Multi-AP WLAN Synchronization Using Trigger Frames
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for multi-AP communication in WLANs, particularly in Infrastructure Basic Service Set (BSS) mode, lack effective synchronization and channel access schemes for peer-to-peer traffic between stations, leading to inefficiencies in signal decoding and transmission.
Innovation Solution
A method and apparatus for multi-AP communication involving a wireless transmit/receive unit (WTRU) that receives trigger frames from multiple access points (APs) to generate a synchronization frame, enabling synchronized data transmission from multiple APs based on these frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple APs transmit simultaneously without synchronization, then channel access efficiency improves, but signal decoding reliability deteriorates due to timing misalignment and interference
Solution Approach 1:
The system performs preliminary synchronization actions before simultaneous data transmission. The first AP transmits a trigger frame that initiates a predetermined time duration, during which the second AP synchronizes its transmission. This preliminary timing coordination ensures that both APs transmit data frames at precisely aligned times, resolving the contradiction by establishing reliable synchronization before enabling simultaneous channel access.
2Device complexity
If APs use independent channel access schemes, then device complexity is reduced, but transmission productivity deteriorates due to lack of coordination
Solution Approach 1:
The trigger frame acts as an intermediary mechanism that coordinates channel access between multiple APs without requiring complex inter-AP communication protocols. The first AP sends the trigger frame to initiate the predetermined time duration, and the second AP responds by synchronizing its transmission within this window. This intermediary approach enables coordinated simultaneous transmission while maintaining relatively simple device complexity.
3Loss of information
If trigger frames contain different information from different APs, then information completeness improves, but synchronization precision deteriorates
Solution Approach 1:
The trigger frame uses homogeneous information structure with identical predetermined time duration values from different APs. This homogeneity in the timing parameter allows receiving devices to precisely synchronize by referencing the same time value, while the trigger frame still conveys necessary transmission information. The predetermined time duration is set to a fixed value that ensures both APs align their data frame transmissions with high precision.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A method of multi-access point (multi-AP) communication performed by a wireless transmit/receive unit (WTRU) comprises: receiving (1510) a first trigger frame from a first access point (AP) of a plurality of APs, the first trigger frame comprising first information; receiving (1520) a second trigger frame from a second AP of the plurality of APs at a predetermined time duration after receiving the first trigger frame, the second trigger frame also comprising the first information of the first trigger frame; generating (1530) a synchronization frame based on the first trigger frame and the second trigger frame, the synchronization frame comprising synchronization information; transmitting the synchronization frame to at least the first AP and the second AP; and receiving (1540) a data transmission based on the synchronization information from each of the first AP and the second AP.