Receiver Noise Variance Estimation via Antenna Decoupling
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Solution Overview
Problem
Existing digital receivers face inefficiencies in noise variance estimation due to bandwidth usage in pseudo-noise sequence insertion and limited applicability in channels with long impulse response or Doppler shift, and reliance on frequent pauses in communication streams.
Innovation Solution
Decoupling the antenna from the receiver for calibration, using an antenna equivalent load to measure input signal power and calculate receiver noise figure, which is then updated during operation based on temperature and amplifier gain measurements, allowing for regular noise variance estimation without interrupting the signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pseudo-noise sequences are inserted into the communication stream for noise variance estimation, then the receiver can calculate noise variance, but bandwidth is consumed and the method fails on channels with long impulse response or Doppler shift
Solution Approach 1:
The patent extracts the noise measurement function from the communication data stream by utilizing idle time periods where no signal is transmitted. Instead of inserting pseudo-noise sequences into the data stream, the system measures noise during gaps between transmissions, thereby eliminating bandwidth consumption while maintaining noise estimation capability
Solution Approach 2:
The patent introduces an intermediary approach by using the idle time periods as a mediator between signal transmission and noise measurement. These idle periods serve as a natural window for noise estimation without requiring additional signaling or bandwidth allocation
2Quantity of substance
If pauses between messages are used to measure receiver noise variance, then bandwidth is saved, but the method has limited applicability since it relies on frequent pauses
Solution Approach 1:
The patent enhances universality by making the noise estimation method applicable to various communication scenarios including those without frequent pauses. The system can operate in continuous transmission modes by using other mechanisms (such as pilot signals or scheduled calibration periods) to create measurement opportunities, thereby adapting to different communication protocols and traffic patterns
3Measurement precision
If the antenna is decoupled from the receiver for calibration, then accurate noise variance estimation is achieved, but signal transmission is interrupted
Solution Approach 1:
The patent implements periodic calibration where the antenna is decoupled at scheduled intervals rather than continuously. This allows the system to maintain accurate noise variance estimates through periodic measurements while minimizing signal interruption time. The calibration occurs in short bursts during naturally occurring idle periods or between data transmissions
Solution Approach 2:
The patent performs preliminary noise variance estimation during idle periods before actual data transmission begins. This allows the receiver to have noise variance values ready for use when signal processing starts, reducing the need for frequent interruptions during active transmission
Data Source
AI summary
A system according to one embodiment includes an automatic gain control circuit configured to provide an amplifier gain value; a temperature sensing circuit configured to provide a temperature; an antenna switching circuit configured to decouple an antenna from the receiver during a noise figure calibration interval; a signal power measurement circuit configured to measure input power to the receiver; a noise figure estimation circuit configured to estimate a receiver noise figure during the noise figure calibration interval based on an initial receiver noise variance, the temperature and the amplifier gain value, wherein the initial receiver noise variance is estimated based on the measured input power during the noise figure calibration interval; and a noise variance tracking circuit configured to calculate updated estimates of the receiver noise variance, wherein the updated estimates are based on updates of the measured temperature and updates of the measured amplifier gain.