Unlicensed Band Backoff Counter Adaptation for Channel Access
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Solution Overview
Problem
Wireless communication systems face challenges in efficiently transmitting and receiving data in unlicensed bands, particularly in adapting backoff operations to channel states and securing transmission opportunities, which affects data transmission efficiency and channel availability.
Innovation Solution
A method for performing backoff operations in wireless access systems supporting unlicensed bands, involving configuring a backoff counter, performing carrier sensing to check channel idle states, and transmitting reservation signals or data when the channel is idle, with the backoff counter value being maintained or decreased accordingly, and configuring transmission opportunity sections proportional to reservation signal lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backoff operation is performed in unlicensed bands, then channel availability is improved, but data transmission efficiency deteriorates due to waiting time
Solution Approach 1:
The patent applies dynamics by making the backoff counter decrement behavior adaptive rather than fixed. The backoff counter decreases only during backoff permitted durations when the channel is idle, rather than decrementing uniformly across all time periods. This dynamic adjustment allows the system to balance channel access reliability with transmission efficiency by being more aggressive in channel acquisition when conditions permit.
Solution Approach 2:
The patent changes the parameter of backoff counter decrement timing from a fixed schedule to a conditional schedule based on channel state. By modifying when the backoff counter decreases (only during idle periods in backoff permitted durations), the system optimizes both channel availability and transmission efficiency, resolving the contradiction between these two parameters.
2Adaptability or versatility
If carrier sensing operation is performed frequently to check channel idle state, then channel state adaptation is improved, but system complexity increases
Solution Approach 1:
The patent segments the time domain into backoff permitted durations and non-permitted durations, and further segments channel access into discrete backoff slots. Carrier sensing is performed only at these segmented time points rather than continuously, reducing system complexity while maintaining adequate channel state adaptation. This segmentation approach balances monitoring needs with operational simplicity.
3Reliability
If backoff counter value is maintained consistently in all subframes, then transmission opportunity securing is improved, but channel state responsiveness deteriorates
Solution Approach 1:
The patent implements dynamics by making the backoff counter maintenance behavior conditional on the subframe type. During backoff permitted durations, the counter is maintained to secure transmission opportunities. During non-permitted durations, the counter can be decreased to respond to channel state changes. This dynamic, conditional behavior resolves the contradiction between securing opportunities and maintaining responsiveness.
Data Source
AI summary
The present invention relates to a wireless connection system that supports unlicensed bands. A method for performing backoff, methods for configuring a reservation signal transmission and a transmission opportunity section, and apparatus supporting the same. A method for performing a backoff operation in a wireless connection system supporting unlicensed bands, that is an embodiment of the present invention, may comprises the steps of: configuring a backoff counter N so as to perform a backoff operation; determining whether a current sub-frame is a back-off permitted section; performing a carrier sensing (CS) operation for checking if an unlicensed band is in an idle state if the sub-frame is within a backoff permitted section, for each CS unit; decreasing the backoff counter N by 1 after performing the CS operation; and transmitting a reservation signal or data using a U cell that is formed in an unlicensed band if the backoff counter value expires. In this regard, the CS operation is not performed in sub-frames except for the backoff permitted section and the backoff counter value can be maintained continuously.