WiFi Multi-Link PPDU Transmission Alignment
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Solution Overview
Problem
In WiFi multi-link operations, PPDU ending time misalignment occurs due to differences in link capacity, leading to inefficient data transmission and synchronization issues across links with varying bandwidth, number of spatial streams, and modulation and coding mechanisms.
Innovation Solution
A method for aligning PPDU transmission by constraining or setting parameters of multiple links to ensure synchronized ending times, involving the transmission of PPDUs under uniform parameters or using higher capacity links to transmit additional PPDUs, ensuring that all links complete their transmissions within a predefined tolerance range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duplicate transmission is performed over high capacity link and low capacity link, then transmission reliability is improved, but PPDU ending time alignment deteriorates due to link capacity difference
Solution Approach 1:
The patent changes transmission parameters (bandwidth, MCS index, number of spatial streams) of PPDUs transmitted on different links to ensure that despite different link capacities, the PPDUs occupy the same time duration. This allows duplicate transmissions to maintain both reliability and timing alignment.
Solution Approach 2:
The system dynamically adjusts transmission parameters based on link capacity characteristics. For links with different capacities, the transmitter adapts parameters such as bandwidth and modulation scheme to equalize transmission duration, enabling flexible maintenance of PPDU alignment across varying link conditions.
2Ease of operation
If low capacity link's PPDU goes first and high capacity link's PPDU goes later, then transmission scheduling flexibility is improved, but PPDU ending time alignment deteriorates due to transmission timing difference
Solution Approach 1:
When PPDUs are transmitted at different times on different links, the patent adjusts transmission parameters of the later PPDU to ensure it occupies the same time duration as the earlier PPDU. This parameter adaptation maintains ending time alignment while preserving scheduling flexibility.
3Quantity of substance
If high capacity link transmits multiple PPDUs to fulfill data requirements, then data transmission completeness is improved, but PPDU ending time alignment deteriorates due to increased data loading
Solution Approach 1:
The patent segments data transmission into multiple PPDUs when needed on high capacity links. By dividing the data into appropriate segments and transmitting them as separate PPDUs with adjusted parameters, the system maintains timing alignment while ensuring complete data transmission.
Solution Approach 2:
The system dynamically changes transmission parameters including bandwidth, MCS index, and number of spatial streams based on the number of PPDUs being transmitted. This allows high capacity links to transmit multiple PPDUs while maintaining alignment with other links through parameter adaptation.
Data Source
AI summary
A physical protocol data unit (PPDU) transmission method includes aligning parameters of a plurality of links for constraining the plurality of links to have same capacity for PPDU transmission, and transmitting PPDUs via the plurality of links. Highest capacity supported by one of the plurality of links is different from highest capacity supported by another of the plurality of links. Each of the PPDUs is generated and transmitted under the same parameters. Ending time instants of transmission of the PPDUs are aligned.