Contention Window Size Adjustment for Wireless Interference
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Solution Overview
Problem
In wireless communication systems, especially in Licensed-Assisted Access (LAA), the existing methods for adjusting contention window size (CWS) are inadequate as they fail to accurately account for interference from hidden Wi-Fi nodes, leading to transmission collisions due to reliance on HARQ-ACK feedback that does not reflect remote unit-specific interference situations when multiple devices are scheduled for transmission.
Innovation Solution
A system and method that determines interference levels based on feedback information from each device, including HARQ-ACK and CQI, to adjust the contention window size dynamically, ensuring that if interference exceeds a predetermined level for a majority of devices, the CWS is increased, and if it's below a threshold for most devices, the CWS is decreased, thereby optimizing channel access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base unit increases the CWS to avoid collision with Wi-Fi transmission, then transmission collision is reduced, but channel access speed decreases
Solution Approach 1:
The patent segments the feedback mechanism by obtaining separate feedback information from each remote unit regarding their respective interference situations. This allows the base unit to make differentiated CWS adjustments for different remote units based on their individual interference experiences, rather than using a single collective feedback approach. This segmentation enables the system to achieve reliable collision avoidance for affected units while maintaining fast channel access for units without interference.
Solution Approach 2:
The patent applies local quality by allowing different contention window sizes to be configured for different remote units based on their specific interference conditions. Remote units experiencing hidden node interference from Wi-Fi can have larger CWS values assigned to them, while units without such interference can use smaller CWS values. This localized adjustment optimizes both collision avoidance for affected units and channel access speed for unaffected units.
2Productivity
If the base unit decreases the CWS for fast channel access, then channel access speed increases, but transmission collision with Wi-Fi increases
Solution Approach 1:
The patent implements dynamic CWS adjustment where the contention window size is not fixed but is adapted based on real-time feedback from remote units about their interference conditions. The base unit dynamically adjusts CWS values for different remote units based on their individual experiences with Wi-Fi interference, allowing the system to respond flexibly to changing channel conditions and optimize both access speed and collision avoidance.
Solution Approach 2:
The patent employs feedback mechanisms where remote units report their interference situations to the base unit. This feedback information is then used by the base unit to adjust the CWS values appropriately. The feedback loop enables the system to learn from actual transmission outcomes and continuously optimize the CWS settings to balance channel access speed with collision avoidance.
3Device complexity
If the CWS is adjusted based on collective HARQ-ACK feedback from all scheduled remote units, then the adjustment mechanism is simple, but it fails to reflect remote unit-specific interference situations
Solution Approach 1:
The patent segments the feedback collection process by obtaining separate feedback information from each remote unit individually, rather than relying on collective feedback from all scheduled units. This segmentation allows the base unit to detect and respond to unit-specific interference conditions, improving measurement precision while maintaining manageable complexity through systematic processing of individual feedback reports.
Data Source
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AI summary
Apparatuses, methods, and systems are disclosed for contention window size adjustment. One apparatus includes a transmitter that transmits data on a carrier to a set of devices in a first transmission burst having a duration of at least one subframe. In some embodiments, the set of devices includes one or more devices. In various embodiments, the apparatus includes a receiver that receives feedback information from each device. In certain embodiments, the apparatus includes a processor that determines, based on the feedback information, whether interference above a predetermined level exists on the carrier during the first transmission burst at each device, adjusts a contention window size based on the determination of whether interference above the predetermined level exists on the carrier during the first transmission burst at each device, and determines a value N between a predetermined minimum contention window size and the adjusted contention window size.