Multi-Band LBT Resource Selection for Reliable Random Access
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Solution Overview
Problem
In existing communication systems, the use of unlicensed bands for random access is hindered by LBT failures, leading to delays and failures in random access procedures due to simultaneous initiation of multiple parallel access attempts being disallowed, especially in dual connectivity scenarios.
Innovation Solution
A method and device that perform LBT operations on multiple RO resources across different LBT frequency bands, selecting successful target RO resources for preamble transmission, and utilizing contention-free random access resource configurations to enhance the probability of successful random access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple parallel random access attempts are initiated simultaneously, then the probability of successful random access is improved, but LBT failures cause delays and failures in the random access procedure
Solution Approach 1:
The patent segments the random access procedure by separating CFRA resource selection from LBT operations. The terminal first determines CFRA resources from a configured set, then performs LBT separately on each selected resource's associated frequency band. This segmentation allows parallel LBT operations on multiple frequency bands without simultaneous preamble transmission, resolving the contradiction between improving success probability and avoiding LBT-induced delays.
Solution Approach 2:
The patent applies preliminary action by having the network pre-configure multiple CFRA resources and their associated frequency bands before the random access procedure. The terminal performs LBT operations on these pre-selected frequency bands before actual preamble transmission, ensuring that channel access attempts are prepared in advance but executed sequentially based on LBT outcomes, thus improving reliability while managing time loss.
2Reliability
If multiple RO resources are used simultaneously for random access, then the probability of successful LBT operations is increased, but the complexity of resource management increases
Solution Approach 1:
The patent introduces CFRA resources as an intermediary layer between the terminal and LBT frequency bands. The network configures multiple CFRA resources, each associated with a specific frequency band. The terminal uses these intermediaries to systematically manage multiple RO resources by selecting CFRA resources first, then performing LBT on their associated frequency bands, which simplifies the complexity of directly managing multiple RO resources while maintaining high LBT success probability.
3Reliability
If LBT operations are performed on multiple frequency bands, then the likelihood of successful channel access is improved, but the time required for channel access increases
Solution Approach 1:
The patent segments the channel access process by dividing it into distinct phases: CFRA resource determination followed by LBT operations on specific frequency bands associated with selected CFRA resources. This segmentation allows the terminal to focus LBT efforts on fewer, pre-selected frequency bands rather than scanning all possible bands, improving the likelihood of successful access while reducing the total time required compared to exhaustive frequency band scanning.
Data Source
AI summary
A random access method includes: performing listen before talk (LBT) operations on LBT frequency bands corresponding to N physical random access channel occasion (RO) resources; and selecting M target RO resources from the N RO resources, at least two RO resources in the N RO resources being corresponding to different LBT frequency bands, the target RO resources being RO resources in the N RO resources at which LBTs are successful, N being an integer greater than 1, and M being an integer less than or equal to N and greater than or equal to 1; and sending preambles by using the M target RO resources.