IP TECH SCHOOL seminar / 23.11.1998 / slide 1
NOKIA TELECOMMUNICATIONS
General Packet Radio Service(GPRS)
Petteri Lappalainen
23.11.1998
IP Tech School
Seminar PresentationBased on the material by
Tuomas Niemelä (-97), Hannu H. Kari (-98) and ETSI
IP TECH SCHOOL seminar / 23.11.1998 / slide 2
NOKIA TELECOMMUNICATIONS
Wireless roadmap
IP TECH SCHOOL seminar / 23.11.1998 / slide 3
NOKIA TELECOMMUNICATIONS
Contents1. 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 4
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 5
NOKIA TELECOMMUNICATIONS
1.1. What is GPRS ?
• 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 6
NOKIA TELECOMMUNICATIONS
1.2. GPRS access interfaces and reference points
Gi reference point
GPRS network 1
GPRS network 2
PDNs orother networksTE MT
Gp
UmR reference point
MS
• GPRS provides packet switched connections from MS to packet data networks (PDN)
• Different operator’s GPRS networks are connected through Gp interface
IP TECH SCHOOL seminar / 23.11.1998 / slide 7
NOKIA TELECOMMUNICATIONS
1.3. How is GPRS seen by external networks and GPRS users?
L ocal areanetwork
R outerC orpor ate 2
L ocal areanetwork
R outer
C orporate 1P ac ketnetw o rkDatanetwork(Internet)
G P R S S UB NE TW O R K
S UB NE TW O 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
HO S T191.200.44.21
HO S T131.44.15.3
HO S T155.222.33.55
"R outer"
IP TECH SCHOOL seminar / 23.11.1998 / slide 8
NOKIA TELECOMMUNICATIONS
1.4. Air interface resources
0
2
4
6
8
10
12
14
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
2
4
6
8
10
12
14
3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00
TCH
Capacity occupied by CS traffic
FreeCapacityGPRS "steals" any TCH
capacity not used by CStraffic
IP TECH SCHOOL seminar / 23.11.1998 / slide 9
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 10
NOKIA TELECOMMUNICATIONS
1.6. Applications
• Standard data network protocol based• IP based applications
– WWW, FTP, Telnet, ...
– Any conventional TCP/IP based applications
• X.25 based applications
– Packet Assembly/Disassembly (PAD) type approach
• GPRS specific protocol based• Point-to-point applications
– Toll road system, UIC train control system
• Point-to-multipoint applications
– Weather info, road traffic info, news, fleet management
• SMS delivery (GPRS as a bearer for SMS)
IP TECH SCHOOL seminar / 23.11.1998 / slide 11
NOKIA TELECOMMUNICATIONS
2. GPRS architecture
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 12
NOKIA TELECOMMUNICATIONS
2.1. Interfaces, reference points and network elements
MAP-F
Gi
Gn
Gb
GcMAP-D
MAP-CMAP-H
Gp
Gs
Signalling and Data Transfer Interface
Signalling Interface
MSC/VLR
TE MT BSS TEPDN
R Um
GrA
HLR
Other PLMN
SGSN
GGSN
Gd
SM-SCSMS-GMSC
SMS-IWMSC
GGSN
EIR
IP TECH SCHOOL seminar / 23.11.1998 / slide 13
NOKIA TELECOMMUNICATIONS
2.2. Functional view on 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 14
NOKIA TELECOMMUNICATIONS
Function MS BSS SGSN GGSN HLR
Network Access Control:Registration XAuthentication and Authorisation X X XAdmission Control X X XMessage Screening XPacket Terminal Adaptation XCharging Data Collection X X
Packet Routeing & Transfer:Relay X X X XRouteing X X X XAddress Translation and Mapping X X XEncapsulation X X XTunnelling X XCompression X XCiphering X X X
Mobility Management: X X X X
Logical Link Management:Logical Link Establishment X XLogical Link Maintenance X XLogical Link Release X X
Radio Resource Management:Um Management X XCell Selection X XUm-Tranx X XPath Management X X
Assignment of functions to general logical architecture
IP TECH SCHOOL seminar / 23.11.1998 / slide 15
NOKIA TELECOMMUNICATIONS
2.3. Subscription of GPRS 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)
IP TECH SCHOOL seminar / 23.11.1998 / slide 16
NOKIA TELECOMMUNICATIONS
2.3. Subscription of GPRS 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 17
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 18
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 19
NOKIA TELECOMMUNICATIONS
2.4.3. Other elementsBG (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
IP TECH SCHOOL seminar / 23.11.1998 / slide 20
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 21
NOKIA TELECOMMUNICATIONS
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)
IP TECH SCHOOL seminar / 23.11.1998 / slide 22
NOKIA TELECOMMUNICATIONS
2.6. GPRS multislot capabilities
0MS RX
MS TX
Monitor
1 2 3 4 5 6 7 0 1
0 2 3 4 5 65 6 7 1
MS RX
MS TX
Monitor
0 1 2 3 4 5 6 7 0 1
0 2 3 4 5 65 6 7 1
MS RX
MS TX
Monitor
0 1 2 3 4 5 6 7 0 1
0 2 3 4 5 65 6 7 1
3 slots: 4th slot: 5th slot:
1-slot
2-slot
3-8 -slot
IP TECH SCHOOL seminar / 23.11.1998 / slide 23
NOKIA TELECOMMUNICATIONS
3. GPRS operations
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 24
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 25
NOKIA TELECOMMUNICATIONS
3.2. GPRS Attach
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 26
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 27
NOKIA TELECOMMUNICATIONS
3.3. Data transfer (2/4)
Mobile originated (left when MS in HPLMN, right when in VPLMN, no filtering/screening)
Local areanetwork
Server
Router
SGSN
GGSN
BG
BSCBTS
Intra-PLMNbackbonenetwork(IP based)
SGSN
GGSN
BG
BSC BTS
Intra-PLMNbackbonenetwork(IP based)
Packetnetwork
Inter-PLMNbackbonenetwork
Packetnetwork
Datanetwork(Internet)
Corporate
HPLMN VPLMN
IP TECH SCHOOL seminar / 23.11.1998 / slide 28
NOKIA TELECOMMUNICATIONS
3.3. Data transfer (3/4)
Mobile terminated (left when MS in HPLMN, right when in VPLMN, with/without filtering/screening)
Local areanetwork
Server
Router
SGSN
GGSN
BG
BSCBTS
Intra-PLMNbackbonenetwork(IP based)
SGSN
GGSN
BG
BSC BTS
Intra-PLMNbackbonenetwork(IP based)
Packetnetwork
Inter-PLMNbackbonenetwork
Packetnetwork
Datanetwork(Internet)
Corporate
HPLMN VPLMN
IP TECH SCHOOL seminar / 23.11.1998 / slide 29
NOKIA TELECOMMUNICATIONS
3.3. Data transfer (4/4)
Mobile originated and terminated (left MSs in same PLMN, right MSs in different PLMN)
Local areanetwork
Server
Router
SGSN
GGSN
BG
BSCBTS
Intra-PLMNbackbonenetwork(IP based)
SGSN
GGSN
BG
BSC BTS
Intra-PLMNbackbonenetwork(IP based)
Packetnetwork
Inter-PLMNbackbonenetwork
Packetnetwork
Datanetwork(Internet)
Corporate
HPLMN VPLMN
BSCBTS
SGSN
IP TECH SCHOOL seminar / 23.11.1998 / slide 30
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 31
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 32
NOKIA TELECOMMUNICATIONS
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)
– Intra-SGSN Routing Area Update
– Inter-SGSN Routing Area Update
• Periodic Routing Area updates are applicable
IP TECH SCHOOL seminar / 23.11.1998 / slide 33
NOKIA TELECOMMUNICATIONS
3.5. Interworking with GSM services (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
IP TECH SCHOOL seminar / 23.11.1998 / slide 34
NOKIA TELECOMMUNICATIONS
3.5. Interworking with GSM services (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
IP TECH SCHOOL seminar / 23.11.1998 / slide 35
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 36
NOKIA TELECOMMUNICATIONS
4. Special issues
4.1. SMS
4.2. Charging
4.3. O&M
4.4. Supplementary services
4.5. Quality of Service
4.6. Performance
IP TECH SCHOOL seminar / 23.11.1998 / slide 37
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 38
NOKIA TELECOMMUNICATIONS
4.2 Special issues: 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 39
NOKIA TELECOMMUNICATIONS
4.2 Special issues: 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 40
NOKIA TELECOMMUNICATIONS
4.3 Special issues: 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)
S G S N
G G S N
IP R O UTE R
B S CB TS
G P R Sbackbonenetwork(IP based)
P ac ketnetwork
Inter-operatorbackbonenetwork
P acketnetwork
Datanetwork(Internet)
G P R S /G S M O MC
O perator A's G P R S bac kbone management
Inter-operator's G P R S bac kbone management
Data network management
O perator B 's G P R S bac kbone management
IP TECH SCHOOL seminar / 23.11.1998 / slide 41
NOKIA TELECOMMUNICATIONS
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)
IP TECH SCHOOL seminar / 23.11.1998 / slide 42
NOKIA TELECOMMUNICATIONS
4.5 Quality of Service
• Precedence class (1,2,3)
• Delay class (1-4)
• Reliability class
• Peak throughput class; and
• Mean throughput class.
IP TECH SCHOOL seminar / 23.11.1998 / slide 43
NOKIA TELECOMMUNICATIONS
4.5.1 Reliability Class
• 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 44
NOKIA TELECOMMUNICATIONS
4.5.2 Throughput classesPeak Throughput Class Peak Throughput in octets per second
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).
Mean Throughput Class Mean Throughput in octets per hour
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 45
NOKIA TELECOMMUNICATIONS
4.6 Performance 1/3
• 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
Example
IP TECH SCHOOL seminar / 23.11.1998 / slide 46
NOKIA TELECOMMUNICATIONS
4.6 Performance 2/3
• Background tasks– Ensuring the QoS for every mobile
• Scheduling pending packets to time horizon
• Rescheduling everything after MS has changed the cell
– 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
Example continued
IP TECH SCHOOL seminar / 23.11.1998 / slide 47
NOKIA TELECOMMUNICATIONS
4.6 Performance 3/3
• 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?
Solution to the example
IP TECH SCHOOL seminar / 23.11.1998 / slide 48
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 49
NOKIA TELECOMMUNICATIONS
5.1 What must be invested to get GPRS 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 50
NOKIA TELECOMMUNICATIONS
5.2 How to launch GPRS with minimised 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 51
NOKIA TELECOMMUNICATIONS
5.3. How to make money with 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
IP TECH SCHOOL seminar / 23.11.1998 / slide 52
NOKIA TELECOMMUNICATIONS
5.4. Users' benefits of GPRS
• GPRS Selling arguments:– Higher capacity Internet access
• Up to 171,2 kbps in theory, 40 kbps in practice
– Quicker access to Internet• No set up time, Iternet access all the time available
– Lower cost• Flat rate or volume based billing
– Or no cost• via anonymous access (somebody else pays the bill)
IP TECH SCHOOL seminar / 23.11.1998 / slide 53
NOKIA TELECOMMUNICATIONS
5.5. Business model1/2
• 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 datascribers 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 7300Web surfers 1000000 Best effort 50 0 250 50 600 91250Computers 100000 High 50 0,1 20 110 132 730Total 2200000 1884 135780
Example business model
IP TECH SCHOOL seminar / 23.11.1998 / slide 54
NOKIA TELECOMMUNICATIONS
5.5. Business model 2/2
Average data per day 372 GB/dvolume per hour 15,5 GB/h
per sec 4,3 MB/sper sec 34,3 Mbps
Peak hour data per year 43800 GB/avolume per day 120 GB/d
per hour 30 GB/h all data in 4 busy hoursper sec 8,3 MB/sper sec 66,7 Mbps
Number of time 6667 TSs average 10 kbps/TSslots needed
Carrier 833 Carriers
Volume calculations
IP TECH SCHOOL seminar / 23.11.1998 / slide 55
NOKIA TELECOMMUNICATIONS
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 56
NOKIA TELECOMMUNICATIONS
6.1 List of participants
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
IP TECH SCHOOL seminar / 23.11.1998 / slide 57
NOKIA TELECOMMUNICATIONS
6.2 GPRS SpecificationsGPRS document structure
Doc. Title
01.60 Requirements Specification of GPRS
Stage 102.60 General GPRS Overview10.60 GPRS standarsisation status and overview
Stage 203.60 General System Description and Newtwork Architecture03.64 Radio Architecture Description03.61 Point to Multipoint – Multicast (very draft)03.62 Point to Multipoint – Group Call (non existing)
New Stage 304.60 Radio stage 3: RLC/MAC Radio Protocol04.61 PTM-M Services (not existing yet)04.62 PTM-G Services (not existing yet)04.64 LLC04.65 SNDCP07.60 User Interworking08.18 BSSGP: The Gb Interface08.16 Gb Network Service08.14 Gb Layer 109.16 Gs Layer 209.18 Gs Layer 309.60 GPRS Tunnelling Protocol (GTP): Gn & Gp Interface09.61 External Interworking Networks