WLAN Deferral Policies for OBSS Throughput

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Solution Overview

Problem

Current wireless communication systems face challenges in managing communication deferral policies, particularly in dense networks where RTS/CTS messages can lead to over-suppression, resulting in poor throughput due to frequent deferral caused by detecting messages from overlapping basic service sets (OBSS), which hampers carrier sense multiple access (CSMA) efficiency.

Innovation Solution

The implementation of enhanced RTS/CTS messages that include BSS identifier (BSSID) information and device type indicators, allowing wireless devices to differentiate between in-BSS and OBSS messages, enabling selective deferral policies based on signal strength, device type, and other conditions, thereby allowing increased reuse and improving network throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If devices defer communications upon detecting RTS/CTS messages from OBSS, then hidden node problems are reduced, but network throughput deteriorates due to over-suppression and frequent deferrals

Engineering Contradiction:
Improvehidden node mitigationVSAvoidnetwork throughput
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by differentiating deferral behavior based on the specific characteristics of received messages. Devices examine message types (RTS, CTS, data), BSSID matching, and signal strength to determine whether to defer. This selective approach allows deferral only when necessary (e.g., when BSSID matches own BSS or signal strength exceeds threshold) while permitting transmission in other cases, thus maintaining hidden node protection where needed while improving throughput by avoiding unnecessary deferrals.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If devices always defer to OBSS transmissions, then interference is reduced, but channel reuse efficiency deteriorates

Engineering Contradiction:
Improveinterference reductionVSAvoidchannel reuse efficiency
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent employs parameter changes by introducing multiple decision parameters for deferral determination: message type (RTS/CTS/data), BSSID match status, signal strength thresholds, and device type indicators. By dynamically evaluating these parameters rather than applying a fixed deferral rule, the system adapts interference management to specific conditions, reducing interference when necessary while maximizing channel reuse when the channel is safe to use.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If RTS/CTS messages are transmitted frequently, then carrier sense multiple access efficiency is improved, but deferral frequency increases causing throughput to decrease

Engineering Contradiction:
ImproveCSMA efficiencyVSAvoidthroughput
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent applies partial action by implementing selective deferral rather than universal deferral. Devices perform partial deferral based on message evaluation - deferring only for specific message types from specific sources under specific conditions. This partial approach maintains CSMA efficiency by still responding to relevant RTS/CTS messages while avoiding excessive deferral that would occur with blanket deferral policies, thus preserving throughput.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3292731B1Communication deferral policies in WLAN to increase reuse
Publication Date: 2019.10.02 QUALCOMM INC
  • EP3292731B1 patent drawingFigure 1
  • EP3292731B1 patent drawingFigure 2
  • EP3292731B1 patent drawingFigure 3

AI summary

A method, an apparatus, and a computer-readable medium for wireless communication are provided. The apparatus is configured to determine a communication deferral policy within a BSS associated with the apparatus. The apparatus is configured to receive a message from a second wireless device. The apparatus is configured to determine a message type of the message. The apparatus is configured to determine whether the message is associated with an OBSS based on the determined message type. The apparatus is configured to determine whether to defer communications based on the communication deferral policy, the message type, and whether the message is associated with the OBSS.