Gsm Network
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Communication Engineering Eng.Mohyee Mikhemar Ain Shams University Aug 2002
Contents
Introduction
Cellular concepts
GSM network
GSM protocol
Circuit Realization
GSM Network
Mohyee Mikhemar 2002
2
GSM Network
Features:
Roaming. ISDN capability. Use of SIM card. Control of transmission power. Frequency hopping. Discontinuous transmission. Mobile-assisted handover
GSM Network
Mohyee Mikhemar 2002
3
GSM Architecture Operation and Maintenance subsystem OMS Switching Subsystem MS
BSS
Mobile Station GSM Network
SS Base Station subsystem
Mohyee Mikhemar 2002
4
Mobile Station
Mobile Equipment
Handset Identity code (32 bit).
SIM card: Subscriber Identity Module
IMSI: International Mobile Subscriber Identity (34 bit). Ki: Identity and Authentication key Kc: Ciphering key A3 , A5 , A8: Ciphering Algorithms
GSM Network
Mohyee Mikhemar 2002
5
Base Station Subsystem
BTS: Base Transceiver station
3 Antennas: 2 Rx & 1 Tx. Microwave link with the network
BSC: Base station controller
Control many (BTS) It handles many functions:
GSM Network
Channel Allocation Link quality Supervision
Mohyee Mikhemar 2002
6
Base Station Subsystem
Transmission of broadcast messages
Controlling power level
Controlling frequency hopping
Error correction coding and decoding
Hardware processing
Data and signaling encryption
Digital speech transcoding
Data rate adaptation
GSM Network
Mohyee Mikhemar 2002
7
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
MSC:Mobile Service Switching center Co-ordinates call setup One MSC control several BSC
GSM Network
Mohyee Mikhemar 2002
8
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
HLR:Home Location Register
Database of all subscribers information
GSM Network
Mohyee Mikhemar 2002
9
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
AUC:Authentication center
Manage the security data for subscriber authentication
GSM Network
Mohyee Mikhemar 2002
10
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
EIR:Equipment Identity Register
Database of all Mobile Equipments
GSM Network
Mohyee Mikhemar 2002
11
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
VLR:Home Location Register
Database of all visitors information
GSM Network
Mohyee Mikhemar 2002
12
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
GMSC:Gateway MSC
Gateway to the PSTN
GSM Network
Mohyee Mikhemar 2002
13
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
GIWU:Gateway Networking Unit
For Communication with users outside GSM
GSM Network
Mohyee Mikhemar 2002
14
OMS
Operation and Maintenance Subsystem:
Network operation and maintenance
Subscription management: charging and billing.
Mobile equipment management
GSM Network
Mohyee Mikhemar 2002
15
Spectrum Sharing
GSM Network
Mohyee Mikhemar 2002
16
FDD f↓ ⇒ Att.↓ MS
BS
BS
Atteunation α f
Uplink 890
MS Downlink
915
935
960
MHz
Total Band=25 MHz GSM Network
Mohyee Mikhemar 2002
17
FDM 124 Carrier 200KHz apart Ch1 F=890M+100k Ch2 F=890M+300k Ch124 F=915M-100k
890
915 Uplink
GSM Network
935 960 Downlink
Mohyee Mikhemar 2002
MHz
18
FDM 124 Carrier 200KHz apart Ch1 Guard Band F=890 M +100k Channel Spacing 100 KHz Ch2 200 KHz M k F=890 +300
Ch124 F=915M-100k
890
915 Uplink
GSM Network
935 960 Downlink
Mohyee Mikhemar 2002
MHz
19
FDM 124 Carrier 200KHz apart Ch1(up) F=890M+100k
890
915 Uplink
GSM Network
Ch1(Down) F=935M+100k
935 960 Downlink
Mohyee Mikhemar 2002
MHz
20
TDMA
Every channel is shared among 8 users
There are 124 Carriers each shared among 8 users.
A User is assigned a certain time slot on a certain carrier (Cn,TSk)
GSM Network
Mohyee Mikhemar 2002
21
(Cn,TSk) Frame
C0
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
C1
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
C123
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
f GSM Network
Mohyee Mikhemar 2002
22
(Cn,TSk)
C12
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
( C12,TS2 )
GSM Network
Mohyee Mikhemar 2002
23
Channels Space (Copy Right) C1
C0
C2
f
C3
TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7
1
2
3
GSM Network
4
5
6
7
8
9 10 11 12 13 14 15 16
Mohyee Mikhemar 2002
Frame No 24
Channels
Physical Channel:
It’s a time slot on any carrier (Cn,TSk).
Logical Chaneel:
It’s a channel mapped on a physical channel to do a certain job
GSM Network
Mohyee Mikhemar 2002
25
Channel Types
Traffic Channels (TCH)
Used after call setup for transmission of speech.
Control Chaneels (CCH)
Over head channels used for network administration and SMS.
GSM Network
Mohyee Mikhemar 2002
26
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
27
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
28
Control Channels
Broadcast Channels
(FCCH): Frequency Correction Channel
(SCH): Synchronization Channel
No Data just pure carrier Broadcast Mobile Network Identity Code Broadcast Base Station Identity Code Broadcast Current frame number
(BCCH): Broadcast Control Channel
GSM Network
Broadcast location area Identity Broadcast maximum output power Broadcast C0 of neighboring cells
Mohyee Mikhemar 2002
29
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
30
Control Channels
Common Control Channels
(PCH): Paging Control Channel
(RACH): Random Access Channel
Declare a coming call Used to initiate a call Used to respond to a paging
(AGCH): Access Grant Channel
GSM Network
Used to assign a dedicated channel for further communication
Mohyee Mikhemar 2002
31
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
32
Control Channels
Dedicated Channels
(SDCCH): Stand alone dedicated control Channel
(SACCH): Slow Associated control Channel
Call setup procedure SMS (↓) Setup power level and time advance (↑) Inform the BS about received power level
(FACCH): Fast Associated control Channel
GSM Network
Stolen for urgent hardover
Mohyee Mikhemar 2002
33
Burst
It’s the information contained in one time slot
1 time slot = 0.577 m.sec.
I frame = 8 time slots = 4.615 m.sec.
GSM Network
Mohyee Mikhemar 2002
34
Mapping C1
C0 F
C2
S
f
C3 B
B
B
B
C
C
C
C
F
S
C
C
C
C
D0 D0 D0 D0 D1 D1 D1 D1 D2 D2 D2 D2 D3 D3 D3 D3 T T T T T T S T T Broadcast Common Synchronizat Frequency Channel ionT T T Control T T T T T T T T T T S T T Correction Channel Channel
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
T
T
T
T
T
T
GSM Network
Mohyee Mikhemar 2002
T
Frame No 35
Mapping C1
C0 F
C2
S
f
C3 B
B
B
B
C
C
C
C
F
S
C
C
C
C
D0 D0 D0 D0 D1 D1 D1 D1 D2 D2 D2 D2 D3 D3 D3 D3 T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
Stand T T alone T T T Control T T T Channel T T S T T T Slow Associated Control T T T T T T T T T T T S T T T Channel T T Traffic T T T Channel T T T T T T S T T T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
T
GSM Network
Mohyee Mikhemar 2002
Frame No 36
Traffic Multiframe (26 Frames) 12 Traffic bursts
12 Traffic bursts
TTTTTTTTTTTTSTTTTTTTTTTTT I
Idle: • Reserved for future use
Slow Associated: • Power Control • Time Advance
It’s repeated on C0, TS2-7 and all TS’s on all other carriers GSM Network
Mohyee Mikhemar 2002
37
Control Multiframe (51 frames) C0, TS0: 10 bursts
10 bursts
10 bursts
F SBBBBCCCCF SCCCCCCCCF SCCCCCCCC
10 bursts
10 bursts
Idle
F SCCCCCCCC F SCCCCCCCC I
GSM Network
Mohyee Mikhemar 2002
38
Control Multiframe (51 frames) C0, TS1: 48 bursts
3 bursts
Idle
D0 D1 D2 D3 D4 D5 D6 D7 S0 S1 S2 S3 I 48 bursts
3 bursts
Idle
D0 D1 D2 D3 D4 D5 D6 D7 S4 S5 S6 S7 I
D:Stand alone (Call setup – SMS ) S:Slow Associated (Power Level-Time Advance) GSM Network
Mohyee Mikhemar 2002
39
TDMA Frame Structure
1 time slot = 15/26 m.sec
1 frame = 8 time slots = 120/26 m.sec.
1 traffic multiframe= 26 frame= 120 m.sec
1 Control multiframe= 51 frame= 235 m.sec
1 Super frame= 51 traffic=26 Control = 1326 frames = 6.12 sec
1 hyperframe= 2048 superframe = 3 hours 28 minutes 53.76 sec GSM Network
Mohyee Mikhemar 2002
40
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst
GSM Network
Mohyee Mikhemar 2002
41
Bust Types
Normal burst
Frequency correction burst Synchronization burst
Flag
Access burst
3 Tail Bits
57
1
Encrypte d bits
GSM Network
Guard interv al
26
1
57
3 8.25
Training Sequenc e Mohyee Mikhemar 2002
42
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst 3
142
3 8.25 All Zero Pattern
Tail Bits GSM Network
Guard interv al
Mohyee Mikhemar 2002
43
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst 3
Tail Bits
39
64
Encrypte d bits
GSM Network
Guard interv al
39
3 8.25
Training Sequenc e Mohyee Mikhemar 2002
44
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst 8
Tail Bits
41 Training Sequenc e
GSM Network
36
Guard interv al 3
68.25
Encrypte d bits
Mohyee Mikhemar 2002
45
Notes C0 is called the beacon and is transmitted with the maximum available power in the cell. There is a 3 time slots time shift between the uplink and the downlink, this simplify the circuits and enable using one TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 antenna and a duplexer.
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 GSM Network
Mohyee Mikhemar 2002
46
Contents
Introduction
Cellular concepts
GSM network
GSM protocol
Circuit Realization
GSM Network
Mohyee Mikhemar 2002
2
GSM Network
Features:
Roaming. ISDN capability. Use of SIM card. Control of transmission power. Frequency hopping. Discontinuous transmission. Mobile-assisted handover
GSM Network
Mohyee Mikhemar 2002
3
GSM Architecture Operation and Maintenance subsystem OMS Switching Subsystem MS
BSS
Mobile Station GSM Network
SS Base Station subsystem
Mohyee Mikhemar 2002
4
Mobile Station
Mobile Equipment
Handset Identity code (32 bit).
SIM card: Subscriber Identity Module
IMSI: International Mobile Subscriber Identity (34 bit). Ki: Identity and Authentication key Kc: Ciphering key A3 , A5 , A8: Ciphering Algorithms
GSM Network
Mohyee Mikhemar 2002
5
Base Station Subsystem
BTS: Base Transceiver station
3 Antennas: 2 Rx & 1 Tx. Microwave link with the network
BSC: Base station controller
Control many (BTS) It handles many functions:
GSM Network
Channel Allocation Link quality Supervision
Mohyee Mikhemar 2002
6
Base Station Subsystem
Transmission of broadcast messages
Controlling power level
Controlling frequency hopping
Error correction coding and decoding
Hardware processing
Data and signaling encryption
Digital speech transcoding
Data rate adaptation
GSM Network
Mohyee Mikhemar 2002
7
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
MSC:Mobile Service Switching center Co-ordinates call setup One MSC control several BSC
GSM Network
Mohyee Mikhemar 2002
8
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
HLR:Home Location Register
Database of all subscribers information
GSM Network
Mohyee Mikhemar 2002
9
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
AUC:Authentication center
Manage the security data for subscriber authentication
GSM Network
Mohyee Mikhemar 2002
10
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
EIR:Equipment Identity Register
Database of all Mobile Equipments
GSM Network
Mohyee Mikhemar 2002
11
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
VLR:Home Location Register
Database of all visitors information
GSM Network
Mohyee Mikhemar 2002
12
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
GMSC:Gateway MSC
Gateway to the PSTN
GSM Network
Mohyee Mikhemar 2002
13
Switching Subsystem EIR
AUC HLR
GMSC
MSC GIWU
VLR
GIWU:Gateway Networking Unit
For Communication with users outside GSM
GSM Network
Mohyee Mikhemar 2002
14
OMS
Operation and Maintenance Subsystem:
Network operation and maintenance
Subscription management: charging and billing.
Mobile equipment management
GSM Network
Mohyee Mikhemar 2002
15
Spectrum Sharing
GSM Network
Mohyee Mikhemar 2002
16
FDD f↓ ⇒ Att.↓ MS
BS
BS
Atteunation α f
Uplink 890
MS Downlink
915
935
960
MHz
Total Band=25 MHz GSM Network
Mohyee Mikhemar 2002
17
FDM 124 Carrier 200KHz apart Ch1 F=890M+100k Ch2 F=890M+300k Ch124 F=915M-100k
890
915 Uplink
GSM Network
935 960 Downlink
Mohyee Mikhemar 2002
MHz
18
FDM 124 Carrier 200KHz apart Ch1 Guard Band F=890 M +100k Channel Spacing 100 KHz Ch2 200 KHz M k F=890 +300
Ch124 F=915M-100k
890
915 Uplink
GSM Network
935 960 Downlink
Mohyee Mikhemar 2002
MHz
19
FDM 124 Carrier 200KHz apart Ch1(up) F=890M+100k
890
915 Uplink
GSM Network
Ch1(Down) F=935M+100k
935 960 Downlink
Mohyee Mikhemar 2002
MHz
20
TDMA
Every channel is shared among 8 users
There are 124 Carriers each shared among 8 users.
A User is assigned a certain time slot on a certain carrier (Cn,TSk)
GSM Network
Mohyee Mikhemar 2002
21
(Cn,TSk) Frame
C0
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
C1
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
C123
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
f GSM Network
Mohyee Mikhemar 2002
22
(Cn,TSk)
C12
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2
t
( C12,TS2 )
GSM Network
Mohyee Mikhemar 2002
23
Channels Space (Copy Right) C1
C0
C2
f
C3
TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS0 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS1 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS2 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS3 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS4 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS5 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS6 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7 TS7
1
2
3
GSM Network
4
5
6
7
8
9 10 11 12 13 14 15 16
Mohyee Mikhemar 2002
Frame No 24
Channels
Physical Channel:
It’s a time slot on any carrier (Cn,TSk).
Logical Chaneel:
It’s a channel mapped on a physical channel to do a certain job
GSM Network
Mohyee Mikhemar 2002
25
Channel Types
Traffic Channels (TCH)
Used after call setup for transmission of speech.
Control Chaneels (CCH)
Over head channels used for network administration and SMS.
GSM Network
Mohyee Mikhemar 2002
26
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
27
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
28
Control Channels
Broadcast Channels
(FCCH): Frequency Correction Channel
(SCH): Synchronization Channel
No Data just pure carrier Broadcast Mobile Network Identity Code Broadcast Base Station Identity Code Broadcast Current frame number
(BCCH): Broadcast Control Channel
GSM Network
Broadcast location area Identity Broadcast maximum output power Broadcast C0 of neighboring cells
Mohyee Mikhemar 2002
29
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
30
Control Channels
Common Control Channels
(PCH): Paging Control Channel
(RACH): Random Access Channel
Declare a coming call Used to initiate a call Used to respond to a paging
(AGCH): Access Grant Channel
GSM Network
Used to assign a dedicated channel for further communication
Mohyee Mikhemar 2002
31
Control Channels
Broadcast Channels
Common Control Channels
Dedicated Channels
GSM Network
Mohyee Mikhemar 2002
32
Control Channels
Dedicated Channels
(SDCCH): Stand alone dedicated control Channel
(SACCH): Slow Associated control Channel
Call setup procedure SMS (↓) Setup power level and time advance (↑) Inform the BS about received power level
(FACCH): Fast Associated control Channel
GSM Network
Stolen for urgent hardover
Mohyee Mikhemar 2002
33
Burst
It’s the information contained in one time slot
1 time slot = 0.577 m.sec.
I frame = 8 time slots = 4.615 m.sec.
GSM Network
Mohyee Mikhemar 2002
34
Mapping C1
C0 F
C2
S
f
C3 B
B
B
B
C
C
C
C
F
S
C
C
C
C
D0 D0 D0 D0 D1 D1 D1 D1 D2 D2 D2 D2 D3 D3 D3 D3 T T T T T T S T T Broadcast Common Synchronizat Frequency Channel ionT T T Control T T T T T T T T T T S T T Correction Channel Channel
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
T
T
T
T
T
T
GSM Network
Mohyee Mikhemar 2002
T
Frame No 35
Mapping C1
C0 F
C2
S
f
C3 B
B
B
B
C
C
C
C
F
S
C
C
C
C
D0 D0 D0 D0 D1 D1 D1 D1 D2 D2 D2 D2 D3 D3 D3 D3 T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
Stand T T alone T T T Control T T T Channel T T S T T T Slow Associated Control T T T T T T T T T T T S T T T Channel T T Traffic T T T Channel T T T T T T S T T T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
S
T
T
T
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
T
GSM Network
Mohyee Mikhemar 2002
Frame No 36
Traffic Multiframe (26 Frames) 12 Traffic bursts
12 Traffic bursts
TTTTTTTTTTTTSTTTTTTTTTTTT I
Idle: • Reserved for future use
Slow Associated: • Power Control • Time Advance
It’s repeated on C0, TS2-7 and all TS’s on all other carriers GSM Network
Mohyee Mikhemar 2002
37
Control Multiframe (51 frames) C0, TS0: 10 bursts
10 bursts
10 bursts
F SBBBBCCCCF SCCCCCCCCF SCCCCCCCC
10 bursts
10 bursts
Idle
F SCCCCCCCC F SCCCCCCCC I
GSM Network
Mohyee Mikhemar 2002
38
Control Multiframe (51 frames) C0, TS1: 48 bursts
3 bursts
Idle
D0 D1 D2 D3 D4 D5 D6 D7 S0 S1 S2 S3 I 48 bursts
3 bursts
Idle
D0 D1 D2 D3 D4 D5 D6 D7 S4 S5 S6 S7 I
D:Stand alone (Call setup – SMS ) S:Slow Associated (Power Level-Time Advance) GSM Network
Mohyee Mikhemar 2002
39
TDMA Frame Structure
1 time slot = 15/26 m.sec
1 frame = 8 time slots = 120/26 m.sec.
1 traffic multiframe= 26 frame= 120 m.sec
1 Control multiframe= 51 frame= 235 m.sec
1 Super frame= 51 traffic=26 Control = 1326 frames = 6.12 sec
1 hyperframe= 2048 superframe = 3 hours 28 minutes 53.76 sec GSM Network
Mohyee Mikhemar 2002
40
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst
GSM Network
Mohyee Mikhemar 2002
41
Bust Types
Normal burst
Frequency correction burst Synchronization burst
Flag
Access burst
3 Tail Bits
57
1
Encrypte d bits
GSM Network
Guard interv al
26
1
57
3 8.25
Training Sequenc e Mohyee Mikhemar 2002
42
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst 3
142
3 8.25 All Zero Pattern
Tail Bits GSM Network
Guard interv al
Mohyee Mikhemar 2002
43
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst 3
Tail Bits
39
64
Encrypte d bits
GSM Network
Guard interv al
39
3 8.25
Training Sequenc e Mohyee Mikhemar 2002
44
Bust Types
Normal burst
Frequency correction burst
Synchronization burst
Access burst 8
Tail Bits
41 Training Sequenc e
GSM Network
36
Guard interv al 3
68.25
Encrypte d bits
Mohyee Mikhemar 2002
45
Notes C0 is called the beacon and is transmitted with the maximum available power in the cell. There is a 3 time slots time shift between the uplink and the downlink, this simplify the circuits and enable using one TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 antenna and a duplexer.
TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 GSM Network
Mohyee Mikhemar 2002
46
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