[2024]Digital Global Overview Report 2024 Meltwater.pdf
Gsm architecture
1.
2. 1. Network Subsystem includes the equipments
and functions related to end-to-end call.
2. Radio Subsystem includes the equipments and
functions related to the management of the
connections on the radio path.
3. Operations and Maintenance subsystem
includes the operation and maintenance of
GSM equipment for the radio and network
interface.
2
10. Voice and data transmission
Frequency and time synchronization
Monitoring of power and signal quality
of the surrounding cells
Provision of location updates even
during inactive state
Equalization of multi path distortions
10
11. Portable, vehicle mounted, hand held
MS identified by unique IMEI
Shall display at least last ten received,
dialed and missed calls
Minimum talk time of 1hr 30 min. and
standby time of 80 hrs
160 characters long SMS
11
15. Mobile Subscriber’s ISDN Number
The MSISDN is registered in the telephone
directory and used by the calling party for
dialing.
15
CC NDC SN
1 to 3 digits Variable Variable
MSISDN : not more than 15 digits
N(S)N
16. International mobile subscriber’s Identity
The IMSI is an unique identity which is
used internationally and used within
the network to identify the mobile
subscribers.
The IMSI is stored on the subscriber
identity module (SIM), the HLR, VLR
and AC database.
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17. 17
MCC MNC MSIN
3 digits 3 digits Not more than 9 digits
NMSI
IMSI : Not more than 15 digits
18. Temporary Mobile subscriber’s
Identity
The TMSI is an identity which guarantees
the integrity of the mobile subscribers on
the radio interface.
The VLR assigns a TMSI to each mobile
subscribers entering the VLR area.
18
20. International Mobile Equipment Identity
The IMEI is an unique code allocated
to each mobile equipment. It is
checked in the EIR.
IMEI check
White List
Grey List
Black List
20
22. Encodes, encrypts, multiplexes,
modulates and feeds the RF signals to
the antenna
Transcoding and rate adaption
Functionality
Time and frequency synchronization
signals transmission.
11 power classes from .01 watts
(Micro cell) to 320 watts (Umbrella
cell)
22
23. Frequency hopping
Random access detection
Uplink radio channel measurements
BTS mainly consists of a set of
transceivers (TRX). Can accommodate
1 to 7 TRX per Sector
23
24. It is connected to BTS and offloads MSC
Radio resource management
Inter-cell handover
Reallocation of frequencies
Power control
24
25. Time delay measurement of the received
signals from MS with respect to BTS
clock.
Performs traffic concentration to reduce
the number of lines from BSC to MSC.
Provide interface TCP/IP X.25 to the OMS
25
26. BSC performs call processing
TRAU are generally located at the site of MSC.
BSC- BTS configurations as per requirement.
Data from OMC and can be down loaded to
BSC
26
27. 27
BTS
BTS
BTS
BTS BTS
BTS
A-bis
BSC
BSS
Configuration -6
Multi - cell site
= multi--BTS
site
Many single
cell sites
BSS
MSC
BTS
A
A
A
Single - cell site
Configuration -1
Multi - cell site (sector Cells
Configuration -5
MCC: Mobile Switching Centre
BSS: Base Station System
BSC: Base Station Controller
BTS: Base Transceiver Station
A-bis
29. Manages communication between GSM &
other network
Call setup functions, basic switching are
done
MSC takes into account the RR allocation in
addition to normal exchange functions
MSC does gateway function while its
customers roams to other network by using
HLR /VLR
29
30. Paging, specifically call handling
Location updation
Handover management
Billing for all subscribers based in its area
Reallocation of frequencies to BTSs in its
area to meet heavy demands
30
31. Echo canceller operation control
Signaling interface to databases like HLR, VLR.
Gateway to SMS between SMS centers and
subscribers
Handle interworking function while working as
GMSC
31
32. It controls those mobiles roaming in its area.
VLR reduces the number of queries to HLR
One VLR may be incharge of one or more LA.
VLR is updated by HLR on entry of MS its area.
VLR assigns TMSI which keeps on changing.
IMSI detach and attach operation
32
33. IMSI & TMSI
MSISDN
MSRN.
Location Area
Supplementary service parameters
MS category
Authentication Key
33
34. Reference store for subscriber’s parameters,
numbers, authentication & Encryption values.
Current subscriber status and associated VLR.
Both VLR and HLR can be implemented in the
same equipment in an MSC.
one PLMN may contain one or several HLR.
34
35. Permanent data in HLR
Data stored is changed only by man-machine.
IMSI, MS-ISDN number.
Category of MS ( whether pay phone or not )
Roaming restriction ( allowed or not ).
Supplementary services like call forwarding
35
36. Temporary data in HLR
The data changes from call to call & is
dynamic
MSRN
RAND /SRES and Kc
VLR address , MSC address.
Messages waiting data used for SMS
36
37. AUC is a separate entity and physically
included in HLR
Protect against intruders in air interface
Authentication (Ki) and ciphering (Kc) key are
stored in this data base.
Keys change randomly with each call
Keys are never transmitted to MS on air Only
calculated response are sent.
37
39. This data base stores IMEI for all registered
mobile equipments and is unique to every ME.
Only one EIR per PLMN.
White list : IMEI, assigned to valid ME.
Black list : IMEI reported stolen
Gray list : IMEI having problems like faulty
software, wrong make of equipment etc.
39
40. 40
The centralized operation of the various
units in the system and functions needed to
maintain the subsystems.
Dynamic monitoring and controlling of the
network
Separate OMC-S and OMC-R for NSS and
RSS
Operations and Maintenance
Centre OMC
41. 41
functions
-O&M data function
-Configuration management
--Fault report and alarm handling
-Performance supervision/management
-Storage of system software and data
-Support GUI for operation and
Maintenance
Functions Of OMC
