6949178 gsm fundamentals rf
TRANSCRIPT
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GSM Fundamentals & RF
GTL welcomes you to the Basiccourse on GSM Fundamentals &
RF(GTL-GSM RF-001)
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What you will learn here? 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)
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BASIC Telephony
Off Hook
Dial Tone
Dialing Digits
RBT
Conversation
Ring
Off Hook &
Conversation
SignalingTraffic
SWITCH / EXCHANGE
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Wireless Communication
Alternative means of wireless communication
Walkie - Talkie
Pagers
Trunked private radios
Mobile Phone - the magic technology that enables
everyone to communicate anywhere with anybody.
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Wireless Telephony
BSCBTS BTS
Mobile Subscriber...
MSC
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Different Standards Worldwide
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
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Different Standards Worldwide
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GSM - 900GSM - 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) andthe extension band :
880 890 MHz for MS to BTS (uplink)
925 935 MHz for BTS to MS (downlink)
R-GSM-900R-GSM-900
R-GSM-900 (Railway GSM-900) band includes the primary band (P-GSM-900) and the following extension
band:
876 890 MHz for MS to BTS (uplink)
921 935 MHz for BTS to MS (downlink)
GSM-1800GSM-1800
Frequency band: 2 x 75 MHz
1710 1785 MHz for MS to BTs (uplink)
1805 1880 MHz for BTS to MS (downlink)
Different Standards Worldwide
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Industry Vs Technology Spread
Telecom Service Providers/Operators
GSM
CDMA
Basic-WLL
Internet Services
Long Distance
Vendor
Telecom Consultancy
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Analog Mobile Telephony
End of 1980s 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
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Digital Mobile Telephony
Spectrum space - most limited and precious resource
Solution - further multiplex traffic (time domain)
Can be realized with Digital Techniques only
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GSM History and Organization
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
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Service Industry 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 its own
Network.
Provides the desired service to its subscribers.
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Vendor
Vendor is a Equipment Manufacturer.
It supplies Product, Consultancy and Trainings
Service provider has the option of taking the Consultancy
and Training
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Cellular Communication 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.
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Advantage of Cellular
Communication Mobility
Flexibility
Convergence
Greater QOS
Network Expansion
Revenue/Profit
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WHATIS CELLULAR TELEPHONY ?
CONSIDERATIONS -
TFREQUENCY
TSUBSCRIBER
DENSITY
TCOVERAGE
Base Station
Base Station
Base Station
Base StationBase Station
Base Station
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The Cell Cellular Radio involves dividing a large service area into region
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 reali
they are irregularly shaped.
Cell shape is determined by the nature of the surrounding
area e.g. Hills , tall building etc.
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Cell Size
Large Cells
35 Km
Remote Areas
High TransmissionPower
Few subscribers
Small Cells
Near about 1 KM
Urban Areas
Low TransmissionPower
Many Subscribers
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Coverage & Capacity
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.
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Frequency Spectrum
Designation Abbrevia tion Frequencies F ree-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 mHigh 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
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GSM - IN CELLULAR
TELEPHONY 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 agap of 45 MHz in GSM of 75 MHz in DCS.
There are 124 carries in GSM Band. With each carriercarrying 7 timeslots, only 124 x 7 = 868 calls can be made!
Frequency Reuse is the solution
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Frequency & ARFCN
ul=
89
0to
915
MH
z
dl=
935
to96 0
MH
z
Ful(n) = 890.0 + (0.2) *n MHz
Fdl(n) = Ful + 45 MHz
where n =ARFCN ; 1 n 124
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Power
Frequency
Time
FDMA
Frequency
Power Time
TDMA
FrequencyCDMA
Power
Time
Multiple Access
Methods
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Frequ
ency
Time
Power
TDMA
Frequ
ency
Time
Power
FDMA
Frequ
ency
Time
Power
CDMA
CODE
FDMA: AMPS & NAMPS
Each user occupies a private Frequency,protected from interference through physicalseparation from other users on the samefrequency
TDMA: IS-136, GSM
Each user occupies a specific frequency butonly during an assigned time slot. Thefrequency is used by other users duringother time slots.
CDMAEach user occupies a signal on a particularfrequency simultaneously with many otherusers, but is uniquely distinguishable bycorrelation with a special code used only bythis user
Multiple Access Methods
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Frequency Reuse Pattern
Three types of frequency reuse patterns
7 Cell reuse pattern
4 cell reuse pattern
3 cell reuse pattern
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3 Site Reuse Patternc2
c1
c3
a1
a2
a3
b1
b2
b3
c1c2
c3
Cell Re-use
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Cell Dia = R
FREQUENCY RE - USE
Frequency Re-use
7/21 cell cluster
1
2
3
4
5
6
7
D D=R (3N)where N is Cluster size
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Principal Of Sectorization
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
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5 Multipath Fading results in variations in signal strength which is known as
Rayleigh Fading.
5 Rayleigh Fading phenomenon is dependent on path difference and hence
frequency of reception.
5
A fast moving mobile may not experience severe effect of this fading sincethe path difference is continuously changing.
5A slow moving mobile ( or a halted mobile ) may experience severe
deterioration in quality.
5 But, if the frequency of reception is changed when this problem occurs,
could solve it.5 The fading phenomenon is fast and almost continuos, this means the
frequency change should also be continuos.
5 This process of continuously changing frequency is known as Frequency
Hopping.
FrequencyHopping
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5 Frequency Hopping is done in both Uplink and Downlink .
5 Frequency is changed in every TDMA Frame
5 Mobile can Hop on maximum 64 frequencies
5 The sequence of Hopping can be Cyclic or Non-Cyclic
5 There are 63 Non-Cyclic Hopping sequences possible
5 Different Hopping sequence can be used in the same cell.
5 BCH Timeslot can never HOP, but the remaining Timeslots can
very well hop.
FrequencyHopping
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Reduction in Average Interference
5 With Frequency Hopping consistent interference will become bursty.
5 So even though, both the co-channel cells will be using the same set of ARFCN's for
Hopping, interference will not be continuos.
5 This is because, GSM cells are not Frame synchronized, and change in frequency isrelated to Frame nos.
5 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.
5 So the two cells should preferably use different HSN's .
5 Sectorial cells ( controlled by the same BTS) can use same HSN, since the sectors don't
come up at the same time.5 Cells if they are synchronized, can use same HSN, if each cell has an offset of some
TDMA frames.
5 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.
FrequencyHopping
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a1
a2
a3a3
a4a6
a5
Cell Sectorisation
OMNI CELL
1 ANTENNA
b1
b2
b3
120O CELLS
3 ANTENNAS
60O CELLS
6 ANTENNAS
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Features of GSM Compatibility
Noise Robust
Increased Capacity & Flexibility
Use of Standard Open Interfaces
Improved Security & Confidentiality
Cleaner Handovers
Subscriber Identification
ISDN Compatibility
Enhanced Range of Services
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Handovers
Hard Handoff
Analog, TDMA and GSM
Soft Handoff
CDMA
Break before Make Make before Break
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120
181
198
200
132
41
44
69
75
113
28
71
73
70
80
7
8
1112
13 1617
18
19
20
22
25
32
171
173
175
182
187
199
201
213
214
215
216
218
219
220
221
222
225
Handovers
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Cleaner Handovers 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
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BT
S
BT
S
BT
S
BT
S
BT
S
BTS
BT
S
BT
S
BSC
VL
R
HL
R EI
R
OM
C
SMS
CBC
AU
C
VMSC
MS
C
Abi
s
A
MS
BTS
BTS
BTS
BTSBTS
BTS
BTS
BTS
BSC
BSC
PSTN
VLR
TRAUHLR
EIR
OMC
SMSC
BC
AUC
VMSC
MSC
Abi
s
A
OML
GSM NETWORK ELEMENTS
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Mobile Station Identities
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 NoCC NDC SN
98 XXX 12345
MCC MNC MSIN
404 XX 12345
TAC FAC SNR S
6 digits 2 digits 6 digits 1 digit
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GSM Network Components
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.
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ME (Classmark Information)
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
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Typical
Settings
Mobile Equipment
Class Power O/p
1 20 W
2 8 W
3 5 W
4 2 W
5 0.8 W
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SIM(IMSI)
IMSI(International Mobile Subscriber
Identity)
Transmitted over Air Interface on initialization
Permanently stored on SIM card
15 digit Decimal
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SIM (TMSI)
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.
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Transcoder
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.
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Base Station System (BSS)
BSS (Base Station System)
BSC (Base Site Controller)
BTS (Base Transceiver Station)
XCDR (Transcoder)
Network
Switching
System
(NSS)XCDR
BSC
BTS
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Base Station System (BSS)
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
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BSS Configuration
Collocated BTS
Remote BTS
Star Configuration
Daisy Chain BTS Loop ConfigurationBSC
BTS
BTS
BTS
AllBTS
on1E1
BSC
BTS
B
TS
BTS
BTS
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Network Switching System(NSS)
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)
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GSM Network Component
MSC
Call Switching
Operation & Management Support Internetwork Interworking
Collects call billing data
Gateway MSC MSC which provides interface between PSTN & BSSs
in the GSM Network.
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Home Location Register (HLR)
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
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Visitor Location Register (VLR)
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)
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Equipment Identity Register (EIR)
Contains Database for validating IMEI
White List (valid ME)
Black List (Stolen ME)
Grey List (Faulty ME)
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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
Inter Working Function
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Echo Canceller
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
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Operation & Maintenance Centre
Event & Alarm Management
Fault Management
Performance Management
Configuration Management
Security Management
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GSM Terrestrial Interfaces
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
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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
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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 30or ISDN
links are used (GSM Rec. 08.54 on Abis interface and08.04 onA to F interfaces).
Layer 2: Data link layer Multiplexing of one or more layer 2 connectionson 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,
conferencecalls etc.
GSM Protocol Layers
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Basic Processes
AUTHENTICATION
CIPHERING
REGISTRATION
CALL ESTABLISHMENT
HANDOVER / HANDOFF
ROAMING
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AUTHENTICATION ALGORITHM
NSS
MS
HLR
AUC
AUTH.ALGORITHMS
A3
SIM
MS
AUTH.ALGORITHMS
A3
Ki
RAND
RAND
COMPARE
SRES
SRES
Ki
AIR INTERFACE
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Ciphering 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
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Ciphering
A5Data
Kc
Ciphered
Data A5
Kc
Data
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Transmission Media
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)
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Optical Fiber
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 bestbut fabrication not possible
140 Mbps OLTE , Mono Mode Step Index in our case
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Channels On Air Interface
Physical Channel
Logical Channel
Physical Channel
Physical channel is the medium over which theinformation is carried.
Logical Channel
Logical channels consists of the information carried overthe Physical Channel.
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LOGICAL CHANNELS
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
577S
577S x 8 = 4.615mS
TDMA Frame
Normal Burst
26 Frame Multi-frame
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GSM Channels
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Traffic Channel
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
Traffic Channels
TCH/FFull rate 22.8kbits/s
TCH/HHalf rate 11.4 kbits/s
Time is divided into discrete
periods called Timeslots
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Control Channel
DCCH(Dedicated Channels)Downlink & Uplink
CCCH(Common Control Chan)Downlink & Uplink
Synch.Channels
RACHRandom
Access Channel
CBCHCell Broadcast
Channel
SDCCHStandalonededicated
control channel
ACCHAssociated
Control Channels
SACCHSlow associatedControl Channel
FACCHFast AssociatedControl Channel
PCH/AGCH
Paging/Access grant
FCCHFrequency
Correction channel
Control Channels
BCH ( Broadcast channels )Downlink only
BCCHBroadcast
control channel
SCHSynchronization
channel
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Common Control Channels (CCCH)
CCCH contains all point to multi-point downlinkchannels (BTS to
several MSs) and the uplinkRandom 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
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Dedicated Control Channels (DCCH)
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.
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BURST
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 iscalled a burst.
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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.
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GSM Burst & TDMA Frame
0 1 2 3 4 5 6 7 2 4 5 6 730 1
FRAME 1 FRAME 2
Training Sequencenformation InformationGUARD
PERIODGUARD
PERIOD
TAIL BITS TAIL BITS
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Five Types of Burst 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
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Call Scenarios
Mobile to Mobile
Intra-city
Inter-city Mobile to Land
Intra-city
Inter-city
Land to Mobile
Intra-city
Inter-city
M bil T L d S
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Mobile To Land Sequence
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
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8
COMPLELTE CALL
CALL PROCEEDING
9 ASSIGNMENT COMMAND
INITIAL & FINALADDRESS (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
Call Contt.
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Supplementary Services Calling Line Identification
Present
Absent
Connect Line Identification Present
Absent
Closed User Group - CUG
Only incoming
Only outgoing
Operator Controlled Barring
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Data Services
Data rates supported as of today areData rates supported as of today are
2.4 Kbps2.4 Kbps
4.8 Kbps4.8 Kbps
9.6 Kbps9.6 Kbps
GPRS & EDGE implementation takes the dataGPRS & EDGE implementation takes the data
capability to higher level of the order of 184capability to higher level of the order of 184
kbps and morekbps and more
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Customer..Expectation
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
Basic Network Design
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Basic Network DesignObjectives
The basic objectives of a wireless system are:
COVERAGE: provide sufficient cell sites to deliver RF coverage ofthe entire desired area.
BUILDING/VEHICLE PENETRATION: deliver sufficient signal levelsto 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 todeliver reliable service free from excessive origination and calldelivery failures, dropped calls, quality impairments, and service
outages. ECONOMICS: provide return on investment sufficient to support
operating and capital expenses, expand the network to takeadvantage of growth opportunities, and retire costs ofconstruction prior to depreciation of the network equipment.
High Level Design
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High Level Design
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
Background Issues Impacting
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Background Issues ImpactingSystem Design
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 towater.
Makes RF design much more challenging
Deviation from desired location impacts surrounding
site locations
D i id ti f N t k
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Design considerations of Network(GSM/CDMA)
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 andminutes 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
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Traffic &
Growth
Analysis
System
Optimisation
Site Coverage
Confirmation
Site Search &
Selection
Propagationmodel
verification
System/SiteDimensioning
RF &Network
Planning
Market
Requirement
Site Acquisition
Site Build
Operational
Network
Site Search
Plan
PerformanceMonitoring
Flow Chart for Network Deployment
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GSM Planning Steps Various steps are listed below
CW survey
Model Tuning
Nominal Planning
RF site Surveys
Realized Planning
Frequency Planning
Implementation
Optimization Drive Testing
Performance Analysis
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Nominal Planning
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 predictthe coverage as close as possible to actual
coverage
Coverage plots are based on customer intension of
providing indoor and outdoor coverage
Mumbai Coverage
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Mumbai CoverageExpectation Boundary
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Coverage Maps Reverse Link.
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
Composite Coverage
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Composite CoveragePlot
Propagation models are used topredict coverage from a particularsite
A composite coverage plot shows theoverall coverage produced by eachsector in the field of view
The color of each pixel corresponds
to the signal level of the strongestserver at that point
Such plots are useful for identifyingcoverage holes and overall coverageextent
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Clutter Types
Clutter types
Dense Urban
Urban
Sub Urban
Rural
Water
Vegetation Industrial
Forest
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RF surveys
Each nominal has a search ring defined by the RFPlanner
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 thecoverage requirement in the area
Major obstructions and clutter type in variousdirections to be observed on RF survey
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RF surveys
Equipment required for RF Survey GPS
Digital Camera
Binoculars Magnetic Compass
There might be 3 or more candidates surveys forone site
Each candidate would have an RF survey form andpanoramic associated with it
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Drive Testing Drive testing is an important activity to get statistics & graphs oncoverage, quality & capacity in the downlink direction
Drive test setup DT tool, Engineering Handset, GPS,
accessories
Call in 2 modesDedicated 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
Selecting and Tuning
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g gPropagation Models
Parameters of propagationmodels must be adjusted forbest fit to actual drive-testmeasured data in the areawhere the model is applied
The figure at right shows drive-
test signal strengths obtainedusing a test transmitter at anactual test site
Tools automate the process ofcomparing the measured datawith its own predictions, and
deriving error statistics Prediction model parameters
then can be tuned tominimize observed error
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Drive Test Screen
What is Performance
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What is PerformanceOptimization?
The words performance optimization mean different things todifferent people, viewed from the perspective of their own jobs
System Performance Optimization includes many different smallerprocesses at many points during a systems life
recognizing and resolving system-design-related issues (cantbuild 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 possiblecall 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, andrecognizing problems before they become critical
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Optimization
Optimisation is an ongoing process of analysing network performance
against Quality of Service targets:
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Performance
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
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KPIs
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
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Radio Interface Optimization
Transmission Timing
Power Control
VAD Voice Activity Detector and DTX
Multipath Fading
Equalization
Diversity
Frequency Hopping
Antenna Parameters ( Height, Azimuth, Tilts )
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Antenna Tilts
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Antenna Tilts
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BenchmarkingSurveyed 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
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Overview
RF Planning Tool
Drive Test Tool
Optimization Tool
MapInfo
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