The advantage of 5 GHz WiFi
2.4 GHz WiFi and 5 GHz WiFi in comparison
Advantages and disadvantages of 2.4 GHz WiFi
Fluctuating data rates or even connection failures of the WIFI network occur repeatedly in densely populated areas. The problem is caused by too much interference from other wireless networks that operate on the same frequency. In the 2.4 GHz range, 13 different channels are available, but only three of them are free of overlap and can therefore be used without any interference. The more traffic there is in the 2.4 GHz range, the more often there are collisions and the more the data rate and reliability decreases.
The advantage of 2.4 GHz networks is the (theoretically) higher range and compatibility with older end devices that do not support 5 GHz.
One difference between 2.4 and 5 GHz is the selection of available, overlap-free radio channels. The greatly increased use of wireless technology is leading to a considerable amount of individual radio networks in many areas. This means clearly noticeable interference, especially in data-intensive areas of application. Particularly in conurbations, there are insufficient spatial distances (approx. 30 – 40 m) between WIFI access points.
Overlap-free channels with 802.11b/g/n
- 20 MHz Channels: Channels 1, 6, 11 are overlap-free and can be operated without mutual interference.
- 40 MHz Channels: At 40 MHz channel bandwidth, channels 3+ and 11- are almost free of overlap and can be operated with little mutual interference.
- In mixed operation of 802.11b/g and 802.11n, it becomes clear that overlap-free use is hardly possible.
Advantages of 2.4 GHz WIFI
- Better penetration of walls compared to higher frequencies e.g. 5 GHz
- Compatibility with older and simpler devices
- Higher range with the same transmission power compared to 5 GHz WIFI
Disadvantages of 2.4 GHz WiFi
- Only three overlap-free channels
- Many other technologies also use 2.4 GHz (e.g. Bluetooth or Zigbee for home automation)
- Maximum 100 mW transmission power compared to 1000 mW with 5 GHz WiFi
Advantages and disadvantages of 5 GHz WiFi
With IEEE 802.11a/h (20 MHz bandwidth) a total of 19 non-overlapping channels are available in the 5 GHz spectrum. However, channels 120, 124 and 128 can only be used with severe limitations (weather radar channels).
So it is clear that a larger frequency band brings more space for parallel radio networks. In the 5 GHz range with 20 MHz channel width this means: 19 channels without overlap. Furthermore, many old WIFI devices are not designed for 5 GHz. This means that there are currently fewer subscribers in this range who must share the channels.
A prerequisite for using the upper channels at 5 GHz is the function of automatic frequency selection (DFS) and transmission power control (TPC) to bypass reserved frequencies and not to interfere with public devices (e.g. weather radar).
Additional improvement favoured by the 5 GHz range
With IEEE 802.11n (40 MHz bandwidth) a total of 9 non-overlapping channels are available. However, the channels 116+ and 124+ can only be used with severe limitations (weather radar channels).
To increase the data rate, it is possible to select larger channel widths, e.g. IEEE 802.11n offers a channel width of 20 MHz (transmission rate up to 288 Mbit/s), or 40 MHz (transmission rate up to 600 Mbit/s). The even more recent IEEE 802.11ac or the WiFi 6 standard can even bundle 80 and 160 MHz.
This means there is less space for channels in the frequency range, but a high data rate means that data packets are “processed” more quickly. The overall data exchange is thus shortened, and the router can handle more transmissions in the same time.
Wider road = less congestion during “rush hour”
Modern devices use MIMO (multiple input, multiple output) antenna technology. Which allows multiple connections simultaneously. Analogously described:
wider road (radio channel) and additional roads (antennas)
Overlap-free channels at 802.11a/h/n
In mixed operation of 802.11a/h and 802.11n networks, overlap-free use is possible even when weather radar channels are taken into account.
In addition, even with mixed operation of e.g. the standards IEEE 802.11a/h and IEEE 802.11n, largely overlap-free operation is possible. Modern routers can operate at 2.4 and 5 GHz. This means that a total of 527 MHz (minus reserved frequencies) is then available for distributing channels of different widths.
The comparatively short wavelengths and the associated short ranges are counteracted by the radio standards in the 5 GHz range with more transmission power. Hence the mandatory regulation (TPC).
Advantages of 5 GHz WiFi
- Up to 19 non-overlapping channels compared to 3 in the 2.4 GHz band
- Higher transmission power up to 1000 mW
- Fewer participants and other technologies in the 5 GHz band
Disadvantages of 5 GHz WiFi
- Not compatible with older access points
- Higher frequency thus lower penetration of walls