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

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Presentation on theme: "Wireless Communication Basics. RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver."— Presentation transcript:

1 Wireless Communication Basics

2 RF Basics Basic Communication System –Transmitter and Receiver TransmitterReceiver

3 RF Basics Basic Communication System –Transmitter and Receiver –Transmitting Antenna TransmitterReceiverAntenna 1

4 RF Basics Basic Communication System –Transmitter and Receiver –Transmitting Antenna –Receiving Antenna TransmitterReceiverAntenna 1Antenna 2

5 RF Basics Basic Communication System –Transmitter and Receiver –Transmitting Antenna –Receiving Antenna –Environment TransmitterReceiverAntenna 1Antenna 2 Environment

6 RF Basics Maximizing Range TransmitterReceiverAntenna 1Antenna 2

7 RF Essentials Maximizing Range –Increase Transmitter (TX) Power Government Regulated Low-powered Applications Increase Power Receiver Antenna 1Antenna 2

8 RF Essentials Maximizing 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 Increase Power Improve RX Sensitivity Increase Gain Increase Gain

9 RF Basics Maximizing 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 Increase Power Improve RX Sensitivity Increase Gain Increase Gain

10 RF Basics Basic Communication System –Transmitter and Receiver –Transmitting Antenna Focused energy

11 RF Basics Basic Communication System –Transmitter and Receiver –Transmitting Antenna –Receiving Antenna Focused energy

12 RF Basics Antenna Gain –Government-imposed power restrictions –Omnidirectional

13 RF Basics Antenna Gain –Directional

14 RF Basics Maximizing 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 Increase Power Improve RX Sensitivity Increase Gain Increase Gain Clear the Environment

15 RF Basics Fresnel Zone –Football-shaped path Fresnel Zone

16 RF Basics Fresnel Zone –Football-shaped path –Acceptable = 60% of Zone meters –Raise antennas to help clear the zone

17 RF Basics Fresnel Zone –Football-shaped path –Acceptable = 60% of Zone meters –Raise antennas to help clear the zone –Formula

18 RF Basics Fresnel Zone Diameters Range Distance 868 MHz Modems Required Fresnel Zone Radius 2.4 GHz Modems Required Fresnel Zone Radius 1 m0,29 m0,18 m 3 m0,51 m0,31 m 10 m0,93 m0,56 m 30 m1,61 m0,97 m 100 m2,94 m1,77 m 300 m5,09 m3,06 m 1600 m11,76 m7,07 m 8000 m26,29 m15,81 m m37,18 m22,36 m

19 Importance of Frequency Selection Geographic Deployment –Worldwide versus Regional RF Performance –Range –RF Penetration –Antenna Considerations

20 License-Free Bands 2.4 GHz 315 MHz 420 MHz 900 MHz 5.7 GHz 900 MHz 433 MHz 868 MHz 5.7 GHz 915 MHz

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

22 Rates and Ranges Range Peak Data Rate CloserFarther Slower Faster UWB Wireless Data Applications Wireless Video Applications IrDA g b a 2.5G/3G Bluetooth ZigBee Data Transfer Wireless Networking Wi-Fi® Cellular

23 Nodes Nodes and Rates

24 Modem –Modulate / Demodulate Radio Modem Operation

25 Modulation What 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.

26 Radio Modem Operation Two 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

27 Price-to-Performance Value High Receiver Sensitivity Low Power Consumption FCC (U.S.A.), IC (Canada), ETSI (Europe) Approved XStream Key Features Best Value OEM RF Modules 2.4GHz

28 XStream (2.4 GHz) Best Value OEM RF Modules Specifications Indoor/urban Rangeup to 180 m Outdoor line-of-sight Rangeup to 16 km Transmit Power Output 50 mW (17 dBm) Receiver Sensitivity-105 bps Operating Frequency GHz Operating Voltage5V (OEM) 7-18 (Boxed) RF Data Rate9600 or bps Interface Packages Available

29 Radio Modem Operation Two 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 enabled products

30 Digi RF Products Packaged (Boxed) Modules (Embedded)

31 DigiRF Products XBee XStream XTend XPress XCite Digi Mesh

32 Product NameFrequencyPower Output Indoor Range Outdoor Range Data Rate XBee2.4 GHz1 mW 30 meters 100 meters 250 Kbps XBee-PRO2.4 GHz 10 mW 19 mW (EIRP) 80 meters 800 meters 250 Kbps 9XTend900 MHz1 Watt 900 meters 64 kilometers 115 Kbps 9XStream900 MHz100 mW 450 meters 32 kilometers 19.2 Kbps 24XStream2.4 GHz50 mW 180 meters 16 kilometers 19.2 Kbps 9XCite900 MHz4 mW 90 meters 300 meters 38.4 Kbps Digi RF Modules


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