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Wi-Fi Complete Series · Part 1 of 6 WLAN Basics — What is Wireless LAN?History, how it works, IEEE 802.11 standard and real-world deployment scenarios IEEE 802.11 · CSMA/CA · IBSS / BSS / ESS · Frequency Bands · B2B Scenarios |
What is WLAN / Wi-Fi?
WLAN stands for Wireless Local Area Network — a local network that transmits data via radio signals rather than copper cables. In everyday speech, WLAN and Wi-Fi are used interchangeably, although Wi-Fi is technically a brand name of the Wi-Fi Alliance for certified IEEE 802.11-compliant devices.
The technical foundation is the IEEE 802.11 standard, maintained by the IEEE (Institute of Electrical and Electronics Engineers). It defines both the physical layer (PHY) and the Media Access Control (MAC) layer for wireless networks.
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✓ Advantages of WLAN No cabling required Flexible device placement Easy to extend Mobility within buildings Fast commissioning |
⚠ Limitations Susceptible to interference Shared medium Variable signal strength Higher latency than cable Security risks if misconfigured |
► Cable vs. WLAN (B2B) Cable: maximum stability WLAN: where cable is impractical Combination (WLAN + LAN) is optimal Industrial WLAN: 802.11-specific Always plan coverage upfront |
History & Milestones
| Year | Milestone |
| 1997 | First IEEE 802.11 standard published (2 Mbit/s) |
| 1999 | 802.11a (54 Mbit/s, 5 GHz) and 802.11b (11 Mbit/s, 2.4 GHz); Wi-Fi Alliance founded |
| 2003 | 802.11g (54 Mbit/s, 2.4 GHz) — backward compatible with 802.11b |
| 2009 | 802.11n (Wi-Fi 4): up to 600 Mbit/s, MIMO, dual-band |
| 2013 | 802.11ac (Wi-Fi 5): up to 3.5 Gbit/s, MU-MIMO, 5 GHz only |
| 2021 | 802.11ax (Wi-Fi 6/6E): up to 9.6 Gbit/s, OFDMA, new 6 GHz band |
| 2024 | 802.11be (Wi-Fi 7): up to 46 Gbit/s, Multi-Link Operation (MLO) |
How WLAN Works: CSMA/CA
WLAN is a shared medium: all devices in a radio cell share the same frequency. To avoid collisions, IEEE 802.11 uses CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) rather than the collision detection (CSMA/CD) used by Ethernet.
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CSMA/CA Process: 1. Is the channel clear? → Wait (DIFS) 2. Choose a random backoff time 3. Channel still clear? → Transmit 4. Expect ACK from receiver 5. No ACK → Retry |
Key MAC Terms: SSID: Network name (up to 32 characters) BSSID: MAC address of the access point Beacon Frame: Regular AP broadcast packets Association: Client↔AP connection setup Roaming: Switching between APs |
The IEEE 802.11 Standard Family
IEEE 802.11 is not a single standard but a whole family of amendments continuously developed by the IEEE 802.11 Working Group. The most important amendments:
| Amendment | Wi-Fi Gen. | Band | Max. Gross Rate | Year |
| 802.11b | Wi-Fi 1 | 2.4 GHz | 11 Mbit/s | 1999 |
| 802.11a | Wi-Fi 2 | 5 GHz | 54 Mbit/s | 1999 |
| 802.11g | Wi-Fi 3 | 2.4 GHz | 54 Mbit/s | 2003 |
| 802.11n | Wi-Fi 4 | 2.4 / 5 GHz | 600 Mbit/s | 2009 |
| 802.11ac | Wi-Fi 5 | 5 GHz | 3,500 Mbit/s | 2013 |
| 802.11ax | Wi-Fi 6/6E | 2.4 / 5 / 6 GHz | 9,600 Mbit/s | 2021 |
| 802.11be | Wi-Fi 7 | 2.4 / 5 / 6 GHz | 46,000 Mbit/s | 2024 |
Source: IEEE 802.11 Working Group · Full generation comparison: Part 2 of this series → Wi-Fi Standards
Topologies: IBSS, BSS and ESS
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IBSS (Ad-hoc) Devices connect directly without an access point. Useful for temporary file transfers. No central management; poor scalability. |
BSS (Infrastructure) One access point forms the cell. All clients communicate through the AP. Standard for home and business networks. |
ESS (Multi-AP) Multiple APs share the same SSID, connected via a wired backbone. Enables seamless roaming. Standard in enterprise, healthcare, education. |
Frequency Bands at a Glance
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2.4 GHz 2,400–2,497 MHz Standards: 802.11b/g/n/ax Range: up to ~70 m (indoors) Channels: 13 (EU), 3 non-overlapping Pro: Range, wall penetration Con: Crowded, many interference sources |
5 GHz 5,150–5,850 MHz Standards: 802.11a/n/ac/ax Range: up to ~35 m (indoors) Channels: up to 19 non-overlapping Pro: Less crowded, faster rates Con: Shorter range, weaker wall penetration |
6 GHz 5,925–7,125 MHz Standards: 802.11ax (Wi-Fi 6E), 802.11be Range: up to ~25 m (indoors) Channels: up to 24 x 80 MHz (EU) Pro: Barely used, maximum rates Con: Short range, new hardware required |
B2B Deployment Scenarios
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Office & Administration Laptops, smartphones, printers connected wirelessly. Typical: ESS with multiple APs, central management, 802.1X authentication against RADIUS. |
Production & Warehousing Barcode scanners, forklifts, AGVs via WLAN. Industrial WLAN: strict roaming requirements (<50 ms), high availability. IEEE 802.11r (Fast BSS Transition) essential. |
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Conference & Events High client density in small areas. 802.11ax (Wi-Fi 6) with OFDMA for efficient capacity distribution. Separate guest WLAN mandatory. |
Campus & Multi-Building Large-scale coverage with seamless roaming between buildings. WLAN controller or cloud management (Cisco Meraki, Aruba, Ubiquiti UniFi). |
Frequently Asked Questions
| What is the difference between WLAN and Wi-Fi? |
| WLAN is the technical term for a wireless local area network per IEEE 802.11. Wi-Fi is the certification mark of the Wi-Fi Alliance for interoperable devices. In everyday use, both terms are synonymous. |
| How far does a WLAN signal reach? |
| Outdoors: up to 100–150 m with standard APs. Indoors: 2.4 GHz typically 20–70 m, 5 GHz 15–35 m. Concrete and steel significantly reduce range. |
| What does SSID mean? |
| SSID stands for Service Set Identifier — the name of your WLAN that appears in network scans (e.g. "Company-WLAN"). Up to 32 characters long. An SSID can be broadcast on multiple APs simultaneously (ESS), so users always see the same network regardless of which AP they are connected to. |
| Is WLAN suitable for enterprise use? |
| Yes — with professional planning. Consumer routers are insufficient for 20+ concurrent users. Enterprise APs (Cisco, Aruba, Ubiquiti, Ruckus) offer multi-SSID, 802.1X, VLAN segmentation and central management. A site survey before installation is essential. |
| What is a WLAN controller? |
| A WLAN controller (WLC) is a central management instance for multiple access points, handling roaming, firmware updates, configuration and monitoring. Modern solutions are cloud-based (Cisco Meraki, Aruba Central, Ubiquiti UniFi Cloud). |
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Consulting & Supply Enterprise WLAN Hardware From access points to WLAN controllers and outdoor APs — our B2B sales team is happy to help with planning, procurement and technical questions. ► Phone: +49 (0)7666 / 88499-0 ► sales@industry-electronics.com |
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