rf and radio technology fundamentals

8/2/2019 RF and Radio Technology Fundamentals

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WAN Basics

Tsunami MP.11 - QB.11 QuickBridge 60250

Radio Frequency (RF) and

Radio Technology Fundamentals

April 2008


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Unwiring the Network

One location to one location

Dedicated access

Full bandwidth between two locations

Point to Point (PtP)


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Point-to-Multipoint (PMP)

One location to many locations;Many locations to one location

Shared access

Shared bandwidth between multiple locations

Outdoor Point-to-Multipoint

Indoor Wireless LAN


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The Concept of Line-of-Sight

(LOS)

No obstructions between each end No trees

No buildings

No mountains Can you go through a window?

Probably, but with added losses that are hard to predict:

Plan on 10dB as an initial guess,can be greater for reflective (metallic) tinted glass

Note: The lower the frequency, the better it will travel through obstacles


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The Line-of-Sight Issue -

raising one side

A structure can be erected to establish line-of-sight over obstacles


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The Line-of-Sight Issueraising two sides

Two structures can be erected to establish line-of-sight over obstacles


7/50Unwiring the Network

The Line-of-Sight Issueusing a repeater

A system approach called a repeater can establish line-of-sight to goaround or over obstacles

Active repeaters (two radio systems back-to-back)

Passive repeaters (one radio system redirected)



time

period

(cycle)

The Hertz Measurement of

Frequency

1 Hertz (Hz) = 1 cycle/second 1,000 Hz = 1 kHz

1,000,000 Hz = 1 MHz

1,000,000,000 Hz = 1 GHz



Wavelength

A B

Inversely proportional to the frequency

Wavelength = the distance required to complete one cycle at a particular

frequency

The distance from Point A to Point B represents one wavelength

Wavelength is normally measured relative to meters (such as cm, or mm)



Phase

The location of the traveling wave at a fixed point in time

Measured in degrees or radians, related to Pi ()

360 Degrees = 1 Cycle

2 Radians = 360

57.3 = 1 Radian

0

90

180

270

360



Modulation

Method of sending information over radio wave By changing the signal phase over time

one can send information

Example QPSK (Quadrature Phase Shift Keying): 4 decisions points

2 code bits per symbol

64 QAM (Quadrature Amplitude Modulation) 64 decision points

6 coded bits per symbol

90

0

270

180
http://upload.wikimedia.org/wikipedia/commons/8/8f/QPSK_Gray_Coded.svg



Watts & Decibels:

Measurement of Power

Watt (W)

Decibel reference to 1 mW (dBm)

Decibel (dB) - a ratio or difference in power

e.g. 20dBm is 3dB less than 23dBm

+3 dB equals power x2 +10 dB equals power x10

Conversion equations

x(dbm)=10logy(mW)

y(mW)=10x(dBm)/10



1 W

2 W

10 W

30 dBm

33 dBm

40 dBm

100 W 50 dBm

100 mW 20 dBm

1 mW 0 dBm

Watts vs. dBm

100 uW -10 dBm

0.001 nW -80 dBm



Power and Directivity

Without obstructions and with high intensity and beam focus, RF can travellong distances

Power is measure of strength

Gain is measure of amplification

Mi B h Si il t



Microwaves Behave Similar to

Visible Light & Sound

They propagate in air similar to light and sound Reflect off surfaces

Absorbed by surfaces

Diffuse and refract through substances

Transmitting source

(e.g., car headlight)

Point A Point B

Signal is more concentrated

at Point A than at Point B



RF Refraction and Scattering

RF can pass through materials which will change its direction of travel(called refraction)

RF can pass through materials which will diffuse the energy (scatter)

to a wider beam

Air (medium 1)

ApparentPosition

ApparentPosition

Actual PositionActual Position

Water (medium 2)Water (medium 2)

Away fromPerpendicular

Observer



Reception:RF ~ Vision:Light

Reception of RF can be affected by vision-related components Blinders

Angle of attack

Focus

Obstructions

Weather

Ob t ti Will St



Obstructions Will Stop or

Seriously Attenuate Signals

Some RF can travel easily throughwalls, stone, etc. and some will be

immediately dampened

Partial obstructions can dramatically

reduce wave energy



RF is Attenuated by Rainfall

Signals above 11 GHz can beseverely affected

Most of Proxims products operate

below 6 GHz and are virtually

unaffected by rainfall in most parts

of the world=7dB/mile

11GHz

Cloudburst

6GHz

Cloudburst


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RF Reflection and Multipath

RF can bounce off objects likebuildings and mountains, water and

atmosphere

Different paths of RF will arrive at

destination at different times - this is

called multipath

Th I t f Si l


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The Importance of Signal

Phase

Best Case: Even number of Wavelengths

+ =

_

_

_

_

_

x

-x

x

-x

-2x

2x_



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Phase

Worst Case: Odd number of Wavelengths

+ =

_

_

_

x

-x

x

-x

_


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Fresnel Zone

The Fresnel zone is additional path clearance that is required to optimizeradio reception

There are an infinite number of points where reflected signal arrives exactly

wavelength out of phase for a given frequency


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Earth Curvature and k factor

One factor for line-of-sight includes earth curvature and the effects of theatmospheric refraction due to the curve of the earths surface

The earths bulge between the end points must be considered when determining if

LOS and proper path clearance exists, including Fresnel zone

The k factor (refraction index) is a mathematical figure that will help determine the

effect on path clearance

Not much of a factor under 10 miles


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Polarization

Polarization describes the orientation of the E (electrical) and H (magnetic)components of an RF wave front.

Linear polarization (horizontal, vertical, slant linear)

Circular polarization (right-hand, left hand)

RF can be transmitted (and received) with dominant polarization

Polarization provides a level of discrimination (attenuation) against differentpolarization signals, especially opposite polarization (e.g. horizontal versus

vertical)

Weather and multipath can de-polarize RF


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Terrain Effects on RF

Mountainous terrain is best

Many multipath reflections will not

reach the other end, thus reducing

the potential for out-of-phase

reflected signals that may have

degraded the integrity of the direct

signal

Flat, smooth terrain is worst

Many multipath reflections may reach

the other end, thus increasing the

potential for out-of-phase reflected

signals that may degrade the integrityof the direct signal


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Climate Effects on RF

Humid climate is worst More moisture = more ducting and refraction = more attenuation

Dry climate is best

Reduced moisture = less ducting and refraction = less attenuation


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The Concept of Interference

Interference is the reception of signals from sourcesother than the intended source

The source of the interference may be from a closer and/or

stronger signal level compared to the desired signal impacting

the ability of the system to receive the desired signal properly

Interference can be caused by energy that is at the same frequency as the

signal that you wish to receive, or can be at a nearby frequency with enough

energy to leak into the receiver

Interference can also be caused by energy that is a completely different

frequency from that which you wish to receive. High-powered transmitters can

radiate harmonics where they are also inadvertently transmitting energy that

is a multiple of the intended transmitter frequency

The Basics of Interference


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The Basics of Interference

Management

Use opposite antenna polarization to reject nearby interference Change frequency plans to steer around interference

Swap ends of the system so that the receive frequency is changed (where

possible)

Change frequency channels or bands (where possible)

Move antenna to attenuate interference

Create physical blocks (hide) the antenna from the interference source

Moving the antenna may create a new angle from the interference, which may

greater reject the interference

Use larger or high-performance antennas (where possible)

Improves off-angle rejection

Improves gain of on-angle signals

Methods of Two-Way


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Methods of Two-Way

Communications

Frequency Division Duplex (FDD) Communications in one direction are at a different frequency than in the other

direction, transmitting and receiving in both directions at the same time Can establish high speeds in both directions (usually equivalent speed)

No substantial time delays (latency) for communication, as no information is buffered

The difference in frequency can be small (a few MHz) or large (100s of MHz), in the same

frequency band or different bands altogether

Time Division Duplex (TDD or Ping Pong)

Communications in one direction are at a different time than in the other direction,

transmitting and receiving at the same frequency but in succession Can provide unbalanced communications when desired (e.g. more download than upload, or

variable to demand)

Has an impact on latency

One-Piece and Two-Piece


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One-Piece and Two-Piece

Construction

For Proxims outdoor wireless solutions,one end of the radio system is made up

of one or two distinct boxes

One-piece radios Indoor Are designed for all-indoor mounting

(or mounting in a weatherproof container)

One piece radios Outdoor Rugged housing

Two-piece radios give the flexibility of mounting part of the

system closer to the antenna and part inside

2-piece configuration

1-piece configuration

Connected or Connectorized


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Connected or Connectorized

Antenna

Some Proxim products have built-in antennas that cannot be removed orbypassed

Some Proxim products have built-in antennas that can be bypassed and an

alternate antenna connected instead

Some Proxim products do not have a built-in antenna

an external antenna must be connected

Connected Antenna Configurations Connectorized Antenna Configurations


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Understanding Antennas

Click here to watch the antenna properties video

Outdoor systems usually implement directional antennas Highly directional (narrow beamwidths) for PTP systems

Sector (wide beamwidths) for the central location of PMP systems

Somewhat directional (medium beamwidths) for the client locations of PMP systems

The choice of gain and beamwidth is critical to the application

The larger the antenna (in surface area), the higher the gain

The lower the gain, the wider the beamwidth

The wider the beamwidth, the more susceptible to interference

The higher the gain, the further the distance and/or improved RSL

The configuration of polarization is important to the system plan

To optimize communications, both ends of a wireless system should be implementedwith the same polarization

Antenna Performance
http://var/www/apps/conversion/current/tmp/scratch23661/C:/Documents%20and%20Settings/ajayksin/Local%20Settings/Temp/Antenna%20Properties.WMVhttp://var/www/apps/conversion/current/tmp/scratch23661/C:/Documents%20and%20Settings/ajayksin/Local%20Settings/Temp/Antenna%20Properties.WMV


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Antenna Performance

Parameters

Gain Beamwidth/Coverage Pattern

Polarization

Effective Isotropic Radiated


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Effective Isotropic Radiated

Power (EIRP)

The output power of a transmitter, including all cable losses and antennagains

Transmitter Output Power - Cable Loss + Antenna Gain

TransmissionLine (Loss)

Antenna

(Gain)

Radio(Output Power)

EIRP

What Governs Distance or


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What Governs Distance or

Coverage?

The radios technology (sometimes) The strength of the transmitted signal

The radios threshold specifications

The radios frequency of operation

Output power regulations

Obstacles between the end points

Climate/Terrain

The antenna pattern

Basic Distance Planning:


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Antenna(Gain)

Radio(Threshold)


Antenna(Gain)

Path(Loss)

Basic Distance Planning:

a series of Gains and Losses

Radio(Output Power)

RSL

Understanding System Gain


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OutputPower

Threshold

SystemGain

Understanding System Gain

& Fade Margin

Received Signal Level (RSL)Fade

Margin

System Gain The difference between the output

power and the threshold

Fade Margin

The difference between the received

signal level and the threshold

U d t di A il bilit


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Understanding Availability

The predicted amount of time the system will be operating above threshold Availability is the primary design criteria for outdoor wireless systems

Examples:

99.999% = 5.26 minutes/year outage



O ll S t


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VLF LF MF HF UHF SHFVHF EHF Infrared Visible UV GammaX Cosmic

Sound20Hz - 20kHz

AMRadio

550 - 1700kHz

FM Radio88-108 MHz

VHF TV

54-220 MHz

UHF TV460-600MHz

Cellular 800-900 MHzPCS 1.8-2 GHz

Terrestrial Microwave 118 GHzIndoor Wireless 900 MHz, 2 & 5 GHz

Remote Controls100GHz-500THz

Light700THz - 1000THz

Overall Spectrum

Medical X-ray

T f S t


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Types of Spectrum

License-exempt Anyone can use

No coordination or registration required

Opportunity for interference, which the user must work around

Licensed (or Leased)

Coordination required

Registration required

Interference is better controlled, but not completely eliminated Regulatory agency will assist with any interference cases

Owned

Purchased spectrum, usually in a given region, usually by auction Owner needs to self-coordinate intra-system interference potential

Some coordination may be needed with neighboring owners

Bands and Regulations


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USA and Canada

900 MHz ISM 902 928 MHz

+36 dBm EIRP. For every dB of antenna gain above 6dBi, Tx must be reduced by 1 dB

1.8 GHz Federal Government

1.755 1.850 GHz +80 dBm EIRP

2.4 GHz ISM

2.4000 2.4835 GHz +36 dBm EIRP. For every 3 dB of antenna gain above 6dBi, Tx must be reduced by 1dB

+36 dBm EIRP for PMP systems and some PtP systems

3.6 GHz

3.650 3.700 GHz +44 dBm EIRP (per 25 MHz) for fixed station

+30 dBm EIRP (per 25 MHz) for mobile station

An unlimited numbers of licenses will be granted,

but every base station must be registered.

established circular protection zones around existing station

150 km for Fixed Satellite Service (FSS) earth stations

80 km for Federal Government stations



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a ds a d egu at o s

USA and Canada

4.9 GHz Public Safety 4.9405 4.9895 GHz

Chanel size (Mhz) 1 5 10 15 20 For every dB of antenna

Low power (dBm) 7 14 17 18.8 20 gain

above 9dBi, Tx must

High power (dBm) 20 27 30 31.8 33 bereduced by 1 dB

5.3 GHz U-NII

5.250 5.350 GHz +30 dBm EIRP limit for all systems

5.4 GHz U-NII 5470 5725 GHz

+30 dBm EIRP limit for all systems, Automatic DFS Required

5.8 GHz U-NII

5.725 5.825 GHz +53 dBm EIRP limit for qualified PTP systems

+36 dBm for PMP systems



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g

India

2.4 GHz 2.4000 2.4835 GHz

+36 dBm EIRP, + 30 dBm Output Power

Indoor + outdoor

3.3 GHz

3.300 3.400 GHz

Licensed band

5 GHz

5.150 5.350 & 5.725 5.875 GHz

+23 dBm EIRP

Indoor (which includes usage within the single contiguous campus

of an individual, duly recognized organization or institution) 5.825 5.875 GHz

+36 dBm EIRP, + 30 dBm Output Power

Outdoor



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g

Russian Federation

Russian Federation defined four geographical zone Category I cities with population exceeding 1 million inhabitant

Category II cities with population between 250k and 1 million inhabitant

Category III cities with population between 100k and 250k inhabitant

Category IV whole Russian Federation area excluding

cities withpopulation exceeding 100k inhabitant

2.4 GHz

2.4000 2.4835 GHz Point to Multipoint systems I II III IV

BSU and SU max Tx power -10 -10 -10 -10

dBWatt

BSU and SU max EIRP -4 6 6 6 dBWatt

BSU max range coverage 0,5 4 10 20 km

Point to Point systems

Max EIRP 30



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g

Russian Federation

3.5 GHz 3.400 3.450 and 3.500 3.550 GHz

Point to Multipoint systems I II III IV

BSU and SU max Tx power -10 -10 -10 0

dBWatt

BSU and SU max EIRP -4 0 10 20 dBWatt

BSU max range coverage 3 5 10 20 km


Max EIRP 30

dBWatt

Antennas pattern According to - F.1336

or F.699 recommendations

5.2 GHz




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g

Russian Federation

5.7 GHz


BSU and SU max Tx power -10 -10 -10 0

dBWatt

BSU and SU max EIRP 0 6 13 23 dBWatt

BSU max range coverage 3 5 10 20 km


Max EIRP 30

dBWatt

Antennas pattern According to - F.1336

or F.699 recommendations

6 GHz




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g

Europe

2.4 GHz ETSI 301 328

2.400 2.483 GHz (3 channel) +20 dBm EIRP, Indoor and outdoor use.

3.5 GHz ETSI 301 021 v1.6.1 (July 2003)

3.400 3.600 GHz Licensed band

5 GHz ETSI 301 983 v1.3.1 (August 2005)

5.150 5.250 GHz (4 channel) +23 dBm EIRP, Indoor use, TPC

5.250 5.350 GHz (4 channel) +23 dBm EIRP, Indoor use, TPC, DFS

5.470 5.725 GHz (11 channel) +30 dBm EIRP, Indoor and outdoor use, TPC, DFS

5.8 GHz ETSI 302 502 v1.1.1 (November 2006)

5.725 5.850 GHz (5 channel) +36 dBm EIRP, Fixed outdoor use, TPC, DFS, UK, Norway, Germany

Extra Regulation Europe


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Extra Regulation Europe

WEEE

Waste of Electrical and Electronics Equipment

Directive 2002/96/EC

Implementation August 2005

RoHS

Restriction of Hazardous Substance

Directive 2002/95/EC

Implementation July 2006

All Proxim ORiNOCO and TSUNAMI MP.11 / MP.16 productcomply with those two rules

Outdoor Wireless Systems


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y

Require Engineering

Determine Line-of-Sight and Path Clearance

Including Fresnel Zone, k-factor, reflection point

Determine Antenna System Requirements

Meet distance, availability and fade margin requirements

Determine All Cable Types and Lengths

Analyze Interference Potential

Including any self-interference

Plan for Proper Grounding and Lightning Protection

Plan for Egress of Cables from Outdoor to Indoor

These statements are true for ANY deployment,

even across a parking lot!