1. Unit I: Introduction

2. TOPICS Fundamentals of Wireless Communication Technology
The Electromagnetic Spectrum
Radio propagation Mechanisms
Characteristics of the Wireless Channel
MANETs and WSNs concepts and architectures
Applications of Ad Hoc and Sensor networks
Design Challenges in Ad hoc and Sensor Networks.

3. Fundamentals of Wireless Communication Technology
Transmitting/receiving voice and data using electromagnetic waves in open space.
Information from sender to receiver is carried over a well defined channel.

4. Fundamentals of Wireless Communication Technology
Each channel has a fixed frequency bandwidth & capacity (bit rate).
Different channels can be used to transmit information in parallel and independently.

5. Electromagnetic Spectrum
X rays and gamma rays are not used due to practical concerns
Radio waves are easy to generate and most widely used.

6. Electromagnetic Spectrum
Band Name
Frequency
Wavelength
Application
Extremely Low Frequency (ELF)
30 – 300 Hz
10,000 – 1000 Km
Power line frequencies
Voice Frequency (VF)
300 – 3,000 Hz
1,000 – 100 Km
Telephone communication
Very Low Frequency (VLF)
3 – 30 KHz
100 – 10 Km
Marine communication
Low Frequency (LF)
30 – 300 KHz
10 – 1 Km
Medium Frequency (MF)
300 – 3000 KHz
1000 – 100 m
AM broadcasting
High Frequency (HF)
3 – 30 MHz
100 – 10 m
Long distance aircraft/ship communication
Very High Frequency (VHF)
30 – 300 MHz
10 – 1 m
FM broadcasting
Ultra High Frequency (UHF)
300 – 3000 MHz
100 – 10 cm
Cellular telephone
Super High Frequency (SHF)
3 – 30 GHz
10 – 1 cm
Satellite communication, Microwave links
Extremely High Frequency (EHF)
30 – 300 GHz
10 – 1 mm
Wireless local loop

7. Electromagnetic Spectrum
VLF, LF, MF bands – ground waves or surface waves
SHF band – space wave
VHF band – sky wave

8. Radio Propagation mechanism
Reflection – dimension of an object is larger than wavelength of radio wave
Scattering – dimension of an object is smaller than wavelength of radio wave
Diffraction – dimension of an object is comparable to the wavelength of radio wave

9. Characteristics of the wireless channels
Path loss
Fading
Interference
Doppler shift

10. Path loss
Ratio of power of the transmitted signal to the power of same signal received by receiver.
Dependent on radio frequency used and nature of terrain
Path loss models – Free space & Two ray
Free space – no attenuation of signals, only direct path
Pr = Pt Gt Gr (/4πd)2
Two ray – direct path & Reflected path
Pr = Pt Gt Gr (ht hr/d2)2

11. Fading Fluctuations in signal strength when received at the receiver.
Types – (1) Fast/small scale fading (2) slow/large scale fading.
Fast fading – rapid fluctuations in amplitude, phase or multipath delays.
Slow fading – objects partially absorb the transmissions
Counter measure – Diversity & Adaptive modulation

12. Interference Types : (1) ACI (2) CCI (3) ISI Interference
Counter measure
ACI
Guard band
CCI
Usage of directional antennas, dynamic channel allocation
ISI
Adaptive equalization

13. Doppler Shift
Change in frequency when transmitter and receiver are mobile in nature.
Higher frequency – when both move towards
Lower frequency – when both move away

14. Applications of Ad hoc Networks
Military applications (Secure & Cost)
Communication among group of soldiers
Communication among military objects (fleets of air planes or warships)
Collaborative & Distributed computing (Reliability & Economic)
Communication among group of people in conference
Emergency operations
Search & rescue, crowd control and commando operations
Wireless mesh networks (Self organization & maintenance)
Residential zones
Highways
Business zones
Civilian regions
University campuses
Wireless sensor networks
Hybrid wireless networks