Power Allocation Threshold for Non-Gaussian Channels

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Solution Overview

Problem

Existing methods fail to optimize power allocation over parallel channels when transmitted signals are non-Gaussian, as they often rely on suboptimal waterfill policies, which are designed for Gaussian signals.

Innovation Solution

A method for allocating transmission power over parallel channels based on a channel strength threshold, calculated from estimated channel strengths and average power available, to maximize mutual information, where non-zero power is allocated to channels with strengths above the threshold and zero power is allocated to channels below it.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If waterfill policy is used for power allocation, then power allocation is simple and intuitive, but it is no longer optimal when transmitted signals are non-Gaussian

Engineering Contradiction:

Improvesimplicity of power allocation methodVSAvoidoptimality of mutual information maximization

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent changes the parameter used for power allocation from the traditional waterfill approach to a threshold-based approach that compares channel strength against a dynamically determined threshold. This parameter change enables optimality for non-Gaussian signals while maintaining computational simplicity through the use of threshold comparisons rather than complex optimization routines.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If Gaussian signals are used for transmission, then mutual information is maximized under waterfill power allocation, but Gaussian signals cannot be realized in practice due to infinite and continuous support

Engineering Contradiction:

Improvemutual information maximizationVSAvoidrealizability of signal modulation

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Instead of attempting to use Gaussian signals (which are mathematically optimal but practically unrealizable), the patent inverts the approach by developing a power allocation strategy that works optimally with practical non-Gaussian signals. The threshold-based power allocation achieves mutual information maximization for non-Gaussian signals, effectively reversing the conventional wisdom that Gaussian signals are required for optimality.

Inventive Principle:

Principle #13The other way round (Inversion)

3Loss of energy

If power is allocated to all channels regardless of strength, then power utilization is maximized, but channels with very low strength contribute negligibly to mutual information

Engineering Contradiction:

Improvepower utilization efficiencyVSAvoidmutual information contribution

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent extracts and removes the problematic allocation to very weak channels by introducing a threshold that identifies and excludes channels with insufficient strength. Channels below the threshold are assigned zero power, effectively removing them from the active communication set. This extraction approach eliminates the inefficiency of allocating power to channels that contribute negligibly to mutual information while preserving the optimality for the remaining channels.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS7489944B2Method of allocating power over channels of a communication system

Publication Date: 2009.02.10 NOKIA OF AMERICA CORP

AI summary

In one embodiment, the power for transmitting signals over at least one of a plurality of parallel channels is allocated based on a channel strength threshold and an estimated channel strength for the at least one channel. Here, the channel strength threshold is based on the estimated channel strengths for the plurality of channels.