evolium base station subsystem introduction to gprs and egprs
TRANSCRIPT
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 1
EVOLIUM Base Station SubsystemINTRODUCTION TO GPRS/EGPRS
© All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without
written authorization from Alcatel.
TRAINING MANUAL
3FL10472ACAAWBZZA2 – MARCH 2006
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 2
2Introduction to GPRS/EGPRS
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Safety WarningBoth lethal and dangerous voltages are present within the equipment. Do not wear conductive jewellery while working on the equipment. Always observe all safety precautions and do not work on the equipment alone.
CautionThe equipment used during this course is electrostatic sensitive. Please observe correct anti-static precautions.
Trade MarksAlcatel and MainStreet are trademarks of Alcatel.All other trademarks, service marks and logos (“Marks”) are the property of their respective holders including Alcatel. Users are not permitted to use these Marks without the prior consent of Alcatel or such third party owning the Mark. The absence of a Mark identifier is not a representation that a particular product or service name is not a Mark.
CopyrightThis document contains information that is proprietary to Alcatel and may be used for training purposes only. No other use or transmission of all or any part of this document is permitted without Alcatel’s written permission, and must include all copyright and other proprietary notices. No other use or transmission of all or any part of its contents may be used, copied, disclosed or conveyed to any party in any manner whatsoever without prior written permission from Alcatel.
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© 2004 Alcatel. All rights reserved.DisclaimerIn no event will Alcatel be liable for any direct, indirect, special, incidental or consequential damages, including lost profits, lost business or lost data, resulting from the use of or reliance upon the information, whether or not Alcatel has been advised of the possibility of such damages.Mention of non-Alcatel products or services is for information purposes only and constitutes neither an endorsement nor a recommendation.Please refer to technical practices supplied by Alcatel for current information concerning Alcatel equipment and its operation.
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 3
� 1 What is GPRS ? 6
� 1.1 Definition 8
� 1.2 General architecture 9
� 1.3 MS Class 10
� 1.4 MS Multislot Class 11
� 1.5 GPRS Main Concepts 12
� 1.6 The benefits of GPRS 17
� 1.7 EGPRS 18
� 1.8 Quality of service profile 19
� 1.9 Services 20
�
� 2 GPRS Operation 23
� 2.1 Main Entities 25
� 2.2 MS Mobility Management States 30
� 2.3 MS Radio Resource Operating Modes 31
� 2.4 Basic procedures 32
� 2.5 Charging 45
� 2.6 Security 47
� 3 The Base Station Subsystem 52
� 3.1 3GPP Position 54
� 3.2 Alcatel’s Choice 55
� 3.3 Layered Model 56
� 3.4 Gb Interface 58
� 3.5 Radio Interface 60
� 4 Alcatel Solution 71
� 4.1 GPRS Network Overview 73
� 4.2 Alcatel 9135 MFS 74
� 4.3 Packet Switched Core Network 80
� 4.4 GPRS Network Management 82
� 4.5 Alcatel QoS offer 83
� 5 Annex and Glossary 88
Contents
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 4
Self assessment of the objectives Contract number :
Course title :
Client (Company, centre) :
Language : English dates from : to :
Number of trainees : Location :
Surname, First name :
Did you meet the following objectives ?Tick the corresponding box
Please, return this sheet to the trainer at the end of the training
Instructional objectivesYes (orGlobally
yes)
No (orglobally
no)Comments
1 To be able to identify the benefits of GPRS
2 To be able to describe the organization of aGPRS network, architecture, interfaces andprotocols.
3 To be able to describe the main datainterchange mechanisms on a GPRSnetwork
4 To be able to characterize the solutionoffered by Alcatel
Other comments
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 5
Instructional objectivesYes (orGlobally
yes)
No (orglobally
no)Comments
Self assessment of the objectives (continued)
Thank you for your answers to this questionnaire
Other comments
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 6
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 7
7Introduction to GPRS/EGPRS
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1 What is GPRS ?Session presentation
> Objective: to be able to identify the technicaland commercial benefit of GPRS.
> Program:
• 1.1 Definition
• 1.2 General architecture
• 1.3 MS Class
• 1.4 MS Multislot Class
• 1.5 GPRS Main Concepts
• 1.6 GPRS Benefits
• 1.7 EGPRS
• 1.8 Quality of Service profile
• 1.9 Services
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 8
8Introduction to GPRS/EGPRS
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1 What is GPRS ?1.1 Definition
> Definition (3GPP TS 22.060)
• GPRS provides data transfer capabilities between a sending entity and one or more receiving entities.
• These entities may be an MS or a Terminal Equipment, the latter being attached either to a GPRS network or to an external data network.
• The base station provides radio channel access for MSs to the GPRS network.
▼ PDN (Packet Data Network)
� IP networks = Internet (connectionless)
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 9
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1 What is GPRS ?1.2 General architecture
GPRSCore Network
IPGb
NSSA PSTN
Gi
PDN IP / PPP
RADIOACCESSNETWORK
BSS
Packetswitching
circuitswitching
▼ GPRS Core Network
The GPRS Core Network is also called GSS (GPRS Sub-System). It is an IP network, and therefore contains routers (machines handling the packet switching function.)
▼ Routing Function
Data transmission between GPRS Support Node (GSN), may occur across external data networks that provide their own internal routing functions, for example X.25 [34], Frame Relay or ATM networks.
▼ IP interworking
The GPRS Core Network supports interworking with networks based on the Internet protocol (IP). The GPRS Core Network may provide compression of the TCP/IP header when an IP datagram is used within the context of a TCP connection.
▼ X.25
X.25 PDP Type have been removed from the standard sinc e R99.
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10Introduction to GPRS/EGPRS
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1 What is GPRS ?1.3 MS Class
> Class A
• Operates GPRS and other GSM services simultaneously.
> Class B
• Monitors control channels for GSM GPRS and other GSM services simultaneously,
• but can only operate one set of services at one time.
> Class C
• Exclusively operates GPRS services.
▼ Classes A and B
Require dual scanning by the mobile for both GSM and GPRS service requests. Class A or B mobiles are "attached" simultaneously to both networks.
▼ Class B
The exchange of packets is suspended to answer to an incoming GSM call (the GPRS subscriber is considered to be in the "busy" or “on hold" state).
The PDP contexts are still active on the SGSN side until the Purge_Timer elapses.
▼ Class C
Exclusively operates GPRS services.
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1 What is GPRS ? 1.4 MS multislot class
NAxx119 to 29like 10
000NA88218011NA77217121NA66216131NA55215131NA44214131NA33213121544112121534111121524110121523191215141813143317131423161314221513141314132322131323121224221111
TrbTraTtbSumTxRxTypeMulti-slotclass
▼ MS type
� Type 1 are simplex MS, i.e. without duplexer: they are not able to transmit and receive at the same time
� Type 2 are duplex MS, i.e. with duplexer: they are able to transmit and receive at the same time
▼ Rx
� Maximum number of received timeslots that the MS can use per TDMA frame. The receive TS shall be allocated within window of size Rx, but they need not be contiguous. For SIMPLEX MS, no transmit TS shall occur between receive TS within a TDMA frame. This does not take into account measurement window (Mx).
▼ Tx
� Maximum number of transmitted timeslots that the MS can use per TDMA frame. The transmit TS shall be allocated within window of size Tx, but they need not be contiguous. For SIMPLEX MS, no receive TS shall occur between transmit TS within a TDMA frame.
▼ SUM
� Maximum number of transmit and receive timeslot (without Mx) per TDMA frame
▼ Meaning of Ttb, Tra et Trb changes regarding MS type s.
� For SIMPLEX MS (type 1):
� Ttb Minimum time (in timeslot) necessary between Rx and Tx windows
� Tra Minimum time between the last Tx window and the first Rx window of next TDMA in order to be able to open a measurement window
� Trb same as Tra without opening a measurement window
� For DUPLEX MS (type 2):
� Ttb Minimum time necessary between 2 Tx windows belonging to different frames
� Tra Minimum time necessary between 2 Rx windows belonging to different frames in order to be able to open a measurement window
� Trb same as Tra without opening a measurement window
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 12
12Introduction to GPRS/EGPRS
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PDNPDNPDNPDN
PSPSPSPS
GSMGSMGSMGSM
networknetworknetworknetwork
CSCSCSCS
1 What is GPRS ?1.5 GPRS Main Concepts (1/5)
> Use of radio resources in case of circuit switching
Fixed Rate
Radio timeslot
Radio interface
Access nodeAccess nodeAccess nodeAccess node
CS <CS <CS <CS <---->PS>PS>PS>PS
▼ Drawbacks of CS for data services
� one radio channel at 9.6 kbit/s per user
� fixed bit rate => waste (in the case of discontinuous service) and limitation on bit rate
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13Introduction to GPRS/EGPRS
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GPRSGPRSGPRSGPRS
networknetworknetworknetwork
PSPSPSPS
PDNPDNPDNPDN
PSPSPSPS
1 What is GPRS ?1.5 GPRS Main Concepts (2/5)
> Use of radio resources in case of packet switching
Radio timeslot
Radio interface
Variable Rate
▼ Benefits of Packet Switching
� Variable bit rate becomes possible
� One MS uses several RTSs. The maximum number of RTSs is given by the Operator (O&M parameters) and MS capabilities (MS multislot class)
� One RTS is shared by several MSs. The maximum number of MSs per RTS is given by the Operator (O&M parameters) and 3GPP specifications (limitation due to addressing availability)
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1 What is GPRS ?1.5 GPRS Main Concepts (3/5)
> Radio resource assigned according to requirement
• Radio resource shared between users
• Various radio channel coding schemes are specified to allow bit rates from 9 to more than 150 kb/s per user (according also to the quality of radio transmission and the modulation used)
• High bit rates if several channels are assigned to one MS
• Low bit rates if one channel is shared by several MSs.
> Optimized use of the radio resource
• Use of the radio resources only when data is transferred
• Uplink and downlink resources reserved separately
▼ Radio resource sharing
The radio resources are shared by statistical multiplexing. As in GSM, no subscriber has their own permanent radio resource.
▼ Bit rate
Maximum instantaneous bit rate provides 171,2 kb/s by the allocation of eight RTSs to one subscriber. The stated maximum bit rates are different, because different coding schemes are used, which impacts the bit rate over a RTS. (see Annex)
▼ Up link (UL) and downlink (DL)
It is possible to use a different bit rates in each transmission direction, whereas in CS (Circuit Switching) mode, there is a maximum limit of 9.6 kb/s, in both directions and at all times.
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1 What is GPRS ?1.5 GPRS Main Concepts (4/5)
> Dynamic allocation and sharing of radio resources
User 1User 2User 3User 4User 5
1 RESOURCE SHARED BY X USERS (PDCH)
User 1
USER1 USES 3 RESOURCES (3 PDCH)
1 RESOURCE USED BY ONE USER NOT SHARED TCH
User 1
Number of resources according to the capability of the MS
▼ Caution: Animated slide that does not make sense if not in the slide-show mode.
▼ Optimized use
A radio resource (set of Radio Blocks over one or several RTS) is allocated only when data is being transferred, by establishing and releasing Temporary Block Flow (TBF), that can be presented as micro-connections, each time a data transfer has to be sent over the radio interface.
▼ Radio resource sharing
One TS can be shared by several MSs, by dynamic time multiplexing under control of the BSS.
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 16
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> Variable useful transmission rate per Radio resource
Maximum security
Channel Transmission rate about 22 k with GMSK about 60k with 8PSK (Edge)
minimum throughput
Minimum security
Maximum throughput
When the radio transmission has a good quality the security can be reduced in order to increase the useful transmission rate
1 What is GPRS ?1.5 GPRS Main Concepts (5/5)
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1 What is GPRS ?1.6 The benefits of GPRS
> GPRS benefits
• BSS hardware (included OMC-R) is re-used from GSM
• Smooth GPRS introduction
• Higher data throughput thanks to EGPRS (EDGE)
• Data transfers can billed by volume instead of time
• An MS can exchange data by GPRS in parallel with a conventional GSM call (if MS Class A)
▼ BSS is re-used
The same Radio Access Network is re-used, and a Packet Control Unit (PCU) function is implemented in the BSS.
▼ Compared to the GSM BSS
� same frequency bands
� same TDMA frame structure
� same burst structure
� same frequency hopping laws
� ...
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1 What is GPRS ?1.7 EGPRS
> EGPRS is an enhancement of GPRS
• allows higher bit rates on the radio interface
• achieved by using
– a new modulation (8-PSK)
– and new coding schemes (MCS-1 to MCS-9) in the MS and the BSS.
> The same set of services provided by GPRS is available in EGPRS.
▼ Shared = in other words: "the radio resources are shared by statistical multiplexing". As in GSM, no subscriber has their own permanent radio resource.
▼ High or low bit rates = more than one time slot per MS or conversely, more than MS on the same TS (one TDMA frame occupies 4.615 ms and is divided into 8 TS or channels).
▼ Maximum instantaneous bit rate provided = 171,2 kbps through the allocation of eight TSs to one subscriber. The stated maximum bit rates are different (according to the BSS release), because different ways of encoding the data, or "coding schemes", are used, which impacts the bit rate over a TS. (cf Annex)
▼ Optimized use:refer to Radio resource allocation in the slides to come + radio resource management in the BSS Chapter.The radio resource allocation is suitable for variable, bursty traffic (downloading Web pages).
▼ Up link (UL) and downlink (DL): It is possible to use a different bandwidth (bit rate) in each transmission direction, whereas in CS (circuit switching) mode, there is a maximum limit of 9,6 kbps, in both directions and at all times.
▼ QoS: Henceforth, QoS parameters are part of subscription data, according to the wide range of services provided to a subscriber.
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19Introduction to GPRS/EGPRS
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Precedence Classrelative importance of service under congestion3 classes
Delay Classtotal delay measured between R or S point and Gi4 classes
Reliability Classacknowledgement of packets5 classes
Peak throughput Class
Mean throughput Class
the maximum data rate allowed to the user
maximum data rate during a period
Throughput class
19 classes
9 classes
1 What is GPRS ?1.8 Quality of service profile
▼ Precedence class
According to the class, user data packet can be discarded during the transfer due to a congestion state.
3 classes are defined : any, normal, high
▼ Delay class
The delay class depends on the operator network because a measurement is done between the R or S interface (between the Mobile Terminal and the Terminal Equipment) and the Gi interface. For each operator, delay values are different so delay classes are a reference not a strict value.
4 classes are defined : best effort, 1, 2, 3
▼ Reliability class
The reliability means that user data packets are acknwoledged during the transfer. The reliability classes are defined according to the acknowledgement or not of the packet.
5 classes are defined
▼ Throughput class
The throughput class is defined by the 2 following parameters:
� Mean Throughput : 9 classes are defined (from best effort to 111 Kb/s)
� Peak Throughput : 19 classes are defined (from 8 Kb/s to 2048 Kb/s)
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1 What is GPRS ?1.9 Services
Always-on
Mobile OfficeMobile OfficeMobile OfficeMobile Office•Voice (!)•E-mail•Agenda• IntraNet/InterNet•Corporate Applications•Database Access
Vertical applicationVertical applicationVertical applicationVertical application•Traffic Management•Automation•Mobile branches •Health
Location servicesLocation servicesLocation servicesLocation services•Traffic Conditions• Itineraries•Nearest Restaurant, Cinema, Chemist, Parking;, ATM ...
FunFunFunFun•Games (Hangman, Poker, …)•Screen Saver•Ring Tone•Horoscope•Biorhythm
Media
TransportationTransportationTransportationTransportation•Flight/train Schedule• reservation
MusicMusicMusicMusic•Downloading ofmusic files orvideo clips
NewsNewsNewsNews(general/specific)(general/specific)(general/specific)(general/specific)• International/National News•Local News•Sport News•Weather•Lottery Results•Finance News…
DirectoriesDirectoriesDirectoriesDirectories•Yellow/White Pages• International Directories•Operator Services
M-commerce
PhysicalPhysicalPhysicalPhysical•on-line shopping•on-line food
Non physicalNon physicalNon physicalNon physical•on-line Banking•Ticketing•Auction•Gambling….
▼ Retrieval services
Provide the capability of accessing information stored in data base centers. The information is sent to the user on demand only. An example of one such service in the Internet's World Wide Web (WWW).
▼ Messaging services
Offer user-to-user communication between individual users via storage units with store-and-forward mailbox, and/or message handling (e.g., information editing, processing and conversion) functions;
▼ Conversational services
Provide bi-directional communication by means of real-time (no store-and-forward) end-to-end information transfer from user to user. An example of such a service is the Internet's Telnet application;
▼ Tele-action services
Characterized by low data-volume (short) transactions, for example credit card validations, lottery transactions, utility meter readings and electronic monitoring and surveillance systems.
▼ Distribution services
Characterized by the unidirectional flow of information from a given point in the network to other (multiple) locations. Examples may include news, weather and traffic reports, as well as product or service advertisements;
▼ Dispatching services
Characterized by the bi-directional flow of information from a given point in the network (dispatcher) and other (multiple) users. Examples include taxi and public utility fleet services;
▼ Conferencing services
Provide multi-directional communication by means of real-time (no store-and-forward) information transfer between multiple users.
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21Introduction to GPRS/EGPRS
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– True or False ?
– GPRS is a circuit switching technology
– The GSS is an IP network
– Data transfers are often conducted at variable bit rates
– With a class B mobile, a web page can be downloaded while speaking
– Billing by volume allows subscribers to be permanently on line
– Several channels can be assigned to a MS
– One channel is shared by several MSs
– EGPRS is GPRS with better Throughput
– The useful transmission rate depends on the radio quality
Time allowed :
5 minutes
1 What is GPRS ? Exercise
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 22
22Introduction to GPRS/EGPRS
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Thank you for answeringthe self-assessment
of the objectives sheet
1 What is GPRS ? Evaluation
> Objective : to be able to identify the technical and commercial benefit of GPRS
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 23
All rights reserved © 2004, Alcatel
2 GPRS Operation
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2 GPRS OperationSession presentation
> Objective: to be able to describe the organization of aGPRS network architecture, interfaces and protocols.
> Program:
• 2.1 Main Entities
• 2.2 MS Mobility Management States
• 2.3 MS Radio Resource Operating Modes
• 2.4 Basic Procedures
• 2.5 Charging
• 2.6 Security
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2 GPRS Operation2.1 Main Entities
> Overview
CELLS
BTS BSC
BSS RADIO ACCESS NSS CALL PROCESSING
circuits
To PSTN
GPRS
N7
AUC EIR
HLR
IP
SGSN
SGSN
NTP DNS
DHCP
To IP NetworksGGSN
BG To other operatorIP Networks
PCU includedin BSS
MSCVLR
▼ PCU functions
� LLC PDU segmentation / re-assembly into RLC/MAC PDU
� PDCH scheduling (resource multiplexing)
� Channel access control (access requests and grants)
� ARQ function (RLC block Ack / Nak, buffering and retransmission of RLC blocks)
� Radio channel management (power control, congestion control, broadcast control information).
▼ DNS (Domain Name Server) and DHCP (Dynamic Host Convergence Protocol)
▼ NTP server (Network Time Protocol) for GSN synchronization. In general an NTP application does not run on a dedicated server. The OMC-G can play this role.
▼ HLR (Home Location Register) is involved in MS attachment to the GPRS network (authentication + services subscribed to)
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GSS
2 GPRS Operation 2.1 Main Entities
> SGSN and GGSN
IPbackbone
GGSN1
IP network 1
IP network 1
GGSN2
IP network 1
GGSN3
IP network 1
IP network 1
SGSN1
SGSN2
SGSN5
SGSN3
SGSN4
▼ The SGSN (Serving GPRS Support Node) stores subscriber data:
� Subscription information
� IMSI
� one or more temporary identities (P-TMSI)
� zero or more PDP addresses
� Location information
� the cell or the RA where the MS is registered
� the VLR number of the associated VLR (if the Gs interface is implemented)
� the GGSN address of each GGSN for which an active PDP context exists
It also manages:
� the transfer and routing of user data packets from the GSS towards the BSS
� the mobility (GPRS attach/detach, data retrieval from the HLR, RA / Cell update)
� the authentication and encryption (Access control and security)
� the sessions (PDP context activation/deactivation)
� The transfer of charging data.
▼ The GGSN (Gateway GPRS Support Node) stores subscriber data received from the HLR and the SGSN:
� Subscription information
� IMSI
� zero or more PDP addresses
� Location information
� the SGSN address of the SGSN where the MS is registered
It also manages:
� the allocation and use of dynamic @IP for MS,
� the tunneling and encryption of user data at Gi interface,
� the transfer of user data packets,
� the charging data.
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2 GPRS Operation2.1 Main Entities
> Servers
GPRSBACKBONE
SGSN GGSN
NTP
DNS DHCPIP add
256.167.123.34
Alcatel.fr
▼ DNS
� Resolve a name into an IP address
� Use in Mobility procedure
▼ DHCP
� Provide dynamically IP addresses
� Split Users into pool of IP addresses
▼ NTP
� Provide one time reference for all the network
� Have a very precise time reference
� Synchronization from satellite
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MS
SGSNBSS VPLMNBG
VISITED PLMN
GGSN
2 GPRS Operation2.1 Main Entities
> Border gateway
INTER PLMN NETWORK
HPLMN GGSN PDNBG
HOME PLMN
▼ Border Gateway functions
� Inter-PLMN routing and forwarding of user packets (IP router)
� Security functions (firewall, access-list filtering)
▼ Connection of two Border Gateways
Via a private or public IP network, through the Gp interface.
▼ Choice of GGSN
If a subscriber wants to access an Intranet (PDN) in his home country, from the visited PLMN, the selected GGSN is the one from the home PLMN
For Internet access a GGSN in the visited country could be used.
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A
2 GPRS Operation2.1 Main Entities
Gn
Signaling + data
Signaling
Mobile GPRS
Gd
Um
GPRS network
Gb
BSS
Gc
GsGr
GiPDN
SGSN
SGSN GGSN
HLRMSCSMS-GMSC
> Interfaces
▼ Signaling protocols
� MAP/TCAP/SCCP/MTP on Gr, Gd and Gc,
� GTP/UDP/IP on Gn,
� BSSAP+/SCCP/MTP on Gs,
� GMM/SM/LLC on Gb/Um.
▼ Gc interface
Used for network-requested PDP contexts activation (GGSN asks the HLR for SGSN routing information).
▼ Gs interface
Defines the Network Mode of Operation I (NMOI). It allows to perform LA + RA combined Location Update, and PS and CS paging coordination (refer to ANNEX).
▼ Gr interface
Exchange of subscription information at GPRS attachment phase
▼ Additional interfaces
� Gf (to the EIR)
� Gd to deliver the SMS to the mobiles via the GPRS network (SGSN option and subscriber feature)
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2 GPRS Operation2.2 MS Mobility Management States
Idle
Ready
Stand-by
> MS MM states
GPRS Detach
PDU transmission
READYtimer expiry
GPRS Attach
Location atCELL level Location at
RA level
Autonomous cell reselection NCOOr controled by network NC 2( In paquet transfert mode )
Autonomous cell reselection
▼ IDLE (GPRS) State
In GPRS IDLE state, the subscriber is not attached to GPRS mobility management. The MS and SGSN contexts hold no valid location or routeing information for the subscriber. The subscriber-related mobility management procedures are not performed.
Data transmission to and from the mobile subscriber and the paging of the subscriber is not possible. The GPRS MS is seen as not reachable in this case.
In order to establish MM contexts in the MS and the SGSN, the MS shall perform the GPRS Attach procedure.
▼ STANDBY State
In STANDBY state, the subscriber is attached to GPRS mobility management. Pages for data or signalling information transfers may be received. It is also possible to receive pages for the CS services via the SGSN. Data reception and transmission are not possible in this state.
The MS performs GPRS Routeing Area (RA) and GPRS cell selection and re-selection locally. The MS executes mobility management procedures to inform the SGSN when it has entered a new RA. The MS does not inform the SGSN on a change of cell in the same RA. Therefore, the location information in the SGSN MM context contains only the GPRS RAI for MSs in STANDBY state.
The MS may initiate activation or deactivation of PDP contexts while in STANDBY state. A PDP context shall be activated before data can be transmitted or received for this PDP context.
▼ READY State
In READY state, the SGSN MM context corresponds to the STANDBY MM context extended by location information for the subscriber on the cell level. The MS performs mobility management procedures to provide the network with the actual selected cell. GPRS cell selection and re-selection is done locally by the MS, or may optionally be controlled by the network.
An identifier of the cell, the Cell Global Identity including RAC and LAC, is included in the BSSGP header of the data packet from the MS; see GSM 08.18 [21].
The MS may send and receive PDP PDUs in this state. The network initiates no GPRS pages for an MS in READY state. Pages for other services may be done via the SGSN. The SGSN transfers downlink data to the BSS responsible for the subscriber's actual GPRS cell.
The MS may activate or deactivate PDP contexts while in READY state.
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31Introduction to GPRS/EGPRS
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2 GPRS Operation2.3 MS Radio Resource Operating Modes
Packettransfer mode
Packetidle mode
Packetidle mode
Ready Standby
RR
MM
> Packet transfer modeIn packet transfer mode, the mobile station is allocated radio resource providing a Temporary Block Flow (TBF) on one or more physical channels. Continuous transfer of one or more LLC PDUs is possible. Concurrent TBFs may be established in opposite directions. Transfer of LLC PDUs in RLC acknowledged or RLC unacknowledged mode is provided.
> Packet idle modeIn packet idle mode no Temporary Block Flow . Upper layers can require the transfer of a LLC PDU which, implicitly, may trigger the establishment of TBF and transition to packet transfer mode.
> MS RR operating modes vs MS MM states
▼ Packet idle mode
While operating in packet idle mode, a mobile station belonging to GPRS MS class A may simultaneously enter the different RR service modes. A mobile station belonging to either of GPRS MS class B or C leaves both packet idle mode and packet transfer modes before entering dedicated mode, group receive mode or group transmit mode.
▼ Packet transfer mode
When selecting a new cell, mobile station leaves the packet transfer mode, enters the packet idle mode where it switches to the new cell, read the system information and may then resume to packet transfer mode in the new cell.
While operating in packet transfer mode, a mobile station belonging to GPRS MS class A may simultaneously enter the different RR service modes. A mobile station belonging to either of GPRS MS class B or C leaves both packet idle mode and packet transfer modes before entering dedicated mode, group receive mode or group transmit mode.
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32Introduction to GPRS/EGPRS
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Routers
IP network
2 GPRS Operation2.4 Basic Procedures
ipip ipip ip
http httpftp ftpsmtp smtp
1tcp1tcp
wap wap
gtp
SGSN
GGSN
> IP overview
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33Introduction to GPRS/EGPRS
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nK bytes MESSAGE
4K bytes PACKET 4K bytes PACKETTCP
TCPIP IP IP
TCPIP Z Ethernet 1.5k frames
Y Datagrams IP
TCP
x 4k TCP packets
L4
L 3
L2
2 GPRS Operation2.4 Basic Procedures
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34Introduction to GPRS/EGPRS
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DATASHEADER
456
HEADER
57 X 8
456
DATASHEADERIP / X25
HEADER DATASSNDCP
SNDCP
DATASHEADERLLC
RLC/PCU
AIR INTERFACE
57 57
Max 1600Bytes SGSN to MSCRC
TRE / CCU
2 GPRS Operation2.4 Basic Procedures
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2 GPRS Operation2.4 Basic Procedures
> Transmission plane
TCP HTTP FTP SMTP
Physicallayer
Physicallayer
Physicallayer
Physicallayer
Physicallayer
Physicallayer
Physicallayer
L2
IP
UDP
GTP
IP
L2
MAC
L2
IP
UDPLLC
GTP
BSSGP(FrameRelay)
(FrameRelay)
LLC
Um Gb Gn Gi
MSBSS
(with PCU) SGSN GGSN
Application
RLC
MAC
RLC
MAC
IPIP
relay
relay
BSSGP
SNDCPSNDCP
▼ GTP (GPRS Tunnelling Protocol) tunnels user data between GPRS Support Nodes in the backbone network. The GPRS Tunnelling Protocol shall encapsulate all PDP PDUs.
▼ UDP (User Datagram Protocol) carries GTP PDUs for protocols that do not need a reliable data link (e.g., IP), and provides protection against corrupted GTP PDUs.
▼ IP (Internet Protocol) is the backbone network protocol used for routing user data and control signalling. The backbone network may initially be based on the IPv4. Ultimately, IPv6 shall be used.
▼ SNDCP (SubNetwork Dependent Convergence Protocol ) maps network-level characteristics onto the characteristics of the underlying network.
▼ LLC (Logical Link Control) provides a highly reliable ciphered logical link. LLC shall be independent of the underlying radio interface protocols in order to allow introduction of alternative GPRS radio solutions with minimum changes to the NSS.
▼ Relay. In the BSS, this function relays LLC PDUs between the Um and Gb interfaces. In the SGSN, this function relays PDP PDUs between the Gb and Gn interfaces.
▼ BSSGP (Base Station System GPRS Protocol) conveys routing and QoS-related information between the BSS and the SGSN. BSSGP does not perform error correction.
▼ (NS) Network Service transports BSSGP PDUs. NS is based on the Frame Relay connection between the BSS and the SGSN, and may - multi-hop and traverse a network of Frame Relay switching nodes.
▼ RLC/MAC (Radio Link Control / Medium Access Control ). The Radio Link Control function provides a radio-solution-dependent reliable link. The Medium Access Control function controls the access signalling (request and grant) procedures for the radio channel, and the mapping of LLC frames onto the GSM physical channel.
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2 GPRS Operation2.4 Basic Procedures
NSAPI
NSAPITLLITLLI
Radio layers
LLC
GMM/SM SMS
SNDCP
IP
NSAPI i
> MS high protocol layers
▼ SNDCP (Sub-Network Dependent Convergence Protocol)
Data compression, segmentation of large packets, recognition of PDP-PDU sessions (according to their NSAPI), inclusion of QoS (use of SAPIs on the LLC link).
▼ NSAPI (Network Service Access Point Identifier)
This is used for a particular MS to distinguish different PDP contexts (= sessions)
� by the PDP-type: X.25 or IP, or mainly by
� the APN to be reached, or by
� the required QoS.
▼ LLC (Logical Link Control)
Provides a safe link, encrypted and independent of the physical bearer, independent to BSS brand.
▼ TLLI (Temporary Logical Link Identity)
Identifies a logical link with the MS (one TLLI per MS)
▼ GMM/SM (GPRS Mobility Management / Session Management)
MS-SGSN signaling protocol for Gprs Mobility Management/ Session Management
▼ SMS (Short Message Service)
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2 GPRS Operation2.4 Basic Procedures
NMC-NSS
HPLMN
HLRMS
• APN accessible through FPLMN-GGSN ?
• etc ...
✚ MSISDN➝IMSI ➙ network access mode :
For each MS
GPRS | NSS | both➙ subscribed « PDP contexts » (maximum of n) :
• PDP type :
• [PDP address (IP@) ]
• Access point name ( APN) or * (= wild card)
• QoS profile
IP | PPP
n times
> HLR GPRS data
▼ PDP address
Almost always empty. The network then dynamically assigns (using a DHCP server) an IP address to the subscriber when he activates his PDP context (seen later).
▼ PDP contexts
Each PDP context can be considered as a BS (basic service = telephony, fax, etc). A PDP context is a dialog session with an external IP network, identified with an APN. It is not always mandatory to subscribe (in the HLR) to PDP contexts, access to some networks is free. For a user, the traffic of his different sessions will be recognized in the messages by the use of different NSAPIs. A user can declare one of his PDP contexts as the default.
▼ APN (Access Point Name)
The APN represents an IP network. An APN has two parts: the APN-Network Id (example: wanadoo.fr) and the APN-operId (example: mnc...gprs)
� Examples of APN: wanadoo.fr.mnc001.mcc208.gprs,
� APN = * (wildcard) potentially authorizes the MS to activate any APN.
▼ Valid APN
Boolean, if YES, indicates that this APN can be reached through the GGSN of the visited FPLMN.
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2 GPRS Operation 2.4 Basic Procedures
> GPRS attachment
BSS
➁
Authent_info_req()
➂
Authent_info_respq)
⑤
Update_loc_req()
⑥
Insert_subs_data()
Update_loc_ack()
⑦
PLMN
Attach-Request(IMSI) ➀➀➀➀
Attach_resp (P_TMSI)⑧⑧⑧⑧
Attach_complete () ⑨⑨⑨⑨
MS_authentication_procedure➃➃➃➃ GPRS IPbackbone
GGSN
SGSN
N7
HLR
▼ Attach Request.
� The attach_request message is placed in an LLC frame. ①
� The MS sends its IMSI.
▼ Authentication
The SGSN gets the “authentication triplets” from the HLR:
� triplets request message ②
� triplets response message ③
The SGSN performs the “authentication procedure” with the MS: ④
� triplets request message ②
� triplets response message ③
▼ Location Update
The SGSN performs the “location_update procedure” with the HLR:
� location_update request message ⑤
� the HLR transfers the MS_subscription data to the SGSN ⑥
� the HLR terminates the location_update procedure ⑦
▼ Attach Complete
The SGSN terminates the attach_procedure with the MS :
� attach_accept message ⑧ (with a new P_TMSI allocation)
� attach_complete message ⑨ (since a new P_TMSI has been allocated)
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GPRS - CN
2 GPRS Operation2.4 Basic Procedures
LLC layer
TLLI1
GPRS IPbackbone
> GPRS attachment
After a GPRS_Attach procedure The mobile is « c onnected » to the serving SGSN
SGSN1
SGSN2
GGSN1
GGSN2 PDN 2
PDN 1
▼ Attached MS
After running the attach procedure, the MS is “GPRS_attached”:
� a logical connection is established between the MS and the SGSN
� connection established between the peer LLC layers in the MS and the SGSN
� this connection is identified by the TLLI (Temporary Logical Link Identity)
� this logical connection remains established until the MS detaches
� the MS can now access to GPRS services and is reachable for GPRS services
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2 GPRS Operation 2.4 Basic Procedures
> PDP context activation
GPRS Core Network
GPRSbackbone
PDN1
SGSN
DNS
GGSN
GGSN PDN2
DHCP
BSS
PLMN
TLLI1
4
2
3Create_PDP_req (PDN2)
5 Create_PDP_resp (@IP_MS)
Activate_PDP_req (PDN2) ➀➀➀➀
Activate_PDP_resp(@IP_MS)⑥⑥⑥⑥
▼ MS IP address
In case of IP PDP_type access with no additional mobile authentication procedure, the MS IP address is provided by the PLMN, using either the subscription data, or the backbone DHCP server. No additional user authentication is needed on top of the GPRS authentication mechanisms (i.e. using IMSI and authentication triplets)
▼ PDP Context Activation
� ➀ MS requests for a PDP_context activation, providing the name of target Packet Data Network (PDN2 parameter).
� ➁ SGSN queries the backbone Name Server (here DNS) to identify the GGSN giving access to the Data Network PDN2 (here GGSN2).
� ➂ SGSN sends a Create_PDP message to the corresponding GGSN2, in order to setup a GTP tunnel.
� ➃ GGSN2 allocates an IP address to the MS (@IP_MS), using the backbone DHCP server.
� ➄ GGSN2 acknowledges the Create_PDP message to the SGSN, returning the @IP_MS allocated to the MS.
� ➅ SGSN acknowledges the Activate_PDP message to the MS, with the allocated @IP_MS.
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2 GPRS Operation 2.4 Basic Procedures
> PDP context activation
BSS
PLMN
TLLI1
GPRS Core Network
GPRSbackbone
SGSN
DNS
GGSN
GGSN
2
3Create_PDP_req (PDN2)
6 Create_PDP_resp (@IP_MS)
Activate_PDP_req (PDN2) ➀➀➀➀
Activate_PDP_resp(@IP_MS)⑥⑥⑥⑥ISP
INTRANET
DHCP
RADIUS
5
Authentication andaccounting
Address allocation
4
▼ MS address
IP PDP_type access with mobile authentication via a RADIUS. The address allocation server (i.e. DHCP) and/or authentication server (i.e. RADIUS) may be located within the PLMN or in the ISP/Intranet network. Non-transparent access is aimed for corporate intranet access, where additional user authentication is often required.
▼ PDP Context Activation
� The authentication data are piggybacked in the Protocol Configuration Options (PCO) field of the PDP context activation messages ➀ and ➆.
� ➀ , ➁ , ➂ same as for IP PDP_type in transparent access.
� ➃ GGSN performs the user authentication towards a RADIUS server.
� ➄ GGSN allocates an @IP to the MS using the intranet/ISP DHCP server.
� ➅, ➆ same as for a PDP context in transparent access.
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2 GPRS Operation2.4 Basic Procedures
> PDP context activation
LLC layer
GPRS - CN
TLLI1
GPRS IPbackbone
SGSN1
SGSN2
GGSN1
GGSN2 PDN 2
PDN 1TID 1 = IMSI + NSAPI 1
TID 2 = IMSI + NSAPI 2
by the GTP layer
after PDP_context_activation procedures
▼ User data transfer
In order to achieve a proper transfer of User Data, two main protocols are used: GTP (between GGSN and SGSN) and LLC (between SGSN and MS), and two types of logical connections are established:
� MS <-> SGSN. Logical Link used for signaling and data transfer, created at GPRS attach (unique per MS), identified by a TLLI value;
� SGSN <-> GGSN. Created with the activation of PDP context = when opening a session (several per MS), identified each by a TID value.
▼ TLLI (Temporary Logical Link Identity)
Identifies uniquely a MS attached to the GPRS core network (Standby or Ready state).
▼ TID (Tunnel Identity)
Identifies a logical connection ("tunnel") between GGSN and SGSN (for each session of each MS). TID= IMSI+NSAPI.
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2 GPRS Operation2.4 Basic Procedures
> PDP context activation
LLC layer
GPRS - CN
TLLI1
GPRS IPbackbone
SGSN1
SGSN2
GGSN1
GGSN2 PDN 2
PDN 1TID 1 = IMSI + NSAPI 1
TID 2 = IMSI + NSAPI 2
by the GTP layer
after PDP_context_activation procedures
ul/dl data_transfers
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SGSNGGSN
within the MS
MS
over the Gn interface
over the Giinterface
@ MS @server
U-data
@sgsn@ggsn
GTPheader
UDPheader
@ MS @server
U-data
@ MS @server
U-data
@server@ MS
U-data
server
PDN
@ggsn@sgsn
GTPheader
UDPheader
@server@ MS
U-data
@server@ MS
U-data
2 GPRS Operation2.4 Basic Procedures
> User data transfer
▼ User data transfer
Data are transferred from header translation, then encapsulation in underlined protocol data unit.
At the GGSN, the IP address of the MS is used to retrieve a PDP context and therefore a TID and the address of the current SGSN.
At the SGSN, the TID is used to work out the NSAPI and the IMSI (therefore the TLLI). If the MS is ready, no need for paging because the MS is located to the exact cell.
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2 GPRS Operation 2.5 Charging
> Charging process
MS
PDNGPRSBACKBONE
GGSNSGSNBSSTLLI
CCBS
CG
AttachmentM_CDR
PDP CONTEXT ACTIVATION AND DATA TRANSFERT
S_CDRG_CDR
FTP
GTP
▼ CDR (Call Detail Record)
CDRs are used for subscriber charging, statistics and location purposes.
Three types of CDR are managed within the GPRS backbone:
� M-CDR related to the GPRS mobility of a mobile station
� S-CDR related to PDP-contexts activation and data transfers as seen by the SGSN
� G-CDR related to PDP-contexts activation and data transfers as seen by the GGSN
CDRs, generated by the xGSN, are then sent to the CG (Charging Gateway) :
� periodically,
� using reliable transfers (GTP over TCP)
The CG forwards those CDRs to external CCBS (Customer Care and Billing System)
▼ CDR content
Here are the main information in the CDR :
� IMSI
� location information (LAC + RAC + Cell)
� APN
� PDP-context identifier
� PDP-context start time and duration
� negotiated QoS
� volume of data sent / received
� source and destination PDP addresses,
� ….
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2 GPRS Operation 2.5 Charging
> Charging process
INTER PLMN NETWORK
HPLMN GGSN PDNBG
CCBS
CG
S_CDRHOME PLMN
MS
SGSN
BSS
TLLI VPLMNBG
CG CCBS
VISITED PLMN
G_CDR
▼ Charging data collection for inter-PLMN charging
� Use of G_CDR and S-CDR as specified by GSM 12.15
� Inter-operator agreement to transfer between Billing Systems
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Public Internet
2 GPRS Operation 2.6 Security
1- Secured network access• Authentication of MSs and confidentiality of their identity• Possibility of encrypting user data• Possibility of verifying IMEI with an EIR (Gf)
2- Secured backbone IP networkFirewall = application-level filteringFiltering by access lists (in the GGSNs)
GPRS Network
3- Secured intranet accessAPN with mandatory subscriptionAPN with access lists APN with tunneling on Gi (IPsec)
▼ Authentication and confidentiality
As in GSM, by security triplets and the use of the TLLI/P_TMSI instead of the IMSI.
▼ Encryption
The LLC frame is encrypted, so encryption from the MS to the SGSN and not just on Um.
▼ Firewall
Filtering function installed on routers (ex: GGSN). Packets are rejected by filtering at application level (for example: in http, some URLs are barred). Also makes it possible to hide the IP addresses of MSs and backbone entities from external hosts (Network Address Translation function).
▼ Access Lists (IP addresses lists)
A function of Cisco routers (and therefore of GGSNs). Each APN is linked to two lists of IP addresses to be checked during the PDP context activation phase (calling address and called address in both UL and DL directions).
These lists are therefore used to protect access to the operator's backbone IP, but also to filter the access to external PDNs.
At the GGSN, some APNs can be declared "with mandatory subscription" (at the HLR) and therefore inaccessible to other MSs.
▼ Tunneling
Several ways:
� by IPsec (Secured IP) = IP version in which the user data is encrypted (IP datagrams payload but not their header). Or by Generic Routing Encapsulation (GRE)
� by PPTP (Point-To-Point Tunneling Protocol). Refer to ANNEX for PPP Tunneling.
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48Introduction to GPRS/EGPRS
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Time allowed :
5 minutes
2 GPRS Operation Exercise (1/3)
– True or False?
– The GGSN reads the header of user packets arriving from the PDN
– The GPRS HLR knows the location of an MS to the nearest RA
– With each web page downloaded, a new PDP context must be
activated
– A CDR is generated for each packet sent or received
– The SGSN can be considered as PMSC and PVLR
– A TLLI is a virtual connection between a GPRS attached mobile and the
GGSN
▼ PMSC: Packet MSC.
▼ PVLR: Packet VLR.
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49Introduction to GPRS/EGPRS
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Time allowed :
5 minutes
2 GPRS Operation Exercise (2/3)
– True or False ?
– The Charging gateway provides a single interface towards the billing centers
– No need for paging to send a packet to a mobile in the "Ready" state
– Attachment to the network does not involve GGSN
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50Introduction to GPRS/EGPRS
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Time allowed :
5 minutes
2 GPRS Operation Exercise (3/3)
– What interfaces of the GPRS NSS does a packet cross from a PDN to an MS?
– Why , theoretically, is an RA smaller than an LA?
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51Introduction to GPRS/EGPRS
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Thank you for answeringthe self-assessment
of the objectives sheet
2 GPRS OperationEvaluation
> Objective : to be able to describe the organization of a GPRS network : architecture, interfaces, protocols,…
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 52
All rights reserved © 2004, Alcatel
3 The Base Station Subsystem
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53Introduction to GPRS/EGPRS
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3 The Base Station SubsystemSession presentation
> Objectives :
• To be able to briefly describe the datainterchange mechanisms through the BSS
> Program :
• 3.1 3GPP Position
• 3.2 Alcatel’s Choice
• 3.3 Layered Model
• 3.4 Gb Interface
• 3.5 Radio Interface
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54Introduction to GPRS/EGPRS
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3 The Base Station Subsystem3.1 3GPP Position> PCU function
BSSBTS
CCU PCU
BSC SGSN
BSSBTS
CCU
BSC SGSNPCU
BSSBTS BSC SGSN
CCU PCU
▼ PCU functions
RLC and MAC layers: LLC frame transportation (segmentation/reassembly),
� Gb interface end point,
� network access functions (radio resource management),
� radio channel management (power control, congestion control, etc).
▼ CCU functions
� encoding suited to radio channels,
� radio measurements (receive quality, signal level, "timing advance" management).
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3 The Base Station Subsystem3.2 Alcatel’s Choice
> PCU function
BTS
CCU
BSC SGSNMFS
Abis Ater Gb
GSL
LLC Transmission check between SGSN and MS
RLC Transmission check between PCU and MS
GCH transmission check between PCU and TRE
MFS is just the name of the rack containing PCU functions
PCU
BSS
▼ The Multi BSS Fast packet Server (MFS):
▼ MFS is just the namee of the rack containing PCU funct ions
� performs the GPRS Packet Control Unit (PCU) functions (3GPP 03.60 standard),
� manages the Gb interface with the GPRS & EGPRS core network,
� performs the Serving Mobile Location Center (SMLC) functions,
� manages the SAGI interface with the A-GPS server.
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3 The Base Station Subsystem3.3 Layered Model
BTS MFS SGSNMS
BSSGP
Gb
Physicallayer
Framerelay
RLC
MAC
RLC
Physicallayer
Framerelay
BSSGP
Um Abis/Ater
PCU
IP
LLC
GMMSM
relay
LLC
GMM SNDCPSM
relayPhysical
layerPhysical
layerL2-GCHL1-GCH
L2-GCHL1-GCH
MAC
SNDCP
> User plane
▼ For GPRS TRAFFIC, the BSS simply relays the LLC frames between the MS and the SGSN.
▼ BSSGP = BSS Gprs Protocol. Functions:
� to relay LLC frame over the Gb, with no guarantee of integrity (relaying user data and GMM / SM messages : session, RA_update and paging procedures). Conceals the FR layers for the LLC layer.
� SGSN-MFS signaling = management of Gb interface objects (flush, paging, resume suspend, LLC-discarded and other procedures).
� cell-SGSN traffic management (identified by BssgpVCs): in particular cell update management (in the same RA): the BSSGP header always indicates the current cell so if a "ready" MS moves into a new cell, then the SGSN stores this new cell and sends all the unacknowledged LLC_PDUs to it (DL).
▼ The concept of handover has no meaning in packet switching (GPRS). There is no "circuit" to re-establish!
▼ RLC = Radio Link Control. (Provides a safe link for transporting LLC-PDUs in acknowledged or unacknowledged mode, LLC-PDU segmentation into blocks and reassembly, management of TBF contexts. RLC depends on the physical bearer: data encoding, error control and flow control suited to GSM channels.
▼ MAC = Medium Access Control. Multiplexing of RLC frames onto PDCH (transfer of blocks over the different PDCHi). Including traffic sharing over several TSs or, conversely, the use of one TS for several users.
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BSC MFSBTSMS
3 The Base Station Subsystem3.3 Layered Model
Gb
L2-GSL L1-GSL
BSCGPBSCGP
L2-GSL L1-GSL
physicallayer
RRM
AterUm
relay
Abis
relayphysical
layer
RRM
> Signaling plane
▼ BSCGP protocol
� administration interface of Radio Resource management :
� (de)allocation of PDCH and MPDCH within a cell
� activation / release of PDCH
� System control information:
� BSC reset procedure
� cell and GIC group state management
� Radio signalling :
� GSM / GPRS paging,
� GPRS access procedure
▼ RMM protocol
� dynamic allocation of Radio Resources to a MS :
� radio blocks from one or several PDCH
� for uplink or downlink data transfers
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 58
58Introduction to GPRS/EGPRS
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NSE2
SGSN
NSE1NSE1
NSE2
F.RF.RNetworkNetwork
PCM
3 The Base Station Subsystem3.4 Gb Interface
PCM
PCM
BVCI=2
BVCI=1
BVCI=3
BVCI=5
BVCI=6
BVCI=4
BSC1
BSC2
GPRS Core Network sideBSS side
BC PCMBCPVC
BC BCPVC
NSVC1
NSVC2
PCM
PCM
PCM
BC PCMBCPVC
BC BCPVC
NSVC3
NSVC4
BVCI=2BVCI=2
BVCI=1BVCI=1
BVCI=3BVCI=3
BVCI=5BVCI=5
BVCI=4BVCI=4
BVCI=6BVCI=6
> Managed entities
▼ For GPRS TRAFFIC, the BSS simply relays the LLC frames between the MS and the SGSN.
▼ BSSGP = BSS Gprs Protocol. Functions:
� to relay LLC frame over the Gb, with no guarantee of integrity (relaying user data and GMM / SM messages : session, RA_update and paging procedures). Conceals the FR layers for the LLC layer.
� SGSN-MFS signaling = management of Gb interface objects (flush, paging, resume suspend, LLC-discarded and other procedures).
� cell-SGSN traffic management (identified by BssgpVCs): in particular cell update management (in the same RA): the BSSGP header always indicates the current cell so if a "ready" MS moves into a new cell, then the SGSN stores this new cell and sends all the unacknowledged LLC_PDUs to it (DL).
▼ The concept of handover has no meaning in packet switching (GPRS). There is no "circuit" to re-establish!
▼ RLC = Radio Link Control. (Provides a safe link for transporting LLC-PDUs in acknowledged or unacknowledged mode, LLC-PDU segmentation into blocks and reassembly, management of TBF contexts. RLC depends on the physical bearer: data encoding, error control and flow control suited to GSM channels.
▼ MAC = Medium Access Control. Multiplexing of RLC frames onto PDCH (transfer of blocks over the different PDCHi). Including traffic sharing over several TSs or, conversely, the use of one TS for several users.
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 59
59Introduction to GPRS/EGPRS
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3 The Base Station Subsystem3.4 Gb Interface
GPRS Core Network sideBSS side
> Protocols
SGSNPacket Control Unit function(PCU)
BSS GPRS Protocol(BSSGP)
BSS GPRS Protocol(BSSGP)
Network Service Control(NSC)
Network Service Control(NSC)
BVCI=2
BVCI=1
BVCI=3
BVCI=5
BVCI=6
BVCI=4
BSC1
BSC2
Sub-Network Service(SNS)
Physical layer
Sub-Network Service(SNS)
Physical layer
Frame Relay
BVC
NS-VC
NSE
PVC
PCM PCM
BC
▼ For GPRS TRAFFIC, the BSS simply relays the LLC frames between the MS and the SGSN.
▼ BSSGP = BSS Gprs Protocol. Functions:
� to relay LLC frame over the Gb, with no guarantee of integrity (relaying user data and GMM / SM messages : session, RA_update and paging procedures). Conceals the FR layers for the LLC layer.
� SGSN-MFS signaling = management of Gb interface objects (flush, paging, resume suspend, LLC-discarded and other procedures).
� cell-SGSN traffic management (identified by BssgpVCs): in particular cell update management (in the same RA): the BSSGP header always indicates the current cell so if a "ready" MS moves into a new cell, then the SGSN stores this new cell and sends all the unacknowledged LLC_PDUs to it (DL).
▼ The concept of handover has no meaning in packet switching (GPRS). There is no "circuit" to re-establish!
▼ RLC = Radio Link Control. (Provides a safe link for transporting LLC-PDUs in acknowledged or unacknowledged mode, LLC-PDU segmentation into blocks and reassembly, management of TBF contexts. RLC depends on the physical bearer: data encoding, error control and flow control suited to GSM channels.
▼ MAC = Medium Access Control. Multiplexing of RLC frames onto PDCH (transfer of blocks over the different PDCHi). Including traffic sharing over several TSs or, conversely, the use of one TS for several users.
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60Introduction to GPRS/EGPRS
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3 The Base Station Subsystem3.5 Radio Interface 1/8
> GPRS / EGPRS throughput
Coding Scheme Modulation Maximum rateper PDCH (kb/s)
CS2
CS1
GMSK
GMSK
13.4
9.05
CS4
CS3
GMSK
GMSK
21.4
15.6G
PR
S
MCS9
MCS8
8-PSK
8-PSK
59.2
54.4
MCS7
MCS6
MCS5
MCS4
MCS3
MCS2
MCS1
8-PSK
8-PSK
8-PSK
44.8
29.6 / 27.2*
22.4
17.6
14.8 / 13.6*
11.2
8.8
GMSK
GMSK
GMSK
GMSK
* in case of padding
EG
PR
S
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> Coding schemes
Bad radio conditionMax security
Good radio conditionMin security
Maximum number of bits to have security
Max number of bits for user data
POOR USER BIT RATE BETTER USER BIT RATE
CS2CS1 CS3 CS4
3 The Base Station Subsystem3.5 Radio Interface 2/8
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3 The Base Station Subsystem3.5 Radio Interface 3/8
> GMSK / 8-PSK modulations
GMSK
8-PSK
1 0 1 1
001 101 011 001
GMSK270 kb/s
8-PSK810 kb/s
Gross bit rateper carrier1 bit per
Symbol
3 bitS perSymbol
8 PSK has 3times more capacity than GMSK
One TS 142 symbols142 BitsONE TS
One TS 142 symbols426 BitsONE TS
▼ Transmission and reception data flows are the same for GPRS and EGPRS, except for EGPRS MCS-9, MCS-8 and MCS-7, where 4 normal bursts carry 2 RLC blocks (1 RLC block within 2 bursts for MCS-9 and MCS-8).
▼ Radio blocks are transported on the air interface (Um) over 4 consecutive normal bursts of the TDMA frame.
▼ The GMSK normal burst is composed of 156.25 symbols (1 bit for 1 symbol):
� 6 tail symbols,
� 26 training sequence symbols,
� 114 encrypted symbols,
� 2 stealing flags (2 symbols),
� 8.25 guard period (symbols).
� For GMSK, the radio blocks are transported by 114 x 4 = 456 symbols.
▼ The 8-PSK normal burst is composed of 156.25 symbols (3 bits for 1 symbol):
� 6 tail symbols,
� 26 training sequence symbols,
� 116 encrypted symbols (there is stealing flags),
� 8.25 guard period (symbols).
� For 8-PSK, the radio blocks are transported by 116 x 4 = 456 symbols.
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> Transmission Rate with 8 PSK modulation
MCS9
59,2k
MCS8
54,4k
CHANNEL
MCS7
44,8k
MCS6
29,6k
MCS5
22,4k
MCS4
17,6k
MCS3
14,8k
MCS2
11,2k
MCS1
8,8k
3 The Base Station Subsystem3.5 Radio Interface 4/8
Maximum number of bits to have security Max number of bits for user data
Bad radio condition Good radio condition
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> Impact of EGPRS (Edge) on terrestrial transmissions in BSS
3 The Base Station Subsystem3.5 Radio Interface 5/8
Extra capacity Extra capacity
Abis AterGMSk and Not a good transmission
CS1 about 9K
MCS9 ABOUT 59K
8PSK good transmission
Extra capacity Extra capacity
MFSPCU
BTSTRX
BSCrelay
PDCH
BTSTRX
BSCrelay
MFSPCU16k resource 16k resourcePDCH
Extra capacity Extra capacity
Extra capacity Extra capacity
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> Resources allocation according to the MCS
QUALITY OF TRANSMISSION LOT OF BITS LOST
INCREASE SECURITY DECREASE USEFUL TRANSMISSION RAT E
Extra capacity Extra capacity
MCS n
Extra capacity Extra capacity
MFSPCU
BTSTRX
BSCrelay
PDCH
Extra capacity Extra capacity
MCS n-1
PDCH
Extra capacity Extra capacity
Extra capacity Extra capacity
MFSPCU
BTSTRX
BSCrelay
Extra capacity Extra capacity
Can be allocated to another PDCH
Can be allocated to other PDCH
3 The Base Station Subsystem3.5 Radio Interface 6/8
▼ When the operator decide that the TRX will run MCS n all the terrestrial resources will be allocated , but if the quality of the radio transmission is bad the PCU decides to increase the security on the air interface, the useful transmission rate on the PDCH will be decreased and less capacity will be needed on the terrestrial transmission .
▼ The resource which is not used a that time can be allocated to another TRX if needed at BTS level
▼ The RLC blocks coming from different are multiplexed on the common resource for all the PDCH in the TRX which is called M EGCH (Multiplexed EGCH)
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 66
66Introduction to GPRS/EGPRS
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networkMSstart
of TBF1end ofTBF1 TBF2 TBF3 TBF4
timefULi
Packet Channel Request
Packet Resource Assignment (list of PDCHi, token=T,TFIk)
MS starts listening to all DL blocks token value on the allocated PDCHi
SEND on block b+1 (TFIk)
in block b token =T ?
Y
N
Ø Ø T T Ø T Ø T T T ØDL PDCHi
? Ø Ø TFIk TFIk Ø TFIk Ø TFIk TFIk TFIkUL PDCHi
3 The Base Station Subsystem3.5 Radio interface 7/8> UL transfer
PCU
TBF MAC
▼ This slide demonstrate that the radio resources (blocks) are used only when data need to be transferred (LLC-PDU) : dynamic radio resource allocation. As a matter of fact, an MS shall specify its radio resource request at initiation of each TBF for a better optimization of radio resource & MS capabilities.
▼ A TBF (the blue shape) comprises one or more consecutive LLC-PDUs.
▼ Temporary (Block) Flow Identity = TLLI + sequential number, used by the network to recognize data from different MSs. Identifies uniquely a TBF in one direction within a cell.
� The blocks are dynamically allocated upon the use of a token (Uplink State Flag) allocated to the MS at TBF establishment. Any DL block includes a USF in the header.
� The mobile "listens" to the PDCHi assigned, when block b (in DL) contains USF = T, the MS shall send one PDTCH in UL on block b+1 on the UL PDCHi.
▼ The theoretical maximum of 160 kbit/s is given for one MS which would have 8 PDCHs of 21.4 kbit/s each. Those MS are yet to be available on the market place.
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67Introduction to GPRS/EGPRS
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PS PagingPaging Request ("packet")
Packet Paging Response
Packet Resource Assignment (list (PDCHj),TFIz)
The MS consumes the content of block b
in block b, TFI=TFIz ?
Y
N
PCU SGSN
UL TBF: refer toprevious slide
MS PDU
MS starts listening to all DL blocks TFI value on the allocated PDCHj
Ø Ø Z Z Ø Z Ø Z ZDL PDCHj
3 The Base Station Subsystem3.5 Radio interface 8/8
> DL transfer
MS IN STANB BYMODE
MS IN READYMODE
▼ In DL, each time an LLC-PDU is received, if there is no TBF in progress, it is essential to “establish" one.
▼ To respond to the paging, the MS needs to send a "paging response" to the SGSN (GMM) encapsulated in an LLC_PDU. This response is carried by an UL TBF.
▼ Upon reception of the Paging response, the SGSN can send the DL PDU (LLC frame) to the MS through the MFS.The MFS shall establish a DL TBF with the MS.
▼ DL TBF: each block of the DL TBF are identified by the DL TFI = TFIz
▼ After completion of the TBF establishment phase, the MS listen to all the DL blocks on the allocated PDCHs and keeps the blocks tagged with the TFIz.
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 68
68Introduction to GPRS/EGPRS
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Time allowed :
5 minutes
3 The Base Station Subsystem Exercise (1/2)
– True or False?
– The SGSN is linked to the BSS by an interface based on the Frame Relay protocol
– For each cell, the number of channels which can be used for GPRS traffic is operator-configurable
– If a user packet is lost at the Gb interface, it can be recovered using frame relay protocol mechanisms
– The LLC protocol is independent of the type of BSS employed
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 69
69Introduction to GPRS/EGPRS
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Time allowed :
5 minutes
3 The Base Station Subsystem Exercise (2/2)
– True or False?
– In a cell, a TRX can carry eight PDCHs
– One PDCH can be allocated in its entirety to a single user
– If necessary, blocks on different PDCHs can be allocated to a single user
– The NSEI is the identifier used by the SGSN to indicate the destination cell of a LLC frame to the MFS
– The same quantity of PVCs is declared on the MFS and SGSN sides
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70Introduction to GPRS/EGPRS
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Thank you for answeringthe self-assessment
of the objectives sheet
3 The Base Station SubsystemEvaluation
> Objective : To be able to briefly describe the data interchange mechanisms through the BSS
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 71
All rights reserved © 2004, Alcatel
4 Alcatel Solution
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4 Alcatel SolutionSession presentation
> Objectives: to be able to characterize the solutionoffered by Alcatel
> Program:
• 4.1 GPRS Network Overview
• 4.2 Alcatel 9135 MFS
• 4.3 Packet Switched Core Network
• 4.4 GPRS Network Management
• 4.5 Alcatel QoS Offer
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 73
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GPRS Core Network
4 Alcatel Solution 4.1 GPRS Network Overview
BSS1
BSC
BTS
BTS
BSS--
BSC
BTS
BTS
A9135
MFS
BSS2BTS
BTS
BSC
A9135
MFS
GSM/GPRS common servers
HLR SMS-CMSC
GPRS IPbackbone
Radio subsystem
FrameRelay
network
BorderGateway Inter-PLMN
backbone
Internet
Intranet
SGSN
SGSN
accessrouter
SCP
CAMEL & IP basedPrepaidServices
Firewall
Charging Gateway
OMC-CN
iGGSN
▼ Within the radio subsystem :
� Existing Alcatel BTS and BSC from GSM are reused for GPRS :
� no need of hardware change to provide GPRS features
� need just software upgrade
� The GSM-BSS now includes a proprietary equipment :
� Alcatel A9135 = MFS (Multi BSS Fast packet Server)
� which deals with the GPRS PCU functions
▼ Within the GPRS Core Network :
� both SGSN and iGGSN are Alcatel proprietary equipments
� Charging Gateway and OMC-CN are Alcatel components based on HP platform
� Firewalls, Border gateway and access routers are standard IT components
▼ The HLR, MSC, SCP and SMS-C are reused from the GSM-NSS
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74Introduction to GPRS/EGPRS
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Telecom Subsystem
4 Alcatel Solution 4.2 Alcatel 9135 MFS
Control Subsystem
Gb ifA-ter if
BSC1
BTS
BTS
> Functional architecture
GPU1PCU
GPU2PCU
S
G
S
N
LAN x 2
OMC-RM
F
S
BSC2
BTS
BTS
GPU1PCU
GPU1PCU
▼ The duplex "Control subsystem" (two DS10 in active/standby mode, with 2 shared disks) :
� controls the “telecom subsystem” (initialization, supervision, defence)
� provides the management interface (OMC-R or local maintenance terminal)
▼ The “Telecom subsystem” is composed of GPU boards :
1. GPRS Processing Unit (GPU).
2. Each GPU board performs the PCU functions towards the BSC and the SGSN
� 16 PCM ports per GPU board
� some PCM ports connected to the BSS, the other to the SGSN
▼ There are two different configurations regarding the support of BSC by the GPU boards :
� only one GPU board supporting each BSC (in the B6.2 release)
� multiple GPU boards supporting each BSC (from the B7 release)
© Alcatel University – 3FL10472ACAAWBZZA Ed.02 Page 75
75Introduction to GPRS/EGPRS
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PCU
PCU
PCU
PCU
PCU
SGSN
PMSCPVLR
MFS
FRAME
RELAY
120 CICs
120 GICs 16K
TC SM
PVC
BEARER CHANNEL
Muxed ATer
A Interf
Gb
BSC
BSC
BSC
BSC
BSC
MSC
4 Alcatel Solution 4.2 Alcatel 9135 MFS CONNECTIONS
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4 Alcatel Solution 4.2 Alcatel 9135 MFS
1 BSXTU11 GPU (+1)
maxi
1 BSXTU11 GPU (+1)
maxi
1 BSXTU11 GPU (+1)
maxi
1 BSXTU11 GPU (+1)
maxi
2 DS 10Control
sub-rack
2 DS 10Control
sub-rack
2 or 4 Switches3 COM 3300
+ IOLAN module
2 or 4 Switches3 COM 3300
+ IOLAN module
> Rack layout
▼ The "Control sub-rack" part is duplex (two DS10 in active/standby modes).
▼ each BSXTU sub-rack contains a maximum of 12 JBGPU boards.The GPRS traffic of one BSC can be handled by several GPUs (up to six are foreseen from the same MFS rack)Since B7, a full MFS contains from 4 to 22 BSS (BSC), due to multi-GPU feature
� 4 BSS per MFS: 2* (1 BSS / 6 GPU)+(1 BSS / 5 GPU)� 22 BSS per MFS: 22*(1 BSS/GPU)
▼ One JBGPU board (= 1 PCU) offers 480 PDCH. Two uses of JBGPUs :
1. One JBGPU for each BSC, (Ater interface), so one MFS serves a maximum of 22 BSCs.
2. With 240 PDCH per GPU, a BSC can offer up to 6*240 = 1440 PDCH
3. To be connected to the FR network (Gb interface).
▼ Fast ethernet Switches (100 Mb/s) made by 3COM: 2 or 4 (as needed) to build LANs to which are connected
� the Nectar stations (DS10)
� GPU boards
� printers and craft terminals (for local management, the terminal is called IMT = Installation & Maintenance Terminal)
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4 Alcatel Solution 4.2 Alcatel 9130 MFS (1/3)
ATCAshelf
ATCAshelf
▼ This platform is a high availability distributed platform composed of blades compliant with the Advanced Telecom Computing Architecture (ATCA) open standard
▼ ATCA has been developed by the PCI Industrial Computers Manufacturers Group (PICMG).
▼ The related specifications are described in the PICMG 3.0 R1.0.
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78Introduction to GPRS/EGPRS
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ATCAshelf
ATCAshelf
MFS
LIU LIU
MFS
MFS
O
M
C
P
S
S
W
S
S
W
O
M
C
P
GP
GP
GP
GP
GP
GP
GP
GP
GP
GP
4 Alcatel Solution 4.2 Alcatel 9130 MFS (2/3)
General Option 1 Option 2ATCA shelf content
▼ LIU: Line Interface Unit – to collect the external PCM connections
▼ GP: GPRS Processing module
▼ OMCP: O&M Control Processing board – the control stations,
▼ SSW: Subrack SWitch
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79Introduction to GPRS/EGPRS
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4 Alcatel Solution 4.2 Alcatel 9130 MFS (3/3)
GPGPGPGPGP
GP
GPGPGPGP
MUX
OMCP
MUX
16 LIU X 16 E1
LIU
E1 connections
Abis
LIU
Ater
OMCP
S
S
W
S
S
W
MFS
9 PCU + 1SPARE
▼ LIU shelf: Multiplexes/demultiplexes and cross connects all E1 external links to/from NE multiplexed links (n E1 over Ethernet) on the TP and the GP board. Equipped with two Mux boards and n LIU boards, depending on capacity.
▼ The LIU shelf hosts Two MUX boards which collect the E1 links from the 16 LIU boards on 16 serial links at 36.864 Mbit/s and build packets sent towards up to 32 directions (125ms each) on a Gigabit Ethernet link.
▼ SSW: it’s an Ethernet switch which allows exchanges between all platform elements and externalIP/Ethernet equipment.
▼ OMCP: these control stations are used to process defense functions and platform Operation, Administration and Maintenance (OAM) generic services..
▼ GP: Manages the user plane packet data flow processing.
▼ Ethernet links on the IP ports of the SSW switch: these links connect the platform to external IP equipment (i.e. OMC-R, external alarm box).
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> iGGSN
4 Alcatel Solution 4.3 Packet Switched Core Network
GPRSsignaling & userPlane Blades
GPU
Gb
Ethernet LAN (internal com.) Switching & Routing
O&M, Charging
SS7 Blades
Pilot Blades> SGSN
Vigilon
Senteon
WN
PDN1
PDN2
GPRS IP Backbone
OMC-CNChargingGateway
Intra-PLMNDNS
towards Prepaid Servers
O&M & service provisioning
session control logic
GTP control & user planes
WN
Gr, Gs,
Gd, Ge
▼ The SGSN is ATCA based component (Advanced Telecom Computing Architecture). The main functions are distributed
over different hardware modules :
� SS7 network interfaces (Gs, Gr, Gd) by a number of ATCA SS7 blades,
� Gb interface by a number of Alcatel proprietary GPU boards,
� SGSN O&M and GPRS charging agent (initialisation, defense, O&M, and CDR) by a cluster of ATCA Pilot blades,
� GPRS signaling and user traffic handling by a number of ATCA control & user plane blades
� SGSN internal communication, switching and routing of user traffic by a dedicated Ethernet switch
▼ The iGGSN is an Alcatel proprietary equipment, where the main functions are distributed over 3 hardware modules :
� Vigilon server for iGGSN O&M, subscriber configuration and service provisioning,
� Senteon server as a control logic for subscription and credit check during session establishment phase,
� WN1200 node for full 3GPP GTP services
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4 Alcatel Solution 4.3 Packet Switched Core Network
SGSN rack iGGSN rack
WN1200
Senteon 1&2
GPU boards
Ethernetswitch/routers
Ethernetswitch/routers
pilot blades
SS7 blades
GPRS control& user plane
blades
ATCA platform
Internal control LAN
backbone rack
NS500
NS500
Firewalls
external DNS
NTS150NTS150
NTP Servers
Intra-PLMNDNS/DHCP
border router
access router
Gn switches
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NMCQ3
MFS
4 Alcatel Solution 4.4 GPRS Network Management
SGSN
NTPDNS/DHCP BG
BTS
BTS
BSC1
BTS
BSC2
OMC-CN
Core Network part
Radio part
OMC-R
Charging Gateway
> Dedicated OMCs
iGGSN
▼ OMC-R: Called Alcatel 1353 RA = management of the radio subsystem :
� Alcatel 9135 MFS.
� BSCs and associated BTSs
▼ OMC-CN : called ALMA 1364 GPRS = management of the Core Network :
� the SGSN server
� the SGSN router
� the GGSN.
� The Charging Gateway (alarm supervision)
� the DNS/DHCP server (supervision)
� the GPRS network level (APN and Routing Areas)
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4 Alcatel Solution 4.5 Alcatel QoS offer
ETSI R’97/98 QoS attributes Alcatel Offer
Precedence class Mean throughputclass
Delay class Resulting QoS class
(4) Best Effort
1, 2 or 3
1, 2 or 3
1, 2 or 3
1, 2 or 3
any
(3) Low priority
Normal, High priority
(2) Normal priority
(1) High priority
any
any
Best Effort
specified, except BE
specified, except BE
Best-Effort
Best-Effort
Best-Effort
Normal
Premium
Reliability class: as required by the MS
> R97/98 QoS compliance
▼ These QoS attributes are associated with a PDP context performed by a R97/98 MS
▼ The five QoS parameters of the standard define more than 60 combinations ! Which is too much and leeds to simplification
:
� Too complex to implement,
� Many of the combinations have no meaning!
� The standard "allows" more simple QoS implementations.
� “-” = any value.
� In bold, the main criterion for definition of the resulting QoS.
▼ Best effort = inexpensive, comparable to the Internet (no commitment). Ideal for foraging on the internet.
▼ Normal: Comparable to an intranet.
▼ Premium: Expensive, high performance.
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4 Alcatel Solution 4.5 Alcatel QoS offer
Traffic handling priorityR99 Traffic class R97/98 Bearer QoS class
Premium
Premium
Premium
Normal
Normal
conversational
streaming
interactive
interactive
interactive
-
-
1
2
3
Best Effortbackground -
> R97/98 QoS mapping into R99 QoS
▼ The mapping of R97/98 QoS attributes to R99 QoS is applicable in the following cases :
� hand-over of PDP context from GPRS R97/R98 SGSN to GPRS R99 or UMTS SGSN
� when a R99 MS performs a PDP context activation in a R99 SGSN with a R97/98 GGSN
� when the SGSN has received R97/98 QoS subscribed profile, but the MS is R99
▼ The mapping of R99 QoS attributes to R97/98 QoS is applicable in the following cases :
� PDP context is handed-over from GPRS R99 to R97/R98
� when a R99 MS performs a PDP context activation in a R99 SGSN while the GGSN is R97/98
� when the SGSN sends user data to the BSS for a R99 MS
� when the SGSN has received R99 QoS subscribed profile but the MS is R97/98
� in the new SGSN, during an inter-SGSN RA_update procedure, or inter-system change, on receipt of the R99 QoS
attributes from the old SGSN
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Time allowed :
5 minutes
4 Alcatel Solution Exercise (1/2)
– True or False?
– Implementing GPRS in the BSS simply entails adding A9135 or A9130 MFS servers
– The iGGSN is an Alcatel proprietary equipment
– The SGSN server is an Alcatel proprietary equipment based on IT devices
– The DNS/DHCP servers used in the GPRS Core Network are IT standard servers
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Time allowed :
5 minutes
4 Alcatel Solution Exercise (2/2)
– True or False?
– GPRS Core Network equipments are managed from an OMC- CN
– GPRS radio subsystem (BSS) equipments are managed from an OMC-R
– Alcatel GPRS network handles simultaneously the UMTS QoS classes (R99 QoS parameters) and the GPRS QoS profiles (R97/98 QoS attributes)
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Thank you for answeringthe self-assessment
of the objectives sheet
4 Alcatel SolutionEvaluation
> Objective : to be able to characterize the solution offered by Alcatel
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5 Annex and Glossary
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5 Annex 1Coding Schemes : CS1 -> CS4
0
5
10
15
20
0 10 20 30
Cha
nnel
rat
e (k
bps)
C/I (dBm)
CS4
CS3
CS2
CS1
BACK
▼ The data rate on a PDCH depends on the coding scheme :
� for CS-1: PDCH data rate = 9.05 kbit/s (poor radio conditions or BSS signaling)
� for CS-2: PDCH data rate = 13.4 kbit/s (better radio conditions)
� for CS-3: PDCH data rate = 15.6 kbit/s
� for CS-4: PDCH data rate = 21.4 kbit/s.
▼ The system selects automatically the best coding scheme :
� the data rate is set according to the current C/l.
� maximum data rate (160 kbit/s) only possible with CS4 on 8 parallel channels
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UMTS
2 Mbps
384 Kbps
EDGEGPRS
160 Kbps
64 Kbps
HSCSD
Bit rate
CS data - SMS, 9.6Kbps
9.6 Kbps
Technology
5 Annex 2GPRS compared to other technologies
▼ SMS : With GPRS, the 160-character barrier for short messages will be able to be broken (when SMS over GPRS is implemented).
▼ High Speed Circuit-Switched Data : This still involves circuit switching, meaning that, with a continuous use of radio resources, so billed by time. HSCSD is based on the assignment of several traffic channels (TCH) to a single MS to offer a higher bit rate. HSCSD is suited for services requiring a minimum bandwidth guaranteed.
▼ EDGE : (Enhanced data rates for GSM evolution) is a technology previously developed by Ericsson, based on TDMA and offering a maximum theoretical speed of 384 kbit/s (8 channels, each 48 kbit/s, using a new modulation scheme: 8-PSK, eight-phase shift keying, instead of GMSK for GSM and GPRS).
▼ EDGE-specific MTs are required! The BSS remains the same, except for the implementation of EDGE TRX (Evolium product line).Alcatel will offer EDGE from release B8 onwards. This is an important step towards UMTS
▼ UMTS : requires a new Radio Access Network based on W-CDMA technology.The UMTS standard is part of the Third Generation (3G). Together with CDMA 2000 and other systems, they form a set of ITU radio access technologies standardized by IMT 2000.
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TFI = Temporary Flow Identifier
2 89 2 90 4 21 4 22 2 91 2 92 9 2 4 23 2 93 2 94 4 29 1
TBF = Temporary Block Flow BSN = Block Sequence Number
9 29 1 9 3 9 4 9 69 5 9 7
TBF TFI 9 TBF from SERVER 9
4 224 21 4 23 4 24 4 264 25 4 27 4 28 4 29 4 314 30
TBF TFI 4 TBF from SERVER 4
2 90 2 91 2 92 2 942 93 2 95 2 96 2 97 2 992 98 2 10
TBF TFI 2 TBF from SERVER 2
TS x dedicated to ONE PDCH one PDCH shared by N users
PCU JBGPU FUNCTION
5 Annex 3PCU concept
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PDCHPCU
Gb
LLC Checks the transmission between SGSN and MS
RLC checks the trans between PCU and MS
n RLC blocks
LLC blocks
RLC blocks- token- Data - radio security
TRE /BTS
CCU
5 Annex 4PCU concept
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5 Annex 5TDMA and PDCH
> TDMA frame and GPRS physical channels
0 1 2 3 4 5 6 7
FRAME 0
0 1 2 3 4 5 6 7
FRAME 1
0 1 2 3 4 5 6 7
FRAME 2
0 1 2 3 4 5 6 7
FRAME 3
Gmsk171 1718Psk 57 57
B0 B4B1 B2 B3 B5 B6 B7 B8 B9 B10 B11
52 FRAMES then 52 TS x and 240 ms
4
F00
4
F01
4
F02
4
F04
4
F05
4
F06
4
F07
4
F08
4
F09
4
F10
4
F11
4
F12
4
F13
4
F14
4
F15
4
F16
4
F17
4
F18
4
F19
4
F20
4
F21
4
F22
4
F23
4
F24
4
F25
4
F50
4
F51
4
F03
1 PDCH12 BLOCS
PTCCH
Frame 12
Frame 38
BLOC 3
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5 Annex 6GPRS channels
> Master and Slave PDCHs
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
PDCHDOWN/UPLINK
All blocs can be used as - PDTCH- PACCH
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
MASTER PDCHDOWN /UPLINK
B0
B1
B2
All blocs can be used as- PRACH - PDTCH- PACCH
Blocs which can be used as- PBCCH
Blocs which can be used as- PAGCH- PDTCH- PACCH
Blocs which can be used as- PPCH- PAGCH- PDTCH- PACCH
▼ For each cell, it is possible to define the MINIMUM and MAXIMUM number of channels reserved for GPRS + the maximum number of channels reserved for GPRS in case of high traffic load (when the BSC sends "Load indication" to the MFS through BSCGP protocol).
▼ There are two types of PDCH : MPDCH and SPDCH
� MPDCH = Master PDCH = PBCCH + PCCCH (PPCH + PAGCH + PRACH) -> carries GPRS signaling and system information.
� SPDCH = Slave PDCH -> carries the user traffic.
▼ Benefits of the Master Channel :
� Preserves CCCH capacity for speech services
� Higher GPRS signaling capacity, in line with GPRS traffic growth
� Differentiated cell re-selection strategy between GPRS and non GPRS MS. When GPRS attached, a MS listen to PSI broadcast on PBCCH. It allows a finer tuning of GPRS re-selection algorithms, for example in hierarchical networks (C31 and C32 criteria). Otherwise, MS applies the basic Cell-reselection as in GSM Idle-Mode using the C1 and C2 GSM criteria
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B1
u3
B2
B1
un
B5
u3
B2
u3
B3
u3
B4
u3
B6
u3
B7
u3
B8
u3
B9
u6
B10
u6
B11
u2
B12
u2
B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B1
TBF from server 1
TBF from server 2TBF from server 3
TBF from server 4
TFI 1TFI 5TFI 3TFI 6
TBF server 5
TBF to server 7
TBF to server 6TFI 2 USER 3TFI 7 USER 6TFI 6 USER 2
UP
DOWN
5 Annex 7PDCH ,TBF, MAC concepts
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> PCM E1 and Bearer Channel uses and concepts
TS 1 16K X 4
TS 3 64K 64K X 1
TS 2 32K X 2
TS 4
TS 5128K 64K X 2
TS 3
TS 28
TS 31
TS 29 192K 64K X 3
2
MB
E
1
TS 1TS 2TS 3TS 4
TS 15
TS 17
TS 31
TS 18TS 19TS 20
BEARER CHANNEL =960K
BEARER CHANNEL=960K
2
MB
E
1
TS 1 64K
TS 2 64K
TS 3 64K
TS 4 64K
TS 5 64K
TS 3 64K
TS 28 64K
TS 31 64K
TS 29 64K
2
MB
E
1
5 Annex 8Different uses for E1
▼ Minimum size for a bearer channel: 1 x 64k, Maximum size for a bearer channel: 31 x 64k.
▼ One PVC per bearer channel.
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Node
15
6
9
27
PVC y
PVCn
12
5
16
DLCI Number
FRAME RELAY
PCUMFS
SGSN
5 Annex 9FRAME RELAY and PVC concepts
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Permanent Virtual Connection
FRAME
RELAY
NSVC Transmission check end to end
SGSNPCUMFS
PCM E1
BEARERCHANNEL
5 Annex 10PVC and NSVC concepts
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PCM 1
P
C
U
BC 1
BC 2
BC1
PCM 1
NSE NSEIx
PVC / NSVC
PVC / NSVC
PVC / NSVC
There is One PVC/NSVC per Bearer Channel
There is one NSE for all the PVC of one PCUPCM 2
BC 3
5 Annex 11TDMA and PDCH
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5 Annex 12 Network Mode of Operation I with Master Channel
BSC
CCCH
PCCCH
PACCH
Um
MSCVLR
SGSN
A
Gb
Gs
CS paging for GPRS-attached MS in idle state (a), o r in data transfer state (b)
CS paging for non GPRS-attached MS GPRS paging
(a)
(b)
▼ In this mode, the Gs interface is present in the core network. As far as GPRS-attached MS are concerned, the BSS receives both GPRS and circuit-switched paging messages from the Gb interface.
▼ There is paging co-ordination because all paging messages towards GPRS-attached mobile stations are sent either on the Master Channel, if present, or on the CCCH otherwise.
▼ In addition, whilst involved in a packet data transfer the GPRS mobiles receive the circuit-switched paging messages via the GPRS traffic channel currently used.
▼ NMO II :
� There is neither Gs interface nor Master Channel. There Paging coordination over the CCCH of GSM. Also, GPRS Mobile Stations operating in Class B may lose CS Paging message if they are not able to monitor CCCH at the same time.
▼ NMO III:
� In this mode, there is no Paging coordination because Gs interface is not present while the Master Channel is. Therefore, CS Paging is transmitted over CCCH when PS Paging is transmitted over PCCCH. Class C Mobile are not able to manage both type of channels.
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5 Annex 13MOBILE ONE PHASE ACCESS ON PCCH (Master PDCH)
NETWORK
Packet channel request PRACH
Packet UL assignment + polling indication PAGCH
Usf Scheduling
Packet Control ACK PACCH
RLC data bloc PDTCH
TFIPDCHUSFTA
Packet UL ACK NACK PACCH
▼ "Attach" the MS switches on (GMM protocol):
� MS sends his previous P_TMSI, otherwise a random one. The attach_request message is placed in an LLC frame with its old TLLI if its exists, or a randomly chosen TLLI if not.
▼ TLLI: This is allocated to the subscriber on his attachment to the network. In reality, the SGSN allocates the MS a P-TMSI, from which the MS and the SGSN itself derive the TLLI.
▼ The functions of the HLR:
� to supply the security triplets
� to check roaming restrictions (or ODB)
� to store the address of the current SGSN
� to initiate the deletion of data from the old SGSN
� to send subscriber data to the SGSN
▼ "Detach" proceeds as follow:
� MS to SGSN: Detach request
� SGSN to GGSN: Delete PDP context then Acknowledge
� SGSN to MS: detach accept
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Usf Scheduling
RLC data bloc PDTCH
Packet UL ACK NACK PACCH
5 Annex 14MOBILE ONE PHASE ACCESS ON CCCH (no master PDCH)
NETWORK
Channel request RACH
Immediate assignment AGCH
Packet uplink assignment + polling indication PACCH
TFI PDCH USF TA
TFI PDCH USF
Packet control ACK PACCH
▼ "Attach" the MS switches on (GMM protocol):
� MS sends his previous P_TMSI, otherwise a random one. The attach_request message is placed in an LLC frame with its old TLLI if its exists, or a randomly chosen TLLI if not.
▼ TLLI: This is allocated to the subscriber on his attachment to the network. In reality, the SGSN allocates the MS a P-TMSI, from which the MS and the SGSN itself derive the TLLI.
▼ The functions of the HLR:
� to supply the security triplets
� to check roaming restrictions (or ODB)
� to store the address of the current SGSN
� to initiate the deletion of data from the old SGSN
� to send subscriber data to the SGSN
▼ "Detach" proceeds as follow:
� MS to SGSN: Detach request
� SGSN to GGSN: Delete PDP context then Acknowledge
� SGSN to MS: detach accept
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5 Annex 15MOBILE ORIGINATING DATA TRANSFERT
BSS SGSNSTAND BY
READY
PACKET DOWNLINK ASSIGNEMENT
UL UNIDATA
RLC PDU
Paquet channel requestPaquet UL assignement
UL TBFEstablishment
RLC PDU
RLC PDU
PACKET UPLINK ACK/NACK
RLC PDU
RLC PDU
RLC PDU
UL UNIDATA
UL TBFRelease
▼ "Attach" the MS switches on (GMM protocol):
� MS sends his previous P_TMSI, otherwise a random one. The attach_request message is placed in an LLC frame with its old TLLI if its exists, or a randomly chosen TLLI if not.
▼ TLLI: This is allocated to the subscriber on his attachment to the network. In reality, the SGSN allocates the MS a P-TMSI, from which the MS and the SGSN itself derive the TLLI.
▼ The functions of the HLR:
� to supply the security triplets
� to check roaming restrictions (or ODB)
� to store the address of the current SGSN
� to initiate the deletion of data from the old SGSN
� to send subscriber data to the SGSN
▼ "Detach" proceeds as follow:
� MS to SGSN: Detach request
� SGSN to GGSN: Delete PDP context then Acknowledge
� SGSN to MS: detach accept
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5 Annex 16MOBILE TERMINATING DATA TRANSFERT
BSS SGSNSTAND BY
READY
LLC PDU
DL UNIDATA
UL UNIDATA
PACKET DOWNLINK ASSIGNEMENT
PAGING PSPacket Paging Request
channel request
Paquet UL assignement
UL TBF
DL TBF
▼ "Attach" the MS switches on (GMM protocol):
� MS sends his previous P_TMSI, otherwise a random one. The attach_request message is placed in an LLC frame with its old TLLI if its exists, or a randomly chosen TLLI if not.
▼ TLLI: This is allocated to the subscriber on his attachment to the network. In reality, the SGSN allocates the MS a P-TMSI, from which the MS and the SGSN itself derive the TLLI.
▼ The functions of the HLR:
� to supply the security triplets
� to check roaming restrictions (or ODB)
� to store the address of the current SGSN
� to initiate the deletion of data from the old SGSN
� to send subscriber data to the SGSN
▼ "Detach" proceeds as follow:
� MS to SGSN: Detach request
� SGSN to GGSN: Delete PDP context then Acknowledge
� SGSN to MS: detach accept
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5 Annex 17GMM - Combined GPRS and NSS attach with Gs (1)
HLR
Attach_request (IMSI)Triplet request ( rand kc sres )
AuthenticationUpdate_location
IMSI ↔↔↔↔ current SGSN
Insert_subscriber_data
Update_location_ack
IMSI ↔↔↔↔ TLLI + current RA + subscription data
Attach_accept (TLLI)MS ↔↔↔↔ TLLI
TLLI Established
SGSN
▼ "Attach" the MS switches on (GMM protocol):
� MS sends his previous P_TMSI, otherwise a random one. The attach_request message is placed in an LLC frame with its old TLLI if its exists, or a randomly chosen TLLI if not.
▼ TLLI: This is allocated to the subscriber on his attachment to the network. In reality, the SGSN allocates the MS a P-TMSI, from which the MS and the SGSN itself derive the TLLI.
▼ The functions of the HLR:
� to supply the security triplets
� to check roaming restrictions (or ODB)
� to store the address of the current SGSN
� to initiate the deletion of data from the old SGSN
� to send subscriber data to the SGSN
▼ "Detach" proceeds as follow:
� MS to SGSN: Detach request
� SGSN to GGSN: Delete PDP context then Acknowledge
� SGSN to MS: detach accept
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5 Annex 18GMM - Combined GPRS and NSS attach with Gs (2)
Location_Update_req (IMSI, LAI)
Insert_subscriber_data
Update_location_ack
Location_Update_accept
Update_ location (IMSI, @VLR)
IMSI ↔ current VLR
HLRSGSN MSC/VLR
▼ Location-Update-request: The SGSN determines the MSC/VLR based on the RA where the subscriber is located.
▼ At the HLR: If the MS was declared in another MSC, the HLR sends it a Cancel_Location before doing ISD to the new MSC.
▼ Attach-accept: In practice, the SGSN sends the MS the P-TMSI (and not the TLLI) and the V-TMSI (TMSI of the VLR), designated TMSI here.
▼ Once this combined-attach is done, the MS can make combined LA/RA update procedures (see GSM 03.60)..
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5 Annex 19GMM - RA update Inter-SGSN (1)
Routing_Area_update_req (RA1)
SGSN_context_req (RA1, TLLI, @SGSN2)
SGSN_context_resp (MM_ctxt, PDP_ctxt)
Update_PDP_context_req (TID, @SGSN2)
Update_PDP _context_resp
transfer of stored packets
SGSN_context_ack
newSGSN
oldSGSN
GGSN
▼ RA1: This is the mobile's previous RA The New SGSN retrieves the IP address of the old SGSN from RA1, after request to the DNS which translate RA1 into IP @ of SGSN1.
▼ SGSN_context_req:To obtain any PDP contexts and the MM contexts (IMSI, RA, cell, IMEI, etc) = all the data stored in the old SGSN concerning the MS, including the address of the GGSN related to each PDP context activated.
▼ SGSN_ctxt _ack: This message is sent only if the subscriber has PDP contexts activated. Used to inform the old SGSN that receives and stores datagrams for the MS.
▼ Update_PDP_context_req: Mainly to inform the GGSN of the address of the new current SGSN for this MS. Thus, any new packet arriving from the PDP network is routed to the new SGSN.This operation is carried out in parallel with the retrieval of the old SGSN packets, and not afterwards as the figure above seems to indicate.
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5 Annex 20 GMM - RA update Inter-SGSN (2)
cancel_location (IMSI)
cancel_location_ack
Update_location (IMSI, @SGSN 2)
Update_location_ack
insert_subscriber_data (+ack)
Routing_Area_update_accept (TLLI)
Routing_Area_update_complete
newSGSN
oldSGSN HLR
▼ ISD: = ISD (IMSI, GPRS subscription data).
▼ The tunnel (SGSN-GGSN) moves with the subscriber: The GGSN is always the same and the SGSN is variable (same TID).
▼ RA update accept: The SGSN allocates the subscriber a P-TMSI or TLLI, as mentioned (derived from the P-TMSI).
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5 Annex 21 SMS-MT on GPRS -Gd interface-
SM transfer
SRI_for_SM ([GPRS supported])
forward_SM (SM)SM transfer
report
SRI_for_SM_res (MSC@ and/or SGSN@)
forward_SM_res
report
SGSN HLR SMSGMSC
SMSSC
▼ Gd: This is the SGSN« SMS-GMSC interface.
▼ The HLR must include the option F_GPRS_002 "Support of SMS-MT over GPRS" to enable transmission of SMs to the MSs (which have this subscription option) via GPRS.
▼ SRI: If the SMS-GMSC supports GPRS, it tells the HLR so.
▼ SRI-res: The HLR sends back the following addresses:
� MS IMSI-attached only: VMSC@
� MS GPRS-attached only: SGSN@
� MS both IMSI and GPRS attached:
� SMS-GMSC does not support GPRS: One address returned according to MS preference option.
� SMS-GMSC supports GPRS: Both addresses returned. The SMS-GMSC first performs transfer through NSS or GSS according to an option. If the transfer to the MS fails (Forward-SM-res), the SMS-GMSC repeats the attempt through the second network.
▼ If the delivery through the GSS fails, the HLR sets the MNRG flag and stores the address of the SMS-GMSC.
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5 Annex 22 "Mobile User Activity" Procedure
GPRS_Attach_request
Ready_for_SM (IMSI)If MNRG=1MNRG ←←←← 0
Alert_Service_Center
Alert_Service_Center_ack
SGSN HLRSMS
GMSC
▼ Mobile user activity procedure: When the MS is reattached, the HLR indicates this to the SMS-GMSC (conventional GSM "alerting" procedure) and to all the GGSNs which had tried in vain to activate PDP contexts to this MS.
▼ The SGSN sends Ready-for-SM to the HLR before sending the “update location” message.
▼ The SMS-GMSC obviously alerts the SMSC which makes a new attempt to deliver the SM to the mobile (as in the previous slide).
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5 Annex 23 SM - PDP context activation review
NSAPI1 + PDP context 1
NSAPI2 + PDP context 2
IMSI ↔TLLI- @ MS + IP/X25- APN- QoS
(NSAPI1 + PDP context 1 + @ of GGSN1) IMSI ↔TLLI + current RA+ subscription data (NSAPI2 + PDP context 2 + @ of GGSN2)
SGSN
TID1 + PDP context 1 IMSI ↔ @ current SGSNGGSN
IMSI ↔ @ current SGSNHLR
▼ The SGSN even knows the current cell, if the mobile is in the ready state by looking at the routing over the Gb interface of the PDU originated by the MS. For further explanation, please refer to the sub-chapter “The Base Station Sub-System, The Gb interface”
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5 Annex 24 The Gb interface - Frame Relay overview
User connected to the frame relay network through a “synchronous access line”Based on semi-permanent connection, PVC
A PVC is identified on each end by a local connection identity : DLCI possible control of data loss (use of CRC )
User to network signaling is carried by a specific PVC tagged with the DLCI 0
Frame RelayFrame Relay DLCIb
access line
DLCImDLCIp
PVC 1
DLCI=0 (Sig)
DLCIpDLCIm
DLCIa PVC 2
access line
PVC 3
DLCIb
▼ Access Line = any synchronous line would do.
▼ On a FR access line, there can be a large number of PVCs (Permanent Virtual Circuits), identified each by a DLCI, (Data Link Connection Identifier), different on each side + a PVC for signaling (DLCI=0).
▼ Data Loss: all frames have a CRC field used to determine if the data (payload) is correct or not. The network discards any frame with an erroneous payload.
▼ user-to-network signaling is to check the
� local availability of the FR link ("Link Integrity Verification” procedure)
� end-to-end availability of each user's PVC ("Full Status Report" procedure)
▼ Security (redundancy): the user to the right has 2 access lines.
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FrameFrameRelayRelay
SGSN
Gb
Physicallayer
SNS
BSSGP
NSC
Gb
Frame Relay
Physicallayer
SNS
BSSGP
NSC
PCU1
Physicallayer
SNS
BSSGP
NSC
PCU2
BC1 = TSa, TSb,...BC2 = TSu, TSv,…
Bearer ChannelBC3 = TSi, TSj,…BC4 = TSx, TSy,…
BCa = all TS
BCb
PCM2
PCMa
PCMb
PCM
PCM1
5 Annex 25The Gb interface - physical layer
▼ Physical layer = PCM links from the JBGPU boards.
▼ It is best to connect the MFS and the SGSN to the FR network by two PCM links for added protection.
▼ Bearer Channel: This is N x 64 kbit/s over a 2048 kbit/s link
� N time slots on one PCM link
� FR access line.
▼ SGSN end, a BC can recover all the TSs of the PCM link to have the fastest possible access to the FR network.
▼ MFS end, on a BC, only one PVC will be declared (option chosen by Alcatel for simplicity). Therefore, for security: two BCsper BSC, each on a different PCM link (see next slides).
▼ If no FR network, the declarations of the physical and SNS layers must be the same at both ends.
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Gb
SGSN
Physicallayer
SNS
BSSGP
NSC
Gb
Frame Relay
Physicallayer
SNS
BSSGP
NSC
PCU1
BC1
Bearer Channel
BC4
BCa
Physicallayer
SNS
BSSGP
NSC
PCU2
FrameFrameRelayRelayPVC2
PVC3 PVC4
DLCIo
DLCIr
PVC
PVC1
DLCIm
DLCIp
5 Annex 26The Gb interface - SubNetwork Service layer
▼ The FR layer is part of the layer 2 in OSI model = Sub-Network Service layer (2.1). On top of this layer, and for telecom and quality of service purposes was added the Network Service Control layer (2.2).
▼ The "Bearer Channel" object of GPRS corresponds to the notion of FR access line. On a BC, there can be several PVCs(Permanent Virtual Circuits), each identified by a DLCI, which may be different at each end.
▼ Alcatel has set the limit on the BSS (MFS) side, to one PVC per BC.
▼ Several PVCs are needed:
� firstly because a PVC is used for traffic with a given BSC (and therefore several BSCs means several PVCs)
� secondly to provide security at Frame Relay level by introducing redundancy
▼ There is also, on each BC, a virtual link (with DLCI=0) for signaling with the FR switch.
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5 Annex 27The Gb interface - Network Service Control layer
Gb SGSN
Physicallayer
SNS
BSSGP
NSC
Gb
Physicallayer
SNS
BSSGP
NSC
PCU1
Physicallayer
SNS
BSSGP
NSC
PCU2
FrameFrameRelayRelay
NS-VCI=12
NS-VCI=13
NS-VCI=14
NS-VC
NS-VCI= 11
BSC1
BSC2
NSEI x
NSEI y
NSE
▼ The Network Service Control layer is used:
� To transport BSSGP frames between MFS and SGSN
� To manage FR virtual circuits (offering in particular a common identifier for the PVCs: these are the NS-VCs (Network Service layer - Virtual Circuit) thanks to a range of standard procedures : (un)block, reset and test.
� To share dynamically the UL/DL traffic (BSC to SGSN) over the existing NS-VCs of the same NSE
▼ Multiplexing scheme: 1 NS-VC = 1 PVC.
▼ NSE = Network Service Entity, identified by its NSEI, representing the packet traffic to/from a given BSC. The NSE = ΣNS-VCs dedicated to the packet traffic for one BSC. NSEI is information included in the messages between SGSN and MFS.
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Physicallayer
SNS
NSC
SGSN
Physicallayer
SNS
NSC
Gb
Physicallayer
SNS
NSC
PCU1
PCU2
BSC1
NSEBVCcellBVCI=i
BVCI=j
BVCI=k
BSC2
BVCI=m
BVCI=p
BVCI=n
BSSGP
BVCI=i, BVCI=j, BVCI=k
BVCI=m, BVCI=n, BVCI=p
5 Annex 28The Gb interface - BSS GPRS Protocol
▼ BVC = BSSGP Virtual Connection.
� One BVC for each cell (Point-To-Point BVC) to identify traffic to a particular cell within a NSE.
� One BVC-SIG (identified by BVCI0 : the fine black line) for signaling with the BSC (one per NSE).
▼ The standard also provides for BVC-PTMs. Not implemented.
▼ NSEI and BVCI are information items included in all messages between SGSN and MFS. This information must be consistent on either sides of the Gb interface.
▼ Review of the role of the BSSGP:
� to relay LLC frame (one LLC frame encapsulated into one BSSGP frame) and offer QoS over the Gb
� BVC management = management of packet traffic flow for a cell (DL flow control mechanisms, BVC supervision procedures, etc)
� MFS-SGSN signaling for LLC relay management and MS mobility management
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5 Annex 29 R97/98 QoS attributes
Precedence Precedence Name Interpretation
1 High priority Service commitments shall be maintained ahead of precedence classes 2 and 3.
2 Normal priority Service commitments shall be maintained ahead of precedence class 3.
3 Low priority Service commitments shall be maintained after precedence classes 1 and 2.
R e lia b i l i t yC la s s
G T P M o d e L L C F ra m e M o d e
L L C D a taP ro te c t io n
R L C B lo c k M o d e
T ra f f ic T y p e
1 A c k n o w le d g e d A c k n o w le d g e d P ro te c te d A c k n o w le d g e d N o n re a l- t im e tra f fic ,e rro r-s e n s it iv ea p p lic a t io n th a t c a n n o tc o p e w ith d a ta lo ss .
2 U n a c k n o w le d g e d A c k n o w le d g e d P ro te c te d A c k n o w le d g e d N o n re a l- t im e tra f fic ,e rro r-s e n s it iv ea p p lic a t io n th a t c a nc o p e w ith in f re q u e n td a ta lo s s .
3 U n a c k n o w le d g e d U n a c k n o w le d g e d P ro te c te d A c k n o w le d g e d N o n re a l- t im e tra f fic ,e rro r-s e n s it iv ea p p lic a t io n th a t c a nc o p e w ith d a ta lo ss ,G M M /S M , a n d S M S .
4 U n a c k n o w le d g e d U n a c k n o w le d g e d P ro te c te d U n a c k n o w le d g e d R e a l- t im e t ra ff ic , e rro r-s e n s it ive a p p lic a tio n th a tc a n c o p e w ith d a ta lo s s .
5 U n a c k n o w le d g e d U n a c k n o w le d g e d U n p ro te c te d U n a c k n o w le d g e d R e a l- t im e t ra ff ic , e rro rn o n -s e n s itive a p p lic a tio nth a t c a n c o p e w ith d a talo s s .
Peak Throughput Class Peak Throughput in octets per second1 Up to 1 000 (8 kbit/s).2 Up to 2 000 (16 kbit/s).3 Up to 4 000 (32 kbit/s).4 Up to 8 000 (64 kbit/s).5 Up to 16 000 (128 kbit/s).6 Up to 32 000 (256 kbit/s).7 Up to 64 000 (512 kbit/s).8 Up to 128 000 (1 024 kbit/s).9 Up to 256 000 (2 048 kbit/s).
Mean Throughput Class Mean Throughput in octets per hour1 100 (~0.22 bit/s).2 200 (~0.44 bit/s).3 500 (~1.11 bit/s).4 1 000 (~2.2 bit/s).5 2 000 (~4.4 bit/s).6 5 000 (~11.1 bit/s).7 10 000 (~22 bit/s).8 20 000 (~44 bit/s).9 50 000 (~111 bit/s).
10 100 000 (~0.22 kbit/s).11 200 000 (~0.44 kbit/s).12 500 000 (~1.11 kbit/s).13 1 000 000 (~2.2 kbit/s).14 2 000 000 (~4.4 kbit/s).15 5 000 000 (~11.1 kbit/s).16 10 000 000 (~22 kbit/s).17 20 000 000 (~44 kbit/s).18 50 000 000 (~111 kbit/s).31 Best effort.
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5 Glossary of abbreviations used A to L
> ALMAP: ALcatel MAnagement Platform
> APN: Access Point Name
> AS: Alpha Server (Compaq)
> BG: Border Gateway
> BSC: Base Station Controller
> BSS: Base Station Subsystem
> BSCGP: BSC-GPRS Protocol
> BSSGP: BSS-GPRS Protocol
> BVCI: BSSGP Virtual Connection Identifier
> CCBS: Customer Care and Billing Center
> CCU: Channel Codec Unit
> CDR: Call Detail Record
> CG: Charging Gateway
> CS: Circuit Switching
> DHCP: Dynamic Host Configuration Protocol
> DL: Down Link
> DLCI= Data Link Connection Identifier
> DNS: Domain Name System
> EDGE: Enhanced Data rates for GSM Evolution
> FUMO : Frame Unit Module
> FR: Frame Relay
> GPRS: General Packet Radio Service
> GGSN: Gateway GSN
> GMM: GPRS Mobility Management
> GR: GPRS Register
> GSL: GPRS Signaling Link
> GSM: Global System for Mobile communication
> GSN: GPRS Support Node
> GSS: GPRS Sub-System
> GTP: GPRS Tunneling Protocol
> HLR: Home Location Register
> HSCSD: High Speed Circuit-Switching Data
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5 Glossary of abbreviations used M to R
> IMSI: International Mobile Subscriber Identity
> IP: Internet Protocol
> ISDN : Integrated Service Digital Network
> ISP: Internet Service Provider
> LAN: Local Area Network
> LLC: Logical Link Control
> MAC: Medium Access Control
> MFS: Multi-Bsc Fast packet Server
> MNRG: Mobile Not Reachable for Gprs
> MS: Mobile Station
> MSC: Mobile Switching Center
> MT: Mobile Terminal
> NDL :
> NE: Network Element
> NMC: Network Management Center
> NNM: Network Node Manager
> NRPA : Network Requested PDP Context Activation
> NSAPI: Network Service Access Point Identifier
> NSC: Network Service Control layer
> NSEI: Network Service Entity Identifier
> NSS: Network Sub-System
> NS-VC: Network Service- Virtual Circuit
> NTP: Network Time Protocol
> DB : On Demand Bandwidth
> OMC: Operation & Maintenance Center
> OS: Operation System
> PAGCH: Packet- Access Grant Channel
> PCCCH: Packet- Common Control CHannel
> PCO: Protocol Configuration Options
> PCU: Packet Control Unit
> PDCH: Packet Data CHannel
> PDN: Packet Data Network
> PDP: Packet Data Protocol (IP or X25)
> PDU: Protocol Data Unit
> PPCH: Packet- Paging CHannel
> PRACH: Packet- Random Access CHannel
> PS: Packet Switching
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5 Glossary of abbreviations used R to Z
P-TMSI: Packet- Temporary Mobile Subscriber Identity
> PVC: Permanent Virtual Circuit
> P-VLR: Packet- Visitors Location Register
> QoS: Quality of Service
> RA: Routing Area
> RIP : Routing Information Protocol
> RLC: Radio Link Control
> RADIUS: Remote Authentication Dial In Use Service
> RRDTUF : Roaming Restriction Data Towards Unknown Foreign PLMN
> RRM: Radio Resource Management
> RSZ : Regional Subscription Zone
> SGSN: Serving GSN
> SM: Session Management | Short Message
> SMS: Short Message Service
> SMS-C: SMS-Center
> SNDCP: Sub Network-Dependent Convergence Protocol
> SNMP: Simple Network Management Protocol
> SNS: Sub-Network Service layer
> TBF: Temporary Block Flow
> TC: Trans Coder
> TCH: Traffic CHannel
> TCP: Transmission Control Protocol
> TDMA: Time-Division Multiplexing Access
> TFI: Temporary block Flow Identifier
> TID: Tunnel IDentity
> TLLI: Temporary Logical Link Identity
> TMN: Telecommunication Management Protocol
> TS: Time Slot
> UDP: User Datagram protocol
> UL: Up Link
> UMTS: Universal Mobile Transmission System
> WAP: Wireless Application Protocol
> WAN: Wide Area Network
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5 Main GPRS Standards
> EN 301 344 (GSM 03.60) GPRS Service description stage 2
> TS 101 350 (GSM 03.64) Overall description of the GPRS radio interface, stage 2
> GSM 04.60 GPRS MS-BSS interface. RLC/MAC protocols
> TS 101 351 (GSM 04.64) MS-SGSN Logical Link Control layer
> TS 101 297 (GSM 04.65) MS-SGSN Sub-Network-Dependent Convergence Protocol layer
> TS 101 356 (GSM 07.60) MS supporting GPRS
> GSM 08.18 BSS-SGSN BSS GPRS Protocol (BSSGP)
> EN 301 347 (GSM 09.60) GPRS Tuneling Protocol (GTP) across the Gn and Gp interface
> TS 101 348 (GSM 09.61) GPRS inter-working between PLMN and PDN
> TR 10.18 (GSM 10.18) O&M in GPRS
> TS 101 393 (GSM 12.15) GPRS charging
▼ New ETSI standard designations:
� EN = ETSI Standard
� TS = Technical Specification
� TR = Technical Report
� TS and TR are less constraining than a true standard (EN).
▼ The designation GSM xx.xx remains valid.