network planning.ppt

Prepared by:

Ahmed Mostafa Ramadan

Contents

1.1. Planning basis.Planning basis.

2.2. Coverage planning Coverage planning

3.3. Capacity planningCapacity planning

4.4. Advance planningAdvance planning

5.5. Frequency PlanningFrequency Planning

6.6. Neighbor PlanningNeighbor Planning

GSM BandwidthGSM 900 :

Channel spacing 200kHz,124 carriers

GSM 1800 :

Channel spacing 200kHz,374 carriers

890 915 935 960

Duplex Spacing : 45 MHz

1710 1785 1805 1880

Duplex Spacing : 95 MHz

Requirement for C/I

All useful signals carrierAll useless signals interferenceC/I = =

Useful signalNoise from environment

Other signals

For Co-freq design:Theoretical C / I >= 9 dBPractical C / I >= 12 dB

For Adj-freq design:Theoretical C / A >= - 9 dBPractical C / A >= - 6 dB

Signal Quality in GSM

RX Quality RXQUAL class : 0 ... 7

RXQUAL Mean BER BER rangeclass (%) from... to0 0.14 < 0.2%1 0.28 0.2 ... 0.4 %2 0.57 0.4 ... 0.8 %3 1.13 0.8 ... 1.6 %4 2.26 1.6 ... 3.2 %5 4.53 3.2 ... 6.4 %6 9.05 6.4 ... 12.8 %7 18.1 > 12.8 %

usable signal

unusablesignal

good

acceptable

Interference sources

• Multi-path (long echoes) • Frequency reuse• External interference

Reduce the interference as possible.

Methods for reducing Interference

• Frequency planning• Suitable site location• Antenna azimuth, down tilt and height• Frequency hopping• Power control based on quality

– Evaluate signal level and quality• DTX

– Silent transmission in speech pauses

Cell Evolution

Umbrella Cell5-50KmEarly 80’s

Macro Cell

1-5Km

Mid-end 80’s

Micro Cell

100m-1Km

Mid 90’s

Pico Cell

10m-100m

Mid-end 90’s

Macro Cell Layered Network

Layered Network

High layer station

Middle layer stationMiddle layer station

Indoors stationIndoor station

Indoors station

Low layer stationLow layer station

Low layer stationLow layer station

Indoors station

Macro Cell Network

• Cost performance solution• Suitable for covering large area

– Large cell range– High antenna position

• Cell ranges 2 ..20km • Used with low traffic volume

– Typically rural area– Road coverage

2..20 km

Micro Cell Network

• Capacity oriented network• Suitable for high traffic area• Mostly used with beamed cell

– Cost performance solution– Usage of available site’s equipment

• Typical application– Medium town– Suburb

• Typical coverage range: 0.5 .. 2km

0,5 .. 2km

Radio Link Propagation

• Multi-path propagation Radio path is a complicated propagation medium (Reflection, hills,…..etc)

• Limited transmitting energy The service range is determined by the transmission power of mobiles Battery life-time

• Limited spectrum Set upper limitation for data rate (Shannon´s theorem) Additional effort needed for channel coding Frequency reused result in self- interference

Radio Propagation Environment

• Multi-path propagation• Shadowing• Terrain • Building• Reflection• Interference

Reflections

• Strong echoes can cause excessive transmission delay– No impact If the delay falls in the equalizer window – Cause self-interference if the delay falls out of the

equalizer window

direct signalstrong reflected signal

equalizer window 16 s

amplitude

delay time

long echoes, out of equalizer window:self-interference

Fading• Slow fading (Lognormal Fading)

– Shadowing due to large obstacles on propagation direction• Fast fading (Rayleigh fading)

– Serious interference from multi-path signals

+10

0

-10

-20

-300 1 2 3 4 5 m

Level (dB)

920 MHzv = 20 km/h

Objective of propagation model

• The propagation model is used to estimate the path loss

during radio wave propagation caused by the terrain and

artificial environments

• The propagation model is the foundation of the coverage

planning. A good model mean more precise planning.

• The propagation model depends on the working frequency

of the system. Different propagation models have different

working frequencies ranges. Moreover, indoor propagation

model differs from the out door propagation model

Land Usage Types

• Urban: small cells, 40..50 dB/Dec attenuation

• Forest : heavy absorption; 30..40 dB/Dec; differs with

season (foliage loss)

• Open, farmland : easy, smooth propagation conditions

• Water : propagates very easily ==> dangerous !

• Mountain surface: strong reflection, long echoes

• Hilltops : can be used as barriers between cells, are not used for

antenna or site location

Propagation Model

Propagation model of free space (Lp=32.4+20logf+20logd) Okumura-Hata model (Applying to forecast of 900M macro cell) COST231-Hata model (Applying to forecast of 1800M macro cell) COST231 Walfish Ikegami model (Applying to forecast of 900M and

1800M micro cells) Indoor propagation model (Keenan-Motley, applying to 900M and

1800M cells)

Common propagation models

Propagation losses in free space

Lp=32.4+20lgfMHz+20lgdkm

It can be expressed as:

Ploss=L0+10lgd

=2 path loss slope

Propagation losses in flat area

Lp = 10lgd -20lghb - 20lghm

=4 path loss slope

hb: Height of the BS antenna

hm: Height of the MS antenna

Propagation Models

Okumura-Hata Model

Empirical model Measure and estimate additional attenuations Applied for larger distance estimation (range: 5 .. 20km) Not suitable for small distance ( < 1km)

mhbbp AdhhfL log)log55.69.44(log82.13log16.2655.69

Lp f

bh

mhd

mhA

Path loss (dB)

BS antenna height (m)

MS antenna height (m)

Carrier frequency (MHz)

Distance between the BS and MS (Km)

MS antenna correction factor (dB)

)8.0log56.1()7.0log1.1( fhfA mhm

97.4)75.11(log2.3 2 mh hAm

Middle or small-size cities:

Big cities:

The frequency range is 150MHz to 1500MHz.

Okumura-Hata Model

mhbbp CAdhhfLm log)log55.69.44(log82.13log9.333.46

mCmC ＝ 0dB Large-size cities or central areas of the suburbs

＝ 3dB Big cities

The frequency range is 1500MHz to 2000MHz.

Okumura-Hata Model

Lp=K1+K2lgd+K3(hm)+K4lg(hm)+K5lg(Heff)+K6lg(Heff)lgd+K7diffn+Kclutter

K1- Constant related with the frequency (MHz);

K2- Constant related to the distance (km);

K3, K4- MS antenna height (m) correction factor;

K5, K6- BS antenna height (m) correction factor;

K7- Diffraction correction factor;

Kclutter- Ground fading correction factor;

d- Distance between the BS and MS (km);

hm, Heff- Valid heights of the MS antenna and BS antenna (m)

K Model

In the following table, K and fading values are given. These values are collected during the wave propagation analysis in a medium-size city

K values

K parameter name Parameter value

K1 (MHz)

149/800 (urban), 162.5/2000 (Urban)

145/800 (big city)165.5/2000 (big city)

K2 44.9

K3

-2.49/800(urban)

-2.93/2000 (urban)0/800 (large city,-2.93/2000

(large city)

K4 0.00

K5 -13.82

K6 -6.55

k7h -0.8

Clutter Attenuation

Inland water -3.0

Watery land -3.00

Open areas -2.00

Rangeland -1.00

Forest 13.00

Industrial & commercial area 5.00

Village -2.90

Parallel low buildings -2.50

Suburban -2.50

Urban 0

Dense urban 5

High building 16

Walfish- Ikegami Model• Model used for urban micro-cell propagation. Assume

regular city layout (“Manhattan grid”). Total path loss consists of three parts: Line-of-sight loss LLOS Roof-to-street loss LRTS Mobile environment loss LMS

hw

b

d

What is diversity

Receive diversity provides an effective technique for both overcoming the impact of fading across the radio channel and increasing the received signal to interference ratio

Diversity

Time diversity

Frequency diversity

Space diversity

Polarization diversity

Contents

1.1. PlanningPlanning basisbasis..

2.2. Coverage planningCoverage planning . .

3.3. Capacity planningCapacity planning..

4.4. Advance planning.Advance planning.

5.5. Frequency Planning.Frequency Planning.

6.6. Neighbor Planning.Neighbor Planning.

Cell coverage range

Achievable cell coverage depend on : Frequency band (450, 900, 1800 MHz) Surroundings and environment Link budget figure Antenna type Antenna direction Minimum required signal level

Link Budget

Equipment-related Parameters

• BTS Tx power Maximum BS Tx power.

• Maximum MS Tx power 900:2W 1800:1W

• BS antenna gain Typical value: Omni directional antenna: 11dBi or 13dBi; directional

antenna: 15 to 18dBi.• MS antenna gain

Generally, MS antenna and the connection loss are considered to be 0dB.

Equipment-related Parameters• BTS receiver sensitivity

900:-110dBm 1800:-109dBm The sensitivity is also related with vendor and environment

• MS receiver sensitivity -102dBm

• BTS feeder and connector loss The feeder loss is related to the signal frequency and length. The connector loss is approximately 0.2dB.

Feeder types Frequency 450MHz 800MHz 2000MHz

7/8 inches 2.7 dB/100m 4.03 dB/100m 6.46 dB/100m



Site Coverage Radius: RSite distance: D=1.5RCoverage Area=1.949R2

Site Coverage Radius: RSite distance: D=1.732RCoverage Area=2.598R2

3 – Sectors site Omni site

Distance and Coverage Area

Amount of BTS

• Evaluate achievable cell coverage range Radius=f (topography, requirements, environment, ...) Coverage Area=F (radius) Number of BTS needed for coverage reason

Forecast of Coverage Distance

Principles :

According to the communication probability, obtain the receiving level.

According to the balance of uplink and downlink, estimate the maximum path

loss.

According to the features of environment, confirm the propagation model.

Forecast the coverage distance of cell.

Case

To construct a 900MHz Network in the suburb that requires about

100 square kilometer coverage area, -94dBm minimum receiving

level, and 91% border coverage probability, forecast the coverage

distance and calculate the required quantity of BTSs.

Useful input information• Band: 900MHz• Network environment: suburb • Coverage area: 100km2

• Efficient receiving level: -94dBm• Border coverage probability: 91％


Frequency

Environment

Probability

Level

Required BTS quantity

Coverage acreage

Coverage radius


Contents


2.2. CoverageCoverage planningplanning . .





Basic Knowledge of Capacity Planning

For the capacity planning, you need to know about the following basic concepts:

Traffic

Call exchange volume of a subscriber in a particular time

Another name: traffic load ; Unit: Erlang; where: A – Traffic. m – Number of calls per hour. T – Average call time in seconds.

Block rate ( grade of Service)

When all the channels of a system are occupied, use the following formula to

calculate call loss rate:

Basic Knowledge of Capacity PlanningErlang-B

Capacity Planning

According to the number of subscribers, traffic model, and local

economic situations, forecast network traffic. According to the number of BTSs, obtain the average traffic load of a

single BTS and channel configuration data.

Description about Capacity Planning

How many subscriber can cell support?

We must Know the following points : Traffic volume generated by subscriber and distribution amount of

subscriber and load per user in busy hour. GOS: Grade of Service or Block rate Amount of TCH and signaling CH The available bandwidth and reuse model Channel configuration N.BErlangErlang table represent the relationship among block rate, traffic volume and

number of CH

How Many Subscriber should Cell Support?

• Given: Number of subscribers in area, Traffic load per subscriber, Coverage area, radius

• Total traffic volume traffic per km2 traffic per cell number of TRX needed per BTS

• Allow extra capacity for roamer and busy hour traffic

Capacity Planning

A local network will be constructed. After two years, the number of subscribers may attain 100,000. Provide that the traffic per subscriber is 0.02Erl, 120 BTSs are required, and the call loss rate is 2%.

Case about Capacity Forecast

Useful information• Subscriber quantity: 100,000• Call loss rate: 2%• Traffic model: 0.02Erl• Number of BTSs: 120

Capacity PlanningCase about Capacity Forecast

① Roaming factor (traffic and developing trend): 10%; dynamic factor (burst traffic): 15%

Network capacity: 10×(1+10%+15%)=125000

① In terms of congestion, use 85% to calculate the bearer capability for traffic. Thus, the design capacity of network is: 12.5/(85%)=147100, that is 150000.

② According to the provided traffic model, that is average 0.02Erl traffic, forecast the busy-hour traffic of the whole network: 150000 ×0.02=3000Erl.

③ The average traffic per BTS is: 3000/120=15Erl, average traffic per cell: 15/3=5Erl.

④ Based on 2% call loss rate, query the Erlang-B to find the number of voice channels: 10 channels/every cell

⑤ The number of control channels: 12 channels/every cell, 2TRX/every cell

Contents







Why Indoors

• Indoor coverage become the main competition between operators• Subscribers expect continuous coverage and better quality• Outdoor cell can’t provide sufficient indoor coverage

INDOOR SOLUTION

Good Quality!

Building Penetration Loss

Signal level in building is estimated by using a building penetration loss margin Big differences between rooms with window and without window(10~15 dB)

rear side :-18 ...-30 dB

Pref = 0 dB

Pindoor = -3 ...-15 dB

Pindoor = -7 ...-18 dB

-15 ...-25 dB no coverage

signal level increases with floor number :~1.5 dB/floor (for 1st ..10th floor)

Building Penetration Loss• Signal loss for penetration varies between different building

materials, e.g.: mean value reinforced concrete wall, windows 17 dB concrete wall, no windows 30 dB

concrete wall within building 10 dB

brick wall 9 dBarmed glass 8 dB

wood or plaster wall 6 dBwindow glass 2 dB

In-Building Path Loss• Simple path loss model for in-building environment

– Outdoor loss: Okumura‘s formula Lout = 42,6 + 20 log( f ) + 26 .. 35 log( d )– Wall loss Lwall = f (material; angle)– Indoor loss: linear model

For Pico-Cells Lin = L0 +(loss per meter)*d

building type loss application example

old house 0,7 dB/m (urban l)

commercial type 0,5 dB/m (modern offices)

open room, atrium 0,2 dB/m (museum, train station)

Lout

Lwall

Lin

Indoor Coverage Examples• With Repeater

– Relay outdoor signal into target building– Need donor cell, add coverage but not capacity

• With indoor BTS and distributed antenna– Heavy loss bring by power splitting and cable

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

1:1:1

1:1

4th floor

3rd floor

2nd floor

1st floor

ground floor

Outdoor AntennaGain: 18 dBi

Indoor AntennaGain: 9dBi

Target Indoor Coverage Building

7/8'' Cable Loss: 4dB / 50mCable length : 25m

-50 dBm

4th Floor

3rd Floor

1st Floor

Ground Floor

2nd Floor

Location Area Design• Location update affects all mobiles in network

Location update in idle mode Location update after call completion

• Location update brings extra burden to the network • Good location area design should avoid ping-pong location update• Paging ability is limitation of location area

Location area 1

Location area 2

major road

Paging VS Location update Traffic

PagingLocation update

# of cells in Loc. area

signalingtraffic

optimum numberof cells in Loc. area

function of user density,cell size, call arrival rate ...function of

user mobility

minimize signaling traffic

optimum varies with network evolution

Contents







Interference (C/I) Estimation

1/2

q = D/R = ( 3 k )

6

q

I

C

fnfn

fnfn

fn

fnfn

RD

Interference of six co-channel cell to service cell

D : is the co-channel reuse distanceR : is the radius of the hexagon cellK : is the frequency reuse densityγ : path attenuation slope specified by actual landform environment (Path attenuation value in mobile environment γ=4)

A1C1

B1D1

A2A3

B2B3

C2C3

D2D3

A1C1

B1D1

A2A3

B2B3

C2C3

D2D3

A1C1

B1D1

A2A3

B2B3

C2C3

D2D3 A1

C1

B1D1

A2A3

B2B3

C2C3

D2D3

A1C1

B1D1

A2A3

B2B3

C2C3

D2D3

A1C1

B1D1

A2A3

B2B3

C2C3

D2D3

4*3 Frequency Reuse

Illustration of Frequency Allocation of 4*3 Frequency Reuse

Looser reuse

Higher frequency reuse

efficiency, but interference

is serious. More technique

Is needed.

Tighter reuse

0 10 20

Little interference, but frequency

reuse efficiency is low.

Reuse Density

– Reuse density is the number of cells in a basic reuse cluster.

4*3 ： 12n*m ： n*m

n: BTS number in a basic reuse clusterm: Frequency group number in a BTS

Frequency Planning Principle In the same cell, the frequency interval between channels

should be higher than 400K.

In the same site, the frequency interval between channels

should be higher than 400K.

In the direct adjacent sites, avoid co-channel, even if the

direction of the antenna is different

In the opposite adjacent cells, avoid adjacent channel

Avoid that co-BCCH and co-BSIC appear in adjacent area.

Good network structure is the basis of a good frequency plan.

How to judge the BTS configuration base on the frequency reuse pattern

Example 1

Frequency resource 9.6MHz

Interval 200K

48 channels 4*3 pattern

（ 4×3 ＝ 12）

48/12=4

Available site type

S444

Example 2

• Suppose 900 band: 96 ～ 124• BTS configuration: S3/3/3• BCCH layer: 96 ～ 109 reuse pattern: 4*3• TCH layer: 110 ～ 124 reuse pattern: 1*3

How to allocate 1*3 Frequency Reuse

TCH Consecutive Allocation Scheme

MAIO

MA1 110 111 112 113 114 0,2

MA2 115 116 117 118 119 0,2

MA3 120 121 122 123 124 0,2

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3

TCH Interval Allocation Scheme

MAIO

MA1 110 113 116 119 122 0,2

MA2 111 114 117 120 123 1,3

MA3 112 115 118 121 124 0,2

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3

MA1

MA2 MA3

Cell1

Cell2Cell3

Class of Hopping

Hopping can be implemented in two ways

Base-band hopping

RF hopping

Class according to the min hopping time unit

Timeslot hopping

Frame hopping

Base Band Hopping Principle

RF Hopping Principle

Parameter of hopping• CA (Cell Allocation) ： All frequencies available in the cell • MA （ Mobile Allocation ) ： All frequencies available for FH in the cell • HSN (Hopping sequence number): an array of all frequencies in MA

HSN=0 ： cycle hopping. HSN≠0 ： random hopping. Every sequence number corresponds a

pseudo random sequence.• MAI (Mobile Allocation Index ): the sequence number of frequency• MAIO （ Mobile Allocation Index Offset）： The offset from the initial

point in an array of frequency• TSC （ Training Sequence Code ）： Consistent with the cell BCC and

cannot be edited

Contents







Why

• Handover is based on the neighbor relationship.• Existing problem of neighbor planning

No neighbor relationship, no handover Co-BCCH and co-basic between adjacent cells lead to handover failure. redundant neighbors missing neighbor

Neighbor Cell Description

• There are table BA1 and table BA2.• Table BA1 describes BCCH frequencies of the adjacent cells to be

measured when the MS is in idle mode.• Table BA2 describes BCCH frequencies of the adjacent cells to be

measured when the MS is in dedicated mode.• There are two kinds of neighbors

– bidirectional neighbors– unidirectional neighbors

• Bidirectional neighbors are common, and unidirectional neighbors are used in special condition, such as overshooting

B

C

A

A

• The signals of cell A covers some areas far away from this

cell. It is overshooting.

• When MS moves from this area towards B and C

in dedicated mode, the signal is worse and worse.

• since cell B and C is not the cell A’s neighbor,

call drop will occur finally.

• There are three solution:

• Adjust the downtilt of the antenna

• Adjust the transmitting power of the BTS

• Add B and C as the neighbor of cell A, no need to add

A to B and C, that is unidirectional neighbor.

(make sure that there are no co-BCCH and co-BSIC in neighbor list)

Overshooting and unidirectional neighbor

• The cells of co-site must be set as neighbor cells• The cells confronting directly must be added to neighbor list• The cells facing toward the same direction should be neighbors

The cells shooting by the original cell The cells shooting at the original cell

• The cells, one site apart, face to face should be neighbor cells.

Neighbor Planning Principle

Demonstration (ideally)

co-site cellConfronting cellsame directional cellone site apartface to face cell

Original cell

Thank you

network planning.ppt

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