Unlicensed Band Signal Transmission via CCA Counter Reduction
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Solution Overview
Problem
LTE-A systems using unlicensed band frequencies face challenges in transmitting discovery signals at constant cycles due to restrictions on shared channels and interference from other LTE-A devices, leading to delayed access to channels during data transmission.
Innovation Solution
A method is introduced that reduces the counter value during clear channel assessment (CCA) for discovery signals and data transmission, storing the reduced counter value when only discovery signals are transmitted, and using it when data transmission resumes, allowing for prioritized transmission of discovery signals and data based on distinct LBT parameter sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clear channel assessment (CCA) is performed before data transmission on unlicensed band, then channel access reliability is improved, but transmission delay increases when discovery signals are transmitted during CCA period
Solution Approach 1:
The patent applies preliminary action by performing CCA check before data transmission to ensure channel availability. The counter is reduced during CCA period as a preparatory step, and if discovery signal transmission occurs, the stored counter value is used later to resume data transmission without full re-assessment, thus maintaining reliability while reducing delay.
Solution Approach 2:
The patent changes the counter parameter state by reducing it during CCA period and storing the reduced value. When discovery signal transmission interrupts data transmission, the stored counter value is restored and continued from, rather than resetting to initial value, effectively changing the parameter progression to avoid unnecessary delays.
2Reliability
If discovery signals are transmitted at constant cycles on unlicensed band, then discovery signal reliability is improved, but data transmission is delayed due to CCA counter reset
Solution Approach 1:
The patent applies discarding and recovering by temporarily discarding the counter reduction progress when discovery signal transmission takes precedence, storing the reduced counter value. When data transmission resumes, the stored counter value is recovered and continued from, preventing complete loss of channel access progress while ensuring discovery signal priority.
Solution Approach 2:
The patent introduces dynamic behavior to the counter management system. The counter reduction is dynamically adjusted based on transmission type: it continues during data transmission, pauses and stores progress during discovery signal transmission, and resumes from stored value when data transmission restarts, making the system adaptive to different transmission priorities.
3Adaptability or versatility
If unlicensed band is shared with other wireless transmitters, then spectrum utilization is improved, but transmission reliability deteriorates due to interference and usage restrictions
Solution Approach 1:
The patent applies feedback mechanism through CCA (Clear Channel Assessment) which continuously monitors the channel status before and during transmission attempts. The counter reduction and storage mechanism provides feedback-based adaptation: when channel is busy or discovery signal transmission occurs, the system adjusts by storing counter state and resuming later, thereby maintaining reliability in shared spectrum environment.
Solution Approach 2:
The patent uses preliminary CCA assessment action to check channel availability before data transmission on unlicensed band. This preliminary check allows the system to adapt to shared spectrum conditions by determining whether to proceed with transmission or wait, improving reliability despite spectrum sharing with other wireless transmitters.
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2
AI summary
Disclosed is a 5G or pre-5G communication system for supporting a data transmission rate higher than that of a 4G communication system such as LTE. Disclosed are: a method for transmitting a signal in an unlicensed band channel on the basis of a counter reduction in the unlicensed band channel of a mobile communication system and a clear channel assessment (CCA) of the channel; and a mobile communication system, and according to an embodiment of the present disclosure, the method for transmitting a signal in an unlicensed band channel on the basis of a counter reduction in the unlicensed band channel of a mobile communication system and a clear channel assessment (CCA) of the channel comprises the steps of: reducing the counter and performing a CCA for the channel, during a first period of transmitting a discovery signal and data; storing the reduced counter when a second period of transmitting only the discovery signal without the data is started; reducing the counter by using the stored counter and performing the CCA for the channel when a third period of transmitting the discovery signal and the data is started; and transmitting the discovery signal or the data on the channel on the basis of the counter value.