PPDU End Time Alignment in NSTR Wireless Modules
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Solution Overview
Problem
In wireless communication systems operating in the non-simultaneous transmit and receive (NSTR) mode, achieving accurate end time alignment of physical layer protocol data units (PPDUs) across multiple links is challenging due to hardware limitations and semiconductor process variations, leading to potential interference.
Innovation Solution
A reference point based PPDU end time alignment mechanism is employed, where timestamps of reference points on both links are obtained, and the length of the second PPDU is calculated to align its end with the first PPDU, ensuring precise alignment by using fixed idle times and known transmission times, thus avoiding parameters affected by semiconductor processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the PPDU transmitted later calculates the remaining length in real time based on chip parameters such as clock frequency or semiconductor process variation, then the PPDU length can be dynamically adjusted, but the alignment precision deteriorates because the calculated length becomes variable or incorrect
Solution Approach 1:
The patent applies preliminary action by pre-calculating the PPDU length at the MAC layer before transmission, rather than calculating it in real-time at the PHY layer during transmission. This pre-calculation is based on known parameters such as the first PPDU's transmission time and the second link's readiness time, allowing the second PPDU's length to be determined in advance with high precision, thus avoiding the alignment precision deterioration caused by real-time calculation uncertainties
Solution Approach 2:
The patent introduces an intermediary mechanism by using the MAC layer as a mediator between the two links. The MAC layer calculates the required PPDU length based on timestamps and timing information from both links, then provides this pre-calculated length to the PHY layer for transmission. This intermediary calculation approach resolves the contradiction by decoupling the dynamic length adjustment from the precision-critical real-time transmission process
2Productivity
If multiple PPDUs are transmitted simultaneously via two links, then communication efficiency is improved, but interference between links occurs due to misaligned end times
Solution Approach 1:
The patent applies feedback by using timestamp information from both links to monitor and adjust the PPDU transmission timing. The system obtains timestamps indicating when each link is ready to transmit, compares these timing information, and adjusts the second PPDU's length accordingly to ensure both PPDUs end at the same time. This feedback mechanism enables simultaneous transmission without interference by continuously monitoring and adjusting transmission parameters
Solution Approach 2:
The patent implements dynamics by making the second PPDU's length dynamic and adaptive based on the actual timing conditions of both links. Rather than using fixed lengths or real-time calculations during transmission, the system dynamically determines the optimal length in advance based on the second link's readiness time relative to the first link's transmission schedule, enabling flexible simultaneous transmission while maintaining precise end-time alignment
Data Source
AI summary
The present invention provides a control method of a wireless communication module having a first link and a second link. The control method includes the steps of: obtaining a first timestamp of a first reference point corresponding to a first PPDU, wherein the first PPDU is transmitted on a channel corresponding to the first link; obtaining a second timestamp of a second reference point corresponding to the second link, wherein the second reference point is a slot boundary, a transmission end or a reception end; determining a length of a second PPDU according to the first timestamp and the second timestamp, to make an end of the second PPDU is aligned to an end of the first PPDU; and generating the second PPDU according to the determined length of the second PPDU, and transmitting the second PPDU after the second reference point.