16.3 Wireless Technologies and Standards - optional

16.3 Wireless Technologies and Standards

Overview of Wireless Technologies

  • IoT Growth: Wireless technology is increasingly important as it connects devices for everything from smart homes to healthcare.

  • WLANs: Widely used for personal and enterprise networks, enabling mobile communication and internet access.

Wireless Standards

  1. IEEE 802.11: The foundational standard for wireless LANs (WLAN).

  2. 802.11a/b/g: Older standards with varying speeds and frequencies.

  3. 802.11n: Introduced in 2009 with support for MIMO (multiple-input, multiple-output) and faster speeds.

  4. 802.11ac: Introduced in 2013, supports wider channels, more spatial streams, and improved data rates.

Key Features of 802.11ac

  • Wider Channel Width: Up to 160 MHz for faster speeds.

  • MU-MIMO: Multi-user, multiple input, multiple output, which allows multiple devices to receive data simultaneously.

  • QAM-256 Modulation: Improved modulation for faster data transfer.

  • Maximum Speeds: 802.11ac can achieve speeds up to 1 Gbps, much faster than previous standards.

Radio Frequencies

  • ISM Band: Widely used for Wi-Fi, operating at 2.4 GHz and 5 GHz, although crowded.

  • 5 GHz Band: Less congested and provides faster speeds but shorter range.

CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)

  • Why not CSMA/CD?: Wireless networks can’t detect collisions as easily, so CSMA/CA is used to avoid them by listening for clear channels before transmitting.

MIMO (Multiple-Input, Multiple-Output) Technology

  • MIMO improves throughput by using multiple antennas for transmitting and receiving data.