Читать книгу High-Density and De-Densified Smart Campus Communications - Daniel Minoli - Страница 41

The 802.11ac system throughput is at, or greater than 1 Gbps and single‐link throughput of at least 0.5 Gbps; 800 ns guard intervals are supported. Figure 2.9 depicts available frequencies for the 802.11ac LAN environment. Dynamic Frequency Selection (DFS) is a Wi‐Fi function that enables WLANs to use 5 GHz frequencies that are generally reserved for radars; these are less‐crowded Wi‐Fi bands and can be utilized to increase the number of available Wi‐Fi channels, especially in (residential) multi‐dwelling units. When support for DFS is enabled, it will be necessary for the AP to verify that any radar in proximity is not using DFS frequencies; this is done by a process called Channel Availability Check, which is executed during the boot process of the AP and also as during its normal operations. See Table 2.5 [22].

FIGURE 2.9 5GHz spectrum usability for IEEE 802.11ac LANs.

TABLE 2.5 5 GHz Wi‐Fi Frequencies

Band	Channel	Frequency (MHz)
U‐NII‐1	36–48	5170–5250
U‐NII‐2A/DFS	52–64	5250–5330
U‐NII‐2C/DFS	100–140	5490–5710
U‐NII‐3	149–165	5735–5835