Transcript Introduction to GPRS

2.5 G Cellular Systems and Architecture
1
2.5G Cellular System
• Introduction to GPRS and EDGE
• 2.5G System Architecture
2
Evolution of Wireless
3
GPRS
• General Packet Radio Service
• Value added service to 2G to connect users
to IP (Internet Protocol) -based data
networks
• Forms basis of Packet Switched Network
• Data rate up to 115 Kbps with GPRS and
384 Kbps with EDGE
4
Motivation for GPRS
• Wireless access to internet and intranet
5
Circuit and Packet Switching
• Circuit Switching
o Dedicated resources to each user
o Higher performance and higher cost
• Packet Switching
o Shares resources with multiple users
o Lower performance and lower cost
o Requires MAC (Medium Access Control)
o Requires memory buffering
6
Circuit Switching Network
7
Packet Switching Network
8
EDGE
• Enhanced Data rate for Global Evolution
• Also called as Enhanced GPRS or EGPRS
• Improves efficiency of GPRS by use of
advanced modulation technique- Octal PSK
or 8 PSK Modulation
9
GPRS Network
10
GPRS Network Terms
11
Major functions of SGSN
• Provides Packet Switching and routing for
GPRS services- analogous to MSC in 2G
• Contains a database of subscribers,
including visitors (roamers) and home
subscribers- analogous to VLR in 2G
• Handles authentication and admission
control – analogous to MSC/HLR/AuC
12
Major functions of GGSN
• Provides Packet Switching and Routing for
GPRS services
• Provides interface to external Public Data
Networks (PDNs) e.g. the Internet
• First point of contact for packet session
originating outside the PLMN
13
Major functions of GERAN
• Handles admission control
• Handles radio resource management
• Performs packet relay and routing functions
14
Elements of Communication System
Source
Transmitter
Transmission
Channel
Receiver
Destination/
Transdcers
Noise,
interference
and distortion
15
Typical Wireless Terminal
User
Interface
Digital
Baseband
Analog-Digital
Interface
(Analog
Baseband)
RF Front-end
16
Typical 2.5G Wireless Terminal
VCXO_ON
I2C
Vcc TX
Vcc Synth
Tx Data
13MHz
VCTCXO
Vcc
VCTCXO
Control
Vcc TX
Vcc Synth
Vcc
VCTCXO
Vcc RX
Vcc ABB
Vcc
Manitoba
Rx Data
RX
GPRS
mixed
Voiceband
Port
signal
solution
SPI
Synthesizer
GSM/GPRS
RF solution
Vcc TX
MAIN
VCO
13MHz
RF Filter
Control
SPI
Control
SPI
Control
RFCLK
(13MHz)
T/R Switch
GSM/
GPRS
Digital
Baseband
Vcc Synth
Aux.
Port
Vcc RX
AFE
Vcc
ABB
Audio I/F
Aux Pins
JTAG
Baseband
Port
PMIC
Control
TX
Control
TX VCO
LPF
Vcc TX
Band
Vcc TX
PA
Vcc
Manitoba
PA Control
Ramp Control
Control
Ramp
17