Wireless Networking
Overview
Wireless networking enables communication without physical cables, using radio waves, microwaves, or infrared signals. This section covers WiFi, 5G, and modern network paradigms like SDN and NFV.
Wireless Technologies
graph TD
A[Wireless Technologies] --> B[Short Range]
A --> C[Medium Range]
A --> D[Long Range]
A --> E[Cellular]
B --> F[Bluetooth 5.3m]
B --> G[NFC 0.1m]
B --> H[Zigbee 100m]
C --> I[WiFi 100m+]
D --> J[WiMAX 50km]
D --> K[Satellite]
E --> L[4G LTE]
E --> M[5G NR]
Frequency Bands
| Band | Frequency | Range | Use |
|---|---|---|---|
| Sub-1 GHz | 900 MHz | Long | IoT, rural |
| 2.4 GHz | 2.4-2.4835 GHz | Medium | WiFi, Bluetooth |
| 5 GHz | 5.15-5.825 GHz | Short | WiFi (less interference) |
| 6 GHz | 5.925-7.125 GHz | Short | WiFi 6E |
| mmWave | 24-100 GHz | Very short | 5G, high bandwidth |
Key Wireless Concepts
| Concept | Description |
|---|---|
| SSID | Network name (Service Set Identifier) |
| BSS | Basic Service Set (one AP + connected clients) |
| ESS | Extended Service Set (multiple APs, same SSID) |
| Roaming | Moving between APs seamlessly |
| MIMO | Multiple-Input Multiple-Output (antenna arrays) |
| OFDMA | Orthogonal Frequency Division Multiple Access |
| Beamforming | Directing signal toward specific clients |
| CSMA/CA | Carrier Sense Multiple Access with Collision Avoidance |
Interview Questions
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Q: What’s the difference between 2.4 GHz and 5 GHz WiFi? A: 2.4 GHz has longer range and better wall penetration but more interference (only 3 non-overlapping channels). 5 GHz has shorter range but more channels (24+) and less interference. 6 GHz (WiFi 6E) adds even more channels.
-
Q: What is SDN? A: Software-Defined Networking separates the control plane (routing decisions) from the data plane (packet forwarding). A central controller manages network devices programmatically. See SDN.
-
Q: What is NFV? A: Network Function Virtualization replaces dedicated hardware (firewalls, load balancers) with software running on commodity servers. See NFV.
Summary
Wireless networking spans from short-range (Bluetooth) to cellular (5G). WiFi, 5G, SDN, and NFV are the key topics for interviews. Understanding frequency bands, modulation, and modern network architectures is essential.