Coordinated OFDMA AP Synchronization for Dense Wi‑Fi Interference

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Solution Overview

Problem

High-density wireless networks face challenges with increased channel contention and interference due to the limited number of non-overlapping channels, unplanned channel selection, and deployment of APs with factory default parameters, which hinder efficient data transmission and latency in environments with devices like VR/AR devices.

Innovation Solution

Implementing Coordinated Orthogonal Frequency Division Multiple Access (C-OFDMA) with synchronized data transmissions and orthogonal time/frequency resource assignment among APs, utilizing omnidirectional and directional antenna patterns to minimize latency and interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple APs are deployed in high-density networks, then network coverage is improved, but channel contention and interference increase

Engineering Contradiction:

Improvenetwork coverage areaVSAvoidchannel contention and interference

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent segments the available frequency spectrum into multiple orthogonal subcarriers and divides time into structured transmission periods (synchronization periods and C-OFDMA periods). This segmentation allows multiple APs to transmit simultaneously on different frequency resources without interfering with each other, thus maintaining network coverage while reducing channel contention and interference in high-density deployments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic transmission structures with defined synchronization periods and C-OFDMA periods. During synchronization periods, APs transmit synchronization signals at regular intervals to maintain timing alignment. During C-OFDMA periods, data transmission occurs in structured frames with predetermined resource allocations. This periodic action reduces random channel contention and interference by replacing ad-hoc transmissions with scheduled, predictable patterns.

Inventive Principle:

Principle #19Periodic action

2Ease of operation

If traditional wireless networks are used, then device connectivity is achieved, but latency increases in dense environments

Engineering Contradiction:

Improvedevice connectivityVSAvoidtransmission latency

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by establishing synchronized timing and pre-allocating orthogonal frequency-time resources before data transmission begins. APs synchronize their clocks and coordinate resource assignments in advance, so when data transmission occurs, all APs are transmitting on predetermined, non-conflicting resources. This eliminates the need for random backoff and retry mechanisms, significantly reducing latency while maintaining device connectivity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where APs exchange synchronization information and resource allocation data to coordinate their transmissions. This feedback allows APs to adjust their timing and resource usage based on network conditions, ensuring low-latency transmission by preventing collisions before they occur and enabling rapid recoordination if conditions change.

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If factory default parameters are used, then AP deployment is simplified, but resource utilization efficiency decreases

Engineering Contradiction:

ImproveAP deployment simplicityVSAvoidresource utilization efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent enables APs to automatically perform self-service functions including automatic synchronization with primary APs, automatic resource allocation based on orthogonal frequency-time codes, and automatic coordination of transmission parameters. This self-service capability allows APs to deploy with simplified default configurations while automatically optimizing resource utilization through coordinated operation, eliminating the need for manual parameter tuning while maintaining high efficiency.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12543132B2Coordinated orthogonal frequency division multiple access (C-OFDMA) in high density networks

Publication Date: 2026.02.03 CISCO TECHNOLOGY INC

AI summary

Coordinated Orthogonal Frequency Division Multiple Access (C-OFDMA) in high density networks may be provided. A primary Access Point (AP) and a subordinate AP may be caused to use an omnidirectional antenna pattern during a synchronization period. Next, the primary AP and the subordinate AP may be caused to use an omnidirectional antenna pattern during a time in which the primary AP sends a subordinate Trigger Frame (TF) during a first C-OFDMA period. The primary AP and the subordinate AP may then be caused to use a directional antenna pattern during times in which the primary AP and the subordinate AP Uplink (UL) data during the first C-OFDMA period and Downlink (DL) data during the first C-OFDMA period.