Fundamental Principle of the Physical Layer
Move data in the form of electromagnetic signals across a transmission medium.
Signal
- A function that represents the variation of a physical quantity with respect to time
- Analog Signal and Digital Signal
Analog Signal
- All real-life signals are analog in nature
- Can take any value in the defined range
Digital Signal
- Can take only finite values at any given time
- Discretizes both time and magnitude
Media, Physical Components, and Signals
| Media | Physical Components | Signal |
|---|---|---|
| Copper Cable, Wired | UTP/STP, Coaxial, Connectors, NICs, Ports or Interfaces | Electromagnetic Signal |
| Fiber Optic Cable, Wired | Single-mode Fiber, Multimode Fiber, Connectors, NICs and Interfaces, Lasers and LEDs | A light pulse equals 1. No light pulse is 0 |
| Wireless Media | Access Points, NICs, Radio, Antennae | Radio waves |
Wireless Technologies
Wi-Fi
- IEEE 802.11 standards
- Commonly referred to as Wi-Fi
- Uses CSMA/CA
- Variations include:
- 802.11a: 54 Mbps, 5 GHz
- 802.11b: 11 Mbps, 2.4 GHz
- 802.11g: 54 Mbps, 2.4 GHz
- 802.11n: 600 Mbps, 2.4 and 5 GHz
- 802.11ac: 1 Gbps, 5 GHz
- 802.11ad: 7 Gbps, 2.4 GHz, 5 GHz, and 60 GHz
Bluetooth
- IEEE 802.15 standard
- Supports speeds up to 3 Mb/s
- Provides device pairing over distances from 1 to 100 meters
WiMAX
- IEEE 802.16 standard
- Provides speeds up to 1 Gbps
- Uses a point-to-multipoint topology to provide wireless broadband access