Connected-Mode RACH Occasion Multiplexing for SBFD CLI Control
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Solution Overview
Problem
In sub-band full-duplex (SBFD) operations, random access channel (RACH) transmissions in uplink sub-bands cause UE-to-UE cross-link interference (CLI), leading to increased latency and collision probability, which affects the coverage and efficiency of random access in wireless communication systems.
Innovation Solution
Implementing conditions for random access in SBFD resources, including power control and signal conflict management, to optimize the use of SBFD ROs and reduce CLI, thereby enhancing UL coverage and reducing RACH collision probability and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RACH transmissions are performed in uplink sub-bands during SBFD operation, then UL coverage is enhanced, but UE-to-UE cross-link interference increases
Solution Approach 1:
The patent applies local quality by differentiating the treatment of RACH occasions based on their location and characteristics. Specifically, it identifies RACH occasions that would cause harmful CLI and excludes them from the set of valid RACH occasions for connected UEs, while allowing other RACH occasions to remain valid. This selective approach maintains UL coverage enhancement in areas where it is beneficial while preventing harmful interference in specific locations.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of a determination process that evaluates whether a RACH occasion would cause harmful CLI before including it in the valid set. This intermediary evaluation step acts as a filter between the potential RACH occasions and the actual ones used by connected UEs, mediating between the desire for UL coverage and the need to prevent interference.
2Productivity
If RACH transmissions are performed in SBFD resources, then random access efficiency is improved, but collision probability increases
Solution Approach 1:
The patent applies preliminary action by performing a determination step before allowing connected UEs to use certain RACH occasions. The network node determines in advance which RACH occasions would cause harmful CLI and excludes them from the valid set. This preliminary filtering action prevents potential collisions and interference before they occur, thereby maintaining random access efficiency while reducing collision probability.
Solution Approach 2:
The patent implements feedback through the network node's determination process that monitors and evaluates the impact of RACH occasions on CLI. The network node uses this feedback information to dynamically determine which RACH occasions should be excluded from the valid set for connected UEs, creating a closed-loop system that adapts to actual interference conditions to reduce collisions.
3Loss of time
If connected UEs are allowed to use SBFD ROs, then latency is reduced, but harmful CLI is generated
Solution Approach 1:
The patent applies local quality by making differentiated allowances for different types of UEs and different RACH occasions. Connected UEs are allowed to use SBFD ROs for purposes other than random access, and can use certain RACH occasions that do not cause harmful CLI. The patent specifically excludes only those RACH occasions that would generate harmful interference, while allowing others to proceed, thus reducing latency where possible while preventing harmful CLI where necessary.
Data Source
AI summary
The apparatus may be a UE configured to receive time and frequency information for SBFD resources, receive a random access configuration for random access in the SBFD resources, and transmit, based on meeting one or more conditions of a random access event trigger condition, a power condition, a UE type condition, or a conflicting signal condition, a random access message in a random access occasion (RO) in an uplink sub-band of an SBFD time period. The apparatus may be a network device configured to provide time and frequency information for SBFD resources and provide at least one random access configuration for random access in the SBFD resources, where the random access configuration is associated with one or more conditions of a random access event trigger condition, a power condition, a UE type condition, or a conflicting signal condition.