# RF and Radio Technology Fundamentals by Ge3i9YVU

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FUNDAMENTALS

April 2008

POINT TO POINT (PTP)

 One location to one location
 Dedicated access
 Full   bandwidth between two locations

POINT-TO-MULTIPOINT (PMP)

 One location to many locations;
Many locations to one location
 Shared access
Indoor Wireless LAN
 Shared     bandwidth between multiple locations

Outdoor Point-to-Multipoint

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

THE LINE-OF-SIGHT ISSUE - RAISING ONE SIDE

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

THE LINE-OF-SIGHT ISSUE – RAISING TWO SIDES

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

THE LINE-OF-SIGHT ISSUE –
USING A REPEATER
   A system approach called a “repeater” can
establish line-of-sight to go around or over
obstacles
 Activerepeaters (two radio systems back-to-back)
 Passive repeaters (one radio system redirected)

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

time

period
(cycle)

WAVELENGTH
 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)

A         B

PHASE

 The location of the traveling wave at a fixed
point in time
 Measured in degrees or radians, related to Pi
90°

()
 360 Degrees = 1 Cycle
0°      180°    360°

270°

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

90

   64 QAM (Quadrature Amplitude Modulation)             180         0
   64 decision points
   6 coded bits per symbol
270

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

WATTS VS. DBM
100 W    50 dBm

10 W    40 dBm
2W     33 dBm
1W     30 dBm

100 mW     20 dBm

1 mW     0 dBm
100 uW    -10 dBm

0.001 nW   -80 dBm

POWER AND DIRECTIVITY

   Without obstructions and with high intensity
and beam focus, RF can travel long distances
 Power  is measure of strength
 Gain is measure of amplification

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
Signal is more concentrated
Point A   Point B   at Point A than at Point B

RF REFRACTION AND SCATTERING

 RF can pass through materials which will
change it’s direction of travel
(called ‘refraction’)
 RF can pass through materials which will
Away from
Air energy
diffuse the(medium 1) (scatter)
Perpendicular

to a wider beam
Observer

Apparent
Position
Water (medium 2)
Actual Position

RECEPTION:RF ~ VISION:LIGHT

   Reception of RF can be affected by “vision-
related” components
 “Blinders”

 Angle   of attack
 Focus

 Obstructions

 Weather

OBSTRUCTIONS WILL STOP OR SERIOUSLY
ATTENUATE SIGNALS
 Some RF can travel
easily through walls,
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 be severely
11GHz
Cloudburst
affected
=7dB/mile                  Most of Proxim’s
6GHz           products operate
Cloudburst
below 6 GHz and are
virtually unaffected
by rainfall in most
parts of the world
RF REFLECTION AND
MULTIPATH

 RF can “bounce” off
objects like buildings
and mountains, water
and atmosphere
 Different paths of RF
will arrive at
destination at different
times - this is called
‘multipath’

THE IMPORTANCE OF SIGNAL PHASE

   Best Case: Even number of ½ Wavelengths
x
_

2x
_
-x
_

+       =
x
_
-2x
_

-x   _

THE IMPORTANCE OF SIGNAL PHASE

   Worst Case: Odd number of ½ Wavelengths
x
_

-x
_

+       =
x    _

-x   _

FRESNEL ZONE

 The Fresnel zone is additional path clearance
that is required to optimize radio reception
 There are an infinite number of points where
reflected signal arrives exactly ½ wavelength
out of phase for a given frequency

EARTH CURVATURE AND K FACTOR

   One factor for line-of-sight includes earth
curvature and the effects of the atmospheric
refraction due to the curve of the earth’s surface
 The earth’s 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

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 different polarization signals, especially “opposite”
polarization (e.g. horizontal versus vertical)
   Weather and multipath can “de-polarize” RF
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
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
of the direct signal

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

THE CONCEPT OF INTERFERENCE
   Interference is the reception of signals from sources
other 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
   Interference can also be caused by energy that is a
completely different frequency from that which you wish
‘harmonics’ where they are also inadvertently transmitting
energy that is a multiple of the intended transmitter
frequency

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 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 (100’s 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
than upload, or variable to demand)
   Has an impact on latency

ONE-PIECE AND TWO-PIECE CONSTRUCTION
   For Proxim’s outdoor wireless
solutions, one end of the
of one or two distinct boxes
   Are designed for all-indoor
mounting                                          2-piece configuration
(or mounting in a weatherproof
container)
   Rugged housing
   give the flexibility of mounting
part of the system closer to the
antenna and part inside                           1-piece configuration

CONNECTED OR CONNECTORIZED ANTENNA

 Some Proxim products have built-in antennas
that cannot be removed or bypassed
 Some Proxim products have built-in antennas
that can be bypassed and an alternate antenna
 Some Proxim products do not have a built-in
antenna
 an   “external” antenna must be connected
Connected Antenna Configurations   Connectorized Antenna Configurations

UNDERSTANDING ANTENNAS
   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 implemented with the same polarization

ANTENNA PERFORMANCE PARAMETERS

 Gain
 Beamwidth/Coverage Pattern

 Polarization

   The output power of a transmitter, including all
cable losses and antenna gains
 Transmitter   Output Power - Cable Loss + Antenna
Antenna
(Gain)
Gain

Transmission
Line (Loss)            EIRP

(Output Power)

WHAT GOVERNS DISTANCE OR COVERAGE?
 The “strength” of the transmitted signal
 The radio’s frequency of operation
 Output power regulations
 Obstacles between the end points
 Climate/Terrain
 The antenna pattern

BASIC DISTANCE PLANNING:
A SERIES OF GAINS AND LOSSES
Antenna     Path       Antenna
(Gain)    (Loss)       (Gain)

Transmission                                   Transmission
Line (Loss)                                  Line (Loss)
RSL

(Output Power)                   (Threshold)
UNDERSTANDING “SYSTEM

   System Gain
Output
 The difference               Power

between the output
power and the
threshold
System

 The difference
signal level and the                     Margin

threshold                 Threshold

UNDERSTANDING “AVAILABILITY”
   The predicted amount of time the system will
be operating above threshold
is the primary design criteria for outdoor
 Availability
wireless systems

   Examples:
 99.999%        = 5.26 minutes/year outage
 99.995%        = 26.28 minutes/year outage
 99.950%        = 262.8 minutes/year outage

OVERALL SPECTRUM
AM
550 - 1700kHz    460-600MHz       100GHz-500THz Medical X-ray

VLF    LF   MF   HF   VHF   UHF   SHF   EHF   Infrared      Visible     UV   X   Gamma   Cosmic

Sound     88-108 MHz                              Light
20Hz - 20kHz   VHF TV                           700THz - 1000THz
54-220 MHz

Cellular 800-900 MHz
PCS 1.8-2 GHz
Terrestrial Microwave 1–18 GHz
Indoor Wireless 900 MHz, 2 & 5 GHz

TYPES OF SPECTRUM
   Anyone can use
   No coordination or registration required
   Opportunity for interference, which the user must work around
   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
   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

BANDS AND REGULATIONS
   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                       be reduced 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
   5.8 GHz ISM
   5.725 – 5.850 GHZ
   No EIRP limit for qualified PTP systems
   +36 dBm EIRP for PMP systems and some PTP systems

BANDS AND REGULATIONS
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
   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

BANDS AND REGULATIONS
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 with           population 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                     dBWatt
Antenna’s pattern              According to МСЭ-Р F.1336
or F.699 recommendations

BANDS AND REGULATIONS
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
   Point to Point systems
Max EIRP                                   30                 dBWatt
Antenna’s pattern              According to МСЭ-Р F.1336
or F.699 recommendations

   5.2 GHz
   5.150 – 5.350 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 0         6     13       13      dBWatt
BSU max range coverage               3     6      8      8         km
   Point to Point systems
Max EIRP                                   30                 dBWatt
Antenna’s pattern              According to МСЭ-Р F.1336
or F.699 recommendations

BANDS AND REGULATIONS
RUSSIAN FEDERATION
   5.7 GHz
   5.650 – 5.725 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 0          6      13    23      dBWatt
BSU max range coverage                3   5      10     20                km
   Point to Point systems
Max EIRP                                   30                    dBWatt
Antenna’s pattern              According to МСЭ-Р F.1336
or F.699 recommendations

   6 GHz
   5.725 – 6.425 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 -10       -7       3       10      dBWatt
BSU max range coverage                3      5      10      20            km
   Point to Point systems
Max EIRP                                   30                    dBWatt
Antenna’s pattern              According to МСЭ-Р F.1336
or F.699 recommendations

BANDS AND REGULATIONS 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
   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
   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 product
comply with those two rules

OUTDOOR WIRELESS SYSTEMS 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!