LBT ECCA Backoff Counter for Unlicensed Band Frequency Reuse
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Solution Overview
Problem
The existing Listen Before Talk (LBT) scheme in LTE systems using unlicensed bands faces challenges in achieving a frequency reuse rate of 1 due to limitations in clear channel assessment (CCA) regulations, leading to inefficient channel occupancy and interference between base stations.
Innovation Solution
The proposed LBT scheme employs extended Clear Channel Assessment (ECCA) with random backoff counting, allowing transmitters to select a random number for backoff and decrement it upon channel idle detection, enabling simultaneous transmission and improving channel occupancy probability while aligning ECCA end timings among multiple transmitters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT regulations require CCA before transmission in unlicensed band, then interference between transmitters is reduced, but frequency reuse rate cannot achieve 1 and channel occupancy probability decreases
Solution Approach 1:
The patent applies dynamics by making the CCA procedure adaptable through variable backoff counters and dynamic freezing mechanisms. The backoff counter value is randomly selected and decremented dynamically based on channel conditions, allowing the system to adjust transmission timing adaptively rather than using fixed CCA intervals, thereby enabling frequency reuse rate of 1 while maintaining interference reduction
Solution Approach 2:
The patent changes parameters by introducing a configurable backoff counter parameter that can be randomly selected from a range of values. This parameter modification allows different transmitters to wait different durations before re-attempting CCA, creating temporal separation that reduces interference while allowing simultaneous frequency usage across different time slots
2Measurement precision
If base stations perform CCA independently in unlicensed band, then each station can detect channel clearness, but simultaneous transmission is limited and channel occupancy time is reduced
Solution Approach 1:
The patent applies preliminary action by having base stations perform CCA and select backoff counter values in advance before actual data transmission. The frozen backoff counter mechanism allows stations to prepare transmission timing beforehand and then wait for channel availability, enabling longer channel occupancy once the channel is acquired without requiring continuous CCA checks during the entire occupancy period
3Measurement precision
If CCA threshold is set to detect interference, then interference detection accuracy improves, but channel access probability decreases due to more frequent busy channel detection
Solution Approach 1:
The patent applies dynamics by implementing a frozen backoff counter mechanism that changes system behavior based on detected interference levels. When interference is detected during CCA, the backoff counter is frozen and not decremented, dynamically adjusting the waiting period based on real-time channel conditions. This allows accurate interference detection while managing channel access probability through adaptive backoff rather than simple rejection
Data Source
AI summary
The present invention relates to 5G or pre-5G communication system for supporting a higher data transmission rate after 4G communication system such as LTE. The present invention provides a method for transmitting data on the basis of a measurement of a channel of an unlicensed band in a mobile communication system, the method comprising the procedures of: selecting a random number for backoff counting; determining whether to decrement the random number by 1; decrementing the random number by 1 on the basis of the determining; determining whether the channel is idle by measuring the channel; completing the backoff counting if the random number becomes 0; and transmitting data by means of the channel if the backoff counting is completed.