Engineering Subject - Mobile computing and wireless Communication related

1. ACTIVE LEARNING
ASSIGNMENT FOR THE
SUBJECT
“MOBILE COMPUTING
&
WIRELESS COMMUNICATION”
Channel Capacity & Transmission Media
Guided By : -
Keyur N. Upadhyay
Prepared By :-
Hemant H. Chetwani
(130410107010 LY CE-II)

2. Channel ?
It is a communication
path through which
data or information
can be send from one
node to another
node.

3. Channel Capacity
• Maximum rate at which data can be transmitted over a communication
path or channel is called channel capacity.
• The channel capacity depends on four factors:
1. DATA RATE (in bps)
2. BANDWIDTH (in Hz)
3. NOISE (in dB)
4. ERROR RATE (in %)
• Bandwidth is proportional to cost, for digital data, it is desirable to get data
rate as high as possible within a limit of error rate for a given bandwidth.

4. Nyquist Bandwidth
• If the rate of signal transmission is 2B, then signal with frequencies no
greater than B is sufficient to carry signal rate.
• For the given bandwidth B, the highest possible signal rate is 2B.
• For the given binary signal, data rate supported by B Hz is 2B bps
• Data rate can be increased by increasing the number of different signal
elements.(using M signal levels)
• C= 2B log2M
Where, M is the number of signal elements or
voltage levels

5. Shannon Capacity Formula
• Nyquist formula gives the relationship between bandwidth and data rate.
• At given noise level,
• Shorter bits imply more bits corrupted.
• High data rate means higher error rate.
• Shannon formula gives the maximum possible capacity.
C (in bps) = B log2 (1+SNR)
Where, SNR is Signal-to-Noise Ratio.

6. Signal-to-Noise (SNR) Ratio
• SNR is defined as ratio of power in signal to the power in noise present at a
particular point in the noise.
• SNR is typically measured at the receiver to process the signal and
eliminate unwanted noise.
SNRdB = 10 log10 (Signal / Noise)
• SNR expresses the amount by which the intended signal exceeds the noise
level.
• SNR sets the upper bound on achievable data rate.
• High SNR means high quality signal & Low SNR means signal needs
repeaters.

7. Transmission Media
• A transmission medium is a material substance that can propagate energy
waves. (Data is transmitted normally through electrical or electromagnetic
signals.)
• Basically, it is the path between transmitter and receiver.Transmission
media is also called Communication Channel.
• The transmission media that are used to convey information can be
classified as Guided or Unguided.
• Guided media provides physical path along which the signals are
propagated through wires or cables.
• Unguided media employ antenna for transmitting through air, vacuum, or
water.

8. Classification ofTransmission Media
Transmission
Media
Guided/
Wired
Twisted
Pair
Coaxial
Cable
Optical
Fibers
Unguided/
Wireless
Radio
Waves
Infrared Microwave

9. GUIDED/WIRED
Guided media provides physical path along which the signals are
propagated through wires or cables.

10. Twisted Pair
• Separately insulated.
• Twisted together.
• Often “bundled “ into cables.
• Usually installed into building during construction.

11. Twisted Pair - Applications
• Most common medium.
• Telephone network.
• Between house and local exchange. (subscriber loop)
• Within buildings.
• To private branch exchange. (PBX)
• For local area networks. (LAN)
• 10Mbps or 100Mbps.

12. Coaxial Cable

13. Coaxial Cable Applications
• Most versatile medium.
• Television distribution.
• Ariel toTV.
• CableTV.
• Long distance telephone transmission.
• Can carry 10,000 voice calls simultaneously.
• Short distance computer systems links.
• Local area networks.

14. Optical Fiber

15. Optical Fiber - Benefits
• Greater capacity.
• Data rates of hundreds of Gbps.
• Smaller size & weight.
• Lower attenuation.
• Electromagnetic isolation.
• Greater repeater spacing.
• 10s of km at least.

16. UNGUIDED/WIRELESS
Unguided media employ antenna for transmitting through air,
vacuum, or water.

17. RadioWaves
• Wireless transmission of electrical waves.
• Includes FM and AM radio bands.
• Microwave is also a from of radio transmission.

18. InfraredWaves
• Invisible light waves whose frequency is below that of red light.
• Requires line of sight and are generally subject to interference from rain.
• Used in remote control units.

19. Microwave
• High frequency form of radio with extremely short wavelength.
(1cm to 1m)
• Often used for long distance.
• Terrestrial transmissions and cellular telephones.
• Requires line-of-sight.

20. Types of Microwave
Terrestrial Microwave Satellite Microwave

21. Types of Microwave
Microwave transmission has 2 types.
• A primary use for TERRESTRIAL microwave systems is in long-
haul communication, as an alternative to coaxial cable or optical
fiber.
• A communication SATELLITE is a microwave rely station used
to link two or more ground-based microwave earth stations or
ground stations.

22. Summary
• Channel Capacity can be measured by Nyquist Bandwidth formula or
Shannon Capacity formula.
• Nyquist formula gives the relationship between bandwidth and data rate,
while Shannon formula gives the maximum possible capacity.
Transmission media,
• Guided – wire.
• Unguided – wireless.
• For guided, the medium is more important.
• For unguided, the bandwidth produced by the antenna is more important.