Transcript - Pcpolytechnic

Supporting Nodes
•SGSN(serving GPRS supporting Node)
Functions1]Packet switching
2]Routing and transfer
3]Mobility Management
4]Logical Link management
5]Authentication
6]Charging
Supporting Nodes
•GGSN(Gateway GPRS support Node)
Function
1]It acts as an interface between GPRS backbone
network and external packet data network
2]It maintain routing information that is
necessary to route (PDU) of SGSN mobile user
3]Translation
It stores the current SGSN address of the user
and his profile in its location register.
4]Authentication and charging function
GPRS Network Enhancements
•BssBTS upgrade to allow transportation of user data
to the SGSN also the BTS needs to upgrade to
support packet data transportation between the
BTS and the Ms over the air interface
•Home Location Information
HLR needs enhancement to register GPRS user
profiles and respond to queries originating from
GSNs
•MS
•Network Layer
•(IP or X.25)
•Relay
•SNDCP
GTP
•GTP
•
•LLC
•TCP/UDP
•
•Relay
•RLC
TCP/UDP
BSSP
•BSSGP
IP
•IP
•MAC
•
Network
Service
•Network
•Service
Data Link
Service
•Data Link
•Layer
•PLL
•RFL
Phy Layer
•Phy Layer
Phy Layer
•Phy layer
•Gm
•BSS
•RLC :Radio link control
•PLL :Physical link layer
•RFL :Physical RF layer
•MAC:Medium access control
•
•Gb •GGSN
•SGSN
BSSGP:BSS GPRS Application protocol
GTP :GPRS tunneling protocol
TCP :Transmission control protocol
UDP :user datagram protocol
IP
:Internet Protocol
•Transmission Plane
•Gi
• MS
•BSS
•Application
•Network Layer
•SNDCP
•LLC
•RLC
•MAC
•PLL
•RFL
•Relay
•RLC
•MAC
•
•PLL
•
•RFL
• Um
•SNDCP:Subnetwork dependent• convergence protocol
•LLC :Logical link control
•RLC :Radio link control
BSSGP
Network
Service
PHY
Layer
Signaling plane
•The protocol architecture of the signaling plane
consist protocol used to control and support the
function of transmission plane
•It includes signaling information about
1]GPRS attach and detach
2]PDP context activation
3]Control of routing paths
4]Allocation of new resources
Signaling plane
•MAP-Mobile application part(extension to SS7
of GSM)
Communication between SGSN and HLR or EIR
Used to transfer signaling information related to
location updates, user profiles and
handovers,routing information,
•BSSAP(Base station system Application part+)
Used to transfer signaling information between
the SGSN and the VLR
Transmission plane
Consist following interfaces
1]GPRS Backbone
2]BSS-SGSN Interface
3]Air interface
GPRS Backbone
•It is transmission between SGSN and GGSN
•User data packets and related signaling
information within the GPRS n/w are
encapsulated using the GPRS Tunneling
protocol(GTP)
•It Is used in both intra-PLMN and inter PLMN
•GTP packets carry the users data packets from
both IP and X.25 data n/w
GPRS Backbone
•Below GTP the standard protocol TCP or UDP
are used to transport the GTP packets within the
backbone n/w
•Ethernet,ISDN or ATM based protocol may be
used in the physical layer
•In GPRS backbone we have IP/X.25-over GTPover-UDP/TCP-over IP transport architecture
BSS-SGSN Interface
•It is divided in to following protocols
1]Sub-N/w Dependant Convergence ProtocolThe SNDCP is used to transfer data packets
between SGSN and MS its functionality includes
multiplexing, segmentation,compression and
decompression of user data
BSS-SGSN Interface
•Logical Link Control-LLC
This layer assures the reliable transfer of user
data across a wireless n/w
Base station system GPRS protocol(BSSGP)
Delivers routing and QOS related information
between BSS and SGSN
N/W service -This maps BSSGPS service request
to the appropriate frame relay service
Air Interface
•The air interface defines physical and data link
layer
•Data link layer:-the data link layer between the
MS and the BSS is devided into three sublayers
•1]LLC
•2]RLC
•3]MAC
•LLC-this layer provides a reliable logical link
between an MS and its assigned SGSN
•RLC-estabilish reliable link between MS and BSS
this include the segmentation and reassembly
•MAC-Acess Control
Physical Layer
Physical Link Layer
•Data encoding
•Data unit framing
•Detection and correction of physical medium
transmission errors.
Physical RF layer-Modulation and
demodulation
GPRS operations-1] GPRS Attach and
detach
When a MS is turned on, the first function it performs is GPRS
attach
It must register with an SGSN of the n/w
It implements logical link between MS and SGSN
N/w checks if the MS is authorised to use the service if yes it copies
the user profile from the HLR to the SGSN)
SGSN assigns a packet temporary Mobile subscriber identity(PTMSI) to the MS
After successful GPRS attach mobile station must apply for an
address to exchange the data for external network
Ex.If PDN is IP-IP address
This address is called PDP(Packet data protocol address)
For each session PDP context is created it contains PDP
type,requestedQOS,GGSN address.
This context stored in MS,SGSN,GGSN
•PDP Context Procedures
GGSN
MS
initiated
BSS
SGSN
GGSN
Packets from ext. nw.
PDU notification req.
PDU notification resp.
Request PDP Context activation
Activate PDP Context Request
Activate PDP Context Accept
Create PDP Context
Request
Create PDP Context
Response
•PDP address can be static or dynamic
•PDP c
•context activation procedure•The disconnection from GPRS network is called
GPRS detach all the resources are released
detach process can be initiated by the mobile
station or by the network
Mobility Management
•As a mobile station moves from one area to
another mobility management functions are
used .to track the location of MS within each
PLMN.
•SGSNS communicate with each other to update
the MS s location in the relevant registers
Mobility Management
•The mobile stations profiles are preserved in
the VLRs that are accessible to SGSN via local
MSC.
•A logical link is established between MS and the
SGSN at each PLMN
•When MS moves from SGSN area the logical
link is released.
Routing
GSM Location Area(LA) is divided into several
Routing Areas(RA)
RA consists of several cells
SGSN is informed when MS moves to a new RA
MS sends a “Routing Area Update Request” to its
assigned SGSN
Routing
When an MS that is in an active or a standby
state moves from one routing area to another
within the service area of one SGSN, it must
perform a routing update. The routing area
information in the SGSN is updated, and the
success of the procedure is indicated in the
response message.
Routing
A cell-based routing update procedure is
invoked when an active MS enters a new cell.
The MS sends a short message containing the
identity of the MS and its new location through
GPRS channels to its current SGSN. This
procedure is used only when the MS is in the
active state.
Routing
The inter-SGSN routing update is the most
complicated routing update. The MS changes
from one SGSN area to another, and it must
establish a new connection to a new SGSN. This
means creating a new logical link context
between the MS and the new SGSN and
informing the GGSN about the new location of
the MS.
Routing
Intra SGSN Routing Area Update
Inter SGSN Routing Area Update
Data services in GPRS
GPRS services are usually used in two modes
•Application Mode
•Tunneling mode
•Application mode1]in this mode the user will be using the GPRS
mobile phone to access the applications running
on the phone itself
2]all GPRS phone have WAP browser as an
embedded application it allow to browse WAP
sites
Data services in GPRS
Some GPRS devices support mobile execution
environment to develop a client application that run on
the device
These environments are Symbian and J2ME and
application are developed in C,C++,java.
2]Tunneling modeThis mode is for mobile computing where the user will
use the GPRS interface as an access to the network
The mobile phone will be connected to the device like
laptop or pda used as a modem to acess the wireless
data network
GPRS hanset(device)
GPRS terminal can be of three classes
ClassA=a terminal support GPRS data and other GSM
services such as SMS and voice simultaneously.SMS can
be received while a voice or data call is in progress.
Class B =terminal can monitor GSM and GPRS channel
simultaneously but support only one of these service
simultaniously and other service is on hold.SMS can be
received while a voice or data call is in progress.
Class C=terminal support only non simultaneous attach
terminal can make or receive calls from only the
manully selected network services the service that is
not selected is not reachable.
GPRS hanset(device)
Each handset will have a unique form factor with a
numeric keypad and small display,colour display with
camerabuilt in voice and web browsing capability,icon
drive screen.
GPRS bearer services
Bearer services of GPRS offer end-to-end packet
switched data transfer.
SMS-Short Message Service
WAP-Wireless Application Protocol
MMS-Multimedia messaging Service
GPRS Application
Generic ApplicationInformation service, internet access, email,web
browsing, sports score,wheather,flight information,
news headlines, prayer reminders, lottery
results,jokes,horoscopes,traffic information,banking
over wireless
GPRS specific applications1]chat
2]Multimedia service
3]VPN-many bank ATM machines use GPRS based
networks to connect ATM system with the banks server