CompTIA A+ | Other Wireless Networks & Considerations

Bluetooth

Short-range wireless (about 10 meters) operating at 2.4 GHz. Creates a PAN (personal area network) for headsets, keyboards, mice, and speakers.

PAN (Personal Area Network)

A very small network around one person, usually created with Bluetooth.

Bluetooth frequency

2.4 GHz, which is why it can interfere with 2.4 GHz Wi-Fi.

NFC (Near Field Communication)

Extremely short range (about 4 cm or less). Used for tap-to-pay, badge access badges, toll passes, and pet microchips.

RFID (Radio-Frequency Identification)

Uses radio waves to read tags. Used for inventory tracking, access badges, toll passes, and pet microchips.

Passive RFID tag

Has no battery. It’s powered by the reader’s signal, so it only works at short range.

Active RFID tag

Has its own battery, so it can be read from much farther away.

NFC vs RFID

NFC is a type of RFID that works at very short range and allows two-way communication (like a phone paying at a terminal). RFID can work at longer range and is often one-way (reader reads a tag).

Bluetooth vs NFC range

Bluetooth reaches about 10 meters. NFC only works within a few centimeters.

A store wants to track inventory automatically as items move through the warehouse. What technology?

RFID

A user wants to pay by tapping their phone on a card reader. What technology?

NFC

A user wants to connect wireless earbuds to their phone. What technology?

Bluetooth

Employees tap their badge on a reader to unlock a door. What technology is likely used?

RFID or NFC

Wireless access point placement

Place if centrally and up high, away from thick walls, metal, and other sources of interference, for the best coverage.

What materials weaken Wi-Fi signals the most?

Concrete, brick, metal, and water (like aquariums). Glass and mirrors can also reflect signals.

Site survey

Walking through an area with a Wi-Fi analyzer to map signal strength, find dead zones, and plan where access points should go.

Dead zone

An area with little or no Wi-Fi signal.

A user has no Wi-Fi in the back bedroom of a large house. What are possible fixes?

Move the router to a more central spot, add an access point or mesh node, or connect to 2.4 GHz for better range.

Why should a router not be placed inside a cabinet or next to a microwave?

Enclosed spaces block the signal, and microwaves cause 2.4 GHz interference.

Which wireless technologies share the 2.4 GHz band and can interfere with each other?

Wi-Fi on 2.4 GHz and Bluetooth (plus microwaves and cordless phones).