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Wireless Communication Basics

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Page 1: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Wireless Communication Basics

Page 2: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Basics• Basic Communication System

– Transmitter and Receiver

Transmitter Receiver

Page 3: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsBasic Communication System

– Transmitter and Receiver– Transmitting Antenna

Transmitter ReceiverAntenna 1

Page 4: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsBasic Communication System

– Transmitter and Receiver– Transmitting Antenna– Receiving Antenna

Transmitter ReceiverAntenna 1 Antenna 2

Page 5: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsBasic Communication System

– Transmitter and Receiver– Transmitting Antenna– Receiving Antenna– Environment

Transmitter ReceiverAntenna 1 Antenna 2

Environment

Page 6: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsMaximizing Range

Transmitter ReceiverAntenna 1 Antenna 2

Page 7: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Essentials

Maximizing Range– Increase Transmitter (TX) Power

• Government Regulated• Low-powered Applications

Increase Power ReceiverAntenna 1 Antenna 2

Page 8: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF EssentialsMaximizing Range

– Increase Transmitter (TX) Power– Increase Receiver (RX) Sensitivity

• Specified in dBm• Every 6 dB doubles the range LOS• Every 12 dB doubles range indoors / urban

environments

IncreasePower

ImproveRX Sensitivity

IncreaseGain

IncreaseGain

Page 9: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsMaximizing Range

– Increase Transmitter (TX) Power– Increase Receiver (RX) Sensitivity– Increase Antenna Gain

• More gain equates with more focusing of energy• Antenna cables should be as short as possible

IncreasePower

ImproveRX Sensitivity

IncreaseGain

IncreaseGain

Page 10: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Basics

Basic Communication System– Transmitter and Receiver– Transmitting Antenna

• Focused energy

Page 11: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Basics

Basic Communication System– Transmitter and Receiver– Transmitting Antenna– Receiving Antenna

• Focused energy

Page 12: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Basics

Antenna Gain– Government-imposed power

restrictions– Omnidirectional

Page 13: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Basics

Antenna Gain– Directional

Page 14: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsMaximizing Range

– Increase Transmitter (TX) Power– Improve Receiver (RX) Sensitivity– Increase Antenna Gain– Clear the Environment of obstructions

• Visual (Linear) line-of-sight vs. RF (Radio) line-of-sight

IncreasePower

ImproveRX Sensitivity

IncreaseGain

IncreaseGain

Clear theEnvironment

Page 15: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Basics

Fresnel Zone– Football-shaped path

FresnelZone

Page 16: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsFresnel Zone

– Football-shaped path– Acceptable = 60% of Zone 1 + 3 meters– Raise antennas to help clear the zone

Page 17: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF Basics

Fresnel Zone– Football-shaped path– Acceptable = 60% of Zone 1 + 3 meters– Raise antennas to help clear the zone– Formula

Page 18: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

RF BasicsFresnel Zone Diameters

RangeDistance

868 MHz ModemsRequired Fresnel

Zone Radius

2.4 GHz ModemsRequired Fresnel

Zone Radius

1 m 0,29 m 0,18 m

3 m 0,51 m 0,31 m

10 m 0,93 m 0,56 m

30 m 1,61 m 0,97 m

100 m 2,94 m 1,77 m

300 m 5,09 m 3,06 m

1600 m 11,76 m 7,07 m

8000 m 26,29 m 15,81 m

16000 m 37,18 m 22,36 m

Page 19: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Importance of Frequency Selection

• Geographic Deployment– Worldwide versus Regional

• RF Performance– Range– RF Penetration– Antenna Considerations

Page 20: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

License-Free Bands

2.4 GHz

315 MHz420 MHz900 MHz5.7 GHz

900 MHz433 MHz

433 MHz868 MHz5.7 GHz

915 MHz

Page 21: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Regulatory Bodies

• FCC (United States)• IC (Canada)• ETSI (Europe, some APAC)• C-Tick (Australia• Telec (Japan)• Anatel (Brazil)

Page 22: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Rates and Ranges

Range

Pe

ak

Da

ta R

ate

Closer Farther

Slo

wer

Fas

ter

UWB Wireless Data Applications

Wireless Video Applications

IrDA

802.11g

802.11b

802.11a

2.5G/3G

Bluetooth™

ZigBee™Data

Transfer

Wireless Networking

Wi-Fi®

Cellular

Page 23: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

NodesNodes and Rates

Page 24: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

• Modem– Modulate / Demodulate

Radio Modem Operation

Page 25: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

ModulationWhat is modulation?

– The process by which a parameter (amplitude, frequency or phase of a sinusoidal signal) of a higher frequency carrier wave is altered in accordance with the baseband message signal.

– Transforms the message signal into a form that is suitable for transmission over the channel.

– The transmitter uses the baseband message signal to modulate a carrier and transmit it over the channel.

Page 26: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Radio Modem OperationTwo types of spread spectrum used in modern

Radios

1.FHSS- Frequency Hopping Spread Spectrum• Transmitter rapidly hops from one channel to the

next in a pseudo-random fashion, avoiding long-term interference.

• Receiver follows transmitter• Some Digi Products use FHSS

– 24XStream 2400 2480

Page 27: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

• Price-to-Performance Value

• High Receiver Sensitivity

• Low Power Consumption

• FCC (U.S.A.), IC (Canada), • ETSI (Europe) Approved

XStreamKey Features

Best Value OEM RF Modules 2.4GHz

Page 28: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

XStream (2.4 GHz)Best Value OEM RF Modules

Specifications

Indoor/urban Range up to 180 m

Outdoor line-of-sight Range up to 16 km

Transmit Power Output 50 mW (17 dBm)

Receiver Sensitivity -105 dBm @9600 bps

Operating Frequency 2.45-2.46 GHz

Operating Voltage 5V (OEM) 7-18 (Boxed)

RF Data Rate 9600 or 19200 bpsInterface Packages Available

Page 29: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Radio Modem OperationTwo types of spread spectrum used in modern Radios

2. DSSS- Direct Sequence Spread Spectrum• Each bit is represented by N, shorter segments, called chips.• Increases over-the-air rate by a factor of N, widening the spectrum• Correlator in receiver examines the chips and maps chips back to bits,

while simultaneously spreading undesired signals• Processing gain, 10*log(chip_rate/bit_rate)• Some Digi products

use DSSS– XBee– XBee-Pro– All WiFi

enabledproducts

Page 30: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Digi RF Products Packaged (Boxed)

Modules (Embedded)

Page 31: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

DigiRF Products

• XBee• XStream• XTend• XPress• XCite• Digi Mesh

Page 32: Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

Product Name Frequency Power OutputIndoor RangeOutdoor Range

Data Rate

XBee 2.4 GHz 1 mW 30 meters100 meters

250 Kbps

XBee-PRO 2.4 GHz 10 mW19 mW (EIRP)

80 meters800 meters

250 Kbps

9XTend 900 MHz 1 Watt 900 meters64 kilometers

115 Kbps

9XStream 900 MHz 100 mW 450 meters32 kilometers

19.2 Kbps

24XStream 2.4 GHz 50 mW 180 meters16 kilometers

19.2 Kbps

9XCite 900 MHz 4 mW 90 meters300 meters

38.4 Kbps

Digi RF Modules