Overview of Location Area Code - Cell ID (LAC-CI) in a GSM network (definition and the purpose).

1. Introducing to LAC-CI
By Riswan

2. Do you know what LAC-CI is?

3. 3
Unique
LAC-CI is a
in a Mobile Network
Ident it y

4. LAC-CI is Part of Cell Global Identity (CGI)
CGI
MCC
MNC
LAC
CI
3 digit
2 or 3
digit
5 digit
5 digit
CGI is a unique global identity for a Cell in the world

5. CGI Consist of MCC, MNC, LAC, & CI
MCC
MCC (Mobile
Country Code) is
represent the
country.
Indonesia : 510
Malaysia
: 502
Singapore : 525

6. CGI Consist of MCC, MNC, LAC, & CI
MCC
MNC
MCC (Mobile
Country Code) is
represent the
country.
MNC (Mobile
Network Code) is
represent the
Mobile Operator.
Indonesia : 510
Telkomsel : 10
Malaysia
XL
: 11
Indosat
: 01
: 502
Singapore : 525

7. 10
08
27
11
28
09
07
01
89
99
Mobile Operators in Indonesia and their MNC

8. CGI Consist of MCC, MNC, LAC, & CI
MCC
MNC
MCC (Mobile
Country Code) is
represent the
country.
MNC (Mobile
Network Code) is
represent the
Mobile Operator.
Indonesia : 510
Telkomsel : 10
Malaysia
XL
: 11
Indosat
: 01
: 502
Singapore : 525
Combination between MCC & MNC
will be used to identify a mobile
operator uniquely in the world.

9. Beside in CGI, MCC & MNC also Used in IMSI
(International Mobile Subscriber Identity)
IMSI
MCC
510
MNC
10
MSIN*
5411234567
*MSIN = Mobile Subscriber Identity Number

10. CGI Consist of MCC, MNC, LAC, & CI
MCC
MNC
MCC (Mobile
Country Code) is
represent the
country.
MNC (Mobile
Network Code) is
represent the
Mobile Operator.
Indonesia : 510
Telkomsel : 10
Malaysia
XL
: 11
Indosat
: 01
: 502
Singapore : 525
LAC
LAC (Location Area
Code) is represent a
serving area in a
GSM network.

11. LAC=239
LAC=128
LAC=123
LAC=124
LAC=127
LAC=234
LAC=126
LAC=125
LAC=238
LAC=235
LAC=236
Usually, LAC is Defined Based on Geographical Area.
LAC=237

12. CGI Consist of MCC, MNC, LAC, & CI
MCC
MNC
MCC (Mobile
Country Code) is
represent the
country.
MNC (Mobile
Network Code) is
represent the
Mobile Operator.
Indonesia : 510
Telkomsel : 10
Malaysia
XL
: 11
Indosat
: 01
: 502
Singapore : 525
LAC
CI
LAC (Location Area
Code) is represent a
serving area in a
GSM network.
CI (Cell ID) is
represent a radio
network element in
a mobile operator.

13. 1 CI
1 CI
1 CI
Totally, there are 3 CIs in this BTS
Physically,
a CI (Cell ID)
is configured
as an ID of a
BTS antenna.

14. This is Sample of a CGI in Telkomsel GSM Network

15. Various Shape of Cell Coverage Area

16. The Hexagon Coverage is shaped by building a BTS
with 3 sectors (antenna) at each corner of
the hexagon. Each antenna has 60° beamwidth.
2
3
1
3
2
1

17. The Circle Coverage is shaped by building a BTS
with 1 sector (antenna) at each center of the circle.
Each antenna has 360° beamwidth.
1
1

18. The Quadrangle Coverage is shaped by building
a BTS with 4 sectors (antenna) at each corner
of the quandrangle. Each antenna has 90° beamwidth.
2
2
3
1
3
4
1
4

19. Various Type of BTS Tower ………

20. Why We Need to Configure LAC-CI in Our
Network Properly ?

21. 1
As Prerequisite of a Mobile Call Establishment.
The Configuring Activity is Part of New BTS Deployment.
son
mother

22. Basic Call Establishment Flow in GSM
HLR
BSC 1
1
BSC A
MSC A
MSC B
VLR A
VLR B
LAC = 456,
CI = 789
BSC 2
Subscriber A
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
LAC = 123,
CI = 788
LAC = 123
CI = 787
MSISDN B = 0811XXXXX
IMSI = XYZ

23. Basic Call Establishment Flow in GSM
HLR
BSC 1
2
1
BSC A
MSC A
MSC B
VLR A
VLR B
LAC = 456,
CI = 789
BSC 2
Subscriber A
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
2 MSC A ask what the IMSI and the
current serving MSC of MSISDN B to
HLR.
LAC = 123,
CI = 788
LAC = 123
CI = 787
MSISDN B = 0811XXXXX
IMSI = XYZ

24. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
1
BSC A
MSC A
MSC B
VLR A
VLR B
LAC = 456,
CI = 789
BSC 2
Subscriber A
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
2 MSC A ask what the IMSI and the
current serving MSC of MSISDN B to
HLR.
LAC = 123,
CI = 788
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
information of it’s current serving MSC (MSC B)
LAC = 123
CI = 787
MSISDN B = 0811XXXXX
IMSI = XYZ

25. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
1
BSC A
MSC A
MSC B
LAC = 456,
CI = 789
BSC 2
4
Subscriber A
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
2 MSC A ask what the IMSI and the
VLR A
VLR B
current serving MSC of MSISDN B to
HLR.
LAC = 123,
CI = 788
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
information of it’s current serving MSC (MSC B)
4 MSC B send the IMSI XYZ to it’s VLR to asking the current LAC
that serving the MSISDN B.
LAC = 123
CI = 787
MSISDN B = 0811XXXXX
IMSI = XYZ

26. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
1
BSC A
MSC A
5
1 Subscriber A Dial MSISDN of Subscriber B
2 MSC A ask what the IMSI and the
BSC 2
4
Subscriber A
(0811XXXXX)
MSC B
LAC = 456,
CI = 789
VLR A
VLR B
current serving MSC of MSISDN B to
HLR.
LAC = 123,
CI = 788
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
information of it’s current serving MSC (MSC B)
4 MSC B send the IMSI XYZ to it’s VLR to asking the current LAC
that serving the MSISDN B.
5 VLR B answer by sending the serving LAC (LAC=123) to MSC B.
LAC = 123
CI = 787
MSISDN B = 0811XXXXX
IMSI = XYZ

27. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
LAC = 456,
CI = 789
6
1
BSC A
MSC A
MSC B
4
Subscriber A
5
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
2 MSC A ask what the IMSI and the
BSC 2
VLR A
VLR B
current serving MSC of MSISDN B to
HLR.
LAC = 123,
CI = 788
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
information of it’s current serving MSC (MSC B)
4 MSC B send the IMSI XYZ to it’s VLR to asking the current LAC
that serving the MSISDN B.
5 VLR B answer by sending the serving LAC (LAC=123) to MSC B.
6 MSC B order BSC with LAC=123 to send paging command to all cell with LAC=123
LAC = 123
CI = 787
MSISDN B = 0811XXXXX
IMSI = XYZ

28. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
LAC = 456,
CI = 789
6
1
BSC A
MSC A
MSC B
4
Subscriber A
2 MSC A ask what the IMSI and the
7
5
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
BSC 2
VLR A
VLR B
current serving MSC of MSISDN B to
HLR.
LAC = 123,
CI = 788
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
information of it’s current serving MSC (MSC B)
4 MSC B send the IMSI XYZ to it’s VLR to asking the current LAC
that serving the MSISDN B.
5 VLR B answer by sending the serving LAC (LAC=123) to MSC B.
6 MSC B order BSC with LAC=123 to send paging command to all cell with LAC=123
7 Order all cell with LAC=123 to broadcast paging.
LAC = 123
CI = 787
MSISDN B = 0811XXXXX
IMSI = XYZ

29. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
LAC = 456,
CI = 789
6
1
BSC A
MSC A
MSC B
4
Subscriber A
2 MSC A ask what the IMSI and the
7
5
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
BSC 2
VLR A
IMSI XYZ
VLR B
LAC = 123,
CI = 788
current serving MSC of MSISDN B to
HLR.
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
6 MSC B order BSC with LAC=123 to send paging command to all cell with LAC=123
IMSI XYZ
IMSI XYZ
information of it’s current serving MSC (MSC B)
4 MSC B send the IMSI XYZ to it’s VLR to asking the current LAC
that serving the MSISDN B.
5 VLR B answer by sending the serving LAC (LAC=123) to MSC B.
8
IMSI XYZ
8
IMSI XYZ
LAC = 123
CI = 787
IMSI XYZ
7 Order all cell with LAC=123 to broadcast paging.
8 All cell with LAC=123 broadcast paging with key information is IMSI = XYZ to all MSISDN in it’s coverage.
MSISDN B = 0811XXXXX
IMSI = XYZ

30. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
LAC = 456,
CI = 789
6
1
BSC A
MSC A
MSC B
4
Subscriber A
2 MSC A ask what the IMSI and the
7
5
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
BSC 2
VLR A
IMSI XYZ
VLR B
LAC = 123,
CI = 788
current serving MSC of MSISDN B to
HLR.
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
6 MSC B order BSC with LAC=123 to send paging command to all cell with LAC=123
IMSI XYZ
IMSI XYZ
information of it’s current serving MSC (MSC B)
4 MSC B send the IMSI XYZ to it’s VLR to asking the current LAC
that serving the MSISDN B.
5 VLR B answer by sending the serving LAC (LAC=123) to MSC B.
8
IMSI XYZ
8
IMSI XYZ
LAC = 123
CI = 787
9
IMSI XYZ
7 Order all cell with LAC=123 to broadcast paging.
8 All cell with LAC=123 broadcast paging with key information is IMSI = XYZ to all MSISDN in it’s coverage.
MSISDN B = 0811XXXXX
IMSI = XYZ
9 MSISDN B (IMSI=XYZ ) that served by LAC=123 CI=787 receive the paging signal and then ringing, then answer the call, and the call established.

31. Basic Call Establishment Flow in GSM
3
HLR
BSC 1
2
LAC = 456,
CI = 789
6
1
BSC A
MSC A
MSC B
4
Subscriber A
2 MSC A ask what the IMSI and the
7
5
1 Subscriber A Dial MSISDN of Subscriber B
(0811XXXXX)
BSC 2
VLR A
IMSI XYZ
VLR B
LAC = 123,
CI = 788
current serving MSC of MSISDN B to
HLR.
3 HLR send the IMSI of the IMSISDN B (IMSI=XZY) and also the
6 MSC B order BSC with LAC=123 to send paging command to all cell with LAC=123
IMSI XYZ
IMSI XYZ
information of it’s current serving MSC (MSC B)
4 MSC B send the IMSI XYZ to it’s VLR to asking the current LAC
that serving the MSISDN B.
5 VLR B answer by sending the serving LAC (LAC=123) to MSC B.
8
IMSI XYZ
8
IMSI XYZ
LAC = 123
CI = 787
9
IMSI XYZ
7 Order all cell with LAC=123 to broadcast paging.
8 All cell with LAC=123 broadcast paging with key information is IMSI = XYZ to all MSISDN in it’s coverage.
MSISDN B = 0811XXXXX
IMSI = XYZ
9 MSISDN B (IMSI=XYZ ) that served by LAC=123 CI=787 receive the paging signal and then ringing, then answer the call, and the call established.

32. 2
To Provision Various of
Mobile Services Properly

33. Sample of The Impact of Invalid LAC-CI Configuration
to a Mobile Services : Subscriber Charged with Wrong Tariff
12345-54321
Core
Network
VAS
Network
Billing
System
Billing System
Table of Tariff Zone
12345-54321 Aceh
Physically, LAC-CI = 12345-54321 is located in Jakarta.
But in the Billing System it’s configured in Aceh (it’s a
wrong configuration).

34. Sample of The Impact of Invalid LAC-CI Configuration
to a Mobile Services : Subscriber Charged with Wrong Tariff
12345-54321
Subscriber A
Core
Network
VAS
Network
Billing
System
Billing System
Table of Tariff Zone
12345-54321 Aceh
Subscriber B
When Subscriber A (in Jakarta and serving by LAC-CI =
12345-54321) call subscriber B (in Jakarta), the call
could be charged with wrong tariff, because Billing
System recognizes LAC-CI = 12345-54321 is in Aceh.

35. 3
To be Used as Data by Many Kinds of
Operation & Business Support Systems

36. Many of Operation & Business Support Systems use LAC-CI
as data source and reference data in their systems. If the configuration
of LAC-CI across the network elements is not done properly, the
information that produced by OSBSS will not valid too.
Operation
Performance
Reporting &
Analysis
Corporate
Performance
Dashboard
Asset
Management
System
Fault
Management
System
Business
Performance
Reporting &
Analysis
Configuration
Management
System

37. THANK YOU. Hopefully
this is useful for you.
In Indonesia We say it :
“TERIMA KASIH. Semoga
bermanfa’at.