Beamforming NDP LTF Matrix Design
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Solution Overview
Problem
Existing beamforming techniques in wireless networks, particularly those adhering to the IEEE 802.11 standard, are limited by the absence of a status bit to indicate when the number of long training fields (LTFs) in a null data packet (NDP) exceeds the number of antennas, hindering performance improvement.
Innovation Solution
A beamformer system that generates and transmits a null data packet (NDP) with a number of LTFs greater than the number of antennas, using a spatial mapping matrix product of two orthogonal matrices, eliminating the need for a status bit by leveraging the LTFs and spatial time streams within the IEEE 802.11 standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of LTFs in the NDP is increased to improve beamforming performance and signal-to-noise ratio, then the beamforming performance improves, but the IEEE 802.11 standard compliance is violated due to absence of status bit
Solution Approach 1:
The patent extracts the essential function of indicating LTF count from the status bit mechanism and implements it through alternative means (matrix dimension relationships) that do not require the status bit, thus maintaining standard compliance while achieving improved beamforming performance
Solution Approach 2:
The patent changes the parameter relationship by making the number of LTFs greater than the number of antennas, and uses the spatial mapping matrix dimensions (rows equal to antenna count, columns equal to LTF count) to encode this relationship without requiring explicit status indication
2Measurement precision
If the number of LTFs is made greater than the number of antennas to improve signal-to-noise ratio, then the signal-to-noise ratio improves, but the device complexity increases due to additional matrix operations
Solution Approach 1:
The patent introduces dynamic matrix operations where the spatial mapping matrix dimensions adapt to the relationship between LTF count and antenna count, allowing flexible configuration without fixed structural constraints
Solution Approach 2:
The patent adds a dimensional relationship between matrix rows (antennas) and columns (LTFs) to encode the configuration information, using the matrix structure itself rather than additional signaling bits to convey the LTF-to-antenna ratio
Data Source
AI summary
A beamformer generates a null data packet (NDP) that includes various long training fields (LTFs). The beamformer generates the NDP based on a spatial mapping matrix that is a product of two matrices. One matrix has a number of rows equal to a number of antennas of the beamformer, and a number of columns equal to a number of LTFs in the NDP. Further, the other matrix has a number of rows and a number of columns equal to the number of LTFs in the NDP. The number of LTFs in the NDP is greater than a number of antennas of the beamformer. Further, the beamformer transmits the NDP to a beamformee to obtain channel state information associated with a channel between the beamformer and the beamformee, and enable beamforming therebetween.