01 coverage and capacity of gsm system

Huawei Technologies Co., Ltd. Huawei Confidential

Coverage and Capacity

of GSM System

GSM&UMTS Pre-sales RNP Department

Huawei Technologies Co., Ltd.

The planning for the radio network mainly involves

coverage and capacity. The coverage planning

involves radio propagation and hardware model.

The capacity planning involves channel

configuration and location area planning. This

course describes the preceding contents.

Foreword


Cell Radius

No. of BTS TRX

Configuration

Subs. per BTS

Abis Configuration

…

Inputs

Coverage Related

－Coverage Region

－ Area Type Information

－Propagation Condition

－Location Probability

Capacity Related

－Spectrum Available

－Subscriber Growth Forecast

－Traffic Density

－Blocking Probability

BTS Quantity

Capacity Requirement

Configuration

per BTS

Outputs

Overview

C3Q

� Coverage, Capacity, Quality & Cost

GSM Dimensioning Flow

Capacity

Quality Coverage

COST


Capacity DimensioningCapacity Dimensioning

Coverage DimensioningCoverage Dimensioning

• Max Path Loss

• Propagation Model

• Coverage Dimensioning


Link Budget

Cell radius

EIRP

Receive Sensitivity

Max. Path Loss

Propagation Model

Cell Radius


Max Path Loss

MS Transmit Power

MS Antenna Gain

BTS Antenna Diversity Gain

Slow fading margin

Interference margin

Body Loss

Feeder Loss

Penetration Loss

Maximumallowable path

loss

UPLINK BUDGET

BTS Rx sensitivity

Gain

Margin

Loss

TMA Gain (optional)

BTS Antenna Gain

Path Loss

BTS

Sensitivity

MS Transmit power

Uplink Budget


Max Path Loss

BTS Transmit Power

MS Antenna Gain

BTS Antenna Gain Slow fading margin

Interference margin

Body Loss

Feeder Loss

Penetration Loss

Maximum

allowable pathloss

DOWNLINK BUDGET

MS Rx sensitivity

Gain

Margin

Loss

Combiner Loss

TMA Insertion Loss (optional)

Path Loss

BTS

Transmit power

MS Sensitivity

Downlink Budget


Max Path Loss

Path Loss - Loss between BTS antenna and MS antenna

Max. allowable P-loss

MS Rx sensitivity

BTS Rx sensitivity

Body loss

Slow fading margin

Penetration loss

TMA gain

Name

JCBTS antenna gain

KDMS antenna gain

LEBTS antenna div. gain

MFBTS combiner loss

NGBTS Feeder loss

IBMS Tx Power

HABTS Tx Power

ItemItemName

Uplink:

B + D – K – I – J – N + E + C (+ H) – G = L

Uplink:

B + D – K – I – J – N + E + C (+ H) – G = LDownlink:

A – F – G + C – N – I – J – K = M

Downlink:

A – F – G + C – N – I – J – K = M


MS/BTS Tx Power & Rx Sensitivity

MS

� Typical Tx Power: 2w (33dBm)@900MHz; 1w(30dBm)@1800MHz

� Typical Rx Sensitivity: -102dBm (for planning)

BTS

Max Path Loss

http://3ms.huawei.com/mm/docMaintain/mmMaintain.do?m

ethod=showMMDetail&f_id=GSM200810200035

45W(GMSK)/30W(8PSK)60W(GMSK)/40W(8PSK)Transmitter power

-113dBm-112.5dBmReceive Sensitivity

BTS3900(DRFU 900M)BTS3012(DTRU 900M)


Max Path Loss

Combiner Loss

TOC Output Power =

Transmitter Output Power – Combiner Loss – Duplexer Loss – Connector Loss

DPX

RXDI

DPX

RXDI

TR

X1

TR

X2

CO

M

ANTA ANTB

DPX

RXDI

DPX

RXDI

TR

X1

TR

X2

CO

M

TR

X3

TR

X4

CO

M

ANTA ANTB

BTS3012

Output 47.8dBm@900M

DCOM 3.3dBm@900M

DDPU 0.8dBm@900M

Connector 0.2dBm


Max Path Loss

Feeder Loss in Link Budget includes:

--- Feeder loss b/w BTS and antenna

--- Jumper Loss b/w BTS and antenna

--- Connectors loss b/w BTS and antenna

Feeder Loss

4.31dB/100m5.87dB/100m16.1dB/100m1800M

2.98dB/100m4.03dB/100m11.2dB/100m900M

5/4 inch7/8 inch1/2 inch

lightening arrester

Jumper between

Antenna

TTA

Antenna stand

Jumper between antenna and TTA

Jumper between TTA and feeder

Feeder

Lightening arrester

and cabinet


Max Path Loss

� Typical gain:

� Omni: 11dB

� Directional: 18 dB

� In-building: 2dB

Antenna Gain

� Receive diversity gain:

� 2 way receive diversity: 3dB

� 4 way receive diversity: 6dB


Max Path Loss

Technical Theory of TMA

� TMA is to reduce the noise figure of BTS, so as to improve the

sensitivity of BTS.

TMA Affect link budget

� Improve uplink

� Generally, the TMA gain can be calculated as to against feeder loss

between BTS and TMA.

� Worsen downlink

� Introduce insertion loss (0.5~1

dB) to downlink

Affect the Stability of network

TMA


Slow fading (long term fading)

Fast fading (short term fading)

� Caused by multi-path propagation

� Fast fading margin: 3dB

Max Path LossFading Margin


Max Path Loss

Slow Fading

� Signal levels obey Log-Normal distribution

Slow Fading Margin depends on:

� Area Coverage Probability

– The higher coverage probability is, the more SFM required

� Standard Deviation

– The higher standard deviation is, the more SFM required

Received Signal Level [dBm]

Pro

ba

bili

ty D

en

sity

Fmedian (x)Fthreshold

Coverage Probability:

P COVERAGE (x) = P [ F(x) > Fthreshold ]

Coverage Probability:

P COVERAGE (x) = P [ F(x) > Fthreshold ]σσσσ

SFM required

Fading Margin


Max Path Loss

Building Penetration Loss

� Relate to frequency and building character

� Frequency ↑ � Penetration loss ↑

� Wall: 5~30 dB (concrete / brick / wood / …)

� Glass / Car: 6~10 dB

� Elevator: ~30dB

� ……

X dBmW dBm

Penetration Loss=X - WPenetration Loss=X - W

888Highway

10~1814~2016~23Urban

8~1410~1611~19Suburban

2~3Body loss

6~1288Rural

14~2218~2518~28Dense urban

450 MHz800/900

MHz1.8/1.9/2.1

GHzScenario

Frequency

� Typical penetration loss value (dB)

E1

θ

θ

DW1 W2

E2Penetration Loss & Body Loss


Max Path Loss

Path Loss

Max. allowable P-loss

MS Rx sensitivity

BTS Rx sensitivity

Body loss

Slow fading margin

Penetration loss

TMA gain

Name

JCBTS antenna gain

KDMS antenna gain

LEBTS antenna div. gain

MFBTS combiner loss

NGBTS Feeder loss

IBMS Tx Power

HABTS Tx Power

ItemItemName

Uplink:

B + D – K – I – J – N + E + C (+ H) – G = L

Uplink:

B + D – K – I – J – N + E + C (+ H) – G = LDownlink:

A – F – G + C – N – I – J – K = M

Downlink:

A – F – G + C – N – I – J – K = M

� EiRP: Equivalent isotropic Radiation Power

� (BTS) EiRP = A – F – G + C

� (MS) EiRP = B + D




• Max Path Loss




Propagation Model

� Tradition model is an empirical mathematical formulation

� describe radio wave propagation as a function of frequency, distance,

antenna height and other conditions.

– Path Loss = f (frequency, distance, antenna height, etc.)

� The model is usually used to predict the behavior of propagation

for all similar links under similar constraints.

� Predict the path loss along a link or effective coverage area of a transmitter.

What is Propagation Model


Propagation Model

� Okumura/Hata

� Frequency: 150~1500 MHz

� Distance: 1~20 Km

� Tx antenna height: 30~200m

Lp = 69.55 + 26.16*lg(f) − 13.82*lg(Hb) + [44.9 − 6.55*lg(Hb)]*lg(d) − a(Hm) − Cm

• a(Hm) = [1.1*lg(f) – 0.7]*Hm – [1.56*lg(f) – 0.8] (for city)

• Cm = 0 (for urban area)

= 2*[lg(f/28)]2 + 5.4 (for suburban area)

= 4.78*[lg(f)]2 – 18.33*lg(f) + 40.94 (for open area)

Lp = 69.55 + 26.16*lg(f) − 13.82*lg(Hb) + [44.9 − 6.55*lg(Hb)]*lg(d) − a(Hm) − Cm

• a(Hm) = [1.1*lg(f) – 0.7]*Hm – [1.56*lg(f) – 0.8] (for city)

• Cm = 0 (for urban area)

= 2*[lg(f/28)]2 + 5.4 (for suburban area)

= 4.78*[lg(f)]2 – 18.33*lg(f) + 40.94 (for open area)

� Cost231/Hata

� Frequency: 1500~2000 MHz

� Distance: 1~20 Km

� Tx antenna height: 30~200m

Common Models


Propagation Model

� U-Net SPM model

� Based on Hata model

� Suitable for more macro cell scenarios

� Be used to do coverage prediction and simulation by software

Lp = K1 + K2 * lg(d) + K3 * lg(Hb) + K4 * Diffraction_loss + K5 * lg(d) * lg(Hb)

+ K6 * Hm + Kclutter * f(clutter)

• K1, constant, relate to frequency

• K2, distance factor, show the speed of signal fading along with distance

• K3, affect the relation between path-loss and transmitter antenna height

• Diffraction_loss, according to the selected diffraction algorithm

• f(clutter), avg. clutter loss according to the digital map

Lp = K1 + K2 * lg(d) + K3 * lg(Hb) + K4 * Diffraction_loss + K5 * lg(d) * lg(Hb)

+ K6 * Hm + Kclutter * f(clutter)

• K1, constant, relate to frequency

• K2, distance factor, show the speed of signal fading along with distance

• K3, affect the relation between path-loss and transmitter antenna height

• Diffraction_loss, according to the selected diffraction algorithm

• f(clutter), avg. clutter loss according to the digital map

Typical Propagation Models


Propagation Model

Why

� Propagation environment is very complicated

� No universal model

� It’s necessary to calibrate the model based on the on-site test

How

� On-siteTest

� CW (Continuous Wave) test

– Accurate but high cost (money and workload)

� Existing telecommunication network DT

� Calibrate the model by software (U-Net)

Model Tuning




• Max Path Loss




Coverage Dimensioning

� Path Loss = f (frequency, distance, BTS antenna height)

� Allowable max. path loss, calculated through link budget

� Frequency, confirmed

� BTS antenna height, designed according to:

� Distance, i.e. cell radius, can be figured out

Cell Radius

UL/DL Balance

� Balance or Not?

� Cell radius? UL or DL?

UL DL

Difference:

• BTS/MS Tx power

• Tx Combiner loss

• BTS/MS Rx

sensitivity

• Rx diversity gain

• UL/DL Frequency

• TMA gain


Coverage area of single site

Distance between 2 sites

� Normal site: D = 1.5 * R

� Highway site: D = 2 * R


RR

23

8

9RArea =

23

2

3RArea =

• 3-cell site with 65-degree H-BW antenna

• Omni site• 3-cell site with 90-

degree H-BW antenna

D

R

Coverage Area of Single Site



Coverage Requirement

� Total coverage area: XXX Km2

� Divided into several scenarios

� CBD, Dense urban, Urban, Suburban, Rural, Highway, etc.

� Area of each scenario

BTS Quantity Dimensioning

� Except for highway:

� Highway:

∑=Site Singleof AreaCoverage

Scenario Eachof AreaTotalQuantity BTS

∑=Site Singleof Radius Cell * 2

Highwayof Length TotalQuantity BTS

BTS Quantity Dimensioning



Shortcoming of Dimensioning

� Too simple, based on the theoretic calculation only

� Lack of consideration of actual situation

� Scrambling of coverage area

� Unnecessary area

� Possibility of sites acquisition

� ……

How to improvement

� Field survey

� Terrain, scenario division, buildings, population, existing networks, …

� Lay out BTS depends on both dimensioning and map

� Digital map, GoogleEarth, traditional map, photographs, …

BTS Layout




• Max Path Loss




Capacity Dimensioning

Capacity Planning Process

Coverage area per Site

Traffic model

Distribution of Subscribers

Traffic Load per Site

TRX/Channel/…Configuration

Limitation Judgment

Figure out the max. configuration

Frequency Planning

END

Coverage

limitation

BTS Quantity

Capacity

limitation


GoS

Erlang-B



Traffic Model

Traffic refers to the usage of channels and is usually thought as the holding time per time unit for

one or several circuits.

Erlang

Erlang (E) is the unit of measurement for traffic intensity.

Measure of Traffic: 1 Erlang = 1 Call with duration 1 Hour

A = n x T / 3600 Erlang

where,

A = offered traffic from one or more users in the system

n = number of calls per hour

T = average call time in seconds

Key Factor: Traffic Model



GoS (Grade of Service)

It is the probability of a call in a circuit group being blocked or delayed for more than a specified

interval.

For a Lost Call system, the GoS can be measured using such equation:

calls offeredof Number

callslost of NumberServiceof Grade =

Key Factor: GoS



Key Factor: Erlang-B



How many 3 sectored sites needed for Area X if

Traffic per subscriber = 25mE

Number of Subscribers = 10,000

Max Configuration of BTS is S222

GoS = 2%

Answer:

Traffic channels per Cell = 2 x 8 –1 (Control Channels) = 15 TCH

Traffic per cell = 15 TCH with 2% GoS = 9.01Erlangs (from Erlang’s B Table)

The number of subscribers per cell = 9.01 E / 25 mE = 328

No of cells needed = 10,000 / 328 = 28 cells

No of 3 sector sites needed = 10

Example

Thank youwww.huawei.com

01 coverage and capacity of gsm system

Documents

capacity dimensioningkey

signal fading

receive diversity

ijjn

coverage probability

cell radius

feeder loss

open area