Variable Resolution ADC Gain Controller for OFDM Receiver Power Optimization
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Solution Overview
Problem
Existing OFDM receivers face challenges in managing varying signal strengths due to multipath reflections and subcarrier changes in wireless environments, leading to inefficient gain control and ADC resolution settings that affect power consumption and error rates.
Innovation Solution
Implementing a variable resolution analog to digital converter (ADC) that switches between high and low resolution modes during preamble intervals and symbol changes, combined with a gain controller that adjusts receiver gain symbol by symbol based on measured power levels, ensuring optimal linear quantization and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed high resolution (12 bits) is used for ADC throughout the packet, then measurement precision is maintained, but power consumption increases
Solution Approach 1:
The ADC resolution is made dynamic by switching between high resolution (12 bits) and low resolution (10 bits) modes based on the received signal strength. During preamble and first symbol of new zones, high resolution is used for accurate measurement. During subsequent symbols with stable gain, low resolution suffices, reducing power consumption while maintaining adequate performance.
Solution Approach 2:
The ADC resolution parameter is changed based on operational phase and signal conditions. The system transitions from fixed 12-bit resolution to variable resolution (12 bits during preamble/first symbol, 10 bits during data symbols), optimizing the balance between measurement precision and power consumption.
2Device complexity
If fixed gain level is used during entire packet, then device complexity is reduced, but measurement precision deteriorates due to signal strength variations
Solution Approach 1:
The gain control is segmented into different phases: coarse gain adjustment during preamble based on signal strength measurement, and fine per-symbol gain adjustment during data transmission. This segmentation allows accurate measurement precision during critical phases while managing device complexity through structured control stages.
Solution Approach 2:
The gain controller performs preliminary gain adjustment during the preamble phase by measuring signal strength and setting an initial gain level. This preliminary action prepares the system for accurate measurement during data symbols, ensuring measurement precision is maintained when actual data transmission occurs.
3Use of energy by moving object
If ADC resolution is reduced to lower power consumption, then power consumption decreases, but reliability deteriorates due to quantization errors
Solution Approach 1:
The system dynamically adjusts ADC resolution based on signal stability. During preamble and first symbol of new zones where gain is being adjusted, high resolution (12 bits) maintains reliability. During subsequent symbols with stable gain settings, lower resolution (10 bits) is sufficient, reducing power consumption while maintaining adequate reliability through the stability of previously established gain.
Data Source
AI summary
A gain controller for a wireless communication system sets the receiver gain during the initial time duration of a preamble, and for each subsequent symbol computes a new gain value, which is applied at the end of each symbol. An analog to digital converter resolution controller sets the resolution of the ADC to a high resolution during a preamble interval and a first symbol interval, and to a comparatively lower resolution thereafter until the end of the frame. When a new zone is entered, the first symbol of the new zone is sampled at a higher resolution than the subsequent symbols.