Transcript GPRS - MobiHealth

GPRS
(General Packet Radio Service)
Telefónica Móviles España
GPRS Characteristics
• GPRS is a new technology that optimises the use of
network and radio resources:
– Users share radio resources.
– Only used when data are sent or received.
– Uses a packet-mode technique to transfer data and
signalling in an efficient manner.
• GPRS data transfer is based on the Internet Protocol
(IP). The packet data transmission is carried out on an
end-to-end basis, including the air interface.
• GPRS operates on the same radio frequencies as the
circuit-switched GSM system. Co-existence of GSM and
GPRS networks.
2
Introducción
GPRS Characteristics
• Billing based on data volume, NOT on time.
• Data transfer rate depends on the load: number of users
(GPRS and non GPRS).
• GSM-GPRS network turns into a “Wireless LAN” with IP
mobile devieces connected.
• Always-ON.
• Assignment divided into uplinks and downlinks.
3
What IS and IS NOT GPRS?
What is?
 Data transmission
technology in mobility
 A substitute for WAP
 A substitute for GSM
 A complement for GSM
 An alternative to UMTS
 Technological support for
new services
 A new service
 New business model
generator
 2.5 G: a step forward 3G
4
What is NOT?
 Multimedia services
 ADSL for mobile
phones
GPRS rates
Radio Carrier: 8 channels
12345678
GSM Voice: 1 conversation  1 channel
1 channel for GSM data
 9.6 kbps
GPRS: Use of until 8 channels per user
Depending on the code algorithm, we can get several
transmission rates:
CS-1: 9.05 kbps/slot
CS-3: 15.6
kbps/slot
CS-2: 13.4 kbps/slot
CS-4: 21.4
kbps/slot
Actually terminals support until 4+1 slots
5
Efficiency in resources use: until 8 users/channel.
GPRS Applications
• Burst Applications with high bandwidth:
– E-mail, WWW, FTP
• Applications with low bandwidth:
– Telemetry, Remote control, e-commerce.
• Multicast Services:
– Metereological, Traffic or Corporate Information.
6
GPRS Architecture
BTS
MSC/VLR
BSC
EIR
HLR
SGS
N
External
IP Network
MS
Backbone
Network
Traffic and signalling
Signalling
7
AUC
GGS
N
External
X.25 Network
GPRS Architecture
• GPRS is implemented on the GSM structure through
the addition of two new network nodes:
– SGSN (Serving GPRS Support Node) provides packet
routing to and from the geographical SGSN area.
– GGSN (Gateway GPRS Support Node) provides
interworking with external packet-switched networks.
• BSC needs a SW and HW upgrade, the PCU (Packet
Control Unit).
8
SGSN Main Tasks
• Packet routing towards the adequate GGSN.
• Security over radio access: ciphering and
authentication.
• Mobility management: keeps track of the MS (Mobile
Station) location.
• Logical link management towards the MS.
• Connection to GSM nodes: MSC, HLR, BSC, SMS-C.
• Charging data.
9
GGSN Main Tasks
• Interface with the external IP packet networks.
• Security functions toward the Internet (Radius client).
• GPRS session management on IP level;
communication setup towards external network.
• Associating subscribers with the appropriate SGSN.
• Charging data.
10
PCU Main Tasks
• Multiplexing of GPRS traffic and circuit switched
traffic.
• Handling of GPRS radio resources: allocating
channels for GPRS connections.
• Distribution of packet data to the MS.
• Handling connections towards the SGSN.
11
BTS & HLR
• BTS (Base Transceiver Station): Responsible for
separating the MS originating circuit-switched (CS) calls
from packet data communication before the BSC
forwards:
– CS calls to the MSC/VLR
– PS data to the SGSN
• HLR (Home Location Register): The subscriber file
must contain GPRS subscription data:
– Address of the SGSN currently serving the subscriber
– Addresses of GGSNs that will be contacted when activity from
MS is detected
– Access Point Name (APN) describing the access point to the
external computer network
12
GPRS security
• SGSN performs authentication and cipher setting
procedures based on the same algorithms, keys, and
criteria as in existing GSM.
• SGSN and GGSN use GTP (GPRS Tunnelling
Protocol) in order to encapsule the packets. GTP is
assembled over TCP/IP.
• Tunnelling: The information will be ciphered and
additional data will be included to every packet to
guarantee confidentiality.
13
GPRS MoviStar Services
• e-moción GPRS: Mobile Internet Access Service. It
uses WAP protocol over GPRS to access to different
contents in e-moción.
• MoviStar Internet: Allows to surf to everywhere and
everytime with only a laptop or PDA and a MoviStar
GPRS mobile telephone. The customer has direct,
generic and anonymous access to Internet without the
need of an ISP.
• MoviStar Intranet: Allows direct access to LAN
networks and corporate applications (Intranet, e-mail,
databases, corporate directory, agenda) everywhere
and everytime with only a laptop or PDA and a MoviStar
GPRS mobile telephone.
14