UNDERSTAND THE TRANSMISSION MEDIA IN NETWORKS
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TRANSMISSION MEDIA IN NETWORK
Definition : Links that connect nodes
Choice impacts :
•Speed
•Security
•Size
Transmission
Media
Guided /
Wired
Twisted Pair
Coaxial
Unguided /
Wireless
Fiber Optic
Radio
Frequency
Microwave
Satellite
Infra-red
Twisted Pair (Kabel Pasangan Berlingkar)
• Is a type of wiring in which two conductor of a single circuit are
twisted together.
• Twisted pair cable falls into one of 2 type:
1. Unshielded Twisted Pair (UTP)
2. Shielded Twisted Pair (STP)
• Twisted pair cables are found in many Ethernet networks and
telephone system application.
• They are often grouped into sets of 25 pair according to a standard
25 pair color code originally developed by AT&T Corporation.
• Category : Standard EIA/TIA 568 set in the twisted pair cable
specifications for computer connectivity. EIA/TIA uses the term
category (Cat) to distinguish the type of cable used.
Twisted Pair Cabling Categories
Category
Data Rate
(Mbps)
Bandwidth
(MHz)
1
2
3
4
1
4
16
20
0.4
4
16
20
Voice only
4 Mbps token ring
10BaseT Ethernet
16 Mbps token ring
100 (2pair)
100
100BaseT Ethernet
1000 (4pair)
1000
1000
10000
10000
100
100
250
500
600
Gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet
10 Gigabit Ethernet
10 Gigabit Ethernet
5
5e
6
6a
7
Intended Use
• Connector : Register Jack RJ11 (Phone) and RJ45 (Ethernet)
• Installation : two standard code used in the installation of cable
EIA/TIA 568 A and EIA/TIA 568 B with two types of cable installation:
1. Straight-Through (Pemasangan Lurus)
2. Cross Over (Pemasangan Terbalik)
Coaxial Cable (Kabel Sepaksi)
• Coaxial cable looks similar to the cable used to carry TV signal. A
solid-core copper wire runs down the middle of the cable. Around
that solid-core copper wire is a layer of insulation, and covering that
insulation is braided wire and metal foil, which shields against
electromagnetic interference. A final layer of insulation covers the
braided wire.
• All types have been assigned an RG (Radio Guide) specification
number.
• The bandwidth for coaxial cable is 10 Mbps.
• Types (2):
1. Thinnet coaxial :
• is a flexible coaxial cable about ¼ inch thick.
• It’s used for short-distance and connects directly to a
workstation’s network adapter card using a British Naval
Connector (BNC).
• The maximum length of cable is 185 meters.
2. Thicknet coaxial :
• is thicker cable than thinnet.
• Thicknet cable is about ½ inch thick.
• Can support data transfer over longer distances than
thinnet.
• The a maximum cable length of 500 meters and usually is
used as a backbone to connect several smaller thinnetbased networks.
Fiber Optic (Kabel Gentian Kaca)
• Optical Fiber cables use optical fibers that carry digital data signals
in the form of modulated pulses of light (exceed 10Gbps)
• An optical fiber consists of an extremely thin cylinder of glass, called
the core, surrounded by a concentric layer of glass, known as the
cladding.
• There are two fibers per cable—one to transmit and one to receive.
The core also can be an optical-quality clear plastic, and the
cladding can be made up of gel that reflects signals back into the
fiber to reduce signal loss.
•There are two types of fiber optic cable:
1. Single Mode Fibre (SMF)
2. Multi Mode Fibre (MMF)
•Connector type (patch cord) are characterized by :
1. Low insertion loss (signal)
2. Good repeatability
3. Good interchange
4. Excellent environmental adaptability
3.2.2 : THE BENEFIT AND LIMITATIONS OF THE
NETWORKING MEDIA
1) FIBER OPTIC CABEL
THROUGHPUT
NOISE
IMMUNITY
SIZE
COST
Fiber has
proved
reliable in
transmitting
data at rates
that exceed
10 Gigabits
(or 10,000
Megabits)
per second.
Because fiber
does not
conduct
electrical
current to
transmit
signals,it is
unaffected by
EMI.
Depending
on the type
of fiber-optic
cable used,
segment
lengths from
150 to
40,000
meters.
Fiber-optic
cable is the
most
expensive
transmission
medium.
2) TWISTED PAIR CABLE (UTP AND STP)
THROUGHPUT
NOISE IMMUNITY
SIZE
COST
STP and UTP can
both transmit
data at 10, 100,
and 1000 Mbps
(1Gbps),
depending on the
grade of cabling
and the
transmission
method in use.
Because of its
shielding, STP is
more noiseresistant than
UTP.
The maximum
segment length
for both STP
and UTP is 100
m, or 328 feet.
STP is more
expensive than
UTP because it
contains more
materials and it
has a lower
demand.
3) Coaxial Cable
• Coaxial cables are a type of cable that is used by
cable TV and that is common for data
communications.
• Taking a round cross-section of the cable, one
would find a single center solid wire
symmetrically surrounded by a braided or foil
conductor. Between the center wire and foil is a
insulating dialectric. This dialectric has a large
affect on the fundamental characteristics of the
cable. In this lab, we show the how the
permittivity and permeability of the dialectric
contributes to the cable's inductance and
capacitance. Also, these values affect how quickly
electrical data is travels through the wire.
•
The radius of our cable's inner copper wire was 42mm and
there was 2.208mm of polyethylene between the inner wire
and outer mesh conductors.
Cabling building
 IT cables consist of a metal or fiber optic (glass)
core wrapped in a plastic sheath .
 These systems are usually separated into voice
and data sub-systems .
 Voice systems typically use twisted pair copper
cables for both vertical (riser) and horizontal
cables .
 Data systems commonly use fiber optics for
risers and copper for connecting PC’s to data
network hubs .
 cabling systems also include separate coaxial cables for video systems.
 The most common system for routing
cables in commercial buildings is placing
riser cable in sealed conduits that are
firestopped according to fire code
requirements.
 Horizontal cables are usually routed
through ceiling, wall and raised floor area
generally with metal conduits used
only
as
protective guides
behind
sheetrock walls.
Work Areas
The work area is the space inside a building
where employees, building occupants, or
system users work and use their
communication equipment.
This is also the area where the horizontal
communication cables are terminated.
Work area usually includes the user
communication equipment such as
computers, phones, modems, and data
terminals.
Work area locations can be placed in any
useable square footage in a building or
on a building floor. Careful consideration
must be given when planning locations in
a building.
Industry cabling standards also require
that a minimum of two approved media
types be installed to each location.
 Each outlet of connection must terminate
one approved type of horizontal media.
Therefore, each location must be supported
by a minimum of two modular
outlets/connectors and two approved
horizontal cables.
 Work area outlets can be placed in different
locations for each area. The exact location is
usually a function of the horizontal pathway
connecting the area to the Telecom Room
(TR). Work area outlet locations can be
installed in any of the following areas.
1. On the wall
2. On the floor
3. On a power pole
4. On the modular furniture
3.2.4 : Characteristic of
Wireless Transmission
Signal Propagation
• Reflection
The wave encounters an obstacle and reflects—or bounces
back—toward its source. A wireless signal will bounce off objects
whose dimensions are large compared to the signal’s average
wavelength.
• Diffraction
Wireless signal splits into secondary waves when it encounters an
obstruction. The secondary waves continue to propagate in the
direction in which they were split.
• Scattering
Reflection in multiple different directions of a signal. Scattering
occurs when a wireless signal encounters an object that has small
dimensions compared to the signal’s wavelength.
Signal Degradation
• Original signal issued by the transmitter will
experience fading or a change in signal
strength as a result of some of the
electromagnetic energy being scattered,
reflected, or diffracted after being issued by
the transmitter.
• the strength of the signal that reaches the
receiver is lower than the transmitted signal’s
strength.
• Interference can distort and weaken a wireless
signal and they are more vulnerable to noise.
Narrowband, Broadband And Spread
Spectrum Signal
• Narrowband
transmitter concentrates the signal energy at a
single frequency or in a very small range of
frequencies.
• Broadband
uses a relatively wide band of the wireless
spectrum. As a result of their wider frequency
bands, offer higher throughputs than
narrowband technologies.
• spread spectrum
The use of multiple frequencies to
transmit a signal.
• spread spectrum signaling is
called FHSS (frequency hopping
spread spectrum) & DSSS (direct
sequence spread spectrum).
FSHH
(frequency hopping spread spectrum)
• Signal jumps between several different
frequencies within a band in a synchronization
pattern known only to the channel’s receiver
and transmitter.
DSS
(direct sequence spread spectrum)
• signal’s bits are distributed over an entire
frequency band at once. Each bit is coded so
that the receiver can reassemble the original
signal upon receiving the bits.
Fixed And Mobile Wireless
Communication
• The operation of wireless devices or systems used
to connect two fixed locations (e.g., building to
building or tower to building) with a radio or other
wireless link, such as laser bridge. Usually, fixed
wireless is part of a wireless LAN infrastructure.
The purpose of a fixed wireless link is to enable
data communications between the two sites or
buildings. Fixed wireless data (FWD) links are often
a cost-effective alternative to leasing fiber or
installing cables between the buildings.
Mobile Wireless
• The receiver can be located anywhere
within the transmitter’s range. Allows
the receiver to roam from one place to
another while continuing to pick up its
signal.
Infrared
• Infrared (IR) light is electromagnetic radiation with
longer wavelengths than those of visible light,
extending from the nominal red edge of the visible
spectrum at 700 nm to 1 mm. This range of
wavelengths corresponds to a frequency range of
approximately 430 THz down to 300 GHz. Infrared
light is emitted or absorbed by molecules when they
change their rotational-vibrational movements.
• infrared transmission is most often used for
communications between devices in the same room.
• infrared signaling requires more power, travels
shorter distances, and transmission around obstacles
less successfully than the wireless technique.
Wireless LANs
• A wireless local area network (WLAN) links two or
more devices using some wireless distribution
method (typically spread-spectrum or OFDMradio),
and usually providing a connection through an
access point to the wider Internet. This gives users
the mobility to move around within a local coverage
area and still be connected to the network. Most
modern WLANs are based on IEEE 802.11 standards,
marketed under the Wi-Fi brand name. WLANs were
once called LAWNs (for local area wireless network)
by the Department of Defense.
 Smaller wireless networks, in which
a small number of nodes closely
positioned need to exchange data,
can be arranged in an ad hoc.
 In an ad hoc WLAN, wireless nodes,
or stations, transmit directly to each
other via wireless NICs without an
intervening connectivity device.
 WLANs can use the infrastructure mode,
which depends on an intervening
connectivity device called an access
point.
 AP (access point) is a device that accepts
wireless signals from multiple nodes and
retransmits them to the rest of the
network.
 Access point must have sufficient power
and be strategically placed so that
stations can communicate with it.
 Like other wireless devices, access points
contain an antenna connected to their
transceivers
An infrastructure WLAN
Wireless LAN interconnection
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