Multi-Set Random Access Resources for Reduced-Capability UEs
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Solution Overview
Problem
Reduced capability UEs face challenges in accessing a 5G NR system due to their narrower working bandwidth and fewer antennas, leading to reduced uplink and downlink transmission performance and a smaller maximum coverage radius, making it less likely for them to successfully complete a contention-based random access procedure.
Innovation Solution
Configuring multiple random access channel resource sets with varying coverage recovery levels and transmission parameters tailored for both full and reduced capability UEs, including different measurement thresholds, PDCCH search spaces, and repetitive CORESETs, to enhance the likelihood of successful random access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reduced capability UEs use standard contention-based random access procedure, then they can attempt to access the network, but their success rate is low due to narrower working bandwidth and fewer antennas
Solution Approach 1:
The random access channel resources are segmented into multiple resource sets with different coverage recovery levels. Reduced capability UEs can select from multiple PRACH occasion sets (first set, second set, etc.) corresponding to different coverage enhancement levels, allowing them to choose resources matched to their specific capability rather than using a single standardized approach.
Solution Approach 2:
Different parameter configurations are applied to different PRACH resource sets, including different measurement thresholds (e.g., first measurement threshold for first set, second measurement threshold for second set), different repetition numbers, and different transmission opportunities. This allows reduced capability UEs to operate with parameters optimized for their narrower bandwidth and fewer antennas.
2Reliability
If multiple RACH resource sets with different coverage recovery levels are provided, then reduced capability UEs can find suitable resources, but the device complexity and configuration overhead increase
Solution Approach 1:
The network pre-configures multiple PRACH resource sets with different coverage recovery levels before the random access procedure begins. Reduced capability UEs are provided with indication information about available resource sets and their corresponding measurement thresholds in advance, allowing them to make informed selections without real-time complex calculations or interactions.
Solution Approach 2:
Reduced capability UEs autonomously select appropriate PRACH resource sets based on their own capability indicators and the pre-provided configuration information. The UE independently determines which measurement threshold to use and which resource set to access without requiring complex network coordination or additional signaling during the random access procedure.
Data Source
AI summary
This disclosure relates to method and device for random access. In one implementation, the method may include obtaining a plurality of random access channel resource sets. The method may further include selecting a first random access channel resource set from the plurality of random access channel resource sets. The method may further include transmitting a random access preamble on the first random access channel resource set.