Access Point Power Control for Stable RSSI-Based Recalibration
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Solution Overview
Problem
Existing Auto Transmit Power Control (TPC) algorithms in wireless access points (APs) suffer from spurious and frequent fluctuations in received signal strength indicator (RSSI), leading to undesirable fluctuations in transmit power, affecting coverage and causing clients to roam or disconnect.
Innovation Solution
An algorithm that sets an initial transmit power level and maintains it unless there are changes in the AP's neighborhood, adjusting power only when RSSI changes, and terminating adjustments upon reversal of direction to stabilize power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Auto TPC algorithms continuously adjust transmit power based on RSSI changes, then transmit power adapts to neighborhood changes, but transmit power fluctuates spurious and frequently
Solution Approach 1:
The patent applies preliminary action by requiring a threshold number of consecutive RSSI changes (e.g., 3-5 changes) before triggering a transmit power adjustment. This preliminary condition filtering prevents immediate reaction to transient RSSI fluctuations, thereby stabilizing transmit power while still adapting to genuine neighborhood changes.
Solution Approach 2:
The patent implements periodic action by using fixed interval sampling of RSSI values and requiring multiple consecutive measurements showing consistent change direction before adjusting power. This periodic sampling with confirmation requirements filters out spurious single-measurement fluctuations while capturing sustained trends.
2Adaptability or versatility
If transmit power is adjusted frequently in response to RSSI changes, then coverage adapts to environment, but clients disconnect or roam frequently
Solution Approach 1:
By requiring multiple consecutive RSSI changes before power adjustment, the system preliminarily filters out transient conditions that would cause unnecessary client disconnections. This preliminary verification ensures that power changes occur only when genuine environmental changes warrant adaptation.
Solution Approach 2:
The patent applies beforehand cushioning by implementing a buffer of consecutive RSSI measurements before triggering power changes. This cushioning layer protects against spurious adjustments that would cause client instability, while still allowing genuine coverage adaptations to propagate.
3Speed
If RSSI sampling is performed continuously, then power control responds quickly to changes, but computational overhead and power consumption increase
Solution Approach 1:
The patent applies periodic action by sampling RSSI at fixed intervals rather than continuously, and by processing measurements in batches requiring N consecutive changes. This periodic approach reduces computational overhead and power consumption while maintaining adequate response speed to genuine environmental changes.
Solution Approach 2:
The patent uses partial action by requiring only a threshold number of consecutive RSSI changes (e.g., 3-5) before triggering power adjustment, rather than responding to every single RSSI change. This partial response strategy reduces processing frequency and energy consumption while still capturing meaningful trends.
Data Source
AI summary
Transmit power determination in a wireless access point (target AP) includes regularly updating receive signal strength indicators (RSSIs) associated with APs and clients in the neighborhood of the target AP. The transmit power of the target AP is recalibrated (adjusted) with each update. Recalibration continues so long as adjustments to the transmit power continue in the same direction (either increasing or decreasing) with each update. When an adjustment reversal occurs, recalibration terminates. In a variation, a final update on the transmit power, in the reversed direction, can be made prior to terminating the recalibration.