RACH Occasion Selection Across Uplink and SBFD Symbols
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Solution Overview
Problem
Legacy UEs not capable of subband full-duplex (SBFD) operation experience increased RACH collision probability and latency due to inability to use ROs configured in SBFD symbols, while SBFD-aware UEs can reduce latency but may not utilize uplink symbols efficiently.
Innovation Solution
Implementing a rule or indication for UEs to prioritize RO selection in SBFD symbols over uplink symbols based on specific triggering events or SSB directions, ensuring efficient use of SBFD resources and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If legacy UEs use only uplink symbols for RACH transmission, then compatibility is maintained, but RACH collision probability increases and latency increases
Solution Approach 1:
The patent segments RACH occasions into two distinct types: those in uplink symbols and those in SBFD symbols. Legacy UEs are assigned only uplink symbol ROs, while SBFD-aware UEs can use SBFD symbol ROs. This segmentation resolves the contradiction by maintaining compatibility for legacy UEs while providing low-latency access for advanced UEs through separate resource pools.
Solution Approach 2:
The patent introduces a new dimension to RACH resource selection by utilizing the duplexing mode dimension. Instead of all UEs competing for the same uplink symbol resources, SBFD-aware UEs access an additional dimension (SBFD symbols) that legacy UEs cannot use. This dimensional expansion reduces collisions while maintaining backward compatibility.
2Loss of time
If SBFD-aware UEs use SBFD symbols for RACH transmission, then latency is reduced, but uplink symbol resources may be underutilized
Solution Approach 1:
The patent enables SBFD-aware UEs to self-select appropriate RACH occasions based on their capabilities and current conditions. These UEs can autonomously choose SBFD symbol ROs when available, reducing latency without requiring network intervention. Meanwhile, uplink symbol ROs remain available for legacy UEs and SBFD-aware UEs when needed, ensuring continuous utilization of uplink resources.
Solution Approach 2:
The patent changes the parameter of symbol type used for RACH transmission from a single fixed option to a variable selection between uplink and SBFD symbols. This parameter change allows the system to optimize latency for SBFD-aware UEs while maintaining flexibility in uplink symbol usage patterns, preventing resource underutilization.
3Manufacturing precision
If separate power control configurations are provided for SBFD and uplink ROs, then transmission accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments power control configurations into separate parameters for SBFD ROs and uplink ROs. This segmentation allows precise, independent optimization of transmit power for each RO type without cross-interference. While it increases the number of parameters, each parameter remains simple and clearly defined, making implementation straightforward despite the additional complexity.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive one or more random access channel (RACH) configurations that indicate RACH occasions (ROs). The UE may transmit a physical RACH (PRACH) message in an RO based at least in part on a rule or an indication. Numerous other aspects are described.