Transmit-Sensing Beam Mapping for Directional LBT Access
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Solution Overview
Problem
Existing wireless communication systems operating on unlicensed spectrum lack efficient methods for associating transmit and sensing beams for channel access, particularly in high-frequency ranges like FR2, leading to suboptimal channel access and potential transmission failures.
Innovation Solution
Implementing explicit mapping configurations between transmit and sensing beams using TCI states and mapping tables to facilitate both omni-directional and directional LBT, allowing for flexible beam selection and COT sharing, thereby enhancing channel access opportunities and reducing transmission failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directional LBT is used with beam-based transmission in unlicensed spectrum, then transmission reliability is improved through targeted channel access, but device complexity increases due to beam mapping and multiple LBT procedure requirements
Solution Approach 1:
The network configures beam mapping relationships between transmit beams and sensing beams in advance through RRC signaling or MAC CE. This preliminary configuration establishes the association between uplink transmit beams and downlink sensing beams before actual transmission, enabling the UE to perform directional LBT efficiently without real-time complex calculations
Solution Approach 2:
The patent introduces sensing beams as an intermediary element between the UE's transmit beams and the unlicensed channel. The sensing beams are used to perform LBT procedures on behalf of the transmit beams, decoupling the complexity of directional channel access from the actual data transmission process
2Productivity
If multiple sensing beams are configured for a single transmit beam, then channel access opportunities increase through multiple LBT attempts, but processing time increases due to sequential LBT procedures
Solution Approach 1:
When multiple sensing beams are configured for a single transmit beam, the UE performs LBT procedures periodically across these beams in a predetermined sequence. The network configures the beam switching periodicity and LBT timing relationships, allowing the UE to attempt channel access on multiple beams systematically without excessive delays
Solution Approach 2:
The network provides advance configuration of beam mapping relationships and LBT timing parameters through RRC signaling or MAC CE. This preliminary setup includes indicating which sensing beams are associated with which transmit beams, and configuring the temporal relationships between LBT attempts on different beams, enabling efficient multi-beam LBT without real-time decision overhead
3Measurement precision
If beam mapping configuration is provided through RRC signaling, then mapping accuracy is improved with explicit beam associations, but signaling overhead increases due to detailed configuration messages
Solution Approach 1:
The patent implements a dynamic beam mapping configuration mechanism where the network can switch between RRC signaling and MAC CE based on the complexity and frequency of beam mapping changes. For semi-static scenarios, RRC signaling provides comprehensive configuration; for dynamic adjustments, MAC CE provides lightweight updates without full reconfiguration overhead
Solution Approach 2:
The beam mapping configuration is segmented into different levels: core beam associations are configured through RRC signaling for stability, while finer-grained adjustments and temporary mappings are handled through MAC CE. This segmentation allows the system to maintain accurate beam associations while minimizing overall signaling overhead by using the lighter MAC CE format for routine adjustments
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for associating transmit beams and sensing beams for channel access. One apparatus (700) includes a transceiver (725) and a processor (705) that receives (905) a mapping configuration from a RAN, said the mapping configuration associating at least one transmit beam to at least one sensing beam. The processor (705) receives (910) an indication of a transmit beam to perform uplink transmission and determines (915) a sensing beam based on the indicated transmit beam and the mapping configuration. Via the transceiver (725), the processor (705) performs (920) an LBT procedure prior to transmission using the determined sensing beam, where the determined sensing beam has a beamwidth that covers the indicated transmit beam, and performs (925) uplink transmission during a COT using at least the indicated transmit beam in response to LBT success.