Modern Wireless (WiFi 6, 6E, & 7)
Wireless has evolved from "Best Effort" to "Critical Infrastructure". New standards prioritize efficiency and low latency over just raw speed.
1. The Generations Cheat Sheet
| Name | Standard | Key Feature | Max Speed (Theoretical) |
|---|---|---|---|
| WiFi 5 | 802.11ac | 5GHz only. MU-MIMO (Downlink only). | 3.5 Gbps |
| WiFi 6 | 802.11ax | OFDMA (Efficiency). Target Wake Time (IoT battery life). BSS Coloring. | 9.6 Gbps |
| WiFi 6E | 802.11ax | Adds 6 GHz Band (Massive new spectrum). No legacy devices allowed. | 9.6 Gbps |
| WiFi 7 | 802.11be | MLO (Multi-Link Operation). 320 MHz channels. 4K-QAM. | 46 Gbps |
Engineer's Notebook: OFDMA vs OFDM
OFDM (WiFi 5): Like a delivery truck that can only carry one package at a time. If the package is small, the rest of the truck is empty (wasted airtime).
OFDMA (WiFi 6): Subdivides the truck (channel) into smaller "Resource Units" (RUs). It can carry packages for multiple users simultaneously in a single transmission. Huge win for high-density venues (stadiums, airports).
2. Spectrum: The Real Constraint
Speed depends on channel width (20, 40, 80, 160 MHz). But wider channels need more contiguous spectrum.
- 2.4 GHz: "Junk band". Only 3 non-overlapping channels (1, 6, 11). Crowded by microwaves, Bluetooth, and neighbors.
- 5 GHz: The workhorse. 25 channels (if you use DFS). Good balance of range and speed.
- 6 GHz: The superhighway. 1200 MHz of clean spectrum. No legacy devices allowed (WiFi 5 devices literally cannot see this band). This means zero interference from old tech.
3. WPA3: Fixing the Cracks
WPA2 (2004) served us well, but it was vulnerable to offline dictionary attacks (KRACK).
- SAE (Simultaneous Authentication of Equals): Replaces the 4-way handshake PSK exchange. Even if an attacker captures the handshake, they cannot crack the password offline.
- OWE (Opportunistic Wireless Encryption): Encrypts "Open" (Guest) networks automatically without a password. No more sniffing traffic at coffee shops.
- 192-bit Security: Required for WPA3-Enterprise (Government/Defense grade).
References
- IEEE 802.11ax (WiFi 6) - High Efficiency Wireless LAN (HEW).
- IEEE 802.11be (WiFi 7) - Extremely High Throughput (EHT).
- Wi-Fi Alliance WPA3 Specification - Security standard using Dragonfly Key Exchange (SAE).