modul 7 gprs operation
DESCRIPTION
Explain and describe about GPRS Technology.TRANSCRIPT
GSM-GPRS Operation
GPRS Procedures And Operations
Modul 7
2
Agenda
1. Introduction to GPRS• Apakah itu GPRS ?
• Pengkodean di GPRS
• Kelas-kelas MS pada GPRS
• Aplikasi-aplikasi GPRS
2. Bagaimana GPRS bekerja?3. Karakteristik GPRS 4. Aplikasi-Aplikasi GPRS 5. Keterbatasan GPRS6. Arsitektur GPRS7. Fungsi Elemen
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MSC
LocalAreaNetwork
Server
Router
Corporate 1
LocalAreaNetwork
Server
Router
Corporate 2
GPRSINFRASTRUCTURE
BorderGateway (BG)
Serving GPRSSupport Node(SGSN)
HLR/AuCEIR
BSC
BTS
Um
SMSC
Firewall
Firewall
Gateway GPRSSupport Node(GGSN)
GPRS Logical Architecture
Legal InterceptionGateway (LIG)
Firewall
Inter-PLMNnetwork
Datanetwork(Internet)
Datanetwork(Internet)
PSTNNetwork
SS7Network
GPRSbackbonenetwork
(IP based)
Billing System
Charging Gateway (CG)
Domain NameServer (DNS)
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Logical architecture: Interfaces
other PLMN
MSC/VLR HLR
EIR
SGSN
GGSN
GGSN
SGSN
PDN TE
SMS-GMSCSMS-IWMSC
MS BSSGiGn
Gn Gp
Gb
Gd
Um
GcGrGs
Gf
CE
D
A
Signalling & Data Transfer
Signalling
GPRS Interfaces
5
Functional view of GPRS
Local areanetwork
Server
Router
Local areanetwork
Server
Router
Corporate 2
Corporate 1
Intra-PLMNbackbonenetwork(IP based)
Serving GPRSSupport Node(SGSN)
Point-To-MultipointServiceCenter (PTM SC)
Gateway GPRSSupport Node(GGSN)
GPRS INFRASTRUCTURE
HLR/AuC
MSC
BSCBTS PacketnetworkPSTN
PacketnetworkSS7Network
Packetnetwork
Datanetwork(Internet)
Packetnetwork
Datanetwork(X.25)
Packetnetwork
Inter-PLMNBackbonenetwork
Border Gateway (BG)
Gb
Gr Gd
Gi.IP
Gi.X.25
Firewall
Firewall
Firewall
UmR/S
SMS-GMSC
Gr Gd
Gs
Gs
Gp
Gn
Gn
EIR
MAP-F
SGSN = Serving GPRS Support NodeGGSN = Gateway GPRS Support NodeNMS = Network Management SystemBG = Border GatewayCG = Charging GatewayFW = FirewallLIG = Legal Interception Gateway
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GPRS network seen by an other data network
L ocal areanetwork
R outerC orporate 2
L ocal areanetwork
R outer
C orporate 1P ac ketnetwo rkDatanetwork(Internet)
G P R S S UB NE T W O R K
S UB NE TWO R K155.222.33.XXX
S UB NE T W O R K131.44.15.XXX
S UB NE T W O R K191.200.44.XXX
HOS T191.200.44.21
HO S T131.44.15.3
HO S T155.222.33.55
"R outer"
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Data transfer
Localareanetwork
Server
Router
SGSN
GGSN
IPROUTER
BSCBTS
GPRSbackbonenetwork(IP based)
SGSN
GGSN
IPROUTER
BSC BTS
GPRSbackbonenetwork(IP based)
Packetnetwork
Inter-operatorbackbonenetwork
Packetnetwork
Datanetwork(Internet)
Corporate
HOME GPRSNETWORK
VISITEDGPRSNETWORK
case 1
case 2
case 3
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GTP Container
User packetTunnel ID:
IMSI…
THE GTP PACKETIP (+TCP/UDP)
Who is the user?
To which GSN?
GSN IP-address
E.g. a TCP/IP packet carrying e-mail
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Protokol Di GPRS
Pada Jaringan GPRS, data harus dilewatkan ke stack protokol yg berbeda sebelum diterima oleh alamat tujuan
Protokol ini sudah integrated dielemen GPRS yg sifatnya sudah terproteksi dan pengirimannya terjamin
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Protokol Pada MS
Internet Protocol dan X.25 monitor routing informasi pelanggan di jar backbone GPRS
Subnetwork Dependent Convergence Protocol (SNDCP) bertanggung jawab dlm kompresi dan segmentasi data ke unit2 kecil
Logical Link Control Protocol (LLC) menjamin koneksi aman (reliable and ciphered connection) ke SGSN
Radio Link Control Protocol (RLC) memberikoneksi air interface utk transmisi data. Jika ada error transmisi dpt diketahui pd saat data sampai direceiver
Medium Access Control Protocol (MAC) mengontrol terjadinya koneksi di air interface mulai dari assignment dan acknowledgment
GSM Radio Frequency protocol layer bertanggung jawab utk memberikan saluran fisik berupa air interface
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Protokol di BSS
Base Station Subsystem GPRS Protocol (BSSGP) bertanggung jawab utk routing ke SGSN
SGSN mempunyai kemampuan utk memilih rute data alternatif Network Service Protocol (NS) BSSGP Packet Data Units dibawa ke
Service Access Point pada layer jaringan Protokol ketiga dan terakhir di BSS : L1 bis Protocol
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Protocol Di SGSN
GPRS Tunneling Protocol (GTP) IP address GPRS backbone network, bertanggung jawab thd semua pesan GPRS, signaling dan data pelanggan melalui tunneled transmission antar GPRS Support Nodes. Transmisinya tdk bisa diinterferensi oleh user lain
User Datagram Protocol (UDP) digunakan dlm transmisi tunneled PDU ketika aplikasi tdk aktif di sisi receiver
Transmission Control Protocol (TCP) reliable transmission.
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BTS BSC
SGSN
GGSN Intranet
GGSNInternet
CG
BillingSystem
RouterServer
LocalAreaNW
CorporateGPRS Core
Network
BG
InterPLMNNetwork LIG
GPRS Core NetworkLogical Network Elements
SGSN = Serving GPRS Support NodeGGSN = Gateway GPRS Support NodeNMS = Network Management SystemBG = Border GatewayCG = Charging GatewayFW = FirewallLIG = Lawful Interception Gateway
FW
FW
NMS
DNS
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GPRS Mobility Management (GMM)
Procedures that take care of the mobility of the user are called GPRS Mobility Management (GMM). The GMM procedures are similar to the mobility management for circuit switched users.
One of a GMM procedure is the GPRS attach procedure. When a GPRS terminal is powered on, it sends an 'attach' message to the network.
The SGSN authenticates the user before attaching the terminal to the GPRS network. Once a subscriber has attached to the network, logical connection is established
between the MS, the SGSN, and the HLR.
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Session Management (SM) Procedures that handle the user connection to the
external data networks are called Session Management (SM)
The procedure to establish a connection to an external data network is called “PDP context activation” procedure. Hereby, a connection is established between the MS and GGSN via the SGSN.
The GPRS MS has to register with the PLMN for the first time, much in the same way as a normal GSM MS. The difference between the GPRS and GSM MS phone is that it has to update location information in the SGSN as well.
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Subcriber information, Information Elements and Location
Type of info What info Where
Identity IMSITMSIIP address
SIM, HLR, VLR, SGSNSGSN, MSMS, SGSN, GGSN
Location VLR addressLocation areaServing SGSNRouting area
HLRSGSN, VLRHLR, VLRSGSN
Services Basic services, supplementary services, circuit switched bearer services, GPRS service information
Basic services, supplementary services, CS bearer services
GPRS service information
HLRVLR
SGSN
Authentication data Ki, algorithmsTriplets
SIM, ACVLR, SGSN
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Routing Area
A routing area is defined as one or more cells with a maximum size of number of cells in one location area that is used for paging GPRS subscribers.
SGSN-1
BSC-1
RA-1 RA-3
SGSN-2
BSC-2
RA-2
LA-1 LA-3
Cell Routing area Location area MSC coverage areaCell Routing area SGSN coverage area
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Routing Area Identity (RAI) The RAI is defined by the operator and is broadcast by the system.
The GPRS MS monitors the RAI when changing cells to see if a RA border has been crossed. If the RA changes, it is the responsibility of the MS to initiate the RA update procedure. The structure of the RAI is:
Where RAC is Routing Area Code The RAI is LAI + RAC. The RAI is of fixed length - 15 digits.
RAI = MCC + MNC + LAC + RAC
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Mobility Management States A GPRS MS has one of three mobility
management states: The Idle state is used when the MS is passive
(not GPRS attached). A MS is in Ready state and in the active phase
when it is transmitting or has just been transmitting data.
The Standby state is entered when the subscriber has ended an active phase but is still attached to the network.
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MS In Idle State
RA-1
VLR-1
HLR
SGSN-1BSC
IMSI 244...VLRSGSN
IMSILAISGSN ?
IMSI ?RA ?Cell ?
LA-1
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MS In Ready State
RA-1
VLR-1
HLR
SGSN-1BSC
IMSI 244...VLR VLR-1SGSN SGSN-1
IMSI 244...LAI LA-1SGSN SGSN-1
IMSI 244...RAI RA-1CellCell cellcell--11
LA-1
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MS In Standby State
RA-1
VLR-1
HLR
SGSN-1BSC
IMSI 244...VLR VLR-1SGSN SGSN-1
IMSI 244...LAI LA-1SGSN SGSN-1
IMSI 244...RAI RA-1CellCell ??????????
LA-1
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Location Management The location management procedures are
a group of mobility management procedures that we use to handle the changing of a cell or a routing area or a SGSN coverage area. Information in the databases has to be modified during these procedures.
Periodic routing area update is used for checking that a MS that has not done any routing area updates for some period of time is still reachable.
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Routing Area Update
Two types of routing area updates: Inter-SGSN routing area update:
If the old and new routing areas are managed by different SGSNs, an inter-SGSN routing area update is performed. The old SGSN forwards user packets to the new SGSN.
Intra-SGSN routing area update:If the old and the new routing area belong to the same SGSN, an intra-SGSN routing area update is performed
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Intra SGSN RA Update Procedure
HLR
SGSN
BSC
LA-1
GGSN
1
New RA
(1)The MS requests a routing area update
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Session Management Session management collectively refers to a set of procedures
for the activation, deactivation, and modification of a data session between a MS and an external network
In order to set up data sessions, the GPRS system provides a group of functions for associating a MS with an address (typically the IP address) and for releasing this association.
These are called PDP context functions. The resulting PDP context can also be modified. The MS can use the PDP context functions only when in Standby or Ready state.
The MS can use various kinds of IP addresses. The home network operator may assign a static IP address to a MS permanently. Another option for the operators is to assign a dynamic IP address to a MS during PDP context activation
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PDP Context Activation
MS SGSN GGSN
2. SecurityFunctions
1. Activate PDPContext Request
DNSServer
DNSinquiry
3. Create PDPContext Request
4. Create PDPContext Response
Connection establishment
with PDN
5. Activate PDPContext Accept
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PDP Context Include : PDP type, that is, IP connection or X25
connection. Access point name (APN): a symbolic name for
a network interface to an external network in the GGSN. One GGSN could have several different access points to access different networks.
IP address (empty = dynamic), which is also referred to as PDP address.
QoS parameters
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Charging In GPRS
Charging data is collected fromSGSN and GGSN
Collected charging information:
- Mobility management data- Duration of PDP context - Data volume uplink/downlink- Usage of external networks (= Access Point)- SGSN & GGSN address
BTS BSC
SGSN
GPRS Backbone IP Network
GGSN
Internet
Service
CG
Charging Gateway
BC
Billing Center
Specific GTP' protocol used to carry CDRs from SGSN/GGSN to Charging Gateway
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Charging….
CDRs produced by GGSN
CDRs produced by SGSN
CG
S-CDRsM-CDRsSMS-CDRs
Internet
GGSN
OperatorIP backbone
SGSN
CG
Internet
GGSN
OperatorIP backbone
SGSN
G-CDRs
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Security In GPRS The GPRS system has inherited the GSM Phase 2
security functions: Authentication of the subscribers IMEI checking User identity confidentiality (TMSI, now P-TMSI in GPRS) Ciphering of the data traffic between the MS and the
SGSN. The additional GPRS security features are:
Private IP addressing in the GPRS backbone Ciphered links and authentication between nodes in the
GPRS backbone Screening of packets coming from the external networks.
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Authentication…
MS is authenticated Ciphering key selected Equipment identity is
optionally checked Location updated to HLR
and VLR
SGSN interfaces HLR for GPRS attachBTS BSC
SGSN
GGSN
GPRS Backbone IP Network
SS7
HLRMSC/VLR
Intranet
Internet
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Security….
Addressing in the backbone, external networks (access point), and the MS
SGSN GGSNDNS
Internet
BTS BSC
10.1.1.110.1.1.210.1.1.3
10.1.1.4GPRS BackboneGPRS Backbone
FW
123.45.67.88
123.45.0.0/16
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Security…. Interconnecting GPRS networks of different
PLMNs with link physically secure
SGSN SGSN GGSN
Internet
Toward other sites
site 1Security Router
SGSN SGSN SGSN
site 2
OperatorPrivate IP
network
SecureLinks
Security Router
Link physically
secure
GGSN site
Router
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Security….
Subscription- and network-controlled screening
In ternet
O perator screening
Subscriptioncontrolled screening
Address:From
172.60.10to
172.60.20
Address:From
172.60.21to
172.60.50
Address:From
172.60.10to
172.60.50
F irew allF irew all
F irew all
Businessscreening
basicscreening
G G SN
G G SN
APN =Business
APN =Basic
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Precedence class (priority)The service precedence indicates the priority of maintaining a service under abnormal conditions such as network congestion. Packets may be discarded according to precedence level. The following precedence levels are : Precedence Class 1 (High precedence):
Service commitments will be maintained ahead of all other precedence levels.
Precedence Class 2 (Normal precedence):Service commitments will be maintained ahead of low priority users.
Precedence Class 3 (Low precedence):Service commitments will be maintained after the high and normal priority commitments have been fulfilled.
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Delay Class The delay parameter defines the maximum values for the
mean delay and 95% delay to be incurred by data passing through the GPRS network. The delay parameter defines the delay incurred by data packets within the GPRS network.
Size 120 octets 1024 octets
Class Mean Delay 95% Mean Delay 95%
1 (Predictive) 0.5 s 1.5 s 2 s 7 s
2 (Predictive) 5 s 25 s 15 s 75 s
3 (Predictive) 50 s 250 s 75 s 375 s
4 (Best Effort) Not specified
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Reliability Class define the probability of: Lost data Duplication of data Data arriving out of sequence Corruption of data. The reliability class specifies the requirements of
the various network protocol layers. The combinations of the GTP, LLC, and RLC transmission modes support the reliability class performance requirements.
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The throughput class indicates the data throughput requested by the user. Throughput is defined by two negotiable parameters: Maximum bit rate Mean bit rate. This includes, for example for "bursty"
transmissions, the periods in which no data is transmitted. The maximum and mean bit rates can be represented by a
parameter known as the Information Transfer Rate.
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The maximum bit rate is measured in octets per second at the Gi and R reference points. It specifies the maximum rate at which data is expected to be transferred across the network for an individual PDP context. There is no guarantee that this maximum rate will be achieved or sustained for any time period as this depends upon the MS capability and available radio
resources.
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The mean bit rate (throughput) is measured at the Gi and R reference points in units of octets per hour. It specifies the average rate at which data is expected to be transferred across the GPRS network during the remaining lifetime of an activated PDP context. The network may limit the subscriber to the negotiated mean bit rate (for example, for flat rate charging), even if additional transmission capacity is available.
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Conclusion
1. The messages that are sent between various components of the GPRS network are collectively referred to as GPRS traffic. To manage this traffic in an orderly manner, one needs a set of traffic management procedures.
2. Procedures that handle mobility of user are called GPRS Mobility Management (GMM). Procedures that handle the user connection to the external networks are called Session Management (SM).
3. There are two phases in connecting a GPRS terminal to the network:
Connection to the GPRS(SGSN) network or GPRS attach Connection to the external network: PDP context
activation
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4. A routing area is defined as one or more cells with a maximum size of one location area that is used for paging GPRS subscribers. An SGSN can have a number of RA associated with it.
5. An MS can have: Static IP address: the user always has the same
IP address, or Dynamic IP address: the network allocates the
user a different IP address for each session.
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6. In Idle state the MS is not attached to the GPRS. No information about the subscriber is known.
7. A MS is in Ready state and in the active phase when it is transmitting or has just been transmitting.
8. The MS enters Standby state when it has ended an active phase. MS is not transmitting anything.
9. The MS performs a cell update when it changes cell within a routing area in Ready mode.
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10. When the MS changes cell between the different routing areas, it performs a routing area update.
11. The GPRS core network uses private, unregistered IP addresses. The GGSN maps (or translates) the private addresses into one (or more) registered public IP addresses and port pairs. The MS uses one of the public IP addresses.
12. GGSN and SGSN generate CDRs. The CDRs are transferred to the charging gateway. The charging gateway interfaces to the Billing Centre.
13. GPRS has inherited the GSM Phase 2 security features. Additional GPRS specific security features are implemented: private IP addressing in the GPRS backbone, ciphered links and authentication between nodes in the GPRS backbone, screening of packets coming, etc.
GSM-GPRS Operation
End of Section 7
GPRS Procedures And Operations