HFC Node Transmit Power Optimization Under Distortion Limits
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Solution Overview
Problem
Current implementations of node circuits in hybrid fiber coax (HFC) networks do not account for transmitter distortion when determining transmit power levels, leading to suboptimal data rates due to a trade-off between transmitter distortion and receiver noise, especially at higher frequencies.
Innovation Solution
A node circuit that determines an optimal transmit power based on receiver noise and a distortion model of the transmitter circuit, allocating subcarriers to cable modems based on frequency and distance, optimizing power distribution to maximize data rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher frequencies are used for signal transmission to handle increasing traffic requirements, then network capacity and data transmission capability are improved, but transmitter distortion increases leading to suboptimal data rates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting transmit power levels based on frequency, distance, and receiver noise characteristics. The node circuit calculates optimal power levels for each subcarrier allocation, changing the power parameter to compensate for transmitter distortion at higher frequencies and maximize data rates.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing distortion models and noise characteristics before actual data transmission. The node circuit performs preliminary optimization calculations to determine the optimal power spectrum and subcarrier allocations, preparing the transmission parameters in advance to avoid real-time computation delays and ensure optimal performance.
2Reliability
If transmit power is increased to overcome receiver noise and improve data rates, then signal quality is improved, but transmitter distortion increases reducing overall efficiency
Solution Approach 1:
The patent optimizes the power parameter by calculating an optimal power spectrum that balances signal quality and distortion. Instead of using uniform or maximum power levels, the node circuit adjusts power distribution across different subcarriers based on allocated resources, receiver noise, and distortion models, achieving the best trade-off between signal quality and distortion.
Solution Approach 2:
The patent applies local quality by optimizing power levels locally for each subcarrier allocation and receiver combination. Each cable modem receives a customized power allocation based on its specific distance, noise characteristics, and allocated subcarriers, rather than applying a uniform power level to all transmissions.
3Productivity
If subcarriers are allocated to multiple cable modems to increase network utilization, then productivity is improved, but fair distribution of data rates becomes difficult to achieve
Solution Approach 1:
The patent implements local quality by providing customized subcarrier and power allocations for each cable modem. The node circuit calculates optimal allocations individually for each modem based on its specific characteristics, ensuring that each receives a fair share of network resources proportional to its needs and channel conditions, rather than using uniform allocation schemes.
Solution Approach 2:
The patent employs feedback mechanisms where the node circuit receives information about receiver noise, channel conditions, and performance metrics from cable modems. This feedback is used to continuously optimize and adjust subcarrier allocations and power levels, ensuring fair distribution while maximizing overall network utilization.
Data Source
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AI summary
A node circuit associated with a hybrid fiber coax (HFC) network is disclosed. The node circuit includes an optimizer circuit configured to process a plurality of signal-to-noise ratio (SNR) values associated with a plurality of subcarriers, respectively, associated with a set of cable modem (CM) circuits coupled to the node circuit. In some embodiments, the plurality of subcarriers comprises subcarriers that are allocated to the set of CM circuits for communication with the node circuit. In some embodiments, the optimizer circuit is further configured to determine an optimal transmit power of the node circuit, based on the plurality of SNR values and a distortion model of a transmitter circuit associated with the node circuit. In some embodiments, the distortion model defines a transmitter distortion associated with the transmitter circuit.