Modified 6x6 DFT Matrix for IEEE 802.11ac Pilot Tone Spectral Lines
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Solution Overview
Problem
Current communication systems, particularly those adhering to IEEE 802.11 standards, face challenges in avoiding spectral lines on pilots when using a six-by-six DFT matrix, which can lead to inefficiencies in signal transmission and reception.
Innovation Solution
The implementation of a modified six-by-six P matrix where one or more columns are multiplied by -1, avoiding a first row of all ones, thereby minimizing spectral lines and enhancing signal bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard six-by-six DFT matrix with first row of all ones is used, then the matrix structure is simple and easy to implement, but spectral lines are formed on pilot tones causing signal degradation
Solution Approach 1:
The patent modifies the DFT matrix by changing the sign parameter of selected elements in the first row from positive to negative. Specifically, for a 6x6 DFT matrix, elements at positions (0,1) and (0,3) are multiplied by -1, transforming the first row from [1,1,1,1,1,1] to [1,-1,1,-1,1,-1]. This parameter change eliminates spectral lines on pilot tones while maintaining the orthogonal structure and ease of implementation of the DFT matrix.
2Quantity of substance
If spectral lines are avoided by modifying the P matrix, then signal bandwidth utilization improves, but the matrix structure becomes more complex
Solution Approach 1:
The patent achieves spectral line avoidance through simple sign parameter changes rather than structural modifications. The modified P matrix maintains the same 6x6 dimensions and DFT structure, with only the signs of specific elements changed. This approach increases signal bandwidth utilization by eliminating spectral line interference while adding minimal complexity to the matrix structure.
Data Source
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AI summary
A communication device for generating a matrix-mapped sequence is described. The communication device includes sequence generation circuitry. The communication device also includes mapping circuitry coupled to the sequence generation circuitry. The mapping circuitry applies a first matrix with at least one column multiplied by -1 to a sequence. The communication device also includes a transmit block coupled to the mapping circuitry.