Wireless Device DC Filter and Subcarrier Selection for Frequency Offset
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Solution Overview
Problem
Wireless communication devices in WLAN systems experience communication performance deterioration due to carrier frequency offset, which affects accurate measurement of noise and signal-to-noise ratio (SNR) in data signals.
Innovation Solution
A wireless communication device equipped with a DC component filter and a measurement circuit that determines a target subcarrier set based on the carrier frequency offset, allowing for accurate measurement of noise and SNR by selectively using subcarriers with minimal interference, thereby preventing performance deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If OFDM technology is used to support high transmission speed, then transmission speed is improved, but communication performance deteriorates due to mutual carrier frequency offset
Solution Approach 1:
The patent changes the measurement parameters by selecting specific subcarriers for noise and SNR measurement based on the carrier frequency offset value. When frequency offset is detected, the system switches from measuring all subcarriers to measuring only those within a valid range, thereby adapting the measurement process to the actual signal conditions and preventing performance deterioration.
2Measurement precision
If noise and SNR are measured using all subcarriers, then measurement completeness is improved, but measurement precision deteriorates due to carrier frequency offset interference
Solution Approach 1:
The patent applies local quality by treating different subcarriers differently based on their position relative to the carrier frequency offset. Instead of uniformly measuring all subcarriers, the system identifies and measures only those subcarriers that are not affected by frequency offset, giving different measurement weights to different parts of the frequency spectrum based on their reliability.
3Reliability
If DC component is removed from the received signal, then signal quality is improved, but measurement accuracy deteriorates when carrier frequency offset is present
Solution Approach 1:
The patent performs preliminary action by first detecting the carrier frequency offset before proceeding with noise and SNR measurement. This preliminary detection allows the system to identify which subcarriers are valid for measurement, ensuring that subsequent measurements are performed on unaffected subcarriers only, thereby maintaining measurement accuracy despite the presence of frequency offset.
Data Source
AI summary
A first wireless communication apparatus includes a transceiver including a direct current (DC) component filter configured to remove a DC component of a first data signal received from a second wireless communication apparatus via a channel and output a corresponding second data signal, and a measurement circuit configured to determine a target subcarrier set based on a carrier frequency offset with respect to the second data signal, and measure noise and a signal-to-noise ratio (SNR) of the second data signal using the target subcarrier set.