PRESENTATION ON TRANSMISSION MEDIA

TRANSMISSION MEDIATHE TRANSMISSION MEDIUM IS THE PHYSICAL PATH BY WHICH A MESSAGE TRAVELS FROM SENDER TO RECEIVER.

COMPUTERS AND TELECOMMUNICATION DEVICES USE SIGNALS TO REPRESENT DATA.

THESE SIGNALS ARE TRANSMITTED FROM A DEVICE TO ANOTHER IN THE FORM OF ELECTROMAGNETIC ENERGY.

CLASSES OF TRANSMISSION MEDIA

GUIDED MEDIA AND ITS TYPES:

Consists of physical connection between source and destination via a wire or a cable.

There are three basic types of guided media :

• Twisted pair cable

• Co-axial cable

• Fiber-optic cable

TWISTED PAIR CABLE

Consists of two copper wires insulated from each other by plastic.

The twisting helps to reduce the interference (noise) and crosstalk.

Low frequency transmission medium

TYPES OF TWISTED PAIR CABLE

STP (shielded twisted pair)

the pair is wrapped with metallic foil or braid to insulate the pair from electromagnetic interference

UTP (unshielded twisted pair)

each wire is insulated with plastic wrap, but the pair is encased in an outer covering

ADVANTAGES AND DISADVANTAGES OF TWISTED PAIR:

Advantages: Inexpensive and readily available

Flexible and light weight

Easy to work with and install

Disadvantages: Susceptibility to interference and noise Attenuation problem

• For analog, repeaters needed every 5-6km

• For digital, repeaters needed every 2-3km

Relatively low bandwidth (3000Hz)

COAXIAL CABLE (OR COAX):

Used for cable television, LANs, telephony Has an inner conductor surrounded by a braided mesh Both conductors share a common center axial, hence the

term “co-axial”

ADVANTAGES AND DISADVANTAGES OF COAXIAL CABLE:

Advantages: Higher bandwidth Can be tapped easily Much less susceptible to interference than twisted pair

Disadvantages:

High attenuation rate makes it expensive over long distance

Bulky

FIBER OPTIC

• These are similar to coaxial cable. It uses electric signals to transmit data. At the centre is the glass core through which light propagates.

• Fiber optic cable has bandwidth more than 2 gbps (Gigabytes per Second)

ADVANTAGES :

• Speed of transmission

• Noise control

• Used for analog and digital signals

• Long distance transmission

• Low data loss

DISADVANTAGES :

• High price

• Difficult to install

• Expensive in maintenance

UNBOUNDED TRANSMISSION MEDIA

WHAT IS UNBOUNDED TRANSMISSION MEDIA?

• Unlabelled media of transmission of data

• Unguided or wireless media sends the data through air (or water)

• Use of antenna for transmission of signal

WHY DO WE USE UNBOUNDED TRANSMISSION MEDIA

• High-Frequency Radiotelephone

• Microwave Radio

• Satellite Radio link Systems

• Commercial Satellites

EXAMPLES OF UNBOUNDED TRANSMISSION MEDIA

• Microwave

• Radio waves

• Infrared waves

• Satellites

RADIO WAVE• Signals are sent by modulation of electromagnetic waves with frequencies

below those of visible light

ADVANTAGES :

• carry a message instantaneously over a wide area.

• Cheaper(message are sent through air)

• Simple in transmission

DISADVANTAGES

• Travel in a straight line, so repeater stations may be needed

• The range of frequencies that can be accessed by existing technology is limited

• Competition among companies to get the frequency

MICROWAVE• the transmission of information or energy by electromagnetic

waves whose wavelengths are conveniently measured in small numbers of centimeter.

• radio spectrum ranges across frequencies of roughly 1.0 gigahertz (GHz) to 300 GHz.

• requires line of sight in order to work properly• to allow two way communications two frequencies are

used(that doesn’t mean it requires two antenna)• to increase this coverage each antenna has a built-in repeater

that regenerates the signal before passing it on to the next antenna in line

OPERATING FREQUENCIES

PRINCIPLE

• Use of radio frequency to achieve the transmissions (operating between 1Ghz to 170Ghz)

• Clear line-of-sight with no obstacles in the way• Regular relay stations required due to line of site and cost

considerations

ADVANTAGES AND DISADVANTAGES

Advanatages• No cables needed• Multiple channels available• Wide bandwidth

Disadvantages• Line-of-sight will be disrupted if any obstacle, such as new buildings, are in

the way• Signal absorption by the atmosphere. Microwaves suffer from attenuation

due to atmospheric conditions.• Towers are expensive to build

BLUETOOTH

• It is an always on, low power, short ranged radio link for communication between mobile devices

• Developed in 1994 by the Swedish company Ericsson to enable laptops make calls over mobile phones

• Also known as 802.15, it employs the 2.4 GHz unlicensed band, the same as 802.11b wireless, but does not interfere with it

• Provides data rates of up to 720 Kbps• Power output is around 1 milliwatt, compared to the average cell

phone’s 500 milliwatt power output

BLUETOOTH CHARACTERISTICS

• Allows up to 8 devices to communicate in a local network called a Piconet,

• Because of its low power consumption, its range is limited to 10 m.

• However, range can be increased to 100 m by employing a scatternet topology or a higher powered Antenna

• Three classes of Bluetooth devices

• Class 1 – 100 m = 20 dBm power

• Class 2 – 10m = 4 dBm power

• Class 3 – 10 cm @ 0 dBm power

BLUETOOTH DEVICES

• Bluetooth exists in many products, such as telephones, tablets, media players, robotics systems, handheld, laptops and console gaming equipment, and some high definition headsets, modems, and watches.

APPLICATIONS

• A typical Bluetooth mobile phone headset.

• Wireless control of and communication between a mobile phone and a handsfree headset. This was one of the earliest applications to become popular.

• Wireless control of and communication between a mobile phone and a Bluetooth compatible car stereo system.

• Wireless control of and communication with tablets and speakers such as iOS and Android devices.

• Wireless Bluetooth headset and Intercom. Idiomatically, a headset is sometimes called "a Bluetooth".

WIMAX

• Worldwide Interoperability for Microwave Access (WiMAX)• One of the hottest broadband wireless technologies around today.• Broadband wireless is a technology that promises high-speed

connection over the air. • Based on IEEE 802.16 specification

A WiMAX system consists of two parts:

• A WiMAX tower, similar in concept to a cell-phone tower(can provide coverage to a very large area as ~8,000 square km).

• A WiMAX receiver - The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today.

APPLICATIONS

• Providing portable mobile broadband connectivity across cities and countries through a variety of devices.

• Providing a wireless alternative to cable and digital subscriber line (DSL) for "last mile" broadband access.

• Providing data, telecommunications (VoIP) and IPTV services (triple play).

• Providing a source of Internet connectivity as part of a business continuity plan

FEATURES• Very high peak data rates

• Scalable bandwidth and data rate support

• Adaptive modulation and coding (AMC)

• Flexible and dynamic per user resource allocation

• Quality-of-service support

• Robust security