UL OFDMA Random Access via OBO Decrement in WLAN
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Solution Overview
Problem
Current WLAN systems face inefficiencies in random access methods, leading to increased power consumption and collision probabilities during data transmission, particularly in allocating and managing random access resources.
Innovation Solution
A method for uplink Orthogonal Frequency Division Multiple Access (UL OFDMA) random access in WLAN systems, where a Station (STA) sets a random OFDMA Back-Off (OBO) value within a Contention Window, decrements it based on received Trigger Frames, and transmits a random access request when the value reaches zero, using resources allocated by the frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a STA continuously monitors for random access opportunities, then the probability of successful access increases, but power consumption increases
Solution Approach 1:
The patent implements periodic monitoring by defining specific beacon intervals during which STAs wake up to check for Trigger Frames containing random access opportunities. Instead of continuous monitoring, STAs periodically activate at predetermined intervals synchronized with the AP's beacon transmission, thereby reducing power consumption while maintaining access probability through structured periodic opportunities.
Solution Approach 2:
The patent uses preliminary action by having the AP pre-announce the number of Trigger Frames and random access resource units in advance within beacon frames. STAs can determine beforehand whether to wake up and monitor based on this preliminary information, avoiding unnecessary power consumption when no access opportunities are available while still capturing opportunities when they are announced.
2Speed
If multiple STAs transmit random access requests simultaneously, then access speed increases, but collision probability increases
Solution Approach 1:
The patent segments the random access process into multiple distinct phases: first, STAs monitor beacon frames for announcements of Trigger Frame opportunities; second, STAs wake up at predetermined intervals to check for these opportunities; third, STAs transmit requests only when opportunities are detected. This segmentation temporalizes the access process, allowing multiple STAs to operate at different times rather than simultaneously, thereby maintaining speed through parallel opportunity structures while reducing collisions through temporal separation.
Solution Approach 2:
The patent implements dynamics by making the monitoring and transmission behavior adaptive based on announced opportunities. STAs dynamically adjust their activity patterns - waking up only when Trigger Frames are announced and remaining in sleep mode otherwise. This dynamic behavior allows the system to accommodate multiple STAs efficiently by activating them only when resources are available, preventing simultaneous collisions while maintaining rapid access when opportunities arise.
3Reliability
If the Contention Window size is increased to reduce collisions, then collision probability decreases, but access delay increases
Solution Approach 1:
The patent introduces a new temporal dimension by implementing periodic beacon intervals with predetermined wake-up opportunities. Instead of relying solely on adjusting the Contention Window size within a single access dimension, the system creates multiple access opportunities across different time intervals. This dimensional shift allows the system to maintain smaller Contention Windows (reducing delay) while providing multiple staggered opportunities (maintaining low collision probability through temporal distribution rather than spatial expansion).
Data Source
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AI summary
A method for performing uplink Orthogonal Frequency Division Multiple Access (UL OFDMA) based random access to an Access Point (AP) by a Station (STA) in a Wireless Local Area Network (WLAN) system is proposed. For the purpose, the STA sets a random value within an OFDMA Contention Window (CWO) as an OFDMA Back-Off (OBO) value, receives a beacon frame from the AP, the beacon frame including transmission start time information of one or more Trigger Frames for Random Access (TF-Rs), decrements the OBO value based on reception of the one or more TF-Rs, and if the OBO value reaches 0, transmits a random access request frame in resources selected randomly from among resources allocated to the STA.