1. Cellular Networks
Lecture 6
Paul Flynn

2. Cellular Telephony - Architecture

3. Very Basic Cellular/PCS Architecture
Mobility
Database
Public Switched
Telephone Network
Base Station
Controller
Mobile
Switching
Center
(MSC)
Radio Network
Base Station
(BS)
Mobile Station

4. Duplex Communication - FDD
FDD: Frequency Division Duplex
Base Station B
Mobile Terminal M
Forward Channel
Reverse Channel
Forward Channel and Reverse Channel use different frequency
bands

5. Access Methods FDMA TDMA CDMA Frequency Frequency Time Time Frequency

6. Clusters A cluster is a group of cells
No channels are reused within a cluster
A seven Cell Cluster

7. Example - Frequency Spectrum Allocation in U.S. Cellular Radio Service
Reverse Channel
Forward Channel
991
992 …
1023 1 2 …
799
991
992 …
1023 1 2 …
799
MHz
MHz
Channel Number
Center Frequency (MHz)
Reverse Channel 1 <=N <= 799
991 <= N <= 1023
0.030N
0.030(N-1023)
Forward Channel 1 <=N <= 799
991 <= N <= 1023
0.030N
0.030(N-1023)
(Channels are unused)
Channel bandwidth is 45 MHz

8. Frequency Reuse
Only a small number of radio channel frequencies were available for mobile systems
Therefore engineers had to find a way to reuse radio channels to carry more than one conversation at a time
The solution the industry adopted was called frequency reuse. Implemented by restructuring the mobile telephone system architecture into the cellular concept

9. Frequency Reuse
The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area
Cells are assigned a group of channels that is completely different from neighbouring cells
The coverage area of cells is called the footprint and is limited by a boundary so that the same group of channels can be used in cells that are far enough apart

10. Frequency Reuse
Cells with the same number have the same set of frequencies
Frequency Reuse

11. Frequency Reuse using 7 frequencies allocations
Each cell is generally 4 to 8 miles in diameter with a lower limit
around 2 miles.

12. Cell Splitting
Allows urban centres to be split into as many areas as necessary for acceptable service levels in heavy-traffic regions, while larger, less expensive cells can be used to cover remote rural regions

13. Cellular Concept with Sectors
frequency re-use
base station

14. Hand-off
The final obstacle in the development of the cellular network involved the problem created when a mobile subscriber moved from one cell to another during a call

15. GSM infrastructure MSC, BSC, BTS, VLR, HLR, GSGN, GSSN

16. Compared to a fixed network
Gateway MSC
Transit exchang
Local switches
MSC
BSC
Subscriber stage
Fixed phone MS

17. What’s new? Radio access network Encryption Voice coding
Locate a mobile station
Identify and authenticate
Handle mobility during a call

18. A bird eye’s view GMSC Access Network MSC databases BTS BSC BSC BSC

19. ”Typical” Mobile operator
One to ten MSC per 1 M subscribers
Ten to one hundred BSC per MSC
Thousands of BTS per 1 M subscribers

20. Base Transceiver Station
Controls the radio link
encryption
error control
signal strength
1 - 6 duplex carriers, for example:
two layers
120o sectors
(6+8)*3 = 42 voice calls
Cost ~ 100 – 200 k$

21. Base Station Controller
communication with the mobile terminal
local hand-over
voice codecs
carrier allocation
paging to terminals
talks to the MSC
serves up to 40 BTSs
could be co-located with MSC

22. Mobile Switching Centre
Mobility management
identifies and authenticates
locates
switches between BSCs
Handover to other MSCs
64 kbps regular voice channels

23. Radio Access network A carrier is divided into logical channels
control channels CCH
traffic channels TCH
The first carrier holds 2 controll channels and 6 traffic channels. Additional carriers holds only traffic channels.

24. Control Channels Broadcast Common control Dedicated control
Frequency correction: to synchronize (FCCH)
Broadcast control: this is me, these are my neighbours (BCCH)
Common control
Paging: to notify a mobile station (PCH)
Random access: for the mobile to request service (RACH)
Access grant: reply with assigned dedicated control channel (AGCH)
Dedicated control
Standalone dedicated control: used during call set-up, SMS etc (SDCCH)
Slow associated control: power, time etc (SACCH)
Fast associated control: handover etc, uses the TCH (FACCH)
Cell broadcast: cell broadcast

25. Traffic Channels Duplex Error control Full rate (TCH/F)
Forward Error Correction (FEC)
retransmission (ARQ)
Full rate (TCH/F)
13 Kbps speech
9,6 or 14,4 Kpbs data
Half rate (TCH/H)
6,5 Kbps speech
7,2 or 4,8 Kbps data

26. Logical channels Hyperframe: 2048 superframes 3h28m
Superframe: 26 or 51 multiframes 6.12 s
CCH
CCH
Multiframe: 26 or 51 TDMA frames
CCH
TCH
8 time-slot TDMA frame ms

27. One TDMA frame Normal burst Frequency correction burst
148 b ms
tail
guard
8.25
tail
training
Normal burst 3
57 b
26 b
57 b 3
user data
user data
stealing flags
Frequency correction burst
Synchronization burst
Dummy burst
Access burst

28. Keeping track of a mobile station
VLR visiting location register
Location area
Location area
update the VLR with new location area

29. Moving to a new MSC VLR which LA which MSC ? Location area
update the VLR with new location area and new MSC

30. but also…. HLR home location register VLR
update the home location register!

31. Home Location Register
incomming call
PSTN
where is the mobile?
GMSC
HLR
MSC
How do we reach him?
VLR

32. Mobile station numbers
mobile subscriber ISDN number (MSISDN) i.e. the phone number
PSTN
GMSC
HLR
Mobile Station Roaming Number (MSRN).
MSC
VLR
Temporary Mobile Subscriber Identity
International Mobile Subscriber Identity

33. GPRS Internet Gateway GPRS Support Node GGSN Packet Control Unit
Access Network
Packet Control Unit
BTS
BSC
UDP/TCP tunnel
Serving GPRS Support Node SGSN
BTS MS
BTS

34. Looking to PCS from different Angles
Internet
PSTN
(Telephone Network)
Wireless Access
Mobile Users
Laptop users
Pocket PC users
Mobile IP, DHCP enabled computers
Mobile Users
Cell phone users
Cordless phone users
Telecom People View
Data Networking People View

35. Telecom and Data Networking
Telecom Interest
Data Networking Interest
- Voice Transmission
- Frequency Reuse
Handoff Management
Location Tracking
Roaming
QoS
GSM, CDMA, Cordless Phones,
GPRS, EDGE
Data Transmission
Mobile IP (integrating mobile hosts to internet)
Ad-hoc Networks
TCP over Wireless
Service Discovery
Radio Propagation
Link Characteristics
Error Models
-Wireless Medium
Access (MAC)
- Error Control

36. Major Mobile Radio Standards - Europe
Type
Year
Intro
Multiple Access
Frequency Band
(MHz)
Modulation
Channel BW
(KHz)
ETACS
Cellular
1985
FDMA
900 FM 25
NMT-900
1986
12.5
GSM
Cellular/PCS
1990
TDMA
GMSK
200KHz
C-450
20-10
ERMES
Paging
1993
FDMA4
Several
4-FSK
CT2
Cordless
1989
GFSK
100
DECT
1728
DCS-1800
Cordless/PCS
200

37. Example - Frequency Spectrum Allocation in U.S. Cellular Radio Service
Reverse Channel
Forward Channel
991
992 …
1023 1 2 …
799
991
992 …
1023 1 2 …
799
MHz
MHz
Channel Number
Center Frequency (MHz)
Reverse Channel 1 <=N <= 799
991 <= N <= 1023
0.030N
0.030(N-1023)
Forward Channel 1 <=N <= 799
991 <= N <= 1023
0.030N
0.030(N-1023)
(Channels are unused)
Channel bandwidth is 45 MHz

38. 2G Technologies cdmaOne (IS-95) GSM, DCS-1900 IS-54/IS-136 PDC
Uplink Frequencies (MHz)
(Cellular)
(US PCS)
MHz (Eurpe) (US PCS)
800 MHz, 1500 Mhz (Japan)
Downlink Frequencies
MHz (US Cellular) MHz (US PCS)
(Europa)
(US PCS)
MHz (Cellular) (US PCS)
800 MHz, 1500 MHz (Japan)
Deplexing
FDD
Multiple Access
CDMA
TDMA
Modulation
BPSK with Quadrature Spreading
GMSK with BT=0.3
p/4 DQPSK
Carrier Seperation
1.25 MHz
200 KHz
30 KHz (IS-136) (25 KHz PDC)
Channel Data Rate
Mchips/sec
Kbps
48.6 Kbps (IS-136) 42 Kbps (PDC)
Voice Channels per carrier 64 8 3
Speech Coding
CELP at 13Kbps EVRC at 8Kbps
RPE-LTP at 13 Kbps
VSELP at 7.95 Kbps

39. GSM Speech Signal Processing

41. GSM and CDMA Coverage Map Worldwide

42. Evolution

43. 1G TECHNOLOGY
1G refers to the first generation of wireless telephone technology, mobile telecommunications which was first introduced in 1980s and completed in early 1990s.
It's Speed was upto 2.4kbps.
It allows the voice calls in 1 country.
1G network use Analog Signal.
AMPS was first launched in USA in 1G mobile
systems. 43 43

44. Poor Handoff Reliability
DRAWBACKS OF 1G
Poor Voice Quality
Poor Battery Life
Large Phone Size
No Security
Limited Capacity
Poor Handoff Reliability
1G Wireless System 44 44

45. 2G TECHNOLOGY
2G technology refers to the 2nd generation which is based on GSM.
It was launched in Finland in the year 1991.
2G network use digital signals.
It’s data speed was upto 64kbps.
Features Includes:
It enables services such as text messages,
picture messages and MMS (multi media message).
It provides better quality and capacity . 45

46. 2G requires strong digital signals
DRAWBACKS OF 2G
2G requires strong digital signals
to help mobile phones work. If there
is no network coverage in any specific
area , digital signals would weak.
These systems are unable to
handle complex data such as Videos.
2G Wireless System 46 46

47. 3G TECHNOLOGY
3G technology refer to third generation which was introduced in year 2000s.
Data Transmission speed increased from
144kbps- 2Mbps.
Typically called Smart Phones and
features increased its bandwidth
and data transfer rates to accommodate
web-based applications and audio
and video files. 47

48. FEATURES OF 3G TECHNOLOGY
Providing Faster Communication
Send/Receive Large Messages
High Speed Web / More Security
Video Conferencing / 3D Gaming
TV Streaming/ Mobile TV/ Phone Calls
Large Capacities and Broadband Capabilities
11 sec – 1.5 min. time to download a 3 min Mp3 song. 48

49. DRAWBACKS OF 3G TECHNOLOGY
Expensive fees for 3G Licenses Services
It was challenge to build the infrastructure
for 3G
High Bandwidth Requirement
Expensive 3G Phones.
Large Cell Phones 49

50. 4G TECHNOLOGY (Anytime ,Anywhere)50

51. 4G TECHNOLOGY (Anytime ,Anywhere)
4G technology refer to or short name of fourth Generation which was started from late 2000s.
Capable of providing 100Mbps – 1Gbps speed.
One of the basic term used to describe 4G is MAGIC.
MAGIC:
Mobile Multimedia
Anytime Anywhere
Global Mobility Support
Integrated Wireless Solution
Customized Personal Services
Also known as Mobile Broadband Everywhere. 51

52. Countries Have 4-G
Except for the Scandinavian Countries (Northern Europe that includes Denmark and two of the nations of Scandinavian , Norway and Sweden. ), a few countries have started the 4G commercially. In the US, Sprint Nextel and Others Germany , Spain, China , Japan and England are also using the 4G services and mobiles . 52

53. WIRLESS MODELS OF 3G & 4G
3G WIRELESS SYSTEM
4G WIRELESS SYSTEM 53 53

54. 5G TECHNOLOGY
5G technology refer to short name of fifth Generation which was started from late 2010s.
Complete wireless communication
with almost no limitations.
It is highly supportable to WWWW
(Wireless World Wide Web). 54

55. BENEFITS OF 5G TECHNOLOGY
High Speed, High Capacity
5G technology providing large broadcasting of data in Gbps .
Multi - Media Newspapers, watch T.V programs with the clarity
as to that of an HD Quality.
Faster data transmission that of the
previous generations.
Large Phone Memory, Dialing Speed,
clarity in Audio/Video.
Support interactive multimedia , voice,
streaming video, Internet and other
5G is More Effective and More Attractive. 55

56. EVOLUTION OF 1G TO 5G TECHNOLOGY56

57. WIRELESS APPLICATIONS
Wireless applications are those
which we use free space as the
transmission medium & do not
involve cabling like fibre or
copper cables. 57

58. Wireless solution for: Business and Industry Schools , Colleges
WIRELESS SERVICES
Wireless solution for:
Business and Industry
Schools , Colleges
Doctors , Pilots
Police and Vehicles etc. 58

59. CONCLUSION
All totally the best way to help all users is to use 5G as the next wireless system and in totally it is safety and secure for public, this the need that demands the solution.
Today’s wired society is going wireless and if it has problem, 5G is answer.
5G technology is going to give tough competition to Computers and Laptops.
It will be available in the market at affordable cost with more reliability than previous mobiles. 59 59