DRU Long Training Field Layout for Interleaved Tone Allocation

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Solution Overview

Problem

Existing wireless local area network (WLAN) systems face inefficiencies in peer-to-peer traffic management and channel utilization, particularly in 802.11ac and 802.11n modes, due to limited channel bandwidth and resource allocation mechanisms.

Innovation Solution

Implementing a distributed resource unit (DRU) allocation system where non-AP stations receive a trigger frame with a DRU index value, determining a DRU allocation and interleaved tone distribution plan, and transmitting a DRU long training field (LTF) sequence based on an extremely high throughput (EHT)-LTF sequence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If distributed resource unit (DRU) allocation is implemented with interleaved tone distribution, then channel utilization and bandwidth efficiency are improved, but system complexity and difficulty of implementation increase

Engineering Contradiction:

Improvechannel utilizationVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the frequency spectrum into distributed resource units (DRUs) with interleaved tone distributions. Each DRU contains non-contiguous subcarriers that are strategically distributed across the channel bandwidth, allowing parallel transmissions to occur simultaneously without interference. This segmentation enables multiple stations to utilize different portions of the spectrum efficiently, thereby improving channel utilization while maintaining manageable system complexity through structured resource allocation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a hierarchical resource allocation structure where DRUs are nested within broader resource units (RUs). The interleaved tone distribution creates a nested pattern where subcarriers are distributed within DRUs, which are themselves distributed within the overall channel bandwidth. This nested organization allows for scalable resource management and simplifies the implementation complexity by providing a structured framework for resource allocation.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Ease of operation

If DRU allocation with interleaved tones is used, then peer-to-peer traffic management is improved, but device complexity and implementation difficulty increase

Engineering Contradiction:

Improvepeer-to-peer traffic managementVSAvoidimplementation difficulty

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent employs preliminary action by pre-configuring DRU allocations and interleaved tone distributions before peer-to-peer traffic transmission begins. The access point establishes the resource allocation framework in advance, assigning specific DRUs to different stations with predetermined interleaved patterns. This preliminary setup simplifies subsequent peer-to-peer traffic management as stations can directly utilize the pre-established resource allocations without complex real-time negotiations, thereby improving ease of operation while managing implementation complexity.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If EHT-LTF sequence is used for DRU LTF determination, then training field efficiency is improved, but compatibility with existing systems decreases

Engineering Contradiction:

Improvetraining field efficiencyVSAvoidsystem compatibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by adapting the EHT-LTF sequence parameters to work with DRU allocations. Specifically, the LTF sequence length, subcarrier spacing, and tone distribution patterns are modified to match the interleaved DRU structure while maintaining the fundamental properties of EHT-LTF sequences. This allows the system to achieve improved training field efficiency through optimized parameter settings while preserving compatibility with existing EHT standards and devices through controlled parameter adjustments rather than fundamental changes to the LTF concept.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20260019219A1Long training field (LTF) for a distributed resource unit (DRU)

Publication Date: 2026.01.15 INTERDIGITAL PATENT HOLDINGS INC

AI summary

A non-access point (AP) station (STA) receives a trigger frame with a resource unit (RU) allocation field. Further, the RU allocation field indicates a distributed resource unit (DRU) index value, and the STA determines, based on the indicated DRU index value, a DRU allocation from a plurality of DRU allocations. Each of the plurality of DRU allocations includes a respective tone distribution plan. Tones of the determined DRU allocation and the respective tone distribution plan are interleaved with tones of one or more other tone distribution plans, of the plurality of tone distribution plans, across a distribution bandwidth. The STA determines a DRU long training field (LTF) sequence. The STA transmits a signal in the determined DRU allocation, including a physical layer (PHY) preamble including the DRU LTF. Further, each respective value of the DRU LTF sequence is transmitted on a respective subcarrier of the determined DRU allocation.