Shared PRACH Random Access Signaling for RedCap UEs
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in performing random access procedures for devices with varying maximum UE bandwidths, particularly for Reduced Capability (RedCap) UEs, which have lower processing capabilities and bandwidths, leading to resource inefficiencies and potential misidentification during random access.
Innovation Solution
A method and apparatus are provided to enable efficient random access by allowing RedCap UEs to share PRACH resources with legacy UEs, using different RA-RNTIs and adjusting message transmission schedules, enabling RedCap UEs to transmit with relaxed processing times while maintaining resource efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PRACH resources are shared between legacy UEs and RedCap UEs, then resource efficiency is improved, but device identification and message differentiation become more difficult
Solution Approach 1:
The patent segments the random access response by using different RA-RNTI values for different UE types. Legacy UEs use RA-RNTI calculated from PRACH occasion parameters, while RedCap UEs use RA-RNTI calculated from PRACH occasion parameters plus a specific offset. This segmentation allows the system to maintain shared PRACH resources while enabling clear differentiation and proper message delivery to the correct UE type.
2Productivity
If RedCap UEs use the same PRACH preamble sequences as legacy UEs, then resource utilization is improved, but preamble collision and misidentification increase
Solution Approach 1:
The patent introduces RA-RNTI as an intermediary mechanism to resolve the conflict between sharing preambles and avoiding misidentification. While both legacy and RedCap UEs can use the same PRACH preamble sequences, the RA-RNTI calculation incorporates an offset for RedCap UEs, acting as a mediator that ensures proper message differentiation and delivery without requiring separate preamble sequences.
3Measurement precision
If RedCap UEs are given dedicated PRACH resources, then identification accuracy is improved, but resource efficiency deteriorates
Solution Approach 1:
The patent makes the PRACH resources universal by allowing both legacy UEs and RedCap UEs to access the same PRACH occasions and preamble sequences. The differentiation is achieved not through dedicated resources but through the RA-RNTI calculation mechanism, which incorporates an offset for RedCap UEs. This multi-functional approach allows a single set of PRACH resources to serve both UE types effectively.
4Device complexity
If RedCap UEs transmit with relaxed processing times, then device complexity is reduced, but random access procedure efficiency may deteriorate
Solution Approach 1:
The patent applies local quality by allowing RedCap UEs to have relaxed processing time requirements specifically for the random access procedure, while maintaining normal processing requirements for other operations. The network can identify RedCap UEs through the RA-RNTI offset and apply appropriate processing time expectations locally to these devices without affecting overall system efficiency or other UE types.
Data Source
AI summary
A base station according to an embodiment of the present invention may determine multiple different RA-RNTIs, and transmit message 2 for a random access response on the basis that: the base station supports not only a random access procedure of a first type terminal having a first maximum terminal bandwidth, but also a random access procedure of a second type terminal having a second maximum terminal bandwidth smaller than the first maximum terminal bandwidth; message 1 including a PRACH preamble has been detected on a PRACH resource shared between the first type terminal and the second type terminal; and at least one of PRACH preamble sequences for the first type terminal is reused for the second type terminal.