Transmitter Latency Control via Clear Channel Assessment Timing
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Solution Overview
Problem
Existing wireless communication systems under clear channel assessment (CCA) requirements face challenges in controlling latency variation (jitter) and ensuring predictable packet transmission times, which is crucial for applications like time-sensitive networking (TSN) where low latency and no jitter are essential.
Innovation Solution
A method and apparatus for determining a maximum required time for clear channel assessment and enforcing a specific duration to elapse after each packet transmission, ensuring that subsequent packets are transmitted only after this time has passed, thereby controlling latency variation and enabling predictable packet transmission times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clear channel assessment procedure is used for packet transmission, then channel access reliability is improved, but latency variation increases
Solution Approach 1:
The patent determines the maximum required time for clear channel assessment in advance, before actual packet transmission occurs. This preliminary determination of the time parameter allows the system to pre-calculate and pre-announce the transmission timing, enabling receivers to wake up only at predictable intervals while ensuring the CCA procedure will complete within the specified time window.
Solution Approach 2:
The patent dynamically adjusts the packet transmission schedule based on the determined maximum CCA time. By making the transmission timing adaptive to the actual CCA duration requirements, the system maintains reliable channel access while minimizing latency variation, as transmissions are scheduled exactly when needed rather than using fixed periodic intervals.
2Reliability
If clear channel assessment procedure is used for packet transmission, then channel access reliability is improved, but predictable transmission timing deteriorates
Solution Approach 1:
The patent determines and announces the maximum CCA time in advance, before actual transmission occurs. This preliminary action creates a predictable timeline that both transmitter and receiver can rely on, ensuring that while the CCA procedure itself may vary in duration, the overall transmission timing remains predictable and precise.
3Loss of time
If maximum required time for clear channel assessment is determined and enforced, then latency variation is reduced, but transmission productivity decreases
Solution Approach 1:
The patent changes the time parameter by determining the maximum required CCA time and using this as the basis for scheduling subsequent transmissions. Rather than using fixed periodic intervals or waiting for variable CCA completion, the system schedules transmissions based on this determined maximum time parameter, achieving predictable latency while maintaining efficient channel utilization.
Data Source
AI summary
Disclosed is a latency control method of a transmitter apparatus adapted for transmission of a plurality of packets under clear channel assessment requirements and latency requirements. The method comprises determining a maximum required time for clear channel assessment for the plurality of packets and determining a duration of time related to the determined maximum required time. For example, the duration of time may be determined as being equal to the determined maximum required time for clear channel assessment plus an offset. The offset may be equal to zero, or may be equal to a positive value. In some embodiments, the offset may be equal to, or larger than, a duration of another packet (which is not comprised in the plurality of packets). The method also comprises enforcing, for each packet of the plurality of packets, the determined duration of time to elapse after completion of transmission of the packet, before transmission of a subsequent packet of the plurality of packets is initiated. Corresponding latency control apparatus, transmitter apparatus, communication device and computer program product are also disclosed.