| AID | Association ID | 1-2007 identifier AP assigns at association; indexes the TIM bitmap. |
| AKM | Authentication & Key Management | RSN suite selecting auth method + key hierarchy (PSK, 802.1X, SAE, FT variants…). |
| A-MPDU / A-MSDU | Aggregated MPDU / MSDU | Frame aggregation - see Aggregation & Block Ack sheet. |
| ANQP | Access Network Query Protocol | Pre-association network info queries (Passpoint). |
| BA / BAR | Block Ack / BA Request | Selective acknowledgment of aggregated frames. |
| BSS / ESS / IBSS | Basic/Extended/Independent Service Set | One AP+clients / multiple APs same SSID+DS / ad-hoc. |
| BSSID | BSS Identifier | MAC address of the BSS (per-radio, per-SSID). |
| BSR / BSRP | Buffer Status Report (Poll) | UL queue-depth feedback feeding OFDMA scheduler. |
| BTM | BSS Transition Management | 802.11v steering request/response. |
| CCA | Clear Channel Assessment | PHY busy/idle decision (preamble -82 / energy -62 dBm @20 MHz). |
| CCMP / GCMP | Counter-mode CBC-MAC / Galois-Counter Protocol | AES encryption protocols; GCMP-256 in WPA3-192. |
| CSA / eCSA | (Extended) Channel Switch Announcement | Beacon countdown to a channel move (DFS). |
| CSI | Channel State Information | Per-subcarrier channel estimate; basis of beamforming & sensing. |
| CW | Contention Window | Backoff range; doubles on retry. |
| DCF / EDCA / HCF | Distributed/Enhanced Coordination Function | Base CSMA/CA; QoS 4-queue version; hybrid umbrella. |
| DFS | Dynamic Frequency Selection | Radar detect/avoid in 5 GHz UNII-2. |
| DPP | Device Provisioning Protocol | Wi-Fi Easy Connect (QR-code onboarding). |
| DS / DSCP | Distribution System / Diff-Serv Code Point | Wired backbone; L3 QoS marking. |
| DTIM | Delivery Traffic Indication Map | Beacon multiple after which broadcast/multicast is delivered. |
| EAP(OL) | Extensible Auth Protocol (over LAN) | 802.1X framing; EAPOL-Key = 4-way handshake frames. |
| EHT / HE / VHT / HT | Extremely High / High Efficiency / Very High / High Throughput | PHY names: 11be / 11ax / 11ac / 11n. |
| EIRP | Effective Isotropic Radiated Power | Conducted power + antenna gain - losses. |
| EMLSR / EMLMR | Enhanced Multi-Link Single/Multi Radio | MLO modes - see MLO sheet. |
| ERP | Extended Rate PHY | 802.11g OFDM in 2.4 GHz. |
| EVM | Error Vector Magnitude | TX constellation quality (dB); gates high QAM. |
| FILS | Fast Initial Link Setup | 802.11ai fast connect; also 6 GHz Discovery frames. |
| FT / FTE / MDE | Fast Transition (Element) / Mobility Domain Element | 802.11r roaming machinery. |
| GAS | Generic Advertisement Service | Transport for ANQP pre-association. |
| GI | Guard Interval | Symbol gap absorbing delay spread (0.4-3.2 µs). |
| GTK / IGTK / PTK / PMK | Group/Integrity-Group/Pairwise-Transient/Pairwise-Master Key | Key hierarchy - see 4-Way sheet. |
| H2E | Hash-to-Element | SAE PWE derivation; mandatory on 6 GHz (RSNXE bit 4). |
| HESSID | Homogeneous ESS ID | Passpoint operator network identifier. |
| KDE | Key Data Encapsulation | TLVs inside EAPOL-Key (GTK, IGTK, MLO links…). |
| LDPC / BCC | Low-Density Parity Check / Binary Convolutional Coding | FEC codes; LDPC ≈ 1.5-3 dB better. |
| MBSSID | Multiple BSSID | Many SSIDs in one beacon (6 GHz mandatory concept). |
| MCS | Modulation & Coding Scheme | Index selecting modulation+coding (+NSS in 11n). |
| MFP / PMF | Management Frame Protection | 802.11w; MFPC/MFPR bits in RSN caps. |
| MIMO / MU-MIMO / SU | (Multi-User) Multiple-In Multiple-Out | Spatial multiplexing to one/many receivers. |
| MLD / MLO | Multi-Link Device / Operation | Wi-Fi 7 multi-band association - see MLO sheet. |
| MPDU / MSDU / PPDU / PSDU | MAC Protocol/Service Data Unit; PHY Protocol/Service DU | MSDU=payload in; MPDU=framed; PSDU=bits to PHY; PPDU=on-air w/ preamble. |
| MRU | Multi-RU | Multiple RUs to one STA (11be). |
| NAV | Network Allocation Vector | Virtual carrier-sense countdown from Duration field. |
| NDP / NDPA | Null Data Packet (Announcement) | Sounding frames for beamforming. |
| NSS | Number of Spatial Streams | Parallel MIMO streams. |
| OBSS / OBSS-PD | Overlapping BSS (Preamble Detect) | Neighbor cell; 11ax spatial-reuse threshold. |
| OFDM(A) | Orthogonal Frequency Division Multiplexing (Access) | Multicarrier PHY; OFDMA = subcarriers shared among users. |
| OKC | Opportunistic Key Caching | Pre-11r PMK sharing across APs (vendor). |
| OWE | Opportunistic Wireless Encryption | Enhanced Open - encryption without password. |
| PER | Packet Error Rate | Target ≤10% at sensitivity spec. |
| PHY | Physical Layer | - |
| PMKID | PMK Identifier | Cache handle: HMAC(PMK, "PMK Name"|AA|SPA). |
| PPE | PPDU Packet Extension | Trailing µs giving receivers decode time (HE). |
| PSC | Preferred Scanning Channel | 6 GHz every-4th-channel scan set. |
| QAM | Quadrature Amplitude Modulation | Amplitude+phase constellations (16→4096). |
| RA / TA / DA / SA | Receiver/Transmitter/Destination/Source Address | See MAC Header Anatomy. |
| RCPI / RSNI | Received Channel Power / SNR Indicator | 802.11k measurement units. |
| RNR | Reduced Neighbor Report | Out-of-band discovery IE 201. |
| RSSI | Received Signal Strength Indicator | Vendor-scaled RX power (dBm-ish). |
| RSN(E) / RSNXE | Robust Security Network (Extension) Element | IE 48 / IE 244 - see security sheets. |
| R-TWT | Restricted Target Wake Time | Protected latency service periods (11be). |
| RU | Resource Unit | OFDMA tone block (26-996×4). |
| SAE | Simultaneous Authentication of Equals | WPA3-Personal Dragonfly PAKE. |
| SCS | Stream Classification Service | Flow-QoS signaling (11aa/11be). |
| SIFS / DIFS / AIFS / EIFS | Inter-Frame Spaces | 16 µs / 34 µs / per-AC / error-recovery gap. |
| SNR / SINR | Signal-to-(Interference-and-)Noise Ratio | - |
| STA | Station | Any 802.11 device (AP is also a STA). |
| STBC | Space-Time Block Coding | TX diversity (Alamouti). |
| TBTT | Target Beacon Transmission Time | Scheduled beacon instant. |
| TDLS | Tunneled Direct Link Setup | STA↔STA direct path (11z). |
| TID | Traffic Identifier | 0-7 UP → maps to 4 ACs. |
| TIM | Traffic Indication Map | Buffered-unicast bitmap in beacon. |
| TPC | Transmit Power Control | 11h power management. |
| TSF | Timing Synchronization Function | 64-bit µs BSS clock in beacons. |
| TWT | Target Wake Time | Negotiated wake schedules - see Power Save sheet. |
| TXOP | Transmit Opportunity | Time-bounded medium ownership per AC. |
| U-APSD | Unscheduled Automatic Power Save Delivery | WMM-PS trigger/delivery model. |
| UORA | UL OFDMA Random Access | Contention inside RA-RUs. |
| UP | User Priority | 802.1D priority 0-7. |
| U-SIG | Universal SIGNAL field | EHT preamble field replacing HE-SIG-A, forward-compatible. |
| WMM | Wi-Fi Multimedia | WFA cert of EDCA QoS. |
| WPA2/WPA3 | Wi-Fi Protected Access | WFA security certs over 802.11i/RSN. |
| WUR | Wake-Up Radio | 802.11ba µW companion receiver. |