Basic of Gsm
-
Upload
neeraj-kumar -
Category
Documents
-
view
220 -
download
0
Transcript of Basic of Gsm
-
8/8/2019 Basic of Gsm
1/179
1
Global System
for Mobiles
GSM
-
8/8/2019 Basic of Gsm
2/179
2
TOPICS
GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
IDENTITIES USED IN GSM
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT
-
8/8/2019 Basic of Gsm
3/179
3
TOPICS
GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
IDENTITIES USED IN GSM
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT
-
8/8/2019 Basic of Gsm
4/179
4
Telecom Basics
Communication
Voice and Data
Analog and Digital Circuit Switched and Packet Switched
Media - Copper Wire, Co-axial cable, Air, Optical
Fiber
Networks -PSTN, ISDN, PDN and Mobile Networks
-
8/8/2019 Basic of Gsm
5/179
5
Background to GSM
1G : Advanced Mobile Phone Service (AMPS) Analog, Circuit Switched, FDMA, FDD
2G : Digital Advanced Mobile Phone Service (D-AMPS)
Digital, Circuit Switched, FDMA, FDD 2G : Global System for Mobile (GSM)
Digital, Circuit Switched, FDMA and TDMA, FDD
2G : Code Division Multiple Access (CDMA) Digital, Circuit Switched, FDMA, SS, FDD
-
8/8/2019 Basic of Gsm
6/179
6
GSM History
-
8/8/2019 Basic of Gsm
7/179
7
1982: Groupe Spcial Mobile (GSM)
created
1984: Description of GSM features
1985: List of recommendations settled
1987: Initial MoU (Memorandum ofUnderstanding) aside the drafting
of technical specifications was
signed by network operators of 13
countries:
1988: Validation and trials, of the radio
interface.
1991: First system trials are
demonstrated at the Telecom 91
exhibition.
1992: Official commercial launch of
GSM service in Europe. First
Launch in Finland
1993: The GSM-MoU has 62
signatories in 39 countries
worldwide.
1995: Specifications of GSM phase 2are frozen.
1999: GSM MoU joins 3GPP (UMTS)
GPRS Trials begins
2000: 480M GSM subscribersWorldwide
First GPRS Networks roll out
End 2002: 792M GSM subscribersWorldwide
Development of the GSM Standard
-
8/8/2019 Basic of Gsm
8/179
8
12 SERIESOPERATION ANDMAINTENANCE
01 SERIES
GENERAL 02 SERIESSERVICE ASPECTS
03 SERIESNETWORK ASPECTS
04 SERIESMS-BSS INTERFACE AND
PROTOCOLS
05 SERIES
PHYSICAL LAYER ON THERADIO PATH.
06 SERIESSPEECH CODINGSPECIFICATIONS
07 SERIESTERMINAL ADAPTERS
FOR MOBILE STATIONS
11 SERIESEQUIPMENT AND TYPE
APPROVAL SPECIFICATIONS
10 SERIESSERVICE INTERWORKING
09 SERIES
NETWORKINTERWORKING
08 SERIESBSS TO MSC INTERFACES
GSM Specifications
-
8/8/2019 Basic of Gsm
9/179
9
Increasing GSM Data Rates
Transmission Time GPRS = GeneralPacketRadioServiceHSCSD=HighSpeedCircuit SwitchedDataEDGE=Enhanced Data rate forGSM Evolution
UMTS = Universal Mobile Telecommunication System
10 sec 1 min 10 min 1 hour 0
UMTS
E/GPRS
ISDN
PSTN
GSM
webe-mail photo
web photoe-mail
web photo
video
clipreportphoto
web photoe-mail
videoclipreport
video
clipreport
videoclipreport
video
clipreport
-
8/8/2019 Basic of Gsm
10/179
10
through
putkbps
10 k
100 k64 k
1 M
2 M
1 k 1998 1999 2000 2001 2002
Time frame
UMTSUMTS
GPRSGPRS
HSCSDHSCSD
9.69.614.414.4
pack
et
GPRS=GeneralPacketRadioService
HSCSD=HighSpeedCircuit SwitchedData
EDGE=Enhanced Data rate forGSM Evolution
UMTS = Universal Mobile Telecommunication System
EDGE
circu
it
Wireless Data Technology Options
-
8/8/2019 Basic of Gsm
11/179
11
Circuit mode
Packet mode
AFDHCG
CG
CGCG
CG
DH
DH
AFDH
DH
AF
AF
AF
A
B
C
D
E
F
G
H
rcu t- w tc e or ac et-Switched
-
8/8/2019 Basic of Gsm
12/179
12
Multiple Access Technique
Multiple Access Achieved by dividing the available radio
frequency spectrum, so that multiple users can be given access at
the same time.
FDMA - Frequency Division Multiple Access ( eg: GSM each Frequency channel is 200KHz)
TDMA - Time Division Multiple Access
( eg: GSM each frequency channel is divided into 8 timeslots)
CDMA - Code Division Multiple Access
(eg: IS95- Each User data is coded with a unique code)
-
8/8/2019 Basic of Gsm
13/179
13
Duplex Technique
Duplex - How the up link and Down link of a user
is separated
FDD - Frequency Division Duplex
(eg: In GSM the up link and down link of a user is
separated by 45MHz )
TDD - Time Division Duplex
(the up link and down link of a user will be at the same
frequency but at different Time )
-
8/8/2019 Basic of Gsm
14/179
14
Cellular
Networking technology
that breaks geographicarea into cells shaped
like honey comb
Cell
is the radio coveragearea of one base
transceiver station
1
23
4
56
7
6
72
1
5
GSM Concepts -
Cellular Structure
-
8/8/2019 Basic of Gsm
15/179
15
What are the types in
GSM Network?
GSM-900 (Channels 125 operating band 900Mhz
carrier spacing 200khz spacing 45Mhz)
GSM -1800 (Channels 374 spacing 95Mhz)
GSM -1900(Used in USA)
-
8/8/2019 Basic of Gsm
16/179
16
GSM Band Allocations (MHz)
Carrier frequency = ARFCN =Absolute Radio Frequency Channel Number
Frequencies are in MHz
GSM systems Uplink Downlink Band DuplexSpacing
Duplexchannels
GSM 450
GSM 480
GSM 850
450.4-457.6
478.8-486
824-849
460.4-467.6
488.8-496
869-894
2x7.2
2x7.2
2x25
10
10
45
35
35
124
GSM 900
E-GSM (900)R-GSM (900)
890-915
880-915876-880
935-960
925-960921-925
2x25
2x352x04
45
4541
124
17440
GSM 1800GSM 1900
1710-17851850-1910
1805-18801930-1990
2x752x60
9580
374299
-
8/8/2019 Basic of Gsm
17/179
17
Frequency band
Uplink 890 - 915 MHz
Downlink 935 - 960MHz
Duplex Frequency Spacing 45MHz
Carrier separation 200KHzFrequency Channels 124
Time Slots /Frame(Full Rate) 8
Voice Coder Bit Rate 13Kbps
Modulation GMSKAir transmission rate 270.833333 Kbps
Access method FDMA/TDMA
Speech Coder RPE-LTP-LPC
GSM System specifications
-
8/8/2019 Basic of Gsm
18/179
18
Functions of the Radio Interface
BTS-1 BTS-2
BTS
Speech and user's data
Signaling
Communication
modeIdle mode
GSM F il R di B d S t
-
8/8/2019 Basic of Gsm
19/179
19
GSM Family Radio Band Spectrum
Uplink
Downlink
880 890 915 1710 1785
925 935 960 1805 1880
MHz
P-GSM
GSM 1800 GSM 1900
1850 1910
1930 1990
R-GSM
876
921
960
960
915
915
E-GSM
Uplink
Downlink
824 849
869 894 MHz
GSM 850
478.8 486
488.8 496
450.4 457.6
460.4 467.6
GSM 450 GSM 480
-
8/8/2019 Basic of Gsm
20/179
GS
-
8/8/2019 Basic of Gsm
21/179
21
GSM Time Division MultiplexFrame and Physical Channels
TS TS TS TS TS TS TS TS
0 1 2 3 4 5 6 7
Time4.615 ms
TDMA frame
Physical channel # 2 = recurrence of time-slot # 2
TDMA frame
0 9.23 ms
Time-slot
(frames repeat continuously)
TS TS TS TS TS TS TS TS
0 1 2 3 4 5 6 7
-
8/8/2019 Basic of Gsm
22/179
22
Physical Channel
MS3
////ARFCN
1 2 124FDMA
BTS
Without FH
0
TDMAs
TS7
n
n-1
n+1
MS2
MS1
timeBTS
With FH
-
8/8/2019 Basic of Gsm
23/179
23
Radio Link Aspects
From Speech to RF SignalBlah Blah Blah...Blah... Blah... Blah...
Digitizing and
Source Coding
Channel Coding
Interleaving
Ciphering
Burst Formatting
Modulating Demodulating
Burst De-formatting
Deciphering
De-interleaving
Channel Decoding
Source Decoding
-
8/8/2019 Basic of Gsm
24/179
24
GSM Delays Uplink TDMA Frames
Downlink TDMA
T T T T T T T T
R TMS1
R TMS2
Downlink
Uplink
Fixed transmit
delay of three
time-slots
R R R R R R R R
0 1 2 3 4 5 6 7
The start of the uplink TDMA
is delayed of three time-slotsBTS side
MSs side
BTS
TDMA Frame (4.615 ms)
-
8/8/2019 Basic of Gsm
25/179
Ti i Advance
-
8/8/2019 Basic of Gsm
26/179
26
TX BTS CAN WHAT GSM HOW WHEN WHAT
RX BTS yes the ms-isdn
RX MS1 CAN
TX MS1 yes
RX MS2 WHAT
TX MS2 the
RX MS3 GSM
TX MS3 ms-isdn
RX MS4 HOW
TX MS4
RX MS5 WHEN
TX MS5
RX MS6 WHATTX MS6
RX MS7
TX MS7
RX MS8
TX MS8
PropagationDelay
DD
+3TS
TA
Timing Advance2 - Without Timing Advance: Collision
Ad
-
8/8/2019 Basic of Gsm
27/179
27
CAN WHAT HOW WHEN WHAT
CAN
WHAT
HOW
WHEN
WHAT
TX BTS
RX BTS
RX MS1TX MS1
RX MS2TX MS2
RX MS3TX MS3
RX MS4TX MS4
RX MS5TX MS5
RX MS6TX MS6
RX MS7TX MS7
RX MS8TX MS8
yes
the
PropagationDelay
DD
+3TS - TA
yes the
Timing Advance = 2 * Propagation Delay
GSMms-isdn
ms-isdn
GSM
Timing Advance3 - With Timing Advance: No Collision
-
8/8/2019 Basic of Gsm
28/179
28
Uplink 890 MHz to 915 MHz
Down Link 935 MHz to 960 MHz
25 MHz divided into 125 channels of 200 KHzbandwidth
890.0 890.2 890.4 914.8 915.0
935.0 935.2 935.4 959.8 960.0
UP
DOWN
Access Techniques
-
8/8/2019 Basic of Gsm
29/179
29
Time Division Multiple Access
Each carrier frequency subdivided in time domain
into 8 time slots
Each mobile transmits data in a frequency, in itsparticular time slot - Burst period = 0.577 milli secs.
8 time slots called a TDMA frame. Period is .577 * 8
= 4.616 milli secs
0 1 2 3 4 5 6 7
4.616 ms
0.577 ms
Access Techniques ...
-
8/8/2019 Basic of Gsm
30/179
30
-
8/8/2019 Basic of Gsm
31/179
31
GSM in comparison with other
Standards GSM gives mobility without any loss in Audio quality
Encryption techniques used gives high security in the air
Interface and also use of SIM.
Bit Interleaving for high efficiency in Transmission.
Variable Power (Power budgeting- extend battery life)
Minimum Interference.
Features-CCS7 Signaling
SMS (Short Message Services)
Emergency Calls
CELL Broadcast
-
8/8/2019 Basic of Gsm
32/179
32
TOPICS
GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
IDENTITIES USED IN GSM
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT
-
8/8/2019 Basic of Gsm
33/179
33
GSM Network
OMC
AUC
HLR
MSC
EIRVLR
BSC
BTS
MS
External
PSTN &
PDN N/W
SS
BSS
Switching
System
Base StationSystem
MS Mobile Station
BTS Base transceiver System
BSC Base Station Controller
MSC Mobile Switching CenterHLR Home Location Register
VLR Visitor Location Register
EIR Equipment Identity Register
AUC Authentication Center
OMC Operation And Maintenance Center
-
8/8/2019 Basic of Gsm
34/179
Fundamentals
-
8/8/2019 Basic of Gsm
35/179
35
GSM utilizes two bands of 25 MHz. 890-915MHz band is used for uplink while the 935-960 MHz is used for downlink.
The frequency bands are divided into 200KHz wide channels called ARFCNs (AbsoluteRadio Frequency Channel Numbers) i.e.there are 125 ARFCNs out of which only 124are used.
Each ARFCN supports 8 users with each usertransmitting / receiving on a particular time
slot (TS).
Fundamentals
124
123
.
2
1
124
123
.
2
1
0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7
Data burst = 156.25 bit periods = 576.9 s
960 MHz
959.8MHz
200KHz
935 MHz
935.2 Mhz
915 MHz
200KHz
45 MHz
Downlink (TDMA frame) = 8 TS
Uplink (TDMA frame)
Delay
TS: Time slot
914.8 MHz
890.2 MHz
890 MHz
DOWNLINK
UPLINK
ThereforeTherefore 1 TDMA1 TDMA frame = 156.25 x 8 = 1250 bitsframe = 156.25 x 8 = 1250 bits
and has a duration of 576.92and has a duration of 576.92 s x 8 = 4.615 mss x 8 = 4.615 msThe technology
-
8/8/2019 Basic of Gsm
36/179
36
Channels : differentiating
between Physical and LogicalchannelsPhysical channels : The combination of an ARFCN
and a time slot defines a physical channel.
Logical channels : These are channels specified by
GSM which are mapped on physical channels.
Logical Channels on Air interface
-
8/8/2019 Basic of Gsm
37/179
37
Logical Channels on Air interface
LOGICAL
CHANNELS
COMMON
CHANNELS
DEDICATED
CHANNELS
BROADCASTCHANNELS
COMMONCONTROL
CHANNELS
DEDICATEDCONTROL
CHANNELS
TRAFFICCHANNELS
FCCH BCCHSCH SDCCH SACCH FACCH
PCH AGCHRACH TCH/F TCH/EFRTCH/H
-
8/8/2019 Basic of Gsm
38/179
38
FCCH
Logical channels
Logical channels
Control channels Traffic channels
BCH CCCHDCCH
Half
rate
Full
rate
SCH BCCH PCH AGCH RACH SDCCH SACCHFACCHCBCH
Frequency plan and importance of
-
8/8/2019 Basic of Gsm
39/179
39
Frequency plan and importance of
BCCH
B3
B2
B9
B6 B4
B1
Sectored
antennas
MS ( monitoring the
broadcast radio B1 in idle
mode )
F S B B B B .. F S .. .. I
F0 F50F2 F3 F4 F5 F10 F11F1
F,S,B exist in time slot 0 of each frame
B7
B8
B5
B10
B11
B12
frequency plan:
dcast frequencies :
roadcast channels = 48-62
opping channels = 32-46
-
8/8/2019 Basic of Gsm
40/179
40
What information does Broadcast Control channel
(BCCH) contain?
Serves as a Beacon for the Cell
Country Code (CC) and the Network Code (NC)
Location Area Identity (LAI)
List of neighboring cells which should be monitored by MS
List of frequencies used in the cell Cell identity
Back
Location Updates
-
8/8/2019 Basic of Gsm
41/179
41
Location Updates
Location Updates can be classified into
two:
Periodic Location Updates:
This occurs as per the timer set by the network operator.If the MS does not perform this update the MSC marksthe MS as Detached on the VLR.
Location Update on a handover:This occurs if during a handover the MS is moved into anew Location Area Code (LAC).
-
8/8/2019 Basic of Gsm
42/179
42Back
1. The MS is monitoring the BCCH and has all the decoded
information stored on the SIM ( including the LAC)2. As soon as the mobile is on a TCH it sends the signal
strength indication on the corresponding SACCH
3. The BSC monitors the signal strengths and on analysis
sends a handoff request on FACCH. The handoffprocess is completed on the FACCH.
4. After the completion of call, the MS starts monitoring the
BCCH again. On finding the LAC (stored on SIM) and that
decoded from the BCCH to be different , the MS requests
a Location Update through SDCCH.
-
8/8/2019 Basic of Gsm
43/179
-
8/8/2019 Basic of Gsm
44/179
44
Mobile Equipment(ME)
Frequency and Time Synchronization
Voice encoding and transmission
Voice encryption/decryption functions
Power measurements of adjacent cells
Display of short messages
International Mobile Equipment Identifier (IMEI)
-
8/8/2019 Basic of Gsm
45/179
45
SIM Portable Smart Card with memory (ROM-6KB to 16KB-A3/A8
algorithm, RAM- 128KB TO 256KB, EEPROM- 3KB to 8KB ) Static Information
International Mobile Subscriber Identity(IMSI)
Personal Identification Number (PIN)
Authentication Key (Ki)
Dynamic Information
Temporary Mobile Subscriber Identity(TMSI)
Location Area Identity (LAI)
Phone memories, billing information
Ability to store Short Messages received
SIM C d d GSM M bil
-
8/8/2019 Basic of Gsm
46/179
46
SIM-Card and GSM Mobile
Equipment
G S M
Global GSM MobilityCardThe Smart Card to use
+
SIM-Card
Contains:
- IMSI
=
-
8/8/2019 Basic of Gsm
47/179
47
The SIM-Card Functions
Microchip with storeduser information
Credit Card Size
Permanent data:- Unique mobile subscriber identitythrough IMSI number and PIMSI
for Packet Mode
- Authentication parameter Ki,
- Authentication algorithm A3,
- Generating encryption key Kcalgorithm A8,
- PIN code.
Removable data:- Temporary Mobile Subscriber Number,- Location Area Identification- Routing Area Identification (Packet mode)
SIM-Card
G S M
Global GSM MobilityCardThe Smart Card to use
25 mm
15 mm
-
8/8/2019 Basic of Gsm
48/179
48
Subscriber Identification
NatureInternational Mobile SubscriberIdentity
Conformity with E212
Mobile Station -Integrated Services DigitalNetwork Nb
Similar to ISDN,
Conformity with E164/E213
Nb. digits 3 2 max 10 1 to 3 2 to 4 total max 15
*This code does not identify a geographical area
but an operator
MS - ISDN
FormatMCC MNC MSIN
H1 H2 x x x ......... x x xCC NDC SN
M1 M2 x x x x x x x x
MeaningMobile
Country
Code
Mobile
Network
Code
Mobile Subscriber
Ident. Nb
H1 H2 = Identity of HLR
within the home PLMN
Country
Code
(where
subscription
has been made)
National
Destination
Code *
Mobile Subscriber
(national definition)
M1 M2 = nbr of logical HLR
IMSI
National Significant Mobile NumberIdentify a PLMN
worldwideIdentify the subscriber
of a PLMN
-
8/8/2019 Basic of Gsm
49/179
49
Description Stored in SIM Card
MobileCountryCode
3 digits
MobileNetworkCode
2 digits
Mobile SubscriberIdentification Number (MSIN)
H1 H2 X X X X X X
10 digits max
Location Area Code
LAC
Temporary MobileSubscriberIdentity
4 octets
G S M
Global GSM MobilityCardThe Smart Card to useMCC
=
208 (France)
234 (G-B)
262 (Germany)
404,405(India)
MNC
=
71(APBSNL)
72(TNBSNL)
20 (Byte) IMSI = 15 digits max
NMSI
LAI
MobileCountryCode
3 digits
MobileNetworkCode
2 digits
Routing Area Code
RAC
RAI
-
8/8/2019 Basic of Gsm
50/179
50
Country
Code
3 digits max
National
Destination
Code2 or 3 digits
SubscriberNumber (SN)
Roaming Number (RN)
HO-number
Must be dialed tomake a call to
mobile
subscriber
Is a PSTN-like
number to track the
MS that hands over
to another MSC
during call-in-state
Is a PSTN-likenumber used to
reach a roaming
MS
CC= 33 (France)
091(India)
001(US)
NDC = 9448(BSNL-karnataka)
9845,9880(Airtel)
9886(Hutch)
= 660, 661, 618 (Bytel)
M1 M2 X X X X X X X X X X X X X
10 digits max
Country
Code
National
Destination
Code
CountryCode
National
DestinationCode
MS-ISDN (15 digits max)
MSRN
Description Stored in the Network
-
8/8/2019 Basic of Gsm
51/179
-
8/8/2019 Basic of Gsm
52/179
52
International Mobile EquipmentIdentity (IMEI)
Type Approval
Code
TAC FAC SNR SP
Final Assembly
Code
Serial number (SPare)
TYPE
APPR
OVED
IMEI: * # 0 6 #351475 60 926514 4
-
8/8/2019 Basic of Gsm
53/179
53
MS Classmark
Revision level
RF power
Encryption algorithm
Frequency
Short message
LoCation Services
MS Positioning Method
8-PSK modulation
Multi-slot class
Multi-band
Classmark
Power classes
Class GSM400/850/900
1
2
3
45
8 W*
5 W
2 W**0.8 W
GSM1800
GSM1900
1 W**
0.25 W
4 W
1 W**
0.25 W
2 W
* Typical value for car mounted
** Typical value for handheld
Class
GSM
400/850/900
GSM
1800
GSM
1900
E1
E2
E3
2 W
0.5 W
0.2 W
1 W
0.4 W
0.16 W
1 W
0.4 W
0.16 W
For GMSK modulation
For 8-PSK modulation
-
8/8/2019 Basic of Gsm
54/179
54
Base Transceiver Station
(BTS) Handles the radio interface to the mobile station.
Consists of one or more radio terminals for transmission
and reception
Each Radio terminal represents an RF Channel
TRX and MS communicates over Um interface
Received data transcoding
Voice encryption/decryption
Signal processing functions of the radio interface
Uplink Radio channel power measurements
-
8/8/2019 Basic of Gsm
55/179
55
Home Location Register
(HLR) Stores user data of all Subscribers related to the
GMSC
International Mobile Subscriber Identity(IMSI)
Users telephone number (MS ISDN)
Subscription information and services
VLR address
Reference to Authentication center for key (Ki) Referred when call comes from public land network
-
8/8/2019 Basic of Gsm
56/179
56
Visitor Location Register
(VLR) Database that contains Subscriber parameters andlocation information for all mobile subscribers
currently located in the geographical area controlled
by that VLR
Identity of Mobile Subscriber Copy of subscriber data from HLR
Generates and allocates a Temporary Mobile
Subscriber Identity(TMSI)
Location Area Code
Provides necessary data when mobile originates call
-
8/8/2019 Basic of Gsm
57/179
57
Authentication Center (AuC)
Stores Subscriber authentication data called Ki, a
copy of which is also stored in in the SIM card
Generates security related parameters to authorize a
subscriber (SRES-Signed RESponse)
Generates unique data pattern called Cipher key (Kc)
for user data encryption
Provides triplets - RAND, SRES & Kc, to the HLR on
request.
-
8/8/2019 Basic of Gsm
58/179
58
EIR (Equipment Identity
Register) EIR is a database that contains a list of all valid
mobile station equipment within the network, where
each mobile station is identified by its International
Mobile Equipment Identity(IMEI). EIR has three databases.,
White list - For all known,good IMEIs
Black list - For all bad or stolen handsets
Grey list - For handsets / IMEIs that areon observation
-
8/8/2019 Basic of Gsm
59/179
-
8/8/2019 Basic of Gsm
60/179
60
GSM Entities and Signaling
Architecture
-
8/8/2019 Basic of Gsm
61/179
61
GSM Protocols
CM - Connection Management
MM - Mobility Management
RR - Radio resource
LAPDm - LAPD for mobile
LAPD - Link Access Procedure for D channel
BTSM - BTS Management Part
BSSAP - BSS Application Part (BSC - MSC)
DTAP - Direct Transfer Application Part (MS - MSC)
MAP - Mobile Application Part
MTP - Message Transfer part of SS7
SCCP - Signaling Connection Control Part of SS7
TCAP - Transaction Capabilities Application Part ISUP - ISDN User Part
-
8/8/2019 Basic of Gsm
62/179
62
Functional Plane of GSM
MS BTS BSC MSC/ HLR GMSC
VLR
MS BTS BSC MSC/VLR HLR GMSC
CC
MM
RR
Trans
-
8/8/2019 Basic of Gsm
63/179
-
8/8/2019 Basic of Gsm
64/179
64
Subscriber Identity -MSISDN The MSISDN is a GSM directory number which
uniquely identifies a mobile subscription in the Public
Switched Telephone Network (PSTN).
Calls will be routed from the PSTN and other networks
based on the Mobile Subscribers MSISDN number.
MSISDN= CC + NDC + SN
CC= Country Code (91)
NDC= National Destination Code(98370)
SN= Subscriber Number (12345)
-
8/8/2019 Basic of Gsm
65/179
65
International Mobile
Subscriber Identity [IMSI] Subscriber always identified within the GSM network
by the IMSI
This is used for all signaling in the PLMN stored in
SIM and HLR/VLR
The IMSI consists of three different parts
MCC = Mobile Country Code(3 Digits)
MNC = Mobile Network Code(2 Digits)
MSIN = Mobile Station Identification Number(Upto 10 digits)
-
8/8/2019 Basic of Gsm
66/179
66
Temporary Mobile Subscriber
Identity [TMSI] The TMSI is used for the subscribers confidentiality.
It should be combined with the LAI to uniquely
identify a MS.
Since the TMSI has only local significance (that is,
within the MSC/VLR area), the structure may be
chosen by each administration.
The TMSI should not consist of more than four
octets.
-
8/8/2019 Basic of Gsm
67/179
67
Mobile Station Roaming
Number[MSRN] HLR knows in what Service area the subscriber is
located.
In order to provide a temporary number to be used
for routing, the HLR requests the current MSC/VLR toallocate a Mobile Station Roaming Number(MSRN) to
the called subscriber and to return it.
At reception of the MSRN, HLR sends it to the MSC,
which now can route the call to the VLR where thecalled subscriber is currently registered.
-
8/8/2019 Basic of Gsm
68/179
68
International Mobile
Equipment Identity [IMEI] The IMEI is used for equipment identification. An IMEI uniquely identifies a mobile station as a piece or assembly of
equipment.
IMEI = TAC + FAC + SNR + sp
TAC= Type Approval Code (6 digits),determined by GSM body
FAC= Final Assembly Code (2 digits), identifies the manufacturer
SNR= Serial Number (6 digits), uniquely identifying all equipment within
each TAC and FAC
sp = Spare for future use (1 digit)
-
8/8/2019 Basic of Gsm
69/179
69
Location Area Identity
LAI identifies a location area which is a group of cells.. It is transmitted in the BCCH.
When the MS moves into another LA (detected by monitoring
LAI transmitted on the BCCH) it must perform a LU.
LAI = MCC + MNC + LAC
MCC= Mobile Country Code(3 digits), identifies the country
MNC= Mobile Network Code(1-2 digits), identifies the GSM-PLMN
LAC= Location Area Code, identifies a location area within a GSM
PLMN network. The maximum length of LAC is 16 bits,enabling 65536
different location areas to be defined in one GSM PLMN.
TOPICS
-
8/8/2019 Basic of Gsm
70/179
70
TOPICS
GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
IDENTITIES USED IN GSM
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT
-
8/8/2019 Basic of Gsm
71/179
71
Physical channel:One timeslot of a TDMA-frame on one carrier
is referred to as a physical channel.
There are 8 physical channels per carrier in
GSM,channel 0-7(timeslot 0-7)
Logical channel:
A great variety of information must be
transmitted between BTS and the MS,for e.g.
user data and control signaling.Depending
on the kind of information transmitted we
refer to different logical channels.These logical
channels are mapped on physical
channel.
Channel concept
L i l h l
-
8/8/2019 Basic of Gsm
72/179
72
FCCH
Logical channelsLogical channels
Control channels Traffic channels
BCH CCCHDCCH
Half
rate
Full
rate
SCH BCCH PCH AGCH RACH SDCCH SACCHFACCHCBCH
-
8/8/2019 Basic of Gsm
73/179
73
Broadcast channels BCH Broadcast Channel-BCH
Allotted one ARFCN & is ON all the time in every cell. Present in TS0 and
other 7 TS used by TCH.
Frequency correction channel-FCCH
To make sure this is the BCCH carrier.
Allow the MS to synchronize to the frequency. Carries a 142 bit zero sequence and repeats once in every 10 frames on the
BCH.
Synchronization Channel-SCH
This is used by the MS to synchronize to the TDMA frame structure within the
particular cell.
Listening to the SCH the MS receives the TDMA frame number and also theBSIC ( in the coded part- 39 bits).
Repeats once in every 10 frames.
-
8/8/2019 Basic of Gsm
74/179
74
Broadcast channels BCH ... BCH
The last information the MS must receive in order to receive calls or
make calls is some information concerning the cell. This is BCCH.
This include the information of Max power allowed in the cell.
List of channels in use in the cell.
BCCH carriers for the neighboring cells,Location Area Identity etc. BCCH occupies 4 frames (normal bursts) on BCH and repeats once
every Multiframe.
This is transmitted Downlink point to multipoint.
Cell Broadcast Channel - CBCH
Used for the Transmission of generally accessible information like ShortMessage Services(SMS)
-
8/8/2019 Basic of Gsm
75/179
75
Common Control Channels
CCCH CCCH- Shares TS-0 with BCH on a Multiframe.
Random access channel-RACH:
Used by Mobile Station for requesting for a channel. When the mobile
realizes it is paged it answers by requesting a signaling channel(SDCCH) on RACH. RACH is also used by the MS if it wants to
originate a call.
Initially MS doesnt know the path delay (timing advance), hence
uses a short burst (with a large guard period = 68.25 bits).
MS sends normal burst only after getting the timing advance info on
the SACCH.
It is transmitted in Uplink point to point.
-
8/8/2019 Basic of Gsm
76/179
76
Common Control Channels
CCCH .. Access Grant Channel-AGCH
On request for a signaling channel by MS the network
assigns a signaling channel(SDCCH) through AGCH. AGCH
is transmitted on the downlink point to point. Paging Channel-PCH
The information on this channel is a paging message
including the MSs identity(IMSI/TMSI).This is transmitted on
Downlink, point-to-multipoint.
-
8/8/2019 Basic of Gsm
77/179
77
Dedicated Control Channels-
DCCH Stand alone dedicated control
channel(SDCCH)
AGCH assigns SDCCH as signaling channel on request byMS.The MS is informed about which frequency(ARFCN) &
timeslot to use for traffic.
Used for location update, subscriber authentication, ciphering
information, equipment validation and assignment of TCH.
This is used both sides, up and Downlink point-point.
-
8/8/2019 Basic of Gsm
78/179
78
Dedicated Control Channels-
DCCH Slow associated control channel-SACCH
Transmission of radio link signal measurement, power control
etc.
Average signal strengths (RXLev) and quality of service(RXQual) of the serving base station and of the neighboring
cells is sent on SACCH (on uplink).
Mobile receives information like what TX power it has to
transmit and the timing advance. It is associated with TCH or
SDCCH
Fast associated control channel-FACCH
Used for Hand over commands and during call setup and
release. FACCH data is sent over TCH with stealing flag set
-
8/8/2019 Basic of Gsm
79/179
79
Traffic Channels-TCH
TCH carries the voice data.
Two blocks of 57 bits contain voice data in the normal
burst.
One TCH is allocated for every active call.
Full rate traffic channel occupies one physical
channel(one TS on a carrier) and carries voice data at
13kbps
Two half rate (6.5kbps) TCHs can share one physicalchannel.
GSM Channels
-
8/8/2019 Basic of Gsm
80/179
80
GSM Channels
Control ChannelsTraffic Channels(TCHs)
Full
rate
Half
rate
Dedicated Control
Channels
(DCCHs)
SlowFast
Downlink
Broadcast
Channels
(BCHs)
Common Control
Channels
(CCCHs)
Downlink Uplink
TCH /F TCH /H FCCH SCH BCCH PCH CBCH RACHAGCH SDCCH SACCHFACCH
Traffic Multiframing Signaling Multiframing Traffic Multiframing
(down uplink)
The Logical Channels on Radio Interface
-
8/8/2019 Basic of Gsm
81/179
81FACCH
BTS
0 1 2 3 4 5 6 7TS
MS
FCCH
SCH
BCCH
PCH
AGCH
CBCH
SDCCH
SACCH
TCH
TCH
FACCH
SDCCHSACCH
FCCH
SCH
BCCH
RACH
PCH
AGCH
RACH
CBCH
Synchronization
Frequency correction
Broadcast control
Access request
Subscriber paging
Answer to Access request
Broadcast info
Dedicated Signaling
Sys Info 5, 6 + SMS
Traffic (speech data)
Associated Signaling
Associated Signaling
Traffic (speech-data)
Radio Measurement + SMS
Dedicated Signaling
Broadcast info
M.S. Pre-synchronization
Access request
Subscriber paging
Answer to Access request
e og ca C a e s o ad o e ace
Logical Channel Description (1/2)
-
8/8/2019 Basic of Gsm
82/179
82
FACCH MESSAGES Connection establishment from
SDCCH to TCH
End validation of a SDCCH-TCH
commutation
Characteristics of the future used BS
after handover
Connection establishment to BS after
handover
Validation of an handover
SACCH MESSAGES
Measures:
-power level of the communication-quality level of the communication
- level on the beacon frequency ofthe neighboring cells
Timing Advance
Power Control
SMS
TCH MESSAGES
Speech Data
Handover Access message (uplink)
SDCCH MESSAGES
Request for a SDCCH assignment
Request for the end of channelassignment
Order of commutation from SDCCH to
TCH
SMS
Logical Channel Description (2/2)
-
8/8/2019 Basic of Gsm
83/179
83
FCCH MESSAGES
no message is sent (all bits 0)
BCCH MESSAGES
System Information type 1, 2, 2bis ,
2ter, 3, 4, 7, 8
(idle mode)
SCH MESSAGES
Frame Number
Base Station Identity Code (BSIC)
AGCH MESSAGES
For dedicated channel assignment:
- frequency number
-slot number- frequency hopping description-Timing Advance (1st estimation)-MS identification
PCH MESSAGES
messages containing a mobile
identity for a call, a short message
or an authentication
RACH MESSAGES
Service request:
-emergency call-answer to an incoming call-outgoing call-short message-call re-establishment- inscription
CBCH MESSAGES
Specific information
(weather, road information
g p
-
8/8/2019 Basic of Gsm
84/179
System Information
-
8/8/2019 Basic of Gsm
85/179
85
RACH Control parameters
- maxNumberRetransmission- numberOfSlotsSpreadTrans- cellBarred- callReestablishment- emergencyCallRestricted- notAllowedAccessClasses- AccessClassCongestion
BCCH allocation - Neighboring cells BCCHfrequencies in the same band
Extended BCCH allocation
- Neighboring cells BCCH frequencies inthe same band (complementary list)
- Neighboring cells BCCH frequencies inthe other band
- 2 ter indicator
- 5 ter indicator
LAI- Location Area Code- Mobile Country Code- Mobile Network Code
- cellIidentity
SYS INFO 1-4
SYS INFO 2/5
SYS INFO 2bis/5bi
SYS INFO 2ter/5te
SYS INFO 3-4/6
V10
System Information
SYS INFO: Parameters (1/2)
SYS INFO 3
SYS INFO 6
Cell Identity SYS INFO 3/6
System Information
-
8/8/2019 Basic of Gsm
86/179
86
Control Channel description- IMSI Attach Detach- noOfBlocksForAccessGrant- No Of Multiframe Between Paging
Cell Options
- Uplink Power Control- Dtx Mode (UL)- CellDtx Downlink (DL)
- Radio Link Timeout
Cell Selection Parameters- cellReselectHysteresis- msTxPwrMaxCCH- rxLevAccessMin
Cell Reselection Parameters
- cellReselInd- cellBarQualify- cellReselectOffset- temporaryOffset- penaltyTime- earlyClassmarkSending- power offset
SYS INFO 3
SYS INFO 3-4
SYS INFO 3-4or 7-8
SYS INFO 3
System Information SYS INFO: Parameters (2/2)
V10
Traffic and Control Multiframing
-
8/8/2019 Basic of Gsm
87/179
87
0 1 2 3 4 21 22 23 24 25 0 1 2 3 4 46 47 48 49 50
26 traffic frames = 120 ms
1 Hyperframe = 2,715,648 frames= 3h 28 min. 53 s 760 ms
0 1 2 3 5 2042 2043 2044 2045 2046 20474
1326
frames
0 1 2 3
46 47 48 49 500 1 3 42
22 23 2524
TS
0
TS
1
TS
2
TS
3
TS
5
TS
6
TS
7
TS
0
TS
1
TS
2
TS
3
TS
4
TS
5
TS
6
TS
7
TS
0
TS
1
TS
2
TS
3
TS
4
TS
5
TS
6
TS
7
TS
4
TS
0
TS
1
TS
2
TS
3
TS
4
TS
5
TS
6
TS
7
TS
0
TS
1
TS
2
TS
3
TS
4
TS
5
TS
6
TS
7
Frame
4.615 ms
Control channelTraffic channel
51 x 26 traffic frames = 6.12 s
26 x 51 control frames = 6.12 s
-
8/8/2019 Basic of Gsm
88/179
88
-
8/8/2019 Basic of Gsm
89/179
89
-
8/8/2019 Basic of Gsm
90/179
-
8/8/2019 Basic of Gsm
91/179
-
8/8/2019 Basic of Gsm
92/179
-
8/8/2019 Basic of Gsm
93/179
-
8/8/2019 Basic of Gsm
94/179
94
-
8/8/2019 Basic of Gsm
95/179
TOPICS
-
8/8/2019 Basic of Gsm
96/179
96
GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
IDENTITIES USED IN GSM
GSM CHANNELS
GSM RADIO LINK MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT
Speech
From Speech to Radio Transmission
-
8/8/2019 Basic of Gsm
97/179
97
Speech
Source
decoding
Channeldecoding
De-interleaving
Burst de-formatting
Deciphering
Demodulation
equalization
Digitizing and
source coding
Channel
coding
Modulation
Ciphering
Burst formatting
Interleaving
Step 1
Step 2
Step 3
Step 4
Transmission
Step 5
Step 6 Diversity
GSM R di Li k
-
8/8/2019 Basic of Gsm
98/179
98
GSM Radio Link
Speech Coding -Done at Transcoder of BSC and MS
The Linear Predictive Coder uses RPE-LTP(Regular Pulse
Excitation- Long Term Prediction)
Converts 64kbps voice to 13kbps(260 bits every 20ms) Channel Coding - Done at BTS and MS
Uses Convolution Coding and CRC (Cyclic Redundancy
Check)
Converts 13 kbps to 22.8 kbps (456 bits per 20ms)
-
8/8/2019 Basic of Gsm
99/179
-
8/8/2019 Basic of Gsm
100/179
Speech Quality Source Coding
-
8/8/2019 Basic of Gsm
101/179
101
Codec Type Mean Opinion Score Rate (kb/s)
(MOS)
PCM A law 4.25 64
GSM EFR 4.2 12.2
CDMA 13 4.2 13
D-AMPS 4 8
GSM FR 3.8 13
CDMA 8 3.4 8
Quality MOS Listening Effort Required
Excellent 5 Complete relaxation possible, no effort.
Good 4 Attention necessary, no appreciable effort.
Fair 3 Moderate effort.
Poor 2 Considerable effort.
Bad 1 No meaning understood with feasible effort.
-
8/8/2019 Basic of Gsm
102/179
Channel Processing in GSM
-
8/8/2019 Basic of Gsm
103/179
103
C
20 ms20 ms
A
A8
A7
A6
A5
B4
B3
B2
B1
B8
B7
B6
B5
C4
C3
C2
C1
57 bits
Information
1 1
CRL CRL
3 3
Tail Tail
26 bits
Training
8 Bursts
8 Sub blocks
of 57 bits
Source coding
Channel coding
Interleaving
Normalburst
20 ms
B
456 bitsA 456 bitsB 456 bitsC
57 bits
Information
A8B4A7B3A6B2A5B1 B8C4B7C3B6C2B5C1
Speech blocks
Codec dependent Codec dependentCodec dependent
Overview for Full Rate
-
8/8/2019 Basic of Gsm
104/179
104
Channel Processing in GSMO verview f or Half Rate
-
8/8/2019 Basic of Gsm
105/179
105
C
20 ms20 ms
A
A4
A3
A2
A1
B2
B1
B4
B3
C4
C3
C2
C1
4 Bursts
4 Sub blocks
of 57 bits
Source coding
Channel coding
Interleaving
20 ms
B
228 bitsA 228 bitsB 228 bitsC
A4B2
A3B1
B4C2
B3C1
Speech blocks
Codec dependent Codec dependentCodec dependent
Normalburst 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
456
Interleaving: TCH Full Rate
-
8/8/2019 Basic of Gsm
106/179
106
0 1 2 3 4 5 6 7 8 ... ... 452 453 454 455
0 1 2 3 4 5 6 78 9 10 11 12 13 14 15
448 449 450 451 452 453 454 455
57Rows
Divide 456 bits in 8 sub-blocks
765432107654 0 1 2 3
reordering&
partitioningout
diagonalinterleaving
456coded bits
burst
b0 b1 b56 b1 b56b0
bitinterleaving
Burst FormattingN l B
-
8/8/2019 Basic of Gsm
107/179
107
1 frame:4.615 ms
0 1 2 3 4 5 6 7
Guard
157 126 57
DATA
156.25 bits duration
(0.577 ms)
Training
sequence
33
DATA
8.25
S SGuard
Band
Burst
148 bits
Normal Burst
Burst Formats
-
8/8/2019 Basic of Gsm
108/179
108
Synchronization Burst
(SCH)
Tail Data Extended Training Sequence Data Tail
156.25 bits duration
(0.577 ms)
3 bits 39 encrypted bits 64 synchronization bits 39 bits 3 bits 8.25 bits
Guard
Period
Frequency Correction Burst
(FCCH)
Tail Data Tail
156.25 bits duration
(0.577 ms)
3 bits 142 fixed bits (0) 3 bits 8.25 bits
Guard
Period
Normal Burst
Burst Formats
-
8/8/2019 Basic of Gsm
109/179
109
Access Burst
Tail TrainingSequence Guard PeriodTail
156.25 bits (0.577 ms)
8 bits 36 encrypted bits 68.25 bits3 bits41 synch bits
Data
Dummy Burst
Tail Dummy Sequence Training Sequence Dummy Sequence Tail
3 bits 58 mixed bits 26 midamble bits 58 mixed bits 3 bits 8.25 bits
Guard
Period
156.25 bits (0.577 ms)
156.25 bits (0.577 ms)
13 bits 57 encrypted bits 1 26 bits 57 encrypted bits 3 bits 8.25 bits
Tail Data Training Sequence Data Tail Guard
Period
Normal Burst
-
8/8/2019 Basic of Gsm
110/179
-
8/8/2019 Basic of Gsm
111/179
-
8/8/2019 Basic of Gsm
112/179
112
Burst The information format transmitted during one
timeslot in the TDMA frame is called a burst.
Different Types of Bursts
Normal Burst
Random Access Burst Frequency Correction Burst
Synchronization Burst
-
8/8/2019 Basic of Gsm
113/179
T Training Sequence Coded Data T GP
156.25 bits 0.577 ms
-
8/8/2019 Basic of Gsm
114/179
114
T
3
Training Sequence
41
Coded Data
36
T
3
GP
68.25
Random Access Burst
T
3
Fixed Bit Sequence
142
T
3
GP
8.25
T
3
Coded Data
39
Training Sequence
64
Coded
Data 39
T
3
GP
8.25
Freq. Correc. Burst
Synchronization Burst
156.25 bits 0.577 ms
156.25 bits 0.577 ms
Transmission on the
di h l
-
8/8/2019 Basic of Gsm
115/179
115
radio channels A timeslot has a duration of .577 m seconds (148 Bits) 8 timeslots(8 x 0.577 = 4.62 ms) form a TDMA frame If a mobile is assigned one TS it transmits only in this time
slot and stays idle for the other 7 with its transmitter off, called
bursting
The start on the uplink is delayed from downlink by 3 TSperiods One TS = duration of 156.25 bits, and its physical contents is called a burst
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
DownlinkBTS > MS
UplinkMS > BTS
Offset
-
8/8/2019 Basic of Gsm
116/179
Frames Types On Um
-
8/8/2019 Basic of Gsm
117/179
117
Interface TDMA Frame
8 Time slots (Burst Period)
Length is 4.62 ms(8 * 0.577ms)
26-TDMA Multiframe
26 TDMA Frames (24 TCH, SACCH, Idle)
120 ms (26 * 4.62ms)
51-TDMA Multiframe
26 TDMA Frames (FCCH, SCH, BCCH, SDCCH, CCCH)
235.6 ms (51 * 4.62ms)
Frames Types On Um
-
8/8/2019 Basic of Gsm
118/179
118
Frames Types On Um
Interface Super Frame 51* 26 TDMA Frames
6.12 S
Hyper Frame 2048 * 51* 26 TDMA Frames
3 Hours, 28 Minutes, 53 Secs and 760 ms
-
8/8/2019 Basic of Gsm
119/179
M bilit M t
-
8/8/2019 Basic of Gsm
120/179
120
Mobility Management
Mobility Management (MM)
Location updating- normal,periodic, IMSI attach
Paging
Security Management Preventing unauthorized users- authentication
Maintaining Privacy of users- ciphering
Providing roaming facility
MM functionality mainly handled by MS, HLR,MSC/VLR.
Network Attachment
-
8/8/2019 Basic of Gsm
121/179
121
Cell Identification MS scans complete GSM frequency band for
highest power
Tunes to highest powered frequency and looks
for FCCH. Synchronizes in frequency domain
Get training sequence from SCH which followsFCCH. Synchronizes in time domain.
Accesses BCCH for network id, location area and
frequencies of the neighboring cells.
Stores a list of 30 BCCH channels
N t k Att h t
-
8/8/2019 Basic of Gsm
122/179
122
Network Attachment.. PLMN Selection
Get the operator information from SIM.
Cell Selection
Selected cell should be a cell of the selected PLMN
Signal strength should be above the threshold. Cell should not be barred
Location Update
Register with the network by means of location
updating procedures.
S it A th ti ti
-
8/8/2019 Basic of Gsm
123/179
123
Security - Authentication
Authentication center
provides RAND to Mobile
AuC generates SRES using
Ki of subscriber and RANDMobile generates SRES
using Ki and RAND
Mobile transmits SRES to
BTS
BTS compares receivedSRES with one generated
by AuC
MSKi RAND
A3
SRES
RAND
SRES
SRES
Auth Result
AuCBTSMS
S it Ci h i
-
8/8/2019 Basic of Gsm
124/179
124
Security - Ciphering
Data sent on air
interface ciphered
for securityA5 and A8
algorithms used to
cipher data
Ciphering Key isnever transmitted
on air
MSKi RAND
A8
Kc
MS Network
Um interface
A5 A5
Kc Kc
Data DataCipheredData
TOPICS
-
8/8/2019 Basic of Gsm
125/179
125
GSM CONCEPTS
GSM SYSTEM ARCHITECTURE IDENTITIES USED IN GSM
GSM CHANNELS
GSM RADIO LINK MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT
Communication Management
-
8/8/2019 Basic of Gsm
126/179
126
Co u cat o a age e t
(CM) Setup of calls between users on request Routing function i.e. Choice of transmission
segments linking users
Point to Point Short message services
-
8/8/2019 Basic of Gsm
127/179
PLMN Selection
-
8/8/2019 Basic of Gsm
128/179
128
No
automaticmode
The MS selects the firstPLMN from the preferredPLMNs list (if it is not in
the forbidden PLMNs list)
The user selects aPLMN from the
displayed PLMNs
manualmode
YesYes
Creation of a foundPLMN list
Is there an up to datefound PLMNs list?
End of PLMNselection
YesNo (automatic)
Cell Selectionsucceed?
Selection of thenext preferredpossible PLMN
No (manual)
PLMN Selection Constitution of the "Found PLMN list"
-
8/8/2019 Basic of Gsm
129/179
129
Listen to all the
frequencies of the GSMspectrum:power level measurement
and average on thesemeasurements
Select the best
frequenciesaccording to the
power level
(124 channels in GSM900, 374 in GSM 1800and 299 in GSM 1900
(30 in GSM 900 and 40 in GSM 1800)
Memorize thebeacon
frequencies in the
precedentselection
=> Create theFound PLMN list
Constitution of the Found PLMN list
List of the
Initial Cell Selection
-
8/8/2019 Basic of Gsm
130/179
130
Suitable cell:
- cell of the selected PLMN- cell not barred- C1 > 0
Eligible cell
List of thefrequencies of the
selected PLMN
IMSI Attach
Look for the cell with the bestC1 in the suitable cells list
Eligible cell?
Yes
Selection ofanother PLMN
No
C1 Computation for
eligible cells
Suitable cell?
Yes
No
Rejected?
Yes
PLMN set in theforbiddenPLMN list
End of Cell Selection
No
Cell Selection
-
8/8/2019 Basic of Gsm
131/179
131
BTS-2
BTS-1
This cell
BTS-3
BTS-4
BTS-5
1
1
1
1
2
3
45
Purpose: get synchronization
with the GSM network
prior establishing any communication.
FCCH
SCH
BCCH
1
Immediate AssignmentMS BSC MSC
BTS
-
8/8/2019 Basic of Gsm
132/179
132
MS BSC MSC
CM SERVICE REQUEST
SDCCH or TCH6
CHANNEL REQUEST
RACH
1
BTS
CHANNEL REQUIRED2
CHANNEL ACTIVATION3
IMMEDIATE ASSIGNMENTAGCH
5IMMEDIATE ASSIGNMENTCOMMAND5
CHANNEL ACTIVATION
ACK.4
Immediate
Assignment
LOCATION UPDAT. REQU.
SDCCH or TCH6
OR
Registration: the Very FirstLocation Update
-
8/8/2019 Basic of Gsm
133/179
133
LAI HLR
IMSI
VLR id
TMSI
IMSI
TMSI
Release
VLR
IMSI
TMSI
LAI
MSC
BTS
BSS
BSC
2
4
5
2
6
1
2
4
5
6
3
4TMSI
5
-
8/8/2019 Basic of Gsm
134/179
-
8/8/2019 Basic of Gsm
135/179
IMSI Attach
-
8/8/2019 Basic of Gsm
136/179
136
MSCBTS
BSS
BSC
VLR
3
4
5
4
6
1 CHANNELREQUEST
2IMMEDIATEASSIGNMENT
LOCATION UPDATING
REQUEST (IMSI Attach)3
5LOCATION UPDATING
ACCEPT (LAC, TMSI)
4Authentication
Procedure
-
8/8/2019 Basic of Gsm
137/179
Great Britain France Germany
Outgoing Call
-
8/8/2019 Basic of Gsm
138/179
138
FT
y
Telephone
network
Terminating
MSCBSC
BTS
BSS
VLR
Gateway
MSC
HLR
MS BSS MSC
PSTN
Mobile Originating Call
-
8/8/2019 Basic of Gsm
139/179
139
ACM = Address Complete Message
ANM = ANswerMessage
IAM = Initial Address Message
MS SC
CHANNEL REQUEST1
CM SERVICE REQUEST2 CM SERVICE REQUEST2
CALL PROCEEDING7CALL PROCEEDING
7
Assignmentprocedure7
IAM6
IMMEDIATE ASSIGNMENT2
ACM8
VLR
Ring
ANM10
ALERTING9
SETUP (basic) orEMERGENCY
4 SETUP4
CONNECT11
CONNECT ACKnowledge11
Authentication procedure3
Cipheringprocedure3
5
Dialing
RingingPath
Established
Ringing
SendingNumber
Mobile Terminating Call1 - Paging Principle
-
8/8/2019 Basic of Gsm
140/179
140
PSTN
LA1
LA2
BTS11
BTS21
BTS22
BTS31
BTS12
BTS23
HLR
4
3
5
1
2
5
6
6
BSC1
BSC2
BSC3
MSC/
VLRGMSC
Mobile Terminating Call2 - Detailed Procedure
-
8/8/2019 Basic of Gsm
141/179
141
VMSCBSS
VLR
Visitor PLMN
GMSC
HLR
Home PLMN
RoutingInformation
(MSRN)
6
IAM : Initial Address Message
MSISDN : Mobile Station Integrated Services Digital
network Number
MSRN : Mobile Station Roaming Number
IMSI : International Mobile SubscriberIdentity
GMSC : Gateway MSC
VMSC : VisitorMSC
TMSI : Temporary Mobile SubscriberIdentity
PN
InternationalSS7
ISDNIAM (MSRN)
7IAM
(MSISDN)2
Send
RoutingInformation
(MSISDN)
3
Provide Roaming Number
(IMSI)4
PAGE
(TMSI + LA)
9
Send infoto I/C
(MSRN)
8
Roaming Number
(MSRN)5
PAGINGREQUEST
(TMSI + LA)10
PAGING
REQUEST
(TMSI)
11
MSISDN
1
Mobile Terminating Call3 - End to End Procedure
-
8/8/2019 Basic of Gsm
142/179
142
MS BSS VMSC
CHANNEL REQUEST(LAC, Cell ID)
5
PSTN
IMMEDIATE ASSIGNMENT
(SDCCH or TCH)
6
PAGING REQUEST4
PAGING REQUEST
(TMSI or IMSI, LA)3
GMSC
IAM(MSISDN)
1IAM
(MSRN)2
CM SERVICE REQUEST
(Paging Response)7 PAGING RESPONSE
(TMSI or IMSI, LA)7
Authentication procedure8
Cipheringprocedure9
Address Complete Message11
ANswer Message12
Setup, Assignment, Alerting10
CONNECT12
Dialing
Ringing
PathEstablished
Call Release1 - Mobile Initiated
-
8/8/2019 Basic of Gsm
143/179
143
MS BSS MSC
Call in progress1
RELEASE COMPLETE4
PSTN
DISCONNECT2 DISCONNECT
2
RELEASE3RELEASE
3
RF Channel Releaseprocedure 8
Release5
RELEASE INDICATION7
CHANNEL RELEASE6
Releasetone
9
Call Release2 - PSTN Initiated
-
8/8/2019 Basic of Gsm
144/179
144
PSTN
On hook
Purpose:
informs the mobile
then releases radio
and network resources.
REL
RLC
MSC
BTS
BSS
BSC
1
1 1
12
33
4
55
4
6
2
Mobile Originated Call
-
8/8/2019 Basic of Gsm
145/179
145
Mobile Originated Call
Request for Service
Authentication
Ciphering
Equipment Validation
Call Setup
Handovers
Call Release
-
8/8/2019 Basic of Gsm
146/179
-
8/8/2019 Basic of Gsm
147/179
TOPICS
GSM CONCEPTS
-
8/8/2019 Basic of Gsm
148/179
148
GSM CONCEPTS
GSM SYSTEM ARCHITECTURE IDENTITIES USED IN GSM
GSM CHANNELS
GSM RADIO LINK MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT
Radio Resource Management
-
8/8/2019 Basic of Gsm
149/179
149
Radio Resource Management
Establish maintain and release stable connections
between MS and MSC
Manage Limited Radio and Terrestrial resources
Handover process is the sole responsibility of the RRLayer
Functions of RR layer are performed by MS and BSC
and partly by MSC
Radio Resource Management
-
8/8/2019 Basic of Gsm
150/179
150
Radio Resource Management
Power Control
Hand over Control
Discontinuous Transmission
Frequency Hopping
P C t l
-
8/8/2019 Basic of Gsm
151/179
151
BTS commands MS at different
distances to use different power levels
so that the power arriving at the BTSs Rx is
approximately the same for each TS
- Reduce interference
- Longer battery life
Power Control
Handover
-
8/8/2019 Basic of Gsm
152/179
152
Handover
Means to continue a call even a mobile crossesthe border of one cell to another
Procedure which made the mobile station really
roam
Handover causesRxLev (Signal strength , uplink or downlink)
RxQual (BER on data)
O & M intervention
Timing AdvanceTraffic or Load balancing
Handover Types
-
8/8/2019 Basic of Gsm
153/179
153
Handover Types
Internal Handover (Intra-BSS)
Within same base station - intra cell
Between different base stations - inter cell
External Handover (Inter-BSS)
Within same MSC -intra MSC
Between different MSCs - inter-MSC
Handover Types
MSCGMSC
-
8/8/2019 Basic of Gsm
154/179
154
BSC
BSC
BSC
BSC
MSC
MSC
C-1 C-2
C-3
C-4
-
8/8/2019 Basic of Gsm
155/179
-
8/8/2019 Basic of Gsm
156/179
Frequency Hopping
-
8/8/2019 Basic of Gsm
157/179
157
Frequency Hopping Frequency Hopping permits the dynamic switching of radio links from
one carrier frequency to another.
Base Band Hopping
At the BTS each the timeslot is shifted to another transceiver, which
is transmitting at the hop frequency. User will be connected to
different Transceivers depending on hop sequence.
Synthesis Hopping
At the BTS transceiver changes the frequencies used. The user will
be connected to only one transceiver.
Decreases the probability of interference
Suppresses the effect of Rayleigh fading
Wireless Data
Add-on to GSM network :
PCU; Packet Segmentation/re-assembly and scheduling Radio channel access control and management Transmission error detection and retransmission. Power control
S rf the Internet hile on the mo e
Enhanced Data rate for GSM Evolution EDGE is an enhancement of GPRS and CSD technologies. Based on the current GSM technology - same TDMA frame
structure, same bandwidth (200 kHz). Uses 8-PSK modulation instead of GMSK
Universal Mobile Telecommunication Standards Innovative Service Architecture : VHE Concept - providing the us
the same look and feel of its personalized services independent of
-
8/8/2019 Basic of Gsm
158/179
158
Wireless Data
98 99 2000 2001
GSM
DATAGSM
DATA
HSCSDHSCSD
GPRSGPRS
EDGEEDGE
UMTSUMTS
SIM
ToolkitSIM
Toolkit
WAPWAP
Data Application
Time
Circuit Switched technology
Packet Switched technology
Technology for Applications
SMS Data: 160 -numeric charactersUser Data Rate : 9.6kbps
One time slot over the air interface
High Speed Circuit Switched Data
User Data Rate:14.5kbps
Use multiple timeslots (max=8),hence max rate = 115.2kbps.
Needs a duplexor in MS for
simultaneous Tx and Rx
SGSN: GPRS mobility Encryption
ChargingGGSN : Interface to the PDN, Internet
Max user data rate : 21.4 kbps
Dynamic rate adaptation to suit the radio conditions at
that time ( 9.05 kbps, 13.4 kbps, 15.6 kbps 21.4 kbps)
W@P Gateway W@P ServiceW
@
P
F
o
n
e
InternetMobile Network
Surf the Internet while on the move
W@P Gateway : Adaptation of the information to the mobile Compression of the data Buffering of the information
Uses 8 PSK modulation instead of GMSK. Requires good propagation conditions. Allows upto 48 kbps (EGPRS) and upto 28.8 kbps (ECSD) on every
radio channel EDGE helps GSM-Only operators to compete with UMTS.
p p
network and terminal. Global Convergence : Fixed/Mobile, Telecom/Datacom, public/private
Mobile Multimedia driven market. Wideband bearers - 2GHz band ( 5 MHz per carrier), -max. 2Mbps
References
-
8/8/2019 Basic of Gsm
159/179
159
References
Wireless and Personal Communication Systems.Vijay.K.Garg and Wilkes
Overview of the GSM System and Protocol
Architecture, IEEE Comm. Magazine, Moe Rahnema.
The GSM System for Mobile Communications- Michel
Mouly & Marie-Bernadette Pautet
Overview of the GSM Comm- John Scourias.
Coverage or Traffic LimitationsTRAFFIC-
LIMITED
AREA COVERAGE-
-
8/8/2019 Basic of Gsm
160/179
160
AREA
(10000
subscribersper km2)
COVERAGE-
LIMITED
AREA
(-75 dBmat cell edge)
COVERAGE-LIMITED
AREA
(-70 dBm
at cell edge)
-
8/8/2019 Basic of Gsm
161/179
Different Types of CellsEXTENDED-CELL:
macro cell with system coverage
CONCENTRIC-CELL:
macro cell with system coverage
-
8/8/2019 Basic of Gsm
162/179
162
High sensitivity tointerference
Requires "secured"Frequency reuse pattern
High isolation frominterferences
A few Frequenciesintensively reused
MACRO-CELL:antenna radiating above roofs
---> Wide Coverage ( 35 km)
MICRO-CELL:
Antenna below the roofs
---> small coverage
PICO-CELL:
Antenna inside building
---> Very small coverage
extension ( 120 km) for coasts... limitation inside another macro
-
8/8/2019 Basic of Gsm
163/179
Cell Sectorization
-
8/8/2019 Basic of Gsm
164/179
164
TRI OMNI BI
Omni directional Site Antennas
-
8/8/2019 Basic of Gsm
165/179
165
Bi and Trisectorial Site Antennas
-
8/8/2019 Basic of Gsm
166/179
166
Link Budgeting
-
8/8/2019 Basic of Gsm
167/179
167
Calculation of the maximum coverage range of each cell in a specific environment.
Definition of planning tools parameters.
Based on the path loss calculation between the MS and the BS in both ways.
This calculation considers:
RF parameters of MS and BS,
system parameters (diversity gains...),
propagation parameters (shadowing), physical installation parameters (antenna height),
environment classification.
-
8/8/2019 Basic of Gsm
168/179
168
- What is the maximum EIRP?
- What are the losses intransmission and reception?
- Is diversity used? - What is the minimumequivalent sensitivity?
- What is the maximumequivalent output power?
- What are the body losses?
- Beyond which distance the
communication will cut off?- Is indoor coverage
guaranteed?
- Is frequency hopping used?
EIRP:Equivalent Isotropic Radiated Power
Link Budget Parameters Overview
-
8/8/2019 Basic of Gsm
169/179
169
Duplexer
Combiner
Power Amplifier
DLNA:Diversity Low Noise Amplifier
Specific Tx Cable
Losses
Tx PA Output
Power
Combiner losses
Rx Sensitivity
Rx Diversity Gain
DLNA conf.Standard conf.
Base Station
Tx PA Output Power
Other factors for MSBody LossesCommon cable losses
Propagation Parameters:
- Incar, Indoor penetration factors- Frequency 900, 1800, 1900 MHz
- Antenna Height
- Environment
Design Parameters:
Overlapping margin
Rx Sensitivity
Antenna Gain
MS
Rx Sensitivity
Common cable Losses
Antenna Gain
Radio Link
Link Budget Parameters BTS TX Power Amplifier
-
8/8/2019 Basic of Gsm
170/179
170
2.5W PA 25W PA 35W PA 20W PA 30W PA
GSM 900 S2000LS2000E
S4000 Indoor
S4000 Outdoor
S4000 Indoor S2000HS8000 Indoor
S8000 Outdoor
DCS 1800 S2000L S4000 IndoorS2000E
S2000H
S4000 Outdoor
S4000 Indoor
S8000 Indoor
S8000 Outdoor
PCS 1900 S2000L
S2000E
S2000H
S4000 Indoor
S4000 Outdoor
S8000 Outdoor
Link Budget Parameters Combiners
-
8/8/2019 Basic of Gsm
171/179
171
D
H2D
Hy/2
2-Way Hybrid Combiner with Duplexer2-Way Hybrid Combiner with Duplexer
4.5 dB Loss4.5 dB Loss
allows Synthesized Frequency Hopping
4-Way Cavity Combiner with
Duplexer
4-Way Cavity Combiner withDuplexer
allows Baseband Frequency Hopping
4.9 dB Loss4.9 dB Loss
C C C C
D
TX TX TX TXTXTX
Link Budget Parameters Cable Losses
-
8/8/2019 Basic of Gsm
172/179
172
At the BS, for a 7/8 foam dielectric coaxial cable:
4 dB/100 m (900 MHz),
6 dB/100 m (1800 MHz),
Common cable losses for 40 meters: 2.5 dB (900 MHz) and 3.5 dB (1800 MHz).
Jumpers (up and down the feeder)
0.5 dB (800 MHz),
1 dB (1800 MHz).
Link Budget Parameters BTS Antenna Gain
-
8/8/2019 Basic of Gsm
173/179
173
Omnidirectional antenna
Default 6.5 V with 11 dBi gain
Directional antenna for trisectorial site
Default 65 H / 6.5 V with 18 dBi gain
Link Budget Parameters Mobile Station Parameters
-
8/8/2019 Basic of Gsm
174/179
174
900 MHz 1800/1900 MHz
TX PA Output
Power33 dBm (2W) 30 dBm (1W)
RX Sensitivity -102 dBm
-2 dBi for Handheld
2 dBi for Car Kit
Body Loss
Antenna Gain
Common CableLoss
-100 dBm
0 dB for Handheld2 dB for Car Kit
3 dB for Handheld
0 dB for Car Kit
Link Budget PresentationParameters
Frequency 1800 MHzAntenna Gain (65 )
18 dBi
-
8/8/2019 Basic of Gsm
175/179
175
Base Height 40.0 m
Mobile Height 1.5 m
Environment Urban
RX TX
Mobile
Antenna Gain-2 dB
Cable Loss0 dB
Output Power
Sensitivity
-100 dBm
30 dBm
Jumper Loss
Feeder Loss
Sensitivity
-110 dBm
3 dB
Options
Rx Diversity Gain: 5 dB
Overlapping Margin: 0 dB
Penetration Factor
Body Loss 3 dB
15 dB
Outdoor Minimum Field
95%: -80 dBm
Coverage Range
95%: 810 m
0.5 dB
Base Station
Max TX Output Power
RXm RXd
44.8 dBm
Coupling system
TX loss4.5 dB
Link Budget Calculation
Exercise 1 : S8000 INDOOR: OPERATING FREQUENCY 1800 MHz
-
8/8/2019 Basic of Gsm
176/179
176
BTS M STX OUTPUT POWER 30.00 W (44.8
dBm)
1.00 W (30.0 dBm)
COMBINER LOSSES 5.0 dB None
RX SENSITIVITY -110.0 dBm -102.0 dBm
RX SENSITIVITY +
DIVERSITY
-115.0 dBm None
COMMON CABLE LOSSES 3.0 dB 0.0 dB
ANTENNA GAIN 18.0 dBm -2.0 dBm
BODY LOSSES 3.0 dB
OVERLAPPING MARGIN 0.0 dB
INDOOR PENETRATION
FACTOR
18.0 dB
FadingExample of Field Strength Variation for GSM 1800
-
8/8/2019 Basic of Gsm
177/179
177
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Distance (m)
FieldStrength
(dBm)
Measurement
Free Space
Zoom on
Short Term Fading
Long Term Fading
2 m
/2
Clutters
-
8/8/2019 Basic of Gsm
178/179
178
-
8/8/2019 Basic of Gsm
179/179