CDMA Link Budget

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CDMA RF Planning Unit 5


Main Content

Basic conception of the link budget

IS-95 reverse link budget

Cdma2000-1X reverse link budget


Link Budget - What’s it for?

1. Establish Reverse Link Maximum Allowable Pathloss

2. Sets Forward Channel Powers to match Reverse LinkCoverage (based on fowards Pilot Channel)


Link Budget - What’s it for?

2 - DOWNLINKUse Max Uplink Pathloss to calculate Downlink BS TX Powers

1 - UPLINKCalculate Max Uplink Pathloss

MobilePilot RX

MobilePaging RX

MobileSync RX

MobileTraffic RX

M/STX

BODYLOSS

BASEPilot TX

BASEPaging TX

BASESync TX

BASETraffic TX

BASETraffic RX

INSERTION&

CABLELOSS

BASEANTGAIN

SHOGAIN

PATHLOSS

FADEMARGIN

DIV.GAIN

LoadingFactor


Link Budget - What’s it for?Mobile

Pilot RX

MobilePaging RX

MobileSync RX

MobileTraffic RX

M/STX

BODYLOSS

BASEPilot TX

BASEPaging TX

BASESync TX

BASETraffic TX

BASETraffic RX

INSERTION&

CABLELOSS

BASEANTGAIN

SHOGAIN

PATHLOSS

FADEMARGIN

2 - DOWNLINKUse Max Uplink Pathloss to calculate Downlink BS TX Powers

1 - UPLINKCalculate Max Uplink Pathloss

DIV.GAIN

LoadingFactor

Maximum Uplink Pathloss

Maximum Uplink Pathloss(applied to Downlink)


Composition of the Wireless Link

Receiver

antenna

antenna

Transmission Line

Transmitter

Transmission Line

Power output

Loss of transmission lineGain

Path loss

Gain

Loss of transmission lineSensitivity

Margin


Link Budget Model

Mobile BTSCable loss

Antenna gain

Path loss

Antenna gain

Cable loss Margin

downlink

uplink

Link budgetDetermine allowable maximum path lossDetermine maximum cell radius

Downlink and uplinkKeep balance

Link budgetDetermine allowable maximum path lossDetermine maximum cell radius

Downlink and uplinkKeep balance

building

Margin：slow fade + penetrationloss+...


Transmitter Side

)()()(

)()(

dBLossorBodyCabledBiinrAntennaGaTransmitte

dBmrPowerTransmittedBmrEIRPTransmitte

−+

=


Receiver Side

)()()/(

)/()(Re

HzdBDataRatedBreqNoEb

HzdBmceNoiseInterferendBmitivityceiverSens

−++

=


Penetration Loss

Main mechanism：

diffraction, refractionCalculationmethod：Statistics.

Building PenetrationCar Penetration

?

?

?

Representative value of building penetration loss

Dense Urban

Urban

Suburban

Rural

25 dB

20 dB

15 dB

6 dB

Open 0 dB


Fading margin

90%

75%

Assuming at least 75% area at the edge of the cell（90% within the cell）can reliably receive signal stronger than -105dBm. Normal deviation is taken as 8dB. From the chart, the probability at 0.675 is 75%.

0.675 x 8 = 5.4 dB-105 + 5.4 = -99.6 dBm

The mean signal intensity m is designed as -99.6 dBm

Deviation from m

Cumulate normal probability distribution

0%10%20%30%40%50%60%70%80%90%

100%

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

75%

0.675σ

area

-99.6dBm

σ=8dB

RSSI

Normal distribution

0.675σ=5.4 dΒ

- 105 dBm

[ ]dxxxPP mx

xx 2

2

0

0 2)(

21

0 exp][σπσ−−

∞

∫=≥=


BTSRX

Pathloss

50% Cell EdgeStreet-LevelNo Load

Fade marginLoad factor


BTSRX

Pathloss


75% Cell EdgeIn-BuildingBody LossSoft Handoff GainNo LoadFade margin

Load factor



75% Cell EdgeIn-BuildingBody LossSoft Handoff GainNo Load

BTSRX

Pathloss

75% Cell EdgeIn-BuildingBody LossSoft Handoff GainWith LOAD

Final Cell RadiusMore near!

Fade margin

Load factor


Soft handoff gain

• Soft handoff gain is the available margin for Uplink and Downlink in poor coverage areas (that is, soft hand-off region) due to combination of two or more relatively uncorrelated signals.

• The result is that we can maintain the required QoS for a lower signal threshold - the link can sustain a greater path loss.

• The soft handoff gain is dependent on the shadowing standard deviation and coverage reliability.


-120

-115

-110

-105

-100

-95

-90

-85

-80

-75

-70

x

1 Normally distributed Signal from 1 Base station - x


-120

-115

-110

-105

-100

-95

-90

-85

-80

-75

-70

xy

2 Separate Normally distributed Signals from 2 Base stations


Combined Signal showing Soft Handoff Gain = aprox +4dB

-120

-115

-110

-105

-100

-95

-90

-85

-80

-75

-70


Combined Signal showing Soft Handoff Gain = aprox +4dB-70

-120

-115

-110

-105

-100

-95

-90

-85

-80

-75


Path Loss

TotalGaindBdBdBmceiverSidedBmrSideTransmitte

+−−−=

)(Margin Fading)( Lossn Penetratio)(Re)(Loss(dB)Path Allowable

Propagation Model：

PL(dB)=Function(F, HA, HM, D, C)

PL：Path Loss (dB)F： Frequency (MHz) D： Distance (km)H： BTS (MS) antenna effective height (m)C： Terrain Correction: dense urban, urban,

suburban, rural


Hata Model, COST-231 Model Input

FrequencyDistanceAntenna effective heightTerrain (urban, suburban, rural, etc.)

RSSI, dBm

-120

-110

-100

-90

-80

-70

-60

-50

0 3 6 9 12 15 18 21 24 27 30 33

Distance from Cell Site, km

FieldStrength,dBuV/m

+90

+80

+70

+60

+50

+40

+30

+20

Blue line shows the result of drive testGray line shows

the predication result of Hatamodel

Hata ModelPL (dB) = 69.55 + 26.16 log (F) - 13.82 log(H) + (44. 9 - 6.55 log(H) )*log (D) + C

Hata ModelPL (dB) = 69.55 + 26.16 log (F) - 13.82 log(H) + (44. 9 - 6.55 log(H) )*log (D) + C

Hata ModelPL： Path Loss (dB)F： Frequency (150Hz - 1500 MHz)D： Distance (km)H： BTS antenna effective height (m)C:Terrain correction：dense urban0 dB

urban：- 5 dBsuburban：- 10 dB

rural：- 17 dB

Hata ModelPL： Path Loss (dB)F： Frequency (150Hz - 1500 MHz)D： Distance (km)H： BTS antenna effective height (m)C:Terrain correction：dense urban0 dB

urban：- 5 dBsuburban：- 10 dB

rural：- 17 dB

COST-231PL (dB) = 46.3 + 33.9*logF - 13.82*logH + (44.9 - 6.55*logH)*log D + C

COST-231PL (dB) = 46.3 + 33.9*logF - 13.82*logH + (44.9 - 6.55*logH)*log D + C

COST-231PL： Path Loss (dB)F： Frequency (1500 - 2000 MHz)D： Distance (km)H： BTS antenna effective height (m)C： Terrain correction：dense urban -2 dB

Urban: -5 dBSuburban: -8 dBRural: -10 dBOpen: -26 dB

COST-231PL： Path Loss (dB)F： Frequency (1500 - 2000 MHz)D： Distance (km)H： BTS antenna effective height (m)C： Terrain correction：dense urban -2 dB

Urban: -5 dBSuburban: -8 dBRural: -10 dBOpen: -26 dB


Main Content





Propagation EnvironDense Urban Urban Suburban Rural Open Remark

MS rating Tx Power(dBm) 23 23 23 23 23

MS Antenna Gain(dBi) 0 0 0 0 0

Body Loss（dB） 3 3 3 3 3

MS ERP（dBm) 20 20 20 20 20

BS Antenna Gain(dBi) 15.70 15.70 15.70 11 11

BS jumper loss(dB) 1 1 1 1 1 cluding the connector

BS feeder loss(dB/100m 6 6 6 6 6

BS feeder length(m) 50 50 50 50 50

other loss estimate(dB) 1 1 1 1 1 as duplexer and arrester

BS antenna feeder loss(dB) 5 5 5 5 5

Thermal Noise Density(dBm -174 -174 -174 -174 -174

Noise Figure（dB） 5 5 5 5 5

Bit Rate（kbps） 9600 9600 9600 9600 9600

Eb/No 6.80 6.80 6.80 6.80 6.80 idering diversity gain

Loading 0.50 0.50 0.50 0.50 0.50

Interference Margin（dB） 3.01 3.01 3.01 3.01 3.01

BS Sensitivity(dBm) -119.37 -119.37 -119.37 -119.37 -119.37

Handoff Gain（dB） 4 4 4 4 4 f not soft handoff,it's zero.Fading Deviation(dB) 8 8 8 8 8

Edge Coverage Probability 0.75 0.75 0.75 0.75 0.75

Fading Margin(dB) 5.40 5.40 5.40 5.40 5.40

Max Allowable Path Loss(dB 148.67 148.67 148.67 143.97 143.97

Building Penetration Loss (d 25 20 12 10 6 lues come from field test

Up Link Path Loss(dB) 123.67 128.67 136.67 133.97 137.97BS Antenna Height(m) 30 40 50 50 50

MS Antenna Height(m) 1.50 1.50 1.50 1.50 1.50

RF Central Frequency(MHz) 825 825 825 825 825

Hata model Terrain Correctio 0 0 -9.72 -18.91 -28.18 Hata model1km Path Loss A（dB） 125.43 123.69 112.63 103.44 94.17 L=A+BlogRSlope B 35.22 34.41 33.77 33.77 33.77

BS Radius R(km) 0.89 1.40 5.15 8.02 19.81

IS-95-A system 800M reverse link budget


Link Budget Notes （1）

Body loss

A body loss of 3dB is

often used in link budget.



Antenna gain

450M

In the dense urban area, for directional antenna, horizontal BW: 65°, vertical BW: 7°～10° , gain :15.5dBi

In the urban and suburban area, for directional antenna, horizontal BW: 90°, vertical BW: 7°～10° , gain :14dBi.

In the rural area, omni-directional antenna is used, gain :11dBi. There is different gain for different antennas selected.

In case of keeping up other conditions, the antenna’s high gain is useful to increase the coverage radius.



Antenna gain

800M

In the dense urban area, for directional antenna, horizontal BW: 65°, vertical BW: 7°～10° , gain :17 dBi

In the urban and suburban area, for directional antenna, horizontal BW: 90°, vertical BW: 7°～10° , gain :15.7 dBi.

In the rural area, omni-directional antenna is used, gain :11dBi. There is different gain for different antennas selected.




Antenna gain

1.9G

In the dense urban area, for directional antenna, horizontal BW: 65°, vertical BW: 7°～10° , gain :18dBi

In the urban and suburban area, for directional antenna, horizontal BW: 90°, vertical BW: 7°～10° , gain :16dBi.

In the rural area, omni-directional antenna is used, gain :~11dBi. There is different gain for different antennas selected.




BTS antenna feeder loss

450M

There are two cases to discuss for the feeder from BTS to antenna:

If the feeder is shorter than 15m，normally only ½ inch long jumper is used. Therefore, in the budget list, the jumper loss is 1dB，the connector loss is 1dB, the total loss is 2dB.

If there is not only ½ inch jumper but also longer 7/8 inch feeder, the loss of 7/8 inch feeder should be considered as，

feeder loss=the length of 7/8 inch feeder*4(dB)/100m




800MThere are two cases to discuss for the feeder from BTS to

antenna:

If the feeder is shorter than 15m，normally only ½ inch long jumper is used. Therefore, in the budget list, the jumper loss is 1dB，the connector loss is 1dB, the total loss is 2dB.

If there is not only ½ inch jumper but also longer 7/8 inch feeder, the loss of 7/8 inch feeder should be considered as，





1.9GThere are two cases to discuss for the feeder from

BTS to antenna:

If the feeder is shorter than 15m，normally only ½ inch jumper is used. Therefore, in the budget list, the jumper loss is 1dB，the connector loss is 1dB, the total loss is 2dB.

If there is not only ½ inch jumper but also 7/8 inch feeder, the loss of 7/8 inch feeder should be considered as，




Building Penetration Loss

Here is experience value. For dense urban, urban,

suburban, and rural area, the loss is respectively

25dB, 20dB, 15dB, 6dB. Actual penetration can be

adjusted by real surrounding building.

Interference margin

LoadingRxPower

−=

11



Antenna HeightNormally, in the dense area with concentratedcapacity distribution, the antenna’s height is relatively low, in order to reduce the pilot pollution and interference to other area.

In the open area with sparse capacity distribution, the antenna height is relatively high, in order to cover more area.

For dense urban, urban, suburban and rural area, the antenna height is respectively 30m, 40m, 50m, 50m.


Main Content





Propagation Environme

Traffic Type

Bit Rate（kbps） 153.60 76.80 38.40 19.20 9.60 1X IS-95-A MS rating Tx Power(dBm) 23 23 23 23 23 23 23

MS Antenna Gain(dBi) 0 0 0 0 0 0 0

Body Loss（dB） 3 3 3 3 3 3 3

MS ERP（dBm) 20 20 20 20 20 20 20

BS Antenna Gain(dBi) 15.70 15.70 15.70 15.70 15.70 15.70 15.70

BS jumper loss(dB) 1 1 1 1 1 1 1

BS feeder loss(dB/100 6 6 6 6 6 6 6

BS feeder length(m) 50 50 50 50 50 50 50

other loss estimate(dB) 1 1 1 1 1 1 1

BS antenna feeder loss(dB) 5 5 5 5 5 5 5

Thermal Noise Density(dBm -174 -174 -174 -174 -174 -174 -174

Noise Figure（dB） 5 5 5 5 5 5 5

Bit Rate（kbps） 153600 76800 38400 19200 9600 9600 9600

Eb/No 2.20 2.70 3.30 4.00 4.90 4.90 6.80

Loading 0.50 0.50 0.50 0.50 0.50 0.50 0.50

Interference Margin（dB） 3.01 3.01 3.01 3.01 3.01 3.01 3.01

BS Sensitivity(dBm) -111.93 -114.44 -116.85 -119.16 -121.27 -121.27 -119.37

Handoff Gain（dB） 4 4 4 4 4 4 4

Fading Deviation(dB) 8 8 8 8 8 8 8

Edge Coverage Probability 0.75 0.75 0.75 0.75 0.75 0.75 0.75

Fading Margin(dB) 5.40 5.40 5.40 5.40 5.40 5.40 5.40

Max Allowable Path Loss(d 141.23 143.74 146.15 148.46 150.57 150.57 148.67

Building Penetration Loss ( 20 20 20 20 20 20 20

Up Link Path Loss(dB) 121.23 123.74 126.15 128.46 130.57 130.57 128.67BS Antenna Height(m) 40 40 40 40 40 40 40

MS Antenna Height(m) 1.50 1.50 1.50 1.50 1.50 1.50 1.50

RF Central Frequency(MHz 825 825 825 825 825 825 825

Hata model Terrain Correct 0 0 0 0 0 0 01km Path Loss A（dB） 123.69 123.69 123.69 123.69 123.69 123.69 123.69

Slope B 34.41 34.41 34.41 34.41 34.41 34.41 34.41

BS Radius R(km) 0.85 1.00 1.18 1.38 1.58 1.58 1.40

Urban

data voice

cdma2000 1x system 800M reverse link budget



Loading

In this budget, the loading is taken to

be 50%.

The loading value for 1X can be

taken to be 75％ by the reality.



Coverage RadiusIn the same environment，the higher the transmission data rate, the smaller coverage radius can be supported by 1x system.Compared with voice service，coverage radius of high-speed data service is smaller. But in general, especially in urban area, it is capacity that limits the cell radius, so the real radius is smaller than that of link budget for existing IS95-A BS ，thus the data coverage radius supported by 1X can reach real BS coverage radius.


Documents

CDMA Link Budget