cellular concept

1. Cellular Networks

2. LOGO INTRODUCTION
WHAT IS WIRELESS ?
The word wireless is dictionary defined “having no wires ”
.
connected by radio waves and or microwaves to maintain
communications.
copper or optical fibre
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3. Multiple Access Techniques: How to allocate users
Time
Frequency
Session1
Session2
Session3
Session4
Frequency Division
Multiple Access (FDMA)
1G Cellular (AMPS)
Time
Frequency
Time Division
Multiple Access (TDMA)
2G TDMA
3G TDMA
Session2
Session3
Session1
Session4
Time
Frequency
Code Division
Multiple Access (CDMA)
All sessions
based on a
code
2G CDMA (IS-95)
3G CDMA

4. A Cellular Network
Public
Switched
Telephone
Network
(PSTN)
Mobile
Telephone
Switching
Center
(MTSC)
Base Transceiver Station (BTS)
Mobile User
Cell 1
Cell 2
Cordless connection
Wired connection
HLR VLR
HLR = Home Location Register
VLR = Visitor Location Register

5. 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

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

7. Frequency Reuse using 7
frequencies allocations
f4
f3
f2
f1
f6
f7
f5 f4
f3
f2
f1
f6
f7
f5
f4
f3
f2
f1
f6
f7
f5
f4
f3
f2
f1
f6
f7
f5
f4
f3
f2
f1
f6
f7
f5
Each cell is generally 4 to 8 miles in diameter with a lower limit
around 2 miles.

9. Problem with Smaller Clustersize
Interfering cells are closer by when clustersize is smaller.

12. 0G Wireless
• Mobile radio telephones were used for military
communications in early 20th century
• Car-based telephones first introduced in mid 1940s
– Single large transmitter on top of a tall building
– Single channel used for sending and receiving
– To talk, user pushed a button, enabled transmission and disabled
reception
– Became known as “push-to-talk” in 1950s
– CB-radio, taxis, police cars use this technology
• IMTS (Improved Mobile Telephone System) introduced in
1960s
– Used two channels (one for sending, one for receiving)
– No need for push-to-talk
– Used 23 channels from 150 MHz to 450 MHz

13. First-Generation Cellular
• Advanced Mobile Phone Service (AMPS) invented at Bell Labs
and first installed in 1982
• Used in England (called TACS) and Japan (called MCS-L1)
• Key ideas:
– Exclusively analog
– Geographical area divided into cells (typically 10-25km)
– Cells are small: Frequency reuse exploited in nearby (not adjacent) cells
– As compared to IMTS, could use 5 to 10 times more users in same area by
using frequency re-use (divide area into cells)
– Smaller cells also required less powerful, cheaper,smaller devices

15. Second Generation Cellular
• Based on digital transmission
• Different approaches in US and Europe
• US: divergence
– Only one player (AMPS) in 1G
– Became several players in 2G due to competition
– Survivors
• IS-54 and IS-135: backward compatible with AMPS frequency
allocation (dual mode - analog and digital)
• IS-95: uses spread spectrum
• Europe: Convergence
– 5 incompatible 1G systems (no clear winner)
– European PTT development of GSM (uses new
frequency and completely digital communication)

17. Differences Between First and
Second Generation Systems
• Digital traffic channels – first-generation systems
are almost purely analog; second-generation
systems are digital
• Encryption – all second generation systems
provide encryption to prevent eavesdropping
• Error detection and correction – second-generation
digital traffic allows for detection and correction,
giving clear voice reception
• Channel access – second-generation systems allow
channels to be dynamically shared by a number of
users

18. Integrating Data Over Cellular
• Direct access to digital channel
• Voice and data using one handset
• PCS 1900 (GSM-1900)
– 9.6 kbps circuit switched data
– 14.4 kbps under definition
– Packet mode specified
– Short message service
• IS-95-based CDMA
– 13 kbps circuit switched data
– Packet mode specified
– Short message service

19. GSM (Global System for Mobile Communications)
• Completely designed from scratch (no backward
compatability)
• Uses 124 channels per cell, each channel can
support 8 users through TDM (992 users max)
• Some channels used for control signals, etc
• Several flavors based on frequency:
– GSM (900 MHz)
– GSM 1800 (called DCS 1800)
– GSM 1900 (called DCS 1900) - used in North America
• GSM 1900 phone only works in North America.
• In Europe, you can transfer your SIM (Subscriber
Identity Module) card to a phone of the correct
frequency. This is called SIM-roaming.

23. 2G CDMA Cellular
IS-95 is the best known example of 2G with
CDMA
Advantages of CDMA for Cellular
• Frequency diversity – frequency-dependent
transmission impairments have less effect on
signal
• Multipath resistance – chipping codes used for
CDMA exhibit low cross correlation and low
autocorrelation
• Privacy – privacy is inherent since spread
spectrum is obtained by use of noise-like signals
• Graceful degradation – system only gradually
degrades as more users access the system

24. Drawbacks of CDMA Cellular
• Self-jamming – arriving transmissions from
multiple users not aligned on chip boundaries
unless users are perfectly synchronized
• Near-far problem – signals closer to the receiver
are received with less attenuation than signals
farther away
• Soft handoff – requires that the mobile acquires
the new cell before it relinquishes the old; this is
more complex than hard handoff used in FDMA
and TDMA schemes

25. LOGO 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.
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26. LOGO
DRAWBACKS OF
1G
Poor Voice Quality Poor Battery Life Large
Phone Size No Security Limited Capacity
Poor Handoff Reliability
1G Wireless System
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27. LOGO
2G
TECHNOL
OGY
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 .
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28. LOGO
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
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29. LOGO WIRELESS MODELS OF 1G & 2G
1G WIRELESS SYSTEMS 2G WIRELESS SYSTEMS
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30. LOGO
2.5G
TECHNOL
OGY
2.5G is a technology between the second (2G) and
third (3G) generation of mobile telephony.
2.5G is sometimes described as 2G Cellular
Technology combined with GPRS.
Features Includes:
Phone Calls
Send/Receive E-mail Messages
Web Browsing
Speed : 64-144 kbps
Camera Phones
Take a time of 6-9 mins. to download a 3 mins. Mp3
song
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31. LOGO
3G
TECHNOL
OGY
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.
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32. LOGO
FEATURES OF 3G
TECHNOLOGY
Providing Faster Communication
Send/Receive Large Email 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.
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33. LOGO
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
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34. LOGO
4G TECHNOLOGY
(Anytime ,Anywhere)
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35. LOGO
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.
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36. LOGO 4G (Anytime, Anywhere)
The next generations of wireless technology that promises
higher data rates and expanded multimedia services.
Capable to provide speed 100Mbps-1Gbps. High QOS and High
Security
Provide any kind of service at any time as per user
requirements, anywhere.
Features Include:
More Security
High Speed
High Capacity
Low Cost Per-bit etc.
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37. LOGO DRAWBACKS OF 4G
Battery uses is more
Hard to implement
Need complicated hardware
Expensive equipment
required
to implement next generation
network.
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38. LOGO COMPARISON BETWEEN 3G Vs 4G
Technology 3G 4G
Data Transfer Rate 3.1 MB/sec 100 MB/sec
Internet Services Broadband Ultra Broadband
Mobile - TV Resolution Low High
Bandwidth 5-20 MHz 100MHz
Frequency 1.6-2 GHz 2-8 GHz
Download and upload 5.8 Mbps 14 Mbps
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The basic difference between 3G and 4G is in data transfer and signal
quality.

39. LOGO
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 .
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40. LOGO
3G WIRELESS SYSTEM 4G WIRELESS SYSTEM
WIRLESS MODELS OF 3G & 4G
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41. LOGO TECHNOLO
GY
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).
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42. LOGO
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.
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43. LOGO
COMPARISON
BETWEEN 4G Vs 5G
The following basic differences between 4G and 5G are:
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44. LOGO
EVOLUTION OF 1G TO 5G TECHNOLOGY
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45. What is WiMax?
• Worldwide Interoperability for
Microwave Access
• Last mile wireless broadband access
• Alternative to cable and DSL
• Deliver data, voice, video
• Support hundreds to thousands of
homes/business

46. • Defined by IEEE as 802.16
• Typical target environment:
• Targets fixed, portable, and mobile stations
• Environments with and without line of sight
• Cell radius of 3-10 kilometers
• Capacities of up to 40 Mbps per channel
• Mobile network deployments of up to 15
Mbps, 3 km radius

47. Builds on and
Extends WiFi Technology
• Advantages of WiFi are:
• Easy to deploy, unlicensed spectrum, low
cost
• Supports (limited) mobility
• But WiMax needs to address the
following:

48. WiFi limitations
• Susceptible to interference
• 802.11 targets short-range indoor
operation (mostly)
• Security is a concern
• Limited level of mobility
• WiMax is intended to complement WiFi
• WiMax Forum: promotes WiMax and
looks after interoperability

49. WiMax Deployment