DPDK & 802.11 — Acronym Reference

Companion to the DPDK Summit 2026 Stockholm talk

Definitions are tuned to how each term is used in this talk, not the textbook entry. For the on-deck quick reference (the terms most likely to trip up a DPDK audience), see Backup B0.

802.11 MAC mechanics

Acronym	Expansion	What it means here
A-MPDU	Aggregated MPDU	Many MPDUs concatenated into a single radio transmission. The unit of work the talk argues replaces the Ethernet frame as the operational boundary.
AC_BE	Access Category — Best Effort	The default EDCA category for normal data traffic. AIFSN=3.
AC_VI	Access Category — Video	EDCA category with shorter AIFSN (=2) and lower CWmin for latency-sensitive traffic.
ACK	Acknowledgment	Sent by the receiver SIFS after a successful frame, confirming reception.
AIFS	Arbitration Inter-Frame Space	The time a station must sense the medium idle before starting backoff. AIFS = SIFS + AIFSN × slot_time.
AIFSN	AIFS Number	The integer count of slots in the AIFS interval (3 for BE, 2 for VI).
BAW	Block Acknowledgment Window	The range of MPDU sequence numbers a receiver is currently tracking for BlockAck.
BlockAck	Block Acknowledgment	A single ACK that confirms reception of multiple MPDUs in an A-MPDU. Each MPDU's success is independent.
BSS	Basic Service Set	One AP plus its associated stations — a Wi-Fi cell. The talk argues for coordination across BSSes via the concentrator.
CCA	Clear Channel Assessment	The receiver's check that the medium is idle before transmission. Two flavors: CCA-CS (carrier sense, decoding 802.11 preambles) and CCA-ED (energy detect, total RF energy threshold).
CF-End	Contention-Free End	A control frame that explicitly terminates a contention-free period and clears NAV at receiving stations. The primitive the concentrator uses to release stations into a compete window.
CSMA/CA	Carrier Sense Multiple Access / Collision Avoidance	Wi-Fi's contention model. Every station listens before transmitting and uses random backoff to reduce collision probability.
CSMA/CD	Carrier Sense Multiple Access / Collision Detection	Ethernet's original contention model (1980s shared-bus). The protocol identity remains in 802.3 even though switched fabric made the contention parts dormant.
CWmin / CWmax	Contention Window minimum / maximum	The bounds on the random backoff range. Each station picks a random integer in [0, CW] slots before TX; CW grows on collision. The pseudocode work uses CWmin=0 to make scheduling deterministic.
DCF	Distributed Coordination Function	The original 802.11 distributed-contention mode. EDCA is its QoS-aware successor.
DIFS	DCF Inter-Frame Space	The legacy DCF equivalent of AIFS. = SIFS + 2×slot_time.
EDCA	Enhanced Distributed Channel Access	The QoS-aware contention scheme in 802.11e+. Provides four access categories (AC_BE, AC_BK, AC_VI, AC_VO) with different contention parameters.
FCS	Frame Check Sequence	The 32-bit CRC at the end of every 802.11 frame.
MAC	Medium Access Control	The Layer 2 logic that decides when and how a frame is transmitted. The talk's central claim is that today's Wi-Fi MAC lives in firmware; the architecture moves it to the host.
MLO	Multi-Link Operation	802.11be feature coordinating multiple radios for a single station/AP relationship. Coordinates links, not building-wide scheduling.
MPDU	MAC Protocol Data Unit	A single 802.11 frame at the MAC layer — what the host hands to the PHY.
NAV	Network Allocation Vector	A virtual-carrier-sense timer set from the Duration field of received frames. While NAV > 0, the station treats the medium as busy regardless of physical sensing. The mechanism Backup B10 ("NAV reset, by scope") manipulates.
OBSS	Overlapping BSS	Another BSS sharing the same channel within range. Source of inter-cell interference today.
OFDMA	Orthogonal Frequency Division Multiple Access	The 802.11ax/be feature that lets the AP schedule multiple stations on subsets of subcarriers within one transmission. Local to one AP — does not provide cross-AP scheduling.
PCF / HCF	Point Coordination Function / Hybrid Coordination Function	Legacy 802.11 modes where the AP coordinates contention-free periods. Largely abandoned commercially. The historical proof that 802.11 has always had centralized-control primitives.
PHY	Physical Layer	The Layer 1 hardware that turns bits into RF signals (and back). Stays at the antenna in the proposed split.
PPDU	PHY Protocol Data Unit	The full thing that goes on the air: preamble + PHY header + PSDU.
PSDU	PHY Service Data Unit	The MAC-layer frame (a.k.a. MPDU) that the PHY wraps in a preamble.
RTS/CTS	Request To Send / Clear To Send	Optional handshake before data, used to reserve airtime via NAV. Helps with hidden-node scenarios.
SIFS	Short Inter-Frame Space	The shortest interframe gap (16 µs in 5 GHz). Used between frames in a single TXOP exchange (e.g., DATA→ACK). The "SIFS-bounded fast path" the talk says must stay at the radio.
TSF	Timing Synchronization Function	The 802.11 microsecond-resolution timer that all stations in a BSS track. The host's TSF sync work makes this coherent across 8 RRHs.
TXOP	Transmit Opportunity	A bounded time window won via contention during which a station may transmit. The talk's "unit of work" — what the scheduler reasons about.

802.11 PHY / RF

Acronym	Expansion	What it means here
ADC / DAC	Analog-to-Digital / Digital-to-Analog Converter	The boundary between the radio's analog and digital domains.
CMOS	Complementary Metal-Oxide Semiconductor	The process technology most modern Wi-Fi silicon is built in.
CSI	Channel State Information	Per-subcarrier amplitude and phase measurements describing the radio channel between TX and RX. The same data the receiver uses to demodulate is also the input to Wi-Fi sensing (B1).
EMF	Electromagnetic Field	The physical signal Wi-Fi rides. Backup B1 makes the point that the same EMF can be used for both communications and sensing.
FBAR / BAW	Film Bulk Acoustic Resonator / Bulk Acoustic Wave	RF filter technologies in modern Wi-Fi front ends.
FEC	Forward Error Correction	Encoding that adds redundancy so receivers can recover from bit errors without retransmission.
FEM	Front-End Module	Integrated package combining PA, LNA, and switches at the antenna.
FFT / IFFT	Fast Fourier Transform / Inverse FFT	The math that converts between time-domain samples and OFDM subcarrier values. The PHY does this on every PPDU.
LBT	Listen Before Talk	Generic name for any pre-transmission medium-busy check; CSMA/CA is one form of LBT.
LNA	Low-Noise Amplifier	First-stage amplifier on receive — boosts faint signals from the antenna with minimal added noise.
MCS	Modulation and Coding Scheme	The discrete index (0–11 for HE) that names a specific modulation + coding rate combination. The host walks an MCS ladder; the PHY ARM executes the chosen index.
MIMO	Multiple-Input Multiple-Output	Using multiple antennas at TX and RX to send multiple spatial streams simultaneously.
MU-MIMO	Multi-User MIMO	One AP transmitting to multiple stations simultaneously on different spatial streams.
OFDM	Orthogonal Frequency Division Multiplexing	The modulation scheme used by 802.11a/n/ac/ax/be. Data rides multiple subcarriers in parallel.
PA	Power Amplifier	Last-stage amplifier on transmit — drives the antenna at full power.
PER	Packet Error Rate	The rate at which received frames fail FCS check. The control signal driving rate adaptation.
PLCP	Physical Layer Convergence Procedure	Legacy 802.11 PHY sublayer that wraps the MAC frame in a preamble + PHY header. The terms "PLCP preamble" and "PLCP header" still appear in older 802.11 specs and code; modern 802.11 (n/ac/ax/be) restructured this as the PPDU format.
RSSI	Received Signal Strength Indicator	A summary measurement of received power. Coarser than SNR.
SINR	Signal-to-Interference-plus-Noise Ratio	SNR in the presence of co-channel interference from other transmitters.
SNR	Signal-to-Noise Ratio	Per-subcarrier amplitude of signal vs. background noise.

DPDK & host-side

Acronym	Expansion	What it means here
AF_XDP	Address Family XDP	Kernel-bypass fast-path framework, alternative to DPDK.
DMA	Direct Memory Access	Hardware transferring memory between host RAM and the NIC without CPU involvement.
eventdev	Event Device	DPDK's abstraction for scheduling work events. The talk proposes a deadline-aware backend for TXOP scheduling.
mbuf	Message Buffer	DPDK's packet-buffer abstraction. The talk proposes an MPDU-aware mbuf type with shim-header metadata.
NIC	Network Interface Card	Generic name for the hardware adapter; in the talk, the wireless equivalent is an RRH.
PMD	Poll Mode Driver	A DPDK driver that polls the NIC for packets instead of using interrupts. The pattern Fi-Wi extends to Wi-Fi radios.
RJ45	Registered Jack 45	The 8-pin connector used for Ethernet cable termination. The image on slide 3 ("the leash gave out").
rte_mbuf	runtime mbuf	DPDK's specific implementation of the mbuf, with dynamic field metadata.

Transport / control loop

Acronym	Expansion	What it means here
AQM	Active Queue Management	A class of router/host algorithms that manage queue depth via mark or drop. CoDel, PIE, fq_codel are AQM. The talk argues L4S is not AQM in the classical sense — it's airtime-aware marking.
BBR	Bottleneck Bandwidth and Round-trip propagation time	A modern TCP variant that infers bottleneck capacity rather than reacting to loss.
CC	Congestion Control	The general class of sender-side algorithms responding to congestion signals (drops, ECN marks).
DualPI2	Dual-queue Proportional Integral controller, version 2	The reference AQM that supports L4S. Maintains two queues (classic vs. L4S) and marks the L4S queue based on a target latency.
ECN	Explicit Congestion Notification	A bit in the IP header used to signal congestion without dropping the packet. Senders react to ECN marks just as they would to drops.
L4S	Low Latency, Low Loss, Scalable throughput	A transport architecture using ECN marking before queues form, to keep latency near zero. The talk proposes Wi-Fi-aware L4S marking based on airtime, not bytes.
TCP	Transmission Control Protocol	The classic reliable transport. Reacts to packet drops by reducing send rate.

Cellular / O-RAN borrowed vocabulary

Acronym	Expansion	What it means here
C-RAN	Centralized / Cloud Radio Access Network	The cellular architectural pattern of separating baseband processing from radio heads. The architectural ancestor Fi-Wi borrows from.
CU	Centralized Unit	O-RAN's term for the upper-layer (PDCP/RRC) component. Out of scope for the talk.
DU	Distributed Unit	O-RAN's term for the upper-MAC / scheduler component. In Fi-Wi the host plays this role.
NDP	Null Data Packet	A frame with no data payload, used for sounding (beamforming feedback). The PHY ARM emits NDPs on host instruction.
O-RAN	Open RAN	An open standards effort defining cellular RAN interfaces. Source of the "Split 6" vocabulary the talk uses.
PDCP / RLC / RRC	Packet Data Convergence Protocol / Radio Link Control / Radio Resource Control	Cellular L2/L3 layers. Out of scope for the talk; mentioned only when Split 6 is discussed in context.
RRH	Remote Radio Head	The antenna-side hardware in a C-RAN. In Fi-Wi the term carries over: each RRH is a Wi-Fi PHY + tiny ARM, fronthauled to the concentrator.
Split 6	O-RAN MAC-PHY split	The MAC-PHY functional split where the lower MAC and PHY stay at the radio, and everything above migrates upstream. The implementable-today cut Fi-Wi proposes for Wi-Fi — host runs scheduling/contention/policy, radio executes SIFS-bounded fast path on a small ARM.
Split 8	O-RAN PHY-RF split	The fully-centralized split: PHY moves to the host too. Radio becomes RF only — amplifiers, filters, ADC/DAC, antenna. Raw IQ samples cross the fronthaul over 100 Gb/s+ SERDES (borrowed from cellular C-RAN, where this is operational today). The architectural endpoint for Fi-Wi: no firmware in the radio, PHY is host-side code, joint multi-radio decoding and building-scale RF coordination become possible.

Timing & coherence

Acronym	Expansion	What it means here
ppm	parts per million	Unitless rate-error measure. Used in the mt76 TSF debug instrumentation to report oscillator drift. 1 ppm ≈ 1 µs error per second.
PTP	Precision Time Protocol	IEEE 1588 — the standard for high-precision clock distribution over Ethernet. The talk's "Three places to start" slide names PTP-clock-domain bridging as a DPDK work item.
TSF	Timing Synchronization Function	(See 802.11 MAC.) The microsecond timer the host uses for cross-radio coordination.

Sensing / 802.11bf

Acronym	Expansion	What it means here
802.11bf	Wi-Fi sensing amendment	The IEEE amendment standardizing Wi-Fi sensing — using existing 802.11 measurements (CSI, channel response) to infer motion, presence, and similar physical signals. The architecture this talk proposes happens to give 802.11bf a host-visible control plane for free.

Connectors / fronthaul

Acronym	Expansion	What it means here
MMIO	Memory-Mapped I/O	The mechanism by which the host reads/writes radio registers via mapped address ranges.
MTP	Multi-fiber Termination Push-on	A multi-fiber connector used in fan-out cabling between QSFP+ and individual fiber pairs.
PCIe	Peripheral Component Interconnect Express	The host bus that carries descriptors, MPDUs, and metadata between the host and each RRH.
QSFP+	Quad Small Form-factor Pluggable Plus	The 40 Gbps optical/copper transceiver used for the fronthaul links between concentrator and RRHs.

Historical anchors (About slide context)

Acronym	Expansion	What it means here
FDDI	Fiber Distributed Data Interface	Late-1980s 100 Mbps token-ring network (NASA / ISS). On the About slide as part of the speaker's lineage.
RSM	Route Switch Module	The Catalyst 5000 module that integrated Layer 3 routing into hardware Ethernet switching (mid-1990s). The architectural ancestor of "MAC on host, PHY in silicon."

Quick reference

If someone asks “wait, what’s that?”, these are the ones to be ready to define on the fly without reaching for the sheet:

TXOP — bounded transmit opportunity, the unit the scheduler reasons about
A-MPDU — aggregated MPDUs in one radio transmission
MCS — discrete modulation/coding index, the host picks from a ladder
EDCA — QoS-aware contention scheme with four access categories
NAV — virtual carrier sense; how Wi-Fi reserves airtime via the Duration field
TSF — microsecond timer shared across stations in a BSS
L4S — low-latency transport using ECN marking before queues form
Split 6 — O-RAN's MAC-PHY split; lower MAC + PHY at the radio, everything else at the host
CSI — channel state information; per-subcarrier signal description
CF-End — control frame that explicitly clears NAV