erl tableb

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Post on 31-Dec-2015




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Dear Thomas,

1. In CDMA 1X system if we want to know the number of subscribers (customers) supported by one BTS we need to know TRAFFIC MODEL (essential). This traffic model can be supplied by Customer (if there is a formal tender/bidding) or we can use our Default traffic Model. The traffic model describes the behavior of the subscriber in the network according to the different environments.

For example, the Huawei default traffic model is:


Voice Service Traffic Model

Grade of Service (GOS), Radio Channel2%

Voice Activity Factor0.4

Mobile CustomersProportion of mobiles in entire network90%

Busy hour traffic per customer0.08Erl

FWT CustomersProportion of FWTs in entire network10%

Busy hour traffic per customer0.08Erl

Cell Loading50%

Soft Handoff Ratio30%

1x Data Service Traffic Model

Data service subscribers distributionHigh-end subscribers15%

Middle subscribers25%

Low-end subscribers60%

Data service model parametersPPP Session Time(s)350

PPP Session Duty10%

Access Rate Grade

Grade of Data Rate (kbps)Data Rate (kbps)Statistics Proportion

Low-end MiddleHigh-end








Average (kbps)9.626.1169.60

Mixed Service Traffic Model

Service TypeService Proportion

Voice only90%

Voice and Data10%

Assumptions on Terminal Types

The proportion between MS and FS in the entire networkMS (Mobile)90%

FS (Fixed Terminal)10%

Types of FS's antennaIndoor 50%

Outdoor Directional 50%

Assumptions on Subscriber Action

Subscriber Moving Speed0Km/h3Km/h8Km/h30Km/h100Km/h



Assumptions on radio environment

Shadow Margin


Area Coverage Probability90%90%90%

Marginal Coverage Probability75%75%75%

Shadow fading Margin (dB)

Standard Deviation of Shadow Fading(dB)888

Average BTS Antenna Height


Antenna height (m)304050

Reverse Maximal Transmit Power for R-FCH and R-SCH at Different Service Rate.

R_FCH and R_SCH Maximal Transmit Powers when Convolution Coding is used.

Max Terminal TX Power (mW)200/250

Max Terminal TX Power (dBm)23.01/24

R_FCH Data Rate (kbps)9.6

R_SCH Data Rate (kbps)/9.619.238.476.8153.6

Max R_SCH TX Power (dBm)/19.1720.521.2921.9122.35

Max R_FCH TX Power (dBm)21.5519.1717.8716.1714.0311.1

Feeder Cable Loss for 450M Frequencies Band

Feeder Cable Loss (450MHz)dB/100m

7/8 Feeder Cable2.7

5/4 Feeder Cable1.9

1/2 Jumper7.6

NOTE: RED COLOR MEANS DEFAULT. All those parameter are suitable to be changed by customer request. The coverage area is also important parameter for coverage prediction. 2. After get the traffic model we do the Capacity planning based on that traffic model. There are a lot of calculation, some made by our CDMA2000 Radio Netplan Estimate Tool and other made by your self.

3. According to the calculation result you get the BTS Throughput and the Single user Throughput. So the ratio between the BTS Throughput and the Single user Throughput will give the number of subscribers supported by each BTS. According to environment types the number of user is different from each type of environment. Normally, dense urban environment can accommodate less users compared with suburban, and suburban can accommodate less subscribers than rural and so on.

After that we calculate the Erlang for each environment; what we do for that is:

(a) Voice channel element (Erl) = Total throughput for voice users of single cell / (Voice Rate*Voice activation factor) or = Total voice users in a single cell * Erl value per voice user = A(b) FCH channel element (Erl) = FCH data throughput of single cell / (Basic rate of FCH data) = B

(c) SCH channel element (Erl) = SCH data throughput of single sector / (Basic rate of SCH data* Utilization of data demodulation resource) = C

(d) Total channel element resource with soft handover taken into account = (Voice CE +PTT CE +FCH CE) / (1- Soft handover proportion) +SCH CE = (A + B) /(1-30%) +C= D

(Note: Huawei assume 30% soft handoff percentage.)

(e) Total channels resource (Erl) of each cell =Total CE resource with soft handover taken into account + common access channel resource (1 Erl per sector) = D + 3 = BHT

(f) Number of channels required for configuration =Erl_B (BTS basic CE, service blocking ratio) =Erl_B(BHT, 2%)=N.NOTE: Erl(BHT,2%) is a table where we go on the column 0.02 until find the value BHT, then we read the value of N. see the next figure.

Click here if you have access to the Internet and test the Erl_B table: Now, according to the above explanation I thing that you get the idea why I cannot tell you the number of subscribers supported for each BTS. If you have more information about traffic model I can help you. What you need is only to send me that traffic model.I CAN DO FOR YOU THE CALCULATION USING OUR DEFAULT VALUES, BUT YOU MUST WAIT AT LEST TWO DAYS TO GET THE ANSWER, BECAUSE TOMORROW (13TH DEC) IF I GET SEATE ON PLANE ILL GO BACK TO MAPUTO, OTHERWISE ILL TRY ON WEDNESDAY. SORRY FOR THAT.You can also give a look to our CRNP Estimation Tool. You can see the traffic model sheet and the capacity sheets.

For any question feel free to ask me Ill do my best to give you the right answer!Service blocking ratio (QoS = 2%)

Number of CE



WLL plan & estimate tool

CRP CDMA Network Plan Product Department


Tan Yangbo35100

Dai Zhian35152


2Input Parameter(Number or text)

1Input Parameter(Logical Value)

2Calculation Result

2Default Value





Input Parameters

Single Sector Parameter

Sector Environment1Transmit Power of Base StationW20MS's Max Transmit Power(mw)1.0Upper Limit of Reverse Load80%

System Frequency(MHz)1Forward System Load100%Mobile Antenna Height(m)1.5Low Limit of Reverse Load5%

Coverage Area(km2)1Revervse System Load61%FS's Max Transmit Power(Outdoor Antenna)(mw)1.0Soft Handoff Proportion30%

Subscribers in Cover Area10000Antenna Type of Base Station3Antenna Type of FS(Outdoor)1Traffic of single subscriberErl0.025

Density of Cover Area(people/km2)10000Base Station Antenna Height(m)30.0Feeder Cable Type of FS1.0

Area Coverage Probability6Base Station Antenna Gain(dB)15.0Length of Feeder Cable for FS(outdoor antenna)(m)15.0

Distribution in Sector1Cable Type of Base Station1Outdoor Antenna Height of Fix Station(m)5.0

Forward Noise Floor Correction(dB)0.0Length of Feeder Cable in Base Station(m)30Outdoor Antenna Gain of Fix Station(dB)7.0

Reverse Noise Floor Correction(dB)0.0Paging Channel Num1Indoor Antenna Height of FS(m)1.5

Second Environment Correction(dB)0.0Rate of Paging Channel(bps)9600Indoor Antenna Gain of FS(dB)1.0

System Blocking Percentage2%FER of PDS1FS's Max Transmit Power(Indoor Antenna)(mw)2.0

FER of Voice Service1FER of CDS1Fix Station Need to be continuous covered1

PDS Need Continuous Cover1

Service Distribution

Voice Service Proportion85%CDS Proportion0%

PDS Proportion0%Mixed Service Proportion(Voice+CDS)5%

Mixed Service Proportion(Voice+PDS)10%Mixed Service Proportion(Voice+CDS+PDS)0%100%

PDS Subscribers DistributionData Service Model ParametersAntenna Type of the FS(percentage)Indoor50%

High-end Subscribers15%PPP Session Tiem(s)350Outdoor50%100%

Middel Subscribers25%PPP Session Duty Ratio10%Distrubiton of FS and MS(percentage)MS90%

Low-end Subscribers60%FS10%100%


Moving Speed Distribution




Output Parameters

Coverage Radius of Singel Sector(km)Coverage Area of Single Sector(km2)

MSVoice radius0.390.29MS voice service reverse coverage is limited

PDS Rate(kbps)9.600.25MS PDS reverse coverage is limited

PDS radius0.35

CDS radius0.330.22MS CDS reverse coverage is limited

FSVoice radius0.540.57Indoor FS voice service reverse coverage is limited

PDS Rate(kbps)9.600.49Indoor FS PDS reverse coverage is limited

PDS radius0.50

CDS radius0.440.37Indoor FS CDS reverse coverage is limited

System load61%

MS's Max Transmit Power(dBm)0.00

FS's Max Transmit Power with Outdoor Antenna (dBm)0.00

FS's Max Transmit Power with Indoor Antenna(dBm)3.01

Direct Radiate Distance of Electromagnetic Wave(km)(MS)23.94

Direct Radiate Distance of Electromagnetic Wave(km)(FS with outdoor antenna)27.55

Capacity Per BTS

Base Station TypeS1/1/1

Throughput Per BTS(kbps)(Mixed sector)284.3

Simultaneous Subscribers in Sector32

Configuration of the BTS that Satisfy the Service Analysis

Base Station TypeS1/1/1

Average Throughput Per Subscriber(bps)110.03

Support Subscribers Per BTS2645

BTS support Subscribers2645

BTS Num4

Channel Resource Per BTS(Max Configuration)Channel Resource Per BTS(Satified current configuration)

BTS TypeS1/1/1BTS TypeS1/1/1