Wireless & Mobile Networks
Explore the principles of wireless communications, Wi-Fi standards (802.11), cellular network generations (4G/5G), and short-range technologies.
Introduction to Wireless Networks
Unlike wired networks that rely on physical cables, wireless networks use electromagnetic waves (typically radio waves or infrared) to transmit data through the air. This enables device mobility and eliminates cabling costs, but introduces challenges in security, interference, and range.
Wi-Fi Standards (IEEE 802.11)
Wi-Fi is a family of wireless network protocols based on the IEEE 802.11 standards. Over the years, these standards have evolved to offer higher speeds and better reliability:
- 802.11b (1999) — Operated on the 2.4 GHz band with speeds up to 11 Mbps.
- 802.11g (2003) — Kept the 2.4 GHz band but increased speed to 54 Mbps.
- 802.11n / Wi-Fi 4 (2009) — Added support for both 2.4 GHz and 5 GHz bands. Introduced MIMO (Multiple Input Multiple Output) antennas. Speeds up to 600 Mbps.
- 802.11ac / Wi-Fi 5 (2013) — Operated primarily on 5 GHz. Introduced MU-MIMO (Multi-User MIMO). Speeds up to 3.46 Gbps.
- 802.11ax / Wi-Fi 6 & 6E (2019) — Improved performance in crowded environments. Wi-Fi 6E added the clean 6 GHz band. Speeds up to 9.6 Gbps.
- 802.11be / Wi-Fi 7 (2024) — The latest standard, offering wider channels and speeds up to 46 Gbps for extreme low-latency performance.
Wi-Fi Frequency Bands
- 2.4 GHz band — Longer range and better wall penetration, but slower speeds and high interference (microwaves, baby monitors, Bluetooth use it).
- 5 GHz band — Faster speeds and less congestion, but shorter range and poorer wall penetration.
- 6 GHz band — Super-fast, ultra-low latency, and virtually no interference, but very short range and easily blocked by physical obstacles.
Cellular Networks (Generations)
Cellular networks divide geographic areas into "cells," each served by at least one fixed-location transceiver (cell tower):
- 1G (1980s) — Analog voice calls only.
- 2G (1990s) — Digital voice and basic text messaging (SMS).
- 3G (2000s) — Introduced mobile internet access, enabling web browsing and video calling.
- 4G LTE (2010s) — True mobile broadband. Designed for high-speed data, HD streaming, and IP-based voice calls.
- 5G (2020s) — Offers ultra-low latency (under 1ms) and massive device capacity. Uses millimeter waves to achieve gigabit speeds, powering IoT and autonomous driving.
Short-Range Wireless Technologies
- Bluetooth — Low-power, short-range (up to 10 meters) technology for connecting personal devices like headphones, keyboards, and smartwatches.
- NFC (Near Field Communication) — Extremely short-range (under 4 cm) security-focused technology used for contactless payments (Apple Pay, Google Pay) and data exchange.
- RFID (Radio Frequency Identification) — Uses electromagnetic fields to automatically identify and track tags attached to objects (e.g., inventory tracking, toll booth passes).
What's Next?
Learn how wireless data is protected from eavesdroppers in Network Security Basics, or explore how devices get connected automatically in Common Network Protocols.