Coordinated AP TXOP Scheduling for OBSS Spatial Reuse

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Solution Overview

Problem

There is a lack of coordination between access points (APs) in wireless networks, leading to interference among overlapping basic service sets (BSSs), which limits the extent to which they can operate in proximity to one another.

Innovation Solution

Implementing a coordinated access point transmission session where multiple APs associated with different BSSs share a transmission opportunity (TXOP) by scheduling uplink or downlink transmissions with offset or aligned start times based on signal strength and interference levels, allowing concurrent packet transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If multiple APs operate independently without coordination, then each AP can autonomously manage its BSS, but interference occurs among overlapping BSSs limiting their operation in proximity

Engineering Contradiction:

Improveautonomous BSS managementVSAvoidinterference among overlapping BSSs

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Multiple independent APs are merged into a coordinated multi-AP transmission session where they share a common TXOP. The APs combine their resources and coordinate their transmissions, transforming from independent entities to a collaborative system that achieves spatial reuse while managing interference through joint scheduling.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system dynamically adjusts transmission parameters including start times, offsets, and scheduling based on real-time conditions. APs can flexibly modify their transmission behavior during the coordinated session, with start times being offset or aligned based on signal strength and interference levels, enabling adaptive interference management.

Inventive Principle:

Principle #15Dynamics

2Productivity

If APs transmit concurrently without coordination, then wireless medium utilization increases, but packet loss increases due to interference

Engineering Contradiction:

Improvewireless medium throughputVSAvoidpacket delivery success

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

APs perform preliminary actions by establishing coordination protocols and scheduling arrangements before concurrent transmissions begin. The coordinated multi-AP transmission session is set up in advance with predetermined start times, offsets, and resource allocations, allowing APs to transmit concurrently while maintaining reliability through pre-planned interference avoidance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system incorporates feedback mechanisms where APs monitor signal strength, interference levels, and transmission outcomes. This feedback is used to adjust scheduling decisions, modify start time offsets, and optimize resource allocation in subsequent transmissions, thereby maintaining both high throughput and packet delivery reliability.

Inventive Principle:

Principle #23Feedback

3Device complexity

If APs use random channel access mechanisms, then channel access is simple, but transmission efficiency is limited due to contention delays

Engineering Contradiction:

Improvechannel access mechanismVSAvoidtransmission efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

A coordinated transmission session acts as an intermediary mechanism that manages channel access for multiple APs. Instead of each AP independently contending for the channel, the coordinated session provides a structured framework for sharing the TXOP, reducing contention delays while maintaining manageable complexity through standardized coordination protocols.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If spatial reuse techniques are used without coordination, then APs can transmit in the presence of OBSS interference, but the extent of OBSS operation is limited

Engineering Contradiction:

Improvetransmission capability in OBSSVSAvoidOBSS operation flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The coordinated multi-AP transmission session provides a universal framework that enables multiple APs from different BSSs to operate together. This multi-functional approach allows the system to simultaneously achieve spatial reuse, manage interference, and support flexible OBSS operations by coordinating transmissions across multiple BSS boundaries.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP4648534A1Coordinated spatial reuse

Publication Date: 2025.11.12 QUALCOMM INC

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Figure 3A~3B

AI summary

In some implementations, a first access point (AP) selects one or more other APs for participation with the first AP in a coordinated access point transmission session. The first AP obtains a transmission opportunity (TXOP), and transmits a frame indicating scheduling information for uplink (UL) or downlink (DL) transmissions to or from the selected APs, the scheduling information indicating a respective start time for the UL or DL transmissions to or from the selected APs, at least two of the start times being offset from one another by a time period associated with decoding a preamble of a wireless packet. The first AP transmits or receives wireless packets to or from one or more associated stations (STAs) at least partially concurrently with the transmission or reception of wireless packets by the selected APs to or from their respective associated STAs based on the scheduling information.