PPDU Preamble Shortening for TXOP Preemption in Wi‑Fi
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Solution Overview
Problem
Existing wireless communication systems, such as IEEE 802.11ax-2021, limit traffic throughput and inefficiently utilize channel resources due to the AP allocating time resources to only one STA, failing to consider available frequency resources in TXOP sharing.
Innovation Solution
Introduce a new PPDU format for preemption operation, allowing APs and STAs to transmit frames with varying preamble durations and enabling preemption requests for low-latency traffic, thereby optimizing channel utilization and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the AP allocates time resources to only one STA in TXOP sharing, then the system maintains simple time allocation management, but the traffic throughput is limited and channel utilization is inefficient
Solution Approach 1:
The patent segments the TXOP into multiple time segments and allocates them to different STAs. Instead of allocating the entire TXOP to a single STA, the AP divides the transmission opportunity into multiple time segments, each assignable to different STAs, thereby increasing overall throughput while maintaining manageable complexity through structured time division.
Solution Approach 2:
The patent introduces frequency resource consideration into the TXOP sharing mechanism. By combining time segmentation with frequency resource allocation, the system moves from one-dimensional time allocation to two-dimensional time-frequency resource management, enabling multiple STAs to utilize different frequency resources simultaneously within the same TXOP.
2Productivity
If the AP uses a full preamble for all frames, then legacy STAs can properly decode the frames, but the transmission efficiency is reduced due to unnecessary overhead
Solution Approach 1:
The patent segments the preamble into essential signaling fields and optional legacy compatibility fields. The critical information is conveyed through compact signaling elements, while legacy STA compatibility is maintained through selective inclusion of necessary legacy fields, reducing overall overhead while preserving interoperability.
Solution Approach 2:
The patent applies different preamble structures to different frames or transmission scenarios. Instead of using a uniform full preamble for all transmissions, the system selectively applies legacy compatibility fields only where necessary, optimizing each transmission's preamble structure based on the specific requirements of that frame and the intended recipients.
3Loss of time
If the AP transmits frames with longer intervals to allow preemption, then low-latency traffic can be accommodated, but the channel utilization efficiency decreases
Solution Approach 1:
The patent implements dynamic frame interval adjustment based on preemption requests. Instead of using fixed intervals, the system adaptively modifies the time gaps between frames in response to preemption requests, allowing shorter intervals when preemption is not needed (maintaining channel efficiency) and longer intervals when preemption is required (reducing latency).
Solution Approach 2:
The patent maintains continuous channel utilization by allowing preemption operations to occur within the existing TXOP structure. Rather than creating idle gaps in the transmission schedule, the system enables low-latency traffic to preempt ongoing transmissions, ensuring the channel remains actively used while accommodating urgent traffic needs.
Data Source
AI summary
An access point (AP) for facilitating communication in a wireless network. The AP includes a memory and a processor. The AP obtains a transmission opportunity (TXOP) on a wireless channel. The AP transmits, to a station (STA), a plurality of frames including a first frame and a second frame. The second frame is transmitted after the first frame. The first frame includes a first preamble and the second frame includes a second preamble, the second preamble having a shorter duration than the first preamble.