Doppler Measurement in WLAN Reception Modules
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Solution Overview
Problem
In wireless local area networks (WLANs), especially in IEEE 802.11 systems, the increasing number of apparatuses leads to challenges in reducing unnecessary power consumption and interference, necessitating an improvement in channel access mechanisms to efficiently manage communication, particularly in machine-to-machine (M2M) communication scenarios where many devices are present, and there is a need to accurately measure the Doppler effect and carrier frequency offset (CFO) to enhance signal quality.
Innovation Solution
A method for accurately measuring the Doppler effect by generating specific functions from signals received on consecutive subcarriers, estimating the CFO in a blind manner, and compensating the measured Doppler value in the frequency domain using an interference matrix, which reduces the complexity and performance degradation of the reception module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Doppler effect measurement and compensation methods are implemented in WLAN systems, then reception SINR is improved and communication efficiency is enhanced, but device complexity and calculation complexity increase
Solution Approach 1:
The Doppler measurement process is segmented into distinct functional blocks: a first function generator that processes received signals on two consecutive subcarriers, a second function generator that processes real and imaginary parts, and a Doppler value determiner that calculates the final measurement. This segmentation allows each block to perform a specific calculation task, reducing overall computational complexity while achieving accurate Doppler effect measurement and compensation.
2Measurement precision
If accurate Doppler measurement is performed using conventional methods, then Doppler effect can be measured, but measurement precision is insufficient and reception SINR is not improved
Solution Approach 1:
The patent implements a feedback mechanism where the measured Doppler value is used to generate a compensation signal that is applied to the received signal. The system continuously measures the Doppler effect, compensates for it, and this closed-loop feedback improves the reception SINR by eliminating the harmful Doppler shift, thereby achieving both accurate measurement and improved reliability.
3Productivity
If carrier frequency offset (CFO) and Doppler effect are not eliminated, then device operation is simpler, but communication efficiency is reduced and reception quality deteriorates
Solution Approach 1:
The patent performs preliminary action by estimating and compensating for the carrier frequency offset (CFO) before measuring the Doppler effect. The system first eliminates the CFO component from the received signal, then proceeds to measure and compensate for the Doppler effect. This preliminary CFO elimination simplifies subsequent Doppler measurement and improves overall communication efficiency by removing frequency offsets before further processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves communication efficiency by eliminating CFO and Doppler effects, reducing calculation complexity, and minimizing performance degradation, thereby enhancing the signal-to-interference-plus-noise ratio (SINR) in WLAN systems.
Implementation Method 1
an object of the present invention is to accurately measure the Doppler effect at a reception module
Implementation Method 2
Another object of the present invention is to improve a reception SINR (signal to interference plus noise ratio) by eliminating the measured Doppler effect from a received signal
Implementation Method 3
A further object of the present invention is to improve communication efficiency by eliminating a CFO (carrier frequency offset) effect and the Doppler effect from a received signal
Data Source
AI summary
Disclosed is a Doppler measurement method comprising: generating a first function defined by reception signals in two consecutive subcarriers for a specific OFDM symbol; generating a second function defined on the basis of the signs and sizes of a real part and an imaginary part of the first function; repeatedly performing a process of generating the first function and the second function for all of a set of OFDM symbols; and determining, as a Doppler value, the phase of a third function obtained by adding the results of repeatedly performing the process.