---
title: "Short note: Wireless LAN (WLAN)"
subject: "Wireless Communication"
chapter: 8
key: "semester_7/wireless_communication:wlan-short-note"
source: https://www.bctengineer.com/q/semester_7/wireless_communication/wlan-short-note
site: BCT Engineering
---

# Short note: Wireless LAN (WLAN)

Wireless Communication · Chapter 8: Wireless Systems and Standards

- Asked in: 2075 Bhadra, 3 marks
- Video: [Wireless Networking Explained | Cisco CCNA 200-301](https://www.youtube.com/watch?v=Uz-RTurph3c) — CertBros
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/wireless_communication/wlan-short-note
- Whole chapter: https://www.bctengineer.com/md/semester_7/wireless_communication/chapter-8

## Question

Write a short note on Wireless Local Area Network (WLAN).

## Short answer

A WLAN connects devices over short range using radio, mostly IEEE 802.11 in 2.4/5 GHz. It has stations and access points, with infrastructure or ad hoc modes. MAC uses CSMA/CA with ACKs and optional RTS/CTS; rates range from 11 Mbps to several Gbps with WPA2/WPA3 security.

## Answer

A **Wireless Local Area Network (WLAN)** links devices within a limited area (home, office, campus) using radio waves instead of cables. Most WLANs follow **IEEE 802.11 (Wi-Fi)** and operate in the unlicensed 2.4 GHz and 5 GHz bands.

- **Components**: stations (STA) and access points (AP); an AP connects wireless users to the wired LAN.
- **Modes**: infrastructure (via AP, BSS/ESS) and ad hoc (IBSS, device to device).
- **MAC**: CSMA/CA with ACKs and optional RTS/CTS.
- **PHY**: DSSS (802.11b), OFDM (802.11a/g), OFDM + MIMO (802.11n/ac), OFDMA (802.11ax); rates from 11 Mbps to several Gbps.
- **Security**: WPA2/WPA3 with AES encryption.

```text
 [Laptop]~~\
 [Phone]~~~[AP]---LAN/Internet
```

Advantages: mobility, easy installation, low cost. Drawbacks: limited range (~100 m), interference and shared bandwidth.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. A WLAN links devices in a limited area using:
   A. Optical fibre only
   B. Licensed cellular spectrum only
   C. Power lines
   D. Radio waves, mostly IEEE 802.11 in unlicensed bands
   Answer: D. WLANs mostly follow 802.11 in 2.4/5 GHz unlicensed bands. (Key point: Definition)

2. What does an access point do?
   A. Allocates GSM time slots
   B. Encrypts speech with A5
   C. Connects wireless stations to the wired LAN
   D. Replaces the stations' antennas
   Answer: C. The AP bridges wireless users to the wired network in infrastructure mode. (Key point: AP role)

3. What is ad hoc (IBSS) mode?
   A. All traffic goes via the AP
   B. Mode used only in 802.11b
   C. Mode where APs form ESS
   D. Devices communicate directly without an AP
   Answer: D. Infrastructure uses an AP; ad hoc is device-to-device. (Key point: Modes)

## Related in Wireless Communication

- [Numerical: 32-cell system area and channels](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Acellular-32-cells-capacity) — Wireless Communication, chapter 2
- [Numerical: cluster size and users in service area](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Acluster-size-users-service-area) — Wireless Communication, chapter 2

## Related in other subjects

- [Short note: Network topologies and IBM Ring LAN](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Ashort-note-topologies-ibm-ring) — Telecommunications, chapter 8
- [Network planning for remote area telephony](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Anetwork-planning-remote-area) — Telecommunications, chapter 1
- [Design network for two buildings with fiber](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Anetwork-design-guidelines-two-buildings) — Internet and Intranet, chapter 5
- [Redundant hierarchical network design for bank](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aredundant-network-bank-four-departments) — Internet and Intranet, chapter 5