WiFi abbreviations

Abbreviations

WiFi or 802.11 abbreviations

Abb.	meaning	Notes
ASK	Amplitude Shift Keying	Keying 0's and 1's by altering the radio carriers amplitude
FSK	Frequency Shift Keying	Keying 0's and 1's by altering the radio carriers frequency
PSK	Phase Shift Keying	Keying 0's and 1's by altering the radio carriers phase
MPSK	Multiple Phase Shift Keying	Keying more than one bit at a time by using four or more phases
IR	Intended Radiator	The active RF transmitter
RF	Radio Frequency	Rate of oscillation in the range of around 3 kHz to 300 GHz corresponding to radio waves
FSPL	Free Space Path Loss	Loss of amplitude of the signal in free space over distance
ISI	Intersymbol Interference	Signal misinterpreted by receiver due to multipath signals out of phase
EIRP	Equivalent isotropically radiated power	The highest RF signal strength transmitted from a particular antenna. Often expressed in dBm
RSSI	Received Signal Strength Indicator	power level received by the receiver radio in dbm
mW	Milli Watt	0,001 Watt
dB	Decibel	Logarithmic unit used to express the ratio between two values. dB = 10 x log10 Ratio1 / Ratio2
dBm	Decibel milliwatt	Decibel relative to 1 mW of power.
dBi	Decibel isotropic	Antenna gain compared to a theoretical isotropic antenna
dBd	Decibel dipole	Antenna gain compared to a theoretical isotropic antenna. Add 2,14 dB to get dBi
SNR	Signal to Noise Ratio	Distance between received signal and noise floor. Expressed in dB
DRS	Dynamic Rate Switching	Switching to a higher/lower data rate as the received signal increases/decreases
ISM	Industrial Scientific and Medical	902 - 928 MHz, 2,4 - 2,5 GHz and 5,725 - 5,875 GHz bands
UNII	Unlicensed National Information Infrastructure	Three 5 Ghz bands each with 100 MHz bandwidth
UNII-1	UNII-1 (lower band)	5,150 - 5,250 GHz band ( 4 channels )
UNII-2	UNII-2 (Middle band)	5,250 - 5,350 GHz band ( 4 channels )
UNII-2E	UNII-2 Extended	5,470 - 5,725 GHz band 255 MHz bandwidth ( 11 channels )
UNII-3	UNII-3 (Upper band)	5,725 - 5,825 GHz band ( 4 channels )
FHSS	Frequency Hopping Spread Spectrum	Transmitting data in small chunks hopping from frequency to frequency
DSSS	Direct Sequence Spread Spectrum	Transmitting data is spread across the range of frequencies of the channel. 11 bit PN
GFSK	Gaussian Frequency Shift Keying	FSK modulator using a Gaussian filter to reduce spectral width.
PN	Pseudorandom number	Used with DSSS to encode 1 bit to 11 bits to reduce transmission errors.
CCK	Complementary Code Keying	Used with HR-DSSS to encode 4 bits data to 8 bits using a 8 bit PN
HR-DSSS	High Rate DSSS	Uses CCK encoding to get higher data rate than DSSS
DQPSK	Differential Quadrature Phase Shift Keying	Modulation using four phase shifts each representing two bits
OFDM	Orthogonal Frequency Division Multiplexing	Popular Spread Spectrum technology transmitting between 52 subcarriers
FEC	Forward Error Correction	Allows the receiving system to detect and correct bit errors.
WWAN	Wireless Wide Area Network	Wireless Network spanning wide areas for example GSM or LTE
WMAN	Wireless Metropolitan Area Network	Wireless Network spanning cities for example WiMax
WPAN	Wireless Personal Area Network	Wireless Network spanning small personal areas for example Bluetooth or infrared
WLAN	Wireless Local Area Network	Wireless Network spanning buildings/campusses for example WiFi/802.11
IS	Integration Service	The process of transforming the MSDU (802.11) frame to other frame standards. Normally ethernet
DS	Distribution System
CAM	Content Addressable Memory	MAC address table in a switch used to process packets based on destination MAC address
DSS	Distributed System Services
MSDU	MAC Service Data Unit	Upper layer information in data unit in the body of a 802.11 data frame
WDS	Wireless Distribution System
SSID	Service Set Identifier
BSS	Basic Service Set
BSSID	Basic Service Set Identifier
BSA	Basic Service Area
ESS	Extended Service Set
IBSS	Independent Basic Service Set
MBSS	Mesh Basic Service Set
AP	Access point	Gives wireless clients access to the network services.
DCF	Distributed Coordination Function	The 802.11 fundamental media access method.
PCF	Point Coordination Function	Access Point coordinated media access.
HCF	Hybrid Coordination Function
CSMA/CA	Carrier Sense Multiple Access with Collision Avoidance	Wireless media access method principle.
IFS	Interframe Space	period of time that exists between transmissions of wireless frames.
RIFS	Reduced Interframe Space	Highest priority IFS
SIFS	Short Interframe Space	Second highest priority IFS
PIFS	PCF Interframe Space	Middle priority IFS
DIFS	DCF Interframe Space	Lowest priority IFS
AIFS	Arbitration Interframe Space	IFS used by QoS stations
EIFS	Extended Interframe Space	IFS used with retransmissions.
ACK frame	Acknowledge Frame	Acknowledge the reception of a frame by transmitting an acknowledge frame.
RTS	Request To Send	A signal requesting the wireless media.
CTS	Clear To Send	A signal after RTS acknowledging permission to transmit.	-	NAV	Network Allocation Vector	A timer initiated by the Duration field in 802.11 frames by stations. It is illegal to transmit in this period. Also known as Virtual Carrier sense. Operates on OSI layer 2.
CCA	Clear Channel Assesment	Listening to physical medium if a transmission is in progress. Also known as Physical Carrier Sense. Operates on OSI layer 1.