Introduction to Wireless Metropolitan Area Networks (WMAN) topics like 2G, WAP, 3G GPRS, 4G, WiMAX, LTE, and security concerns.

1. Wireless Metropolitan
Area Networks
CS4492 Wireless and Broadband Networking
Dilum Bandara
Dilum.Bandara@uom.lk
Some slides extracted from GSM & GPRS Primer by By Erick O’Connor

2. Outline
 2G
 WAP
 3G
 GPRS
 4G
 WiMAX
 LTE
 Security
2

3. Global System for Mobile (GSM)
 For voice services
 TDMA-based, circuit switching, digital cellular
system
 Frequency bands
3

4. AUC Authentication Centre
BSC Basestation Controller
BTS Basestation Transceiver
EIR Equipment Identity Register
GMSC Gateway Mobile Switching Centre
HLR Home Location Register
ISC International Switching Centre
ISDN Integrated Services Digital Network
MSC Mobile Switching Centre
PDN Packet Data Network (X25)
PSTN Public Switched Telephony Network
SIWF Shared Interworking Function
VLR Visitor Location Register
XCDR Transcoder (16 / 64kbps coding)
Basic GSM Network Elements
BTS
BSC
BSC
BTS
BTS
MS + SIM
XCDR
Radio Subsystem
GMSC
ISC
PSTN
ISDN
PDN
MSC
SIWF
Network Subsystem
VLR
EIR
AUC
HLR
User Data &
Authentication

5. Basic GSM Network Elements (Cont.)
 Mobile Equipment/Station
 Subscriber Identity Module (SIM)
 Base Transceiver Station (BTS)
 Wireless transmission
 Wireless channel encryption
 Conversion between wired & wireless signals
 Frequency hopping
 Base Station Controller (BSC)
 Managing wireless network
 Monitoring BTS
 Wireless link distribution between MS & BTS
 Communication connection & disconnection
 MS location, handover, & paging
 Voice encoding, transecoding (TC), rate adaptation 5

6. Basic GSM Network Elements (Cont.)
 Mobile Service Switching Center (MSC)
 All switching functions
 Manages necessary radio resources
 Updating location registration
 Inter-working with other networks
 Home Location Register (HLR)
 Manages mobile subscribers database
 Subscriber information
 Visitor Location Register (VLR)
 Dynamically stores subscriber information needed to handle
incoming/outgoing calls
 Mobile station roaming number
 Authentication Center(s) (AUC)
 Provide authentication key used for authorizing the subscriber 6

7. GSM Data Frame Structure
 2 data frames per connection
 Shared data rate of 270 Kbps or 33.85 Kbps per user 7

8. WAP – Wireless Application Protocol
 Goals
 Deliver Internet content & enhanced services to mobile devices
& users
 Mobile phones, PDAs
 Independence from wireless network standards
 Platforms
 GSM (900, 1800, 1900), CDMA IS-95, TDMA IS-136, 3G
systems (IMT-2000, UMTS, W-CDMA, cdma2000 1x EV-DO),
etc.
 Forum
 WAP Forum  Open Mobile Alliance
 Co-founded by Ericsson, Motorola, Nokia, Unwired Planet
8

9. WAP – Scope of Standardization
 Browser
 “Micro browser”, similar to existing, well-known browsers in
desktops
 Script language
 Similar to Java Script, adapted to mobile environment
 WTA/WTAI
 Wireless Telephony Application (Interface)
 Access to all telephone functions
 Content formats
 E.g., business cards (vCard), calendar events (vCalendar)
 Protocol layers
 Transport layer, security layer, session layer, etc.
9

10. WAP – Network Elements
10
Wireless Network
Fixed Network
WAP
proxy
WTA
server
filter/
WAP
proxy
web
server
filter
PSTN
Internet
Binary WML: binary file format for clients
Binary WML
Binary WML
Binary WML
HTML
HTML
HTML WML
WML
HTML

11. WAP Logical Model
11
Origin Servers
web
server
other content
server
Gateway Client
other
WAE
user agents
WML
user agent
WTA
user agent
encoders
&
decoders
encoded
request
request
encoded
response
with
content
response
with
content
push
content
encoded
push
content

12. WAP 1.x – Reference Model & Protocols
12
Bearers (GSM, CDPD, ...)
Security Layer (WTLS)
Session Layer (WSP)
Application Layer (WAE)
Transport Layer (WDP)
TCP/IP,
UDP/IP,
media
SSL/TLS
HTML, Java
HTTP
Internet WAP
WAE comprises WML (Wireless Markup Language), WML Script, WTAI etc.
Transaction Layer (WTP)
additional services
and applications
WCMP
A-SAP
S-SAP
TR-SAP
SEC-SAP
T-SAP

13. WAP 2.0 (July 2001)
 Integration of WWW, Internet, WAP, i-mode
 New for developers
 XHTML
 TCP with “Wireless Profile”
 HTTP
 New applications
 Color graphics
 Animation
 Large file download
 Location based services
 Synchronization with PIMs
 Pop-up/context sensitive menus
13

14. WAP 2.0 Architecture
14
Service
discovery
Security
services
Application
framework
Protocol
framework
External
services EFI
Provisioning
Navigation
Discovery
Service
Lookup
Crypto
libraries
Authenti-
cation
Identification
PKI
Secure
transport
Secure
bearer
Session
Transfer
Transport
Bearer
Multimedia Messaging
(Email)
WAE/WTA User Agent
(WML, XHTMLMP)
Content
formats
Push
IPv4
IPv6
CSD
SMS
USSD
FLEX
GPRS
MPAK
...
...
Datagrams
(WDP, UDP)
Connections
(TCP with
wireless profile)
Hypermedia transfer
(WTP+WSP, HTTP)
Strea-
ming
MMS
Push
OTA
Capability Negotiation
Synchronisation
Cookies

15. Criticism for WAP
 Odd WML language
 WML cut users off from HTML
 Under-specification of terminal requirements
 Compliant devices would not necessarily interoperate
properly
 Constrained user interface capabilities
 Lack of good authoring tools
 No easy way to publish content that would
interoperate flawlessly with many models
 Lack of user agent profiling tools
 Web server didn’t know who the client is 15

16. General Packet Radio Service (GPRS)
 Added to GSM to support data services
 2.5G
 Aggregate data rate of 72.4 Kbps
 Packet oriented approach
 Dynamic, on demand, & bundled time-slot
allocation
 Designed to coexist with voice services
 Supports
 IPv4 & IPv6
 TCP & UDP
 High overhead 16

17. BG Border Gateway
BSC Basestation Controller
BTS Basestation Transceiver
GGSN Gateway GPRS Support Node
HLR Home Location Register
PCU Packet Control Unit
PDN Packet Data Network (X25)
PLMN Public Land Mobile Network
SM-SC Short Message Service Centre
SGSN Serving GPRS Support Node
VLR Visitor Location Register
GPRS Network Elements
17
HLR
VLR
BTS
BSC
BSC
BTS
BTS
GPRS MS + SIM
PCU
Other GPRS
PLMN
GGSN
SGSN
PDN
GGSN
SM-SC
BG

18. BSSGP Basestation System GPRS Protocol
GSM RF Radio Frequency
GTP Gateway Tunnelling Protocol
LLC Logical Link Control
MAC Medium Access Control
RLC Radio Link Control
SNDCP Subnetwork Dependent Convergence Protocol
Protocol Layers in GPRS
18
Laptop
/ PDA
GPRS MS BSS SGSN GGSN
Application Protocol (http / ftp)
Transmission Control Protocol (TCP)
GSM RF
IP
MAC
RLC
LLC
SNDCP
GSM
RF
MAC
RLC
L1 bis
Network
Service
BSSGP
L1 Bis
Network
Service
BSSGP
LLC
SNDCP
L1
L2
IP
UDP /
TCP
GTP
L1
L2
IP
UDP /
TCP
GTP
IP
TCP
IP
TCP
IP
TCP

19. Generations
19
• D-AMPS – Digital - Advanced
Mobile Phone System
• EDGE – Enhanced Data rates
for GSM Evolution
• HSCSD – High-Speed Circuit-
Switched Data
• PDC – Personal Digital Cellular
• TD-SCDMA –Time Division
Synchronous Code Division
Multiple Access
• UMTS – Universal Mobile
Telecommunications System
• WCDMA – Wideband CDMA

20. GSM Vs. CDMA
20

21. Evolved High-Speed Packet Access
(HSPA+)
 Enhances widely used W-CDMA (UMTS) based 3G
networks
 UMTS – Universal Mobile Telecommunications System
 168 Mbps uplink and 22 Mbps downlink peak speeds
 With MIMO & 64QAM
 Only when close to base station
 50 ms latency
 Enable migration to 4G speeds without changing radios
 Affordable & incremental upgrade to existing HSPA networks
21

22. HSPA+
22
Source: http://www.4gamericas.org/index.cfm?fuseaction=page&sectionid=248

23. 3G vs. 4G
23
Source: http://www.theneweconomy.com/infographics/infographics-tesy

24. 4G
 Provides mobile ultra-broadband Internet access
 Applications
 Mobile web access, IP telephony, gaming, HD mobile TV, video
conferencing, 3D television, & Cloud Computing
 Systems that support International Mobile
Telecommunications-Advanced (IMT-Advanced) standard
 2 commercial deployments
 Worldwide Interoperability for Microwave Access (WiMAX) – since
2006
 Long Term Evolution (LTE) – since 2009
 These are not quite 4G, but IEEE 802.16m & LTE-Advanced are
 Use wideband OFDM & MIMO
24

25. International Mobile Telecommunications-
Advanced (IMT-Advanced)
 Entirely IP based packet switching
 IPv6 based
 Interoperability with existing wireless standards
 Goals
 100 Mbps for highly mobile systems – on cars, busses, trains
 1 Gbps for low mobile systems – pedestrians & stationary
 Dynamically share & use network resources to support
more simultaneous users per cell
 Seamless connectivity & global roaming across multiple
networks with smooth handovers
 High QoS for multimedia support
25

26. Worldwide Interoperability for
Microwave Access (WiMAX)
 IEEE 802.16 – Wireless MANs
 Goal
 Provide high-speed Internet access to home & business
subscribers, without wires
 30 - 40 Mbps
 High data rate or long distance but not both
 More enegy efficient than LTE & HSPA+
26

27. Speed vs. Mobility of Wireless
Systems
27

28. Long Term Evolution (LTE)
 Based on GSM/EDGE & UMTS/HSPA
 Downlink
 Peak 300 Mbps, OFDM
 Uplink
 Peak 75 Mbps, SC-FDMA
 Low latency – 5 ms for small packets
 MIMO
 Support for cell sizes from 10s of meters radius (femto &
picocells) up to 100 km radius macrocells
28

29. LTE Deployments
29
Source: 4G Americas

30. LTE Architecture
 E-UTRAN - evolved UMTS
Terrestrial Radio Access
 Manage end nodes, handover,
& interference mitigation
 EPC – Evolved Packet Core
 Higher data rates, low-latency,
support for multiple radio
access
30
Source: www.wirelessweek.com/articles/2010/10/part-2-mobile-network-evolution-and-lte-architecture

31. LTE Advanced
 Major enhancements to LTE
 Comply with IMT-Advanced standard
 First deployed in October 2012 in Russia
 Increased spectrum flexibility
 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, & 20 MHz
wide cells
31

32. LTE Vs. LTE-Advanced
32
Source: http://wwwen.zte.com.cn/endata/magazine/ztetechnologies/2009year/no8/articles/201001/t20100119_179662.html

33. Comparison
33
Source: http://www.unwiredinsight.com/2010/lte-performance

34. Mobile Security
34
Source: Wireless security in LTE networks by Monica Paolini, Senza Fili Consulting

35. Mobile Security (Cont.)
 3G
 Much better than 2G
 Encrypted communication between mobile station,
base station controller, & mobile switching centre
 Mobile station to authenticate the network it is
attaching to – no impersonators
35
RNC - Radio Network Controller

36. Mobile Security (Cont.)
 4G
 LTE – should support entire IPSec architecture
 Current deployments may not fully support IPSec
36