OFDMA Random Access Contention Period NAV Setting

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Solution Overview

Problem

The IEEE 802.11ax standard lacks specifications for how stations access the channel during the OFDMA Back-off mechanism, leading to inefficiencies in frequency spectrum utilization and throughput.

Innovation Solution

A wireless local area network communication method where stations receive a message frame with an OFDMA random access contention period field, allowing them to set their network allocation vector idle and contend for the channel within a designated period, ensuring correct NAV setting and efficient application of the UL OFDMA mechanism by allocating bandwidth resources directly from the access point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the OFDMA Back-off mechanism is implemented without specified channel access rules, then the UL OFDMA mechanism can be applied, but the frequency spectrum utilization efficiency deteriorates due to incorrect NAV setting and channel access conflicts

Engineering Contradiction:
Improvesystem throughputVSAvoidfrequency spectrum utilization efficiency
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent introduces a new parameter 'OFDMA random access contention period' in the trigger frame, which changes the channel access mechanism from traditional DCF to a controlled random access mode. This parameter allows STAs to set their NAV correctly and determines when they can contend for channel access, resolving the NAV setting conflict and improving spectrum utilization efficiency while maintaining system throughput.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If stations set NAV to idle continuously to allow channel access, then channel access flexibility improves, but interference increases due to uncoordinated access attempts

Engineering Contradiction:
Improvechannel access flexibilityVSAvoidinterference
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent implements periodic channel access control by defining a specific 'OFDMA random access contention period' during which STAs are allowed to set NAV to idle and contend for channel access. Outside this period, STAs maintain NAV in busy state. This periodic mechanism provides controlled flexibility while preventing continuous interference from uncoordinated access attempts.

Inventive Principle:
Principle #19Periodic action

3Adaptability or versatility

If the OFDMA random access contention period is extended to allow more stations to access the channel, then channel access opportunity increases, but the channel occupancy time for scheduled transmissions decreases

Engineering Contradiction:
Improvechannel access opportunityVSAvoidchannel occupancy time
Core Design Contradiction:
Adaptability or versatilityVSDuration of action of moving object

Solution Approach 1:

The patent allows only a portion of STAs (those with random back-off counter equal to 0) to access the channel during the OFDMA random access contention period, rather than allowing all STAs to contend simultaneously. This partial action approach provides sufficient channel access opportunities for uplink data while preserving adequate channel occupancy time for scheduled downlink and uplink transmissions.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3399813B1Wireless local area network communication method and communication device, and site
Publication Date: 2024.05.15 MEIZU TECH CO LTD
  • EP3399813B1 patent drawingFigure 1~3
  • EP3399813B1 patent drawingFigure 4~5

AI summary

The present invention provides a wireless local area network communication method and communication device, and a station. The wireless local area network communication method comprises: receiving a message frame sent by an access point with a station which supports a UL OFDMA mechanism, wherein the message frame contains an OFDMA random access contention period field, and the OFDMA random access contention period field indicates that the station is capable of contending for accessing a channel within a contention period indicated by the OFDMA random access contention period field; and setting a network allocation vector to be idle within the contention period indicated by the OFDMA random access contention period field with the station, wherein the station has been allocated with a bandwidth resource. The technical solution of the present invention realizes correct setting of an NAV by the station and ensures that a UL OFDMA mechanism is applied, thereby improving the utilization efficiency of a frequency spectrum, and indirectly improving the throughput of the system.