DSL Low Power Mode Synchronization Tone Allocation
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Solution Overview
Problem
Current DSL systems face challenges in power saving, particularly during low bit rate or idle periods, as existing low power modes can cause unstable connections and performance issues due to crosstalk and non-stationary noise when transitioning back to full power, and conventional approaches may limit power saving or cause compatibility problems with vectoring.
Innovation Solution
The implementation of a low power mode that uses more tones and power for synchronization symbols during low power operation to maintain channel estimation and reduce crosstalk, allowing for seamless transitions between low and normal bit rates without impacting other lines, and excluding unnecessary subcarriers to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional low power mode is used to reduce transmit power during low bit rate operation, then power consumption is reduced, but connection stability deteriorates due to non-stationary behavior and crosstalk variations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the transmit power level based on the operational state. When transitioning from low power mode to normal operation, the system changes the power parameter gradually rather than abruptly, preventing sudden crosstalk variations that would otherwise cause connection instability. This allows the system to maintain both power efficiency and connection reliability.
Solution Approach 2:
The patent implements preliminary action by performing channel estimation and monitoring procedures before actually transitioning out of low power mode. The system prepares the communication channel in advance by exchanging monitoring symbols and updating channel state information, ensuring that when full power is restored, the connection remains stable without sudden performance degradation.
2Use of energy by moving object
If transmit power is reduced in low power mode, then power consumption decreases, but channel estimation accuracy deteriorates leading to performance issues when returning to normal operation
Solution Approach 1:
The patent applies periodic action by implementing regular channel estimation and monitoring cycles even during low power mode operation. The system exchanges monitoring symbols at periodic intervals to maintain up-to-date channel state information without requiring full transmit power continuously. This periodic monitoring ensures channel estimation accuracy is maintained while minimizing overall power consumption.
Solution Approach 2:
The patent uses an intermediary approach by introducing dedicated monitoring symbols as a mediator between full-power data transmission and low-power states. These monitoring symbols carry channel estimation information and are exchanged at reduced power levels, allowing the system to maintain channel knowledge without the full power requirements of normal data transmission, thus balancing power consumption and estimation accuracy.
3Measurement precision
If all subcarriers are transmitted during low power mode to maintain channel estimation, then channel knowledge is preserved, but power saving is limited
Solution Approach 1:
The patent applies the extraction principle by selectively removing unnecessary subcarriers from transmission during low power mode while retaining only those subcarriers needed for essential channel estimation and monitoring functions. The system identifies and extracts the minimum necessary subset of subcarriers that maintain adequate channel knowledge, thereby significantly reducing power consumption compared to transmitting all subcarriers continuously.
Solution Approach 2:
The patent implements partial action by performing channel estimation with a partial set of subcarriers rather than all subcarriers during low power mode. The system uses a subset of subcarriers that provides sufficient channel information for maintaining connection stability, accepting that not all channel characteristics are perfectly tracked. This partial monitoring approach achieves an optimal balance between power consumption and channel estimation capability.
Data Source
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AI summary
Devices and methods are provided utilizing a low power mode. In some cases, bit loading required to provide a needed bit rate may be calculated by a receiver and sent to a transmitter. In some embodiments, a number of tones used for synchronization symbols may be higher than a number of tones used for data symbols in a low power mode. Other techniques are also presented.