Preemption Indication for Low Latency Channel Access
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Solution Overview
Problem
In wireless local area networks (WLANs), devices with low latency traffic often face delays as they must wait until the end of a transmission opportunity (TXOP) to transmit, leading to increased latency in critical applications.
Innovation Solution
The method involves transmitting a preemption indication during the interframe space between the end of a first physical layer protocol data unit (PPDU) and the scheduled start time of a second PPDU, allowing a third PPDU to preempt the second PPDU within the TXOP, thereby reducing latency for low latency data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If devices wait until the end of a TXOP to transmit low latency traffic, then the scheduled PPDU transmission is maintained, but the latency of low latency data increases
Solution Approach 1:
The system transmits a preemption indication during the interframe space before the scheduled PPDU transmission begins, allowing the transmitting device to prepare and send low latency traffic immediately without waiting for the TXOP to end. This preliminary signaling enables the scheduled transmission to be interrupted and replaced by higher priority traffic.
Solution Approach 2:
The patent introduces dynamic preemption capability that allows the TXOP structure to be modified in real-time based on traffic priority requirements. The preemption indication mechanism enables flexible reconfiguration of the transmission schedule, allowing low latency traffic to preempt scheduled PPDUs while maintaining the overall TXOP framework for normal traffic.
2Loss of time
If a preemption indication is transmitted during interframe space, then low latency data can be transmitted earlier, but the complexity of channel access protocols increases
Solution Approach 1:
The preemption indication serves as an intermediary signal transmitted during the interframe space that mediates between the scheduled PPDU transmission and the need for low latency traffic. This intermediate signaling mechanism allows the system to coordinate preemption without requiring complex real-time negotiation or reconfiguration protocols, as the indication itself carries the necessary authorization information.
3Device complexity
If one PPDU is transmitted per TXOP, then the transmission structure is simplified, but devices with low latency traffic must wait until the end of the TXOP causing increased latency
Solution Approach 1:
The patent segments the TXOP into multiple transmission opportunities by allowing preemption indications to divide the original single PPDU transmission into multiple smaller transmissions. The first PPDU carries the preemption indication, and subsequent PPDUs carry the low latency traffic, effectively segmenting the transmission timeline to accommodate priority traffic without abandoning the overall TXOP structure.
Data Source
AI summary
This disclosure provides methods, components, devices and systems for low latency channel access. Some aspects more specifically relate to preemption of existing transmission opportunities (TXOPs) such that devices with low latency traffic to transmit may access the communication medium to transmit low latency traffic. Short physical layer protocol data units (PPDUs) may be used within TXOPs with interframe spaces between the PPDUs such that a device with low latency traffic may transmit a preemption indication during the interframe space. A first wireless communication device may identify low latency traffic during a first PPDU of a TXOP assigned to a second wireless communication device. The first wireless communication device may transmit a preemption indication in an interframe space that indicates that a subsequent scheduled PPDU in the TXOP will be preempted in order for the first wireless communication device to transmit a PPDU to convey the low latency traffic.