Multi-Tone Transceiver Channel Segmentation for Noise Resilience
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Solution Overview
Problem
Existing DSL modem rate adaptation methods, such as Seamless Rate Adaptation (SRA), are susceptible to noise increases that can corrupt data and lead to service disruptions, particularly in applications like video or audio, due to the vulnerability of overhead bytes containing rate adaptation messages.
Innovation Solution
A method for operating multi-tone transceivers that segregates communication channels into robust (RCC) and standard (SCC) channels, with RCC channels having higher noise margins and gain scaling, allowing for reliable transport of control information and user data, even during noise fluctuations, thereby reducing the need for retraining and maintaining continuous service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Seamless Rate Adaptation (SRA) is used for rate adaptation during showtime, then the line rate can be dynamically adjusted according to noise conditions, but the overhead bytes containing SRA messages become vulnerable to noise corruption, causing service disruptions and retraining
Solution Approach 1:
The patent segments the communication channel into two distinct parts: a robust communication channel (RCC) for transmitting control information and a standard communication channel (SCC) for user data. This segmentation allows critical control messages to be transmitted over the more noise-resistant RCC, preventing corruption while maintaining rate adaptation capabilities on the SCC.
Solution Approach 2:
The patent applies different noise margin targets to different parts of the system: higher noise margins are applied to the RCC tones used for control information, while standard noise margins are applied to the SCC tones for user data. This local differentiation ensures that control messages have enhanced protection against noise while maintaining overall system efficiency.
2Reliability
If noise margin is increased to protect against noise increases, then the robustness of control information transport is improved, but the data rate on affected tones must be reduced
Solution Approach 1:
By segmenting the channel into RCC and SCC, the patent isolates the impact of higher noise margins to only the control information tones. The user data tones on the SCC can maintain their original bit loading and data rate, so the productivity loss is minimized and confined only to the overhead bytes rather than affecting the entire data stream.
Solution Approach 2:
The patent applies higher noise margins locally only to the RCC tones carrying control information, while the SCC tones for user data maintain standard noise margins. This localized application of enhanced protection ensures that reliability is improved where needed without unnecessarily reducing the data rate across the entire system.
3Reliability
If retraining is performed to adapt to new noise conditions, then the modems can recover from noise corruption, but the process takes 10 to 30 seconds causing service disruption
Solution Approach 1:
The patent prepares for potential noise corruption in advance by transmitting control information over the pre-established robust communication channel with higher noise margins. This beforehand cushioning against noise ensures that even when noise increases occur, the control messages remain intact and no retraining is needed, thus preventing service disruption before it can happen.
Solution Approach 2:
The RCC acts as an intermediary channel that mediates the transmission of control information between the modems. By using this intermediate robust path for control messages, the system can detect and adapt to noise conditions without the control channel itself being corrupted, avoiding the need for lengthy retraining procedures.
Data Source
Figure 1~2C
Figure 3
Figure 4A~4B
AI summary
A multi-tone transceiver including: a channel controller and a plurality of components forming a transmit path and a receive path. The channel controller configured to determine bit-loading for each successive symbol or tone set based on a 1st noise margin target for a first subset of tones in each tone set dedicated to transport of a robust communications channel (RCC) and based on a 2nd noise margin target less than the 1st noise margin target for remaining tones in each tone set dedicated to a standard communications channel (SCC). The plurality of components forming the transmit and receive paths are responsive to the channel controller to select for data modulated on a given tone at least one of smaller constellations and higher gain scaling levels when the given tone corresponds to an RCC tone as compared to an SCC tone, whereby the first set of tones dedicated to the RCC exhibit greater immunity to noise variations than the remaining tones dedicated to the SCC.