WLAN Rate Adaptation via Dynamic Thresholds

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Solution Overview

Problem

Existing rate adaptation schemes for IEEE 802.11 WLANs are not adequately dynamic to quickly adapt to fluctuations in channel conditions, and many require modifications to the standard or assume symmetrical channel conditions.

Innovation Solution

A flexible rate adaptation algorithm that adjusts data transmission rates based on channel conditions using an adaptive rate algorithm with a searching mode and a transmission mode, employing a binary search method for threshold settings and an additive increase-multiplicative decrease mechanism to dynamically update success and failure thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If existing rate adaptation schemes (ARF) are used, then implementation is simple without standard modifications, but the system cannot react quickly to fluctuations in channel conditions

Engineering Contradiction:

Improveease of implementationVSAvoidresponse speed to channel changes

Core Design Contradiction:

Ease of operationVSSpeed

Solution Approach 1:

The patent implements dynamic threshold adjustment where the success and failure thresholds are not fixed but adapt based on current transmission conditions. The thresholds vary based on data rate, channel conditions, and transmission history, allowing the system to respond quickly to channel fluctuations while maintaining implementation simplicity through automated threshold adaptation rather than complex manual configuration

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of threshold values dynamically based on transmission rate and channel conditions. Different thresholds are applied for different data rates (e.g., higher thresholds for higher rates), and thresholds are adjusted based on whether transmissions are successful or failed, enabling quick adaptation to changing channel conditions without requiring standard modifications

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If fixed thresholds are used in ARF schemes, then the algorithm is simple to implement, but it cannot adapt dynamically to varying channel conditions

Engineering Contradiction:

Improvealgorithm complexityVSAvoidadaptability to channel conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent transforms fixed thresholds into dynamic thresholds that automatically adjust based on transmission rate and channel conditions. The success threshold and failure threshold are calculated differently for higher data rates versus lower data rates, and they evolve based on transmission history, providing dynamic adaptation without requiring complex external control mechanisms

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The algorithm performs self-adjustment of thresholds based on its own transmission results. By monitoring successful and failed transmissions and automatically updating thresholds based on this feedback, the system adapts to channel conditions without requiring external intervention or complex configuration, maintaining relative simplicity while achieving adaptability

Inventive Principle:

Principle #25Self-service

3Device complexity

If single failure threshold is used, then the scheme is simple, but it cannot distinguish between different channel conditions (high and low Doppler spread)

Engineering Contradiction:

Improvethreshold configuration complexityVSAvoidchannel condition detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies different threshold values for different local conditions (different data rates and channel conditions). Instead of a single universal threshold, the system uses rate-dependent thresholds and adapts thresholds based on whether the channel exhibits high or low Doppler spread characteristics, allowing precise detection and response to different channel conditions

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes threshold parameters based on detected channel conditions and transmission rate. The success and failure thresholds are adjusted according to the data rate being used and the observed transmission patterns, enabling the system to distinguish between different channel conditions (such as high versus low Doppler spread) and respond appropriately

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8155095B2Wireless LAN data rate adaptation

Publication Date: 2012.04.10 STMICROELECTRONICS INT NV

AI summary

A WLAN communication system and algorithm that adaptively changes the data transmission rate of a communication channel based on changing channel conditions. The WLAN communication system or algorithm has two modes being a searching mode and a transmission mode. Furthermore, the WLAN communication system or algorithm incorporates an additive increase, multiplicative decrease (AIMD) function into the rate adaptation algorithm.