Link budget planning is part of the network planning process, which helps to dimension the required coverage, capacity and quality of service requirement in the network. UMTS WCDMA macro cell coverage is uplink limited, because mobiles power level is limited to (voice terminal 125mW). Downlink direction limits the available capacity of the cell, as BTS transmission power (typically 20-40W) has to be divided to all users. In a network environment both coverage and capacity are interlinked by interference. So by improving one side of the equation would decrease the other side. System is loosely balanced by design.

The object of the link budget design is to calculate maximum cell size under given criteria:

# Type of service (data type and speed)# Type of environment (terrain, building penetration)# Behavior and type of mobile (speed, max power level)# System configuration (BTS antennas, BTS power, cable losses, handover gain)# Required coverage probability# Financial and economical factors (use of more expensive and better quality equipment or not the cheapest installation method)

and to match all of those to the required system coverage, capacity and quality needs with each area and service.

In an urban area, capacity will be the limiting factor, so inner city cells will be dimensioned by required Erlangs/km² for voice and data.Even using 25dB as inbuilding penetration loss into the building core area, link budget would typically allow about 300m cell range, which is a way too much for a capacity purposes. In a rural area uplink power budget will determine the maximum cell range, when typically cells are less congested. A typical cell range in rural areas will be several kilometers depending on a terrain.

Below is an example of how WCDMA voice call link budget can be done. Some of the values can be debated, including the propagation model, but it gives an idea of the calculation methods.

The WCDMA link budget calculations start from the uplink (reverse link) direction. Uplink interference (noise from other mobiles) is usually the limiting factor in cdma systems.

1.>The starting point of a link budget calculation is to define the required data rate(s) in each network areas and Eb/No (Energy per Bit to Noise power density ratio) targets. Usually the operator predefines these, but simulation tools can be used to tailor the Eb/No. Simulation can be done by creating a uniform base station and a mobile distribution plan with defined service profiles. Almost every UMTS vendor has a simulation tool for operators to test their network plan models.

2.> The next step is to gather vendor specific data like a BTS output power and a receiver noise figure, defined and used cable systems (thicker the cable, more expensive it is to install), used antenna types, usage of intelligent antenna systems in specific areas, possible additional line amplifiers, used diversities (like antenna, polarisation, receiver) etc.

3.>For each geographical areas network operator has to define Eb/No, data services, a system loading factor, estimated mobile speeds, different penetration losses, coverage reliability and a used fade margin. Soft handover area sizes will be addressed later.

4.> Mobile power levels, the chip rate and the process gains are defined by the UMTS standards. Soft handover gain and the thermal noise density are the same in every UMTS system. Both parties also have to agree on propagation models after drive tests.The link budget gives a cell range and from that cell coverage area can be calculated. Cell coverage overlap parameter is usually missing from the calculation as it increases the cell count dramatically. Most network planners agree that overlap should be 20-30 percent, but that relates directly to build cost. After all that, the base station requirements for the each type of areas can to be calculated.

Link budget planning is part of the network planning process, which helps to dimension the required coverage, capacity and quality of service requirement in the network. UMTS WCDMA macro cell coverage is uplink limited, because mobiles power level is limited to (voice terminal 125mW). Downlink direction limits the available capacity of the cell, as BTS transmission power (typically 20-40W) has to be divided to all users. In a network environment both coverage and capacity are interlinked by interference. So by improving one side of the equation would decrease the other side. System is loosely balanced by design.

The object of the link budget design is to calculate maximum cell size under given criteria:

# Type of service (data type and speed)# Type of environment (terrain, building penetration)# Behavior and type of mobile (speed, max power level)# System configuration (BTS antennas, BTS power, cable losses, handover gain)# Required coverage probability# Financial and economical factors (use of more expensive and better quality equipment or not the cheapest installation method)

and to match all of those to the required system coverage, capacity and quality needs with each area and service.

In an urban area, capacity will be the limiting factor, so inner city cells will be dimensioned by required Erlangs/km² for voice and data.Even using 25dB as inbuilding penetration loss into the building core area, link budget would typically allow about 300m cell range, which is a way too much for a capacity purposes. In a rural area uplink power budget will determine the maximum cell range, when typically cells are less congested. A typical cell range in rural areas will be several kilometers depending on a terrain.

Below is an example of how WCDMA voice call link budget can be done. Some of the values can be debated, including the propagation model, but it gives an idea of the calculation methods.

The WCDMA link budget calculations start from the uplink (reverse link) direction. Uplink interference (noise from other mobiles) is usually the limiting factor in cdma systems.

1.>The starting point of a link budget calculation is to define the required data rate(s) in each network areas and Eb/No (Energy per Bit to Noise power density ratio) targets. Usually the operator predefines these, but simulation tools can be used to tailor the Eb/No. Simulation can be done by creating a uniform base station and a mobile distribution plan with defined service profiles. Almost every UMTS vendor has a simulation tool for operators to test their network plan models.

2.> The next step is to gather vendor specific data like a BTS output power and a receiver noise figure, defined and used cable systems (thicker the cable, more expensive it is to install), used antenna types, usage of intelligent antenna systems in specific areas, possible additional line amplifiers, used diversities (like antenna, polarisation, receiver) etc.

3.>For each geographical areas network operator has to define Eb/No, data services, a system loading factor, estimated mobile speeds, different penetration losses, coverage reliability and a used fade margin. Soft handover area sizes will be addressed later.

4.> Mobile power levels, the chip rate and the process gains are defined by the UMTS standards. Soft handover gain and the thermal noise density are the same in every UMTS system. Both parties also have to agree on propagation models after drive tests.The link budget gives a cell range and from that cell coverage area can be calculated. Cell coverage overlap parameter is usually missing from the calculation as it increases the cell count dramatically. Most network planners agree that overlap should be 20-30 percent, but that relates directly to build cost. After all that, the base station requirements for the each type of areas can to be calculated.

Link budget planning is part of the network planning process, which helps to dimension the required coverage, capacity and quality of service requirement in the network. UMTS WCDMA macro cell coverage is uplink limited, because mobiles power level is limited to (voice terminal 125mW). Downlink direction limits the available capacity of the cell, as BTS transmission power (typically 20-40W) has to be divided to all users. In a network environment both coverage and capacity are interlinked by interference. So by improving one side of the equation would decrease the other side. System is loosely balanced by design.

The object of the link budget design is to calculate maximum cell size under given criteria:

# Type of service (data type and speed)# Type of environment (terrain, building penetration)# Behavior and type of mobile (speed, max power level)# System configuration (BTS antennas, BTS power, cable losses, handover gain)# Required coverage probability# Financial and economical factors (use of more expensive and better quality equipment or not the cheapest installation method)

and to match all of those to the required system coverage, capacity and quality needs with each area and service.

In an urban area, capacity will be the limiting factor, so inner city cells will be dimensioned by required Erlangs/km² for voice and data.Even using 25dB as inbuilding penetration loss into the building core area, link budget would typically allow about 300m cell range, which is a way too much for a capacity purposes. In a rural area uplink power budget will determine the maximum cell range, when typically cells are less congested. A typical cell range in rural areas will be several kilometers depending on a terrain.

Below is an example of how WCDMA voice call link budget can be done. Some of the values can be debated, including the propagation model, but it gives an idea of the calculation methods.

The WCDMA link budget calculations start from the uplink (reverse link) direction. Uplink interference (noise from other mobiles) is usually the limiting factor in cdma systems.

1.>The starting point of a link budget calculation is to define the required data rate(s) in each network areas and Eb/No (Energy per Bit to Noise power density ratio) targets. Usually the operator predefines these, but simulation tools can be used to tailor the Eb/No. Simulation can be done by creating a uniform base station and a mobile distribution plan with defined service profiles. Almost every UMTS vendor has a simulation tool for operators to test their network plan models.

2.> The next step is to gather vendor specific data like a BTS output power and a receiver noise figure, defined and used cable systems (thicker the cable, more expensive it is to install), used antenna types, usage of intelligent antenna systems in specific areas, possible additional line amplifiers, used diversities (like antenna, polarisation, receiver) etc.

3.>For each geographical areas network operator has to define Eb/No, data services, a system loading factor, estimated mobile speeds, different penetration losses, coverage reliability and a used fade margin. Soft handover area sizes will be addressed later.

4.> Mobile power levels, the chip rate and the process gains are defined by the UMTS standards. Soft handover gain and the thermal noise density are the same in every UMTS system. Both parties also have to agree on propagation models after drive tests.The link budget gives a cell range and from that cell coverage area can be calculated. Cell coverage overlap parameter is usually missing from the calculation as it increases the cell count dramatically. Most network planners agree that overlap should be 20-30 percent, but that relates directly to build cost. After all that, the base station requirements for the each type of areas can to be calculated.

Explain the different Handover types in UMTS Ans: Soft(er) Handover: connected to more than one cell on the same frequency, softer occurs when 2 cells in the active set belong to same Node-B; Intra-frequency Hard Handover: Occurs when Ue moves from one cell in one RNC to a cell in another RNC and the RNCs do not have an Iur link between each other; Inter-Frequency Hard Handover: when UE changes from one frequency to another frequency (usually due to traffic layer management or Quality reasons);Inter-technology (iRAT) Hard Handover: Handover from UMTS to GSM (v.v.) usually at the edge of UMTS service area but also due to quality reasons.

Explain the different Handover types in UMTS Ans: Soft(er) Handover: connected to more than one cell on the same frequency, softer occurs when 2 cells in the active set belong to same Node-B; Intra-frequency Hard Handover: Occurs when Ue moves from one cell in one RNC to a cell in another RNC and the RNCs do not have an Iur link between each other; Inter-Frequency Hard Handover: when UE changes from one frequency to another frequency (usually due to traffic layer management or Quality reasons);Inter-technology (iRAT) Hard Handover: Handover from UMTS to GSM (v.v.) usually at the edge of UMTS service area but also due to quality reasons.

Simplified link budget for WCDMA system Edited By @ : Anjit

Target load 0.75

Transmitter characteristics Total transmitter power 20 W 50

Transmitter power on TCH 5.6666667 W 14.1666666667

TX PWRTCH in dBm 37.533277 dBm 41.5126767533

TX antenna gain 17.425308 dBi

TX cable loss 2 dB

TX Body loss 0 dB

52.958584 dBm

Receiver characteristics RX antenna gain 0 dBi

and margins Thermal noise density -174 dBm/Hz

Receiver noise figure 8 dB

Receiver noise density -166 dB

Receiver noise power -100.15669 dBm

Processing gain 10 dB

Required Eb/No 7 dB

Interference margin 6.0205999 dB

Required signal power -97.136088 dBm

RX Cable loss 0 dB

RX Body loss 0 dB

Diversity gain 0 dB

Fast fading margin 0 dB

Soft handover gain 1 dB

Coverage probability (cell edge) 0.9

Shadow fading std deviation 6 dB

Shadow Fading Margin 7.5 dB

Indoor penetration loss 20 dB

Allowed propagation loss 123.59467 dB

UL allowed Prop Loss = Tx EIRP + RX Ant Gain - Reqd Signal Pwr - RX Cable loss + RX Body loss + Diversity Gain - fast fading margin + Soft Handover Gain - Shadow Fading Margin - Indoor penetration loss

Shadow Fading Margin (cell edge approach) Given coverage probability on cell edge (P)Shadow fading standard deviation1-PClosest 1-P in tableArgument (inverse of Q)Shadow fading margin

Antenna Gain Horizontal 3dB beam width 65Horizontal gain 7.4937950781Number of dipoles 6Vertical gain (dBd) 7.7815125038

384kbps data, DL

Transmitter EIRP

DL allowed Prop Loss=Tx EIRP + RX Ant Gain - Reqd Signal Pwr + Diversity gain - Fast fading margin + Soft handover gain

Vertical gain (dBi) 9.9315125038Total antenna gain 17.425307582

Range (Okumura-Hata path loss model)Carrier frequency 2100

L=137.4+35.2LogR BS antenna height 25MS antenna height 1.5Parameter A 46.3Parameter B 33.9Parameter C 44.9MS antenna gain function (large city) -0.000919047Path loss exponent 3.5743492943Path loss constant 137.33512605Downlink range 0.412649827Uplink range 0.328429832Cell range 0.328429832

Watt

Edited By @ : Anjit 50

0.5

0.25 W

0.25 W TX PWRTCH=0.85*TxPwr/(Max no. of user*Target Load)

23.9794 dBm TX PWRTCH,dBm= 10*log10(TX PWRTCH/0.001)

0 dBi

0 dB

0 dB

23.9794 dBm Tx-EIRP = TXPWRTCH+Tx AntGain-TX cable Loss-Tx body Loss

17.425308 dBi

-174 dBm/Hz

5 dB

-169 dB Rx Noise Density=Thermal Noise Density+ Rx Noise Figure

-103.15669 dBm Rx Nise Pwr = Rx Noise Density+10*log10(3840000)

10 dB PG=10*LOG10(3840/384)3 dB

3.0103 dB Interfernce Margin = -10*LOG10(1-Target Load)-107.14639 dBm Reqd Signal Pwr = Rqd Eb/No-PG+Rx Noise Pwr+Interfrnce margin

2 dB

0 dB

3 dB

4 dB

2 dB

0.9

6 dB

7.5 dB

20 dB

120.0511 dB

UL allowed Prop Loss = Tx EIRP + RX Ant Gain - Reqd Signal Pwr - RX Cable loss + RX Body loss + Diversity Gain - fast fading margin + Soft Handover Gain - Shadow Fading Margin - Indoor penetration loss

0.9 1-P(=Q)6 dB 0.5

0.1 0.40.1 0.3

1.25 0.227.5 dB 0.17

0.10.070.04

0.023degrees 0.01dB

dBd

384kbps data, UL

Fast fading margin + Soft handover gain - Shadow Fading Margin - Indoor penetration loss

dBidBi

UnitMHzmm

dBkmkmkm

dBm

46.9897000433602

We compute TX power on TCH by using the formula

P_tx_ch = (1-control overhead) x Total power / (Load x maximum number of users)

For 384kbps speech service maximum number of users is round

0.13W=21dBm (msTX Pwr)

mW= 10*log10(mW) dBm

Higher the P.G, Better the Service(384k,64k..) Coverage

UL allowed Prop Loss = Tx EIRP + RX Ant Gain - Reqd Signal Pwr - RX Cable loss + RX Body loss + Diversity Gain - fast fading margin + Soft Handover Gain - Shadow Fading Margin - Indoor penetration loss

20W=43dBm (NodeBTXPwr)

PG=10log(Wc/Rb) Wc=3.84Mcps >> Rb= 12.2K for Voice : 64K for Video

0 0.5 1 1.5 2 2.5 3 3.5 410

-5

10-4

10-3

10-2

10-1

100

x

Q(x

)

0 0.5 1 1.5 2 2.5 3 3.5 410

-5

10-4

10-3

10-2

10-1

100

x

Q(x

)

4

0 0.5 1 1.5 2 2.5 3 3.5 410

-5

10-4

10-3

10-2

10-1

100

x

Q(x

)

0 0.5 1 1.5 2 2.5 3 3.5 410

-5

10-4

10-3

10-2

10-1

100

x

Q(x

)

QoS SF SIR(required) CE User/cellVoice CS12.2K 128 2.87 1 30 30

Video CS64K 32 2.5 4 10PS64K 32 2.5 8 20

PS128K 16 5 0 0PS384K(QPSK) 8 10 0 0

HSDPA(16QAM) 16

ZTE CECarrier unit 1 BPC card :> No. of CE in UL: 192

No. of CE in DL: 192

PG=10 logWc/Rb

-5.020286063072

CE is the H/W resource Digital Signal processing(DSP) to process signalling inside the BPC

Wc= 3.84McpsRb=12.2k for voice 64k for video 14.4 Mbps for 15 codes 7.2 Mbps for 10 codes 3.6 Mbps for 5 codes

CE is the H/W resource Digital Signal processing(DSP) to process signalling inside the BPC

Rule of Thumb: Normal ConditionHigh paging & Signalling Load (like registration/update cell)Avoid in LAC Border in High Traffic AreaInputs for LAC Division

# No. of Sites supported by 1 RNC Required No. of sites( from Calculation)1 315 620

1 RNC means >>> 1LAC & 1RAC : as 315 sites supported by 1 RNC1 RNC >> 2-3 LAC,RAC

KPI:RRC connection Req. with serviceKPI:RRC connection Req. with service+update

No. of RNC Required1.96825396825397

WCDMA

increasing the cell load, cell coverage area becomes smallerlimited by interference in ULlimited by Power in DL

The operator normally asks vendors to guarantee the level ofcoverage for a certain load level, using the minimum amount of base stations and cost. Vendorshave to commit to these figures even when most of the sites are yet to be acquired and some ofthe performance parameters will be defined later. Vendors are expected to reply in a very shortperiod of time with limited information, so it is easy to see why network quality is not thebiggest consideration in initial planning. There is a tendency for operators to use this tactic toget the lowest possible initial quote from vendors.An experienced network planner can produce a "quick and dirty" network base stationrequirement figure with only a few parameters. The most crucial parameters for the initial rolloutare:

network (with BTS site capacity calculation) should be known in order to get the requiredamount of base stations for capacity.

order to estimate the required base station amount in each network area to get the amount ofbase stations for coverage.

In each network area, take the larger number of capacity OR coverage base stations for thatarea, then add each area together to get a total. To get the final required number of basestations, the following formula can be used:- Add 10% more quality sites to provide special coverage or a dominant server in difficult orimportant areas - tunnels, bridges, exhibition and sports venues, shopping centres, airports, bighotels, high rise buildings, MD's home and CEO sailing and polo club!- Add additional 10% more sites to fix holes because not all planned sites can be acquired.- By this time the sales team will tell you that your plan is 30% too expensive, so you need tocut 30% of your base stations (and 40% of your acquisition budget)The total will tell you how many sites you need to build an initial 3G network.

Capacity requirements - the planned customers and service usage in each area of the

Coverage requirements - the link budget of high data rate services should be calculated in

A.Coverage Planning : The propagation predictions for WCDMA require the same planning phases as in GSM. First, the base station configuration and the link budget have to be defined. Also, the coverage threshold has to be well defined to exceed the required quality criteria but avoid unnecessary additional investments for the radio network elements. Moreover, the capacity targets and forecasts have to be well known at this phase because they have a strong effect on the base station coverage area. When the base station antenna height, coverage threshold, and capacity requirements are defined and tclarified in the link budget calculations, the actual propagation predictions process can start. Propagation measurements can be performed to fine tune the propagation prediction model. When the prediction model is tuned, the final base station parameters can be used to make the propagation predictions. Optimized base station parameters can be evaluated when the planning criteria are defined. This planning threshold means that agreement must be reached on the reasonable QoS level required for the different geographical locations. The threshold also depends on whether the service has to be extended inside vehicles and buildings in different areas. The planning threshold is defined in GSM by starting from the mobile station senplanning terrain bin.

Capacity Planning WCDMA capacity planning is directly related to the link budget and, thus, to the base station coverage area. In the link budget in Table 1, only one type of service (64/144 kbps data transmission) was introduced, and the base station coverage was fixed for this service. It is possible to have any type of service between the voice calls and 2 Mbps data traffic in the WCDMA Base station. This means :>>> the BASE STATION coverage area is different for different users

Basically, the question is about the spreading power factor, SPF, which varies significantly when comparing the 12.2 kbps voice call (SPF = 25 dB) and 2 Mbps data transmission (PG = 2.8 dB) connections. In the uplink direction, the main objective in capacity planning is to limit interference from the other cells to an acceptable level. Network planning can increase the uplink load by reducing other cell interference. This can be achieved by obstacles to block the interfering cells. Also, down-tilting is a very useful tool in limiting interference. In the downlink direction, two aspects should be considered: the interference from other cells and the power of the base station. The load equation for the downlink is similar to the equation for the uplink. However, in the downlink there is a new para

Spreading Code

Distinguishes physical and logical Channels(service)

Scrambling Code(PSC)

Distinguihes Cells (in DL) and distinguihes UE(in DL)

The number of installed transceivers limits the mobile network theoretical capacity. In cdmasystems interference, accepted and planned quality and grade of service will determine the

interlinked.System capacity planning is divided to two parts:

capacity. Depending on the parameter values, planned transceiver capacity is typically from 400

verify rough estimations. A lot of data is required for comprehensive network dimensioning;number of subscribers and growth estimations, traffic / user / busy hour / geographic segmentand required throughput including service mixes in geographic segments for example.

Here is a rough downlink capacity calculation example:During a busy hour an average user downloads 10 Mbits with 384 kbits/s, 2 Mbits with 144kbits/s and makes one 60-second voice call. Data has to be retransmitted 1.1 times because ofnetwork conditions.Used kbits/s per user per busy hour downlink only are:

If a cell capacity is estimated to be 500 kbits/s, each cell can be dimensioned for about 129

Effective traffic = User traffic / (1-p),(where p is the loss probability) considering the fact that retransmissions may take place more than once.

system capacity. Cdma systems also have soft capacity, which complicates the network areacapacity estimations. The link budget is used to calculate the maximum allowed path loss andthe maximum range for cell. The link budget includes the interference margin, which is theincreased noise level caused by greater load in a cell. So by increasing the cell load, cellcoverage area becomes smaller. That's how cell coverage and capacity dimensioning are

1> The first thing is to estimate a single transceiver and site capacity. Calculations how thenoise raises as the cell load increases is out of the scope of this page, but in-cell noise, Eb/Norequirements, planned data rates, coverage probability, air resources usage activity factor, targetinterference margin and processing gains are needed to approximate the transceiver and site

kbits/s to 700 kbits/s per transceiver.

2> The second part of the process is to estimate how many mobile users each cell can serve.Once the cell capacity and subscriber traffic profiles are known, network area base stationrequirements can be calculated. Estimations can be done in Erlangs per subscriber or kilobitsper subscriber. Network vendor normally has simulation tools to test system parameters and

Estimate/approxiamating Single Transceiver and site capacity:Cell Noise

Eb/No requirementsplanned data rates

coverage probabilityAir resources usage activity factor

target Interference marginProcessing Gains

Estimate how many mobile users each cell can serve:number of subscribers

growth estimations, traffic / user / busy hour / geographic segment Simulation tool(ATOLL) is used :required throughput including service mixes to test system parameters

to verify rough estimations