8.3 GPRSmidas1.e-technik.tu-ilmenau.de/~webkn/Webdaten... · 8.3 GPRS GPRS –Session Management...
Transcript of 8.3 GPRSmidas1.e-technik.tu-ilmenau.de/~webkn/Webdaten... · 8.3 GPRS GPRS –Session Management...
Data Services in GSM I
• Data transmission standardized with only 9.6 kbit/s
▪ advanced coding allows 14.4 kbit/s
▪ not enough for Internet and multimedia
applications
• HSCSD (High-Speed Circuit Switched Data)
▪ mainly software update
▪ bundling of several time-slots to get higher AIUR
(Air Interface User Rate, e.g., 57.6 kbit/s using 4
slots @ 14.4)
▪ advantage: ready to use, constant quality, simple
▪ disadvantage: channels blocked for voice
transmission
Communication Networks - 8. Public Land Mobile Networks 364
8.3 GPRS
AIUR [kbit/s]
TCH/F4.8 TCH/F9.6 TCH/F14.4
4.8 1
9.6 2 1
14.4 3 1
19.2 4 2
28.8 3 2
38.4 4
43.2 3
57.6 4
8.3 GPRS
Data Services in GSM II
• GPRS (General Packet Radio Service)
▪ packet switching
▪ using free slots only if data packets ready to send (e.g., 50 kbit/s using 4 slots temporarily)
▪ standardization 1998, introduction 2001
▪ advantage: one step towards UMTS, more flexible
▪ disadvantage: more investment needed (new hardware)
• GPRS network elements
▪ GSN (GPRS Support Nodes): GGSN and SGSN
▪ GGSN (Gateway GSN)
❖ interworking unit between GPRS and PDN (Packet Data Network)
▪ SGSN (Serving GSN)
❖ supports the MS (location, billing, security)
▪ GR (GPRS Register)
❖ user addresses
Communication Networks - 8. Public Land Mobile Networks 365
GPRS: Quality of Service
Communication Networks - 8. Public Land Mobile Networks 366
8.3 GPRS
Reliability ClassLost SDU
ProbabilityDuplicate SDU
Probability
Out of Sequence SDU
Probability
Corrupt SDU Probability
1 10-9 10-9 10-9 10-9
2 10-4 10-5 10-5 10-6
3 10-2 10-5 10-5 10-2
DelayClass
SDU size 128 byte SDU size 1024 byte
mean 95 percentile mean 95 percentile
1 < 0.5 s < 1.5 s < 2 s < 7 s
2 < 5 s < 25 s < 15 s < 75 s
3 < 50 s < 250 s < 75 s < 375 s
4 unspecified
Examples for GPRS Device Classes
Communication Networks - 8. Public Land Mobile Networks 367
8.3 GPRS
Class Receiving Slots Sending SlotsMaximum
Number of Slots
1 1 1 2
2 2 1 3
3 2 2 3
5 2 2 4
8 4 1 5
10 4 2 5
12 4 4 5
GPRS User Data Rates in kbit/s
Communication Networks - 8. Public Land Mobile Networks 368
8.3 GPRS
CodingScheme
1 Slot 2 Slots 3 Slots 4 Slots 5 Slots 6 Slots 7 Slots 8 Slots
CS-1 9.05 18.1 27.15 36.2 45.25 54.3 63.35 72.4
CS-2 13.4 26.8 40.2 53.6 67 80.4 93.8 107.2
CS-3 15.6 31.2 46.8 62.4 78 93.6 109.2 124.8
CS-4 21.4 42.8 64.2 85.6 107 128.4 149.8 171.2
GPRS Architecture and Interfaces
Communication Networks - 8. Public Land Mobile Networks 369
8.3 GPRS
MS BSS GGSNSGSN
MSC
Um
EIREIR
HLR/GR
HLR/GR
VLRVLR
PDN
Gb Gn Gi
SGSN
Gn
GPRS Protocol Architecture
Communication Networks - 8. Public Land Mobile Networks 370
8.3 GPRS
Appl.
IP/X.25
LLC
GTP
MAC
Radio
MAC
RadioFR
RLC BSSGP
IP/X.25
FR
Um Gb Gn
L1/L2 L1/L2
MS BSS SGSN GGSN
UDP/TCP
Gi
SNDCP
RLC BSSGP IP IP
LLC UDP/TCP
SNDCP GTP
8.3 GPRS
GPRS – Session Management
• MN registers with GPRS network:
▪ GPRS-Attach to SGSN
• MN receives Packet Temporary Mobile Subscriber Identity P-TMSI
• Then, MN gets a Packet Data Protocol Address (PDP-Address), e.g. an IP-Address
• Finally, the PDP context is created in MN, SGSN, GGSN:
▪ PDP-Type (e.g. IPv4)
▪ PDP-Address of MN (e.g. 129.187.222.10)
▪ Desired Quality of Service (QoS Class)
▪ GGSN address that serves as gateway to the external network
Communication Networks - 8. Public Land Mobile Networks 371
GPRS – PDP Context Activation
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8.3 GPRS
MNMN SGSNSGSN GGSNGGSN
Security FunctionsSecurity Functions
8.3 GPRS
GPRS – Location Management
• Main task: retrieving the current location of a mobile subscriber
• Periodical Location Update messages to SGSN→ special state model:
Communication Networks - 8. Public Land Mobile Networks 373
IDLEIDLE
READYREADY
STANDBYSTANDBY
GPRSAttach
GPRSDetach
Ready Timer expiredor Force to Standby
Packetdelivery
Standby Timerexpired
GPRS – Intra-SGSN Routing Area Update
Communication Networks - 8. Public Land Mobile Networks 374
8.3 GPRS
Security FunctionsSecurity Functions
MNMN BSSBSS SGSNSGSN
GPRS – Inter-SGSN Routing Area Update
Communication Networks - 8. Public Land Mobile Networks 375
8.3 GPRS
Security FunctionsSecurity Functions
MNMN BSSBSSNewSGSNNewSGSN
OldSGSNOld
SGSNGGSNGGSN HLRHLR
MSC/VLR
MSC/VLR
GPRS – Data Flow and Segmenting
Communication Networks - 8. Public Land Mobile Networks 376
8.3 GPRS
HeaderHeader
HeaderHeader
Header Information
SegmentSegment SegmentSegment
SegmentSegment FCSFCS
SegmentSegment SegmentSegment
SegmentSegment BCSBCS
...
...
IP-Packet
SNDCP-Layer
LLC Frame LLC-Layer
RLC/MAC-Block
RLC/MAC-Layer
Internet
Communication Networks - 8. Public Land Mobile Networks 377
GPRS – Routing and Address Translation (I)
SGSN
SGSN
GGSNBSC
IP Packet(IP Source,IP Destination)
1.) Address translationaccording to PDP-context:IP-Destination →TID+SGSN-Address
1.) Address translationaccording to PDP-context:IP-Destination →TID+SGSN-Address
GTP (SGSN-Address,TID, IP Packet)
2.) Address translationaccording to PDP-context:TID → TLLI + NSAPI (+CI)
2.) Address translationaccording to PDP-context:TID → TLLI + NSAPI (+CI)
SNDCP (TLLI,NSAPI, IP Packet)
IP Packet
Communication Networks - 8. Public Land Mobile Networks 378
GPRS – Routing and Address Translation (II)
SGSN
SGSN
GGSNBSC
IP Packet(IP Source,IP Destination)
1.) Address translationaccording to PDP-context:IP Source → TLLI + NSAPI
1.) Address translationaccording to PDP-context:IP Source → TLLI + NSAPI
SNDCP (TLLI,NSAPI, IP Packet)
2.) Address translationaccording to PDP-context: TLLI + NSAPI → TID + GGSN
2.) Address translationaccording to PDP-context: TLLI + NSAPI → TID + GGSN
GTP (GGSN-Address,TID, IP Packet)
IP PacketInternet
GPRS – Air Interface
• GSM-based FDMA/TDMA-combination with 8 time slots per TDMA frame
• More flexible channel assignment scheme for GPRS:
▪ Multi-slot operations
▪ Separate assignment of uplink and downlink for asymmetric traffic
• Available channels dynamically assigned to both kinds of traffic (“Capacity on Demand”)
• Multiplexing several users over one physical GPRS channel
• GPRS „steals“ TCH capacity not used by CS traffic (https://www.slideshare.net/Pfedya/gprs-40919387):
Communication Networks - 8. Public Land Mobile Networks 379
8.3 GPRS
0
2
4
6
8
10
12
14
03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00
Number of CS Channels in Use(in Cell)
0
2
4
6
8
10
12
14
Number of CS channels in use
GPRS – Logical Channels
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8.3 GPRS
Group Channel Function Direction
Traffic Channels Packet DataTraffic Channel
PDTCH Packet Data Traffic MS BSS
Signaling Channels Packet BroadcastControl Channel
PBCCH Packet Broadcast Control MS BSS
Packet Common
Control Channel
(PCCCH)
PRACH Packet Random Access MS → BSS
PAGCH Packet Access Grant MS BSS
PPCH Packet Paging MS BSS
PNCH Packet Notification MS BSS
Packet DedicatedControl Channels
PACCH Packet Associated Control MS BSS
PTCCH Packet Timing Advance Control MS BSS
Interworking with IP Networks
Communication Networks - 8. Public Land Mobile Networks 381
8.3 GPRS
DNS DHCP
GPRS internalIP Network
Fire-wall
Intra-PLMNGPRS Backbone
InternetRou-ter
Gn Gn
Gi
SGSN GGSN
8.4 WAP
WAP - Wireless Application Protocol
• Goals
▪ Internet contents and enhanced services available for mobile end devices like cell phones or PDAs
▪ Independent standards for wireless networks
▪ Open standards: everybody may submit proposals for standardization
▪ Applications should be scalable and future-proof
• Platforms
▪ Many platforms must be supported:
❖ E.g. GSM (900, 1800, 1900), CDMA IS-95, TDMA IS-136, IMT-2000, UMTS, W-CDMA
• Forum
▪ WAP Forum, founded by (among others) Ericsson, Motorola, Nokia, Unwired Planet
▪ see http://www.wapforum.org
Communication Networks - 8. Public Land Mobile Networks 382
WAP – Standardization
• Browser
▪ „Micro-Browser”, comparable to familiar Internet browser
• Scripting Language
▪ Comparable to Java-Script, adapted to mobile enviroment
• WTA/WTAI
▪ Wireless Telephony Application (Interface): Access to telephone functionality
• Contents Formats
▪ Business cards (vCard)
▪ Calendar entries (vCalender)
• Protocol Stack
▪ Transport, Security and Session Layer
• Working Groups
▪ WAP Architecture Working Group
▪ WAP Wireless Protocol Working Group
▪ WAP Wireless Security Working Group
▪ WAP Wireless Application Working Group
Communication Networks - 8. Public Land Mobile Networks 383
8.4 WAP
WAP 1.x – Layers and Protocols
Communication Networks - 8. Public Land Mobile Networks 384
8.4 WAP
WAE includes e.g. WML (Wireless Markup Language), WML Script, WTAI
Bearer Services (GSM, Cellular Digital Packet Data, ...)
Security Layer (WTLS)
Session Layer (WSP)
Application Layer (WAE)
Transport Layer (WDP)TCP/IP,UDP/IP,
Phys. Media
SSL/TLS
HTML, Java
HTTP
Internet WAP
Transaction Layer (WTP)
Additional servicesand protocols
WCMP
A-SAP
S-SAP
TR-SAP
SEC-SAP
T-SAP
WAP – Network Elements
Communication Networks - 8. Public Land Mobile Networks 385
8.4 WAP
Mobile NetworkMobile NetworkFixed NetworkFixed Network
WAPProxyWAPProxy
WTAServerWTA
Server
Filter/WAPProxy
Filter/WAPProxyWeb
ServerWeb
Server
FilterFilter
TelephoneNetwork
Internet
Binary WML: Binary data format for clients
Binary WML
Binary WML
Binary WML
HTML
HTML
HTML WML
WMLHTML
Wireless Application Environment: Logical Model
Communication Networks - 8. Public Land Mobile Networks 386
8.4 WAP
Original ServerOriginal Server
webserver
otherservers
GatewayGateway ClientClient
otherWAE
user agents
WMLuser agent
WTAuser agent
Coder&
Decoder
codedrequest
request
coded reply
reply
pushcontents
codedpushcontents
Wireless Telephony Application: Logical Architecture
Communication Networks - 8. Public Land Mobile Networks 387
8.4 WAP
AdditionalServer
ClientClient
Repository
WTA-User-Agent
WTA-GatewayWTA-Gateway
Coder&
Decoder
Other TelephoneNetworks
WTA-ServerWTA-Server
WTA & WMLServer
WML-Scripts
WML-Stack
WTA-Services
MobileNetwork
ExternalServer
Secure ProviderNetwork
Device Spec.Functions
Fire-wall
Example Voice Box
Communication Networks - 8. Public Land Mobile Networks 388
8.4 WAP
Service Indication
WTA-User-Agent WTA-Server Mobile Network Voice Box
Create Content
Presentation; User Selection
Connection Setup
Accept Call
Voice connection
Indicate new voice message
Request to deliver voice message
Connection establishment
Call acceptance Call acceptance
WTA-Gateway
Push URL
Indication; User Selection
WSP GetHTTP Get
Reply with ContentWMLBinary WML
WSP GetHTTP Get
Reply with Card for CallWMLBinary WML
Waiting for Call
Connection establishment
Possible Protocol Stacks for WAP 1.x
Communication Networks - 8. Public Land Mobile Networks 389
8.4 WAP
WAE
WSP
WTP
UDP
IP(GPRS, ...)
WDP
non IP(SMS, ...)
WTLS
WAE user agentWAP Standard
Not part of WAP
WTP
UDP
IP(GPRS, ...)
WDP
non IP(SMS, ...)
WTLS
UDP
IP(GPRS, ...)
WDP
non IP(SMS, ...)
WTLS
Transaction-basedApplications
Datagram-basedApplications
typical WAP Application based on complete protocol stack
Simple data transfer with or without security mechanisms
8.4 WAP
WAP 2.0 (July 2001)
• New▪ XHTML
▪ TCP with „Wireless Profile“
▪ HTTP
• Innovative Applications▪ Color graphics
▪ Animation
▪ Download of big files
▪ Location-based services
▪ Synchronization with PIMs
▪ Pop-up/context-sensitive menus
• Goal▪ Integration of WWW, Internet, WAP, i-mode
Communication Networks - 8. Public Land Mobile Networks 390
WAP 2.0 Architecture
Communication Networks - 8. Public Land Mobile Networks 391
8.4 WAP
ServiceLocalization
SecurityServices
Ap
plic
atio
nFr
amew
ork
Pro
toco
l Fra
me
wo
rk
External Services
EFI
External Services
EFI
Provisio-ning
Provisio-ning
NavigationDiscoveryNavigationDiscovery
ServiceLookupServiceLookup
Crypto-LibrariesCrypto-Libraries
Authenti-cation
Authenti-cation
Identifica-tion
Identifica-tion
PKIPKI
SecureTransport
SecureTransport
SecureBearersSecureBearers
Sess
ion
Sess
ion
Tran
sfer
Tran
sfer
Tran
spo
rtTr
ansp
ort
Bea
rer
Bea
rer
Multimedia Messaging (Email)
Multimedia Messaging (Email)
WAE/WTA User Agent (WML, XHTML)
WAE/WTA User Agent (WML, XHTML)
ContentFormatsContentFormats
PushPush
IPv4IPv4
IPv6IPv6
CSDCSD
SMSSMS
USSDUSSD
FLEXFLEX
GUTSGUTS
MPAKMPAK
......
......
Datagrams(WDP, UDP)Datagrams(WDP, UDP)
Connections(TCP with
wireless profile)
Connections(TCP with
wireless profile)
Hypermedia Transfer
(WTP+WSP, HTTP)
Hypermedia Transfer
(WTP+WSP, HTTP)
Strea-mingStrea-ming
MMSMessa-
ges
MMSMessa-
ges
Push OTAPush OTA
Capability NegotiationCapability
Negotiation
Synchronization Synchronization
CookiesCookies
WAP 2.0 Protocol Stacks
Communication Networks - 8. Public Land Mobile Networks 392
8.4 WAP
TrägerWDPWTLSWTPWSPWAE
WAP Device
TrägerWDPWTLSWTPWSP
IPTCPTLS
HTTP
IPTCPTLS
HTTP
WAEWeb ServerWAP Gateway
WAP 1.x Server/Gateway/Client
IPTCP‘TLS
HTTPWAE
WAP Device
IPTCP‘
IPTCP
IPTCPTLS
HTTPWAE
Web ServerWAP Proxy
WAP Proxy with TLS-Tunneling
IPTCP‘HTTPWAE
WAP Device
IPTCP‘
IPTCP
IPTCP
WAEWeb ServerWAP Proxy
WAP HTTP Proxy with adapted TCP
HTTP HTTP HTTP
IPTCP‘HTTPWAE
WAP Device
IP IP IPTCP
WAEWeb-Server
IP Router
WAP direct access
HTTP