Early CSI Reporting in RACH Msg3 for Beam Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In New Radio (NR) networks up to Release 16, User Equipment (UE) selects a Physical Random Access Channel (PRACH) preamble associated with a Serving Signal-Restricted Resource (SSR) with sufficient Signal-Restricted Resource (SRP) but not necessarily the best, and there is no dedicated signaling for early Channel State Information (CSI) reporting before a Radio Resource Connection (RRC) is established, limiting efficient data transmission and beam adjustment.
Innovation Solution
The UE reports the best 'N' Synchronization Signal/Physical Broadcast Channel Resource Indicator (SSBRI) and/or Channel State Information Reference Signal (CSI-RS) Resource Indicator (CRI) in an early CSI report during the 4-step or 2-step Random Access Channel (RACH) procedure, allowing the network to adjust beams and determine transmission parameters based on this information, with configuration options in System Information Block 1 (SIB1) and the Random Access Response (RAR) message.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE selects PRACH preamble associated with SSB with sufficient SRP, then random access can be initiated, but the selected SSB may not be the best one and no early CSI reporting is available
Solution Approach 1:
The patent applies preliminary action by enabling the UE to report CSI (including SSBRI and RSRP) in Msg3 before the RRC connection is established. This early CSI reporting allows the network to identify the best SSB beam in advance and make informed beam adjustment decisions during the random access procedure, rather than waiting until after connection establishment.
2Productivity
If early CSI reporting is implemented, then beam adjustment and transmission parameter optimization can be performed, but additional signaling overhead is required
Solution Approach 1:
The patent applies universality by utilizing the existing Msg3 message in the random access procedure to carry CSI reporting information. Instead of creating a separate dedicated signaling mechanism, the invention repurposes the uplink shared channel resources already allocated for Msg3 transmission to also convey CSI data, thereby achieving early CSI reporting without requiring additional dedicated signaling overhead.
3Measurement precision
If UE reports best N SSBRI and CRI in early CSI report, then network can optimize beam and transmission parameters, but Msg3 payload size increases
Solution Approach 1:
The patent applies the taking out principle by extracting only the most essential CSI elements (best N SSBRI and corresponding RSRP values) for reporting in Msg3. Rather than reporting complete CSI including all possible measurements and detailed channel state information, the invention selectively extracts the critical beam identification and quality metrics needed for immediate beam adjustment decisions, thereby minimizing payload size while maintaining effectiveness.
Data Source
AI summary
This disclosure relates to Random Access (RA) procedures in communication networks, and in particular relates to the 4-step RA procedure and the 2-step RA procedure. The techniques described herein more specifically relate to the content of a channel state information report in a random access procedure. A method performed by a wireless device in a random access, RA, procedure comprises performing measurements of one or more reference signals transmitted by abase station. The method further comprises sending a first message to the base station in a Physical Uplink Shared Channel, PUSCH. The first message comprises a Channel State Information, CSI, report comprising information based on the measurements of the one or more reference signals.