C-OFDMA Preamble Puncturing for Multi-AP Interference
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Solution Overview
Problem
Current wireless LAN systems face challenges in efficiently utilizing increased spatial streams and managing interference in multi-AP environments, particularly in transmitting Coordinated-Orthogonal Frequency Division Multiple Access (C-OFDMA) PPDU, which affects resource allocation and interference avoidance.
Innovation Solution
A method and apparatus for transmitting C-OFDMA PPDU using a preamble puncturing technique, where a first AP transmits a C-OFDMA request frame to a second AP, allowing the second AP to use a busy channel by puncturing the preamble, thereby enabling simultaneous transmission and optimizing resource usage across multiple access points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple APs transmit simultaneously on the same channel, then resource utilization and throughput are improved, but interference between BSS increases
Solution Approach 1:
The channel is segmented into control portion and data portion. The control portion (preamble) is punctured to avoid interference, while the data portion can be transmitted simultaneously by multiple APs. This segmentation allows selective application of puncturing technique only where necessary.
Solution Approach 2:
Preamble puncturing is applied locally only to the control portion of the signal, while the data portion maintains full transmission. This localized application of puncturing minimizes interference impact while preserving throughput potential.
2Reliability
If a single AP transmits on a busy channel, then interference avoidance is improved, but resource utilization deteriorates
Solution Approach 1:
The system dynamically adjusts transmission strategy based on channel conditions. When the channel is busy, multiple APs can simultaneously transmit with preamble puncturing enabled, allowing the system to adapt to varying channel states and optimize both interference avoidance and resource utilization.
Solution Approach 2:
Preamble puncturing acts as an intermediary mechanism that enables simultaneous transmission by multiple APs on busy channels. By selectively removing the preamble in certain subchannels, it mediates between the need for interference avoidance and the desire for resource utilization.
3Productivity
If increased spatial streams are used, then throughput is improved, but signaling complexity increases
Solution Approach 1:
Instead of applying puncturing to all subchannels, the technique applies it only to specific subchannels where interference occurs. This partial application reduces signaling overhead while maintaining the throughput benefits of multiple spatial streams.
Data Source
AI summary
Proposed is a method and apparatus for transmitting a C-OFDMA PPDU in a wireless LAN system. Specifically, a first AP transmits a C-OFDMA request frame to a second AP. The first AP receives a C-OFDMA response frame as a response to the COFDMA request frame from the second AP. The first AP transmits a first C-OFDMA PPDU to a first STA through a first channel. A second C-OFDMA PPDU is transmitted simultaneously together with the first PPDU through a second channel by the second AP. The C-OFDMA request frame includes first information indicating that using the second channel for the second AP is allowed. The first channel corresponds to a channel remaining after excluding a preamble-punctured channel from the entire channel, and the second channel corresponds to the preamble-punctured channel.