RC UE Random Access Preamble Grouping for NR Initial Access
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Solution Overview
Problem
The 3GPP NR system lacks a specific method for supporting random access by Reduced Capability (RC) user equipment (UE), particularly in identifying and optimizing resource utilization for RC UEs during initial access and random access preamble transmission.
Innovation Solution
A method and apparatus for RC UEs in a wireless communication system that involves receiving random access configuration information, determining RACH occasion groups and random access preamble groups based on UE type and repetition level, and transmitting preambles in these groups to enable identification and optimized resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a new random access method for RC UE is introduced, then identification and support of RC UE during initial access is improved, but device complexity and system configuration complexity increase
Solution Approach 1:
The random access procedure is segmented into distinct phases: RC UE identification during preamble transmission, determination of repetition level based on identification, and configuration of RACH occasions and preambles based on repetition level. This segmentation allows the system to handle RC UE specifically without complicating the entire random access mechanism.
Solution Approach 2:
The base station performs preliminary identification of RC UE during the random access preamble transmission phase, before full random access configuration is established. This preliminary action enables the system to prepare appropriate repetition levels and RACH occasion configurations in advance, reducing overall system complexity.
2Reliability
If repetition level determination is based on RC UE identification, then coverage compensation for RC UE is improved, but processing time and signaling overhead increase
Solution Approach 1:
The base station determines the repetition level in advance based on RC UE identification during preamble transmission, before the actual random access procedure begins. This preliminary determination of repetition level eliminates the need for iterative adjustments during the random access process, reducing processing time.
Solution Approach 2:
The RC UE self-identifies through its preamble transmission characteristics, allowing the base station to automatically determine the appropriate repetition level without additional signaling or manual configuration. This self-service mechanism reduces both processing time and signaling overhead.
3Productivity
If RACH occasions and preambles are determined based on repetition level, then resource optimization for RC UE is improved, but system complexity and configuration overhead increase
Solution Approach 1:
Different RACH occasions and preamble configurations are assigned to different repetition levels locally, rather than using a uniform configuration for all UEs. This local quality approach optimizes resources for each RC UE based on its specific repetition level requirements without requiring complex global reconfiguration.
Solution Approach 2:
The system changes key parameters (RACH occasion timing, frequency resources, preamble formats) based on the determined repetition level. These parameter changes enable resource optimization for RC UE while maintaining a relatively simple configuration structure that can be managed through standardized procedures.
Data Source
AI summary
Disclosed is a random access method and apparatus for a reduced capability user equipment in a wireless communication system. A method of performing random access by a UE in a wireless communication system according to an embodiment of the disclosure may include an operation of receiving random access-related configuration information from a base station; an operation of determining at least one of a RACH occasion (RO) group related to random access preamble transmission, one or more ROs, and a random access preamble group based on at least one of the random access-related configuration information, a UE type, and a repetition level; and an operation of transmitting one or more random access preambles in each of the one or more ROs.