Access Point RTS Error Recovery for Downstream Throughput

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Solution Overview

Problem

Existing computer networking systems face reduced downstream network throughput due to collisions and interference from hidden nodes, which are not effectively addressed by current RTS/CTS handshaking protocols, leading to increased backoff times and channel access losses.

Innovation Solution

The access point decodes RTS frames based on symbol error sequences and utilizes self-CTS frames during RTS reception failures to seize transmit opportunities, prioritizing voice packets and minimizing collision impact, thereby converting missed upstream transmit opportunities into downstream transmit opportunities without channel contention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RTS/CTS handshaking is implemented to overcome hidden node problem, then collision avoidance is improved, but backoff time and channel access loss increase

Engineering Contradiction:

Improvecollision avoidanceVSAvoidbackoff time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent converts the harmful effect of RTS frame errors into a beneficial transmit opportunity. When RTS frame errors occur, instead of discarding the opportunity, the system seizes the transmit opportunity during RTS reception failure, converting what would be wasted time into productive downstream transmission time, thereby improving throughput while maintaining collision avoidance benefits

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system performs preliminary decoding of RTS frames based on symbol error sequences and station database before complete reception. This preliminary action allows the access point to identify and seize transmit opportunities earlier in the process, reducing the effective backoff time while maintaining reliable collision avoidance through the preliminary decoding check

Inventive Principle:

Principle #10Preliminary action

2Reliability

If RTS/CTS flow control is used to reduce collisions, then packet collision is reduced, but overhead increases and may cancel benefits

Engineering Contradiction:

Improvepacket collision reductionVSAvoidprotocol overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and utilizes only the beneficial portion of RTS frames even when errors occur. By decoding RTS frames based on symbol error sequences and extracting transmit opportunities from erroneous frames, the system removes the overhead burden while retaining the collision avoidance benefit, effectively separating the useful function from the harmful overhead

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If stations perform backoff after RTS collision, then collision avoidance is improved, but downstream throughput decreases

Engineering Contradiction:

Improvecollision avoidanceVSAvoiddownstream throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent inverts the traditional approach by having the access point seize transmit opportunities during RTS reception failures rather than waiting for stations to complete backoff. This reversal converts station backoff time into access point transmission opportunities, maintaining collision avoidance while dramatically improving downstream throughput

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11057932B2Increasing downstream network throughput from access points in data communication systems using transmit opportunities from RTS (request to send)frame errors

Publication Date: 2021.07.06 FORTINET INC

AI summary

A sender of the RTS frame is decoded based on the symbol error sequence and a station database within the access point, even if there is a CRC (cyclical redundancy checking) failure. The access point seizes the transmit opportunity during RTS reception failure, as collision results in higher back off window before stations can transmit. To minimize the impact of collision on voice clients, some embodiments prioritize transmission of voice packets within the new transmit opportunity.