Every term this site assumes you already know
96 terms across frames, addressing, connection state, security, RF, airtime and spectrum regulation. Defined plainly first, with the clause noted where the standard defines it. If a term stops you on another page, look it up here.
Terms that do not belong to IEEE 802.11 carry a label saying whose they are. DFS and TPC are 802.11 mechanisms that regulators oblige you to use; AFC is an FCC construct; WMM, WPA2 and WPA3 are Wi-Fi Alliance certifications; RX-SOP is a vendor feature with no standard behind it. Conflating these is the most common error in Wi-Fi writing.
— Shankar K. · Clause references verified August 2026 against IEEE 802.11-2024 ·
the IEEE family of standards for wireless LANs. 'Wi-Fi' is the Wi-Fi Alliance's certification brand for products built on it.
the medium access control layer: who may transmit and how frames are addressed.
one labeled package of bits sent over the air. The unit of 802.11 communication.
eight bits; one byte.
the first two bytes of every frame; says what the frame is (Clause 9.2.4.1).
Frame Check Sequence: a 4-byte checksum that detects corruption (Clause 9.2.4.9).
frame and fragment numbers, for ordering and de-duplication (Clause 9.2.4.4).
a tag-length-value unit inside a frame body: Element ID, Length, then that many bytes (Clause 9.4.2.1).
a capture-time header (signal strength, channel, rate) added by the radio; not part of 802.11.
the network's paperwork: beacons, probes, authentication, association.
frames that end a connection; a burst can signal an attack.
Receiver Address / Transmitter Address: who a frame is for, and who sent it.
two Frame Control bits that decide what Address 1-4 mean (Clause 9.2.4.3).
the value a station keeps for every peer it talks to directly, tracking whether that peer is authenticated and associated (Clause 11.3.1). It has five values.
authenticated by PASN, unassociated. A side branch: association is not possible from here without a non-PASN authentication first.
associated, with the RSNA still pending. The 802.1X controlled port is blocked.
associated, with the RSNA established or not required. The port is open and data flows.
the grouping that decides which frames a station may send in which state (Clause 11.3.3). There are four: Class 1, Class 1a, Class 2, Class 3.
Class 1 is always allowed; Class 2 needs authentication; Class 3 needs association. Class 1a is the PASN branch.
Pre-Association Security Negotiation (Clause 12.13): protected management exchanges, such as secure ranging, without ever associating.
Robust Security Network Association: an association secured by the RSN machinery. An association that is not an RSNA (an open network) goes from State 2 straight to State 4.
the gate that holds real data back until the RSNA completes. Separate from frame-class filtering; a Class 3 frame can be permitted while the port is shut.
says why a connection was torn down; rides in Deauthentication and Disassociation (Clause 9.4.1.7, Table 9-79).
says whether a request succeeded; rides in Association and Authentication responses (Clause 9.4.1.9, Table 9-80). Status 0 is success.
Pairwise Master Key: the shared secret both sides already hold before the handshake starts. It is never transmitted.
Pairwise Transient Key: the per-session key derived from the PMK plus both nonces and both MAC addresses. It partitions into four parts (Clause 12.7.1.3).
Key Confirmation Key: provides data origin authenticity for the handshake messages. This is what computes the MIC.
Key Encryption Key: provides confidentiality for those messages, and wraps the GTK inside M3.
Key Derivation Key: the fourth part, derived only when WUR frame protection is negotiated or secure HE-LTF applies. Usually absent.
the random values contributed by the Authenticator and the Supplicant. Mixed into the PTK so every session key is fresh. The ANonce is identical in M1 and M3.
the message format all four handshake messages use. They are told apart by flags, not by shape (Clause 12.7.6.8).
Message Integrity Code: proves a handshake message was not altered and that the sender holds the right key. With an AEAD cipher there is no MIC field at all; integrity comes from the AEAD decryption instead.
Group Temporal Key: protects group-addressed (broadcast and multicast) traffic. The AP delivers it wrapped inside M3.
Integrity Group Temporal Key: protects group-addressed management frames when PMF is negotiated. Also delivered in M3.
Robust Security Network Element: the element advertising the ciphers and AKM a station supports. The handshake binds it to detect downgrade attempts.
the client side and the AP side of the handshake, in IEEE 802.1X terms.
Authentication and Key Management suite: how the two sides authenticate and derive keys (PSK, SAE, 802.1X, FT, and so on).
Received Signal Strength Indicator: a summary of received power, reported by the radio. Vendor-scaled and not comparable across chipsets. In a capture it is what the sniffer heard, not what the AP or the client heard.
Signal-to-Noise Ratio: signal power above the noise floor. A better predictor of achievable rate than RSSI, because a strong signal in a noisy room still decodes badly.
three ways to state radiated power. EIRP is power in the direction of maximum antenna gain, referenced to an isotropic radiator, and is what most regulatory limits are written in. ERP is EIRP minus 2.15 dB, referenced to a dipole. TRP is total power radiated in all directions.
Orthogonal Frequency Division Multiplexing: the modulation used from 802.11a onward. Data rides many narrow subcarriers in parallel rather than one wide one.
Modulation and Coding Scheme: an index naming a modulation order and coding rate. With bandwidth, spatial streams and guard interval it determines the PHY rate. A low MCS at good RSSI usually means interference or multipath, not distance.
one independently modulated data stream in a MIMO transmission. More streams need a channel rich enough to keep them separable, which dense environments erode.
Multiple-Input Multiple-Output: multiple antennas carrying multiple spatial streams. MU-MIMO serves several stations at once on different streams.
the gap between OFDM symbols that absorbs multipath delay spread. Shorter is faster and less tolerant.
transmitting on a wide channel with some subchannels disabled, so a 160 MHz operation survives one busy 20 MHz segment instead of falling back wholesale.
a six-bit identifier in the HE and EHT PHY header letting a receiver decide early whether a frame is intra-BSS or inter-BSS, which is what enables spatial reuse. Two nearby APs sharing a colour cause a collision and lose the benefit.
Multi-Link Operation: a Wi-Fi 7 capability where one logical device holds links on several bands at once.
Multi-Link Device: the logical entity above the per-link stations in MLO. Higher layers see the MLD MAC address, which is why one identity can legitimately appear on several BSSIDs at the same time. Any tool reasoning about duplicate addresses has to know this.
the contention model: listen before transmitting, and back off a random interval to reduce the chance that two stations start together.
Clear Channel Assessment: the physical check that the medium is busy. Two forms, carrier sense (a decodable 802.11 preamble) and energy detect (raw RF above a threshold).
Enhanced Distributed Channel Access: QoS channel access with four access categories, each with its own contention parameters, so voice contends harder than background.
the four EDCA classes: voice, video, best effort, background. Mapped from the user priority in the QoS Control field.
interframe spaces. SIFS is the short gap before an immediate response such as an ACK. DIFS is the longer gap before contending. AIFS is the EDCA per-category version of DIFS.
the range a station draws its random backoff from. It doubles on each failure, which is why a congested cell degrades faster than linearly.
Transmit Opportunity: a bounded window won by contention, during which a station may send more than one frame.
two ways to aggregate. A-MSDU packs several payloads under one MAC header. A-MPDU concatenates whole frames, each keeping its own header and FCS, so one bad subframe does not cost the rest.
Target Wake Time: a negotiated schedule letting a station sleep outside agreed service periods. Individual and broadcast variants exist.
a bit in Frame Control saying this frame has been sent before. A high retry rate with good RSSI points at contention or interference rather than range.
co-channel interference is energy you cannot decode, which costs SNR. Co-channel contention is a signal you can decode and therefore defer to, which costs airtime. They are different problems with different fixes.
Receiver Start of Packet: a vendor threshold below which the radio ignores a preamble outright. Not an IEEE mechanism. Raising it makes an AP deliberately deafer, which changes what appears in a capture taken near it.
the 2.4 GHz range shared with microwave ovens, Bluetooth and much else. Globally available and correspondingly crowded.
the subdivisions of 5 GHz and 6 GHz spectrum, each with its own rules on power, indoor use and radar avoidance. The band a channel sits in decides what is permitted, not the channel number.
Dynamic Frequency Selection: vacating a channel when radar is detected. 802.11 defines the mechanism; the obligation to implement it, and the detection thresholds and timers, come from regulators such as the FCC and from ETSI EN 301 893 in Europe.
Channel Availability Check: the listening period before first use of a DFS channel. A DFS channel is not usable the instant it is selected, which is why a DFS-triggered move looks like an outage rather than a handover.
Non-Occupancy Period: the interval a channel must stay unused after radar was detected on it.
Transmit Power Control: reducing power when full power is not needed. Required alongside DFS in the EU under ETSI EN 301 893; without it the permitted EIRP is lower.
Automated Frequency Coordination: a database that grants channels and power to standard-power 6 GHz devices by geolocation, protecting incumbent fixed links. An FCC and ISED construct, not an IEEE one, and not implemented in every region.
the three 6 GHz power classes. Low Power Indoor is indoor-only without coordination, Very Low Power is lower still and mobile, Standard Power is higher and requires AFC.
the country rules a device enforces, advertised in the Country element. A client that trusts a beacon's country code will follow it, which is why a wrong country code is a compliance problem and not a cosmetic one.
Wi-Fi Alliance generation names, not IEEE names. They map to 802.11n, ac, ax, ax on 6 GHz, and be. The Alliance certifies interoperability; IEEE publishes the standard. Wi-Fi 1, 2 and 3 are informal and were never used by the Alliance.
Wi-Fi Multimedia: the Wi-Fi Alliance certification name for EDCA. Seeing WMM in a product sheet means EDCA in the standard.
Wi-Fi Alliance certification programmes, not IEEE standards. They select and mandate subsets of what 802.11 permits, which is why a WPA3 requirement and an 802.11 requirement are not the same claim.
a packet-capture file; the recorded frames a forensic tool reads.
a NIC mode that captures all frames in the air, not just those addressed to it.
reading captured frames to explain what happened and why.