LBT Configuration for Unlicensed Band Coexistence
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Solution Overview
Problem
In cellular networks operating on unlicensed radio bands, there is a challenge in efficiently transmitting Sounding Reference Signals (SRS) and other signals without causing interference or data transmission collisions, particularly due to the lack of effective channel sensing and Listen Before Talk (LBT) mechanisms that can ensure fair coexistence with other systems.
Innovation Solution
Determining channel sensing metrics such as channel occupancy and link quality metrics to select appropriate LBT modes and sensing times, allowing User Equipment (UE) to perform LBT operations and transmit signals only when the channel is unoccupied, thereby reducing interference and collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT mechanisms are implemented to reduce interference and collisions, then coexistence fairness is improved, but device complexity and operational overhead increase
Solution Approach 1:
The patent implements LBT mechanisms by changing the operational parameters of the cellular network, specifically introducing channel sensing metrics, LBT modes, and sensing time configurations. These parameter changes enable the system to detect channel occupancy and adjust transmission behavior accordingly, improving coexistence fairness with other unlicensed band users while managing the added complexity through standardized parameter sets
Solution Approach 2:
The patent applies preliminary action by performing channel sensing and LBT procedures before actual data transmission. The system determines channel occupancy and selects appropriate LBT modes in advance, ensuring that transmissions only occur when the channel is clear. This preliminary detection and decision-making process prevents collisions and interference before they occur
2Reliability
If channel sensing metrics are determined and LBT operations are performed, then interference and collisions are reduced, but transmission time and operational overhead increase
Solution Approach 1:
The patent implements partial action by performing channel sensing for specific signal types selectively. Not all signals require full LBT procedures - the system determines appropriate LBT modes based on signal characteristics, channel conditions, and QoS requirements. This selective application of LBT reduces unnecessary sensing time while maintaining interference reduction benefits where needed
Solution Approach 2:
The patent applies dynamics by making LBT sensing time and mode flexible rather than fixed. The system dynamically adjusts sensing duration and LBT mode selection based on real-time channel occupancy metrics, signal type, and traffic conditions. This dynamic adaptation allows the system to minimize transmission time when conditions permit while ensuring reliable interference avoidance when necessary
Data Source
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AI summary
Apparatus, systems, and methods provide for transmitting a Sounding Reference Signal (SRS) or other reference signal over a cellular network operating on an unlicensed radio band. Specifically, an apparatus, such as a User Equipment (UE) or Base Station (eNB), determines one or more channel sensing metrics for a radio channel. Based on the channel sensing metrics, the apparatus then determines a Listen Before Talk (LBT) mode and/or a LBT sensing time. The UE then performs a LBT process using the LBT mode and the LBT sensing time. If the UE determines that the radio channel is not occupied, the UE transmits a signal, such as a control signal (e.g., a Sounding Reference Signal (SRS)), over the radio channel.