Lecture Overview

1
Lecture Overview

• Data in Wireless Cellular Systems GSM and GPRS

2
Security in GSM

• Security services
• access control/authentication
• SIM (Subscriber Identity Module) secret PIN
  (personal identification number)
• confidentiality
• voice and signaling encrypted on the wireless
  link (after successful authentication)
• anonymity
• temporary identity TMSI (Temporary Mobile
  Subscriber Identity)
• newly assigned at each new location update (LUP)
• encrypted transmission
• 3 algorithms specified in GSM
• A3 for authentication (secret, open interface)
• A5 for encryption (standardized)
• A8 for key generation (secret, open interface)

• secret
• A3 and A8 available via the Internet
• network providers can use stronger mechanisms

3
GSM - Authentication
4
GSM - Key Generation and Encryption
5
GSM Security

• equipment identity checking
• Equipment Identity Register (EIR) maintains
  database related to mobile equipment (hardware)
  identified by International Mobile Equipment
  Identity (IMEI)
• IMEI consists of Type Approval Code (granted when
  mobile station type passes type approval testing
  to ensure mobile station behaves properly), Final
  Assembly Code (indicating manufacturing plant),
  and the equipment serial number
• EIR stores three lists of IMEIs
• white list contains ranges of IMEIs of type
  approved mobile stations
• black list contains IMEIs which are stolen or
  malfunctioning, and are subsequently barred
• gray list contains IMEIs which should be
  supervised for possible malfunctions

6
GSM Voice and Data Architecture Note here PSTN
should be connected to SS7 network not directly
connected to MSC/VLR
7
Data Services in GSM

• 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)
• already standardized
• bundling of several time-slots to get higher AIUR
  (Air Interface User Rate)(e.g., 57.6 kbit/s using
  4 slots, 14.4 each)
• advantage ready to use, constant quality, simple
• disadvantage channels blocked for voice
  transmission

8
GSM Data Properties

• Circuit-switched operation
• uplink and downlink channels allocated for a user
  for entire call period
• busy user uses only one direction of link
  (typically), so 50 of resources are wasted
• user pays for the connection time, not for the
  amount of data
• bad connections - more retransmissions - make
  more money for operator
• pay even if no data is transmitted
• connection establishment time 20-25 seconds
• bad for short-lived transactions
• capacity 9.6 kbps (channel coding designed for
  worst-case radio situation)
• connections to any modem service in PSTN

9
GSM Data Properties Evaluation

• Circuit-switched data is good for cases when
  continuous data flow is needed/required
• Billing is based on time, not amount of data
• Limited number of mobiles can be supported per
  carrier (8 channels)
• Circuit-switched data is not optimal for
• packet-based protocols such as IP
• bursty traffic
• unbalanced traffic (using mainly one channel
  direction)
• ? Packet switched service is needed for GSM
• ? GPRS standardization was started

10
GPRS

• General Packet Radio Service GPRS, 2.5 generation
  wireless systems

11
GPRS architecture

• stands for General Packet Radio Service.
• GPRS is packet switched network developed as the
  extension of the GSM network.
• MS, BSS, MSC/VLR and HLR in the GSM network are
  modified for GPRS (e.g. HLR is enhanced with GPRS
  subscriber info.)
• one step ahead of HSCSD (High Speed Circuit
  Switched Data), and a step towards
  third-generation (3G) networks.

12
GPRS

• GPRS is a packet-switching technology for GSM
  networks. Information sent on a GPRS network is
  split into separate "packets" before it is
  transmitted and reassembled at the receiving end.
  
• One of the advantages of GPRS is its ability to
  provide instant connection where information can
  be sent and received immediately. Unlike the
  current GSM network where you have to "dial up"
  and wait for a connection to be established, GPRS
  allows users to be "always connected" to the
  network.

13
GPRS Cont

• Theoretically, a GPRS connection can provide a
  data transmission speed of up to 171.2Kbps
  (approximately three times that of a fixed-line
  56K dial-up) if all eight time slots are used.
• GPRS's rival, HSCSD, can achieve up to 57.6Kbps.
• it is unlikely that network operators will let a
  single user use up all the time slots (8 x 21.4
  Kbps)

14
A comparison of data transfer speed (in Kbps)
56K dial up GSM HSCSD (max speed) GPRS (Max speed) GPRS (Realistic speed)
56 9.6 56K 171. 2 43 to 56
15
What GPRS can do for you?

• GPRS allows you to have an "always on" connection
  to the network.
• Anyone who needs wireless mobile data access will
  benefit from GPRS
• With GPRS, you can access your email, browse the
  Internet, transfer/share documents, and remotely
  access your office's Local Area (LAN).
• Even home automation is possible when household
  appliances are equipped with Internet Protocol
  (IP)!

16

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(No Transcript)
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Architecture - GSM with GPRS
GMSC
PSTN
Circuit Switched Traffic
MSC
MAP
A-bis
A
HLR/AUC GPRS Register
Peer Elements
BSC
BTS
GPRS Register H/VLR
PCU
MAP
Gb
SGSN
SGSN
Packet Traffic
Gn
GGSN
GGSN
Gi
19
GPRS Architecture Elements
20
E- Commerce Over GPRS

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GPRS Charging Requirements
Single access point to the billing
system Pre-processing charging data to reduce the
load on the network billing system Future-proof
for hot-billing and pre-paid Reliable storage
for CDRs Easy charging data error detection
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GPRS Architecture Services

• Packet-based access to data networks
• Internet (IPv4, IPv6)
• X.25
• Private/public networks
• Fast carrier of SMSs
• Security (operator, user, identity, data)
• Mobility management

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GPRS Architecture and Interfaces
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GPRS Protocol Stack
SNDCP SUBNETWORK DEPENDENT CONVERGENCE PROTOCOL
LLC LOGICAL LINK PROTOCOL RLCRADIO LINK
CONTROL BSSGP BSS GPRS PROTOCOL FRFRAME RELAY
GTP GPRS TUNNELING PROTOCOL
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GPRS Radio Link ProtocolsFYI
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GPRS Radio Interface

• Logical channels
• packet common control channels (PCCCH)
• packet random access channel (PRACH)
• packet paging channel (PAGCH)
• packet access grant channel (PAGCH)
• packet notification channel (PNCH)
• packet broadcast control channel (PBCCH)
• packet data traffic channel (PDTCH)
• data rates 9.05 to 21.4 kbps, depending on
  channel coding
• packet associated control channel (PACCH)
• Physical channels
• PDTCH is mapped to one physical channel
• dynamic or permanent channel allocation for GPRS
  possible
• if no PCCCH possible, MSs park on CCCH (common
  control channel)

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Logical Channels in GPRS
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Logical Channels in GPRS Cont

• Uplink channel allocation (one or two steps)

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GPRS New Radio Interfaces

• GPRS can use various radio interfaces
• DECT, EDGE, UMTS, IEEE 802.11, IrDA (infrared)
• Radio should
• operate using packet mode
• provide identifier of the downlink packets
• provide reasonable residual error rates
• Wish list for radio services
• fast channel allocation and release
• battery saving mechanism (sleep mode)
• adaptive coding (depending on radio quality)
• just one (efficient) paging channel that can be
  listened to also when transferring data

30
GPRS Evolution

• GPRS is standardized in SMG (Specilized Mobile
  Group) in ETSI (see also http//www.etsi.fr,
  http//www.wapinsight.com/what_is_gprs.htm
• Standard was approved March/June 1998
• changes are still expected
• Some issues delayed for later consideration
• testing (type approval), charging, .
• GPRS phase 1 Release 97
• basic set of GPRS functionality
• optional features

31
2G ? 3G Evolution Convergence
32
Benefits of Globally Harmonized 3G Networks

• Increased 3G penetration and usage
• Manufacturers development costs spread out
  across a larger installed base
• Ability for customers to roam with their services
  across regions, countries and systems
• Increased ability of the Information Technology,
  Internet and Personal Computer industries to
  provide mobile applications, solutions and
  subscriber devices
• Smooth and compatible evolution path from
  existing 2G infrastructures

33
UMTS and IMT-2000

• Proposals for IMT-2000 (International Mobile
  Telecommunications)
• UWC-136, cdma2000, WP-CDMA, TD-SCDMA
• UMTS (Universal Mobile Telecommunications System)
  from ETSI

34
IMT-2000 Vision
35

• The ITU has set down the minimum requirements to
  be an IMT-2000 system.
• We're talking about 144 Kb/s in your macrocells.
  A macrocell can be anything up to 10 kilometers,
  and that would be your vehicular speeds.
• If you are in a pedestrian environment, then you
  can get up to 384 Kb/s and again we're shrinking
  the cell to enable us to get up to those higher
  data rates, something less than 300 meters.
• If you want to get up to 2 Mb/s, you need to
  shrink the cell, even though seeming to be very,
  very close to the cell to enable those higher
  data rates. And so here we're talking about very
  small cells, picocells, very, very close. Your
  use is going to be very, very close to the base
  station to enable those data rates.

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Cellular/PCS Data Speed Evolution (to IMT-2000)

37
IMT-2000 Vision

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UMTS

• UMTS
• UTRA (was UMTS, now Universal Terrestrial Radio
  Access)
• enhancements of GSM
• EDGE (Enhanced Data rates for GSM Evolution) GSM
  up to 384 kbit/s
• CAMEL (Customized Application for Mobile Enhanced
  Logic)
• VHE (virtual Home Environment)
• fits into GMM (Global Multimedia Mobility)
  initiative from ETSI
• requirements
• min. 144 kbit/s rural (goal 384 kbit/s)
• min. 384 kbit/s suburban (goal 512 kbit/s)
• up to 2 Mbit/s urban

39
Licensing Example UMTS in Germany, 18. August
2000

• UTRA-FDD
• Uplink 1920-1980 MHz
• Downlink 2110-2170 MHz
• duplex spacing 190 MHz
• 12 channels, each 5 MHz
• UTRA-TDD
• 1900-1920 MHz,
• 2010-2025 MHz
• 5 MHz channels
• Coverage 25 of the population until 12/2003,
  50 until 12/2005

Sum 50.81 billion
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types of traffic

• Conversational class (voice, video telephony,
  video gaming)
• Streaming class (multimedia, video on demand,
  webcast)
• Interactive class (web browsing, network gaming,
  database access)
• Background class (email, SMS, downloading)

41
UMTS Architecture
42
service objectives

• support Universal Personal Telecommunications
  (UPT),
• fixed network service for personal mobility,
  allowing registration and deregistration at any
  terminal
• support wide range of terminal type
• broad range of customizable telecommunication
  services up to 2 Mbps
• operation in, and roaming between, different
  operating environments
• - sparse, rural, suburban, urban
• indoor/outdoor
• residential/business
• pedestrian/vehicular

43
service objectives (2)

• Combine range of existing wireless systems
  (cellular, cordless, mobile data, paging) to
  share infrastructure costs and harmonize services
• Allow flexible and rapid creation of new services
• Efficient usage of spectrum resources
• Three major 3G terrestrial Standard
• cdma2000 A Wideband CDMA technology backward
  compatible with cdmaOne (IS-95 based) systems
• W-CDMA A Wideband CDMA Technology backward
  compatible with GSM
• UWC-136 A Wideband TDMA technology backward
  compatible with IS-54 /IS-136

44
Key Technology concept in 3G(1)

• Broadband Generally, compares bandwidth relative
  to narrowband or wideband. For example, video is
  considered to be broadband relative to voice .
• In telecommunications transmission systems, any
  transmission system that operates at rates
  greater than the primary rate of 1.5 Mb/s in the
  U.S. or 2.0 Mb/s internationally. (However, many
  consider 1.5-45 Mb/s to be wideband, and consider
  broadband as being 45 Mb/s and greater.)

45
Key Technology concept in 3G(2)

• Packet Vs Cirsuit
• A packet mode is when I share my RF resource as
  opposed to a circuit-switched mode, which is one
  that's dedicated to me
• A block or grouping of data (PDU) usually defined
  at Layer 3 that is treated as a single unit
  within a communication network. Normally ranges
  from 10 bytes to several thousand bytes in size,
  and contains a header with certain control
  information. Connectionless protocols (such as
  IP) generally refer to packets as datagrams. The
  header of the datagram will contain the address
  of the desired destination.
• In connection-oriented protocols (such as X.25),
  information is switched to the proper
  destination. In order to uniquely associate the
  transmitted information with the appropriate
  virtual connection, the header of each packet
  contains a unique (to that physical interface)
  virtual connection identifier.

46
Circuit and Packet Mode

• a circuit mode access and a packet mode access.
• In a circuit mode, for example in a voice call, I
  have a dedicated channel for the duration of my
  call. When sending data in a circuit mode
  connection, data can be sent whenever we want.
  Because that channel is dedicated to us, no one
  else is using it. So we do not need approval to
  transmit data.
• Compare that now with a packet mode. A packet
  mode is when we are sharing our RF resource
  sharing a channel. So we're going to take turns
  in using the channel. If we're in a shared
  environment and we're taking turns, we need
  something to tell us when it's our turn When is
  it your turn, when is it my turn, to use our
  shared channel? And for that we're going to use
  the MAC protocol. The Medium Access Control
  protocol is going to say, "It's your turn to use
  it. Now you stop now it's my turn to use it."
  And this is what's new when we start looking at
  3G.
• So when we talk about cdma2000 and UWC-136, we're
  talking about a packet mode introducing the MAC
  protocol. We also talk about that in W-CDMA but
  notice that part of GPRS in GSMGPRS is also a
  packet mode of operation and also includes the
  MAC protocol.

47
UMTS Interacting Domain

• A UMTS network consist of three interacting
  domains
• Core Network CNThe main function of the core
  network is to provide switching, routing and
  transit for user traffic. Core network also
  contains the databases and network management
  functions.
• UMTS Terrestrial Radio Access Network (UTRAN)
• and User Equipment (UE).

48
UMTS Architecture
49
UMTS Architecture

• The basic Core Network architecture for UMTS is
  based on GSM network with GPRS
• The UTRAN provides the air interface access
  method for User Equipment.
• Base Station is referred as Node-B and control
  equipment for Node-B's is called Radio Network
  Controller (RNC).

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System Areas

• UMTS systems (including satellite)
• Public Land Mobile Network (PLMN)
• MSC/VLR or SGSN
• Location Area
• Routing Area (PS domain)
• UTRAN Registration Area (PS domain)
• Cell
• Sub cell

51
Core Network

• The Core Network is divided in circuit switched
  and packet switched domains.
• Circuit switched elements are Mobile services
  Switching Centre (MSC), Visitor location register
  (VLR), and Gateway MSC
• packet switched elements are Serving GPRS Support
  Node (SGSN) and Gateway GPRS Support Node (GGSN).
  Some network elements, like EIR HLR and AUC, are
  shared by both domains.
• The Asynchronous Transfer Mode (ATM) is defined
  for UMTS core transmission. ATM Adaptation Layer
  type 2 (AAL2) handles circuit switched connection
  and packet connection protocol AAL5 is designed
  for data delivery.The architecture of the Core
  Network may change when new services and features
  are introduced. Number Portability DataBase
  (NPDB) will be used to enable user to change the
  network while keeping their old phone number.
  Gateway Location Register (GLR) may be used to
  optimize the subscriber handling between network
  boundaries. MSC, VLR and SGSN can merge to become
  a UMTS MSC.

52
Radio Access

• Wide band CDMA technology was selected to for
  UTRAN air interface WCDMA has two basic modes of
  operation Frequency Division Duplex (FDD) and
  Time Division Duplex (TDD)
• The functions of Node-B (Base Station) are
• Air interface Transmission / Reception
• Modulation / Demodulation
• CDMA Physical Channel coding
• Error Handing
• Closed loop power control

53
The functions of RNC are

• Admission control
• Congestion control
• System information broadcasting
• Radio channel encryption
• Handover
• Radio network configuration
• Channel quality measurements
• Radio carrier control
• Radio resource control
• Data transmission over the radio interface
• Outer loop power control (FDD and TDD)
• Channel coding
• Access control

54
User Equipment

• The UMTS standard does not restrict functionality
  of the UE in any way
• UMTS identity types are taken directly from GSM
  specifications
• International Mobile Subscriber Identity (IMSI)
• Temporary Mobile Subscriber Identity (TMSI)
• Packet Temporary Mobile Subscriber Identity
  (P-TMSI)
• Temporary Logical Link Identity (TLLI)
• Mobile station ISDN (MSISDN)
• International Mobile Station Equipment Identity
  (IMEI)
• International Mobile Station Equipment Identity
  and Software Number (IMEISV

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3G and LAN Data Speed
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UMTS Services

• UMTS offers
• teleservices (like speech or SMS)
• and bearer services, which provide the
  capability for information transfer between
  access points. It is possible to negotiate and
  renegotiate the characteristics of a bearer
  service at session or connection establishment
  and during ongoing session or connection. Both
  connection oriented and connectionless services
  are offered for Point-to-Point and
  Point-to-Multipoint communication
• Offered data rate targets are
• 144 kbits/s satellite and rural outdoor
• 384 kbits/s urban outdoor
• 2048 kbits/s indoor and low range outdoor.

57
UTRAN architecture
RNC Radio Network Controller RNS Radio Network
Subsystem
RNS
UE1
Iub
Node B
Iu
RNC
CN
UE2
Node B
Node B
UTRAN comprises several RNSs Node B can support
FDD or TDD or both RNC is responsible for
handover decisions requiring signalingto the
UE Cell offers FDD or TDD
UE3
Iur
Node B
Iub
Node B
RNC
Node B
Node B
RNS
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Core network protocols
VLR
MSC
GMSC
GSM-CS backbone
RNS
HLR
RNS
SGSN
GGSN
Layer 3 IP
GPRS backbone (IP)
Layer 2 ATM
SS 7
Layer 1 PDH, SDH, SONET
UTRAN
CN
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Core network architecture
VLR
BSS
Abis
BTS
Iu
BSC
MSC
GMSC
PSTN
Node B
BTS

• IuCS

AuC
HLR
EIR
GR
Node B
Iub
Node B
RNC
SGSN
GGSN
Gi
Gn
Node B
Node B

• IuPS

CN
RNS
60
Core network

• The Core Network (CN) and thus the Interface Iu,
  are separated into two logical domains
• Circuit Switched Domain (CSD)
• Circuit switched service incl. signaling
• Resource reservation at connection setup
• GSM components (MSC, GMSC, VLR)
• IuCS
• Packet Switched Domain (PSD)
• GPRS components (SGSN, GGSN)
• IuPS
• Release 99 uses the GSM/GPRS network and adds a
  new radio access!
• Helps to save a lot of money
• Much faster deployment
• Not as flexible as newer releases (5, 6)

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UMTS protocol stacks
IuCS
UTRAN
3G MSC
Uu
UE
apps. protocols
RLC
SAR
RLC
SAR
Circuit switched
MAC
MAC
AAL2
AAL2
radio
radio
ATM
ATM
Uu
IuPS
UE
UTRAN
3G SGSN
Gn
3G GGSN
apps. protocols
IP, PPP,
IP, PPP,
IP tunnel
Packet switched
GTP
PDCP
GTP
PDCP
GTP
GTP
RLC
UDP/IP
RLC
UDP/IP
UDP/IP
UDP/IP
MAC
MAC
AAL5
AAL5
L2
L2
radio
radio
ATM
ATM
L1
L1
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UMTS services (originally)

• Data transmission service profiles
• Virtual Home Environment (VHE)
• Enables access to personalized data independent
  of location, access network, and device
• Network operators may offer new services without
  changing the network
• Service providers may offer services based on
  components which allow the automatic adaptation
  to new networks and devices
• Integration of existing IN services