IEEE802.11b/IEEE802.11g channels

IEEE802.11b/IEEE802.11g channels

 The IEEE802.11b standard is compatible with the existing IEEE802.11 standard. The wireless frequency uses the 2.4 GHz band, and the transmission speed can be increased from 2 Mbps to a theoretical maximum of 11 Mbps. Data communication is possible in a wide range even in the house, and it can be used stably because there is little interference with other devices that use radio waves.

 Like IEEE802.11g, it can be used in public spaces (stations, public institutions, lodging facilities, cafes, etc.) with wireless LAN access points called free spots.

*The maximum transfer speed is a theoretical speed. Effective speed may be slower due to communication procedures, etc.

 IEEE802.11b can use 14 channels from 1ch to 14ch. Note that IEEE802.11g, which is backward compatible, has 13 channels from 1ch to 13ch.

 As shown in the figure below, the number of channels that can be used simultaneously is four. In order not to cause radio wave interference, it is necessary to leave a space of 5 channels or more.

That's because the channel spacing is 5MHz and the width of one channel is 22MHz.

Since 14ch is a channel that exists only in Japan, the number of channels that can be used simultaneously is 3 overseas.

 The combinations of channels that can use 4 channels at the same time are 1ch/6ch/11ch/14ch. If you do not use 4 channels at the same time, combinations of 3ch/8ch/13ch, etc. are possible.

IEEE802.11g channel

 IEEE802.11g is an upward compatible method of IEEE802.11.b and can also support the IEEE802.11.b method. Therefore, if IEEE802.11.b is used to build a wireless LAN, IEEE802.11g can be used for smooth migration.

The radio frequency uses the same 2.4GHz band as IEEE802.11.b, and the theoretical maximum transmission speed is 54Mbps.

*The maximum transfer speed is a theoretical speed. Depending on the communication procedure, etc., the effective speed will be slower.

 In IEEE802.11b, 14 channels from 1ch to 14ch can be used, but in IEEE802.11g, 13 channels from 1ch to 13ch can be used. Note that the number of channels that can be used is different.

 IEEE802.11g cannot use 14ch, so the number of channels that can be used simultaneously is 3 as shown in the figure below. In order to prevent radio wave interference, it is necessary to leave a space of 5 channels or more, as with IEEE802.11b.

That's because the channel spacing is 5MHz and the width of one channel is 22MHz.

 Combinations of 1ch/6ch/11ch, 2ch/7ch/12ch, 3ch/8ch/13ch, etc. can be used for channels that can be used simultaneously. You can use 1ch/7ch/13ch with enough space.

When IEEE802.11b and IEEE802.11g are mixed

 IEEE802.11g is backward compatible with IEEE802.11b, allowing communication between the two standards. If you look at the channel layout diagram below, you can see that the same frequency band is used.

 However, if the same channel is used in a mixed environment with IEEE802.11b, it will be adjusted to the IEEE802.11b side. As a result, the communication speed of IEEE802.11g terminals decreases.

 IEEE802.11g is a system that is upwardly compatible with IEEE802.11.b and is compatible with the IEEE802.11.b system. , can be migrated.

 In an environment where IEEE802.11b and IEEE802.11g coexist, it will be matched to the IEEE802.11b side, so it is desirable to unify with IEEE802.11g equipment at an early stage.