RF and Radio Technology Fundamentals by Ge3i9YVU

VIEWS: 29 PAGES: 51

									                    pptlinks.com




   RADIO FREQUENCY (RF) AND
   RADIO TECHNOLOGY
FUNDAMENTALS




                                   April 2008
                                    pptlinks.com




POINT TO POINT (PTP)

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




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
                                                              pptlinks.com




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
                                 pptlinks.com



THE LINE-OF-SIGHT ISSUE - RAISING ONE SIDE

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



THE LINE-OF-SIGHT ISSUE – RAISING TWO SIDES

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


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)
                                  pptlinks.com



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)
                                                     pptlinks.com




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
                              pptlinks.com




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
     2 Radians = 360°
                                0°      180°    360°
     57.3° = 1 Radian



                                             270°
                                              pptlinks.com




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
                                   pptlinks.com



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
                    pptlinks.com




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
                                   pptlinks.com




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
                                             pptlinks.com


 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)
                                            Signal is more concentrated
                        Point A   Point B   at Point A than at Point B
                                     pptlinks.com




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
                                pptlinks.com




RECEPTION:RF ~ VISION:LIGHT

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

     Angle   of attack
     Focus

     Obstructions

     Weather
                        pptlinks.com


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
                                pptlinks.com




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’
                                pptlinks.com




THE IMPORTANCE OF SIGNAL PHASE

   Best Case: Even number of ½ Wavelengths
    x
      _

                          2x
                                _
    -x
         _

             +       =
    x
         _
                          -2x
                                _

    -x   _
                             pptlinks.com




THE IMPORTANCE OF SIGNAL PHASE

   Worst Case: Odd number of ½ Wavelengths
     x
       _


    -x
         _

             +       =
    x    _


    -x   _
                              pptlinks.com




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
                                            pptlinks.com




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
                                             pptlinks.com




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
            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 integrity
            of the direct signal
                                      pptlinks.com




    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
                                                 pptlinks.com




    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
    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
                                                 pptlinks.com



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
                                                         pptlinks.com




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
            Can provide unbalanced communications when desired (e.g. more download
             than upload, or variable to demand)
            Has an impact on latency
                                                pptlinks.com



ONE-PIECE AND TWO-PIECE CONSTRUCTION
   For Proxim’s 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                                          2-piece configuration
             (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                           1-piece configuration
                                            pptlinks.com



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
  connected instead
 Some Proxim products do not have a built-in
  antenna
     an   “external” antenna must be connected
     Connected Antenna Configurations   Connectorized Antenna Configurations
                                                pptlinks.com




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



           Click here to watch the antenna properties video
                           pptlinks.com




ANTENNA PERFORMANCE PARAMETERS

 Gain
 Beamwidth/Coverage Pattern

 Polarization
                                       pptlinks.com



EFFECTIVE ISOTROPIC RADIATED POWER (EIRP)

   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



                        Radio
                    (Output Power)
                              pptlinks.com




WHAT GOVERNS DISTANCE OR COVERAGE?
 The radio’s technology (sometimes)
 The “strength” of the transmitted signal
 The radio’s ‘threshold’ specifications
 The radio’s frequency of operation
 Output power regulations
 Obstacles between the end points
 Climate/Terrain
 The antenna pattern
                                pptlinks.com


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



Transmission                                   Transmission
  Line (Loss)                                  Line (Loss)
                          RSL

          Radio                           Radio
      (Output Power)                   (Threshold)
                           UNDERSTANDING “SYSTEM
                           GAIN” & “FADE MARGIN”

   System Gain
                                   Output
     The difference               Power

      between the output
      power and the
      threshold
                                             System
   Fade Margin                               Gain

     The difference
               Received Signal Level (RSL)
      between the received                      Fade
      signal level and the                     Margin

      threshold                 Threshold
                                    pptlinks.com




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
                                                         pptlinks.com




OVERALL SPECTRUM
            AM
          Radio          UHF TV         Remote Controls
      550 - 1700kHz    460-600MHz       100GHz-500THz Medical X-ray



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



              FM Radio
   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
                                                         pptlinks.com




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
                                                                               pptlinks.com


BANDS AND REGULATIONS
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
                                                                      pptlinks.com


BANDS AND REGULATIONS
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                       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
                                                        pptlinks.com


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
       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
                                                                 pptlinks.com


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
                                                                     pptlinks.com


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
                                                                        pptlinks.com


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
                                                         pptlinks.com




    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
            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
                                                        pptlinks.com




    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
                                               pptlinks.com


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!
                    pptlinks.com




REFERENCES

www.pptlinks.com

								
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