DSL Transmitter Power Allocation via Water-Filling Algorithm
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Solution Overview
Problem
As DSL systems expand bandwidth, loss becomes steeper, making flat Power Spectral Density (PSD) inefficient due to non-optimal power allocation across frequencies, particularly in Twisted Metallic Pair (TMP) channels, which have negligible frequency response variability over time.
Innovation Solution
A fast converging analytical water-filling algorithm is developed to determine optimal transmission powers for each channel by calculating a function that balances power allocation across tones, considering channel gains and noise levels, and iteratively adjusting powers to satisfy specific criteria, thereby minimizing complexity and maximizing channel capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat Power Spectral Density (PSD) is used for power allocation across frequencies, then the implementation is simple, but the efficiency of data transmission deteriorates due to non-optimal power allocation
Solution Approach 1:
The patent applies water-filling power allocation that dynamically adjusts transmission power across different frequency channels based on channel conditions. Instead of using flat PSD, the system calculates optimal power distribution by considering channel gain variations, thereby improving transmission efficiency while maintaining manageable complexity through an analytical solution.
2Productivity
If bandwidth of DSL systems is expanded, then channel capacity increases, but loss becomes steeper making power allocation less efficient
Solution Approach 1:
The patent implements frequency-selective power allocation where different power levels are assigned to different frequency channels based on their individual characteristics. The water-filling algorithm identifies channels with better conditions and allocates more power to them, while reducing power to channels with steeper loss, thereby optimizing overall system performance across the expanded bandwidth.
3Productivity
If aggressive signal shaping is applied to TMP channels, then channel capacity may improve, but computational complexity increases
Solution Approach 1:
The patent extracts and exploits the specific characteristic that TMP channels have negligible frequency response variability over time. By removing the need to handle time-varying channel conditions, the system can use a simplified analytical water-filling solution rather than more complex adaptive algorithms, thereby reducing computational complexity while still achieving optimal power allocation for capacity improvement.
Data Source
AI summary
A method and apparatus for transmitting data from a transmitter device to one or more receiver devices, each of the one or more receiver devices being connected to the transmitter device via a respective wire connection, the transmitter device being operable to transmit signals onto the wire connections over one or more different channels, the method comprising, for each of the one or more different channels: determining a value of a function S˜<sup2>m</sup2>j,j, dependent on an upper bound for a channel capacity of the one or more channels and a channel gain of the jth channel; determining a transmission power Smj,j, for transmitting data along that channel based on S˜<sup2>m</sup2>j,j; and transmitting, by the transmitter device, data over that channel to one or more of the receiver devices, the data being transmitted at the transmission power Smj,j determined for that channel.