: The Hacker Quarterlywww.2600.com

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To Learn More

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Ernest SchirmerSenior EngineerVanderweil Engineers101 Grovers Mill Road, Ste 301Lawrenceville, NJ 08648646-312-6873eschirmer@vanderweil.comwww.vanderweil.com

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