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EGPRS Workshop(Agenda: Basics,planning & optimization,RG-10 feature descriptions)
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TIME DAY-1 (15- March) DAY-2(16- March) DAY-3(17- March) DAY-4(18- March)
9.30-11.00Introduction toGPRS/EGRS
Network AuditIntroduction toGPRS/EGRS
Network Audit,Capacity Audit
11.15 - 12.45 Configuration/ ParameterAssessments
Capacity AuditConfiguration/
ParameterAssessments
Optimization
12.45 - 13.30 LUNCH LUNCHLUNCH LUNCH
13.30 – 14.30Configuration/
ParameterAssessments
OptimizationConfiguration/
ParameterAssessments
Optimizationwith TrailResults
14.30 – 15.30Planning and
Network Audit OptimizationPlanning and
Network Audit
Optimizationwith Trail
Results
Workshop – Time Schedule
Beginners Intermediate
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Objectives
At the end of the course participants will be able to
• Understand the Architecture, Protocols, Interfaces of the DATA Network End toEnd.
• Understand the Process of DATA Planning & Optimization.
• Perform Network Assessment End to End.
• Use BSS counters and KPIs in Daily Work
• Perform Basic Optimization Tasks
• Know which features can be used in Optimization Process
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Content
• Introduction
– GMSK and 8PSK modulation – EGPRS Link Adaptation and incremental Redundancy (IR)
– State, mobility, session and radio resource management
• Dimensioning and planning
– Network Analysis and planning inputs
–Deployment planning
– Air Interface capacity planning (CDEF, CDED)
– Connectivity capacity planning (BTS, EDAP, PCU, Gb, SGSN)
• Optimization
– Configuration and feature assessment
–
BSS (KPI) and E2E performance assessment – Signaling capacity & resource allocation improvement
– Data rate optimization Connectivity capacity (BTS, EDAP, PCU, Gb, SGSN)
RTSL data rate improvement and Multislot usage maximization (BSS)
– Mobility improvement
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• Network Architecture & Interfaces - Modulation and Link Adaptation
• Protocols & Layers
•
Air –
Interface, RLC Mappings
• (E)GPRS Resource Allocation
• Territory Method
• Cell selection and re-selection
• Air interface - Modulation and Link Adaptation
• GPRS Coding Schemes (CS)
• EGPRS Modulation and Coding Schemes (MCS)
• GMSK and 8PSK
• EGPRS Link Adaptation and incremental Redundancy (IR)
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6 © Nokia Siemens Networks Presentation / Author / Date
(E)GPRS Optimization –Network Element and Configuration Assessment
BSC
GGSN
IP/MPLS/IPoATM -
Applicatio
n Servers
(co -
located
2G
SGSNBTS
HLR/
AC/ EIR
TCSM
TC
MSC/VLR
Abis Gb
BSC
BSC
GGSNGGSN
-backbone
Application
Servers
2G
SGSN
2G
SGSNBTS
HLR/
AC/ EIR
HLR/
AC/ EIR
TCSM
TC
MSC/VLR
GnGi
Gs
RF interface
• Coverage
•C/I
• Capacity
• Traffic volume
• Mobility
MS/Client
parameters
•
GPRS/EDGEcapability andrelease
•Multislot support
Abis interface
• EDAP size /
dimensioning
• # of E1/T1s
• GPRS/EDGE
traffic
Gb interface
• Bearer size
• IP v.s. FR
• Dimensioning
BTS
• GPRS territory
• BTS HWconsiderations
(TRX & BB-card)
• BTS SW (EPCR)
BSS
• PCU variant &
dimensioning
• PCU strategy in
mixed
configuration
• BSS SW and
features
SGSN
• Unit capacity
(PAPU etc.)
• BSS Gb Flow
control
RF
Server
• load
• settings (Linux/Win)
HLR
• QoS profile
• GPRS settings
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V2
(E) GPRS Functionality
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Functionality - Content
Introduction
• Network Architecture and Interfaces• Mobile Classes• Network Protocols
• Multiframe and Header Structure• Air Interface Mapping – Physical and Logical Channel
Procedures• State and Mobility Management
• GPRS Attach/Detach• Routing Area
•
Session Management (PDP context)• Temporary Block Flow
•RLC/MAC Header•TBF Establishment
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Module objectives
After completing this module, the participant should be able to:
• Explain the (E)GPRS main procedures: Mobilitymanagement, PDP context, Temporary Block Flow
• Describe the air interface principles: 8PSK modulation,Channel Modulation and Coding Schemes, Link Adaptation,Resource Allocation, Cell Selection/Re-selection processes
• List the principles of EDAP interface
• Explain the PCU main functionality
• Describe the Gb interface main structure
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BSC
BTS
•Class C Packet only
(or manually switched between GPRS and speech modes)
• Class B Packet and Speech (not at same time)
(Automatically switches between GPRS and speech modes)
• Class A Packet and Speech at the same time(DTM is subset of class A)
(E)GPRS Mobile Terminal Classes
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(E)GPRS Multislot Classes
Type 1
Multislot Classes 1-12- Max 4 DL or 4 UL TSL (not at same time)- Up to 5 TSL shared between UL and DL- Minimum 1 TSL for F Change- 2-4 TSL F Change used when idle
measurements required
Multislot Classes 19-29- Max 8 downlink or 8 uplink
(not required at same time)- 0-3 TSL F Change
Multislot Classes 30-45 (Rel-5)- Max 5 downlink or 5 uplink (6 shared)- Max 6 downlink or 6 uplink (7 shared)
Type 2
Multislot Classes 13-18- simultaneous receive & transmit- max 8 downlink and 8 uplink(Not available yet, difficult RF design)
DL
UL
DL
UL
1 TSL for F Change
1 TSL for Measurement
DL
UL
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MSCHLR/AuCEIR
BSCBTS
Um
PSTNNetwork
GSM & (E)GPRS Network Architecture
PCU
EDAPGb
GatewayGPRSSupportNode(GGSN)
ChargingGateway (CG)
LocalAreaNetwork
Serve
rRouter
Corporate 1
Server
Router
Corporate 2
Datanetwork(Internet)
Datanetwork
(Internet)
Billing System
Inter-PLMNnetwork
GPRSINFRASTRUCTURE
BorderGateway(BG)
LawfulInterceptionGateway (LIG)
GPRSbackbonenetwork(IPbased)
ServingGPRSSupportNode(SGSN)
SS7Network
PAPU
DomainNameServer(DNS)
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(E)GPRS Network Elements and Primary Functions
SGSN
• Mobility Management
• Session Management
• MS Authentication
• Ciphering
• Interaction with
VLR/HLR
• Charging and statistics• GTP tunnelling to
other GSNs
GGSN• GTP tunnelling to
other GSNs• Secure interfacesto externalnetworks
• Charging &statistics
• IP addressmanagement
Charging Gateway• CDR consolidation• Forwarding CDR
information tobilling center
Border Gateway• Interconnects different
GPRS operators'backbones
• Enables GPRS
roaming
• Standard Nokia IProuter family
Domain Name Server• Translates IP host names to IP
addresses• Makes IP network configuration
easier• In GPRS backbone SGSN uses
DNS to get GGSN and SGSN IPaddresses
•
Two DNS servers in the backboneto provide redundancy
Legal Interception Gateway• Enables authorities to intercept
subscriber data and signaling• Chasing criminal activity• Operator personnel has very
limited access to LI functionality• LI is required when launching the
GPRS service
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GSM and (E)GPRS Interfaces
Gf
D
Gi
C
E
Gp
Gs
Signaling and Data Transfer InterfaceSignaling Interface
MSC/VLRTE BSS
TEPDN
R Um
Gr
HLR
Other PLMN
GGSN
Gd
SM-SCSMS-GMSC
SMS-IWMSC
EIR
GnLAN SW
/ IP BB
DNS CG LIG
Gn Gn
Gc
A
Gb
MT
SGSN SGSN GGSN
Gn
Gn Gn
Optional
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EGPRS Implementation
• Can be introduced incrementally to the network where the demand is
• EGPRS capable MS
• Network HW readiness/upgrade (BTS and TRX)
• TRS capacity upgrade (Abis and Gb!)
• Dynamic Abis
GMSK coverage
8-PSK coverage
AA-bis
Gb
Gn
BTS
BTS
BSC
SGSNGGSN
MSC
More capacity ininterfacesto support higher datausage
EDGE capableTRX,GSMcompatible
EDGEcapableterminal,
GSMcompatible
EDGEfunctionality in
the networkelements
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(E)GPRS Protocol Architecture
These following figures shows the
different protocols between thedifferent network elements of a(E)GPRS networks. As it can beseen, the BSS network relatedprotocols are the physical (L1/RF)and RLC/MAC layers. The
RLC/MAC, LLC and SNDCP layersare (E)GPRS specific layers, but thehigher layers are applicationdependent.
Appln. layer
EGPRS Spec layer
Data Blocks segmentation betweenprotocols
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SNDCP (Subnetwork Dependent ConvergenceProtocol) Layer
• Multiplexer/demultiplexer for different networklayer entities onto LLC layer
• Compression of protocol control information(e.g. TCP/IP header)
• Compression of data content (if used)
• Segmentation/de-segmentation of data to/fromLLC layerLLC
SNDCP
IP
TCP/UDP
APP
RLC
MAC
GSM RF
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Logical Link Control (LLC) Layer
LLC
SNDCP
IP
TCP/UDP
APP
RLC
MAC
GSM RF
•
Reliable logical connection between SGSN and•Independent of underlying radio interface protoc
ControlAddress
FCSInformation
LLC Frame
1 1-3 1-1520 3 Octets
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LLC Reliability – HLR QoS Profile
• In practice only reliability classes 2
and 3 work today properly from theend user satisfaction perspective andcan thus be commercially used.
• There are some terminals in themarket that can not support the usageof reliability class 2.
Resulting R99 Attribute Derived from R97/98Attribute
Name Value
Value Name
SDU error ratio
10-6 1, 2
Reliability class10-4 3
10-3 4, 5
Residual bit error ratio
10-5 1, 2, 3, 4
Reliability class4*10-
3 5
Delivery of erroneousSDUs
'no' 1, 2, 3, 4
Reliability class'yes' 5
SDU error ratio:<= 5*10-4 RLC ack> 5*10-4 RLC unack
Radio Link Control (RLC)/ Medium Access Control
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Radio Link Control (RLC)/ Medium Access Control(MAC) Layers
RLC• Achieves reliable transmission of data across air interface
• Segmentation/de-segmentation of data from/to LLC layer
MAC•
Control of MS access to common air-interface medium• Flagging of PDTCH/PACCH occupancy
LLC
SNDCP
IP
TCP/UDP
APP
RLC
MAC
GSM RF
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Downlink RLC Data Block with MAC Header
USF - Uplink State Flag
TFI - Temporary FlowIndicator
BSN - BlockSequence Number
FBI - Final Block Indicat
Uplink RLC Data Block with MAC Header
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Uplink RLC Data Block with MAC Header
TFI - Temporary Flow
Indicator = TBF ID.
BSN - BlockSequence Number=RLC block ID within
TBF
TLLI - TemporaryLogical LinkIdentifier = type ofmobile ID
Countdown value -used to calculatenumber of RLCblocks remaining
GSM RF Layer
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GSM RF Layer
• Modulation/demodulation
• Bit inter-leaving
• TDMA frame formatting
• Cell selection/re-selection
• Tx power control
• Discontinuous reception (DRx)
LLC
SNDCP
IP
TCP/UDP
APP
RLC
MAC
GSM RF
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(E)GPRS Protocol Architecture – Mapping to RFlayer
• LLC frames aresegmented into
RLC Data Blocks
• In the RLC/MAClayer, a selectiveARQ protocolprovidesretransmission oferroneous RLCData Blocks
• When a complete
LLC frame issuccessfullytransferred acrossthe RLC layer, it isforwarded to theLLC layer.
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Bursts on the Air Interface – Mapping RLC blocks
1 TDMA frame = 4.615 ms= BURST PERIOD
RLC/MAC Blocks
TDMA Bursts
RLC Blocks
4 x TDMA Frames = 4 Bursts = 1 Radio block = 18.46 ms = 1-2 RLC block(s)
Note: Amount of RLCblocks per radio blockdepends on used
(modulation) codingscheme (M)CS
0 70 70 70 7
12 x RLC/MAC Blocks = 1 x 52 PDCH MultiFrame = 240 ms
12 RLC/MAC Blocks / 0.240 s = 50 RLC/MAC Blocks / s
0 1 2 3 4 5 6 7 8 9 10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
B0(0..3) B1(4..7) B2 (8..11)PTCCH
B3(13..16) B4(17..20) B5(21..24)IDLE
B6(26..29) B7(30..33) B8(34..37)PTCCH
B9(39..42) B10(43..46) B11(47..50)IDLE
52 TDMA Frames (240 ms)
GSM and (E)GPRS Multiframe
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GSM and (E)GPRS Multiframe
TS 6FCCH
GSM Signalling GSM Traffic GPRS traffic
TDMA frameTS 0 TS 1 TS 2 TS 3 TS 4 TS 5 TS 7
SCH Radio Block 0
Radio block 1
FCCHRadio Block 2
SCH
Radio Block 3
Radio Block 4
FCCHSCH
Radio Block 5
Radio Block 6
FCCHSCH Radio Block 7
Radio Block 8
FCCHSCH
Radio Block 9
Radio Block 10
Radio Block 11
IDLE
PCH+AGCH
PCH+AGCH
BCCH
PCH+AGCH
PCH+
AGCH
PCH+AGCH
PTCCH
PTCCH
IDLE
IDLE
0123456789
10111213141516171819202122232425262728293031323334
3536373839404142434445464748495051
SACCH
IDLE
TCH
TCH
TCH
TCH
TCH
TCH
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(E)GPRS Logical Channels
GPRS Air Interface Logical Channels
CCCH
Common Control Channels
DCH
Dedicated Channels
PCH
Paging CH
AGCH
Access Grant CH
RACH
Random Access CH
Existing GSM Signaling Channels(Shared with GPRS Signaling)
PACCHPacket Associated
Control CH
PDTCH
Packet Data TCH
NEW GPRS Signaling and Data
Channels
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Functionality - Content
Introduction
•
Network architecture and Interfaces• Mobile classes• Network Protocols
• Multiframe and header structure• Air interface mapping – physical and logical channel
Procedures• State and Mobility Management
• GPRS Attach/Detach• Routing Area
• Session Management (PDP context)• Temporary Block Flow
•RLC/MAC Header•TBF Establishment
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(E)GPRS Procedures - Content
• Mobility Management and State Management
• Mobile States
• GPRS attach
• GPRS detach
•
Routing Area• Session Management
• PDP context activation
• Temporary Block Flow
• RLC/MAC Header• TBF establishment
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GPRS Mobility Management - Mobile States
MS location not known,subscriber is notreachable by the GPRSnw.
IDLE
READY
STANDBY
READYTimerexpiry
MOBILEREACHABLETimer expiry
PacketTX/RX
GPRS
Attach/Detach
MS location known toRouting Area level.MS is capable to beingpaged for point-to-point data.
MS location known tocell level. MS istransmitting or has justbeen transmitting. MS iscapable of receivingpoint-to-point data.
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GPRS Mobility Management - Mobile States
• GPRS MM is based on States State Transition occurs when a pre-defined
transaction takes place GPRS Attach (/Detach)• MS makes itself known to the network
• The authentication is checked and the mobile location is updated
• Subscriber Information is downloaded from the HLR to the SGSN
• State transition Idle to Ready
• Normal procedure should occur within 5 seconds each• Mobility Management before Session Management:
• GPRS attach needs to happen before PDP context activation
• States controlled by timers
•
READY Timer• MOBILE REACHABLE Timer
• Timer values are configurable with SGSN Parameter Handling
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Attach Procedure
• The GPRS Attach procedure establishes a GMM context. This procedure
is used for the following two purposes:• a normal GPRS Attach, performed by the MS to attach the IMSI for GPRS
services only
• a combined GPRS Attach, performed by the MS to attach the IMSI forGPRS and non-GPRS services
• Attach procedure description
• MS initiates by sending Attach Request
• If network accepts Attach Request it sends Attach Accept
– P-TMSI, RAI
• If network does not accept Attach request it sends Attach Rejected
• MS responds for Attach Accept message with Attach Complete (only if P-TMSI changes)
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(E)GPRS Attach Process – Combined GPRS/IMSIAttach
1. Attach Request
2. Identification Request
2. Identification Response
3. Identity Request
3. Identity Response
4. Authentication
5. (IMEI Check - optional)
6a. Update Location
6b. Cancel Location
6c. Cancel Location Ack
6d. Insert Subscriber Data
6e. Insert Subscriber Data Ack
MS BSS new SGSN old SGSN GGSN HLREIRoldMSC/VLR
newMSC/VLR
(E)GPRS A h P C bi d GPRS IMSI
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(E)GPRS Attach Process – Combined GPRS/IMSIAttach
6f. Update Location Ack
7a. Location Update Request
7b. Update Location
7c. Cancel Location
7d. Cancel Loc. Ack
7e. Insert Subscriber Data
7f. Insert Subscriber Data Ack
7g. Update Location Ack7h. Location Update Accept
9. Attach Complete
8. Attach Accept
10. TMSI Reallocation Complete
MS BSS new SGSN old SGSN GGSN HLREIRoldMSC/VLR
newMSC/VLR
D h P
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Detach Process
• GPRS Detach procedure is used for the following two
purposes:• a normal GPRS Detach
• a combined GPRS Detach (GPRS/IMSI detach, MSoriginated)
• MS is detached either explicitly or implicitly:
• Explicit detach: The network or the MS explicitly requestsdetach.
• Implicit detach: The network detaches the MS, without
notifying the MS, a configuration-dependent time after themobile reachable timer expired, or after an irrecoverable radioerror causes disconnection of the logical link
(E)GPRS D h P
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(E)GPRS Detach Process
2. Delete PDP Context Request1. Detach Request
2. Delete PDP Context Response
3. IMSI Detach Indication
5. Detach Accept
MS BSS GGSNSGSN MSC/VLR
4. GPRS Detach Indication
Session Management - Establishing a PDP
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• PDP Context (Packet Data Protocol): Network level
information which is used to bind a mobile station (MS) tovarious PDP addresses and to unbind the mobile stationfrom these addresses after use
• PDP Context Activation• Gets an IP address from the network
•Initiated by the MS
• Contains QoS and routing information enabling data transfer between MS andGGSN
• PDP Context Activation and Deactivation should occur within 2 seconds
Session Management Establishing a PDPContext
PDP C t t A ti ti 1
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MSC
PSTNNetwork
GPRSINFRASTRUCT
URE
HLR/AuCEIR
GatewayGPRSSupportNode(GGSN)
DomainNameServer(DNS)
GPRSbackbonenetwork
(IPbased)
PDP Context Activation - 11. MS sends "Activate PDP Context Request" toSGSN
2. SGSN checks against HLR
Datanetwork(Internet)
Datanetwork
(Internet)
Access
Point
SS7Network
APN="Intranet.Ltd.com"
2.ServingGPRSSupportNode(SGSN)
Access Point Name = Reference to an external packet data network the user wants to connect to
BSCBTS
U
m
1.
PDP C t t A ti ti 2
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MSC
PSTNNetwork
GPRSINFRASTRUCT
URE
HLR/AuCEIR
PDP Context Activation - 2Finding the GGSN
3. SGSN gets the GGSN IP address from DNS4. SGSN sends "Create PDP Context Request" to
GGSN
Datanetwork(Internet)
Datanetwork
(Internet)
SS7Network
4.
ServingGPRSSupportNode(SGSN)
GPRSbackbonenetwork
(IPbased)
3.DomainNameServer(DNS)
GatewayGPRSSupportNode(GGSN)
Access
Point
BSCBTS
U
m
DNS (Domain Name System) = mechanism to map logical names to IP addresses
PDP C t t A ti ti 3
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MSC
GPRSINFRASTRUCT
URE
HLR/AuCEIR
PSTNNetwork
PDP Context Activation - 3Access Point Selection
Access Point Name refers to theexternal network the subscriber wantsto use
Datanetwork(Internet)
SS7Network
ServingGPRSSupportNode(SGSN)
GPRSbackbonenetwork
(IPbased)
DomainNameServer(DNS)
GatewayGPRSSupportNode(GGSN)
Access
Point APN="Intranet.Ltd.com"
Datanetwork
(Internet)
BSCBTS
U
m
PDP C t t A ti ti 4
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MSC
PSTNNetwork
GPRSINFRASTRUCT
URE
HLR/AuCEIR
Datanetwork(Internet)
Datanetwork
(Internet)
Access
Point APN="Intranet.Ltd.com"
DomainNameServer(DNS)
SS7Network
5.
ServingGPRSSupportNode(SGSN)
GPRSbackbonenetwork
(IPbased)
6.
GatewayGPRSSupportNode(GGSN)
BSCBTS
U
m
User (dynamic) IP address allocated5. GGSN sends "Create PDP Context Response" back
to SGSN6. SGSN sends “Activate PDP Context Accept“ to the
MS
PDP Context Activation - 4Context Activated
Temporary Block Flow
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Temporary Block Flow
Temporary Block Flow (TBF):
• Physical connection where multiple mobile stations can share one or more traffic channels –
each MS has own TFI• The traffic channel is dedicated to one mobile station at a time (one mobile station is
transmitting or receiving at a time)• Is a one-way session for packet data transfer between MS and BSC (PCU)• Uses either uplink or downlink but not both (except for associated signaling)• Can use one or more TSLs
Comparison with circuit-switched:• normally one connection uses both the uplink and the downlink timeslot(s) for traffic
In two-way data transfer:• uplink and downlink data are sent in separate TBFs - as below
BSC
Uplink TBF (+ PACCH for downlink TBF)
Downlink TBF (+ PACCH for uplink TBF)
PACCH (Packet Associated Control Channel): Similar to GSM CSW SACCH
TLLI / TBF Concept
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TLLI / TBF Concept
TBF (TFI + TSL)
MS SGSN GGSN
Internet orIntranet
GPRS CORE
BSS
TBF (RLC / MAC Flow)
TBF (LLC Flow)
PCUBTS
TLLI (GTP Flow)
P-TMSI
HLRVLR
IMSI
TMSI
Temporary Block Flow
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Temporary Block Flow
• DL TBF
• Network starts and releases TBFs
• FBI (Final Block Indicator) indicates the last block in a DL TBF
• UL TBF
• Close-ended: limited number of octets
• Open-ended: an arbitrary number of octets
• MS may request either close-ended or open-ended TBF
– NW decides the type in PACKET UPLINK ASSIGNMENT
•
MS can ask network to give more resources if needed
E t bli hi DL TBF d S di D t
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Establishing a DL TBF and Sending Data
Paging
UL TBF forMS location
Packet Control Ack (for TA)
Packet Polling
Packet Downlink Assignment
Data / Signalling
Ack / Nack
Packet Channel Request
Packet Paging Response (LLC Frame)
BTS
RACH
AGCH
PDTCH
PACCH
PACCH
PACCH
PCH
Immediate Assignment for UL TBF
Immediate Assignment for DL TBF
AGCH
PDTCH
PACCH
PACCH
Multiple Mobiles and Downlink Transmission
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Multiple Mobiles and Downlink Transmission
TFI2
TFI5
TFI3
TFI2 BTS
The TFI included in the Downlink RLC Blockheader indicates which Mobile will open the RLCBlock associated with its TBF
RLC Data Block
Establishing an UL TBF and Sending Data
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Establishing an UL TBF and Sending Data
Packet Channel Request
Immediate Assignment for UL TBF
UL Data
Signaling + Ack/Nack
Final UL Data
Final Ack/Nack
Packet control Ack
RACH
AGCH
PDTCH
PACCH
PDTCH
PACCH
PACCH
BTS
Multiple Mobiles and Uplink Transmission
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• Several mobiles can share one timeslot
• Maximum of 7 Mobiles are queued in the Uplink
• Mobile transmissions controlled by USF (Uplink State Flag) sent on DL(dynamic allocation)
TS 1
TS 2
TS 3
Uplink State Flag
• Mobile with correct USF will transmit in following Uplink block
• Timeslot selected to give maximum throughput
New MS
Multiple Mobiles and Uplink Transmission
Multiple Mobiles and Uplink Transmission
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Multiple Mobiles and Uplink Transmission
USF =1
USF =2
USF =3
USF = 3 BTS
RLC Data Block
The USF included in the Downlink RLC Block header
identifies which Mobile will transmit in the following UplinkRLC Block
Routing Area
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Routing Area
The Routing Area Update procedure is used for the followings:
• a normal Routing Area Update• a combined Routing Area Update
• a periodic Routing Area Update
• an IMSI Attach for non-GPRS services when the MS is IMSI-
attached for GPRS services.
• Routing Area (RA)
• Subset of one, and only one Location Area (LA)
• RA is served by only one SGSN
• For simplicity, the LA and RA can be the same
• Too big LA/RA increases the paging traffic, while too smallLA/RA increases the signaling for LA/RA Update
Routing Area
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Routing Area
LocationArea (LA)
RoutingArea (RA)
SGSN
MSC/VLR
GS Interface
• Bad LA/RA border design can significantly increase the
TRXSIG on LA/RA border cells causing the cell-reselectionoutage to be longer
• LA/RA border should be moved from those areas where thenormal CSW and PSW traffic is very high
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