Dynamic Backoff Exponent Adjustment for Wireless Channel Access
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Solution Overview
Problem
The existing CSMA/CA algorithm in wireless sensor networks experiences increased data transmission delays due to large backoff periods and varying backoff times, leading to slow data access and potential contention data stranded in later contention access periods.
Innovation Solution
A channel access method that randomly selects a backoff period based on a backoff exponent, with the option to use a middle backoff when the selected period is large, and updates the backoff exponent based on channel access results to optimize channel access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a binary exponential backoff algorithm with macMinBE=3 is used, then collision avoidance is improved, but data transmission delay increases
Solution Approach 1:
The patent dynamically adjusts the backoff exponent BE based on the current contention window size CW and a threshold parameter. When CW is small (low contention), a smaller BE is used to reduce backoff time. When CW is large (high contention), a larger BE is used to reduce collisions. This dynamic adjustment resolves the contradiction by adapting the backoff behavior to actual channel conditions rather than using a fixed macMinBE=3.
Solution Approach 2:
The patent changes the backoff exponent parameter from a fixed value (macMinBE=3) to a variable value that can range from 1 to 5, selected based on current network conditions. Specifically, when CW ≤ threshold, BE is set to 1 or 2; when CW > threshold, BE is set to 3, 4, or 5. This parameter change allows the system to optimize between collision avoidance and transmission delay based on actual contention levels.
2Reliability
If optional backoff time doubles each time with macMinBE=3, then collision probability is reduced, but data access speed decreases
Solution Approach 1:
The patent makes the backoff time selection dynamic by introducing a threshold-based mechanism. When the contention window CW is small (indicating low collision risk), the system selects smaller backoff values (corresponding to BE=1 or 2), enabling faster data access. When CW is large (indicating high collision risk), larger backoff values are selected (BE=3, 4, or 5) to reduce collision probability. This dynamic behavior resolves the contradiction between collision avoidance and access speed.
Solution Approach 2:
The patent changes the backoff exponent parameter dynamically based on the relationship between CW and a threshold. The parameter selection logic is: if CW ≤ threshold, then BE ∈ {1, 2}; if CW > threshold, then BE ∈ 3, 4, or 5. This parameter change strategy allows the system to adaptively balance between minimizing collision probability and maximizing data access speed based on current network conditions.
3Reliability
If a large backoff period is selected, then channel access collision is avoided, but data transmission delay increases
Solution Approach 1:
The patent introduces dynamic adjustment of the backoff exponent based on the contention window size. When CW is small, indicating low contention and low collision risk, the system uses smaller BE values (1 or 2) resulting in shorter backoff periods and reduced delay. When CW is large, indicating high contention and high collision risk, the system uses larger BE values (3, 4, or 5) resulting in longer backoff periods and better collision avoidance. This dynamic behavior resolves the contradiction.
Solution Approach 2:
The patent changes the backoff exponent parameter from a fixed value to a variable that can be 1, 2, 3, 4, or 5, selected based on whether CW is greater than or less than or equal to a threshold. This parameter change enables the system to select appropriate backoff periods dynamically: shorter periods when collision risk is low, and longer periods when collision risk is high, thereby resolving the contradiction between collision avoidance and delay.
Data Source
AI summary
A channel access method and a node are disclosed. The method includes randomly selecting a backoff period XB according to a backoff exponent BE, where XB=X×aUnitBackoffPeriod, and X is an integer randomly selected from 0−(2BE−1); when X is greater than or equal to a predetermined value, determining a middle backoff, where the middle backoff is less than the backoff period, performing a backoff until the middle backoff ends and then performing a CCA; if a channel is clear, performing data transmission, and if the channel is not clear, continuing the backoff until the backoff period ends and then performing a CCA, and executing a channel access operation according to a result of the CCA performed when the backoff period ends. Therefore, data transmission is performed when a channel is clear, which can reduce a data transmission delay.