1. Name:Shivalila A H,Shima
Name:Shivalila A H,Shima.R Sub:Wireless communication Sub Code:10EC81 Dept:Electronics and communication
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2. UNIT 4,5
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3. GSM and TDMA Technology
Objectives
Discuss the basic services offered by GSM cellular and the frequency bands of operation.
Discuss the network components of a GSM system and the basic functions of the mobile station, base station system, and network switching system.
Explain the concept of GSM network interfaces and protocols, and their relationship to the OSI model.
Explain the GSM channel concepts.
Discuss the functions of the GSM logical channels.
Explain the TDMA concept and how it is implemented in GSM.
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4. Objectives
Explain the GSM operations of call setup, location updating, and handover.
Discuss the GSM operations that occur over the Um interface.
Explain the mapping of logical channels on to the GSM physical channels.
Discuss the various GSM identities.
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5. Introduction to GSM and TDMA
GSM services
Teleservices: provide standard voice communications between two end users and additional communications between two end users applications according to some standard protocol
Bearer services : provide the user the ability to transmit data between user network interfaces
Supplementary services: that enhances or support a teleservice provided by the network
GSM radio frequency carriers
GSM 900 band has 124 carrier frequencies
GSM 1800 band has 374 carrier frequencies
GSM 1900 band has 299 carrier frequencies
Each carrier can be shared by eight users,so the total number of channels for each system will varies
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6. GSM Frequency bands and channel numbers
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7. Introduction to GSM and TDMA
GSM timeslots
For a particular carrier frequency a channel consists of a single timeslot that occurs during a TDMA frame of eight timeslots
Each GSM TDMA frame represents eight Physical channel
See Figure
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8. GSM Network and System Architecture
Mobile station
Is the device that provides the radio link between the GSM subscriber and the wireless mobile network.
Base station system: is the link between MS and the GSM mobile services MSC
Network switching system: provides the necessary interface for the connection of the wireless network(PSTN,PDN)
SMS gateway
Flexible numbering register
- Operation and support system and other nodes
. Administrative and control system
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10. GSM Network and System Architecture
GSM network interfaces and protocols
GSM interfaces
Abis interface
A interface
Um interface
Layered structure/OSI model
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11. GSM Network interfaces
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12. GSM Network and System Architecture
GSM protocols and signaling model
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13. MS communicates with the MSC to provide system connection ,mobility ,and radio resource management by sending messages back and forth over the air interface from the MS to BTS,between the BTS and the BSC ,and between the BSC and MSC.
Um interface :Layer protocol used on the Um interface is LAPDm(link access protocol-channel D) is a modified version of the ISDN protocol LAPD
The major differences between LAPD and LAPDm protocol are the ,for LAPDm no error detection is employed and are segmented into shorter messages than LAPD to be compatible with the TDMA frame length used in GSM.
Abis Interface : exists between the BSC and the BTS .The layer two protocol used is LAPD,at the layer 3 ,most messages just pass through the BTS transparently.The BTS management entities manage the radio resource management messages( involves Encryption).
A interface: exists between the BSC and the MSC,Signalling over A interface is done according to the base station signalling application part(BSSAP) using the network service part of SS7

14. BSSAP signaling is sent transparently through the TRC mode
Layer three is sub divided into three parts RR ,MM and CM]
The protocol used to transfer the CM and MM messages is BSSAP
BSSAP has two parts-Direct transfer application part (DTAP) & base station system
management application part (BSSAMP)
DTAP is used to send CM and MM messages between the MSC and the MS transparently through the BSS
BSSAMP is used to send messages between MSC & BSC
ATER interface-Only exist in GSM system that have separate units for the transcoder controller and the BSC
The signalling between the BSC and TRC is performed by the use of BSC/TRC application part(BTAP) protocol
BSSAP signaling is sent transparently through the TRC mode

15. MSC interface-The right hand protocol stack of the MSC corresponds to the
MSC network interfaces to the VLR ,HLR,GMSC,PSTN
MTP (message transfer part) is used to transport messages and for routing and addressing
Signalling connection control part (SCCP) adds function to SS7 signaling to provide more extensive addresssing and routing
MTP and SCCP together form the network service part
TCAP-Transfer capabilities application part & mobile application part are layer 7 protocol
TCAP provides services based on connection less network services
MAP is a protocol specifically designed for mobile communications. Is is used for signaling between databases
ISDN –user part (ISDN-UP) and temporary user part (TUP) are used between MSC & the ISDN /PSTN for call setup and supervision

16. GSM Channel Concept Time division multiple access Frames Multiframes
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17. GSM Channel Concept Logical channels - Broadcast channels
Broadcast control channel
Frequency correction channel
Synchronization channel
- Common control channels
Paging channel
Random access channel
Access grant channel
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18. GSM Channel Concept - Dedicated control channels - Speech processing
Stand-alone dedicated control channel
Slow associated control channel
Fast associated control channel
Cell broadcast channel
- Speech processing
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19. GSM Channel Concept Timeslots and TDMA frames TDMA frames
TDMA multiframes
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20. GSM Channel Concept Hyperframes Superframes Multiframes 26 frame
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21. GSM Channel Concept Timeslot bursts Normal burst
Frequency correction burst
Synchronization burst
Access burst
Dummy burst
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22. GSM Channel Concept Mapping of logical channels to physical channels
Multiplexing of GSM logical channels
Different schemes
Needed control signals
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23. GSM Channel Concept Mapping of logical channels to physical channels
Transmission of short messages
Traffic channels
Half-rate traffic channels
Paging groups
GSM Identities
Mobile station associated numbers
Network numbering plans
Mobile station roaming number
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24. MOBILE STATION ROAMING NUMBER (MSRN)
GSM CALL SETUP USING THE MSRN
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25. GSM System Operations (Traffic Cases)
Registration, call setup, and location updating
Call setup
Interrogation phase
Radio resource connection establishment
Service request
Authentication
GSM System Operations (Traffic Cases)
Call setup
Ciphering mode setting
IMEI check
TMSI reallocation
Call initiation procedure
Assignment of a traffic channel
Call confirmation, call accepted, and call release
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26. GSM System Operations (Traffic Cases)
Other aspects of call establishment
Location updating
Normal location updating (idle mode)
IMSI detach/attach location updating
Periodic location updating
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27. GSM Service request operations
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28. GSM System Operations (Traffic Cases)
Call handoff
Intra-BSC handover
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29. Inter-BSC handover
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30. GSM System Operations (Traffic Cases)
Call handoff
Inter-MSC handover
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31. GSM Infrastructure Communications (Um Interface)
Review of GSM protocol architecture
Service access points
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33. North American TDMA TIA/EIA-136 basics TIA/EIA-136 channel concept
TIA/EIA-136 timeslots and frame details
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