RACH Resource Selection Using SRS for Cross-Link Interference Mitigation
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Solution Overview
Problem
Wireless communication systems face interference issues, particularly cross-link interference (CLI), during random access channel (RACH) procedures when operating in full duplex mode, which can impact connection establishment and configuration.
Innovation Solution
Communication devices measure and report CLI using reference signals, such as SRS, to select optimal RACH occasions based on signal strength, enabling the network to adjust resources to mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full duplex mode is used for random access channel procedures, then spectrum efficiency is improved, but cross-link interference increases
Solution Approach 1:
The patent applies preliminary action by having the UE perform CLI measurement before the RACH procedure to determine whether to use a full duplex RO. The UE measures the reference signal in advance, compares the signal strength against a threshold, and only proceeds with full duplex RACH if the measurement indicates acceptable interference levels, thereby preventing harmful interference before it occurs.
Solution Approach 2:
The patent implements feedback by having the UE report CLI measurement results to the network, which then provides feedback in the form of a bitmap indicating which ROs are suitable for full duplex operation. This feedback mechanism allows the system to adapt and select appropriate ROs based on actual interference conditions, balancing spectrum efficiency with interference mitigation.
2Reliability
If CLI measurement is performed before RACH procedure, then interference mitigation is improved, but latency increases
Solution Approach 1:
The patent applies preliminary action by performing CLI measurement in advance before the RACH procedure, allowing the UE to pre-determine suitable ROs. This advance preparation enables faster RACH execution without the need for real-time measurement during the critical access phase, thus reducing overall latency while maintaining reliability.
Solution Approach 2:
The patent applies partial action by performing CLI measurement only for specific ROs that are candidates for full duplex operation, rather than measuring all possible ROs exhaustively. This selective measurement approach reduces the time required for interference assessment while still providing sufficient information to make informed decisions about RO selection.
3Productivity
If full duplex RACH is used, then productivity is improved, but harmful factors increase
Solution Approach 1:
The patent applies local quality by treating different ROs differently based on their interference characteristics. Instead of using a uniform approach for all ROs, the system identifies specific ROs with lower interference levels (based on CLI measurement) and designates them as suitable for full duplex operation, while avoiding full duplex for ROs with high interference. This localized differentiation optimizes productivity where safe and prevents harmful effects where risky.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the operational parameters of RACH procedures based on measured interference levels. The system changes the mode of operation (full duplex vs. half duplex) and selects appropriate ROs based on the CLI measurement results, thereby adapting the RACH procedure parameters to balance productivity gains with harmful effect mitigation.
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. A communication device may receive control signaling indicating a first set of resources for random access channel (RACH) occasions (ROs) and a second set of resources for communicating one or more indications of interference (e.g., crosslink interference (CLI)) associated with the ROs. The communication device may receive a reference signal (e.g., a sounding reference signal (SRS)) over at least one resource of the second set of resources. The communication device may perform a RACH procedure during an RO. The RO may be associated with the at least one resource and may be based on a signal parameter associated with the received reference signal satisfying a threshold (e.g., reference signal strength indicator (RSSI)).