![]() ![]() There is also a Low-power indoor (LPI) operation mode for use in indoor environments where access points are limited to a maximum EIRP of 30 dBm and a maximum power spectral density of 5 dBm/MHz. Regulations require standard mode power to be limited to 36 dBm and a maximum spectral density to 23 dBm/MHz. Standard operation mode is allowed for only U-NII 5 & 7 bands with automatic frequency coordination (AFC) which is a system that is aware of the location of the necessary services and will inform the access point (AP) of which parts of the spectrum it may operate, based on the AP’s location, antenna height, and transmit power. The Wi-Fi Alliance has introduced the term "Wi-Fi 6E" (802.11ax) to identify and certify Wi-Fi devices that support this band. U-NII 5 to 8 is an allocation of 1.2 GHz of unlicensed spectrum in the 6 GHz band (5.925–7.125 GHz) for Wi-Fi use. U-NII 4 (5.850–5.925 GHz) is presently only usable for Dedicated Short-Range Communications Service (DSRC)/ITS which is a one-way/two-way short to mid-range wireless communication designed for automotive applications and by licensed amateur radio operators. User-installable antennas are allowed in this band and power is limited to 1 W. U-NII 3 (5.725-5.850 GHz) is also called U-NII Upper or U-NII / ISM because it overlaps with the ISM band. The FCC added this spectrum to align the frequency bands used by U-NII devices in the US with bands in other parts of the world. It is subject to DFS and has its power limited to 250 mW. U-NII 2C (5.470–5.725 GHz) is also called U-NII Worldwide and is allocated for both outdoor and indoor use.U-NII 2B (5.350–5.470 GHz) currently has 120 MHz bandwidth of the spectrum unallocated by the FCC for unlicensed use.User-installable antennas are allowed for U-NII 2A and power is limited to 250 mW. According to regulations, it is subject to Dynamic Frequency Selection (DFS) or radar avoidance which is a mechanism to prevent electromagnetic interference with other usages of this frequency by technologies that predated WLAN such as military radar, satellite communications etc. U-NII 2A (5.250–5.350 GHz) is for both indoor and outdoor use.U-NII 2 (5.250-5.725 GHz) is divided into three subsections: Strict out-of-band emission rules for U-NII 1 limit its practical point-to-point power to lower levels. This was changed in 2014 to permit outdoor operation, increase maximum fixed power to 1 W, maximum fixed point-to-multipoint EIRP to 4 W (+36 dBm) and point-to-point EIRP of up to 200 watts (+53 dBm). Regulations require use of an integrated antenna for U-NII 1 with power limited to 50 mW. U-NII 1 (5.150–5.250 GHz) is also called U-NII Low and was limited to indoor use only. Licensed radio operators in the US are also authorized to utilize the 5.650–5.925 GHz U-NII frequency range by the FCC. Some wireless ISPs also use U-NII bands in the frequency 5.725–5.825 GHz. U-NII 1 to 4 are for 5 GHz WLAN (IEEE 802.11a and later) and U-NII 5 to 8 are for 6 GHz WLAN (802.11ax). ![]() U-NII consists of 8 ranges which are defined by the US FCC and named as U-NII 1 through 8. It is used by WLAN devices and some ISPs and radio operators. The Unlicensed National Information Infrastructure (U-NII) frequency bands are part of the radio frequency spectrum from 5.150-7.125 GHz defined by the US Federal Communications Commission (FCC). ![]()
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