about cellular networks

1. Chapter-2
Cellular Communication system
1

2. Outline
• Introduction to wireless communication
• Wireless Impact
• Cellular telephone
• Cellular Concept
• Principles of Cellular Networks
• Fading
• Cellular network generations
• 1G
• 2G
• 3G
• 4G
• 5G
2

3. Introduction to wireless communication
• Wireless Communication is the fastest growing and most vibrant
technological areas in the communication field. Wireless
Communication is a method of transmitting information from one
point to other, without using any connection like wires, cables or any
physical medium.
• Generally, in a communication system, information is transmitted from
transmitter to receiver that are placed over a limited distance. With the
help of Wireless Communication, the transmitter and receiver can be
placed anywhere between few meters (like a T.V. Remote Control) to
thousand kilometers (Satellite Communication).
• We live in a World of communication and Wireless Communication, in
particular, is a key part of our lives. Some of the commonly used
Wireless Communication Systems in our day – to – day life are:
Mobile Phones, GPS Receivers, Remote Controls, Bluetooth Audio
and Wi-Fi etc. 3

4. Introduction cont.
• Wireless communication is realized due to electromagnetic wave. An
Electromagnetic Wave consists of both electric and magnetic fields in the
form of time varying sinusoidal waves. Both these fields are oscillating
perpendicular to each other and to the direction of propagation of the
Electromagnetic Wave.
4

5. Wireless Impact
• Profound impact on the working habit and the
economy
• Shrinks the world
• Always on
• Always connected
• Changes the way of people communication
• Social networking
• Converged global wireless network
Introduction 1-5

6. Cellular telephone
•Started as a replacement to the wired telephone
•Early generations offered voice and limited data
•Third and fourth generation systems provides
• Voice
• Texting
• Social networking
• Mobile apps
• Mobile Web
• Mobile commerce
• Video streaming
6

7. Cellular Network
• What is a Cell?
7

8. Cellular Network, cont.
• Proposed by Bell Labs 1971
Geographic Service divided into
smaller “cells”
• Neighboring cells do not use same set
of frequencies to prevent interference
• Often approximate coverage area of a
cell by an idealized hexagon
• Increase system capacity by frequency
reuse.
• Propagation models represent cell as a
circular area
• Approximate cell coverage with a
hexagon - allows easier analysis
• Frequency assignment of F MHz
for the system
• The multiple access techniques
translates F to T traffic channels
• Cluster of cells K = group of
adjacent cells which use all of the
systems frequency assignment
8

9. Cont..
• Why not a large radio tower and large
service area?
• Number of simultaneous users would be very
limited (to total number of traffic channels T)
• Mobile handset would have greater power
requirement
• Cellular concept - small cells with frequency
reuse
• Advantages
• lower power handsets
• Increases system capacity with frequency reuse
• Drawbacks:
• Cost of cells (BTs)
• Frequent handoffs between cells
• Need to track user to route incoming
call/message
9

10. Basic Components of a Cellular Telephone System
10

11. Cont.
11

12. Cont.
• Cellular Mobile Phone:
• is a portable telephone that can make and receive calls over a radio
frequency link while the user is moving within a telephone service area.
• Base Station:
• A Low Power Transmitter, other Radio Equipment [Transceivers] plus a small
Tower
• Mobile Switching Center [MSC] /Mobile Telephone Switching
Office[MTSO]
• An Interface between Base Stations and the PSTN Controls all the Base
Stations in the Region and Processes User ID and other Call Parameters
• A typical MSC can handle up to 100,000 Mobiles, and 5000 Simultaneous
calls
• Handles Handoff Requests, Call Initiation Requests, and all Billing & System
Maintenance Functions 12

13. Principles of Cellular Networks
• Underlying technology for mobile phones, personal communication systems,
wireless networking etc.
• Developed for mobile radio telephone
• Replaces high power transmitter/receiver systems
• Use lower power, shorter range, more transmitters
• Cellular Network Organization
• Multiple low power transmitters
• 100w or less
• Area divided into cells
• Each with own antenna
• Each with own range of frequencies
• Served by base station
• Transmitter, receiver, control unit
• Adjacent cells on different frequencies to avoid crosstalk
13

14. Shape of Cells
• Square
• Width d cell has four neighbours at distance d and four at distance d
• Better if all adjacent antennas equidistant
• Simplifies choosing and switching to new antenna
• Hexagon
• Provides equidistant antennas
• Radius defined as radius of circumcircle
• Distance from centre to vertex equals length of side
• Distance between centres of cells radius R is R
• Not always precise hexagons
• Topographical limitations
• Local signal propagation conditions
• Location of antennas
2
3
14

15. Cellular Geometries
15

16. Frequency Reuse
• Power of base transceiver
controlled
• Allow communications within cell
on given frequency
• Limit escaping power to adjacent
cells
• Allow re-use of frequencies in
moderate far cells
• Use same frequency for multiple
conversations
• 10 – 50 frequencies channel per cell
• E.g.
• N cells
• K total number of frequencies used
in the systems
• Each cell has K/N frequencies
• Advanced Mobile Phone Service
(AMPS) K=395, N=7 giving 57
frequencies per cell on average
16

17. Characterizing Frequency Reuse
• D = minimum distance between centers of cells that use the same band of frequencies
(called channels)
• R = radius of a cell
• d = distance between centers of adjacent cells (d = 3R)
• N = number of cells in repetitious pattern
• Each cell in pattern uses unique band of frequencies
• Hexagonal cell pattern, following values of N possible
• N = i2 + j2 + (i x j), i, j = 0, 1, 2, 3, …
• Possible values of N are 1, 3, 4, 7, 9, 12, 13, 16, 19, 21, …
• D/R=
• D/d =
N
3
N
17

18. Frequency Reuse Patterns
18

19. Increasing Capacity
• Add new channels
• Not all channels used to start with
• Frequency borrowing
• Taken from adjacent cells by congested cells
• Or assign frequencies dynamically
• Cell splitting
• Non-uniform distribution of topography and traffic
• Smaller cells in high use areas
• Original cells 6.5 – 13 km
• 1.5 km limit in general for smaller cells
• More frequent handoff
• More base stations
19

20. Cell Splitting
20

21. Increasing Capacity with cell splitting
• Cell Sectoring
• Cell divided into wedge shaped sectors
• 3–6 sectors per cell
• Each with own channel set
• Subsets of cell’s channels
• Uses directional antennas
• Microcells
• Move antennas from tops of hills and large buildings to tops of small
buildings and sides of large buildings
• Even lamp posts type BTs
• Reduced power
• Good for city streets, along roads and inside large buildings
21

22. Frequency Reuse Example
22

23. Operation of Cellular Systems
• Base station (BS) at center of each cell
• Antenna, controller, transceivers
• BS connected mobile telecommunications switching office (MTSO)
• One MTSO serves multiple BS
• MTSO to BS link by wire or wireless
• Controller handles call process
• Controls number of mobile units in use at a time
• MTSO:
• Connects calls between mobile units and from mobile to fixed telecommunications network
• Assigns voice channel
• Performs handoffs
• Monitors calls (billing)
• Fully automated
• Operated automatically
• Channels
• Control channels
• Setting up and maintaining calls
• Establish relationship between mobile unit and nearest BS
• Traffic channels
• Carry voice and data 23

24. Overview of Cellular System
24

25. Typical Call in Single MTSO Area
• Mobile unit initialization
• Scan and select strongest set up control channel
• Automatically selected BS antenna of cell
• Usually but not always nearest (propagation anomalies)
• Handshake to identify user and register location
• Scan repeated to allow for movement
• Change of cell
• Mobile unit monitors for pages
• Mobile originated call
• Check set up channel is free
• Monitor forward channel (from BS) and wait for idle
• Send number on pre-selected channel
• Paging
• MTSO attempts to connect to mobile unit
• Paging message sent to BSs depending on called mobile number
• Paging signal transmitted on set up channel
25

26. Typical Call in Single MTSO Area
• Call accepted
• Mobile unit recognizes number on set up channel
• Responds to BS which sends response to MTSO
• MTSO sets up circuit between calling and called BSs
• MTSO selects available traffic channel within cells and notifies BSs
• BSs notify mobile unit of channel
• Ongoing call
• Voice/data exchanged through respective BSs and MTSO
• Handoff
• Mobile unit moves out of range of cell into range of another cell
• Traffic channel changes to one assigned to new BS
• Without interruption of service to user 26

27. Call Stages
27

28. Other Functions of MTSO
• Call blocking
• During mobile-initiated call stage, if all traffic channels busy, mobile tries again
• After number of fails, busy tone returned
• Call termination
• User hangs up
• MTSO informed
• Traffic channels at two BSs released
• Call drop
• BS cannot maintain required signal strength
• Traffic channel dropped and MTSO informed
• Calls to/from fixed and remote mobile subscriber
• MTSO connects to PSTN
• MTSO can connect mobile user and fixed subscriber via PSTN
• MTSO can connect to remote MTSO via PSTN or via dedicated lines
• Can connect mobile user in its area and remote mobile user
28

29. Mobile Radio Propagation Effects
• Signal strength
• Strength of signal between BS and mobile unit strong enough to maintain
signal quality at the receiver
• Not strong enough to create too much co-channel interference
• Noise varies
• Automobile ignition noise greater in city than in suburbs
• Other signal sources vary
• Signal strength varies as function of distance from BS
• Signal strength varies dynamically as mobile unit moves
• Fading
• Even if signal strength in effective range, signal propagation effects may
disrupt the signal
29

30. Design Factors
• These factors determine size of individual cell
• Propagation effects
• It is dynamic
• Hard to predict the environmental condition
• Maximum transmit power level at BS and mobile units
• Typical height of mobile unit antenna
• Available height of the BS antenna
• Model based on empirical data
• Apply model to given environment to develop guidelines for cell size
• E.g. model by Okumura et al refined by Hata
• Detailed analysis of the required area
• Produced path loss information for an urban environment
• Hata's model is an empirical formulation
• Takes into account variety of environments and conditions 30

31. Fading
• Time variation of received signal
• Caused by changes in transmission path(s)
• E.g. atmospheric conditions (rain)
• Movement of (mobile unit) antenna
31

32. Multipath Propagation
• Reflection
• Due to large surface relative to wavelength of signal
• May have phase shift from original
• May cancel out original or increase its strength
• Diffraction
• Edge of impenetrable body that is large relative to wavelength
• May receive signal even if no line of sight (LOS) to transmitter
• Scattering
• Obstacle size on order of wavelength
• Scattering Occurs when a wave impinges upon an object with dimensions on the order of
l or less, causing the reflected energy to spread out or “scatter” in many directions.
• Small objects such as street lights, signs, & leaves cause scattering
• If LOS, diffracted and scattered signals not significant
• Reflected signals may be significant
• If no LOS, diffraction and scattering are primary means of reception
32

33. Reflection, Diffraction, Scattering
33

34. Effects of Multipath Propagation
•Signals may cancel out due to phase differences
•Intersymbol Interference (ISI)
•Sending narrow pulse at given frequency between fixed
antenna and mobile unit
•Channel may deliver multiple copies at different times
•Delayed pulses act as noise, making recovery of bit
information difficult
•Timing changes as mobile unit moves
• Harder to design signal processing to filter out multipath
effects
34

35. Two Pulses in Time-Variant Multipath
35

36. Types of Fading
• Fast fading
• Rapid changes in strength over distances about half wavelength
• 900MHz wavelength is 0.33m
• 20-30dB
• Slow fading
• Slower changes due to user passing different height buildings, gaps in
buildings etc.
• Cover longer distances than fast fading
• Flat fading
• Nonselective to distance
• Affects all frequencies in same proportion
• Selective fading
• Different frequency components affected differently
36

37. Error Compensation Mechanisms
• Forward error correction
• Applicable in digital transmission applications
• Big overhead
• Portion of capacity one-half or one-third
• Reflects difficulty or mobile wireless environment
• Adaptive equalization
• Applied to transmissions that carry analog or digital information
• Used to combat intersymbol interference
• Gathering the dispersed symbol energy back together into its original time
interval
• Techniques include lumped analog circuits and sophisticated digital signal
processing algorithms
37

38. Error Compensation Mechanisms
• Frequency and time Diversity
• Based on fact that individual channels experience independent fading events
• Provide multiple logical channels between transmitter and receiver
• Send part of signal over each channel
• Doesn’t eliminate errors
• Reduce error rate
• Equalization, forward error correction then cope with reduced error rate
• May involve physical transmission path
• Space diversity
• Multiple nearby antennas receive message or collocated multiple directional
antennas
• More commonly, diversity refers to frequency or time diversity
38

39. Basic Concepts: Multiple Access
• Multiple access schemes are used to allow many
mobile users to share a finite amount of radio
spectrum simultaneously.
• The sharing of spectrum is required to achieve
high capacity by simultaneously allocating the
bandwidth.
• Sharing a common resource requires an access
mechanism that will control the multiplexing
mechanism.
• Duplexing is generally required for multiple
access
39

40. Frequency division duplexing (FDD)
• Two bands of frequencies for every user
• forward band- provides traffic from the BS to the mobile
• reverse band- provides traffic from the mobile to the BS
• guard needed
• frequency separation between forward band and reverse band is constant
Reverse Channel Forward Channel
frequency
fc,R fc,,F
Frequency separation
Frequency separation should be carefully decided
40

41. Time division duplexing (TDD)
• Both directions of transmission use one contiguous frequency allocation, but
separated with time slots .
• Uses time for forward and reverse link
• multiple users share a single radio channel
• As a consequence of the use of the same frequency band, the communication
quality in both directions is the same.
F R R R R
0 1 2 3 4 5 6 7 …
….
Reverse
Channel
Forward
Channel
time
Ti
Time separation
Ti+1
channel
Slot number
F F F
41

42. Multiple Access Techniques
• The Most Common Multiple Access Techniques are
• Frequency division multiple access (FDMA)
• Time division multiple access (TDMA)
• Code division multiple access (CDMA)
42

43. Frequency Division Multiple Access (FDMA)
• In FDMA, each user is allocated a unique frequency band or channel.
• During the period of the call, no other user can share the same frequency band.
• idle time causes wasting of resources
• simultaneously and continuously transmitting
• All channels in a cell are available to all the mobiles.
• Channel assignment is carried out on a first-come first- served basis
• Allocation of separate channels to FDMA signals
• It is used for analog communication
43

44. Frequency Division Multiple Access (FDMA)
• Time-frequency characteristic of FDMA • FDMA compared to TDMA
• fewer bits for synchronization
• fewer bits for framing
• higher costs for duplexer used in base station
and subscriber units
• FDMA requires RF filtering to minimize
adjacent channel interference
44

45. Logical separation
• Logical separation FDMA/FDD • Logical separation FDMA/TDD
45

46. Time Division Multiple Access (TDMA)
• In each slot only one user is allowed to either transmit or receive - one user per slot
• Unlike FDMA, only digital data and digital modulation must be used.
• Each user occupies a cyclically repeating time slot
• buffer and burst method- The input data to be transmitted is buffered over the previous frame and burst transmitted at a
higher rate during the time slot for the channel.
• Non-continuous transmission
• Allocation of time slot in TDMA
46

47. Time Division Multiple Access (TDMA)
• Time-frequency characteristic of synchronous
TDMA
• Features of TDMA
• a single carrier frequency for several users
• transmission in bursts
• low battery consumption
• handoff process much simpler
• very high transmission rate
• high synchronization overhead
• guard slots necessary
47

48. Logical separation • Logical separation TDMA/TDD
48
f
t
user 1 user n
forward
channel
reverse
channel
forward
channel
reverse
channel
...
Logical separation TDMA/FDD
f
t
user 1 user n
forward
channel
reverse
channel
forward
channel
reverse
channel
...

49. TDMA, cont.
49

50. Code Division Multiple Access (CDMA)
• All users use the same carrier frequency and may transmit simultaneously
• Codes take the form of a carefully designed one/zero sequence produced at a much higher
rate than that of the baseband data.
• CDMA codes are not only required to provide call security, but create a uniqueness to
enable call identification.
• Codes should not correlate to other codes or time shifted version of itself.
• The code used are noise like pseudo-random codes.
50
k2 k3 k4 k5 k6
k1
f
t
c

51. Features of CDMA
• Each channel has a unique code
• All channels use the same spectrum at the same time
• bandwidth efficient
• coordination and synchronization not necessary
• good protection against interference and tapping
• more complex signal regeneration
• No guard time/band needed
• Enables soft handoff
51

52. Cellular generations
52

53. Cellular generations, cont.
53

54. First Generation Analog (1G)
• Original cellular telephone networks
• Created Early 1980s in North America
• Example: Advanced Mobile Phone Service (AMPS)
• Developed by AT&T
• Also common in South America, Australia, and China
• First-generation wireless technology is based on
analog signals.
• Mostly relied on FDMA/FDD and analog FM.
• Are very limited in capacity and did not extend
across geographic areas
• Systems using 1G :
• AMPS, TACS, and NMT
• Working of 1G
• In this, mobile device sends the waves to a base station
where they are processed to determine the signal’s, the
signal is reconstructed as accurately as possible at the
receiver
• The analog signal received by the end user may closely
resemble the original transmission but rarely duplicate it.
• Noticeable differences in quality and form occur due to:
• recreation errors.
• Signal destruction .
• translation and interference problems .
• Capacity (data rate): 2kbps
• Big cellphones:
54

55. Second generation (2G) systems
• Developed in Europe and US to provide better voice quality, higher capacity
as well as lower power consumption.
• Offer simple non-voice services like SMS(simple messaging service).
• Difficult roaming between countries using different systems.
• Can not meet subscriber demands for new, faster non-voice services on the
move.
• Its standards use digital modulation formats and TDMA/FDD and
CDMA/FDD multiple access techniques.
• Many of today’s cellular systems still use second generation (2G)
technologies
• While first generation systems relied on FDMA/FDD and only FM, second
generation standards use digital modulation and TDMA/FDD or
CDMA/FDD
55

56. Second generation (2G) systems, cont..
• The Standards include 3 TDMA standards and 1 CDMA:
A. Global System Mobile(GSM)
• It supports 8 time slotted users for each 200kHz radio channel
B. Interim Standard 136(IS-126)
• It supports 3 time slotted users for each 30KHz radio channel.
C. Pacific Digital Cellular
• It is similar to IS-136 with more than 50 users
D. CDMA one
• It supports up to 64 users that are orthogonology coded and transmitted on each
1.25MHz channel.
• 2G technologies offer a three times increase in spectrum efficiency
than 1G .
56

57. Key Specifications of leading 2G technologies-Frequency bands
Cdma One, IS-95, ANSI J-STD-008 GSM, DCS-1900, ANSI J-STD-007 NADC, IS-54/IS-136, ANSI J-
STD-011, PDC
Uplink Frequencies 824-849 MHz
(US Cellular)
1850-1910 MHz (US PCS)
890-915 MHz (Europe)
1850-1910 MHz (US PCS)
800 MHz, 1500 MHz (Japan)
1850-1910 MHz (US PCS)
Downlink
Frequencies
869-894 MHz
(US Cellular)
1930-1990 MHz (US PCS)
935-960 MHz (Europe)
1930-1990 MHz (US PCS)
869-894 MHz,
(US Cellular)
1930-1990 MHz (US PCS)
800 MHz, 1500 MHz (Japan)
57

58. Key specifications of leading 2G technologies-Modulation
Cdma One, IS-95, ANSI J-
STD-008
GSM, DCS-1900, ANSI J-
STD-007
NADC, IS-54/IS-136, ANSI J-
STD-011, PDC
Duplexing FDD FDD FDD
Multiple Access Technology CDMA TDMA TDMA
Modulation BPSK with Quadrature
Spreading
GMSK /4 DQPSK
Carrier Separation 1.25 MHz 200 kHz 30 kHz (IS-136)
(25 kHz for PDC)
58

59. Key specifications of leading 2G technologies-Data rate
CDMA One, IS-95,
ANSI J-STD-008
GSM, DCS-1900,
ANSI J-STD-007
NADC, IS-54/IS-136,
ANSI J-STD-011, PDC
Channel Data Rate 1.2288 Mb/s 270.833 kbps 48.6 kbps (IS-136)
(42kbps for PDC)
Voice Channels per
Carrier
64 8 8
Speech coding Code Excited Linear
Prediction (CELP) @
13kbps, Enhanced
Variable Rate Codec
(EVRC) @ 8 kbps
Residual Pulse
Excited Long Tern
Prediction (RPE-LTP)
@ 13 kbps
Vector Sun Excited
Linear Predictive
Coder (VSELP) @
7.95 kbps
59

60. Evolution of 2.5G Mobile radio networks
•Evolution from 2G  2.5G required to support
increased data rates for modern internet applications.
•2.5G are new data-centric standard that can be overlaid
on existing 2G technologies
•2.5G supports new web browsing format language
called WAP (Wireless applications Protocol)
60

61. • WAP enables standard web pages to be viewed in a
compressed format  suitable for small portable hand-
held wireless devices.
• First developed in Japan by NTT-DoCoMo  I-mode for
PDC network - supports games, color graphics and
interactive web pages using 9.6 kbps
• 25 million Japanese subscribers in 2001for this network
2.5G Mobile radio networks
61

62. 2.5G TDMA standards
• HSCSD (High Speed Circuit Switched Data) for 2.5G GSM
oAllows a single mobile user to use more than one specific time
slot as in GSM TDMA
oIncreases application rate from 9,600 bps (2G GSM) to 14,400
bps (2.5G GSM)
oIdeal for streaming internet access or real-time interactive web
sessions.
oCan be implemented by a software change at existing GSM base
stations.
62

63. 2.5G TDMA standards GPRS (General Packet Radio Service)
•GPRS for 2.5G GSM and IS-136
oPacket based data network suited for non-real time internet
usage
oE-mail retrieving, faxes download  upload
oGPRS can support more users that HSCSD
63

64. 2.5G TDMA standards EDGE (Enhanced Data GSM Environment)
• More advanced upgrade to GSM standard
• Regains additional hardware/software at existing base stations
• New digital modulation format (8-PSK/octal PSK)
• Raw data rate of 547.2 kbps possible with 8 GSM slots of a GSM
channel are allowed for each user
64

65. 2.5G CDMA standards
•IS-95B for 2.5G CDMA
•Medium data rate (MDR) service with throughput of
115.2 kbps per user (8 x 14.4 kbps)
•Advanced handoff procedures allows mobiles to
search different radio channels independently
65

66. Third generation (3G) wireless goals
• Unparalleled wireless access
• Multi Mbps Internet access using VoIP (Voice Over Internet Protocol),
voice activated calls
• Ability to receive live music, interactive web sessions, voice and data
access with multiple features at the same time, at all times
66

67. • ITU (International Telecommunications Union) proposed a
global frequency band in 2000 MHz range
• Single wireless communications standard for all countries in the world
IMT-2000.
• World community remains split between GSM/IS-136/PDC and CDMA
• IS-95
• Second generation CDMA scheme
• Transmission structures different on forward and reverse links
Third generation (3G) wireless methods
67

68. IS-95 Channel Structure
68

69. IS-95 Forward Link
• Up to 64 logical CDMA channels each occupying the same
1228-kHz bandwidth
• Four types of channels:
• Pilot (channel 0)
• Continuous signal on a single channel
• Allows mobile unit to acquire timing information
• Provides phase reference for demodulation process
• Provides signal strength comparison for handoff determination
• Synchronization (channel 32)
• 1200-bps channel used by mobile station to obtain identification information
about the cellular system
• System time, long code state, protocol revision, etc.
69

70. IS-95 Forward Link
• Paging (channels 1 to 7)
• Contain messages for one or more mobile stations
• Traffic (channels 8 to 31 and 33 to 63)
• 55 traffic channels
• Original specification supported data rates of up to 9600 bps
• Revision added rates up to 14,400 bps
• All channels use same bandwidth
• Chipping code distinguishes among channels
• Chipping codes are the 64 orthogonal 64-bit codes derived from
64  64 Walsh matrix
70

71. 2G - 3G evolution
IS-95 GSM
IS-136
& PDC
IS-95B
HSCSD
GPRS
HSCSD
cdma2000-1xRTT
Cdma2000-1xEV, DV, DO
cdma2000-3xRTT
W-CDMA
EDGE
TD-SCDMA
3GPP2
3GPP
71

72. Alternative Interfaces
•CDMA2000
• North American origin
• Similar to, but incompatible with, W-CDMA
• In part because standards use different chip rates
• Also, cdma2000 uses multicarrier, not used with W-CDMA
•IMT-SC designed for TDMA-only networks
•IMT-FC can be used by both TDMA and FDMA carriers
• To provide some 3G services
• Outgrowth of Digital European Cordless Telecommunications
(DECT) standard
72

73. 3G CDMA standard-W-CDMA
• 3G W-CDMA (UMTS - Universal Mobile Telecommunications
System)
• Packet based wireless service which enables computers,
entertainment devices, telephones to connect to internet anytime,
anywhere
• Packet data rates up to 2.048 Mbps per stationary user
• Broadcasting, VHE (Virtual Home Entertainment) m-commerce
(mobile commerce), games, interactive video, virtual private
technology - all possible from small portable wireless device
73

74. 3G CDMA standards-cdma2000
•3G cdma2000 or cmda2000 IX
•New high data rate internet access with backward
compatibility to IS-95 and IS-95B systems - 1.25 MHz
bandwidth
•Instantaneous data rate of 307 kbps in packet mode
•Both FDD (mobile radio) and TDD (in-building cordless)
applications
74

75. 3G TDMA standards
• 3G TD-SCDMA (Time Division Synchronous Code Division Multiple
Access)
• Developed by CATT (Chinese Academy of Telecommunications
Technology) and Siemens.
• Adopted by ITU as one of 3G options in 1999
• Existing GSM - 3G evolution through additions of high data rate equipment
in each GSM station - 1.6 MHz bandwidth
• Utilizes smart antennas, spatial filtering and joint detection technologies
75

76. Broadband wireless services
• Wireless Local Loop (WLL)
• Demand for broadband internet and computer access from
businesses and homes
• Fixed wireless equipment have advantages such as fixed path
between T-R
• Microwave or millimeter radio frequencies used >28GHz - wave
length is very small - small high gain antennas.
• Especially useful in developing nations with less
telecommunications setup
76

77. Broadband wireless services
• Wireless Local Area Networks (WLANS)
• UNII (Unlicensed National Information Infrastructure) hand
allocated by FCC for low power spread spectrum
• 5.150 - 5.35 GHz, 5.725 - 5.825 GHz (1997) ,902-928 MHz,
2400-2483.5MHz, 5.725-5.825 MHz (1980s end)
• IEEE 802.11 (1997) standard and IEEE 802.11b approved to
provide guidelines for WLAN manufacturers
77

78. IEEE 802.11 Wireless LAN
1 Mbps
DBPSK
2 Mbps
DQPSK
2 Mbps
4GFSK
1 Mbps
2GFSK
DSSS
FHSS Diffuse IR
850 TO 950 NM
2.4 GHZ
IEEE 802.11b
Extension
11 Mbps
DQPSK--CCK
BPSK--PBCC
5.5 Mbps
DQPSK--CCK
BPSK--PBCC
IEEE 802.11
78

79. High Performance Radio Local Area Network (HIPERLAN)
• Europe standard to provide similar capability to IEEE 802.11
• 5.2 GHz and 17.1Ghz frequency lands
• Up to 20 Mbps data rate at 50m range and vehicle speeds of
35km/hr
• Advanced standards include Europe’s ETSI-BRAN
(Broadband Radio Access Network) and HIPERLAN/2.
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80. Personal Area Networks (PANs)
• Ability to replace cables between devices with wireless short range
connection
• Bluetooth operates in 2.4GHz ISM band (2900-2483.5MHz) with 1 MHz
channel bandwidth
• Uses FH-SS TDD scheme with 1600 bps
• 1Mbps symbol rate using GFSK modulation
• IEEE 802.15 standards committee is our international forum for developing
Bluetooth and other PANS
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81. PAN Bluetooth standard
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82. Fourth Generation (4G) Systems
Long-Term Evolution (LTE ) is 4G wireless communication
standard for high-speed data up to 200 Mbps
This standard was initiated by NTT DoCoMo in 2004
4G is organized by Third Generation Partnership Project (3GPP)
Increase in capacity and speed due to new Modulation Technique
(Orthogonal Frequency Division Multiplexing (OFDM)
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83. Principle of high speed OFDM
Higher data rate implies narrower data pulse width:
For example 200 Mbps => 5 ns pulse
Narrow pulses are subject to instability and interference
Solution is to replace single channel carrier with several
subcarriers
Subcarriers have lower date rate with more stable pulse
widths
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84. Fifth generation (5G) systems
Very fast mobile network over dense urban areas
Use of Dynamic Spectrum Access (DSA) : allows secondary
users to access abundant spectrum holes in licensed spectrum
bands
Coordinated fiber-wireless network that uses the millimeter wave
bands (20 – 60 GHz) to allow very wide bandwidth radio
channels able to support data access speeds of up to 10 Gbps
Short Wireless links like Wi-Fi, with local fiber optic terminals
rather than long range cellular service
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