GSM , RF & DT

Telecom Tutorials
Monday, June 03, 2013www.tempustelcosys.com
RF & GSM Concepts

Basic Telecom concepts
Various Wireless Technologies
Cellular concepts & Principal of cellular Comm.
GSM Network Architecture
GSM channel Architecture
Call Flows in GSM
GSM Planning steps (Nominal Plan & RF surveys)
GSM Optimization Steps ( Performance, Drive testing & Benchmarking)

Till 1982 Cellular Systems were exclusively Analog Radio Technology.
Advanced Mobile Phone Service (AMPS)
U.S. standard on the 800 MHz Band
Total Access Communication System (TACS)
U.K. standard on 900 MHz band
Nordic Mobile Telephone System (NMT)
Scandinavian standard on the 450 & 900 MHz band

GSM - 900
The term GSM-900 is used for any GSM system which operates in any 900 MHz band.
P-GSM - 900
P-GSM-900 band is the primary band for GSM-900 Frequency band for primary GSM-900 (P-GSM-900) : 2 x 25 MHz
890 – 915 MHz for MS to BTS (uplink)
935 – 960 MHz for BTS to MS (downlink)
E-GSM - 900
In some countries, GSM-900 is allowed to operate in part or in all of the following extension band. E-GSM-900 (Extended GSM-900) band includes the primary band (P-
GSM-900) and the extension band :
R-GSM-900
R-GSM-900 (Railway GSM-900) band includes the primary band (P-GSM-900) and the following extension band:
GSM-1800
Frequency band: 2 x 75 MHz
1710 – 1785 MHz for MS to BTs (uplink)

Telecom Service Providers/Operators
GSM
CDMA
Basic-WLL
Internet Services
Long Distance
Vendor
Telecom Consultancy

 End of 1980‟s Analog Systems unable to meet continuing demands
 Severely confined spectrum allocations
 Interference in multipath fading environment
 Incompatibility among various analog systems
 Inability to substantially reduce the cost of mobile terminals and infrastructure required

Spectrum space - most limited and precious resource
Solution - further multiplex traffic (time domain)
Can be realized with Digital Techniques only

 1979 Europe wide frequency band reserved for Cellular
 1982 “Groupe Speciale Mobile” created within CEPT
 1986 GSM had full time in Paris
 1988 ETSI takes over GSM Committee
 1990 The phase 1 GSM Recommendations
frozen
 1991 GSM Committee renamed “Special Mobile Group” and
GSM renamed as “Global System for Mobile Communication”
 1992 GSM launched for commercial
operations

Service Provider is not a Equipment Manufacturer.
The Service Provider has a license to operate in a geographical boundary (state/circle/ country).
It buys equipment from OEM Suppliers (Vendors).
Installs & commissions the equipment thus making it‟s own Network.
Provides the desired service to it‟s subscribers.

Vendor is a Equipment Manufacturer.
It supplies Product, Consultancy and Trainings
Service provider has the option of taking the Consultancy and Training

A cellular system links Mobile subscribers to Public
Telephone System or to another Mobile subscribers.
It removes the fixed wiring used in a traditional telephone installation.
Mobile subscriber is able to move around, perhaps can travel
in a vehicle or on foot & still make & receive call.

Mobility
Flexibility
Convergence
Greater QOS
Network Expansion
Revenue/Profit

CONSIDERATIONS -
 FREQUENCY
 SUBSCRIBER DENSITY
 COVERAGE
14
Base Station
Base Station
Base Station
Base Station
Base Station
Base Station

Cellular Radio involves dividing a large service area into regions called “cells.”
Each cell has the equipment to switch, transmit and receive calls.
Cells - Reduce the need of High powered transmission
Cells - Conventionally regarded as being hexagonal, but in reality they are irregularly shaped.
Cell shape is determined by the nature of the surrounding
area e.g. Hills , tall building etc.

Large Cells
35 Km
Remote Areas
High Transmission Power
Few subscribers
Small Cells
Near about 1 KM
Urban Areas
Low Transmission Power
Many Subscribers

Coverage
Percentage of the geographical area covered by cellular service where mobile telephony is available
Capacity -
Number of calls that can be handled in a certain area within a certain period of time.
Capacity can also refer to the probability that users will be denied access to a system due to the
simple unavailability of radio channels.

Designation Abbreviation Frequencies Free-space Wavelengths
Very Low Frequency VLF 9 kHz - 30 kHz 33 km - 10 km
Low Frequency LF 30 kHz - 300 kHz 10 km - 1 km
Medium Frequency MF 300 kHz - 3 MHz 1 km - 100 m
High Frequency HF 3 MHz - 30 MHz 100 m - 10 m
Very High Frequency VHF 30 MHz - 300 MHz 10 m - 1 m
Ultra High Frequency UHF 300 MHz - 3 GHz 1 m - 100 mm
Super High Frequency SHF 3 GHz - 30 GHz 100 mm - 10 mm
Extremely High Frequency EHF 30 GHz - 300 GHz 10 mm - 1 mm

Each Cell in the Cellular Network consists of one or more RF carriers.
An RF carrier is a pair of radio frequencies
One used in upward direction by MS - Uplink
Other used in downward direction by BTS - Downlink
The transmit and receive frequencies are separated by a gap of 45 MHz in GSM of 75 MHz in DCS.
There are 124 carries in GSM Band. With each carrier carrying 7 timeslots, only
124 x 7 = 868 calls can be made!
Frequency Reuse is the solution

Ful(n) = 890.0 + (0.2) *n MHz
Fdl(n) = Ful + 45 MHz
where n =ARFCN ; 1 n 124

Power
Frequency
Time
FDMA
Frequency
Power Time
TDMA
FrequencyCDMA
Power
Time

Power
TDMA
Power
FDMA
Power
CDMA
FDMA: AMPS & NAMPS
•Each user occupies a private Frequency,
protected from interference through physical
separation from other users on the same
frequency
•TDMA: IS-136, GSM
•Each user occupies a specific frequency but
only during an assigned time slot. The
frequency is used by other users during
other time slots.
•CDMA
•Each user occupies a signal on a particular
frequency simultaneously with many other
users, but is uniquely distinguishable by
correlation with a special code used only by
this user

Three types of frequency reuse
patterns
7 Cell reuse pattern
4 cell reuse pattern
3 cell reuse pattern

c2
c1
c3
a1
a2
a3
b1
b2
b3
c1
c2
c3
Cell Re-use

Frequency Re-use
Cell Dia = R
7/21 cell cluster
1
2
3
4
5
6
7
D D=R (3N)
where N is Cluster size

Omni Directional Cells
120 degree Sectors
60 Degree sectors
Each Sector in a Site has its own allocation of Radio Carriers
Advantage
By frequent reuse of frequency more capacity can be achieved

 Multipath Fading results in variations in signal strength which is known as Raleigh
Fading.
 Raleigh Fading phenomenon is dependent on path difference and hence
frequency of reception.
 A fast moving mobile may not experience severe effect of this fading since the
path difference is continuously changing.
 A slow moving mobile ( or a halted mobile ) may experience severe deterioration in
quality.
 But, if the frequency of reception is changed when this problem occurs ,could
solve it.
 The fading phenomenon is fast and almost continuos, this means the frequency
change should also be continuos.
 This process of continuously changing frequency is known as Frequency Hopping.

Reduction in Average Interference
 With Frequency Hopping consistent interference will become bursty.
 So even though, both the co-channel cells will be using the same set of ARFCN's for Hopping,
interference will not be continuos.
 This is because, GSM cells are not Frame synchronized, and change in frequency is related to Frame
nos.
 If same HSN is used in two cells, then either the interference will be nil , or if a phase correlation exists
then it will be continuos.
 So the two cells should preferably use different HSN's .
 Sectorial cells ( controlled by the same BTS) can use same HSN, since the sectors don't come up at the
same time.
 Cells if they are synchronized, can use same HSN, if each cell has an offset of some TDMA frames.
 Offset of TDMA frames is also required to avoid SACCH occurring at the same time in all synchronized
cells, as they kills away the objective of DTX.

a1
a2
a3a3
a4a6
a5
OMNI CELL
1 ANTENNA
b1
b2
b3
120O CELLS
3 ANTENNAS
60O CELLS
6 ANTENNAS

 Compatibility
 Noise Robust
 Increased Capacity & Flexibility
 Use of Standard Open Interfaces
 Improved Security & Confidentiality
 Cleaner Handovers
 Subscriber Identification
 ISDN Compatibility
 Enhanced Range of Services

Hard Handoff
Analog, TDMA and GSM
Soft Handoff
CDMA
Break before Make Make before Break

120
181
198
200
132
41
44
24
69
75
113
28
71
73
70
80
7
8
11
12
13 16
17
18
19
20
22
25
32
40
171
173
175
182
187
197
199
201
213
214
215
216
218
219
220
221
222
225

The mobile measures up to 32 adjacent cells for
Signal Strength (RxLevel)
Signal Quality (RxQual)
updated every 480 mS and sends to BTS
Sophisticated Handover based on
RxLevel
Interference
RxQual
Timing Advance
Power Budget

BT
S
BT
S
BT
S
BT
S
BT
S
BT
S
BT
S
BT
S
BSC
VL
R
HL
R EI
R
OM
C
SMS
C
B
C
AU
C
VMS
C
MS
C
A
MS
BTS
BTS
BTS
BTS BTS
BTS
BTS
BTS
BSC
BSC
PSTN
VLR
TRAU
HLR
EIR
OMC
SMSC
BC
AUC
VMSC
MSC
A
OML

MSISDN : Human Identity used to call a Mobile Station
IMEI: Serial number unique to every Mobile Station
IMSI : Network Identity unique to a SIM
3 digits 2 digits 10
digits TMSI : Identity unique in a LAI
MSRN : Mobile Station Roaming No
CC NDC SN
98 XXX 12345
MCC MNC MSIN
404 XX 12345
TAC FAC SNR S
6 digits 2 digits 6 digits 1 digit

Mobile Station consists of two parts-
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
ME
Hardware e.g. Telephone, Fax Machine, Computer.
SIM
Smart Card which plugs into the ME.

 Revision Level
 Phase of the GSM specs ME comply with.
 RF Power Capability
 Max power ME is able to Transmit.
 Ciphering Algorithm Used
 Presently A5
 Phase 2 specifies Algorithms A5/0 to A5/7.
 Frequency Capability
 SMS Capability

Class Power
O/p
1 20 W
2 8 W
3 5 W
4 2 W
5 0.8 W
Typical
Settings

IMSI(International Mobile Subscriber Identity)
Transmitted over Air Interface on initialization
Permanently stored on SIM card
15 digit Decimal

 MSISDN
 10 digit number to which a subscriber is being called.
 PIN (Personal Identification Number)
 Four digit PIN
 An internal security to Protect the SIM from illegal use.
 Card blocks itself after three wrong entries
 PUK (Personal Unblocking Key)
 8 digit code to unblock the SIM Card
 Ki (Authentication Key), A3 & A8 Algorithms

 Temporary Mobile Subscriber Identity
 Periodically changed by the System Management on instances like location update etc.
 Reason for use of TMSI
 To prevent a possible intruder from identifying GSM users, TMSI is used
 Management
 Assignment, Administration & Updating is performed by VLR.

Converts 64 Kbps PCM circuits from MSC to 16 Kbps BSS circuits.
Each 30 channel 2 Mbps PCM link can carry 120 GSM - specified voice
channels.

BSS (Base Station
System)
BSC (Base Site Controller)
BTS (Base Transceiver
Station)
XCDR (Transcoder)
Network
Switching
System
(NSS)
XCDR
BSC
BTS

BSC
Controls upto 40 BTS
Conveys information to/from BTS
Connects terrestrial circuits & Air Interface Channels
Controls handovers between BTSs under itself
BTS
Contains RF Hardware
Limited control functionality
1 - 6 carriers in a BTS Cabinet
7 - 48 simultaneous calls per BTS

Collocated BTS
Remote BTS
Star Configuration
Daisy Chain BTS
BSC
BTS
BTS
BTS
AllBTSon1E1
BSC
BTS
B
T
S
BTS
BTS

NSS (Network Switching System)
MSC (Mobile Switching Centre)
HLR (Home Location Register)
VLR (Visitor Location Register)
EIR (Equipment Identity Register)
AUC (Authentication Centre)
IWF (Interworking Function)
EC (Echo Canceller)

MSC
Call Switching
Operation & Management Support
Internetwork Interworking
Collects call billing data
Gateway MSC
MSC which provides interface between PSTN & BSS‟s in the GSM Network.

Reference database for the Subscriber profiles-
Subscriber ID (IMSI & MSISDN)
Current VLR Address
Supplementary Services subscribed
Supplementary Service Information
Subscriber Status (Registered/deregistered)
Authentication Key and AUC functionality
TMSI
MSRN

Temporary Data, which exists as long as the subscriber is
active in a particular Coverage area.
Contains the following-
Mobile Status (Busy/ Free/ No Answer/etc.)
Location Area Identity (LAI)
TMSI
MSRN (Mobile Station Roaming Number)

Contains Database for validating IMEI
White List (valid ME)
Black List (Stolen ME)
Grey List (Faulty ME)

Provides function to enable the GSM System to interface with Public/Private Data Networks.
The basic feature of the IWF are
Rate Conversion
Protocol adaptation
IWF incorporates Modem Bank.
e.g. GSM DTE PSTN DTE
IWF Analogue Modem

 Echo is apparent only in Mobile - Land conversation & is generated
at the 2 wire to 4 wire interface.
 To avoid it, Echo Canceller (EC) is used.
 Echo is irritating to MS Subscriber
 Total Round Trip delay of 180 ms in the GSM system
 EC is placed on the PSTN side of the Switch
 Cancellation up to 68 ms with EC

Event & Alarm Management
Fault Management
Performance Management
Configuration Management
Security Management

Broadly classified into two types of interfaces-
Standard Interfaces
2 Mbps Trunks (E1)
Signalling System No. 7 SS7 ( CCS7)
X.25 (Packet Switched Mode)
GSM Interfaces

Um MS - BTS
Abis BTS - BSC
A BSC - MSC
B MSC - VLR
C MSC - HLR
D VLR - HLR
E MSC - MSC
F MSC - EIR
G VLR - VLR
H HLR - AUC

GSM protocols are basically divided into three layers:
Layer 1: Physical layer
Enables physical transmission (TDMA, FDMA, etc.)
Assessment of channel quality
Except on the air interface (GSM Rec. 04.04), PCM 30 or ISDN
links are used (GSM Rec. 08.54 on Abis interface and 08.04 on
A to F interfaces).
Layer 2: Data link layer
Multiplexing of one or more layer 2 connections
on control/signaling channels
Error detection (based on HDLC)
Flow control
Transmission quality assurance
Routing
Layer 3: Network layer
Connection management (air interface)
Management of location data
Subscriber identification
Management of added services (SMS, call forwarding, conference
calls, etc.)

AUTHENTICATION
CIPHERING
REGISTRATION
CALL ESTABLISHMENT
HANDOVER / HANDOFF
ROAMING

NSS
MS
HLR
AUC
AUTH.
ALGORITHMS
A3
SIM
MS
AUTH.
ALGORITHMS
A3
Ki
RAND
RAND
COMPARE
SRES
SRES
Ki
AIR INTERFACE

Data protection is required on
air interface.
A specific key called Ciphering
Key (Kc), is generated from
RAND and A8 algorithm.
A8 is on the SIM.
A8
RANDKi
Kc

A5Data
Kc
Ciphered
Data
A5
Kc
Data

Access Network
Microwave 15 /23 GHz
Backbone Network
Microwave 7 GHz
Optical Fibers
Leased Line( From Dot or any other service provider on any media)

Different Possible Combinations
Mono Mode Step Index 10 / 125 m
Mono Mode Graded index
Multi Mode Step Index 100 / 300 m
Multi Mode Graded Index 75 / 130 m
Mono Mode Graded Index would have been the best but fabrication not possible
140 Mbps OLTE , Mono Mode Step Index in our case

Physical Channel
Logical Channel
Physical Channel
Physical channel is the medium over which the information is carried.
Logical Channel
Logical channels consists of the information carried over the Physical Channel.

0 1 2 3 4 5 6 7
3
57
encrypted
57
encrypted
26
training
1
S
1
S
3
T
8.25
GP
3
T
577 S
577 S x 8 = 4.615mS
TDMA Frame
Normal Burst
26 Frame Multi-frame

 Time is divided into discrete periods called
“Timeslots”
• TCH carries payload data - speech, fax, data
• Connection may be:
- Circuit Switched - voice or data or
- Packet Switched – data
• TCH may be:
• Full Rate (TCH/F)
- one channel per user
- 13 kb/s voice, 9.6 kb/s data or
• Half Rate (TCH/H)
- one channel shared between two users
- 6.5 kb/s voice, 4.8 kb/s data
Traffic Channels
TCH/F
Full rate 22.8kbits/s
TCH/H
Half rate 11.4 kbits/s

DCCH(Dedicated Channels)
Downlink & Uplink
CCCH(Common Control Chan)
Downlink & Uplink
Synch.
Channels
RACH
Random
Access Channel
CBCH
Cell Broadcast
Channel
SDCCH
Standalone
dedicated
control channel
ACCH
Associated
Control Channels
SACCH
Slow associated
Control Channel
FACCH
Fast Associated
Control Channel
PCH/
AGCH
Paging/Access grant
FCCH
Frequency
Correction channel
Control Channels
BCH ( Broadcast channels )
Downlink only
BCCH
Broadcast
control channel
SCH
Synchronization
channel

BCH channels are all downlink and are allocated to timeslot zero.
Channels are:
• FCCH: Frequency control channel sends the mobile a burst of all „0‟
bits which allows it to fine tune to the downlink frequency
• SCH: Synchronization channel sends the absolute value of the frame number (FN), which is the
internal clock of the BTS, together with the Base Station Identity Code (BSIC)
• BCCH: Broadcast Control Channel sends radio resource
management and control messages, Location Area Code and so on.
Some messages go to all mobiles, others just to those that are in the
idle state

•CCCH contains all point to multi-point downlink channels (BTS to
several MSs) and the uplink Random Access Channel:
• CBCH: Cell Broadcast Channel is an optional channel for general
information such as road traffic reports sent in the form of SMS
• PCH: Paging Channel sends paging signal to inform mobile of a call
• RACH: Random Access Channel is sent by the MS to request a
channel from the BTS or accept a handover to another BTS.
A channel request is sent in response to a PCH message.
• AGCH: Access Grant Channel allocates a dedicated channel
(SDCCH) to the mobile
• NCH: Notification Channel informs MS about incoming group or
broadcast calls

SDCCH( Standalone Dedicated Control Channel )
Uplink and Downlink
Used for call setup, location update and SMS.
SACCH( Slow Associated Control Channel )
Used on Uplink and Downlink only in dedicated mode.
Uplink SACCH messages - Measurement reports.
Downlink SACCH messages - control info.
FACCH( Fast Associated Control Channel )
Uplink and Downlink.
Associated with TCH only.

The Time Slots are arranged in a sequence , conventionally numbered 0 to 7.
Each repetition of this sequence is called a TDMA Frame.
The information content carried in one time slot is called a “burst”.

 Information
 Main Area where the Speech, Data or Control info is held
 Guard Period
 To enable the burst to hit the time slot (0.031ms)
 Stealing Flags
 2 bits are set when TCH is to stolen by a FACCH
 Training Sequence
 For estimation of transfer characteristics of physical media
 Tail Bits
 Used to indicate beginning and end of the burst.

0 1 2 3 4 5 6 7 2 4 5 6 730 1
FRAME 1 FRAME 2
Training SequenceInformation Information
GUARD
PERIOD
GUARD
PERIOD
TAIL BITS TAIL BITS

 Normal Burst
Traffic & Control Channels Bi-directional
 Frequency Correction Burst
FCCH Downlink
 Synchronization Burst
SCH Downlink
 Dummy Burst
BCCH Carrier Downlink
 Access Burst
RACH Uplink

Mobile to Mobile
Intra-city
Inter-city
Mobile to Land
Intra-city
Inter-city
Land to Mobile
Intra-city
Inter-city

1
3
CHANNEL REQUEST
DCCH ASSIGN
SIGNALLING LINK
ESTABLISHED
REQUEST FOR SERVICE
SET CIPHER MODE
SET-UP
EQUIPMENT ID
REQUEST
AUTHENTICATION
MS BSS MSC VLR HLR PSTNEIR
RACH
AGCH
SDCCH
SDCCH
Call
Info7
4
6
5
2
CR
CC

8
COMPLELTE CALL
CALL PROCEEDING
9 ASSIGNMENT COMMAND
INITIAL & FINAL
ADDRESS (IFAM)
ASSIGNMENT COMPLETE
(ACM)
10
ANSWER(ANS)
11
CONNECT ACKNOWLEDGE
SDCCH
SDCCH
ASSIGNMENT COMPLELTE
MS HEARS RINGTONE
FROM LAND PHONE
ALTERING
RING TONE
STOPS
CONNECT
(channel)
(TCH)
FACCH
FACCH
FACCH
TCH
(circuit)
FAACH
BILLING STARTS
Hello!
MS BSS MS
C
VLR HLR PSTN EIR

• Calling Line Identification
– Present
– Absent
• Connect Line Identification
– Present
– Absent
• Closed User Group - CUG
– Only incoming
– Only outgoing
• Operator Controlled Barring

Data rates supported as of today are
 2.4 Kbps
 4.8 Kbps
 9.6 Kbps
 GPRS & EDGE implementation takes the data capability to higher level of the order of 184
kbps and more

• Good coverage – where ever he goes
• Good quality
• No blocking
• Value added services
– SMS
– Voice mail
– MMS
– Call forward/call waiting
– Data/internet at high data rates
– prepaid

The basic objectives of a wireless system are:
– COVERAGE: provide sufficient cell sites to deliver RF coverage of the entire desired area.
– BUILDING/VEHICLE PENETRATION: deliver sufficient signal levels to adequately penetrate
buildings and vehicles where appropriate.
– TRAFFIC: ensure that no cell captures more traffic than it can handle at the desired grade of
service (i.e., blocking percentage)
– PERFORMANCE: design, construct, and adjust the network to deliver reliable service free
from excessive origination and call delivery failures, dropped calls, quality impairments, and
service outages.
– ECONOMICS: provide return on investment sufficient to support operating and capital
expenses, expand the network to take advantage of growth opportunities, and retire costs of
construction prior to depreciation of the network equipment

Inputs
– Coverage objectives
• Area coverage objectives
• Coverage penetration objectives
– Morphology data/clutter information
– Terrain data and Vector maps
– Traffic objectives
• Number of subscribers defined
• Traffic per subscriber defined
• Desired grade of service defined
– City regulations
– BTS Hardware specifications
– Link Budget
– Business and Logistical objectives
• Capital budget
• Timing: launch data
• Operating revenue Vs. total costs
• Output
– Cell database and traffic model
– Composite coverage plot
– Equal power handoff boundaries plot

• Site acquisition
– Availability of suitable candidate (building or land)
– Owner interest
– Cost of leasing
– Frequency clearance (SACFA)
– Government authority approval
– Space constraints and other construction issues
• Candidate Location – line of sight to the objective
• Clutter type
• Terrain variations
• Physical Blocking – buildings, hoardings
• Water
• Mumbai – High end, high traffic areas are very close to water….
Makes RF design much more challenging
• Deviation from desired location impacts surrounding site locations

• Understand geographical area as per license agreement
• Define coverage expectations in terms
– On road coverage
– In-building coverage (different penetration margins)
• Capacity considerations – busy hour per subscriber call attempts and minutes of use
(Erlangs)
• 1 Erlang is 1 call of 1 hour duration
• Decide number of sites based on coverage capacity requirement
• Propagation tools used for this analysis
• Finalize exact site locations after field survey
• Initiate candidate identification process
• Site acquisition/antenna positioning
• Modify existing design if site location changes

Traffic &
Growth
Analysis
System
Optimisation
Site Coverage
Confirmation
Site Search &
Selection
Propagation
model
verification
System/Site
Dimensioning
RF &Network
Planning
Market
Requirement
Site Acquisition
Site Build
Operational
Network
Site Search
Plan
Performance
Monitoring

 Various steps are listed below
 CW survey
 Model Tuning
 Nominal Planning
 RF site Surveys
 Realized Planning
 Frequency Planning
 Implementation
 Optimization
 Drive Testing
 Performance Analysis

It consists of planning a set of sites on planning tool so as to predict the coverage of the target area
Tool needs to be made intelligent so as to predict the coverage as close as possible to actual coverage
Coverage plots are based on customer intension of providing indoor and outdoor coverage

Colaba
Malabar Hill
Mazgaon
>=30dB:: 3-4 wall coverage
25-30dB : 3 Wall Coverage
23-25 dB : 2-3 Wall Coverage
18-23dB: 2-3 Wall Coverage
16-18 dB : 2 Wall Coverage
8-16dB : 1-2wall Coverage
08 dB : On Road-1 Wall Coverage
00 dB : On Road/No Coverage
Indoor Coverage:
Penetration Margin Legend

• Propagation models are used to predict
coverage from a particular site
• A composite coverage plot shows the
overall coverage produced by each sector
in the field of view
• The color of each pixel corresponds to the
signal level of the strongest server at that
point
• Such plots are useful for identifying
coverage holes and overall coverage
extent

Clutter types
Dense Urban
Urban
Sub Urban
Rural
Water
Vegetation
Industrial
Forest

Each nominal has a search ring defined by the RF Planner
Candidates needs to be identified as close as possible to the nominal within the search ring
Height, orientations & antenna placement at site are the key RF parameter which are based upon the
coverage requirement in the area
Major obstructions and clutter type in various directions to be observed on RF survey

Equipment required for RF Survey
GPS
Digital Camera
Binoculars
Magnetic Compass
There might be 3 or more candidates surveys for one site
Each candidate would have an RF survey form and panoramic
associated with it

•Drive testing is an important activity to get statistics & graphs on coverage, quality &
capacity in the downlink direction
• Drive test setup – DT tool, Engineering Handset, GPS,
accessories
• Call in 2 modes
• Dedicated – while the mobile is on call
• Idle – while the mobile is idle
Important parameters observed during drive testing
• Coverage – Rx level (Full & Sub)
• Quality – RxQual & SQI
• Handover, Dropped call, Neighbor list, TA

• Parameters of propagation
models must be adjusted for best
fit to actual drive-test measured
data in the area where the model
is applied
• The figure at right shows drive-
test signal strengths obtained
using a test transmitter at an
actual test site
• Tools automate the process of
comparing the measured data
with its own predictions, and
deriving error statistics
• Prediction model parameters
then can be “tuned” to minimize
observed error

• The words “performance optimization” mean different things to different people, viewed
from the perspective of their own jobs
• System Performance Optimization includes many different smaller processes at many
points during a system’s life
– recognizing and resolving system-design-related issues (can’t build a crucial site, too
much overlap/soft handoff, coverage holes, etc.)
– “cluster testing” and “cell integration” to ensure that new base station hardware works
and that call processing is normal
– “fine-tuning” system parameters to wring out the best possible call performance
– identifying causes of specific problems and customer complaints, and fixing them
– carefully watching system traffic growth and the problems it causes - implementing
short-term fixes to ease “hot spots”, and recognizing problems before they become
critical

Optimisation is an ongoing process of analysing network performance
against Quality of Service targets:

•Measurements of network performance cover:
• Traffic in erlangs
• TCH and SDCCH Grade of Service (Congestion)
• Call success rate
• Handover failure
• Coverage area
• Coverage quality
• Subscriber base and growth
• Key Performance Indicators (KPI) are measurable dynamic
parameters that help to target areas of concern

Appropriate KPIs to use depend on:
• The nature of the network
• Data sources available
• Measurement tools available
• Ability of engineering team
• Cost of network infrastructure
• Sources of data include:
• Surveyed data - from drive tests
• Network statistics - from OMC
• Field engineer reports

Transmission Timing
Power Control
VAD Voice Activity Detector and DTX
Multipath Fading
Equalization
Diversity
Frequency Hopping
Antenna Parameters ( Height, Azimuth, Tilts )

•Surveyed data from test-mobile measurements can be used to
benchmark system performance against that of a competitor
• Problems that may be identified from surveyed data:
• Poor coverage
• Unexpected interference
• Missing handover definitions
• Installation problems at BTS
• Test-mobile measurements should include:
• continuous calls to test coverage
• repetitive short calls to test call-success

RF Planning Tool
Drive Test Tool
Optimization Tool
MapInfo

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