Predictive AGC and Variable ADC Resolution for Fast Fading
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Solution Overview
Problem
Conventional wireless communication receivers face high power consumption due to the need for high precision analog to digital converters (ADCs) to compensate for dynamic range variations caused by fast fading, such as Rayleigh fading, which increases power consumption by a factor of four for each additional bit of precision required.
Innovation Solution
A system and method employing a fast predictive automatic gain control (AGC) system that uses a variable resolution ADC and a channel estimation and gain prediction circuit to minimize the dynamic range of the received signal, reducing the ADC's resolution and thereby reducing power consumption by adjusting the gain based on predicted channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ADC precision is increased to compensate for dynamic range variations caused by fast fading, then the measurement precision is improved, but the power consumption increases by a factor of four for each additional bit
Solution Approach 1:
The patent applies dynamics by making the ADC resolution variable rather than fixed. The system dynamically adjusts the ADC resolution based on predicted channel conditions and received signal power levels. When the received signal power is stable and within the optimal range, the ADC operates at lower resolution to save power. When dynamic range variations are detected or predicted, the system increases ADC resolution to maintain measurement precision. This dynamic adaptation resolves the contradiction by allowing the system to have high precision only when necessary.
Solution Approach 2:
The patent changes the parameter of ADC resolution from a fixed value to a variable parameter that can be adjusted based on channel conditions. The system uses fast predictive AGC to estimate future signal power levels and accordingly adjusts the ADC resolution parameter. This parameter change allows the system to optimize the trade-off between measurement precision and power consumption by selecting the appropriate resolution level for current and predicted channel conditions.
2Stability of the object's composition
If conventional AGC circuits are used to compensate for slow fading, then the stability is improved, but they cannot handle fast fading which requires higher ADC precision and increases power consumption
Solution Approach 1:
The patent applies preliminary action by using fast predictive AGC to estimate future channel conditions and received signal power levels before they actually occur. The system uses temporal correlation statistics and channel prediction algorithms to forecast upcoming signal variations, allowing it to proactively adjust the ADC resolution and gain settings in advance. This preliminary action enables the system to maintain stability during fast fading events without requiring excessive ADC precision, as the system is already prepared with appropriate settings before the fading occurs.
Solution Approach 2:
The patent implements feedback by continuously monitoring the received signal power and comparing it with predicted values, then using this information to adjust the ADC resolution and AGC gain. The system measures actual signal conditions, compares them with predictions, and refines its prediction model accordingly. This feedback mechanism allows the system to adapt to both slow and fast fading conditions efficiently, maintaining signal stability while minimizing power consumption by avoiding unnecessary high-resolution ADC operation.
Data Source
AI summary
A method of fast predictive automatic gain control is disclosed including estimating channel gain applied to a received signal, predicting channel gain at a subsequent time by applying temporal correlation statistics to the estimated channel gain, determining a predicted receiver gain which reduces variance between the predicted channel gain and a predetermined target power level, and applying the predicted receiver gain to the received signal. The method may include applying linear minimum mean-squared error prediction to the estimated channel gain. The method may include predicting error variance at the subsequent time by applying the temporal correlation statistics to the estimated channel gain and combining the predicted channel gain and the predicted error variance. The method may include estimating channel gain of known pilot symbols, estimating a temporal correlation function using the estimated channel gain, and determining predicted channel gain using the estimated channel gain and the estimated temporal correlation function.