Network allocation vector¶
A per-station duration state that virtually reserves a shared wireless medium.
Core Idea¶
A network allocation vector (NAV) is a wireless station's virtual carrier-sense duration state. When a relevant frame announces the time anticipated for another exchange, the station maintains a remaining busy interval and defers while it is nonzero. NAV is a protocol prediction, not direct measurement of radio energy. When it reaches zero, the virtual hold ends, but physical sensing and other MAC rules may still block transmission.
A conceptual station hears an exchange-duration announcement and waits rather than treating a quiet moment as free channel access. An IEEE 802.11 working-group RTS/CTS document describes stations maintaining NAV from duration fields during a subsequent exchange, a real standard-design use rather than a fabricated packet trace. Physical carrier sensing is the nearest miss because it reports current energy, not a frame-announced future interval. Generic reservation ideas can travel, but NAV specifically depends on wireless frame interpretation and per-station state. It neither allocates network addresses nor guarantees collision-free access.
Scope of Application¶
These uses keep frame-announced duration and station-local deferral explicit.
- Wireless MAC design. Coordinate shared-medium deferral from duration announcements.
- Protocol interpretation. Distinguish virtual and physical busy indications.
- Packet-trace analysis. Explain why a station waits despite weak current energy observation.
- Standards education. Relate RTS/CTS duration fields to local station state without assuming universal deployment.
Clarity¶
Name the receiving station, duration announcement, local countdown and deferred transmission. Physical carrier sensing is the nearest miss. Distinguish the frame field from the state it sets, and zero NAV from unconditional permission to send.
Manages Complexity¶
A shared channel can appear quiet during a planned multi-frame exchange. NAV compresses an announced future busy interval into a local countdown so each station need not infer every hidden exchange from instantaneous energy. That prediction can be stale or incomplete, which is why physical carrier sense and other MAC conditions remain separate. The state is a coordination aid, not an absolute collision-prevention guarantee.
Abstract Reasoning¶
- Identify a shared wireless contention domain.
- Read the duration announcement in a relevant frame.
- Track the station's remaining virtual busy interval.
- Defer while NAV remains nonzero under the MAC rule.
- At expiry, reassess physical channel state and other access constraints.
Knowledge Transfer¶
The idea of an announced reservation causing temporary local deferral may apply to other shared resources. But a calendar reservation is not a NAV without wireless frame duration and per-station carrier-sense state. Neither physical sensing nor generic resource allocation strictly subsumes the protocol mechanism's whole identity.
Neighborhood in Abstraction Space¶
Network allocation vector sits in a crowded region of the domain-specific corpus (39th percentile for distinctiveness): several abstractions share nearly its structure, so a description that fits it tends to fit its neighbors too.
Family — Queueing, Networks & Concurrent Systems (9 abstractions)
Nearest neighbors
- Reachability analysis — 0.89
- Automated Communication System — 0.89
- Routing — 0.87
- Time-sharing — 0.87
- Global network positioning — 0.87
Computed from structural-signature embeddings · 2026-10-08