Orthogonal Pilot Matrix for WiFi Channel Estimation
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Solution Overview
Problem
In wireless local area networks using WiFi technology, especially in MIMO scenarios, the frequency deviation between stations and the access station leads to low precision in channel estimation due to the direct use of pilot coefficients for channel estimation.
Innovation Solution
Applying an orthogonal pilot matrix to the long training field (LTF) to generate a pilot signal, which is then sent on multiple subcarriers, allowing for improved channel estimation precision by determining phase deviations at the receive end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct channel estimation is performed using pilot coefficients from LTF, then the process is simple, but the channel estimation precision deteriorates due to frequency deviation
Solution Approach 1:
The patent applies an orthogonal pilot matrix to the LTF in advance to generate a pilot signal before transmission. This preliminary action embeds known pilot coefficients into the LTF, enabling the receiver to compensate for frequency deviation and improve channel estimation precision without overly increasing processing complexity
Solution Approach 2:
The patent changes the structure of the LTF by applying a pilot matrix transformation, converting ordinary LTF into a pilot signal with specific orthogonal properties. This parameter change enables frequency deviation compensation while maintaining manageable system complexity
2Measurement precision
If pilot matrix is applied to LTF to generate pilot signal, then channel estimation precision is improved, but the system complexity increases
Solution Approach 1:
The patent segments the channel estimation process by separating pilot signal generation (applying pilot matrix to LTF) from channel estimation. This segmentation allows the receiver to first extract pilot signals, compensate for frequency deviation, and then perform channel estimation, making the overall process more manageable despite increased complexity
Solution Approach 2:
The patent introduces a pilot signal as an intermediary between the LTF and channel estimation. This intermediary carries known pilot coefficients that enable frequency deviation compensation, acting as a bridge that improves estimation precision while structuring the processing flow to manage complexity
Data Source
AI summary
Embodiments of the present disclosure provide a pilot transmission method and a data transmission apparatus in a wireless local area network. The pilot transmission method in a wireless local area network in the present disclosure includes: applying a pilot matrix to an LTF to generate a pilot, and sending the pilot, where the pilot matrix includes: a matrix formed from pilot sequences each having a pilot coefficient of each of the spatial flows, where the spatial flow is on M subcarriers in N symbol periods, the pilot matrix is an orthogonal matrix, M is a positive integer multiple of L, and L is a quantity of spatial flows. According to the present disclosure, channel estimation precision can be improved.