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Gprs
1. General Packet Radio Service
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 1
(GPRS)
Petteri Lappalainen
23.11.1998
IP Tech School
Seminar Presentation
Based on the material by
Tuomas Niemelä (-97), Hannu H. Kari (-98) and ETSI
3. NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 3
Contents
1. Introduction to GPRS
• What is GPRS ?
• GPRS characteristics
• Applications
2. GPRS architecture
• Network elements
3. GPRS Operations
• Radio interface
resource reservation
• Security operations
• Connecting to GPRS
• Data transfer
• Mobility management
• Interworking with GSM
services
4. Special issues
• SMS
• Charging
• O&M
• Supplementary services
• QoS
• Performance
5. GPRS business view
• What must be invested…
• How to make money with
GPRS
• Users' benefits of GPRS
• Business model
6. GPRS specifications
4. 1. Introduction to GPRS
1.1. What is GPRS ?
1.2. GPRS access interfaces and reference points
1.3. How is GPRS seen by external networks and GPRS users
1.4. Air interface resources
1.5. GPRS characteristics
1.6. Applications
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 4
5. • Part of GSM phase 2+
• General Packet Radio Service
• General -> not restricted to GSM use (DECT ?, 3rd
generation systems ?)
• Packet Radio -> enables packet mode communication
over air
• Service, not System -> existing BSS (partially also NSS)
infrastructure is used
• Requires many new network elements into NSS
• Provides connections to external packet data networks
(Internet, X.25)
•Main benefits
• Resources are reserved only when needed and charged
accordingly
• Connection setup times are reduced
• Enables new service opportunities
NOKIA TELECOMMUNICATIONS
1.1. What is GPRS ?
IP TECH SCHOOL seminar / 23.11.1998 / slide 5
6. 1.2. GPRS access interfaces and
NOKIA TELECOMMUNICATIONS
reference points
IP TECH SCHOOL seminar / 23.11.1998 / slide 6
Gi reference point
GPRS network 1
GPRS network 2
PDNs or
TE MT other networks
Gp
R reference point Um
MS
• GPRS provides packet switched connections from MS
to packet data networks (PDN)
• Different operator’s GPRS networks are connected
through Gp interface
7. 1.3. How is GPRS seen by external
networks and GPRS users?
C o r p o r a t e 1
NOKIA TELECOMMUNICATIONS
R o u t e r
IP TECH SCHOOL seminar / 23.11.1998 / slide 7
R o u t e r
L o c a l
a r e a
n e t w o r k
C o r p o r a t e 2
L o c a l
a r e a
n e t w o r k
G P R S
S U B N E T W O R K
S U B N E T W O R K
1 5 5 . 2 2 2 . 3 3 . X X X
P a c k e t
n e t w o r k D a t a
n e t w o r k
( In t e r n e t )
S U B N E T W O R K
1 3 1 . 4 4 . 1 5 . X X X
S U B N E T W O R K
1 9 1 . 2 0 0 . 4 4 . X X X
H O S T
1 9 1 . 2 0 0 . 4 4 . 2 1
H O S T
1 3 1 . 4 4 . 1 5 . 3
H O S T
1 5 5 . 2 2 2 . 3 3 . 5 5
" R o u t e r "
8. 1.4. Air interface resources
GPRS "steals" any TCH Capacity
capacity not used by CS
traffic
14
12
10
8
6
4
2
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 8
14
12
10
8
6
4
2
0
Free
1:00 PM 1:15 PM 1:30 PM 1:45 PM
TCH
An example of occupied TCH
capacity by CS traffic during
busy hour with n% blocking
0
3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00
TCH
Capacity occupied by CS traffic
9. 1.5. GPRS characteristics
GPRS uses packet switched resource allocation
• resources allocated only when data is to be
sent/received
Flexible channel allocation
• one to eight time slots
• available resources shared by active users
• up and down link channels reserved separately
• GPRS and circuit switched GSM services can use
same time slots alternatively
Traffic characteristics suitable for GPRS
• Intermittent, bursty data transmissions
• Frequent transmissions of small volumes of data
• Infrequent transmission of larger volumes of data
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 9
10. • Standard data network protocol based
• IP based applications
• X.25 based applications
• GPRS specific protocol based
• Point-to-point applications
• Point-to-multipoint applications
• SMS delivery (GPRS as a bearer for SMS)
NOKIA TELECOMMUNICATIONS
1.6. Applications
– WWW, FTP, Telnet, ...
– Any conventional TCP/IP based applications
– Packet Assembly/Disassembly (PAD) type approach
– Toll road system, UIC train control system
– Weather info, road traffic info, news, fleet management
IP TECH SCHOOL seminar / 23.11.1998 / slide 10
11. 2.1. Interfaces, reference points and network elements
2.2. Functional view on GPRS
2.3. Subscription of GPRS service
2.4. New network elements
2.4.1. GGSN
2.4.2. SGSN
2.4.3. Other elements
2.4.4. GPRS backbones
2.5. GPRS Mobile classes
2.6. MS multislot capabilities
NOKIA TELECOMMUNICATIONS
2. GPRS architecture
IP TECH SCHOOL seminar / 23.11.1998 / slide 11
12. 2.1. Interfaces, reference points and
MSC/VLR
Gd
Gr
A
TE MT BSS PDN TE
R Um
Signalling Interface
NOKIA TELECOMMUNICATIONS
network elements
MAP-H MAP-C
IP TECH SCHOOL seminar / 23.11.1998 / slide 12
MAP-F
Gi
Gn
Gb
Gc
MAP-D
Gs
SGSN
Gp
GGSN
Signalling and Data Transfer Interface
HLR
Other PLMN
SM-SC
SMS-GMSC
SMS-IWMSC
GGSN
EIR
13. 2.2. Functional view on GPRS
NOKIA TELECOMMUNICATIONS
BTS BSC Packet
IP TECH SCHOOL seminar / 23.11.1998 / slide 13
Corporate 1
Server
Local
area
network
Router
Corporate 2
Server
Local
area
network
Router
Intra-PLMN
backbone
network
(IP based)
Serving GPRS
Support Node
(SGSN)
Point-To-
Multipoint
Service
Center
(PTM SC)
GPRS
INFRASTRUCTURE
Gateway GPRS
Support Node
(GGSN)
HLR/AuC
MSC
nPeStwToNrk
Packet
SnSet7work
Network
Data
Packet
network
network
(Internet)
Data
network
(X.25)
Packet
network
Packet
network Inter-PLMN
Backbone
network
Border
Gateway (BG)
Gb
Gr Gd
Gi.IP
Gi.X.25
Firewall
Firewall
Firewall
R/S Um
SMS-GMSC
Gr Gd
Gs
Gs
Gp
Gn
Gn
EIR
MAP-F
14. Assignment of functions to general
logical architecture
Function MS BSS SGSN GGSN HLR
Network Access Control:
Registration X
Authentication and Authorisation X X X
Admission Control X X X
Message Screening X
Packet Terminal Adaptation X
Charging Data Collection X X
Packet Routeing & Transfer:
Relay X X X X
Routeing X X X X
Address Translation and Mapping X X X
Encapsulation X X X
Tunnelling X X
Compression X X
Ciphering X X X
Mobility Management: X X X X
Logical Link Management:
Logical Link Establishment X X
Logical Link Maintenance X X
Logical Link Release X X
Radio Resource Management:
Um Management X X
Cell Selection X X
Um-Tranx X X
Path Management X X
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 14
15. 2.3. Subscription of GPRS
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 15
service (1/2)
Subscription storage: HLR
Supports Multiple Subscriber Profile (MSP)
Mobile identification: IMSI
One or several PDP addresses per user
• Each subscribed configuration contains
• PDP type (e.g., IP, X.25)
• PDP address (static, e.g. 128.200.192.64)
• Subscribed QoS (level 1…4)
• Dynamic address allowed
• VPLMN address allowed
• GGSN address
• Screening information (optional)
16. 2.3. Subscription of GPRS
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 16
service (2/2)
Subscription is copied from HLR to SGSN during GPRS
Attach
Part of PDP context is copied to relevant GGSNs when a
PDP address is activated
Possible PDP address allocation alternatives
• Static address allocated from HPLMN
• Dynamic address allocated from HPLMN
• Dynamic address allocated from VPLMN
HPLMN operator specifies which alternatives are possible
17. 2.4.1. Gateway GPRS Support Node
GGSN
• Typically located at one of the MSC sites
• One (or few) per operator
•Main functions
• Interface to external data networks
• Resembles to a data network router
• Forwards end user data to right SGSN
• Routes mobile originated packets to right destination
• Filters end user traffic
• Collects charging information for data network usage
• Data packets are not sent to MS unless the user has
activated the PDP address
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 17
18. 2.4.2. Serving GPRS Support Node
SGSN
• Functionally connected with BSC, physically can be at
MSC or BSC site
• One for few BSCs or one (or few) per every BSC
• One SGSN can support BSCs of several MSC sites
•Main functions
• Authenticates GPRS mobiles
• Handles mobile’s registration in GPRS network
• Handles mobile’s mobility management
• Relays MO and MT data traffic
• TCP/IP header compression, V.42bis data
compression, error control MS- SGSN (ARQ)
• Collect charging information of air interface usage
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 18
19. BG (Border Gateway)
• (Not defined within GPRS)
• Routes packets from SGSN/GGSN of one operator to a SGSN/GGSN of an
other operator
• Provides protection against intruders from external networks
DNS (Domain Name Server)
• Translates addresses from ggsn1.oper1.fi -format to 123.45.67.89 format
(i.e. as used in Internet)
Charging Gateway
• Collects charging information from SGSNs and GGSNs
PTM-SC (Point to Multipoint -Service Center)
• PTM Multicast (PTM-M): Downlink broadcast; no subscription; no ciphering
• PTM Group call (PTM-G): Closed or open groups; Down/up -link; ciphered
• Geographical area limitation
NOKIA TELECOMMUNICATIONS
2.4.3. Other elements
IP TECH SCHOOL seminar / 23.11.1998 / slide 19
20. 2.4.4. GPRS backbones
Enables communication between GPRS Support Nodes
Based on private IP network
• IPv6 is the ultimate protocol
• IPV4 can be used as an intermediate solution
Intra-PLMN backbone
• Connects GPRS Support Nodes of one operator
• Operator decides the network architecture
• LAN, point-to-point links, ATM, ISDN, ...
Inter-PLMN backbone
• Connects GPRS operators via BGs
• Provides international GPRS roaming
• Operators decide the backbone in the roaming agreement
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 20
21. 2.5. GPRS mobile types
Class A:
• Simultaneous GPRS and conventional GSM operation
• Supports simultaneous circuit switched and GPRS data transfer
Class B:
• Can be attached to both GPRS and conventional GSM services
simultaneously
• Can listen circuit switched and GPRS pages (via GPRS)
• Supports either circuit switched calls or GPRS data transfer but
not simultaneous communication
Class C:
• Alternatively attached in GPRS or conventional GSM
• No simultaneous operation
• ‘GPRS only’ mobiles also possible (e.g. for telemetric
applications)
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 21
23. 3.1 Security: Basic security rules
• Authentication, key management, ciphering
3.2 GPRS attach
3.3 Data transmission
• MO, MT, MO+MT
3.4 Mobility management
3.5 Interworking with GSM services
NOKIA TELECOMMUNICATIONS
3. GPRS operations
IP TECH SCHOOL seminar / 23.11.1998 / slide 23
24. 3.1. Security: Based on GSM phase 2
Authentication
• SGSN uses same principle as MSC/VLR:
• Get triplet, send RAND to MS, wait for SRES from MS, use Kc
• MS can’t authenticate the network
Key management in MS
• Kc generated same way from RAND using Ki as in GSM
Ciphering
• Ciphering algorithm is optimized for GPRS traffic (‘GPRS -
A5’)
• Ciphering is done between MS and SGSN
User confidentiality
• IMSI is only used if a temporary identity is not available
• Temporary identity (TLLI) is exchanged over ciphered link
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 24
25. GPRS Attach function is similar to IMSI attach
• Authenticate the mobile
• Generate the ciphering key
• Enable the ciphering
• Allocate temporary identity (TLLI)
• Copy subscriber profile from HLR to SGSN
After GPRS attach
• The location of the mobile is tracked
• Communication between MS and SGSN is secured
• Charging information is collected
• SGSN knows what the subscriber is allowed to do
• HLR knows the location of the MS in accuracy of SGSN
NOKIA TELECOMMUNICATIONS
3.2. GPRS Attach
IP TECH SCHOOL seminar / 23.11.1998 / slide 25
26. 3.3. Data transfer: Basic rules (1/4)
• SGSN:
• Does not interpret user data, except
• SGSN may perform TCP/IP header compression
• Does not interpret source or destination addresses
• Sends all packets to specified GGSN that handles
the PDP context
• GGSN:
• Performs optional filtering
• Decides where and how to route the packet
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 26
27. Mobile originated (left when MS in HPLMN, right when in
VPLMN, no filtering/screening)
H P L M N V P L M N
NOKIA TELECOMMUNICATIONS
3.3. Data transfer (2/4)
IP TECH SCHOOL seminar / 23.11.1998 / slide 27
S e r v e r
B G
L o c a l
a r e a
n e t w o r k
R o u t e r
S G S N
B G
G G S N
B T S B S C
I n t r a - P L M N
b a c k b o n e
n e t w o r k
( I P b a s e d )
S G S N
G G S N
B S C B T S
I n t r a - P L M N
b a c k b o n e
n e t w o r k
( I P b a s e d )
P a c k e t
n e t w o r k
I n t e r - P L M N
b a c k b o n e
n e t w o r k
D P a a t c a
k e t
n n e e t w t w o o r k
r k
( I n t e r n e t )
C o r p o r a t e
28. Mobile terminated (left when MS in HPLMN, right when in
VPLMN, with/without filtering/screening)
H P L M N V P L M N
NOKIA TELECOMMUNICATIONS
3.3. Data transfer (3/4)
IP TECH SCHOOL seminar / 23.11.1998 / slide 28
S e r v e r
B G
L o c a l
a r e a
n e t w o r k
R o u t e r
S G S N
B G
G G S N
B T S B S C
I n t r a - P L M N
b a c k b o n e
n e t w o r k
( I P b a s e d )
S G S N
G G S N
B S C B T S
I n t r a - P L M N
b a c k b o n e
n e t w o r k
( I P b a s e d )
P a c k e t
n e t w o r k
I n t e r - P L M N
b a c k b o n e
n e t w o r k
D P a a t c a
k e t
n n e e t w t w o o r k
r k
( I n t e r n e t )
C o r p o r a t e
29. Mobile originated and terminated (left MSs in same
PLMN, right MSs in different PLMN)
H P L M N V P L M N
S G S N
NOKIA TELECOMMUNICATIONS
3.3. Data transfer (4/4)
IP TECH SCHOOL seminar / 23.11.1998 / slide 29
S e r v e r
B G
L o c a l
a r e a
n e t w o r k
R o u t e r
S G S N
B G
G G S N
B T S B S C
In t r a - P L M N
b a c k b o n e
n e t w o r k
( I P b a s e d )
S G S N
G G S N
B S C B T S
I n t r a - P L M N
b a c k b o n e
n e t w o r k
( I P b a s e d )
P a c k e t
n e t w o r k I n t e r - P L M N
b a c k b o n e
n e t w o r k
D P a a t c a
k e t
n n e e t w t w o o r k
r k
( I n t e r n e t )
C o r p o r a t e
B T S B S C
30. 3.4. Mobility management (1/3)
Instead of Location Area, GPRS uses Routing Areas to
group cells. RA is a subset of LA.
• IDLE:
• MS is not known by the network (SGSN)
• STANDBY:
• MS’s location is known in accuracy of Routing Area
• MS can utilize DRX (to save battery)
• MS must inform its location after every Routing
Area change (no need to inform if MS changes
from one cell to another within same Routing Area)
• Before the network can perform MT data transfer
MS must be paged within the Routing Area
• MS may initiate MO data transfer at any time
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 30
31. 3.4. Mobility management (2/3)
• READY:
• MS’s location is known in accuracy of cell
• MS must inform its location after every cell change
• MS can initiate MO data transfer at any time
• SGSN does not need to page the MS before MT
data transfer
• MS listens continuously GPRS PCCCH channel
• DRX in READY state is optional
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 31
32. 3.4. Mobility management (3/3)
Mobility management messages:
• Cell update (implicit, with any message)
• When MS changes the cell within a Routing Area in
READY state
• Routing Area update
• When MS changes the cell between two Routing
Areas in READY or STANDBY state
• Two types of Routing Area Updates (from MS’s point
of view only one type)
• Periodic Routing Area updates are applicable
NOKIA TELECOMMUNICATIONS
– Intra-SGSN Routing Area Update
– Inter-SGSN Routing Area Update
IP TECH SCHOOL seminar / 23.11.1998 / slide 32
33. 3.5. Interworking with GSM services
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 33
(1/3)
• GPRS can interwork with GSM services through Gs-interface
• If no Gs interface exists:
• Type of the location update procedure is indicated
by the network in the response message to MS
• Effects on different MS classes if Gs does not exist:
• A-class mobiles must use conventional GSM
services via normal GSM channels
• B-class mobiles won’t get simultaneous support
from the network. Depending on MS design
• MS can try listen both paging channels
simultaneously by themselves
• MS does IMSI detach and use only GPRS service
• No effect on C-class mobiles as simultaneous
services are not supported
34. 3.5. Interworking with GSM services
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 34
(2/3)
Combined GPRS and IMSI attach
• To save radio resources
• MS indicates its request for combined attach
• MS sends combined GPRS and IMSI attach to SGSN
• SGSN may authenticate the MS
• SGSN informs MSC/VLR about the new MS
Combined Location and Routing Area update
• To save radio resources
• MS indicates its request for combined update
• This is done when both Location Area and Routing Area
changes at the same time
• Combined Location and Routing Area update is not done if
MS has CS connection
35. 3.5. Interworking with GSM services (3/3)
Paging CS services via GPRS network
•MSC/VLR gets MT call or SMS
• In VLR, presence of SGSN address tells that the MS is
in GPRS attached state
•MSC/VLR sends the paging request to SGSN address
(not to BSC)
• SGSN checks the location of MS (identified by IMSI)
• SGSN pages the MS via GPRS channels indicating “CS
page” status
•MS replies to the page using normal GSM channels
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 35
36. 4.1. SMS
4.2. Charging
4.3. O&M
4.4. Supplementary services
4.5. Quality of Service
4.6. Performance
NOKIA TELECOMMUNICATIONS
4. Special issues
IP TECH SCHOOL seminar / 23.11.1998 / slide 36
37. 4.1 Special issues: SMS support
MO and MT SMSs can be carried via GPRS network
HLR stores and returns two SS7 addresses to GMSC:
• SGSN address
• MSC/VLR address
Primary route:
• Via SGSN, if available
Secondary route:
• Via MSC/VLR, if available and primary failed
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 37
38. GPRS charging of PTP (1/2)
SGSN gathers charging:
• usage of radio resources (packets, bits)
• usage of packet data protocols (time)
• usage of general GPRS resources
• e.g. signaling messages, GPRS backbone
GGSN gathers charging :
• based on destination/source of data packets
• usage of external data networks (packets, bits)
• usage of general GPRS resources
Operator selects what information is used for billing
NOKIA TELECOMMUNICATIONS
4.2 Special issues:
IP TECH SCHOOL seminar / 23.11.1998 / slide 38
39. GPRS charging of PTM (2/2)
SGSN gathers usage of:
• usage of radio resources
• amount of data
• geographical areas
• number of repetition
• usage of general GPRS resources
PTM Service Center gathers charging :
• usage of general GPRS resource
• usage of PTM-G groups
NOKIA TELECOMMUNICATIONS
4.2 Special issues:
IP TECH SCHOOL seminar / 23.11.1998 / slide 39
40. Operation and management
GSM related parts can be handled with Q3
GPRS backbone network is based on IP network
• IP network uses Simple Network Management
Protocol (SNMP)
NOKIA TELECOMMUNICATIONS
4.3 Special issues:
IP TECH SCHOOL seminar / 23.11.1998 / slide 40
S G S N
IP
R O U T E R
G G S N
B T S B S C
G P R S
b a c k b o n e
n e t w o r k
( IP b a s e d )
P a c k e t
n e t w o r k
In t e r - o p e r a t o r
b a c k b o n e
n e t w o r k
D P a a t a
c k e t
n n e e t w t w o o r r k
k
( In t e r n e t )
G P R S / G S M O M C
O p e r a t o r A ' s G P R S
b a c k b o n e m a n a g e m e n t
In t e r - o p e r a t o r ' s G P R S
b a c k b o n e m a n a g e m e n t
D a t a n e t w o r k
m a n a g e m e n t
O p e r a t o r B ' s G P R S
b a c k b o n e m a n a g e m e n t
41. 4.4 Special issues:
Supplementary services
Most of the conventional GSM supplementary services
are not applicable for GPRS
• E.g., Call forwarding when busy, Calling line
identification, Call waiting
Some supplementary services may be applicable
• Advice of charge (can be difficult to realize)
• Closed user group (can be implemented as part of
external data network)
GPRS has its own supplementary services
• Barring of GPRS Interworking Profile(s)
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 41
42. • Precedence class (1,2,3)
• Delay class (1-4)
• Reliability class
• Peak throughput class; and
•Mean throughput class.
NOKIA TELECOMMUNICATIONS
4.5 Quality of Service
IP TECH SCHOOL seminar / 23.11.1998 / slide 42
43. • Data reliability is defined in terms of the residual error
rates for the following cases (see GSM 02.60):
• Probability of data loss
• Probability of data delivered out of sequence
• Probability of duplicate data delivery
• Probability of corrupted data
NOKIA TELECOMMUNICATIONS
4.5.1 Reliability Class
IP TECH SCHOOL seminar / 23.11.1998 / slide 43
44. 4.5.2 Throughput classes
Peak Throughput Class Peak Throughput in octets per second
Mean Throughput Class Mean Throughput in octets per hour
NOKIA TELECOMMUNICATIONS
1 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).
1 Best effort.
2 100 (~0.22 bit/s).
3 200 (~0.44 bit/s).
4 500 (~1.11 bit/s).
5 1 000 (~2.2 bit/s).
6 2 000 (~4.4 bit/s).
7 5 000 (~11.1 bit/s).
8 10 000 (~22 bit/s).
9 20 000 (~44 bit/s).
10 50 000 (~111 bit/s).
11 100 000 (~0.22 kbit/s).
12 200 000 (~0.44 kbit/s).
13 500 000 (~1.11 kbit/s).
14 1 000 000 (~2.2 kbit/s).
15 2 000 000 (~4.4 kbit/s).
16 5 000 000 (~11.1 kbit/s).
17 10 000 000 (~22 kbit/s).
18 20 000 000 (~44 kbit/s).
19 50 000 000 (~111 kbit/s).
IP TECH SCHOOL seminar / 23.11.1998 / slide 44
45. Example
• SGSN that handles 2 Mbps up and downlink traffic
– Average packet size 500 octets (4000 bits)
– => Each packet must be processed totally every 1 milliseconds
• IP stack in backbone
• possible UDP (de)fragmentation, IP checksums
• GTP header processing, finding the right context
• possible paging of the MS
• compression in SNDCP level, possible segmentation
• LLC CRC, LLC acknowledges, LLC timers
• handle GPRS ciphering/deciphering
• BSSGP protocol
• Frame relay protocol
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4.6 Performance 1/3
IP TECH SCHOOL seminar / 23.11.1998 / slide 45
46. Example continued
• Background tasks
– Ensuring the QoS for every mobile
– Handling charging data collection
– Performance monitoring
– Handle SGSN operating system, task switching, etc.
– Handle diagnostics of the network element
• If SGSN handles 65 Mbps, instead of 2 Mbps?
– => SGSN has just about 30 micro seconds to do all
above
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4.6 Performance 2/3
• Scheduling pending packets to time horizon
• Rescheduling everything after MS has changed the cell
IP TECH SCHOOL seminar / 23.11.1998 / slide 46
47. Solution to the example
• Each network element has limited capacity (x
packets/second)
• If operator needs more capacity (e.g. 50x)
– use 50 parallel boxes
– for example,
• every GGSN boxes are really independent of each other
• each SGSN handles its own area (list of cells)
• Capacity grows linearly but complexity in each box
remains the same
• Reliability? Configuration?
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4.6 Performance 3/3
IP TECH SCHOOL seminar / 23.11.1998 / slide 47
48. 5. GPRS Business View
5.1. What must be invested to get GPRS up and running?
5.2. How to launch GPRS with minimised incremental cost
5.3. How to make money with GPRS?
5.4. Users' benefits of GPRS
5.5. Business model
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 48
49. 5.1 What must be invested to get GPRS
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 49
up and running?
• Updates on existing network elements
– BTS, BSC, MSC/HLR, O&M, billing system, network
planning
• New network elements
– Totally new network for GPRS backbone, based on IP
– New packet network nodes
– A lot of Internet "stuff" (routers, DNS servers, firewalls, …)
• Totally new skills needed
– "Internet way" of thinking
• New mobiles and new type of users
• New type of business thinking
50. 5.2 How to launch GPRS with minimised
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 50
incremental cost
• A single SGSN/GGSN combined functional unit
• BTSs support basic GPRS services with software
update only, BSCs need HW upgrade to add connection
to SGSN
• Use existing paging and control channels for GPRS
• Limit the number of radio channels available for GPRS
• Gs interface can be deleted => no MSC developments
51. 5.3. How to make money with
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 51
GPRS?
• New users
– More subsribers
• New services
– New ways to get money from users
– New intances to pay instead of the users (e.g. advertisers)
• New applications
– New ways to get money from users
•More data traffic
– More data traffic
– Small payments per packet, but huge number of packets
52. 5.4. Users' benefits of GPRS
• GPRS Selling arguments:
– Higher capacity Internet access
– Quicker access to Internet
– Lower cost
– Or no cost
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• Up to 171,2 kbps in theory, 40 kbps in practice
• No set up time, Iternet access all the time available
• Flat rate or volume based billing
• via anonymous access (somebody else pays the bill)
IP TECH SCHOOL seminar / 23.11.1998 / slide 52
53. Example business model
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5.5. Business model
IP TECH SCHOOL seminar / 23.11.1998 / slide 53
1/2
• If the users are paying little (or nothing), how does this
make profit to the operator?
– Not the high cost per time but the large number of packets
– Somebody else may pay the bill (e.g. anonymous access)
# sub- QoS level Monthly Cost/kB Volume/ Monthly Total annual Total data
scribers fee (FIM) FIM day (FIM) cost/subs cost (MFIM) volume (GB)
Business users 100000 High 50 0,02 1000 650 780 36500
"Normal" users 1000000 Normal 25 0,01 20 31 372 7300
Web surfers 1000000 Best effort 50 0 250 50 600 91250
Computers 100000 High 50 0,1 20 110 132 730
Total 2200000 1884 135780
54. 5.5. Business model 2/2
Volume calculations
Average data per day 372 GB/d
volume per hour 15,5 GB/h
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 54
per sec 4,3 MB/s
per sec 34,3 Mbps
Peak hour data per year 43800 GB/a
volume per day 120 GB/d
per hour 30 GB/h all data in 4 busy hours
per sec 8,3 MB/s
per sec 66,7 Mbps
Number of time 6667 TSs average 10 kbps/TS
slots needed
Carrier 833 Carriers
55. 6. GPRS Standardization
GPRS Phase 1: Release 97
• Basic set of GPRS functionality
• Optional features
GPRS Phase 2: GPRS for UMTS
• Certain issues defined in stage 1 documents are not
included in the first release of the GPRS standard
• New requirements have been pointed out for UMTS
Standard was approved March/June 1998
NOKIA TELECOMMUNICATIONS
IP TECH SCHOOL seminar / 23.11.1998 / slide 55
56. The following companies and organizations have been
participating in GPRS work in last 3 years
Some of the manufacturers, operators and others
participating GPRS standardization:
• Alcatel, BT, CNET, CSELT, Detemobil, Eplus,
Ericsson, France Telecom, IBM, Inmarsat, Lucent,
Mannesmann, Motorola, NEC, Nokia, Nortel/Matra,
Omnipoint, OPI, Philips, SFR, Siemens, Telecom
Finland, Telia, UIC, Vodafone
EU sponsored project team PT8OV to expedite GPRS
standardization
Support of PT12
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6.1 List of participants
IP TECH SCHOOL seminar / 23.11.1998 / slide 56
57. 6.2 GPRS Specifications
GPRS document structure
Doc. Title
01.60 Requirements Specification of GPRS
Stage 1
02.60 General GPRS Overview
10.60 GPRS standarsisation status and overview
Stage 2
03.60 General System Description and Newtwork Architecture
03.64 Radio Architecture Description
03.61 Point to Multipoint – Multicast (very draft)
03.62 Point to Multipoint – Group Call (non existing)
New Stage 3
04.60 Radio stage 3: RLC/MAC Radio Protocol
04.61 PTM-M Services (not existing yet)
04.62 PTM-G Services (not existing yet)
04.64 LLC
04.65 SNDCP
07.60 User Interworking
08.18 BSSGP: The Gb Interface
08.16 Gb Network Service
08.14 Gb Layer 1
09.16 Gs Layer 2
09.18 Gs Layer 3
09.60 GPRS Tunnelling Protocol (GTP): Gn & Gp Interface
09.61 External Interworking Networks
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IP TECH SCHOOL seminar / 23.11.1998 / slide 57