This document provides an introduction to radio frequency (RF) parameters and considerations for telecommunications. It discusses the three main RF parameters that define radio frequency: over-the-air data rate, receive sensitivity, and transmit power. It also covers other factors like antenna selection, modulation techniques, and barriers to future growth like spectrum limitations. The document then introduces microwave communication and its advantages over radio waves. Finally, it discusses satellite communication, describing orbits, propagation delays, frequency bands, and common multiple access protocols.

1. I.C.T
INTRODUCTION TO TELECOMMUNICATION

2. CHAPTER 02
INTRODUCTION TO TELECOMMUNICATION
TELECOMMUNICATIONS
TERMINOLOGY

3. CHAPTER 02
INTRODUCTION TO TELECOMMUNICATION
2.1 RADIO FREQUENCY (RF)

4. Agenda
 Introduction to wireless communications
 Wireless link implications
 Medium: the radio spectrum
 The three main parameters that define radio–frequency:
 Over-the-air data rate
 Receive Sensitivity
 Transmit power
 Other Considerations
 Barriers to Future Growth

5. Introduction
 Wireless Communication System: Any electrical communication
system that uses a naturally occurring communication channel,
such as air, water, earth.
 Examples:
 Sonar
 Broadcast: Radio, TV, pagers, satellite TV, etc.
 Two Way: walkie talkie, cell phones, satellite phones,
 Wireless Local Area Networks, etc.

6. Wireless link implications
 Communications channel is natural (air)
 Medium regulated by governments
 frequency allocation, licensing, etc.
 Security issues

7. Medium: the radio spectrum
 Wireless communications use the electromagnetic
spectrum, which is regulated by government
institutions such as the Federal Communications
Commission (FCC) in USA.

8. Electromagnetic

9. Electromagnetic

10. RF CONSIDERATIONS
 The three main parameters that define radio–
frequency:
 Over-the-air data rate
 Receive Sensitivity
 Transmit power
 Range is a result of these three RF parameters and can be used to define
them

11. RF CONSIDERATIONS
 Transmit power
It is usually driven by regulatory and
power-consumptions considerations
For example, FCC allows up to 1 W of transmit
power in the United States in the 2.4 Ghz band

12. Other Considerations
 Antenna Selection
 Directionality
 Omni (360 degree coverage) directional
 Directional (limited range of coverage)
 Gain
 More gain means more coverage
 Polarization

13. Other Considerations
 Modulation Techniques
 Amplitude Shift Keying (ASK):
 very simple
 low bandwidth requirements
 very susceptible to interference
 Frequency Shift Keying (FSK):
 needs larger bandwidth
 Phase Shift Keying (PSK):
 more complex
 robust against interference
1 0 1
t
1 0 1
t
1 0 1
t

14. Range Depends On...
 Frequency
 Transmit power
 Radio sensitivity
 Processing gain from access technique and
redundancy
 Interference effects

15. Barriers to Future Growth
 Irreducible size of antennas
 Rising level of RF emissions -
interference problems and safety concerns
 Finite spectrum
 Lack of standards and interoperability of hardware

16. MICROWAVE
COMMUNICATION

17. Microwaves
 microwaves - electromagnetic waves with a frequency
between 1GHz and 1000 GHz
 microwaves frequency are further categorized into
frequency bands group.
 receivers need an unobstructed view of the sender to
successfully receive microwaves
 microwaves are ideal when large areas need to be
covered and there are no obstacles in the path

18. Electromagnetic

21. Advantages of microwaves over radio waves
 because of high frequency, more data can be sent through
microwaves -> increased bandwidth, higher speeds
 because of their short wave length, microwaves use smaller
antennas
 smaller antennas produce a more focused beam which is
difficult to intercept

22. Disadvantages of microwave communication
 they require no obstacle is present in the transmission path
 the cost of implementing the communication infrastructure is
high
 microwaves are susceptible to rain, snow, electromagnetic
interference

23. Microwaves usages
 carrier waves in satellite communications
 cellular communication
 wireless local area network
 GPS (Global Positioning System)

24. Microwave propagation modes
 microwaves, one generated, propagate in a straight line in
all directions
 there are 3 modes of propagation possible, and the mode
is decided based on distance and terrain:

25. Microwave signal attenuation

26. SATELLITE
COMMUNICATION

27. Overview
 Satellite is a microwave repeater in the space.
 There are about 750 satellite in the space, most
of them are used for communication.
 They are:
 Wide area coverage of the earth’s surface.
 Transmission delay is about 0.3 sec.
 Transmission cost is independent of distance.

28.  Satellite up links and down links can operate in different
frequency bands:
 The up-link is a highly directional, point to point link
 The down-link can have a footprint providing coverage for a substantial area "spot
beam“.
Band Up-Link (Ghz) Down-link (Ghz) ISSUES
C 4 6 Interference with ground links.
Ku 11 14 Attenuation due to rain
Ka 20 30 High Equipment cost

29. Orbits:
 LEO: Low Earth Orbit.
 MEO: Medium Earth Orbit
 GEO: Geostationary Earth Orbit

30.  At the Geostationary orbit the satellite covers
42.2% of the earth’s surface.
 Theoretically 3 geostaionary satellites provides
100% earth coverage

31. MAC(Media Access Control)
protocols for satellite links
 ALOHA:
 Every station can transmit any time
 Very low efficiency 18- 36 %.
 FDMA (Frequency Division Multiple Access)
 It is the oldest and most common.
 the available satellite channel bandwidth is broken
into frequency bands for different earth stations.

32.  TDMA (Time Division Multiple Access)
 channels are time multiplexed sequentially
 Each earth station gets to transmit in a fixed time slot
only.
 More than one time slot can be assigned to stations with
more bandwidth requirements.
 Requires time synchronization between the Earth
Stations.
 CDMA : (Code Division Multiple Access)
 Combination of time/frequency multiplexing
( a form of spread spectrum modulation).
 It provides a decentralized way of providing separate
channels without timing synchronization. It is a
relatively new scheme but is expected to be more
common in future satellites.

33. VSAT Network
 At the Very Small Aperture Terminal a lower performance
microwave transceiver and lower gain dish antenna
(smaller size) is used.
 VSAT networks are arranged in a star based topology.
 Ideal for centralized networks with a central host (Banking
institutions with branches all over the country).
 Use the S-ALOHA and TDMA

36. THANK YOU FOR YOUR TIME