Radio Link Budget - W

Radi Radio o Lin Link k Budg Budget et - Upli Uplink nk MDC Gain SHO Gain against Slow fading SHO Gain against fast fading

AntennaGain NodeB Antenna Gain

Slow fading margin Slow fading margin Fast fading margin Interference margin Body Loss Cable Loss

UE

UE

P   a t   h L  o s  s 

Antenna Gain

Transmit Power 

UPLINK

CableLoss NodeB Sensitivity

Penetration Loss

BUDGET Antenna Gain

Maximum allowable path loss

SHO Gain

Penetration Loss

Margin Loss

NodeB reception sensitvity

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NodeB

ntenna Ga Gaiin

Slow f adi ading ma mar  r gin Slow f adi ading ma mar  r gin Fastt f adi Fas ading ma mar  r gin Interf er ence ence ma mar  r gin Body Loss Cablle Loss Cab

UE

P  a  t  

NodeB

ntenna Ga Gaiin

r ansmit ansmit Powe Power  r 

Penetr  Pene tr ati tion on Loss

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 Algorithm Introduction

Uplink (reverse)

 PL_UL=Pout_UE + Ga_BS + Ga_UE ± Lf_BS + Ga_SHO ± Mpc± Mf  ± MI ± M_BN ± Lp ± Lb ± S_BS  PL_UL: Maximum propagation loss of the Uplink  Pout_UE: Maximum transmit power of the traffic channel of the UE  Lf_BS: Cable loss  Ga_BS: Antenna gain of the BS; Ga_UE: Antenna gain of the MS  Ga_SHO: Gain of soft handover   Mpc: Margin for fast power control  Mf: Slow fading margin (related to the propagation environment)  MI: Interference margin (related to the designed system capacity)  M_BN: Margin for Background Noise (related to the electroma netic environment

Elements of WCDM A Uplink Budget Max Power of TCH 2. Body Loss 3. Gain of UE Tx  Antenna 4. EIRP 5. Gain of BS Rx  Antenna 6. Cable Loss 7. Noise Figure (BS) 8. Required Eb/No (BS) 9. Sensitivity of BS 1.

12.Background

Noise

Level 13.Margin for  Background Noise 14.Fast Fading Margin 15.SHO Gain over Fast Fading 16.Minimum Signal Strength Required 17.Penetration Loss 18.Std. dev. of Slow

Elements of WCDM A Uplink Budget

 1. Max Power of TCH (dBm)

 ± For a UE, the maximum power of each traffic channel is usually the nominal total transmit power. There are many types of UE in a commercial network, so this parameters should be reasonably set in the link budget according to the specifications of a mainstream commercial cell TS 25.101 v3.7.0 Grade ofand UE power  2001-06 phone the requirement of the operator  6.2.1

Power Class

Nominal maximum output power 

Tolerance

1

+33dBm

+1/-3dB

2

+27dBm

+1/-3dB

3

+24dBm

+1/-3dB

4

+21dBm

+2/-2dB



Elements of WCDM A Uplink Budget 2. Body Loss (dB)  ± For voice service, the body loss is 3 dB.  ± Because the data service mainly involves reading and video, the UE is relatively not so close to the body, so the body loss is 0 dB

 3. Gain of UE Tx Antenna (dBi)  ± Generally, assume that the receiver and transmitter  gain of the UE antenna are both 0 dBi

 4. EIRP (dBm)  ± UE EIRP (dBm) = UE Tx Power (dBm) - Body Loss (dB) + Gain of UE Tx Antenna (dBi)

Elements of WCDM A Uplink Budget

 5. Gain of BS Rx Kathrein 741794  Antenna (dBi) 1710~2170MHz Frequency range

Kathrein 741790

(dual band for  DCS and UMTS)

Frequency

Polarization

+45O, -45O

range

Gain

18.5dBi

Polarization

Vertical

HPBW (1920~2170MHz)

Horizontal: 63O Vertical:6.5O

Gain

11dBi

HPBW

Vertical: 7O

Electrical tilt

Fixed, 0O

Electrical tilt

O

Fixed, 2

1920~2170MHz

Elements of WCDMA Uplink Budget

 6. Cable Loss (dB)

Bracket

 ± Including the loss of the feeders and all of  the connectors.

Tilt adjuster 

ntenna

 Lower jumper   Connector (between jumper , feeder , cabinet, and lightning arrester )

Bracket Upper jumper 

 Feeder  Feeder 

 Upper jumper 

 ± Loss of the feeder :

Lightning arrester  Feeder fixing clip

Feeder window

Lower jumper 

 7/8-inch feeder : 6.1 dB / 100m for 2GHz

Feeder grounding clip

 5/4-inch feeder : 4.5 dB / 100m for 2GHz

 ± Other connecter loss is assumed 0.8 dB. Feeder installation

Elements of WCDM A Uplink Budget

 7. Noise Figure (dB)

 ± Noise figure (NF): It is used to measure the noise performance of an amplifier. It refers to the ratio of  the input SNR to the output SNR of the antenna NF

= SNR i / SNR o = (Si / Ni) / (So / No)

 ± Thermal noise of receiver (per Hertz):  PN = K×T×BW×NF = -174 (dBm/Hz) + 10lg(3.84MHz / 1Hz) + NF(dB) = -108 (dBm/3.84MHz) + NF (dB)



Elements of WCDM A Uplink Budget 8. Eb/No Required (dB)  ± It is obtained through link simulation. It is related to the following:  Configuration of receiver diversity  Multi-path environment  Bearer type (service)

 9. Sensitivity of BS Receiver (dBm)  ± Sensitivity of Receiver (dBm) = PN(dB) + required Eb/No (dB) 10lg[3.84Mcps/Rb(kbps)] = -174 (dBm/Hz) + NF (dB) + 10lg[1000 * Rb (kbps)] + Eb/No (dB)

Elements of WCDM A Uplink Budget  10. Uplink Cell Load  N 

L UL

 N 

! 1  i   §  L  j ! 1  i   §

 EbvsNo   R  j

 j

v  j

W  1 1  ± Uplink cell load is used to measure the uplink load of  a cell  ± The higher the uplink cell load, the higher the uplink interference  ± If the uplink load is about 100% , the uplink interference becomes infinite, and the corresponding capacity is the maximum capacity



Elements of WCDM A Uplink Budget 11. Uplink Interference Margin (dB)  N o ise

ise

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 I TOT   P  N 

1

!

!

 N 

1

§

 L j

1

50% Load ² 3dB 60% Load ² 4dB 75% Load ² 6dB

1 1  LUL

Elements of WCDM A Uplink Budget  12. Background Noise Level (dBm)  ± External electromagnetic interference sources:  Wireless transmitters (GSM, microwave, radar, television station, and so)   Automobile ignition  Lightning  «

 ± For the planning for a specific area, it is recommended to estimate the local interference through noise test

Elements of WCDM A Uplink Budget  13. Margin for Background Noise Level (dB)  ± Suppose the thermal noise of the receiver is X dBm, the background interference level is Y dBm, then received signal should be larger  than before to overcome the noise, so the margin for the background noise should be: Margin for Background Noise = 10log (10X/10 + 10Y/10) dBm - X dBm

Elements of WCDM A Uplink Budget  14. Fast Fading Margin (dB)  ± In the link budget, the demodulation performance of  the used receiver is the simulation result based on the assumed ideal power control. In an actual system, because of the limited transmit power of the transmitter, non-ideal factors are introduced in the closed loop power control  ± Effect of power control margin on the uplink demodulation performance:  The simulation shows the following: When the HeadRoom is large, the target Eb/No set in the outer loop power control is appropriate to the simulation result under the ideal power  control. As the power margin decreases, the Eb/No gradually increases (if the power margin decreases by 1 dB, the required Eb/No increases by about 1 dB). If power control performance is almost not available, the BER/BLER cannot be

Elements of WCDM A Uplink Budget

 15. SHO Gain over Fast Fading (dB)

 ± The soft handover gain includes two parts:  Multiple unrelated soft handover branches lower  the required margin for fading, which results in multi-cell gain  Gain for the link demodulation of the soft handover   ±macro diversity combining gain

 ± The SHO Gain over Fast Fading refer to the Macro Diversity Combination gain and reducing the request for fast fading margin  ± This value is obtained through simulation. The typical value is 1.5 dB.

Elements of WCDM A Uplink Budget  16. Minimum Signal Strength Required (dBm)  ± The required minimum signal level should be: Sensitivity of the Receiver + all the loss and margins  ± all the gain  ± Minimum Signal Strength Required = Sensitivity of Receiver (dBm) + Body Loss (dB) + Interference Margin (dB) + Margin for Background Noise (dB) + Fast Fading Margin (dB) - Gain of  Antenna (dBi) - SHO Gain over fast fading (dB)

Elements of WCDM A Uplink Budget

 17. Penetration Loss (dB)

 ± Indoor penetration loss refers to the signal level difference between the average strength near the wall outside the building and that of inside the building  ± The penetration loss is related to building type, arrive angle of the radio wave, and so on. In link budget, assume that the penetration loss is subject to the lognormal distribution.  ± It is uneconomical to provide good indoor coverage through an outdoor BS. Inside the building it should be covered using special indoor coverage solution  ± In the actual construction of a commercial network, the enetration loss mar in is usuall s ecified b

Elements of WCDM A Uplink Budget  18. Std. dev. of Slow Fading (dB) ± Std. dev. of indoor path loss  ± Suppose the standard deviation of the path loss outdoor is X dB, that of the Penetration Loss is Y dB, the standard deviation of path loss indoor can be get by sqrt( X2 + Y2 )

Elements of WCDM A Uplink Budget  19. Edge coverage Probability  ± If the transmit power of a UE hits the maximum threshold, but still cannot overcome the path loss to guaranty the lowest receive level, the radio link will drop or the UE will fail to access  ± If the designed signal level at the edge of the cell equals to the Minimum Signal Strength Required, the actual measurement result will obey the normal distribution.  This means there is a 50% probability that the UE cannot access the network.

X



Elements of WCDM A Uplink Budget 20. Slow Fading Margin (dB)

Slow Fading Margin (dB) = NORMSINV (required edge coverage Probability) × Std. dev. of Slow Fading (dB)

Edge Reliability:50% Edge Reliability:75%

Key point: Property of normal distribution

Elements of WCDM A Uplink Budget  21. SHO Gain over Slow Fading (dB)  ± The soft handover gain includes two parts:  Multiple irrelevant soft handover branches lower  the required margin for fading, which results in multi-cell gain  Gain for the link demodulation of the soft handover ±macro diversity combination gain

 ± The SHO Gain over Fast Fading refers to the macro diversity combining gain  ± Obtained through simulation

Elements of WCDM A Uplink Budget

 Summary: path loss at the edge of a cell  ± Based on the maximum path loss allowed by the link, the path loss at the edge can be calculated if the fading margin and soft handover gain for providing the required edge/area coverage probability and the penetration loss of indoor coverage are considered.

 ± Path Loss (dB) = EiRP (dBm) + SHO Gain over Slow Fading (dB) - Minimum Signal Strength Required (dBm) - Penetration Loss (dB) - Slow Fading Margin (dB)

Summary of the Uplink budget

Path Loss

EIRP

UE 

+ SHO Gain over Slow Fading

Power ± Body Loss a_ UE_Antenna

- Slow Fading Margin

f(edge coverage Probability) * Std. dev. of Slow Fading

- Penetration Loss

- Minimum Signal Required

Sensitivity of Receiver -

-

Gain

SHO Gain

over fast fading

of Antenna + Fast Fading Margin + Body Loss +

Interference Margin + Margin for Background Noise

Margin for Background Noise = 10log (10X /1010Y/10) dBmX dBm

standard deviation of path loss outdoor : X dB,

Sensitivity of Receiver= PN + required Eb/No ± Processing Gain

standard deviation of Penetration Loss: Y dB,

PN = 10lg ( K*T*B*Nf ) = -108 (dBm/3.84MHz) + NF (dB) ; NF is the receiver NF

Std. dev. of Slow

Fading = Sqrt(X2 + Y2)

of the receiver system at the antenna connecter  Processing Gain = 10lg[3.84Mcps/Rb(Kbps)] So

the Sensitivity of Receiver =

- 174

(dBm/Hz) + NF (dB) + 10lg[Rb (bps)] + Eb/No (dB)

Contents 1. Process of WCDM A Network Planning 2. Uplink Budget 3. Downlink

Budget

4. Coverage Enhancement Technologies

Fundamental Principle NodeB

TX

Ga _BS

Pout_BS Lf_BS Lc _BS Combiner  Duplexer 

Feeder 

RX

Ga _UE UE Fading Mar gin

Pout_UE TX

Combiner  Duplexer  Body Loss RX

Penetr ation Loss

 Algorithm

 Downlink (forward)

 PL_DL=Pout_BS ± Lf_BS + Ga_BS + Ga_UE + Ga_SHO ±Mpc± Mf ± MI ± Lp ± Lb ± S_UE  PL_DL: Maximum propagation loss of the downlink  Pout_UE: Maximum transmit power of the traffic channel of the BS  Lf_BS: Cable loss  Ga_BS: Antenna gain of the BS; Ga_UE: Antenna gain of the UE  Ga_SHO: Gain of soft handover   Mpc: Margin for fast power control  Mf: Slow fading margin (related to the propagation environment)  MI: Interference margin (related to the designed system load)  Lp: Penetration loss of a building (for indoor coverage



Elements of WCDM A Downlink  Background Noise Max Power of  Budget TCH

 Cable Loss  Gain of BS Tx  Antenna  EIRP  Gain of UE Rx  Antenna

Level  SHO Gain over Fast Fading  Fast Fading Margin  Minimum Signal Strength Required  Penetration Loss

 Std. dev. of Slow Fading  Noise Figure (UE)  Required Eb/No  Edge coverage  Body Loss



Elements of WCDM A Downlink Budget Downlink Cell Load Downlink cell load factor is defined in two ways:  ± 1. Downlink cell load factor at the receiver:

« L D ! §¬1E j 1  N 

 L

» i j   b/ N o j   v j ¼ W  ½  j

 ± This definition is similar to that of the uplink cell load:  The higher the downlink cell load, the higher the cell transmit power, and the higher the receiver  interference.  When the downlink cell load is 100% , the corresponding capacity is the limit capacity of the downlink.