OFDMA Tone Allocation Avoiding DC Straddling

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Solution Overview

Problem

Current Wi-Fi systems, particularly in the IEEE 802.11ax standard, face issues with downlink multiuser MIMO reception jamming and lack of channel reservation, leading to lower throughput for long packets due to incorrect channel status assumptions, and OFDMA experiences reception jamming without clear channel assessment.

Innovation Solution

The implementation of OFDMA tone allocation designs with fixed locations that do not straddle DC, using longer symbol durations and flexible resource block allocations, optimizing bandwidth use, and minimizing configurations to support multi-user operations in high-density deployments, while reusing existing 802.11 architectural blocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If OFDMA allocations straddle DC to maximize bandwidth utilization, then bandwidth use is optimized, but reception jamming occurs and channel status assessment becomes inaccurate

Engineering Contradiction:

Improvebandwidth utilizationVSAvoidchannel status assessment accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent extracts the problematic DC subcarrier from the OFDMA allocation and creates a DC-free allocation scheme. By removing the DC component from the resource allocation and designing allocations that explicitly avoid straddling DC, the system eliminates reception jamming while maintaining efficient bandwidth utilization through alternative allocation patterns.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the frequency spectrum into distinct allocation regions that do not cross the DC boundary. By creating separate resource unit allocations on either side of DC rather than allowing continuous allocations to straddle it, the system prevents reception jamming while still achieving high bandwidth utilization through optimized segment distribution.

Inventive Principle:

Principle #1Segmentation

2Productivity

If channel assessment is performed without clear channel assessment mechanism in OFDMA, then multi-user operations can proceed, but reception jamming occurs leading to lower throughput

Engineering Contradiction:

Improvemulti-user operation capabilityVSAvoidreception jamming

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements preliminary channel assessment through clear channel assessment (CCA) mechanisms before OFDMA transmissions begin. By performing CCA to detect whether the channel is clear before allocating resources and initiating multi-user transmissions, the system prevents reception jamming while enabling reliable multi-user operations.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If downlink multiuser MIMO operates without channel reservation, then system complexity is reduced, but throughput decreases due to incorrect channel status assumptions

Engineering Contradiction:

Improvechannel reservation mechanismVSAvoidthroughput for long packets

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent implements channel reservation as a preliminary action before downlink multiuser MIMO transmissions. By reserving channels and performing assessments in advance, the system ensures accurate channel status information is available, preventing throughput degradation from incorrect assumptions while maintaining manageable system complexity through structured reservation protocols.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9571256B2Systems, methods, and devices for allocating OFDMA subchannels without straddling direct current

Publication Date: 2017.02.14 INTEL CORP

AI summary

Example systems, methods, and devices for reusing one or more architectural building blocks of IEEE 802.11 n/ac/ah network, and allocating one or more Orthogonal Frequency-Division Multiple Access (OFDMA) tones such that the one or more OFDMA allocations have fixed locations which do not straddle DC are disclosed.