Wi-Fi Terminologies & Important Notes

Wi-Fi 6e    * The 802.11ax Wi-Fi standard in 2021, but it is extended to the 6 GHz range for even more spectrum space. The 6 GHz expansion leads to even more stable connections and even less Wi-Fi interference.

802.11ax    * referred to as Wi-Fi 6 and the newest 2019 Wi-Fi standard.
   
OFDMA        * An updated version of OFDM. Orthogonal Frequency Division Multiple Access. Using multiple frequencies to carry data on multiple data streams to avoid inteference on a single stream.
Similar to CDMA (cellular division multiple access)

OFDM    * orthogonal frequency division multiplexing. It is a term used in legacy Wi-Fi networks preceding 802.11ac. Using multiple frequencies to carry data on multiple data streams to avoid inteference on a single stream.

BSS Color    * Basic Service Set color is a feature of Wi-Fi 6. It is used in SSIDs to solve high density. an AP + 1 user = a BSS. identifying each individual BSS, helps in re-using spatial streams within a channel.

TWT    * a feature of Wi-Fi 6, Target Wake Time is used to increase the efficiency of battery life in Wi-Fi 6 devices only. Wi-Fi 6 enabled devices, can sleep their Wi-Fi connection and resume as soon as data as transmitted, rather than always being on.

PHY     * predicitive physical data rate within 150m
    * data rates are measured by Megabytes per second or Mbps

dBm     * decibel milliwatts measures signal strength range
        -70 dBm (minus 70) is the minimum but poor signal
        -67 dBm is nearly double the data rate and is optimal (-3 difference is double)
        -30 dBm is at the maximum end and is usually only 5ft or less away from AP
 

Acceptable Signal Strengths

RSSI	Rating	Requirement for
-30 dBm	Amazing	Max achievable signal strength.         The client can only be a few feet from the AP to achieve this. Not typical or desirable in the real world.     N/A
-67 dBm	Very Good	Minimum signal strength for applications that require very reliable, timely delivery of data packets.    VoIP/VoWiFi, streaming video
-70 dBm	Okay	Minimum signal strength for reliable packet delivery.            Email, web
-80 dBm	Not Good	Minimum signal strength for basic connectivity.         Packet delivery may be unreliable.    N/A
-90 dBm	Unusable	Approaching or drowning in the noise floor.         Any functionality is highly unlikely.    N/A
(source =  http://www.metageek.com/training/resources/understanding-rssi.html )

MIMO    multiple-input and multiple-output. Similar to OFDM in concept. Specifically refers to a practical technique for sending and receiving more than one data signal simultaneously over the same radio channel by exploiting multipath propagation.

RSSI    * received signal strength indication
    * Cisco RSSI is usually measured from 1 to 100 and is similar to dBm
    * the higher the number, the more powerful the connection and signal

There is sometimes confusion with SNR vs RSSI (Received Signal Strength Indicator) vs Signal Strength. Cisco RSSI is always measured in positive values ranging from 0 to 100 in order to simplify the relative measurement. The true value of RSSI is difficult to interpret as different manufacturer brands use different scales. Atheros uses a scale from 0 to 60. Cisco uses 0 to 100. Other manufacturers may use anything between 0 and 255.

RTLS    * Real-time locating system.
    * used to automatically identify and track the location of objects or people (RFIDs) in real time, usually within a building or other contained area.

RFID    * Radio-Frequency Identification.
    * a small device used in RTLS systems as tracked units. Also referred to as Smart Labels. Can be attached to inventory as tags. Can also be used as wrist-bands on individuals.

WIDS/WIPS    * Wireless Intrusion Detection Software, and Wireless Intrusion Prevention Software

802.11ac Backwards Compatibility:
The AC standard is backwards compatible with 802.11n. All connected clients do not revert downward to 802.11n and AC will support both clients simultaneously. This is a feature of the new Wi-Fi 80211ac 5 GHz band.

On the 2.4Ghz band the same is not true. It is opposite. For example ‘N’ standard down to ‘G’ or from ‘G’ standard down 802.11b standard, the lowest common denominator will revert the whole section of LAN subnetwork to the speed of the slowest client connected.

Bluetooth operates on the 2.4 Ghz frequency. Similar to 802.11g/n. Used in short range wireless electronic accessories.

Cellular mobile phones operate on the 800Mhz and 1900Mhz frequencies typically.

DECT (6.0)    * wireless phone standard designed to minimize interference with Wi-Fi
        * Digital Enhanced Cordless Telecommunications
        * operates on 1920 MHz–1930 MHz, or 1.9 GHz
        * older generation cordless phones without DECT usually used 2.4 GHz which interferes with Wi-Fi.

Typical Wi-Fi Range    * 802.11b/g (2.4Ghz) WAPs and routers support a range of up to 150 feet (46 m) indoors and 300 feet (92 m) outdoors. (75 ft radius from center)
        * 802.11a (5.0Ghz) is approximately one-third or 50 feet propogation. (25 ft radius from center)

QAM    * Quadrature amplitude modulation
Quadrature amplitude modulation (QAM) uses both the phase and amplitude of a radio frequency signal to represent data bits. WiFi 6 will support 1024-QAM and new modulation and coding schemes that define higher data rates.