GSM Network Components

NETAJI SUBHAS CHANDRA
BOSE
TELECOM TEAINING CENTER
KALYANI
WELCOME YOU ALL

GSM
GLOBAL SYSTEM FOR
MOBILES.
SARAL
CHAKRABORTY JTO/
MOBILE NSCBTTC

Basic Components of GSM
BTS
MS
Um
BTS
BTS
BSC
Base Station Subsystem (BSS)
A-bis
A
BTS: Base Transceiver Station
BSC: Base Station Controller
HLR: Home Location Register
VLR: Visited Location Register
OMC: Operation & Maintenance Centre
EIR: Equipment Identity Register
AUC: Authentication Centre
Mobile
Services
Switching
Centre
(MSC)
HLR
EIR VLR OMC
AUC
F
H G
B
C
other MSCs
E
PSTN
ISDN
CSPDN
PSPDN
other VLRs
other BSSs
D
3

4
CELLULAR MOBILE CONCEPTS
WHAT IS A CELL ?
• A base station (transmitter) having a
number of RF channels is called a cell
• Each cell covers a a
limited number of mobile
subscribers within the cell
boundaries ( Coverage
area)

5
Cellular
Networking technology
that breaks geographic
area into cells shaped
like honey comb
Cell
is the radio coverage
area of one base
transceiver station
1
2
3
4
5
6
7
6
7
2
1
5
GSM Concepts -
Cellular Structure

Cells
•
•
•
•
A cell is the basic geographic
unit of cellular system.
The term cellular comes from
the honeycomb areas into
which a coverage region is
divided.
Cells are base stations
transmitting over small
geographic areas that are
represented as hexagons.
Each cell size varies
depending upon landscape.
Because of constraint imposed
by natural terrain and man-
made structures, the true
shape of cell is not a perfect
hexagon.

7
Cell Mode Layout
O
Omni-directional cell
Adopt omni-directional antenna
the overall directional propagation
characteristic is the same.
Directional cell
In general, cell with multi-sector is in
common use. Every directional cell
adopts directional antenna.

8
FREQUENCY REUSE PATTERN
*
1
2
3 f1
f2
f3
Three Sectored Cell
GSM = 1/3 ; 1 Cell Pattern & each cell with 3 sectors

9
FREQUENCY REUSE PATTERN
4/12
7/21

Cell Planning
•
–
–
Reusing frequencies
in different
geographic areas:
7 cell repeat pattern
is typical, but other
patterns are also
common.
7/21 cell pattern
A3
A1
A2
G3 G1
G2
C3
C1
C2
B3
B1
B2
F3
F1
F2
D3
D1
D2
E3
E1
E2
G3
G1
G2
F3
F1
F2
C3
C1
C2
A3
A1
A2
B3
B1
B2
E3
E1
E2
D3
D1
D2
7-cell reuse
pattern
Frequency
reuse

11
Basic Cellular Concept
base station
frequency re-use

12
“4  3” reuse mode:
one group includes 3 sectors /site ,12 frequency which
are distributed to 4 sites. Every site owns 3 frequency.
Frequency Reuse

13
Frequency Reuse
“3  3” reuse mode:
one group includes 3 sectors /site ,9 frequency
which are distributed to 3 sites. Every site owns 3
frequency.

For circulation to Trainees only
CLUSTER
•
•
•
The cells are grouped into clusters. The number of cells in a cluster must be
determined so that the cluster can be repeated continuously within the
covering area of an operator.
The typical clusters contain 4, 7, 12 or 21 cells. The number of cells in each
cluster is very important.
The smaller the number of cells per cluster is, the bigger the number of
channels per cell will be. The capacity of each cell will be therefore
increased. However a balance must be found in order to avoid the
interference that could occur between neighboring clusters. This
interference is produced by the small size of the cluster.
14

Cluster
1
3
2
3
2
7
1
6
4
5
K=3
K=7

16
A group of cells is called a cluster.
No frequencies are reused in a cluster.
4
5
6
7
2
3
1
1 2 3 4 5 6 7
GIVEN FREQ.
RESOURCE

17
1
4
2
1
3
5
6
7 2
6
3
4
5
7
D
R
CELLULAR PRINCIPLE N=7
1 2 3 4 5 6
7
Frequency Reuse Pattern “N”=7
Given Freq Resource
The spectrum allocated for a cellular network is limited. A cellular network can only
provide service to a large number of subscribers, if the channels allocated to it can
be reused. Channel reuse is implemented by using the same channels within cells
located at different positions in the cellular network service area.

GSM Speciﬁcations
GSM 900
Mobile to BS (UP-LINK) - 890 to 915 MHz
BS to Mobile (DOWN -LINK) - 935 to 960 MHz
Bandwidth - 25 MHz
GSM 1800 ( DCS )
Mobile to Cell (UP-LINK) - 1710 to 1785 MHz
Cell to Mobile (DOWN -LINK) - 1805 to 1880 MHz
Bandwidth - 75 MHz
RF Spectrum :

GSM Speciﬁcations
Carrier Separation - 200 kHz
No. of RF Carriers - 124
Access Method - TDMA/FDMA
Speech Coding - Full rate 13 Kbps
Half rate 6.5 Kbps
Duplex Distance - 45 MHz

20
Propagation characteristic
Cell coverage radius :
The higher the propagation
frequency
The higher the propagation loss
The smaller the cell coverage radius.
900MHz
1800MHz
1900MHz
Single Band Network
Frequency Resource
We know

21
Uplink 890 MHz to 915 MHz
Down Link 935 MHz to 960 MHz
25 MHz divided into 125 channels of 200 KHz bandwidth
890.0 890.2 890.4 914.8 915.0
935.0 935.2 935.4 959.8 960.0
UP
DOWN
Access Techniques

Duplexing Methodology
•
•


Duplexing is the technique by which the send and receive
paths are separated over the medium since transmission
entities (Modulator, Ampliﬁers, De-modulators ) are involved.
There are two types of duplexing:
Frequency Division Duplexing FDD
Time Division Duplexing TDD
22

Frequency Division Duplexing
•
–
–
•
Different Frequencies are used for send and receive paths
and hence there will be a :-
forward band and
reverse band.
Duplexer is needed if simultaneous transmission (send)
and reception (receive) methodology is adopted.
Frequency separation between forward band and reverse
band is constant .
23

Time Division Duplexing
•
•
TDD uses different time slots for transmission and reception
paths. Single radio frequency can be used in both the
directions instead of two as in FDD.
No duplexer is required. Only a fast switching synthesizer, RF
ﬁlter path and fast antenna switch are needed. It increases
the battery life of mobile phones.
24

Duplexing
•
•
Duplexing method used in GSM is FDD.
It means different frequency for uplink and downlink.
25

Frequency Band 2G Systems
900 MHz band-
890-915 MHz Uplink (Mobile to Cell)
935-960 MHz Downlink (Cell to Mobile)
1800 MHz band-
1710-1785 MHz Uplink ( Mobile to Cell)
1805-1880 MHz Downlink (Cell to
Mobile)
26

Channel Spacing
•
•
This indicates separation between adjacent carrier
frequencies.
In GSM, this is 200 kHz.
27

Access Methods
•
•
•
Because radio spectrum is a limited resource shared
by all users, a method must be devised to divide up
the bandwidth among as many users as possible.
GSM chose a combination of TDMA/FDMA as its
method.
The FDMA part involves the division by frequency of
the total 25 MHz bandwidth into 124 carrier
frequencies of 200 kHz bandwidth.
28

Access Methods
•
•
•
One or more carrier frequencies are then assigned to each
BS.
Each of these carrier frequencies is then divided in time,
using a TDMA scheme, into eight time slots.
One time slot is used for transmission by the mobile and
one for reception. They are separated in time so that the
mobile unit does not receive and transmit at the same time.
29

GSM Concepts - Access Techniques
•
–
–
Frequency Division Multiple Access (FDMA)
Uplink/Downlink bands divided into 200KHz bandwidth of 125
carrier frequencies
Mobile and BTS in a cell communicate in a particular carrier
frequency
890.0 890.2 890.4 914.8 915.0
935.0 935.2 935.4 959.8 960.0
UP
DOWN
30

Case of GSM 900:ARFCN
•
•
Each frequency carrier has been given a number called
as ARFCN (Absolute Radio Frequency Carrier Number)
They can be from 1 to 124
Frequency =890.2+0.2*(N-1) (N=ARFCN)
31
N=70
Frequency=904MHz

Duplex Distance
•
•
•
The duplex distance is 45 MHz.
Duplex distance is the distance between the uplink and
downlink frequencies.
A channel has two frequencies, 45 MHz apart.
32

0 1 2 3 4 5 6 7
4.616 ms
0.577 ms
GSM Concepts - Access Techniques
•
–
–
–
–
Time Division Multiple Access
Each carrier frequency subdivided in time domain into 8 time slots
Each mobile transmits data in a frequency, in its particular time
slot - Burst period = 0.577 milli secs.
8 time slots called a TDMA frame.
Period of a frame is (0 .577 * 8 = 4.616 ms)
33

35
AuC
MS
MS
BTS
BTS
BTS
BSC
BSC
MSC
MSC
VLR
VLR
GMSC
HLR
PSTN
EIR
Um
Abis
Abis
A
A
OMC Server
Um
GSM - Network Structure
B
E
E
X.25
C
F
H
X.25

36
GSM Network
OMC
AUC
HLR
MSC
EIR
VLR
BSC
BTS
MS
External
PSTN &
PDN N/W
SS
BSS
Switching
System
Base Station
System
MS Mobile Station
BTS Base transceiver System
BSC Base Station Controller
MSC Mobile Switching Center
HLR Home Location Register
VLR Visitor Location Register
EIR Equipment Identity Register
AUC Authentication Center
OMC Operation And Maintenance Center

37
GSM Architecture
HLR
VLR
EIR
AUC
MSC
B
S
C
B
S
C
SMSC
PSTN
VMSC
Mobile
Station
GSM
Air
interface
OMCR
TRAU
Base Station System
Network and
switching subsystem
A interface SS7 /
speech
SS7
X.25
BTS
BTS
BTS
BTS
BTS
BTS
Abis
interfac
e
A
interfac
e
OMCS

38
Mobile Equipment(ME)
•
•
•
•
•
Frequency and Time Synchronization
Voice encoding and transmission
Power measurements of adjacent cells
Display of short messages
International Mobile Equipment Identiﬁer (IMEI)

39
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

Subscriber Identification
Nature
International Mobile Subscriber Identity
Mobile Station -
Integrated Services Digital Network
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
Format MCC MNC MSIN
H1 H2 x x x ......... x x x
CC NDC SN
M1 M2 x x x x x x x x
Meaning
Mobile
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 Number
Identify a PLMN
worldwide
Identify the subscriber
of a PLMN

Description Stored in SIM Card
Mobile
Country
Code
3 digits
Mobile
Network
Code
2 digits
Mobile Subscriber Identiﬁcation Number (MSIN)
H1 H2 X X X X X X
10 digits max
Location Area Code
LAC
G S M
Global GSM Mobility
Card
The Smart Card to use
MCC
=
208 (France)
234 (G-B)
262 (Germany)
404,405(India)
MNC
=
71(APBSNL)
72(TNBSNL)
20 (Bytel) IMSI = 15 digits max
MSI
N
LAI
Mobile
Country
Code
3 digits
Mobile
Network
Code
2 digits
Routing Area Code
RAC
RAI

42
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
Signal processing functions of the radio interface
Uplink Radio channel power measurements

43
Base Station Controller (BSC)
•
•
–
–
•
•
•
•
•
•
Provides all the control functions and physical
links between the MSC and BTS
External Interfaces
‘Abis’ interface towards the BTS
‘A’ interface towards the MSC
Monitors and controls several BTSs
Management of channels on the radio interface
Alarm Handling from the external interfaces
Performs inter-cell Handover
Switching from ‘Abis’ link to the ‘A’ link
Interface to OMC for BSS Management

44
Mobile Switching Center (MSC)
•
•
•
•
•
•
•
Performs call switching
Interface of the cellular network to PSTN
Routes calls between PLMN and PSTN
Queries HLR when calls come from PSTN to mobile
user
Inter-BSC Handover
Paging
Billing

45
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

46
Visitor Location Register (VLR)
•
•
•
•
•
•
Database that contains Subscriber
parameters and location 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

47
Authentication Center (AuC)
•
•
•
Stores Subscriber authentication data called Ki, a
copy of which is also stored in the SIM card
Generates security related parameters to authorize
a subscriber .
Generates unique data pattern called Cipher key (Kc)
for user data encryption

48
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 IMEI’s
Black list - For all bad or stolen handsets
Grey list - For handsets/IMEI’s that are on
observation

50
GSM Architecture
HLR
VLR
EIR
AUC
MSC
B
S
C
B
S
C
SMSC
PSTN
VMSC
Mobile
Station
GSM
Air
interface
OMCR
TRAU
Base Station System
Network and
switching subsystem
A interface SS7 /
speech
SS7
X.25
BTS
BTS
BTS
BTS
BTS
BTS
Abis
interfac
e
A
interfac
e
OMCS

51
Channels : differentiating between
Physical and Logical channels
Physical 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.

52
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

53
Logical Channels on Air interface
LOGICAL
CHANNELS
COMMON
CHANNELS
DEDICATED
CHANNELS
BROADCAST
CHANNELS
COMMON
CONTROL
CHANNELS
DEDICATED
CONTROL
CHANNELS
TRAFFIC
CHANNELS
FCCH BCCH
SCH SDCCH SACCH FACCH
PCH AGCH
RACH TCH/F TCH/H

54
FCCH
Logical channels
Logical channels
Control channels Traﬃc channels
BCH CCCH DCCH
Half
rate
Full
rate
SCH BCCH PCH AGCH RACH SDCCH SACCH FACCH
CBCH

55
Broadcast channels BCH
•
–
•
–
–
–
•
–
–
–
Broadcast Channel-BCH
Alloted 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 the BSIC ( in the coded part- 39 bits).
Repeats once in every 10 frames.

56
Broadcast channels BCH ...
•
–
–
–
–
–
•
–
BCCH
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.
Cell Broadcast Channel - CBCH
Used for the Transmission of generally accessible information
like Short Message Services(SMS)

57
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 doesn’t 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.

58
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 MS’s identity(IMSI/TMSI).This is transmitted
on Downlink, point-to-multipoint.

59
Dedicated Control Channels-DCCH
•
•
•
•
Stand alone dedicated control channel(SDCCH)
AGCH assigns SDCCH as signaling channel on
request by MS.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.

60
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

61
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
physical channel.

62
GSM Channels
Control Channels
Traffic Channels
(TCHs)
Full
rate
Half
rate
Dedicated Control
Channels
(DCCHs)
Slow
Fast
Downlink
Broadcast
Channels
(BCHs)
Common Control
Channels
(CCCHs)
Downlink Uplink
TCH /F TCH /H
FCCH SCH BCCHPCH CBCH RACH
AGCH SDCCH SACCH
FACCH
Traffic Multiframing Signaling Multiframing Traffic Multiframin
(down uplink)
GSM Channels

Cell Selection
BTS-2
BTS-1
This cell
BTS-3
BTS-4
BTS-5
1
1
1
1
2
3
4
5
Purpose: get synchronization
with the GSM network
prior establishing any communication.
FCCH
SCH
BCCH
1

Registration: the Very First Location
Update
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
4
TMSI 5

66
ACM = Address Complete Message
ANM = ANswer Message
IAM = Initial Address Message
MS BSS MSC
CHANNEL REQUEST
1
PSTN
CM SERVICE REQUEST
2 CM SERVICE REQUEST
2
CALL PROCEEDING
7
CALL PROCEEDING
7
Assignment procedure
7
IAM
6
IMMEDIATE ASSIGNMENT
2
ACM 8
VLR
Ring
ANM 10
ALERTING9
SETUP (basic) or
EMERGENCY
4 SETUP
4
CONNECT 11
CONNECT ACKnowledge
11
Authentication procedure
3
Ciphering procedure
3
5
Dialing
Ringing
Path
Established
Ringing
Sending
Number
Mobile Originating Call

67
Radio Resource Management
•
•
•
•
Power Control
Hand over Control
Discontinuous Transmission
Frequency Hopping

68
BTS commands MS at different
distances to use different power levels
so that the power arriving at the BTS’s Rx is
approximately the same for each TS
- Reduce interference
- Longer battery life
Power Control

69
Handover
Means to continue a call even a mobile crosses
the border of one cell to another
Procedure which made the mobile station really
roam
Handover causes
RxLev (Signal strength , uplink or downlink)
RxQual (BER on data)
Timing Advance
Traﬃc or Load balancing

70
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

71
Discontinuous Transmission
•
•
•
•
Discontinuous Transmission(DTX) allows the
radio transmitter to be switched off most of the
time during speech pauses.
A Silence Indicator Block is transmitted at
500bps, which generates a comfort noise
Down Link interference is decreased.
Up link battery is saved

72
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

GPRS (2.5G )
•
•
•
•
•
•
•
GPRS Stands for General Packet Radio Service.
GPRS is packet-switched Network.
GPRS provides packet switched data services to
the mobile station (MS).
GPRS is an add-on technology of GSM.
Data Rate supported by GPRS is 115 Kbps.
GPRS use free unused Time Slot of GSM to
provide data service to MS.
Multiple Time Slot ( Maximum 8) can be allotted
to a single user.

GPRS Technique
Time
Slots
14.4
Kbps
115 Kbps
14.4
Kbps
14.4
Kbps
14.4
Kbps
14.4
Kbps
14.4
Kbps
14.4
Kbps
14.4
Kbps

GPRS Network
BTS BSC
HLR
EIR
MSC/
VLR GMSC
AUC
BSS MSS
BTS BSC
PCU
SGSN GGSN
PSTN/
other
GMSC
BSS
External
Packet
Data
Network

2.75G : EDGE
•
•
•
•
•
EDGE is a digital mobile technology which was
invented by AT&T and is an extended version of
GSM.
The idea behind EDGE is to obtain even higher
data rates on the current 200 KHz GSM carrier,
by changing the type of the modulation used.
It supports fast transmission rate of 384 Kbps
EDGE is also termed as IMT-SC or single carrier.
.
One Symbol for every 3 bits. Thus, EDGE Rate =
3x GPRS Rate.

EDGE Concept
voice voice voice voice voice
voice voice
voice
voice voice Free
TS
Data
Free
TS
Standard GSM Transceiver
EDGE Transceiver
One Time Slot can
carry bits of 3 time
Slot.

EDGE
TRAU
Evolution to EDGE
BTS BSC
HLR
EIR
MSC/
VLR
GMSC
AUC
BSS MSS
BTS BSC
PCU
SGSN GGSN
PSTN/
other
GMSC
External
Packet
Data
Network
TRAU :Transcoder and Rate Adaptation Unit
PCU : Packet Control Unit
SGSN : Serving GPRS Support Node
GGSN : Gateway GPRS Support Node

RADIO PARAMETERS
TEMS-(Speech)

• To know the meaning of parameters in windows like :
a) Current Channel
b) Radio parameters
c) Serving + Neighbours
Objective

Current Channel
• Deﬁnitions:
Time: It is system time of computer.

CurrentChannel
• Cell name: It
displays the name
of the sector which
is serving
according to the
cellﬁle that is
loaded in TEMS.

Current Channel
CGI : It stands for the Cell Global Identity which is
unique for every sector of the site. It
consists of MCC, MNC, LAC, CI.
MCC: Mobile Country Code 0 – 999 (e.g. 404),
MNC: Mobile Network Code 0 – 99 (e.g. 98)
LAC : Location Area Code 0 -65535 (e.g.
5101)
CI: Cell Identity 0 – 65535 (e.g. 11001)

Current Channel
• Cell GPRS Support: Tells sector is
having GPRS or not. Values are Yes or
No .

Current Channel
• Band : It tells in which Freq. Band mobile is
operating e.g. GSM 900/ 1800.

Current Channel
• BCCH ARFCN: It tells by which BCCH is the
mobile station getting served.

Current Channel
• TCH ARFCN: On which Traﬃc Freq. call is
going on.

Current Channel
• BSIC (Base Station Identity Code) : It is
combination of Network Color Code (NCC)
(0 – 7) & Base Station Color Code (BCC) (0 –
7). e.g. 62. It is decoded by mobile on every
Sync. Channel Message.

Current Channel
• Mode: It is shows in which state is mobile
operating, Idle, Dedicated & Packet.

Current Channel
• Time slot: On which time slot of current
TCH call is going on. Viz. time slot no. of
TRX.

Current Channel
• Channel Type: Type of channel mobile is
getting now. Like BCCH / SDCCH/8 +
SACCH/C8 or CBCH / TCH/F +FACCH/F
+SACCH/F.

• Channel Mode : Shows mode of coding like
Speech Full Rate of Half Rate.
Current Channel

• Speech Codec: It shows FR for Full Rate,
HR for Half Rate & EFR for Enhanced Full
Rate.
Current Channel

• Ciphering Algorithm : It shows ciphering
algorithm used by the system to protect
data for privacy. E.g. Cipher by A5/2.
Current Channel

• Sub Channel Number: It is displayed at a
time when mobile is on dedicated mode at
time of call setup when it is getting SDCCH
at that time it shows which SDCCH it is
getting out of 8 available. E.g. 2.
Current Channel

• Hopping Channel : It shows that current
sector is having hopping feature or not.
Values are Yes or No.
Current Channel

• Hopping Frequencies : It displays no. of
freq. on which mobile is allowed to hop. viz.
MA List for hopping of that sector.
Current Channel

• Mobile Allocation Index Offset (MAIO):
It is the number which tells from which freq.
from given MA list for sector hopping has to
be started. E.g. 0 means sector will start
from ﬁrst freq. to hop.
Current Channel

• Hopping Sequence Number (HSN) :
Indicates sequence in which frequencies are
allowed to hop from the MA List. 0- 63. 0 for
Cyclic Hopping, 1 – 63 random hopping
sequences.
Current Channel

Radio Parameters
• RxLev : Receiving level in terms of dBm that
mobile is receiving from the site. Range of
-30 dBm to -110dBm.

• RxQual : Quality of voice which is measured
on basis of BER. Range of RxQual 0 -7.
Radio Parameters

• FER : Frame Erasure Rate it represents the
percentage of frames being dropped due to
high number of non-corrected bit errors in
the frame. It is indication of voice quality in
network.
Radio Parameters

• BER Actual : Ratio of the number of bit
errors to the total number of bits
transmitted in a given time interval. BER is a
measure for the voice quality in network..
Depending on BER RxQual is measured. E,g,
BER 0 to 0.2 % corresponds to RxQual 0.
Max. BER countable and useful is up to 12.8
% which corresponds to RxQual of max. 7.
Radio Parameters

• FER Actual : It is the FER calculated
over the blocks which actually carry
the speech data.
Radio Parameters

• SQI : SQI is a more sophisticated measure
which is dedicated to reﬂecting the quality of
the
speech (as opposed to radio
environment conditions). This means that
when optimizing the speech quality in your
network, SQI is the best criterion to use. SQI
is updated at 0.5 s intervals. It is computed
on basis of BER and FER.
Radio Parameters

• C/I : The carrier-over-interference ratio is the
ratio between the signal strength of the
current serving cell and the signal strength
of undesired (interfering) signal components.
It should be atleast > 9 .
Radio Parameters

•
•
AMR C/I :
It is the threshold value of C/I at
which the mobile will request for
codec change
Radio Parameters

• MS Power Control Level : Displays range
of power control from 0 to 8 depending upon
network design. E.g. 0 means no power
control and 1 means level that is deﬁned by
operator eg 2 dBm
Radio Parameters

• DTX : Discontinuous transmission (DTX) is
a mechanism allowing the radio transmitter
to be switched off during speech pauses.
This feature reduces the power consumption
of the transmitter, which is important for
MSs, and decreases the overall interference
level on the radio channels affecting the
capacity of the network..
Radio Parameters

• TA : Value that the base station calculates
from access bursts and sends to the mobile
station (MS) enabling the MS to advance the
timing of its transmissions to the BS so as to
compensate for propagation delay. Value of
0 means MS in radius of 550mt. From BS.
Radio Parameters

• RL Timeout Counter (Cur) : This
parameter deﬁne the maximum value of the
radio link counter expressed in SACCH
blocks. Range of 4 – 64 in step size of 4. it
shows current value of RLT. When it reaches
zero it results in normal DROP Call.
Radio Parameters

• RL Timeout Counter (MAX) : This
parameter deﬁne the maximum value of the
radio link counter expressed in SACCH
blocks. Range of 4 – 64 in step size of 4.
Radio Parameters

• MS Behavior Modiﬁed : This window
shows current settings for the mobile
station, for instance whether handover is
disabled or multiband reporting enabled.
Radio Parameters

•
•
•
•
•
•
Cell Name : Name that describes the neighboring cell as per the cellﬁle.
ARFCN: Channel number mobile receives as neighbor.
BSIC : BSIC of the neighboring cell.
RxLev :Receiving Level in dBm of neighboring cell.
C1 & C2 : These are the cell path loss criterion and cell reselection criteria. Valid during idle
mode of mobile station.
C31 & C32 : GPRS signal strength threshold criterion C31 and GPRS cell ranking criterion
C32. Valid both in packet idle and packet dedicated mode.
Radio Parameters

3G Offers
•
–
–
–
•
•
•
•
•
The data rate supported by 3G networks
144 kbps in satellite and rural outdoor,
384 kbps in urban outdoor
2Mbps in indoor and low range outdoor.
Enhanced voice quality
Increased network eﬃciency and capacity
New voice and data services and capabilities
3G mobile offers multimedia applications and
mobile internet access.
3G delivers more new features such as Web
browsing, e-mail, TV streaming, video conferencing .

Spectrum Allocation for IMT-2000
•
•
•
•
The following spectrum allocations made for
IMT-2000 by ITU.
1885-2025 MHz and 2110-2200 MHz (Core
band)
1710-1885 MHz and 2500-2690 MHz
(Additional band).
806-960 MHz (Additional band)

3G Migration Path
GSM GPRS EDGE UMTS
W-CDMA
IS 95A
CDMA One
IS 95B
CDMA One
CDMA
2000 1X
2G 2.5G 2.75G 3G
CDMA
2000 3X
2G 2.5G 2.75G 3G
14.4
Kpps
115Kbps 384 Kbps 2 Mbps
14.4
Kpps
64Kbps 114 Kbps 2 Mbps

UMTS
( Universal Mobile Telecommunication System)
•
•
•
•
•
UMTS use W-CDMA in the RAN
W-CDMA use 5 Mhz Carrier entirely for each user.
Duplexing Method is FDD ( Frequency division
duplexing : separate carrier for uplink and
downlink)
The frequency band is 1.8 - 2.5 GHz
It provides higher data transmission rates up to 2
Mbps

Advantage of W-CDMA







Higher voice capacity
Better spectrum eﬃciency,
Wider coverage,
Support for all types of services (circuit, packet
and multimedia)
5 Mhz is more immune to fading.
Backward compatible to GSM.
Support Hand-off to and from GSM.

EDGE
TRAU
BTS BSC
HLR
EIR
MGW GMSC
AUC
BTS BSC
PCU
SGSN GGSN
PSTN/other
GMSC
External
Packet Data
Network
Node B
( 3G BTS)
RNC
MSC-S
USIM
UMTS Architecture
RNC : Radio Network Controller
MGW : Media Gateway
MSC –S : MSC Server
UTRAN : UMTS Trrestrial Radio Access
Network

UMTS Network Elements
• UMTS network architecture consists of three
domains:
• Core Network (CN): To provide switching,
routing and transit for user traﬃc.
• UTRAN : UMTS Terrestrial Radio Access
Provides the air interface access method for
User Equipment .
• User Equipment (UE): Terminals work as air
interface counterpart for Node B.The various
identities are: IMSI, TMSI, MSISDN, IMEI.


•
•

•
•
RAN :
BSS ( Base Station Subsystem) : For access
to existing GSM Network. It includes
BTS
BSC
UTRAN ( Universal Terrestrial Radio Access
Network): For access to UMTS (3G) services.
It includes
Node- B : Equivalent to BTS
RNC ( Radio Network Controller ) :
Equivalent to BSC in 2G system.


•
•
•
•

•
•
•
Core Network :
Circuit-switched core Network(CSCN) : It
includes elements that support circuit switched
connections which are
MSC Server
GMSC Server
Media Gateway
IWF –Inter working function
Packet-switched core network(PSCN):
Includes elements that support packet
switching technology.
SGSN
GGSN
BG ( Border Gateway )

•
•
•
•
•
Common Core Network elements: Common
Core Network elements are elements used by
both the CSCN and PSCN. Common elements
include:
HLR
VLR
AUC
EIR
SMS- MSC

GSM Network Components

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