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© Sunrise 18.04.23
GSM Data evolution
EDGE
GSM HSCSD services upto 38.4 kbit/s (later up to 64 kbit/s)
PDS services low bit rates
GSM GPRS services upto 160 kbit/s
UMTS
GSM CS data services upto 9.6 kbit/s
91/92 98 99/00 02
Functionality
© Sunrise 18.04.23
GPRS evolution towards 3rd Generation
HSCSD “High Speed Circuit Switched Data”1st step in GSM Phase 2+ that clearly increase achievable data Rates in the GSM System 14.4kbps Channel Coding =115.2kbps for 8 Tsl Maximum data rate is limited to 64kbps due to CN a A-Interface limitationPrecondition:Modify GSM Network to support HSCSD in BSC & MSCHandsets has to support Multislot Capabilities Today HSCSD (Data Cards)Handsets support 4 Tsl in Downlink and up to 2 Tsl in Uplink Direction
© Sunrise 18.04.23
GPRS evolution towards 3rd Generation
Depending on the Cell Configuration amount of Users is restricted Multiple User cannot share a Tsl at the Air InterfaceDepending on the Bearer Nature “Circuit Switched” a Tsl is dedicated to a SubscriberAmount of Subscriber per Tsl is limited to 1Circuit Switched Data has a long access time Call Charging is based on connection time
© Sunrise 18.04.23
GPRS evolution towards 3rd Generation
GPRS “General packet Radio System”
Connections do not reserve resources permanently, which is Highly efficient for applications with a bursty natureShort access time to the NetworkCharging model can be based on transmitted volume GPRS brings packet switched bearer services to the existing GSM SystemUser can Access Public Data Network directly using their Standard protocol addresses (IP, X.25)GPRS Mobile can use between 1-8 channels over the air interface depending on the MS capabilities
© Sunrise 18.04.23
GPRS evolution towards 3rd Generation
Resource allocation is dynamic and dependent on demand and Resource Availability Packets can be sent on idle time between speech call depending MS class typesPossible traffic types point to point point to multipoint (postponed to Release 4&5) SMS capability Anonymous access (planned)Maximum Theoretical throughput per MS using 8 Tsl without Error Correction is 160kbps
© Sunrise 18.04.23
GPRS Logical Architecture
Gf
Gi
Gn
Gb
GcD
CE
Gp
Gs
Signaling and Data Transfer Interface
Signaling Interface
MSC/VLR
TE MT BSS TEPDN
R Um
GrA
HLR
Other PLMN
SGSN
GGSN
Gd
SM-SCSMS-GMSC
SMS-IWMSC
GGSN
EIR
© Sunrise 18.04.23
GPRS Logical Architecture
BSC
GMSCMSC/VLR
SGSN
PTM-SC
EIR
HLR
AUC
GGSNIP-Backbone Network
ExternalIP Network
External X.25 Network
Gs
Gf
Gr
Traffic & Signaling
Signaling
BTS - Base Transceiver StationBSC - Base Station ControllerMSC - Mobile Switching CentreHLR - Home Location RegisterSGSN - Serving GPRS Support NodeGGSN - Gateway GPRS Support NodePTM-SC - Point-to-Multipoint Service Centre
Notebook & GPRS mobile
BTS
Gb
ExternalIP Network
Um
ISDN/PSTN
Gn
Gi
© Sunrise 18.04.23
GPRS Network Node Functionality
• SGSN and GGSN are IP based packet switching nodes
• SGSN supports basic mobility management, session management, subscription checking, charging
• GGSN supports session management, charging and provides interconnect points to ISPs (Internet Service Provider)
• BSC (PCU) supports the Radio Link- and MediumAccess Control protocol (RLC/MAC)
• BTS supports new channel coding and interleaving
• HLR supports subscriber data management
© Sunrise 18.04.23
GPRS Mobiles
• Class A: Simultaneous usage of Circuit- and Packet switched services (2 TRX=Dual Transfer Mode DTM is precondition).
• Class B: Automatic choice of service, Circuit- or Packet switched, but only one at a time (1 TRX). Suspension/resumption of GPRS services at setup/release of CS connection.
• Class C: Manually selected use of either Circuit- or Packet switched service. Special case is a packet only MS (1TRX).
• Class A: Simultaneous usage of Circuit- and Packet switched services (2 TRX=Dual Transfer Mode DTM is precondition).
• Class B: Automatic choice of service, Circuit- or Packet switched, but only one at a time (1 TRX). Suspension/resumption of GPRS services at setup/release of CS connection.
• Class C: Manually selected use of either Circuit- or Packet switched service. Special case is a packet only MS (1TRX).
© Sunrise 18.04.23
GPRS Mobile Station “Multislot Classes”
Class Download Upload Max.slots1 1 1 2
2 2 1 33 2 2 34 3 1 45 2 2 46 3 2 47 3 3 58 4 1 59 3 2 510 4 2 511 4 3 512 4 4 513 3 3 unlimited14 4 4 unlimited15 5 5 unlimited16 6 6 unlimited17 7 7 unlimited18 8 8 unlimited19 6 2 unlimited20 6 3 unlimited21 6 4 unlimited22 6 4 unlimited23 6 6 unlimited24 8 2 unlimited25 8 3 unlimited26 8 4 unlimited27 8 4 unlimited28 8 6 unlimited29 8 8 unlimited
© Sunrise 18.04.23
GPRS Transmission Plan
GSM RF
MAC
RLC
LLC
SNDCP
IP / X.25 IP / X.25
GTP
L1
L2
Application
GSM RF
FrameRelay
MAC
RLC BSSGP
L1bis
BSSGPFrameRelay
LLC
SNDCP GTP
L1bis L1
L2
IP
MS BSS (PCU) SGSN GGSNUm GnGb Gi
IP
UDP/TCP
UDP/TCP
© Sunrise 18.04.23
GPRS Handset IP Address Assignment
Mobile User connects to specified APNAPN is configured in the GGSNKinds of Handset IP address assignment
GGSN pool per APN Subscriber IP Address assignmentexternal DHCP ServerIntranet DHCP ServerFixed IP Address Assignment in the HLR per Subscriber and APN (not or!!)
© Sunrise 18.04.23
GPRS Routing and Address Plan
IPv4 ‣used In GPRS Backbone (public & private)
‣used for Handsets (public & private)
IPv6 ‣Backbone can support with Release 99
implementation
‣current used GPRS capable Handsets
does not support IPv6
‣1st steps visible for UMTS Handsets only
© Sunrise 18.04.23
GPRS Routing and Address Plan
Further necessary Routing Instrument for GPRS
TLLI=Temporary Logical Link ID
Routing AreaLocation Area
© Sunrise 18.04.23
GPRS Routing and Address Plan
BVCI /LA/RA
Handset IP
GTP Address
Tunnel ID =IMSI
Handset IP
TLLI
Gb Interface Gn InterfaceSGSN<->BSC SGSN<->GGSN
© Sunrise 18.04.23
Avoid Collision at the Air Interface
Data Transmission divided in to Up- and Downlink Data Traffic
USF0 USF1 USF2 USF3 USF4 USF5 USF06USF7Free
Uplink
TFI0 TFI1 TFI2 TFI3 TFI4 TFI5 TFI6 TFI7 TFI8
Uplink
Downlink
© Sunrise 18.04.23
GPRS Multiplexing at RLC/MAC Layer
SDCCH&SACCH CS CS CSCS CS PSBCCH
CCCH
USF0
USF1
USF2
USF3
USF4
USF5
USF6
USF7
TFI0
TFI1
TFI2
TFI3
TFI4
TFI5
TFI6
TFI7TFI8
Uplink
© Sunrise 18.04.23
GPRS Coding Schemes based on RLC/MAC
Coding Rate Info (bits)
CRC (bits)
Abis unchanged
Data rate (kbps)
R=1/2 (SDCCH)
184 40 yes 9.05
R=2/3 272 16 yes 13.4
R=3/4 320 16 no 15.6
R=1 440 16 no 21.4
Coding Rate Info (bits)
CRC (bits)
Abis unchanged
Data rate (kbps)
R=1/2 (SDCCH)
184 40 yes 9.05
R=2/3 272 16 yes 13.4
R=3/4 320 16 no 15.6
R=1 440 16 no 21.4
© Sunrise 18.04.23
GPRS Quality of Service Profile
1) Delay for packets of 128 octets; • Delay class 1 (mean 0.5 sec, 95% < 1.5 sec)
• Delay class 2 (mean 5 sec, 95% < 25 sec)
• Delay class 3 (mean 50 sec, 95% < 250 sec)
• Delay class 4 (unpredicted)
2) Reliability
• Reliable data transfer (retransmission, delay)
• Unreliable data transfer (no retrans., small delay)
• Unreliable data transfer, erroneous data discarded (no retrans., small delay, data loss)
© Sunrise 18.04.23
GPRS Quality of Service Profile
3) Priority
Priority class 1 (highest priority)
• Priority class 2• Priority class 3• Priority class 4 (lowest priority)•
4) Mean and 5) Peak throughput
© Sunrise 18.04.23
GPRS Roaming using IPSEC Tunnel via Internet
Operator A Operator B
Internet IPsec Tunnel via the Internet
© Sunrise 18.04.23
GPRS Roaming using GRX
BTS MS
Operator A. GPRS Backbone as HOME OPERATOR
SGSN
GGSN
BSC
Border GW
BTS
MS
Operator B. GPRS Backbone as VISITED OPERATOR
SGSN GGSN
BSC
Border GW
Inter PLMN Backbone Service network
Public Internet
DNS DNS
Charcing GW Charging GW
Public Internet
Public Internet Public Internet
Root DNS Info Base