Computer Networking Basics
Which correctly describes a general difference between the 2.4 GHz and 5 GHz bands of wireless LAN?
- AThe 2.4 GHz band reaches farther even with obstacles, but it is shared with microwave ovens, Bluetooth and others, so it gets congested easily and has few non-overlapping channels
- BThe 5 GHz band passes through walls and other obstacles more easily than the 2.4 GHz band and reaches farther
- CThe 2.4 GHz band is allocated exclusively to wireless LAN, so it suffers no interference from other devices
Show answer and explanation
Answer: A. The 2.4 GHz band reaches farther even with obstacles, but it is shared with microwave ovens, Bluetooth and others, so it gets congested easily and has few non-overlapping channels
In general, the higher the frequency, the more easily radio waves are weakened by walls and other obstacles and the shorter their range. The 2.4 GHz band reaches well, but as a licence-free ISM band it is used by many devices such as microwave ovens and Bluetooth, so it suffers interference, and only about three or four 20 MHz channels do not overlap one another. The 5 GHz band has more channels and makes it easy to bond them into wider channels for higher speed, but it is weaker against obstacles, and some channels require the DFS procedure to avoid interfering with weather radar and the like. In the 2020s, Wi-Fi 6E and Wi-Fi 7 also opened up the 6 GHz band (the usable range differs by country and region).
- A. Correct. It has both better reach and more congestion.
- B. The higher-frequency 5 GHz band is generally weakened more by obstacles and has a shorter range.
- C. The 2.4 GHz band is an ISM band shared with microwave ovens, Bluetooth and others.