| MLD concept | Multi-Link Device = one logical device (one MLD MAC address, one association, ONE security context) containing multiple link STAs (2.4/5/6 GHz affiliated STAs, each with own link MAC). | Upper layers see a single interface. Association/4-way happen once at MLD level; pairwise keys are MLD-level, group keys per link. RADIUS/PMK caching keyed to MLD MAC. |
| ML element (Ext 107) | Basic variant carries MLD MAC, EML capabilities, MLD capabilities + per-STA profiles of other links. ML Probe Request asks an AP for full profiles of its partner links in one exchange. | Assoc Request lists which links the client wants; Assoc Response confirms accepted links. |
| STR mode | Simultaneous Transmit & Receive: links fully independent - can TX on one while RX on another. Requires sufficient radio isolation (typically 5+6 GHz). | Highest throughput/lowest latency mode; APs are STR; premium phones/laptops STR on 5+6. |
| NSTR mode | Non-STR: link pair interferes (e.g. adjacent spectrum) - cannot TX on one while receiving on other; TX endings must be aligned. | Constraint mode for cheap radios; scheduler must sync PPDU end times. |
| EMLSR | Enhanced Multi-Link Single Radio: one full radio + low-capability listeners on other links; AP sends initial control (MU-RTS/BSRP) padded so client can switch its radio to that link, then full-rate exchange. | Gives single-radio devices MLO latency benefits (listen on 2 links, ride best one). EML capabilities advertise transition delay/padding needs. |
| EMLMR | Enhanced Multi-Link Multi-Radio: device reallocates spatial streams/RF chains across links dynamically (e.g. 2+2 → 4 on one link). | Rare in first-gen silicon. |
| TID-to-Link Mapping | Default: every TID valid on every setup link. Negotiable (Ext 109): map e.g. TID 6/7 (voice) → 6 GHz only, bulk TIDs → 5 GHz. | Traffic engineering + power save tool. Also how an AP MLD can steer without disassoc. |
| MLO power save | Per-link PM state + ML Traffic Indication in beacons; client can doze all but anchor link. | Battery devices camp on 2.4/5 anchor, burst on 6 GHz. |
| Multi-RU (MRU) | 11be allows one STA multiple RUs: small-RU combos within a 20 MHz boundary (26+52, 26+106); large-RU combos: 484+242 (80 M), 996+484 (160 M), 996+484+242, 2×996, 3×996+484, etc. (320 M). | 11ax limited each STA to ONE RU - MRU recovers punctured/fragmented spectrum for a single user. |
| Preamble puncturing | Static: EHT Operation disabled-subchannel bitmap permanently masks 20 MHz slices (incumbent/radar). Dynamic: per-PPDU puncturing signaled in U-SIG. | Lets a 320 MHz BSS survive a wedged 20 MHz slice instead of collapsing to 160. Min punctured granularity 20 MHz; primary channel never punctured. |
| 4096-QAM | MCS 12/13, needs EVM ≤ -38 dB and SNR ≈ 38+ dB. | ~20% over 1024-QAM; realistic only near-AP LoS. Marketing rates assume it everywhere. |
| 320 MHz | 6 GHz only (channels: center 31/63/95/127/159/191 style, two 320 MHz channelization sets). | US 6 GHz fits three 320 MHz channels (overlapping sets). See Channel Plans sheet. |
| R-TWT + SCS | Restricted TWT protects latency SPs; SCS (Stream Classification Service) with QoS Characteristics element tells AP flow requirements (delay bound, MSDU rate). | Wi-Fi 7 latency story = R-TWT + MRU + MLO redundancy, not just peak rate. |
| Key debug points | ML setup visible in Assoc Req/Resp ML element; per-link BSS entries share MLD; 4-way on one link installs keys for all; EAPOL M3 carries MLO GTK/IGTK KDEs per link. | Broken MLO often = client associating single-link (check ML element parse), or T2L map rejecting, or PMF/H2E prerequisites missing on 6 GHz. |