TxOP Truncation via TA and RA Address Comparison
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Solution Overview
Problem
In wireless communication systems, the truncation of transmission opportunities (TxOP) can lead to interference and packet loss due to incorrect updating of network allocation vector (NAV) timings, especially when contention-free end (CF-End) messages are misinterpreted by stations not intended to receive them, causing premature contention for the medium.
Innovation Solution
A method and apparatus that determine TxOP period truncation by comparing transmitter and receiver addresses (TA and RA) in CF-End frames with associated NAV values, allowing devices to update or reset NAV timings only when the message is intended for their network allocation vector, thereby avoiding interference and collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If devices update NAV timing upon receiving any CF-End message, then the medium access control is simplified, but interference and packet loss occur due to premature contention
Solution Approach 1:
The patent implements a feedback mechanism where the receiving device checks whether the CF-End message is intended for its network allocation vector by comparing transmitter and receiver addresses with associated NAV values. This feedback loop prevents incorrect NAV updates and ensures that devices only contend for the medium when appropriate, resolving the contradiction between simple operation and reliable medium access.
2Productivity
If CF-End messages are broadcast to all devices, then transmission efficiency is improved, but unintended devices may reset their NAV timing causing collisions
Solution Approach 1:
The patent applies local quality by making the NAV update behavior specific to each device's context. Instead of a uniform response to CF-End messages, each device locally evaluates whether the message pertains to its specific NAV by comparing addresses. This ensures that CF-End messages can be broadcast efficiently while only the intended recipient updates its NAV, preventing interference from unintended devices.
3Speed
If devices contend for medium access immediately after receiving CF-End, then response time is reduced, but packet loss increases due to timing errors
Solution Approach 1:
The patent implements preliminary action by having devices perform address comparison and verification before contending for medium access. This preliminary check ensures that devices only contend when the CF-End message is genuinely intended for their NAV, maintaining fast response times while preventing packet loss from premature or incorrect contention attempts.
Data Source
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Figure 3A~3B
AI summary
This disclosure provides systems, methods, and apparatus, including computer programs encoded on computer storage media, for improving transmission opportunity (TxOP) truncation in wireless communication. In some implementations, a transmit opportunity (TxOP) period truncation or whether to update a network allocation vector (NAV) timing based on a message that includes transmitter and receiver information (such as a transmitter address (TA) and a receiver address (RA)) may be determined. For example, a station may receive a contention-free end (CF-End) frame and determine a TxOP period truncation based on comparing a TA and an RA included in the CF-End frame with a TA and an RA included in an earlier received message (e.g., an RTS). Such information may be compared to other TAs or RAs associated with NAV timing values and the NAV timing may be set, reset, updated, or canceled based on the comparison.