l1

Lecture 1: Wireless Networking Overview

Introduction

Wireless communication is the transmission of information over a distance
without physical cables, using electromagnetic waves (radio, microwave, infrared).

Challenges

Interference: Signals disrupting each other.
Limited Bandwidth: Frequency spectrum is a finite resource.
Security: Data is vulnerable to interception (eavesdropping).
Signal Fading: Obstacles (walls/buildings) weaken the signal.
Energy Consumption: Mobile devices must balance performance with battery life.

How it Works (The Process)

Encoding: Data $\to$ Electrical Signal.
Modulation: Signal + Carrier Wave ( $f_{c}$ ).
Transmission: Via Antennas.
Propagation: Signal travels through space (reflection, scattering, diffraction).
Reception/Demodulation: Receiver captures signal and extracts data.

Key Technologies & Standards

Wireless Sensors (IEEE 802.15.4)

Frequency: $2.4 to 2.4835 GHz$
Data Rate: $250 kbps$
Power: $- 24 dBm to 0 dBm$
Sensitivity: $- 90 to - 94 dBm$
Range: $50 m$ (indoors), $125 m$ (outdoors)

RFID (Radio-Frequency Identification)

Frequency: $13.56 MHz$ (ISO14443-A/B)
Distance: $\approx 1 cm$
Speed: up to $848 kbps$

Spectrum & Frequency Ranges

Wireless communication primarily uses the Radio and Microwave spectrum.

Band	Frequency Range	Wavelength ( $λ$ )
VLF	$< 30 kHz$
LF	$30 - 300 kHz$
MF	$300 kHz - 3 MHz$	$\approx 100 m$ (at $1 MHz$ )
HF	$3 - 30 MHz$
VHF	$30 - 300 MHz$	$\approx 1 m$ (at $100 MHz$ )
UHF	$300 MHz - 3 GHz$
SHF	$3 - 30 GHz$	$\approx 1 cm$ (at $10 GHz$ )
EHF	$> 30 GHz$

Protocol Layer Model

Application: Services, location, multimedia.
Transport: Flow control, QoS.
Network: Addressing, routing, hand-over.
Data Link: Authentication, MAC, multiplexing.
Physical: Encryption, modulation, interference, frequency.

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