Differential PPDU Transmission with xIFS for Low Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless networking standards face challenges in achieving low latency transmission due to long TXOPs, which prevent real-time services like VR and AR from functioning efficiently, as other stations are not allowed to transmit during TXOPs, leading to performance degradation and increased latency.
Innovation Solution
Implementing differential PPDUs with a xIFS interval, allowing low latency stations to preempt transmissions during this interval, and dynamically expanding bandwidth by transmitting in additional subchannels, along with using PPDU end indication and padding to reduce latency further.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a station (STA) acquires a transmission opportunity (TXOP) and other STAs are not allowed to transmit during the TXOP, then transmission safety is guaranteed, but latency increases and low latency transmission is prevented
Solution Approach 1:
The patent segments the TXOP transmission into multiple shorter PPDUs transmitted at different times, creating gaps between transmissions. This allows other STAs to access the medium during these gaps for low latency traffic while the original STA maintains control of the TXOP, thus segmenting the monopoly to allow controlled sharing without compromising overall transmission safety
Solution Approach 2:
The patent introduces dynamic behavior by allowing the TXOP holder to selectively grant access to other STAs during specific intervals (xIFS) based on traffic needs. The system dynamically adjusts between exclusive transmission and shared transmission modes, enabling the TXOP duration and access rights to be flexible rather than fixed, thus reducing latency while maintaining reliability
2Productivity
If TXOPs last for a relatively long time to ensure complete transmission, then throughput is improved, but low latency transmission is prevented
Solution Approach 1:
The patent divides long TXOP transmissions into multiple shorter PPDUs transmitted at different time intervals. This segmentation maintains the overall long transmission window for high throughput while creating accessible gaps within the TXOP structure, allowing low latency STAs to transmit during these intervals without waiting for the entire TXOP to expire
Solution Approach 2:
The patent introduces an intermediary mechanism where the TXOP holder can indicate to other STAs when the medium becomes accessible during the TXOP. This intermediary signaling (through modified PPDUs with end indications) mediates between the need for long continuous transmission and the need to allow low latency access, coordinating multiple transmission goals without conflict
3Loss of time
If differential PPDUs are transmitted with xIFS interval to allow preemption, then low latency transmission is enabled, but device complexity increases
Solution Approach 1:
The patent makes existing PPDUs multi-functional by adding optional end indication fields that serve dual purposes: maintaining backward compatibility with legacy devices while enabling new low latency preemption functionality. The same PPDU structure serves both traditional long transmission and the new segmented preemption scheme, reducing the need for entirely new protocol elements
Solution Approach 2:
The patent changes the timing parameter from the standard SIFS to a new xIFS interval that incorporates both signal processing time and a preemption opportunity window. This parameter modification allows the system to maintain the familiar PPDU transmission framework while introducing controlled flexibility in timing that enables low latency access without requiring complete protocol redesign
Data Source
AI summary
Disclosed herein is a method performed by a wireless device in a wireless network to transmit differential physical layer protocol data units (PPDUs) to allow low latency transmission. The method includes wirelessly transmitting a plurality of PPDUs to a second wireless device using a x interframe space (xIFS) interval, wherein the xIFS interval comprises a signal processing interframe space (sIFS) interval that is used in the wireless network and a physical carrier sensing (Tpcs) interval during which other wireless devices are allowed to preempt transmission of the first wireless device.