Wireless LAN Preemption Signaling for Low-Latency Traffic
Solution Overview
Problem
Existing wireless LAN technologies struggle to support efficient transmission of low latency (LL) traffic, particularly in scenarios requiring high throughput and reliability, especially when multiple links are involved.
Innovation Solution
A method and device for transmitting low latency (LL) traffic by including a preemption enable indication (PEI) in data frames, with preemption information indicating a preemption period within a transmit opportunity (TXOP) and supporting communication on multiple links, allowing for synchronized data transmission and reception across these links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If preemption operation is implemented for low latency traffic transmission, then transmission latency is reduced and communication efficiency is improved, but device complexity and protocol overhead increase
Solution Approach 1:
The AP includes preemption information in the response frame before the actual low latency traffic transmission begins. This preliminary action allows the STA to prepare for the preemption period by receiving advance notification of the preemption timing and parameters, thereby reducing the actual transmission latency without requiring complex real-time coordination protocols during the data transmission phase
Solution Approach 2:
The preemption information is conveyed through feedback in the response frame from the AP to the STA. This feedback mechanism provides the STA with essential preemption parameters (such as preemption start time, duration, and triggering conditions) in advance, enabling the STA to adjust its transmission schedule accordingly. The feedback approach simplifies the overall protocol by using standard frame structures rather than requiring complex new protocol mechanisms
2Productivity
If multiple links are supported for simultaneous communication, then throughput and system capacity are improved, but coordination complexity and interference management difficulty increase
Solution Approach 1:
The preemption operation is applied individually to each link within the multi-link system. Each link has its own preemption information and transmission parameters, allowing independent control and management of preemption on each link. This segmentation approach enables the system to support multiple links simultaneously without requiring complex global coordination, as each link operates autonomously with its own preemption timing and parameters
Solution Approach 2:
The preemption mechanism implements local quality control by applying different preemption parameters to different links based on their specific traffic conditions and requirements. Each link can have customized preemption timing, duration, and triggering conditions tailored to its local traffic patterns, thereby optimizing throughput for each link without requiring complex centralized coordination across all links
3Reliability
If channel access procedures are performed for each transmission, then transmission reliability is improved, but transmission time and efficiency deteriorate
Solution Approach 1:
The AP performs the channel access decision and preemption scheduling in advance by including preemption information in the response frame. This preliminary action eliminates the need for the STA to perform additional channel access procedures during the preemption period, as the access rights are already granted and scheduled. The STA can proceed directly to transmission within the preemption window, thereby maintaining reliability without the time overhead of repeated channel access checks
Solution Approach 2:
The preemption operation enables continuous useful action by allowing the STA to transmit data immediately within the preemption period without interruption for channel access procedures. The preemption information guarantees transmission rights for the specified duration, creating a continuous transmission window that eliminates idle waiting time and channel access overhead. This continuous action maximizes transmission efficiency while maintaining reliability through the AP's controlled preemption scheduling
Data Source
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AI summary
A method and device for a preemption operation in a wireless LAN are provided. A method of a station (STA) comprises transmitting a first data frame to an access point (AP), receiving a response frame including preemption information from the AP in response to the first data frame, and receiving low latency (LL) traffic from the AP based on the preemption information.