Global System for Mobile Communications 2G overview

1. GSM OVERVIEW
Others ….
MSC
BTS
BSC
BTS PSTN
BTS
ISDN
SS#7
M
S
M
S
M
S
M
S
M
S
M
S

2. Mobile
Station
Base
Transceiver
Station
Base
Station
Controller
Mobile Service
Switching
Center
Visitor
Location
Register
Home
Location
Register
Authenticati
on Center
Equipment
Identity

15. GMSC
User
HLR
MSC
VLR
Directory
Number
Routing
Number
Routing
Number
Directory
Number
GMSC handling of a domestic call
GMSC

16. ÑÒNH NGHÓA CAÙC SOÁ VAØ NHAÄN DAÏNG TRONG HEÄ
THOÁNG GSM
Soá ISDN cuûa traïm di ñoäng MSISDN
MSISDN = CC+ NDC+ SN
Soá löu ñoäng cuûa maùy di ñoäng MSRN(Mobile Station Roaming
Number).
MSRN = CC + NDC + SN
Nhaän daïng thueâ bao di ñoäng quoác teá IMSI (International Mobile
Subscriber identity)
IMSI = MCC + MNC + MSIN.
Nhaän daïng thueâ bao di ñoäng taïm thôøi TMSI (Temporary Mobile
Subscriber Identity)
Nhaän daïng thieát bò cuûa traïm di ñoäng quoác teá IMEI
(International Mobile Equipment Identity)
IMEI = TAC + FAC + SNR + SP
Nhaän daïng vuøng ñònh vò LAI (Location Area Identity)
LAI = MCC + MNC + LAC
Nhaän daïng oâ toaøn caàu (CGI) (Cell Global Identity)
CGI = MCC + MNC + LAC + CI
Maõ nhaän daïng traïm goác (BSIC) (Base Station Identity Code)

17. Authentication & Encryption

18. Authentication & Encryption

19. Radio
Subsystem
RPE-LTP
encoder
RPE-LTP
decoder
13 bit
uniform to 8
bit A-Law
8 bit A-Law
to 13 bit
uniform
MSC
PSTN
/
ISDN
104 kbps
13 kbps
8000 samples/s
13-bit uniform
code
Analogue
speech
8000 samples/s
13-bit uniform
code
8000 samples/s
8-bit A-Law
ITU-T G.711, G.712,
G.713, G.714
RPE-LTP
encoder
RPE-LTP
decoder
13 bit
uniform to
Analogue
O/P
Analogue
to 13 bit
uniform
I/P
104 kbps 64 kbps
13 kbps
System Description

20. Radio Access
& Demod
GMSK
De-
Interleaving
Forward
Error
Coding
Interleaving
Radio Access
& Mod
GMSK
Interleaving
Forward
Error
Coding
Error
Correction
Radio Access
& Mod
GMSK
Error
Correction
De-
Interleaving
Radio Access
& Demod
GMSK
Dup Dup
Encoded speech
456 bits/frame 20ms
Encoded speech
456 bits/frame 20ms
22.8kbps 22.8kbps
13 kbps 13 kbps
System Description

22. Signalling in GSM network
O
A
M
L
A
P
D
BTS
MTP2
SCCP
MTP3
L
A
P
D
O
A
M
R
R
D
T
A
P
B
S
S
M
A
P
BSSAP
BSC
MTP1
MTP3
MTP2
SCCP
MTP2
MTP3
SCCP
BSSAP
DTAP/
BSSMAP
T
C
A
P
MM
CM M
A
P
NSS
R
R
MM
CM
MS
Um
Interface
A bis
Interface
A
Interface

23. GSM Specification
Access method TDMA/FDMA
Frequency band (MS to BS) 890 - 915 MHz
Frequency band (BS to MS) 935 - 960 MHz
Channel bandwidth 200 kHz
Modulation GMSK
Bit rate 270.833 kbps
Filter BT = 0.3 (Gaussian)
Voice channel coding RPE-LPC Convolutional 13 kbps
Frequency Hopping Slow hopping (217 hops/s)

24. THANK YOU