3G Protocol Stack
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Transcript of 3G Protocol Stack
3G – Protocol ArchitectureArchitecture
Amal Chandran
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC1
UMTS – Universal Mobile Telecom System
Inter-PLMN Backbone Network
3G-SGSN 3G-MSC
CS Domain3G-GGSN
PS Domain
Iu-CSIu-PS
Gs
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC2
Node B
RNC
UTRANIur
WCDMA
IubUu
GSM/WCDMA Network Architecture
3G/WCDMA
NAS
2G/GSM
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC3
SGSN – Serving GPRS Support NodeGGSN – Gateway GPRS Support NodeBSC – Base Station ControllerBTS – GSM Base Transceiver StationGERAN –GSM/EDGE Radio Access Network
MSC – Mobile Services Switching CentreGMSC – Gateway MSCHLR – Home Location RegisterRNC – Radio Network ControllerNode B – WCDMA Base StationUTRAN – UMTS Radio Access Network
Network Components
• Node – B (BTS) : Physical Layer Device
• RNC: Radio Network Controller
• Controls the Node-B’s
• MSC/GMSC: Mobile Switching Centre, Gateway MSC
• Circuit Switched Services• Circuit Switched Services
• VLR: Visitor Location Register
• Database of Active Users in the area
• HLR: Home Location Register
• Subscriber Information
• SGSN/GGSN: Serving GPRS Support Node, Gateway GSN
• Packet Switched Services
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC4
Protocol Stack – Review of Concepts
• Software Architecture for enabling Communication
• Each Layer has specific function
Layer 3 message
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC5
Layer 2 Header
L1 L1 L1
L1 = Layer 1 Header
101010101000010101000010101010111010110101010......
Spreading, Scrambling, Modulation…
Layer 1: The Physical Layer
• Connects Node-B to UE
• Cell Searching
• Spreading
• Scrambling
3G Network
• Scrambling
• Modulation
• Power Control
• Measurements
• Physical Channels of WCDMA
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC6
Layer 2: MAC
• Medium Access Control
• Provides Access to Layer 1.
• Priority Handling between the data flows of the UE
• Multiplexing of Logical Data (Logical Channels)• Multiplexing of Logical Data (Logical Channels)
• Traffic Volume Monitoring
• Identification of UE on common channels
• Ciphering of Voice Data
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC7
Layer 2: RLC
• Radio Link Control
• Segmentation and Re-Assembly of data
• In-sequence delivery
• Error detection and recovery• Error detection and recovery
• Flow control
• Ciphering of Control Data
• Three modes: Acknowledged, Unacknowledged, and Transparent
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC8
Layer 3: RRC – The Brain
• RRC : Radio Resource Control
• Management of Radio Resources
• Connection Management
• Setup, Maintenance, Release.
• Monitor the connection states
3G Network
• Monitor the connection states
• Transfer of control messages
• Called “Signalling Messages”
• Control of 3G measurements
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC9
Layer 3: Non Access Stratum
• Mobility Management
• Keeps track of Location Area
• Call Management
• Everything related to calls• Everything related to calls
• Session Management
• Data Connection management
• SMS Services
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC10
User Data
• PDCP
• Packet Data Convergence Protocol
• Header Compression
• BMC• BMC
• Broadcast and Multicast Control
• Broadcast of information – Like “Tsunami Warnings”,
“Traffic Alerts”
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC11
Powering up a mobile, in 3G
• Search for cells
• Find out the parameters of the cell from the information broadcast
• Identify the Network ID (PLMN ID) of the network
• Check the quality of the cell
• Cell is good? • Cell is good?
• Setup a connection
• Authenticate
• Update the network with UE’s location information
• Ready to go…
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC12
Incoming Call?
• Paging message
• UE’s ID is registered with the network now.
• Send out paging request to UE
• Identify the UE ID, and respond to the paging. • Identify the UE ID, and respond to the paging.
• Exchange call information –
• Codec to use, Quality (Data Rate) of the call etc.
• Setup the call
• Establish a dedicated connection
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC13
Change of Cells – Hand Over
• Current cell quality is low
• Move to another cell
• Simultaneous reception from two (or more) Node-Bs
• Soft Hand Over• Soft Hand Over
• Softer Handover
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC14
Soft/Softer handover
BTS 1
BTS 2
BTS 3
RNC 1
(SRNC)
RNC 2
(DRNC)
Call transferred �
Via SRNS relocation
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC15
Sector 1 Sector 2 Sector 3 Sector 4 Sector 5 Sector 6
Add Sector 2 : Softer Handover
Add Sector 3 : Soft Handover, same RNC
Add Sector 4, remove Sector 1
Add Sector 5, remove Sector 2
Add sector 6,
Remove sector 4,
Triggers SRNS relocation
remove Sector 3
Setup call
Overall Architecture
L3Non Access Stratum
User Data
CMSMS MM
SNDCP
SM
TCP/IP Data – User Data
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC16
L3
WCDMA
WCDMA MAC
WCDMA L1
RRC
WCDMA RLC
PDCP
GSM/GPRS
L1
L2
RR
GSM L2
GPRS MAC
GPRS LLC
GPRS RLC
GSM L1
Interested in Reading Further?
• Web:
• http://www.3gpp.org/
• Look for Specification number 25.301
• http://www.etsi.org/
• Print Media
• WCDMA For UMTS : Antti Toskala, Harri Holma
© 2008 Nokia 3G Protocol Stack.ppt / 2009-08-26 / AC17
Q & A ?
THANK YOU ☺☺☺☺
Q & A ?discussion.forum.nokia.com/vtuedusat
WCDMA_L1.ppt / 25-Aug-2009/ UDN18
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