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1. An Overview
‘Digital Cellular Network
Technologies’
Presented by
Prof. T. L. Singal
National-Level Faculty Development Workshop
“Challenges for Research in Wireless Communication Technologies”
May 21-23, 2012
Chitkara University, Punjab
1

2. Evolution of Cellular
Generations – A Recap
2

3. Cellular Network Generations
• 1G: First Generation Analog Cellular System
- Analog voice
• 2G: First Digital Cellular System
- Digital voice and messaging
• 2.5 G: Digital Cellular System
- Increase in digital data rates
• 3G: Digital Cellular System with increase in
functionality - Broadband data and Voice over IP
• 4G: Future re-architecting of digital cellular
infrastructure - Increased data throughput 3

4. Examples of 1G and 2G
• First Generation Cellular Networks (1G)
– Analog systems based on FDMA (e.g. AMPS, NMT,
UK-TACS)
• Second Generation Cellular Networks (2G)
– Digital systems based on TDMA and CDMA (e.g.
GSM, TIA/EIA-136, IS-95)
• Second Generation+ Cellular Networks (2.5G)
– Digital systems based on TDMA and CDMA with
higher data rate capabilities (e.g. GPRS, cdma2000)
4

5. Advantages/Disadvantages -
1G and 2G Networks
• First Generation Cellular Networks (1G)
– Spotty coverage
• Second Generation Wireless (2G)
– Improved voice quality
– Limited low-speed, circuit-switched data capabilities
• Second Generation Wireless + (2.5G)
– Introduction of packet data
– Higher data rates (up to 144 kbps) 5

6. 3G and 4G
• Third Generation Cellular Networks (3G)
– Digital systems based on TDMA (GSM) and CDMA
with data rate capability upto 2 Mbps (e.g.
WCDMA/UMTS, cdma2000, UWC-136)
• Fourth Generation Cellular Networks (4G)
– Digital systems based on OFDMA and MC-CDMA
with higher data rate capability for advanced
multimedia applications.
6

7. Evolution of Cellular Networks
Fourth Generation
7

8. Key Parameters
8

9. Paradigm shift - 1G towards 4G
Fourth Generation
9

10. Comparison of 1G to 4G Systems
Generation 1G 2G 3G 4G
OFDMA,
MC-CDMA
10

11. GSM and CDMA
11

12. Multiple Access
Technologies
12

13. GSM - FDMA and TDMA
Time
7
6
Amplitude
5
4 time slot number
3
2
1
0 Frequency
1 2 3 4 5 6
ARFCN
13

14. Structure of a GSM Signal
GSM carriers are spaced 200
KHz apart.
In the BTS downlink signal,
different timeslots belong to
different users - a mobile
listens only to its recurring
timeslots.
The mobile on its uplink
transmits only during its
assigned timeslots. 14

15. GSM Network Areas
PLMN service area
MSC/VLR
service areas
Location
Areas
Cells
15

16. GSM Cell Plan
16

17. GSM Network Architecture
NMC
BTS
OMC OMC
BTS BSC
BTS
M VLR
BSS
MSC
S MSC EIR
BTS
AuC
BTS BSC VLR
MS MSC
BTS MSC HLR
BSS
Interface to other
networks
17

18. A Typical GSM System
18

19. Advantages/Disadvantages
- GSM Network
• Advantages
– Can provide roaming services
– Reduces probability of total corruption of speech
– Offers standard protocols between components
• Disadvantages
– Limited data rate capability
– Macrocells affected by multipath signal loss
– Low Capacity
19

20. GSM Networks Future Trends
WCDMA
<470 kbps
Evolution
384 - 2048 kbps
EDGE
EGPRS
GPRS
WCDMA
HSCSD 9 - 53.6 kbps Phase I
144 - 384 kbps
GSM 9.6 - 28.8 kbps
Data
9.6 kbps
1999 2000 2001 2002 2003-2005
20

21. What is CDMA?
Code Division Multiple Access
CDMA is a spread spectrum system and is directly related to
the number of users accessing the system.
CDMA system allow one-cell frequency reuse and all users
use the entire carrier, all the time. Each user is distinguished
by a Direct Sequence Code during a call.
21

22. CDMA: Using A New Dimension
22

23. CDMA is a Spread- Spectrum System
23

24. CDMA Cell Plan
1
1 1
1 1 1
1 1
1
24

25. CDMA Network Architecture
BTS
OS
BTS BSC
BTS
MS VLR
BS
MSC
MSC EIR
BTS
AuC
BTS BSC VLR
MS MSC
BTS MSC HLR
BS Interface to other
networks
25

26. CDMA - Advantages
• Easy frequency planning (Frequency reuse of one)
• Greater coverage with fewer cells
• High capacity without hard blocking limits
• Excellent call quality (supports soft handoff)
• Inherent privacy due to unique user codes
• Lower power transmission
• Longer battery life
• Tight power control
• Technology platform extendable to new services
• Providing reliable transport mechanism for data
communications, such as facsimile and internet traffic
26

27. CDMA - Advantages contd…
 Dramatically improving the telephone traffic capacity.
 Significantly improving the voice quality and eliminating
the audible effects of multipath fading.
 Reducing the incidence of dropped calls due to handoff
failures.
 Reducing the number of sites needed to support any
given amount of traffic.
 Simplifying site selection, thus reducing deployment and
operating costs because fewer cell sites are needed.
 Reducing average transmitted power, thereby reducing
interference. 27

28. Capacity Comparisons
– GSM and CDMA
GSM Capacity limit is fixed CDMA Capacity limit is
at 8 x number of ARFCNs „soft‟, Increases with
per cell decrease in quality.
Typically 4-5 times that of
a GSM system. 28

29. GSM
Architecture
29

30. 30

31. 31

32. 2G+ Cellular Network
32

33. 3G Market Drivers
33

34. How Do Operators Get to 3G?
34

35. 3G air interface technologies
WCDMA/UMTS cdma2000 UWC-136
CDMA-based CDMA-based TDMA-based
Direct sequence Multi-carrier --
Evolution of GSM Evolution of Evolution of
IS-95 TDMA
Requires new Could be Could be
spectrum deployed in deployed in
existing spectrum existing spectrum
35

36. GPRS Architecture
36

37. Example for packet
routing in GPRS
37

38. Example of GPRS Internet
Connection
38

39. The GSM Technology Path to 3G
39

40. 3 Steps to 3G:
The GSM Network Transition
40

41. Global TDMA Convergence
Mobility Gateway
ANSI-136 GSM
Network Network
TCP/IP
Network
IW ANSI-41 IW MAP
ANSI-136 EGPRS GSM
UWC-136/EDGE

42. The CDMA Technology Path to 3G
42

43. 3G Network Architecture
43

44. Advantages – The 3G Network
• Common worldwide spectrum
• Global seamless roaming
• Multimedia services on the mobile internet
• Flexible, spectrum-efficient network
• Enhanced security and performance
• Wireline services and quality levels
• Rapid introduction of new technology
44

45. Disadvantages – The 3G Network
• Insufficient bandwidth
• Service differentiation
• IP translators are the wrong application and
service model (e.g., WAP, imode, etc.)
• Wrong architectural model for IP data
45

46. KEY APPLICATIONS
• Current: ~10 kb/s, circuit/packet
– Fax
– Short-messaging
– Being evolved to ~50-100 kb/s peak rate
• Needed to make wireless data attractive:
– Web Browsing - downlink bandwidth hungry
– FTP or Emails with file attachment - both links
• 3G: “Multimedia,” mainly packet
– Wide-area, low mobility, 384 kb/s
– Wide-area, high mobility, 144 kb/s
– Indoor, 2 Mb/s
• Beyond 3G ?

47. Radio Technology Evolution
• High Speed Services
– Nominal Rates:
• At least 144 kbps macrocell
• At least 384 kbps outdoor pedestrian
• At least 2 Mbps indoor
• => 1-2 Mbps or higher in macrocell
– Support emerging IP-based services
• Real-time and non real-time
– Optimized for packet-switched operation
• Support appropriate QoS definitions
• Data and multimedia services

48. Technology Evolution to IMT-
2000 Radio Access
Existing New
EDGE/GPRS SpectrumSpectrum
IMT-2000
GSM GSM+ Systems
GPRS
UMTS/
PDC W-CDMA
TDMA TDMA UWC-136 HS
(EDGE) ?
(IS-136) IS-136+
?
CDMA CDMA 3G-1X cdma2000
(IS-95)

49. Deployment Scenario
Edge
SGSN
WCDMA GPRS
backbone
SGSN GGSN
BG
BG GGSN
GPRS Inter-
backbone operator
GGSN GPRS
SGSN
GGSN
Edge
router Public
Internet router server
router Backbone

50. Wireless Data Terminals
Nokia
Sierra PCMCIA Nokia 9110 The new 3G vision
CDPD Modem
Ericsson R380
phone, which
features wireless
data functions

51. Looking to the
Future….
4G and Beyond
51

52. 52

53. Transition from 3G to 4G ….
53

54. Positions and Challenges for 4G
• Wireless Data is king
– Direction: design for data and IP - not voice circuits
• Wide variety of wireless link technologies; 2G/3G,
wireless LAN, MANETs, PANs, wireless sensor networks;
new radio 4G technologies will emerge
– Direction: IP over every radio link
• Multitude of mobile devices; sensors, watches, pagers,
pocket PCs, etc.
– Direction: IP on every mobile device
54

55. Key Elements of 4G Vision
55

56. • Fully converged services
Personal communications, information systems, broadcast,
entertainment and a wider range of services available conveniently,
securely and in a manner reflecting the user’s personal preferences.
• Ubiquitous mobile access
The dominant mode of access will be mobile, accounting for fully
converged services, including mobile access to commercial and
retail services.
• Diverse user devices
The user will be served by a wide variety of low-cost mobile devices
to access content conveniently and seamlessly. Devices will interact
with users in a multi-sensory manner.
56

57. • Autonomous networks
4G systems will be highly autonomous adaptive networks capable of
self-management of their structure to meet users’ changing and
evolving demands, for both services and capacity. Efficient and cost-
effective use of the radio spectrum will be an essential element of their
operation.
• Software dependency
Intelligent Mobile Agents will exist throughout the networks and in
user devices, acting continually to simplify tasks and ensure
transparency to the user. These Mobile Agents will act at all levels,
from managing an individual user’s content preferences, to organizing
and reconfiguring major elements of networks.
57

58. Advantages - The 4G Network
• Improved Spectral Efficiency
• Improved quality of service
• Increased data throughput
• Broadcast and Cellular Network Convergence
• Adaptive and Reconfigurable Systems
• Advanced Antenna Technologies
• Creation of new business models for operators
58

59. 4G Network Architecture
59

60. 4G Network Scenario
60

61. 4G Network Connectivity
61

62. Vision of Beyond 4G
62

63. Evolution from voice-only to
multimedia mobile services
63

64. Ultimate Goal – Maximum Data Rate
64

65. T. L. Singal graduated from National Institute of
Technology, Kurukshetra in 1981 . He began his
illustrious career with Avionics Design Bureau at
HAL, Hyderabad and worked on design and
development of Air-Route Surveillance Radar
Communication System. Then he led R&D group in
a Telecom company and successfully developed
Multi-Access Wireless Communication Systems.
He executed international assignment as Senior Network Consultant
with Flextronics International Inc. USA during 2000-02. He was
associated with Nokia, AT&T, Cingular Wireless and Nortel
Networks, for optimization of 2G/3G Cellular Networks in USA.
Since 2003, he is in teaching profession in engineering colleges in
India. He has number of technical research papers published in
the IEEE Proceedings, Journals, and International/National
Conferences. He has authored two text-books `Wireless
Communications’ and `Analog & Digital Communications’,
published by renowned publisher Tata McGraw-Hill. 65

66. References
T L Singal, Wireless Communications,
ISBN: 978-0-07-068178-1,
Tata McGraw-Hill, First Edition, 2010.
www.mhhe.com/singal/wc
66

67. Queries?
tl.singal@chitkara.edu.in
Contact No: +91-98145-42041 67

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