Random Access Procedure BWP and SSB Selection for 5G NR-U
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Solution Overview
Problem
The success rate of Random Access (RA) procedures in wireless communication systems, particularly in next-generation 5G New Radio (NR) systems operating on unlicensed spectrum, is affected by increased failure rates of initial access and handover procedures due to challenges in accessing cells on unlicensed spectrum.
Innovation Solution
The solution involves an apparatus and method for performing RA procedures by selecting a suitable Bandwidth Part (BWP) and Synchronization Signal Block (SSB) with dedicated RA resources, transmitting a RA preamble, and setting the BWP as active upon successful RA, thereby optimizing RA resource allocation and signal quality thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If devices attempt to access cells on unlicensed spectrum, then spectrum utilization is promoted, but the success rate of RA procedures decreases
Solution Approach 1:
The patent segments the RA procedure into multiple independent attempts across different BWPs. Instead of relying on a single BWP for RA, the system divides the access process into multiple parallel opportunities (first BWP, second BWP, etc.), where each BWP can independently handle RA attempts. This segmentation allows the system to maintain high spectrum utilization while improving reliability through diversified access paths.
Solution Approach 2:
The patent changes the parameter of BWP selection dynamically during the RA procedure. When the first RA attempt on the first BWP fails, the system transitions to a second BWP for the second RA attempt. This parameter change (switching BWP) allows the system to adapt to varying channel conditions on unlicensed spectrum, thereby maintaining both high spectrum utilization and improved RA success rate.
2Reliability
If dedicated RA resources are prioritized, then RA procedure success rate is enhanced, but resource allocation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple BWPs with dedicated RA resources before the RA procedure begins. The network pre-establishes the first BWP, second BWP, and their associated RA resources, so that when RA is needed, the device can immediately select from pre-prepared options without complex real-time allocation decisions. This reduces runtime complexity while ensuring high RA success rate through dedicated resources.
Data Source
AI summary
A method performed by an apparatus of wireless communications is provided. The method includes receiving a plurality of Random Access (RA) configurations associated with a set of Bandwidth Parts (BWPs), selecting a first BWP from the set of BWPs to perform an RA procedure, and selecting a first Synchronization Signal Block (SSB) associated with the first BWP. The first SSB may be configured with a first RA resource. The method further includes transmitting a first RA preamble using the first RA resource and setting the first BWP as a first-activated BWP when the RA procedure is successfully performed.