This slide is very fruitful for those engineering students who give high preference to communication subject like Telecommunication, Optical Fiber Communication and even Wireless communication.

1. Prepared By:-
-Er.Anup Bista
OPTICAL
FIBER
COMMUNICATION
EX 765 01
NATIONAL COLLEGE OF ENGINEERING
TALCHHIKHEL, LALITPUR

2.  Transmission paths run between the workstations
(computers , telephones , fax machines etc.) to
establish connections between them which forms
a collection of interconnected stations is called
NETWORKS
 Optical fiber acting as a transmission path
between workstation forming a network is known
as optical fiber network

4.  The Fiber Distributed Data Interface (FDDI)
specifies a 100-Mbps token-passing, dual-ring
LAN using fiber-optic cable.
 It defines the physical layer and media-
access portion of the link layer of OSI model
 FDDI is frequently used as high-speed
backbone technology because of its support
for high bandwidth and greater distances
than copper.
 It operates at faster speeds, FDDI is similar in
many ways to Token Ring.

5.  FDDI specifies the use of dual rings. Traffic
on these rings travels in opposite directions.
 Physically ,the rings consist of two or more
point-to-point connections between adjacent
stations.
 One of the two FDDI rings is called the
primary ring; the other is called the
secondary ring.
 The primary ring is used for data
transmission, while the secondary ring is
generally used as a backup or remains idle.

7.  FDDI defines two types of optical fiber:
single-mode and multimode. A mode is a ray
of light that enters the fiber at a particular
angle.
 Multimode fiber uses LED as the light-
generating device.
 And single-mode fiber generally uses lasers.

9.  The FDDI frame format is similar to the
format of a Token Ring frame.
 FDDI frames can be as large as 4,500 bytes.

10.  Preamble:-Gives a unique sequence that prepares each station for an upcoming frame.
 Start delimiter:-Indicates the beginning of a frame by employing a signaling pattern that
differentiates it from the rest of the frame.
 Frame control:-Indicates the size of the address fields and whether the frame contains
asynchronous or synchronous data, among other control information.
 Destination address:-Contains a uni-cast (singular), multicast (group), or broadcast (every
station) address. As with Ethernet and Token Ring addresses, FDDI destination addresses are 6
bytes long.
 Source address:-Identifies the single station that sent the frame. As with Ethernet and Token
Ring addresses, FDDI source addresses are 6 bytes long.
 Data:-Contains either information destined for an upper-layer protocol or control information.
 Frame check sequence (FCS):-Is filed by the source station with a calculated cyclic redundancy
check value dependent on frame contents (as with Token Ring and Ethernet). The destination
address recalculates the value to determine whether the frame was damaged in transit. If so,
the frame is discarded.
 End delimiter:-Contains unique symbols; cannot be data symbols that indicate the end of the
frame.
 Frame status:-Allows the source station to determine whether an error occurred; identifies
whether the frame was recognized and copied by a receiving station.

12.  SONET is a synchronous network. A single
clock is used to handle the timing of
transmissions and equipment across the
network.
 SONET are standardized protocols that
transfer multiple digital bit streams
over optical fiber using lasers or
highly coherent light from light-emitting
diodes (LEDs).

13.  SONET defines a technology for carrying many
signals of different capacities through a
synchronous, flexible, optical hierarchy.
 SONET provides :-
− Multiplexing.
− Error checking.
− Handling variations in clocks.
− Mapping of plesiochronous(nearly the same)voice
and data traffic.
− Signaling for automatic switching in case of a
fiber or node failure.

14.  SONET encodes bit streams into optical signals
propagated over optical fiber.
 All clocks in the network are locked to a common
master clock so that simple TDM can be used.
 Multiplexing done by byte interleaving.
 SONET defines a hierarchy of signaling levels called
synchronous Transport Signals (STS).
 Each STS level (STS-1 to STS-192) supports a
certain data rate, specified in megabits per
second.
 The physical links defined to carry each level of
STS are called optical carriers (OCs).

15.  Increased bandwidth over traditional
telecommunication system
 Increased configuration flexibility that
supports future applications, with variety of
transmission rates
 Reduction in equipment requirement
 An increase in network reliability and many
more …

16.  The basic building block of SONET is the STS-1
frame. The length of this frame is defined by the
number of bits it is possible to transmit in 125us at
the clock rate of the network link.

17.  9 rows by 90 columns – 810 octets in the frame.
 Frame is transmitted from left to right, by row.
 Frames are transmitted 8,000 times per second,
every 125 μseconds.
 STS-1 bit rate is therefore 51.84 Mbps (810 octets
x 8,000 times per second x 8 bits per octet).
 This lowest level SONET signal is called a
Synchronous
 Transport Signal, level 1 (STS-1). Once the
scrambler is applied, it is known as an Optical
Channel, level 1 (OC-1).
 The lowest level SDH signal is know as a
Synchronous Transport Module, level 1 (STM-1).

19.  STS multiplexer/ demultiplexer:
- Either multiplexes signals from multiple sources into
an STS Or
- Demultiplexes an STS into different destination signals.
 Regenerator:
- Function at the data link layer.
- Takes a received optical signal and regenerates it.
- Add a function to those of physical layer repeaters.
- Replaces some of the existing overhead information
with new information.
 Add/drop multiplexer:
- Add signals from different sources into a given path Or
- Remove a desired signal from a path and redirect it
without demultiplexing the entire signal.