Perceived Signal to Noise Indicator for Wireless Handoff
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Solution Overview
Problem
Current IEEE 802.11 standards lack comprehensive methods for comparative physical layer measurements across different physical layers and stations, limiting their effectiveness in network management, particularly for handoff decisions, as existing indicators like RSSI are not uniformly defined and are inadequate in high interference environments.
Innovation Solution
The introduction of a Perceived Signal to Noise Indicator (PSNI) that quantifies the perceived signal-to-noise-plus-interference ratio using demodulator internal parameters, allowing for relative and logarithmic scaling, and specification across various signal quality points to provide a more accurate and practical measure of signal quality for network management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RSSI is used as the signal quality indicator, then the measurement is simple and widely supported, but it is inadequate in high interference environments and cannot provide accurate signal quality evaluation across different physical layers and stations
Solution Approach 1:
The patent transforms the raw RSSI parameter into a new parameter PSNI by applying logarithmic scaling and normalization. This parameter transformation converts the limited dynamic range of RSSI into a more expressive scale that better represents perceived signal quality, particularly in high interference environments where RSSI values converge and lose discriminatory power.
Solution Approach 2:
The patent introduces PSNI as an intermediary parameter between the physical layer measurement (RSSI) and the network management decision layer. This intermediary parameter serves as a standardized interface that translates diverse physical layer measurements into a common metric that can be uniformly processed by higher layer protocols for handoff and load balancing decisions.
2Adaptability or versatility
If RSSI measurements are used for network management decisions, then handoff and load balancing can be performed, but the measurements from different stations and physical layers are not uniformly defined and thus not comparable
Solution Approach 1:
The patent creates PSNI as a universal measurement parameter that functions across all 802.11 physical layers (DSSS, OFDM, ERP) and all stations. The normalization process ensures that PSNI values from different stations and PHY types are on the same scale, enabling direct comparison for network management decisions without requiring PHY-specific processing.
Solution Approach 2:
The patent applies parameter transformation through logarithmic scaling and normalization to convert diverse RSSI measurements into a unified PSNI parameter. This transformation ensures that measurements from different physical layers and stations are expressed in comparable terms, resolving the non-uniformity issue while preserving the relative signal quality relationships.
3Reliability
If RSSI is used as the sole indicator, then the system is simple to implement, but it does not account for noise and interference separately, limiting its usefulness in high interference environments
Solution Approach 1:
The patent transforms the single RSSI parameter into PSNI through mathematical operations that effectively separate signal quality assessment from total power measurement. The logarithmic transformation and normalization process creates a parameter that emphasizes signal quality characteristics while downplaying the impact of absolute power levels, making it more reliable in high interference environments.
Solution Approach 2:
The patent replaces the direct use of raw RSSI measurements with a processed derived parameter PSNI. This substitution uses mathematical transformations (logarithmic scaling, normalization) to replace the simple but inadequate mechanical measurement approach with a more sophisticated calculation-based approach that better reflects perceived signal quality.
Data Source
AI summary
A wireless transmit/receive unit comprising a radio frequency signal measurement device that is configured to produce a value indicating a radio frequency signal, noise and interference received power at an antenna connector. An average noise plus interference measuring device is configured to produce a value indicating a measured average noise plus interference metric. A received signal to noise indication calculation device is configured to calculate a received signal to noise indicator from the value indicating a radio frequency signal, noise and interference received power at an antenna connector and the value indicates a measured average noise plus interference metric.