Virtual AP Subcarrier Assignment for DMIMO Synchronization
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Solution Overview
Problem
Wireless communications using Distributed Multiple-Input Multiple-Output (DMIMO) transmissions face synchronization difficulties due to residual Carrier Frequency Offset (CFO) build-up over time, leading to inefficient communication.
Innovation Solution
Assigning subcarriers of multiple access points to a subcarrier set of a virtual access point, generating a packet with a signal that encodes a preamble portion on assigned subcarriers and nulls unassigned subcarriers, and transmitting it to a station, allowing independent CFO estimation and correction using prediction algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMIMO transmissions use synchronization techniques to coordinate packet transmission from multiple APs, then packet transmission coordination is improved, but residual CFO build-up over time causes synchronization difficulties
Solution Approach 1:
The patent segments the subcarriers into different sets assigned to different APs within the virtual AP structure. By dividing the subcarrier space and assigning specific subcarriers to specific APs, the system enables independent CFO estimation for each AP while maintaining coordinated transmission. This segmentation prevents CFO accumulation from affecting the entire transmission, thereby resolving the synchronization accuracy versus time loss contradiction.
Solution Approach 2:
The patent implements feedback mechanisms where the STA estimates CFO for each AP independently based on the segmented subcarrier assignments. The STA provides feedback about the estimated CFO values, which are then used to correct the synchronization in subsequent transmissions. This feedback loop continuously compensates for residual CFO build-up, maintaining synchronization accuracy over time.
2Measurement precision
If subcarriers of multiple APs are assigned to a virtual AP subcarrier set, then independent CFO estimation is enabled, but signal overlap may occur between assigned subcarriers
Solution Approach 1:
The patent segments the subcarrier space by assigning specific subcarriers to specific APs within the virtual AP structure. By dividing the subcarrier space and assigning specific subcarriers to specific APs, the system enables independent CFO estimation for each AP while maintaining coordinated transmission. This segmentation prevents CFO accumulation from affecting the entire transmission, thereby resolving the synchronization accuracy versus time loss contradiction.
Solution Approach 2:
The patent applies local quality by assigning different subcarriers to different APs based on their specific requirements and roles. Each AP receives a dedicated subset of subcarriers, allowing for localized optimization of signal transmission and CFO estimation. This ensures that each AP's signal is transmitted on its designated subcarriers without interfering with other APs, eliminating signal overlap while maintaining measurement precision.
3Productivity
If preamble portion is encoded on assigned subcarriers and nulled on unassigned subcarriers, then DMIMO transmission efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the subcarrier space into assigned and unassigned portions for each AP. By systematically assigning specific subcarriers to specific APs and nulling the preamble on unassigned subcarriers, the system simplifies the packet generation process while maintaining transmission efficiency. The segmentation approach provides clear rules for which subcarriers should have preambles and which should be nullified, reducing the complexity of managing multiple AP transmissions.
Solution Approach 2:
The patent changes the parameter of subcarrier assignment dynamically based on the virtual AP configuration. By adjusting which subcarriers are assigned to which APs and accordingly adjusting the preamble encoding and nulling patterns, the system optimizes transmission efficiency without requiring complex manual configuration. The parameter changes are automated based on the virtual AP structure, reducing device complexity while improving productivity.
Data Source
AI summary
Embodiments of a method and an apparatus for wireless communications are disclosed. In an embodiment, a method for wireless communications involves assigning subcarriers of a first access point (AP) and a second AP to a subcarrier set of a virtual AP, generating, by the virtual AP, a packet that includes a signal for a station (STA) and that is transmitted using the subcarrier set, where generating the packet includes: encoding a preamble portion of the packet on the assigned subcarriers included in the subcarrier set, nulling the preamble portion of the packet for unassigned subcarriers of the first AP and the second AP, encoding a subsequent portion of the packet according to a Distributed Multiple-Input Multiple-Output (DMIMO) transmission, and transmitting the packet to the STA.