WLAN Trigger Frame Structure for Mixed HE and EHT Uplink PPDUs
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Solution Overview
Problem
Existing IEEE 802.11be EHT wireless local area networks face challenges in efficiently triggering different types of physical layer protocol data unit (PPDU) transmissions due to the presence of HE and R1/R2 EHT stations, as R1 EHT stations do not support frequency domain aggregated PPDUs, necessitating an enhanced trigger frame to manage diverse PPDU types.
Innovation Solution
An enhanced trigger frame is introduced with a first subfield to differentiate between 802.11ax and enhanced trigger frames, and a second subfield to specify the type of PPDU transmissions, allowing for HE and EHT TB PPDU transmissions, including a third type for TB FD-A-PPDU with orthogonal HE and EHT LTF symbols, and specific bandwidth and resource unit allocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single type of trigger frame is used for all PPDU transmissions, then the frame structure is simple, but it cannot support diverse PPDU transmission types (HE TB, EHT TB, TB FD-A) from different station types
Solution Approach 1:
The trigger frame is segmented into multiple subfields within the Common Information Field (CIF), including a First Subfield for frame type indication, a Second Subfield for PPDU type indication, and a Third Subfield for LTF symbol indication. This segmentation allows each subfield to independently specify different transmission parameters, enabling support for multiple PPDU types while maintaining a structured and manageable frame format.
Solution Approach 2:
The enhanced trigger frame is designed with multi-functionality to serve multiple purposes: it can trigger HE TB PPDU transmissions from HE STAs, EHT TB PPDU transmissions from EHT STAs, and TB FD-A PPDU transmissions from both HE and EHT STAs. The universal frame structure uses bit fields that can be interpreted differently based on the indicated PPDU type, allowing a single frame format to handle diverse transmission scenarios.
2Productivity
If frequency domain aggregated PPDU transmission is used for large bandwidth, then throughput is maximized, but R1 EHT STAs cannot support this transmission type
Solution Approach 1:
The trigger frame incorporates dynamic indication fields that allow the AP to selectively trigger different PPDU transmission types based on the capabilities of associated STAs. The frame type indication subfield and PPDU type indication subfield enable dynamic adaptation of the transmission mode, allowing the system to use frequency domain aggregation when beneficial while falling back to compatible transmission modes when necessary, thus optimizing throughput across heterogeneous STA populations.
Solution Approach 2:
The trigger frame uses parameter changes in the form of bit field values to indicate different transmission modes. By changing the values in the frame type indication subfield and PPDU type indication subfield, the system can switch between supporting frequency domain aggregated transmissions for high throughput and traditional transmissions for compatibility, thereby adapting to different STA capabilities without changing the fundamental frame structure.
3Adaptability or versatility
If multiple trigger frame types are implemented to support different PPDU transmissions, then all station types can be supported, but the frame processing complexity increases
Solution Approach 1:
The trigger frame performs preliminary action by pre-indicating the PPDU type and frame type in the Common Information Field before the actual transmission occurs. The PPDU type indication subfield and frame type indication subfield are set in advance, allowing receiving STAs to prepare their processing logic ahead of time based on the indicated transmission mode. This preliminary configuration simplifies the actual reception and processing phases by eliminating the need for complex real-time frame type detection.
Data Source
AI summary
A method for triggering uplink transmission comprises generating, by an access point (AP), a trigger frame based on a type of physical layer protocol data unit (PPDU) transmissions to be solicited from a plurality of stations (STAs) in the WLAN, wherein a common information field of the trigger frame indicating whether or not a special user information field is present in the trigger frame; and transmitting the trigger frame to the plurality of STAs.