Multi-TRP RACH MSG1 Transmission Using FDM and SDM
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 5G NR wireless communication systems face inefficiencies in the random access channel (RACH) procedure when multiple transmission/reception points (TRPs) are involved, leading to suboptimal performance in message transmissions.
Innovation Solution
Implementing frequency division multiplexing (FDM) and spatial division multiplexing (SDM) to allow simultaneous message transmissions (MSG1) with multiple TRPs during the RACH procedure, using a RACH configuration that identifies multiple sets of reference signals (RSs) for each TRP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sequential message transmissions are used in RACH procedure with multiple TRPs, then device complexity is reduced, but productivity deteriorates due to increased latency and fewer simultaneous connections
Solution Approach 1:
The patent segments the RACH procedure by allowing different messages (MSG1, MSG3) to be transmitted simultaneously to different TRPs using different spatial beams. This segmentation enables parallel processing at the network side while keeping UE complexity manageable through structured resource allocation and beam management.
Solution Approach 2:
The patent introduces spatial dimension (SDM) and frequency dimension (FDM) to enable simultaneous transmissions. By utilizing multiple spatial beams and frequency resources, the system transforms sequential transmissions into parallel transmissions across different dimensions, improving productivity without proportionally increasing complexity.
2Loss of time
If simultaneous message transmissions with multiple TRPs are implemented, then productivity improves through parallel communications, but device complexity increases due to multiple reference signals and resource management
Solution Approach 1:
The patent applies preliminary action by configuring multiple reference signals (CSI-RS, SSB) and their associated TRP identifiers before the RACH procedure begins. The UE performs measurements and selects appropriate reference signals in advance, which simplifies the actual transmission process and reduces real-time complexity while enabling simultaneous transmissions.
Solution Approach 2:
The patent implements feedback mechanisms where the UE measures reference signals from multiple TRPs, selects the best ones, and reports measurements to the network. This feedback loop enables the network to optimize resource allocation and beam selection, reducing complexity through intelligent decision-making based on channel conditions.
3Reliability
If multiple reference signals are configured for different TRPs, then reliability improves through diverse transmission paths, but device complexity increases due to measurement and selection overhead
Solution Approach 1:
The patent applies local quality by associating specific reference signals with specific TRPs and spatial beams. Each reference signal is optimized for its corresponding TRP's channel characteristics, allowing the UE to select the most appropriate local resource for each transmission, thereby improving reliability without requiring complex global optimization.
Data Source
Figure 1
Figure 2A~2D
Figure 3
AI summary
In an aspect, the present disclosure includes a method, apparatus, and computer readable medium for wireless communications at a UE, comprising receiving a RACH configuration from a network entity of a primary cell, the RACH configuration identifies at least two sets of RSs each corresponding to one of at least two different TRPs of a secondary cell; measuring one or more transmissions on each of the at least two sets of RSs for the at least two different TRPs; selecting at least a pair of RSs from the at least two different TRPs for a RACH procedure based on measuring the one or more transmissions; and transmitting a MSG1 of the RACH procedure with at least the pair of RSs on at least two allocated RACH occasions simultaneously to each TRP of the at least two different TRPs using at least one of FDM and SDM.