Designing With Repeaters 4

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    Designing with Repeaters

    RPT 9000 Repeater

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    1. Introduction2. Why do we need repeaters. Why do we need repeaters3. Components of a repeater system4. Design objectives / criteria

    Theory and basic concepts. Theory and basic concepts6. Deployment considerations7. Design examples8. Commissioning of a repeater

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    Background THIS SHORT PRESENTATION IS A DETAILED TECHNICAL DISCUSSION ONREPEATER DESIGN. IT CONTAINS HIGH LEVEL MATHEMATICAL FORMULA FORENGINEERS AND DESIGNERSNGINEERS AND DESIGNERS.

    The telecoms companies days of massive Base Station deployment are gone

    Now its time to fine tune their networks and fill-in coverage holes andreduce dead cell zones and poor reception areas.

    Ce u ar Repeaters can a ress some coverage issues in a cost-e ective way

    This short discussion paper will cover a variety of technical considerationswhen desi nin re eaters.

    Audience This discussion paper, will aid operations personnel involved with design and

    deployment of RF repeaters. It will also help the layman understand thedesign needs when considering installing a cellular repeater

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    2. Why Use Repeaters

    Base stations

    Cell Phone Base Stations, such as those ou will normall see in a cell tower willprovide cell phone Capacity ie the number of cell phones that can be used, andCoverage, ie the total area that a particular cell tower will cover.

    Repeaters

    Are an economical way of extending coverage to an underserved area

    Extend the coverage

    Have been proven a reliable means of extending coverage

    Can be used to create a dominant pilot in an area of pilot pollution Telcosat RPT 9000 Repeater

    Can handle numerous CDMA channels (band VS channel selective)( )

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    3. Component s of a Repeater System

    Signal to and from

    distant Base Station

    BTS

    Donor Antenna

    overage an enna a so ca e rea an ennaRepeater

    New Service Area

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    Area to cover STEP 1: define the area were coverage must be improved (create a map

    based on, for example, the Received Signal Strength Indication RSSI)

    STEP 2: run a prediction using Path Profile analysis tool to see if a repeatercould theoretically address the problem area. The precise Repeater sitelocation and area to cover are re uired.

    STEP 3: analyze the results to qualify the candidate location based oncoverage objectives (STEP 1) and the ability of the signal transmission path

    .

    as required.

    Distance between donor and repeater siteAssuming line of sight between both locations, here is the equation dictating

    Free Space Loss:where: f = frequency (MHz)

    = s ance m

    Ideally, line of sight is preferred, but a repeater can sometimes be deployed inextreme conditions (obstructed path not recommended)

    . 10 10

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    Identify donor signalHere is a list of considerations for selecting a donor sector:a) Antennae azimuth discrimination: Adjust the donor antenna to peak in

    the opposite direction from the serving antenna (ideally 180). Thisshould help achieve the required isolation

    b) PN selection based on RSSI (Io) and Ec/Io. Ideally the donor signal shouldbe composed of one dominant PN (Ec/Io > -6 dB):

    Ec = RSSI + Ec/Io [this value corresponds to the received Pilotpower from the donor base station and should not vary withtime exce t in extreme weather conditions

    RSSI: This signal varies with traffic and will impact the Ec/Ioc) In general, site geometry dictates achievable antennae isolation, repeater

    coverage area and received signal strength from the donor sector

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    5. Theory and basic concepts

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    5. Theory and basic concept s

    High level link budgetWh t i it d f?hat is it composed of?

    D Donor port (repeater)

    C Coverage port (repeater)

    GDLB Radio Output Power

    PD Received signal (Donor port)PC Output Power (Coverage port)

    Radio

    PB

    PCPD

    = -= - =

    Path Loss (donor port & BTS) Repeater Output Power Repeater DownLink Gain

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    5. Theory and basic concepts

    What is Path Loss?The link budget between the output port of the radio located at the serving celland the received si nal stren th at the donor ort of the re eater. Path Loss isobtained as follows:

    A Antenna gain

    Az Antennae Azimuth Discriminationee er oss

    FSL Free Space LossOb ObstructionPL Path Loss

    B

    ADAz

    X Combining loss

    FB FDFSL

    XB

    b

    PLDB = PD - PB

    ,(donor port & BTS):

    PLDB = Gains - Losses _Gains = AB + AD Losses = XB + FB + Az + FSL+ Ob + FD

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    5. Theory and basic concepts

    Breathing of a Repeater Coverage ZoneIn CDMA, breathing is a phenomenon that can be observed on the coverage of a cell site. Arepeater is an RF device that is meant to amplify its input signal by a fixed gain. An important

    . ,limit invokes AGC to ensure the repeater does not exceed its maximum output power.Different options are to be considered when setting the gain of a repeater:

    Breathing implies: - AGC kicks in as soon as traffic increases (G is reduced)p- Ec power out of the repeater is reduced as traffic grows, thus

    reducing effective coverage area of the repeater

    - Repeater operates at maximum output power 7/24

    - Downlink gain is as follows:

    Where: Pc = Max. Output Power

    DR = Dynamic Range = 0 dB

    GDL = [PC DR] - PB - PLDB

    No breathing implies: - AGC should not be invoked- Ec power out of the repeater is fixed at any time, thus coverageis not changing

    - Repeater output power grows with traffic

    - Downlink gain remains fixed and is as follows:

    DR = Dynamic Range

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    5. Theory and basic concepts

    Breathing of a Repeater Coverage ZoneAt all times, the repeater is transmitting at full PA power. Addition of traffic reduces the

    . ,area BREATHES:

    BTS PA

    power

    Repeater

    Power= BTS wr + S stem ain

    Repeater

    Gain

    Repeater

    coverage area

    Notraffic

    RemainsFix

    Tx Pwr =Max. PA Pwr

    (No AGC)

    Tx Pwr =Max. PA Pwr

    Sometraffic

    sinvoked andgain reduced

    Full

    Tx Pwr =Max. PA Pwr

    AGC isinvoked and

    Pilot

    Traffic

    Paginggain reduced

    Sync

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    5. Theory and basic concept s

    No Breathing of a Repeater Coverage ZoneThe repeater is able to handle addition of traffic without changing the overhead output

    . ,BREATH:

    BTS PA

    power

    Repeater

    Power= BTS wr + S stem ain

    Repeater

    Gain

    Repeater

    coverage area

    Notraffic

    RemainsFix

    Max. PA Pwr

    Tx Pwr

    (No AGC)

    Max. PA Pwr

    Sometraffic

    Tx Pwr ema nsFix

    (No AGC)

    Pilot

    Traffic

    PagingFull

    Tx Pwr

    RemainsFix

    Sync(No AGC)

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    5. Theory and basic concepts

    Breathing or No Breathing ?o reat ng reat ng

    Repeater

    PA ower Grows with trafficRepeater is operating atmaximum PA ower 7/24

    Coverage areaPilot / Paging / Sync remainfixed as traffic grows.

    Pilot / Paging / Sync change astraffic grows. Coverage areavaries with traffic

    Repeater gain Remains fix Changes as traffic grows

    Dynamic range

    Sufficient PA power headroomallows for addition of traffic

    with changing the coverage

    No PA power headroom impliescoverage area changes with theaddition of traffic

    Grade of service Somewhat guaranteed Varies with traffic

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    5. Theory and basic concept s

    Noise

    Noise consists of undesired, usually random, variations that interfere withdesired signals and inhibit communications

    Noise cannot be avoided completely but its adverse effects can bereduced by various means

    Generally noise can be broken into two main categories: internal andexternal

    Internal noise originates within the communications equipment

    External noise has many possible sources

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    5. Theory and basic concepts

    Thermal Noise (NTH)

    Thermal noise power is produced by the random motion of electrons and exists

    in all conductors and resistors at any temperature above absolute zero (0K)

    Thermal noise power is calculated using temperature and bandwidth as shown by

    the equation:

    PN = k T B

    ere: N = no se power n wa s

    k = Boltzmanns constant = 1.38 x 10-23 J/o

    T = Absolute temperature in Kelvin(ambient temperature = 25C = 298K)

    B = Noise bandwidth in hertz (Hz)

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    5. Theory and basic concepts

    Thermal Noise (NTH) - formula

    Practical formula for determining bandwidth noise power is:

    =

    Where 174 dBm = NTH for a bandwidth of 1 Hz (at room temperature)

    Using this formula we can see that a CDMA channel and an AMPS channel have

    uite different bandwidth noise owers:

    Technology

    Channel Bandwidth

    (BW)

    Thermal Noise

    Power (NTH)

    CDMA 1.23 MHz -113.1 dBm

    AMPS 30 kHz -129.2 dBm

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    5. Theory and basic concepts

    Thermal Noise ()

    There are other relevant noise sources that are part of the design considerations

    Repeater manufacturers are governed as to the maximum amount of actively

    generated spurious noise the device can generate

    This s urious noise is enerall caused b inter-modulation distortion IMD

    Passive inter-modulation distortion is the effect that applying multiple tones to apass ve e emen e a sp er or an enna w ave

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    5. Theory and basic concepts

    Inter-Modulation Distortion

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    5. Theory and basic concepts

    Inter-Modulation Distortion and IP3

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    5. Theory and basic concepts

    AGCIMD, IP3 and P1dB

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    5. Theory and basic concept s

    Noise contribution

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    5. Theory and basic concept s

    -45 dBc (30 kHz)

    -45 dBc (30 kHz)

    or

    1

    2

    IS-2000 spectral mask

    -9 dBm (30 kHz)

    -55 dBc (30 kHz)P

    out 33dBm

    or

    2

    1

    2

    1

    1.23 MHz

    -22 dBm (30 kHz)

    28 dBm Pout

    < 33 dBm

    or

    -50 dBc (30 kHz)P

    out< 28 dBm

    3

    4

    3 3

    4

    -13 dBm (1 MHz)

    -13 dBm (1 kHz)9 kHz < f < 150 kHz

    4

    -13 dBm (10 kHz)

    150 kHz < f < 30 MHz

    -13 dBm (100 kHz)

    30 MHz < f < 1 GHz

    5

    f (MHz)

    -13 dBm (1 MHz)1 GHz < f < 5 GHz

    fc

    0.8

    85

    1.2

    50

    1.9

    80

    2.2

    50

    0.8

    85

    1.2

    50

    1.9

    80

    2.2

    50

    4.0

    00

    4.0

    00

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    5. Theory and basic concepts

    Calculating Noise contributions from multiple sources

    Adding power values can be done in Watts (or mW) only

    Therefore, to calculate the summed amplitude of unequal noise contributors wemust convert dBm values in mW for each contributor

    P[mW] = 10(P[dBm]/10)

    Next add all of the values together in mW:

    PN-Tot [mW] = Ni[mW] Return this Total Noise value in dBm:

    =- o m - o m

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    5. Theory and basic concepts

    Desensitization

    ,

    signals

    Desensitization can be caused b man factors from s urious noise within the receiver to

    interfering signals

    To understand the effect that desensitization will have on our system we should know

    what our initial or benchmark sensitivity is

    Transceiver manufacturers generally state the sensitivity of their radio equipment

    Sensitivity specifications usually state the smallest signal amplitude that could be

    demodulated as received at the input of the receiver

    Any signal received from just below the sensitivity of the receiver to many times the

    amplitude of the initial sensitivity will affect the sensitivity of the receiver

    Usually in-band signals are the concern but strong out-of-band signals can reduce the

    receivers sensitivity as well

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    5. Theory and basic concept s

    Desensitization ()

    traffic within the coverage zone designed for the BTS

    If the Re eater is causin desensitization at the BTS then the re eater could have a better

    sensitivity than the BTS

    The amount of BTS desensitization that a Repeater will contribute can be minimized

    through design methodology

    There is a direct relationship between Repeater sensitivity and BTS sensitivity

    Repeaters, if engineered and configured properly, should not be major contributors to

    desensitization

    Repeaters, if not engineered and configured properly, can cause a great deal of BTS

    desensitization and shrink the effective coverage zone of the BTS considerably

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    5. Theory and basic concepts

    Desensitization()

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    5. Theory and basic concepts

    Base Station Sensitivity Before a Repeater

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    5. Theory and basic concepts

    An Engineered Repeater Site

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    5. Theory and basic concepts

    BTS Sensitivity is Degraded

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    5. Theory and basic concepts

    Repeater Sensitivity is Reduced

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    6. Deployment considerat ions

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    6. Deployment considerat ions

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    6. Deployment considerat ions

    Isolation

    For CDMA 15 dB Isolation Margin Recommended

    For AMPS 12 dB Isolation Margin Recommended

    Isolation Required = GDL + Isolation margin

    TechnologyRecommended

    Isolation margin

    CDMA 15 dB

    AMPS 12 dB

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    6. Deployment considerat ions

    How can antenna isolation be achieved?

    Use Narrow Beam Antennas

    Install Antennas 180 degrees apart

    Use the Antenna nulls to assist in maximizing Isolation.

    Polarization (donor and Repeater site) Main beam

    Always measure the Isolation / never assume isolation is adequate

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    6 D l t id t i

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    6. Deployment considerat ions

    Free Space Loss32.4 + 20 log (d [km]) + 20 log (f [MHz])

    90.0

    Free Space Loss32.4 + 20 log ( d [km]) + 20 log (f [MHz])

    130.0

    80.0

    85.0 125.0

    75.0

    L

    o

    ss

    (d

    B

    )

    115.0

    .

    o

    ss

    (d

    B

    )

    65.0

    .

    F

    ree

    S

    pa

    ce

    105.0

    110.0

    ree

    S

    p

    ac

    e

    L

    55.0

    60.0

    95.0

    100.0F

    50.0

    10 30 50 70 90 110

    130

    150

    170

    190

    Cellular

    90.0

    1 3 5 7 911 13 15 17 19

    Cellular

    Distance (m )PCS

    PCS

    6 D l t id t i

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    6. Deployment considerat ions

    Beginning of oscillation caused by

    lack of antenna isolation

    (signal integrity is altered)

    Proper Isolation is achieved

    (signal integrity is maintained)

    6 Deployment considerat ions

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    6. Deployment considerat ions

    Keep in mind

    Negative Link Gain is required between the Repeater and the BTS

    Always check the affect the Repeater Install has on the BTS

    Sensitivity can be transferred to the Repeater and that means from the BTS

    Calculate the actual Path Loss between the Repeater and the BTS

    Determine if you require an Attenuator

    Test Your Results

    6 Deployment considerat ions

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    6. Deployment considerat ions

    Typical C/I per technology

    6 Deployment considerat ions

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    6. Deployment considerat ions

    Propagation delay

    ,

    Those signals encounter delay traveling toward the mobile and through a Repeater there is

    additional dela due to the shar filterin characteristics of the Re eater

    Propagation delay through free space is approx. 4.1 chips per kilometer

    The propagation delay of the repeater is approximately 7 chips

    These additional delays must be accounted for in the Search Window settings

    Possible adjustments may be required for

    SRCH_WIN_A

    SRCH WIN N_ _SRCH_WIN_R

    6 Deployment considerat ions

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    6. Deployment considerat ions

    Propagation delay (formula)

    6 Deployment considerat ions

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    6. Deployment considerat ions

    Propagation delay (rules of thumb)

    delay including the delay through the Repeater (not too wide as that would slow down the

    mobile overall pilot searching speed)

    Set the Remaining list search window one or two steps above the Neighbor list search

    window setting

    Set the Active list search window according to measured results from your drive test

    1 chip = 0.814 s

    n -> . cps

    c = d / t c = 3 x 108 m/s

    = .= .

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    PCS repeaterempirical example

    PCS example

    Type Monopole Type Roof top

    Band PCS Band PCS

    # channel 1 # channel 1

    Distance 3.2 km Donor Ant. Gain 17.0 dBiSector Beta Donor Feeder Loss -2 dB

    PN 204

    RSSI -61 dBm

    Ec 31.26 dBm Ec/Io (PN = 44) -12 dB

    FRM output power

    Mobile readings at repeater site

    Design assumptions:1. Repeater should operate without coverage breathing; thus Dynamic Range will

    Full traffic 41.34 dBm Ec/Io (PN = 108) -11 dB

    Dynamic Range 10.08 dB Ec/Io (PN = 204) -8 dBEc/Io (PN = 320) -10 dB

    Selected donor Line of sight with PN 204an e a t on o tra c: = etween p ot on y to u tra c

    2. Area to cover is suffering from pilot pollution (6 PNs with Ec/Io ~ -13 dB,

    RSSI ~ -90dBm): We need to bring one dominant PN (Ec/Io > -6 dB, RSSI > -

    3. Our repeater donor antenna has a gain AD = +17 dBi and a feeder loss of FD= 2 dB.

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    PCS repeater example Path Loss calculations RSSI varies with traffic

    Pilot Power (Ec) is fixed at all times

    Lets base our calculation on constant power (i.e. Ec (PN 204))

    Ec (PN 204) = RSSI + Ec/Io (PN 204)

    = -61 + -8Ec (PN 204) = - 69 dBm = PM = Pilot 204 signal strength at the mobile

    (from the repeater location)

    The Path Loss between the donor site and the mobile is as follows:

    PLMB = PM - PB= -69 - 31.26100 3 dB 100 dB-100.3 dB ~ - 100 dB

    Now, lets try to obtain the Path Loss between the donor site and at the donor port of therepeater (going through the donor antenna system):

    PLDB = PD - PB= [PM + AD FD] - PB= [-69 + 17 2] - 31.26= -85.3 dB ~ -85 dB

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    PCS repeater example Downlink Gain Downlink Gain of the repeater should be set as follows:

    =GDL

    Rqd

    Ant. PC (PILOT)PC (FULL

    TRAFFIC)

    Repeater Output Power

    Down Link

    Thus:

    GDL = PC - PD - DR

    .

    90 dB 105 dB 36.0 dBm 46.0 dBm

    89 dB 104 dB 35.0 dBm 45.0 dBm

    88 dB 103 dB 34.0 dBm 44.0 dBm

    Repeater selection Based on our coverage objectives, lets assume a

    Standard Power repeater (AR-3400) is adequate.Therefore:

    87 dB 102 dB 33.0 dBm 43.0 dBm

    86 dB 101 dB 32.0 dBm 42.0 dBm

    85 dB 100 dB 31.0 dBm 41.0 dBm

    84 dB 99 dB 30.0 dBm 40.0 dBm

    83 dB 98 dB 29.0 dBm 39.0 dBm

    DL =

    PC = Repeater Average Output Power for the numberof carriers you design your system with (+33dBm for 1 channel, +28 dBm / channel for 2channels with and AR-3400)

    82 dB 97 dB 28.0 dBm 38.0 dBm

    81 dB 96 dB 27.0 dBm 37.0 dBm80 dB 95 dB 26.0 dBm 36.0 dBm

    79 dB 94 dB 25.0 dBm 35.0 dBm

    78 dB 93 dB 24.0 dBm 34.0 dBm

    77 dB 92 dB 23.0 dBm 33.0 dBm

    PC (PILOT) = +23 dBm

    As traffic increases on the system, Pc (FULL TRAFFIC) willreach +33 dBm = Maximum output power of therepeater.

    76 dB 91 dB 22.0 dBm 32.0 dBm

    75 dB 90 dB 21.0 dBm 31.0 dBm

    74 dB 89 dB 20.0 dBm 30.0 dBm

    73 dB 88 dB 19.0 dBm 29.0 dBm

    72 dB 87 dB 18.0 dBm 28.0 dBm

    71 dB 86 dB 17.0 dBm 27.0 dBm

    70 dB 85 dB 16.0 dBm 26.0 dBm

    Next step Now we need to set the GUL and ensure our repeater does

    not desensitize the BTS

    69 dB 84 dB 15.0 dBm 25.0 dBm

    68 dB 83 dB 14.0 dBm 24.0 dBm

    67 dB 82 dB 13.0 dBm 23.0 dBm

    66 dB 81 dB 12.0 dBm 22.0 dBm

    65 dB 80 dB 11.0 dBm 21.0 dBm

    64 dB 79 dB 10.0 dBm 20.0 dBm

    63 dB 78 dB 9.0 dBm 19.0 dBm

    62 dB 77 dB 8.0 dBm 18.0 dBm

    61 dB 76 dB 7.0 dBm 17.0 dBm

    60 dB 75 dB 6.0 dBm 16.0 dBm

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    PCS repeater example Uplink Gain Uplink Gain of the repeater should be set to

    minimize Noise Contribution from the GUL dBm mW mW dBmBTS

    Desens.

    NIN(from repeater) N (total)

    p n

    NIN (rep) = NTH + NF + GUL PLDB

    90 dB -103.4 4.6E-11 5.1E-11 -102.9 -10.2 dB

    89 dB -104.4 3.7E-11 4.2E-11 -103.8 -9.3 dB

    88 dB -105.4 2.9E-11 3.4E-11 -104.7 -8.4 dB

    Thus:GUL = NIN (rep) - NTH - NF + PLDB

    87 dB -106.4 2.3E-11 2.8E-11 -105.5 -7.6 dB

    86 dB -107.4 1.8E-11 2.3E-11 -106.3 -6.8 dB

    85 dB -108.4 1.5E-11 1.9E-11 -107.1 -6.0 dB

    84 dB -109.4 1.2E-11 1.6E-11 -107.8 -5.3 dB

    83 dB -110.4 9.2E-12 1.4E-11 -108.5 -4.6 dB.

    Noise contribution from the repeater must bekept to a minimum to optimize BTS sensitivity.The art of controlling injected noise from arepeater is tied into the success of your

    82 dB -111.4 7.3E-12 1.2E-11 -109.1 -4.0 dB

    81 dB -112.4 5.8E-12 1.1E-11 -109.7 -3.4 dB80 dB -113.4 4.6E-12 9.5E-12 -110.2 -2.9 dB

    79 dB -114.4 3.7E-12 8.6E-12 -110.7 -2.4 dB

    78 dB -115.4 2.9E-12 7.8E-12 -111.1 -2.0 dB

    77 dB -116.4 2.3E-12 7.2E-12 -111.4 -1.7 dB

    repeater deployment.

    Total Noise at the BTS is obtained as follows:

    N = N + N (adding power is in W)

    76 dB -117.4 1.8E-12 6.7E-12 -111.7 -1.4 dB

    75 dB -118.4 1.5E-12 6.4E-12 -112.0 -1.1 dB

    74 dB -119.4 1.2E-12 6.1E-12 -112.2 -0.9 dB

    73 dB -120.4 9.2E-13 5.8E-12 -112.4 -0.7 dB

    72 dB -121.4 7.3E-13 5.6E-12 -112.5 -0.6 dB

    71 dB -122.4 5.8E-13 5.5E-12 -112.6 -0.5 dB

    70 dB -123.4 4.6E-13 5.4E-12 -112.7 -0.4 dB

    BTS desensitization is:Desensitization = NTOT - NTH (dB)

    69 dB -124.4 3.7E-13 5.3E-12 -112.8 -0.3 dB

    68 dB -125.4 2.9E-13 5.2E-12 -112.9 -0.3 dB

    67 dB -126.4 2.3E-13 5.1E-12 -112.9 -0.2 dB

    66 dB -127.4 1.8E-13 5.1E-12 -112.9 -0.2 dB

    65 dB -128.4 1.5E-13 5.0E-12 -113.0 -0.1 dB

    64 dB -129.4 1.2E-13 5.0E-12 -113.0 -0.1 dB

    63 dB -130.4 9.2E-14 5.0E-12 -113.0 -0.1 dB

    62 dB -131.4 7.3E-14 5.0E-12 -113.0 -0.1 dB

    61 dB -132.4 5.8E-14 5.0E-12 -113.0 -0.1 dB

    60 dB -133.4 4.6E-14 4.9E-12 -113.1 0.0 dB

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    PCS repeater example Uplink Gain Typically, we should aim for: GUL dBm mW mW dBm

    BTS

    Desens.

    NIN(from repeater) N (total)

    p n

    Desensitization < 1 B w ic correspon s to:NIN (rep) < -119 dBm

    In this example, the noise contribution of the

    90 dB -103.4 4.6E-11 5.1E-11 -102.9 -10.2 dB

    89 dB -104.4 3.7E-11 4.2E-11 -103.8 -9.3 dB

    88 dB -105.4 2.9E-11 3.4E-11 -104.7 -8.4 dB

    repeater will affect the sensitivity of the basestation by 1 dB. Thus reducing the Reverse Linkcoverage by 1 dB

    87 dB -106.4 2.3E-11 2.8E-11 -105.5 -7.6 dB

    86 dB -107.4 1.8E-11 2.3E-11 -106.3 -6.8 dB

    85 dB -108.4 1.5E-11 1.9E-11 -107.1 -6.0 dB

    84 dB -109.4 1.2E-11 1.6E-11 -107.8 -5.3 dB

    83 dB -110.4 9.2E-12 1.4E-11 -108.5 -4.6 dB

    n ur an env ronments, t e ase tat on stypically Down-Link limited

    In rural environments, the Base Station is

    82 dB -111.4 7.3E-12 1.2E-11 -109.1 -4.0 dB

    81 dB -112.4 5.8E-12 1.1E-11 -109.7 -3.4 dB80 dB -113.4 4.6E-12 9.5E-12 -110.2 -2.9 dB

    79 dB -114.4 3.7E-12 8.6E-12 -110.7 -2.4 dB

    78 dB -115.4 2.9E-12 7.8E-12 -111.1 -2.0 dB

    77 dB -116.4 2.3E-12 7.2E-12 -111.4 -1.7 dB-

    Desensitization will be observed to a greaterscale

    76 dB -117.4 1.8E-12 6.7E-12 -111.7 -1.4 dB

    75 dB -118.4 1.5E-12 6.4E-12 -112.0 -1.1 dB

    74 dB -119.4 1.2E-12 6.1E-12 -112.2 -0.9 dB

    73 dB -120.4 9.2E-13 5.8E-12 -112.4 -0.7 dB

    72 dB -121.4 7.3E-13 5.6E-12 -112.5 -0.6 dB

    71 dB -122.4 5.8E-13 5.5E-12 -112.6 -0.5 dB

    70 dB -123.4 4.6E-13 5.4E-12 -112.7 -0.4 dB

    It is the role of any repeater system designer toevaluate how much noise can the Base Stationtolerate from the repeater without adverselyaffecting its sensitivity

    69 dB -124.4 3.7E-13 5.3E-12 -112.8 -0.3 dB

    68 dB -125.4 2.9E-13 5.2E-12 -112.9 -0.3 dB

    67 dB -126.4 2.3E-13 5.1E-12 -112.9 -0.2 dB

    66 dB -127.4 1.8E-13 5.1E-12 -112.9 -0.2 dB

    65 dB -128.4 1.5E-13 5.0E-12 -113.0 -0.1 dB

    64 dB -129.4 1.2E-13 5.0E-12 -113.0 -0.1 dB

    63 dB -130.4 9.2E-14 5.0E-12 -113.0 -0.1 dB

    62 dB -131.4 7.3E-14 5.0E-12 -113.0 -0.1 dB

    61 dB -132.4 5.8E-14 5.0E-12 -113.0 -0.1 dB

    60 dB -133.4 4.6E-14 4.9E-12 -113.1 0.0 dB

    8. Repeater Conf igurat ion

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    8. Repeater Conf igurat ion

    a repeater

    provides the basis for the settings that we will applyto the repeater

    There are a number of tools available in therepeater to assist us in the configuration process

    Remember to test your results after configuring a

    re eater to ensure that our new covera e area aswell as the existing macro area are optimized toprovide the best possible result

    8. Repeater Conf igurat ion

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    8. Repeater Conf igurat ion

    Repeater Variants

    Gain

    A

    8. Repeater Conf igurat ion

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    p g

    Channel Selective Repeaters

    Channel Selective repeaters are configured on a per

    channel basis for uplink and downlink gain

    Channel selective repeaters automatically tune to thechannel frequency and bandwidth

    Channel selective repeaters offer RSSI based on theenergy seen at the input of the repeater relevant to that

    Channel selective repeaters have a wider gain setting

    8. Repeater Conf igurat ion

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    p g

    Band Selective Repeaters

    Band Selective repeaters have a settable bandwidthinstead of a channel number input and as manychannels as you have can pass through it

    Band Selective repeaters dont offer an RSSI becausethere could be many signals input into the repeater

    Band selective repeaters have a lower gain settablerange for the lowest achievable noise figure

    en ocate near a , a an se ect ve repeaterrequires some extra consideration in the uplink

    the same successful results as a Channel Selectiveinstallation

    8. Repeater Conf igurat ion

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    p g

    Calculate the actual path loss between the BTS site and the repeater site.

    To do this simply, you must know the power level being transmitted from the BTS.the donor antenna connector where it attaches to the repeater. Please refer to thediagram. Take the power level transmitted from the BTS and subtract the powerreceived at the Repeater site through the donor antenna and you have the actual path

    . .always vary.

    Example: Pilot power from BTS radio is +31.26 dBm. c o

    = -8 dB

    Equation: Path Loss = BTS TX Power (Pilot power only)- R I (at the Repeater donor antenna) + Ec/Io (donor sector)

    For this example: Path Loss = +31.26 [ -55 -8 ] = 94.26 dB

    8. Repeater Conf igurat ion

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    [Step 2] Set your Uplink gain according to your path loss.

    ou mus ave a nega ve n ga n e ween erepeater and the BTS to enable the noise powerof the repeater to arrive at the BTS somewherearoun t e sensitivity o t e BTS wit out t erepeater. The rule of thumb here is to have a 10dB ne ative link ain. Take the actual ath lossas calculated in step one and subtract 10 dB toestablish your uplink gain setting. In the

    would be 84 dB.

    8. Repeater Conf igurat ion

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    power from the repeater site at the base stationreceiver or call your Network and ask for the MTX

    off and then with the repeater on. The noise valuesshould remain the same or have very little variance.

    contribution in noise power received from therepeater attenuate the uplink of the repeater

    attenuation to the uplink path.

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    .

    [email protected]

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