Normalized RSSI Roaming for Wi‑Fi Transmit Power Imbalance
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Solution Overview
Problem
The received signal strength indicator (RSSI) varies due to transmit power imbalance between access points (APs) and client stations, leading to connectivity issues and data stalls, especially in low-RSSI regions where the client station's lower transmit power results in unsuccessful data transmission despite receiving strong signals from APs.
Innovation Solution
Computing a normalized received-signal strength indicator (RSSI) by subtracting the transmit power difference between APs and client stations, enabling informed roaming decisions and target AP selection to overcome power imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the access point uses high transmit power to ensure strong signal coverage, then the received signal strength at client stations is improved, but the transmit power imbalance between AP and client station worsens, leading to connectivity issues
Solution Approach 1:
The patent changes the parameter used for AP selection from raw RSSI to normalized RSSI, which accounts for transmit power differences. The client station calculates normalized RSSI by adjusting the received signal strength based on the AP's transmit power level, allowing accurate comparison across APs with different power settings and enabling reliable connection decisions despite power imbalance
Solution Approach 2:
The patent introduces normalized RSSI as an intermediary metric that mediates between the AP's transmit power and the client station's received signal strength. This intermediary parameter allows the client station to fairly evaluate and compare signals from APs with different transmit power levels, resolving the contradiction between strong signal reception and reliable bidirectional communication
2Use of energy by moving object
If the client station uses low transmit power to conserve energy, then energy consumption is reduced, but the ability to transmit data successfully to the access point deteriorates
Solution Approach 1:
The patent applies preliminary action by having the client station calculate normalized RSSI values for multiple APs before attempting data transmission. This advance calculation allows the client to select the most suitable AP that can reliably receive its low-power transmissions, preventing transmission failures and retransmissions that would waste additional energy
Solution Approach 2:
The patent changes the selection parameter from raw RSSI to normalized RSSI, which compensates for the client station's low transmit power by accounting for the AP's transmit power capability. This parameter transformation enables the client to identify APs that are most tolerant of low-power client transmissions, ensuring reliable communication while maintaining low energy consumption
3Speed
If the station selects AP based on highest RSSI without normalization, then connection speed is improved, but connectivity stability deteriorates due to transmit power imbalance
Solution Approach 1:
The patent changes the AP selection parameter from raw RSSI to normalized RSSI, which maintains the simplicity and speed of RSSI-based selection while adding power-balancing information. The normalized calculation is performed efficiently using the received signal strength and the AP's transmit power parameter, preserving fast selection speed while improving connectivity stability through more accurate AP suitability assessment
4Adaptability or versatility
If different APs use different transmit power levels according to regulatory limits, then adaptability to regulatory requirements is improved, but the ability to compare signal strength across APs deteriorates
Solution Approach 1:
The patent changes the comparison parameter from raw RSSI to normalized RSSI, which removes the effect of different transmit power levels. By dividing the received signal strength by the AP's transmit power (or subtracting in dB scale), the patent creates a standardized metric that allows accurate comparison across APs operating at different power levels permitted by regulatory requirements
Solution Approach 2:
The patent applies equipotentiality by normalizing the signal strength measurements to a common reference level. This normalization creates an equivalent comparison basis for all APs regardless of their transmit power settings, allowing the client station to fairly evaluate and compare APs from different regulatory domains or with different power configurations
Data Source
AI summary
An integrated circuit for an electronic device includes a memory and a controller. The memory stores instructions, and the controller circuitry operatively couples to the memory. Executing the instructions causes the controller circuitry to obtain a first and a second normalized RSSI, compare the first normalized RSSI with the second normalized RSSI, and select, from the first network device and the second network device, a network device associated with a greater of the first normalized RSSI and the second normalized RSSI. The first normalized RSSI includes a first difference between a first Tx power value of a first network device and an electronic device Tx power. The second normalized RSSI includes a second difference between a second Tx power value of a second network device and the electronic device Tx power.