Gives you a very good brief vision about how tele communications works and different types of telecommunications also gives a brief vision about optical fiber and working OFC

1. Tele Communication &
Fibre Optics
A Brief Vision of Internship
Swamy Surya Teja
B.Tech in ECE
KL University

2. Introduction
All About
PCM & Mux

3. PCM: Pulse Code Modulation
• The essential operations in the transmitter of PCM
system Sampling, quantizing and encoding .
• The quantizing and encoding are performed in same
circuit called analog to digital converter.
• The essential operations in the receiver are
regeneration of impaired signals, decoding and
demodulation of train of quantized samples. These
operations are performed in same circuits called digital
to analog converter.
• The intermediate points are regenerative repeaters to
reconstruct the transmitted sequence of coded pulses.

5. 5
Multiplexing….
• Why need came to go for
Multiplexing Techniques ?

8. 8
CO Switch
CO Switch
8 Pairs
of Cable
Interconnectivity
between Exchanges
As the number of
customers increase the
pairs also be increased
Very Expensive

9. Mux : Multiplexing
• The Multiplexing of two ways : TDM & FDM
• TDM : Time Division Multiplexing
• FDM : Frequency Division Multiplexing
• In analog system, multiplex equipment uses
F.D.M. to assemble individual channels into
groups, super group etc. Similarly, in digital
systems, hierarchical levels have been
defined using T.D.M. and are identified by
their digit rate measured in No. of bits/sec.

10. FDM
• The FDM techniques is the process of translating
individual speech circuits (300-3400 Hz) into pre-
assigned frequency slots within the bandwidth of
the transmission medium.
• The frequency translation is done by amplitude
modulation of the audio frequency with an
appropriate carrier frequency.
• At the output of the modulator a filter network is
connected to select either a lower or an upper
side band

11. F
D
M
P
R
I
N
C
P
L
E

14. 14

15. Signaling/Switching
Analog and Digital way of Switching

16. Signaling
• Signaling
Signaling refers to the exchange of
information between call components
required to provide and maintain service
• The signaling formats and the requirements
for the subscriber, the trunks and the
subsystems differ significantly. Accordingly a
switching system provides 3 different forms of
signaling.
– subscriber loop signaling
– inter exchange signaling
– intra exchange or register signaling

17. Signaling: Pictorial Representation
Telephone
Exchange
Telephone
Exchange
withinexchange
betweenSubscriber
and exchange
between
exchanges

18. Types of Signaling
• Subscriber line Signaling
1) Calling Subscriber line Signaling
– Call request
– Address signal
• Decadic dialing
• DTMF
– End of the signal
– Answerback signal
– Release signal
– Permanent Line Signal
2) Called Subscriber Line Signals
– Ring Signal
– Answer Signal
– Release Signal
– Register Recall Signal
• Inter-exchange signaling
– Line Signaling
• DC signaling
• In-band and Out-band Signals
• E&M Signals
– Register Signals
– R2 Signaling
– Digital Signaling
• CAS
• CCS

19. Switching (Digital)
• A Digital switching system, in general, is one in
which signals are switched in digital form.
These signals may represent speech or data.
The digital signals of several speech samples
are time multiplexed on a common media
before being switched through the system.

20. Cont…
• To connect any two subscribers, it is necessary
to interconnect the time-slots of the two
speech samples which may be on same or
different PCM highways.
• The digitalized speech samples are switched in
two modes,
– Time Switching &
– Space Switching.

21. Digital Switching System (DSS)
• This Time Division Multiplex Digital Switching
System is popularly known as Digital Switching
System(DSS).
• Types of DSS
Space Division DSS
Time Division DSS

22. 22
Time and Space switching
• Generally, a digital switching system has several time
division multiplexed (PCM) samples. These PCM
samples are conveyed on PCM highways (the
common path over which many channels can pass
with separation achieved by time division).
• Switching of calls in this environment , requires
placing digital samples from one time-slot of a PCM
multiplex in the same or different time-slot of
another PCM multiplex.

23. 23
Time and Space switching
• In the space-switching mode, corresponding time-
slots of I/C and O/G PCM highways are
interconnected.
• As a sample, in a given time-slot, TSi of an I/C HWY,
say HWY1, is switched to same time-slot, TSi of an
O/G HWY, SAY HWY2. Obviously there is no delay in
switching of the sample from one highway to
another highway since the sample transfer takes
place in the same time-slot of the PCM frame

24. 24
Time and Space switching
• Time Switching, on the other hand, involves the
interconnection of different time-slots on the
incoming and outgoing highways by re-assigning the
channel sequence.
• For example, a time-slot TSx of an I/C Highway can
be connected to a different time-slot., TSy, of the
outgoing highway. In other words, a time switch is,
basically, a time-slot changer.

25. 25

26. 26
Space Division Switching
• The Digital Space Switch consists of several input
highways, X1, X2,...Xn and several output highways,
Y1, Y2,.............Ym, inter connected by a cross point
matrix of n rows and m columns. The individual cross
point consists of electronic AND gates. The operation
of an appropriate cross point connects any channel-a
of I/C PCM highway to the same channel-a of O/G
PCM highway, during each appropriate time-slot
which occurs once per frame

27. 27
Cont…
• Each cross point column, associated with one O/G
highway, is assigned a column of control memory.
The control memory has as many words as there are
time-slot per frame in the PCM signal
• Each cross point in the column is assigned a binary
address, so that only one cross point per column is
closed during each time-slot. The binary addresses
are stored in the control memory, in the order of
timeslots.

28. 28
Cont…
• As an Example, Consider the transfer of a
sample arriving in TS7 of I/C HWY X1 to O/G
HWY Y3. Since this is a space switch, there will
be no reordering of time i.e., the sample will
be transferred without any time delay, via the
appropriate cross point. In other words, the
objective is to connect TS7 of HWY X1 and TS7
of HWY Y3.

29. 29
Cont…
• The central control (CC) selects the control
memory column corresponding output
highway Y3. In this column, the memory
location corresponding to the TS7 is chosen.
The address of the cross point is written in this
location.
• This cross point remains operated for the
duration of the time-slot TS7, in each
successive frame till the call lasts.

30. 30
Cont…
• For disconnection of call, the CC erases the
contents of the control memory locations,
corresponding to the concerned time-slots.
The AND gates, therefore, are disabled and
transfer of samples is halted.

31. 31
Time Division Switching
• A Digital Time Switch consists of two
memories, viz., a speech or buffer memory to
store the samples till destination time-slots
arrive, and a control or connection or address
memory to control the writing and reading of
the samples in the buffer memory and
directing them on to the appropriate time-
slots.

32. 32
Cont…
• Speech memory has as many storage locations
as the number of time-slots in input PCM,
e.g., 32 locations for 32 channel PCM system.
• The writing/reading operations in the speech
memory are controlled by the Control
Memory. It has same number of memory
locations as for speech memory, i.e., 32
locations for 32 channel PCM system.

33. 33
Cont…
• Each location contains the address of one of
the speech memory locations where the
channel sample is either written or read
during a time-slot.
• These addresses are written in the control
memory of the CC of the exchange, depending
upon the connection objective.

34. C-DOT Switches
Latest TeleComm Switches

35. Different Types of
Electronic Switches
 C-DOT : Indian Made
 E10B : France Made
 OCB : France Made
 EWSD : Germany Made
 5ESS : USA Made

36. Simply C-DOT Mean
»C – Center for
»D – Development
»O – Of
»T – Telematics

37. C-DOT
Switching
Systems

38. C-DOT DSS FAMILY
• C-DOT DSS MAX is a universal digital switch which
can be configured for different applications as local,
transit, or integrated local and transit switch. High
traffic/load handling capacity up to 8,00,000 BHCA
with termination capacity of 40,000 Lines as Local
Exchange or 15,000 trunks as Trunk Automatic
Exchange, the C-DOT DSS family is ideally placed to
meet the different requirements of any integrated
digital network.

39. C-DOT DSS FAMILY
• The C-DOT is having 4 types of Exchanges.
(1)C-DOT 128 RAX.
(2)C-DOT 256P RAX.
(3)C-DOT SBM.
(4)C-DOT MBM.
– All the above Switching Systems are known as
Digital Switching Systems (DSS) Family.

40. C-DOT AN-RAX SWITCH

41. C-DOT SBM
• It is the THIRD generation of C-DOT DSS Family.
• It is the DOUBLE the size of C-DOT 256P RAX and
also serves Rural Areas and Small Urban Areas.
• It has a total of 2024 terminations and it contains 10
frames, Base Module (BM) have 488 terminations
and LM1 have 768 terminations and LM2 have 768
terminations.
• It is a Rural Automatic Exchange.
• It is controlled locally by Input-output processor
(IOP) Module.
• It is now replaced by C-DOT RBM’s (Remote Base
Modules).

42. Single Base Module
ATU (TIC 2)
ATU (TIC 3)
ATU (TIC 4)
ATU (TIC 10)
ATU (TIC 11)
ATU (TIC 12)
ATU (TIC 1)
ATU (TIC 5)
ATU (TIC 9)
ATU (TIC 13)
BPU
TSU
ATU (TIC 6)
ATU (TIC 7)
ATU (TIC 8)
ATU (TIC 14)
ATU (TIC 15)
ATU (TIC 16)
L
M
1
B
M
L
M
2

43. C-DOT SBM

44. C – DOT MBM
• It is the FOURTH generation of C-DOT DSS
Family.
• It is also called as MAX (Main Automatic
Exchange) and serves Urban Areas.
• C-DOT MAX is of 2 types
– MAX – L (Large) up to 16 no of BM’s are
connected to MAX.
– MAX – XL (Extra Large) up to 32 no of BM’s are
connected to MAX.

45. Cont…
• MAX-L has a capacity of 20,000 Lines +
3,000 Trunks.
• MAX-XL has a capacity of 40,000 Lines +
6,000 Trunks.
• It is a Main Automatic Exchange.
• It is controlled by Input-output processor
(IOP) Module at OMC.

46. C – DOT MBM
• C-DOT DSS MAX exchanges can be configured
using four basic modules
→Base Module
→ Central Module
→Administrative Module

47. Base Module
The Base Module (BM) is the basic growth
unit of the system. It interfaces the external
world to the switch. The interfaces may be
subscriber lines, analog and digital trunks,
CCM and PBX lines. Each Base Module can
interface up to 2024 terminations.

48. – Central Module (CM) consists of a message switch
and a space switch to provide inter – module
communication and perform voice and data
switching between Base Modules.
– It provides control message communication between
any two Base Modules, and between Base Modules
and Administrative Module for operation and
maintenance functions. It also provides clock and
synchronization on a centralized basis.
Central Module

49. – It performs system-level resource allocation and
processing function on a centralized basis.
– It performs all the memory and time intensive call
processing support functions and also administration
and maintenance functions.
– It communicates with the Base Module via the Central
Module.
– It supports the Input Output Module for providing man -
machine interface.
– It also supports the Alarm Display Panel for the
audiovisual indication of faults in the system.
Administrative Module

50. – Input Output Module (IOM) consists of duplicated
Input Output Processor (IOP).
– The Input Output Processor (IOP) is a general-
purpose computer with UNIX Operating System.
– It is used as the front-end processor in C-DOT DSS. It
handles all the input and output functions in C-DOT
DSS.
– The IOP is connected to AP/BP via HDLC links.
Input Output
Module

51. M
B
M
Architecture

52. Mobile Communication
Briefly about GSM

53. GSM
Global System for Mobile
Communications

54. Public Land Mobile Network
• INDIA has adopted GSM standard for PLMN.
• Digital Cellular System.
• Operates at 900 MHz.
• International Roaming facility.
• Power class 0.8 to 20W.
• Cell Radius upto 35 Kms.
• Maximum mobility speed 250 Km/hr.

55. GSM900 :
up: 890~915MHz
down: 935~960MHz
duplex interval: 45MHz
bandwidth: 25MHz，
frequency interval: 200KHz
GSM1800 :
up: 1710-1785MHz
down: 1805-
1880MHz
duplex interval:
95MHz， working
bandwidth: 75MHz，
frequency interval:
200KHz
GSM1900MHz:
up:1850~1910MHz
down:1930~1990MHz
duplex interval: 80MHz，
working bandwidth: 60MHz，
frequency interval: 200KHz
EGSM900 :
up: 880~890MHz
down: 925~935MHz
duplex interval: 45MHz
bandwidth: 10MHz，
frequency interval:
200KHz
G
S
M
F
R
E
Q
U
E
N
C
Y
B
A
N
D
S

56. BANDWIDTH MANAGEMENT TECHNIQUES
• FDMA
• TDMA
• Cellular Technology & Frequency Re-use
Scheme

57. FDMA
• Frequency Division Multiple Access Scheme
• Uplink Frequency Band = (890 – 915) MHz
• Downlink Frequency Band = (935 – 960) MHz
• Absolute Radio Freq Carrier Number (ARFCN)
• Bandwidth = 915 – 890 or 960 – 935
= 25 MHz

58. 58
GSM-FDMA
25 MHz 25 MHz
Mobile to Base
0 1 2
890.2 890.4 890.6
(MHz)
Base to Mobile
0 1 2
935.2 935.4 935.6
200 kHz
45MHz
Channel layout and frequency bands of operation
890 935 960915
200 kHz

59. TDMA
• Time Division Multiple Access Scheme
• One Radio Frequency = Eight Time Slots
• One TDMA Frame = Eight Time Slots
• One Time Slot = One Physical Channel
• One Time Slot Duration = 0.577 m.sec

60. 60
GSM-TDMA
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
45 MHz
Frequency
F2’F1’
(Cell transmit)
F2F1
(Cell Rx)
Amplitude
Typical TDMA/ FDMA frame structure

61. Cellular Technology
• Cell
• Site
• Cluster

62. 62
CELL
A base station (transmitter) having a number of RF channels
is called a cell.
Each cell covers a a limited number of mobile subscribers
within the cell boundaries ( Coverage area)
Typical Cell Radius Aprrox = 30 Km (Start up), 1 Km
(Mature).
 Types of Cells
•OMNI CELLS
•SECTOR CELLS
- Two Sector Cells
- Three Sector Cells

63. CLUSTER

64. R.T.T.C. HYDERABAD 64
A CLUSTER OF CELLS
4
5
6
7
2
3
1
1 2 3 4 5 6 7
GIVEN FREQ.
RESOURCE
CELLULAR MOBILE CONCEPTS

65. R.T.T.C. HYDERABAD 65
CLASSIFICATION OF CELLS
• MICRO CELL
• MACRO CELL
• UMBRELLA CELL

66. 66
Handover
• Hard Handover – Break before make
• Soft Handover – make before break
• Softer Handover

67. R.T.T.C. HYDERABAD 67
Handovers

68. R.T.T.C. HYDERABAD 68
GSM
Evolution
GPRS
200 KHz carrier
115 Kbps peak data
rates
EDGE
200 KHz carrier
Data rates up to 384 Kbps
8-PSK modulation
Higher symbol rate
UMTS
5 MHz carrier
2 Mbps peak data rates
New IMT-2000 2 GHz spectrum
GSM
200 KHz carrier
8 full-rate time slots
16 half-rate time slots
GSM GPRS EDGE UMTS
3G2.5G2G
HSCSD
HSCSD
Circuit-switched data
64 Kbps peak data rates

69. R.T.T.C. HYDERABAD 69
2.5G-GPRS Vs 2G-GSM
2.5G – GPRS (GSM Advanced) 2G-GSM
SUPPORTS BOTH CKT.
SWITCHED as well as packet
switched service.
Only circuit
switched.
MS Utilizes Automatic retransmission
(ARQ) at data link layer to re-transmit
error frames.
No re-transmission
is provided.
Multiple time slots can be allotted to a
single user
Single time slot per
user.
One time slot can be allotted to several
users.
Single time slot per
user.
Charging/ billing more complex
(Volume based, Q.O.S. based)
Simple time-based
billing.

70. R.T.T.C. HYDERABAD 70
GPRS Network
HLR
Air (Um)
Gb
Gs
Gr Gf
Gn
Gn
Inter-PLMN
GPRS
Backbone
Gp
External
packet
network
Gi
SGSN
EIR
BSC
MSC/
VLR
SMS-
GMSC
Gd
GGSN
GGSN
Signalling and data
Signalling

71. Broad Band Technology
Wireline Vs Wireless

72. BROADBAND CONNECTIVITY
• What is Broadband?
– Always ON
– Speed of 256Kbps or more (As per TRAI).
– No Universal Agreement.
• ITU-T: Greater than Primary rate (1.5-2Mbps)
• ACCC( and FCC): Greater than 200Kbps
• OECD: Greater than 256Kbps.

74. 1. Personal Services
High Speed Internet Access
Multimedia
2. Govts. Public services
E-governance
E-education
Tele-medicine
3. Commercial services
E-commerce
Corporate Internet
Videoconferencing
4. Video & Entertainment
services
Broadcast TV
Video on Demand
Interactive gaming
Music on Demand
Online Radio
Applications of Broadband

75. Applications of Broadband

76. Broadband Technologies
Wireless Wireline
DSL (Digital Sub’s Line)
Cable Modem
Optical Fibre Technologies
PLC
(Power Line Communication)
3G Mobile
Wi-Fi (Wireless Fidelity)
LMDS & MMDS
FSO (Free Space Optics)
Satellite
WiMAX
Broadband Access Technologies

77. Broadband Access Technologies
PUBLIC NETWOKS
(IncludingInternet)
Copper Media:
1.ISDN
2. xDSL (VDSL, ADSL..etc)
Wireless:
1.Wi-Fi
2. WiMAX
3.3G Mobile.
4.Wireless in Local Loop
Optical Fiber:
1.FTTH
2. FTTC
3. .FTTN.
Cable Network
Broadband over
Power Lines
Satellite

78. Factors in Broadband Access Choices
• Population density
• Existing infrastructure (e.g., twisted pair, cable,
fiber)
• Government policies
• Technology evolution
Farm
Homes
MDUGigE Fiber
Cable modem
Twisted pair DSL
Satellite
City: High-rise
multi-family units
Suburbs:
Individual single-
family units
Rural: isolated
single family unit

79. Broadband
Wireline Access

80. Digital Subscriber Line (DSL) is the next generation
modem-like technology that allows for the
transmission of voice, video and data over existing
copper telephone lines at incredible megabit speeds.
The copper telephone lines are often referred to as
the local loop or the last mile from the Exchanges to
the end-user's home or business.
Digital Subscriber Line (DSL)

81. DSL may offer more than 100 times the
network performance of a traditional analog
modem
DSL uses the same telephone line as
traditional modem
DSL remains always-on all the time
– Customer no longer need to physically dial up to
the ISP to “log in to the internet”
DSL
Technology

82. DSL Technology
• DSL family:
 High bit rate Digital Subscriber Line (HDSL)
 Asymmetrical Digital Subscriber Line (ADSL)
 Very high-speed Digital Subscriber Line (VDSL)
 Single-pair High Speed Digital Subscriber Line (SHDSL)
 ISDN based Digital Subscriber Line (IDSL)

83. Asymmetric Digital Subscriber Line
Used for applications which require greater
download bandwidth but require relatively
little in opposite direction like Web browsing;
File downloads
An ADSL on a twisted pair telephone line
creating three information channels
– A high speed downstream channel
– A medium speed duplex channel
– A basic telephone service channel
ADSL

84. The basic telephone service channel is split off
from the digital modem by splitter at client site
Allows simultaneous access to the line by the
telephone and the computer
In case of power/ADSL failure, data transmission
is lost but basic telephone service will be
operational
Provides
– 256Kbps to 1000 Kbps upstream
– 1.5-24 Mbps downstream
Can work up to a distance of 3.7 to 5.5 kms
depending upon the speed required
ADS
L

85. ADSL rates and channel
frequency
band allocation in local loop

86. Data Rate - Wire Size – Distance
ADSL
Data Rate Wire Guage Distance
1.5-2.0 Mbps 0.5 mm 18000 Feet 5.5 Kms
1.5-2.0 Mbps 0.4 mm 15000 Feet 4.6 Kms
6.1 Mbps 0.5 mm 12000 Feet 3.7 Kms
6.1 Mbps 0.4 mm 9000 Feet 2.7 Kms
where
l is the length of the conductor, measured in meters
A is the cross-sectional area, measured in square
meters
ρ (Greek: rho) is the electrical resistivity (also called
specific electrical resistance) of the material,
measured in Ohm · meter. Resistivity is a measure of
the material's ability to oppose electric current.

87. Central OfficeHome/Office
ADSL
CPE
Curb
ADSL up to 5Km
SHDSL (PAM16) up to 5Km
SHDSL
Splitter
DSLAM
Data switch
Voice Switch
ADSL Deployment Today

88. Broadband Access using ADSL
INTERNET
PSTN
Router
DSLAM
CONTENT
PROVIDER
VIDEO ON
DEMAND SERVER
VIDEO ON
DEMAND SERVER
PHONE
INTERNET ACCESS
VIDEO ACCESS
ATM
SW

89. • High bit/data rate DSL
• Can be viewed as equivalent of PCM stream
• Offers the same bandwidth both upstream and
downstream
• Can work up to a distance of 3.66 to 4.57 kms
depending upon the speed require.
• No provision exists for voice because it uses the
voice band
• Can deliver 2048 kbps
– On 2 phone lines, each line carrying 1168 kbps
– On 3 phone lines, each line carrying 784 kbps
• HDSL-2 is proposed as next generation HDSL over
single phone line
– Requires more aggressive modulation, shorter
distance and better phone line

90. Symmetric Digital Subscriber Line
Rate adaptive version of HDSL
Does not support analog calls
Works up to 3.7 kms on 0.5 mm dia cable
Affordable alternative to dedicated leased
lines
SHDSL – Symmetric High – bit – rate Digital
Subscriber Line is an further improvement
over HDSL/SDSL and uses single phone line
SDSL

91. Very-high Data-rate DSL
Originally named VADSL (A –Asymmetric) but
was later extended to support both symmetric
& asymmetric
Requires one phone line
Supports voice & data
Works between 0.3-1.37 kms depending on
speed
VDSL

92. Upstream data rate of 1.6-2.3 mbps
Downstream data rate of 13-52 mbps
Data Rate - Wire Size – Distance
Downstream Upstream Distance
12.96 Mbps 1.6-2.3 mbps 4500 Feet 1.37 Kms
25.82 Mbps 1.6-2.3 mbps 3000 Feet 0.91 Kms
51.84 Mbps 1.6-2.3 mbps 1000 Feet 0.30 Kms
VDSL

93. Broadband
Wireless Access

94. Broadband Wireless Access
Technologies
• Wireless Access Technologies
– Wireless Personal Area Network (WPAN/
Bluetooth) (IEEE 802.15)
– Wireless Local Area Network (WLAN / WiFi) (IEEE
802.11)
– Wireless Metropolitan Area Network (WMAN /
WiMax) (IEEE 802.16)
– Fixed Broadband Wireless Access (LMDS/MMDS)
– Cellular Mobile Telephony (GSM-GPRS,EDGE /
CDMA 2000 1x EVDO,EVDD) (3G-UMTS/WCDMA)

95. Global Wireless Standards
WAN
IEEE 802.20
(Proposed)
3GPP, EDGE
(GSM), CDMA 2000-1x EV-DO
WCDMA,UMTS,4G
MAN
IEEE 802.16
Wireless MAN
ETSI HIPERMAN
& HIPERACCESS
LAN
IEEE 802.11
Wireless LAN
ETSI
HYPERLAN
IEEE 802.15
Bluetooth
ETSI
HYPERPAN
PAN

96. WPAN, (Bluetooth), IEEE- 802.15
• What is Bluetooth ?
– Wireless LAN technology (10 meters) PAN
– 2.4 Ghz band with 20+ Mbps speed
– Spread spectrum frequency hopping
– “Always on “ user transparent cable replacement
– Combination of circuit switching and packet
switching (good for voice and data)
– 3 Voice channels of 64 Kbps each

97. Bluetooth
 A new short-range wireless technology.
 It’s designed for:
 Interconnecting computer and peripherals.
 Interconnecting various handhelds.

98. What is Wireless LAN / WiFi

99. WLAN (WiFi), IEEE 802.11
• Wireless Ethernet standards
– IEEE 802.11
• The Initial release of the standard capable of transmissions of 1 to 2
Mbps and operates in 2.4 GHz band using either frequency hopping spread
spectrum (FHSS) or direct sequence spread spectrum (DSSS).
– IEEE 802.11a
• Capable of transmissions upto 54 Mbps and operates in 5 GHz band and
uses an orthogonal frequency division multiplexing OFDM encoding scheme .
– IEEE 802.11b
• Capable of transmissions of upto 11 Mbps and operates in 2.4 GHz band
and uses only DSSS encoding scheme.
– IEEE 802.11g
• Capable of transmissions upto 20+ Mbps and operates in 2.4 GHz band

100. What is WiMAX / IEEE802.16 ?
• IEEE 802.16 MAN standard
Worldwide Interoperability for Microwave Access (WiMAX)
– Will be able to connect 802.11 hotspots to the Internet, Can provide E1
level connectivity to enterprises, broadband access to home/SOHO
users, normal POTS can also be extended to the users. It can offer packet
switched as well as circuit switched connectivity.
– Provides up to 50 KMs (Max.) of service area range
– Has developed a point-to-multipoint broadband wireless access standard
for systems in the frequency range 10-66 GHz and sub 11 GHz.
– The standard covers both MAC and PHY layers

101. WiMax Applications
• According to WiMax Forum it supports 5
classes of applications:
◊ Multi-player Interactive Gaming.
◊ VOIP and Video Conference
◊ Streaming Media
◊ Web Browsing and Instant Messaging
◊ Media Content Downloads

102. OFC
Brief Vision of Optical Fibre

103. 103
 Common carrier nationwide networks.
 Telephone Inter-office Trunk lines.
 Customer premise communication networks.
 Undersea cables.
 High EMI areas (Power lines, Rails, Roads).
 Factory communication/ Automation.
 Control systems.
 Expensive environments.
 High lightening areas.
 Military applications.
 Classified (secure) communications
Applications of Optic Fibres

104. 104
Transmission Sequence
8000

105. 105
 Information is Encoded into Electrical Signals.
 Electrical Signals are Converted into light Signals.
 Light Travels Down the Fiber.
 A Detector Changes the Light Signals into
Electrical Signals.
 Electrical Signals are Decoded into Information.
 Inexpensive light sources available.
 Repeater spacing increases along with operating
speeds because low loss fibres are used at high
data rates
Transmission Sequence

106. 106
• By Snell's law, n1 sin  1 = n2 sing  2
• The critical angle of incidence  c where  2 = 90
o
• Is c = arc sing (n2 / n1)
• At angle greater than c the light is reflected,
Because reflected light means that n1 and n2 are
equal (since they are in the same material),  1
and  2 are also equal.
• The angle of incidence and reflection are equal.
These simple principles of refraction and reflection
form the basis of light propagation through an
optical fibre.
THEORY AND PRINCIPLE OF FIBRE OPTICS

107. 107
Principle of Total Internal Reflection.
ø1
Angle of incidence
n1
n2
ø2
n1
n2
ø1
ø2
n1
n2
ø1 ø2
Angle of
reflection
Light is bent away
from normal
Light does not enter
second material

108. 108
Propagation of light thro fibre
The optical fibre has two concentric layers
called the core and the cladding. The inner
core is the light carrying part.
 The surrounding cladding provides the
difference refractive index that allows total
internal reflection of light through the core.

109. 109
Jacket
Cladding
Core
Cladding
Angle of
reflection
Angle of
incidence
Light at less than
critical angle is
absorbed in jacket
Jacket
Light is propagated by
total internal reflection
Jacket
Cladding
Core
(n2)
(n2)
Fig. Total Internal Reflection in an optical Fibre
Propagation of light through fibre

110. 110
Construction of O F Cable
• An Optical fibre consists of a core of optically
transparent material usually silica or
borosilicate glass surrounded by a cladding of
the same material but a slightly lower
refractive index.
• Fibre themselves have exceedingly small
diameters. Figure shows cross section of the
core and cladding diameters of commonly
used fibres. The diameters of the core and
cladding are as follows

111. 111
Cont…
125 8 125 50 125 62.5 125 100
Core Cladding
Typical Core and Cladding Diameters
Core (m) Cladding ( m)
8 125
50 125
62.5 125
100 140

112. FIBRET
Y
P
E
S
O
F

113. ATTENUATION
ATTENUATION
Intrinsic Extrinsic

114. 114
INTRINSIC ATTENUATION
• It is loss due to inherent or within the fibre.
Intrinsic attenuation may occur as
• (I) Absorption - Natural Impurities in the glass
absorb light energy.
Light
Ray

115. 115
Cont …
• Scattering - Light rays travelling in the core reflect
from small imperfections into a new pathway that
may be lost through the cladding.
• Absorption - Natural Impurities in the Glass Absorb
Light Energy.
Light
Ray
Light is lost

116. 116
EXTRINSIC ATTENUATION
• It is loss due to external sources. Extrinsic
attenuation may occur as –
• Macro bending - The fibre is sharply bent so
that the light travelling down the fibre
cannot make the turn & is lost in the
cladding.
• Micro bending – Micro bending or small
bends in the fibre caused by crushing
contraction etc. These bends may not be
visible with the naked eye.

117. 117
EXTRINSIC ATTENUATION
Micro bend
Micro bend
Fig. Loss and Bends
Micro bend

119. F
U
S
I
O
N
S
P
L
I
C
E

120. B
R
O
A
D
B
A
N
D
SECTION

121. CONT …