Dynamic RACH Configuration for Radar Interference Mitigation
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Solution Overview
Problem
5G cellular networks face challenges in coexisting with high-power narrowband interferers like RADARs, leading to unreliable random-access failures due to interference with resource blocks, affecting RACH preamble transmission and reception.
Innovation Solution
The implementation of dynamic RACH configuration management, where WTRUs switch to a secondary RACH configuration upon detection of interference, retrieved from System Information Blocks (SIB) or RAR messages, to ensure robust and efficient preamble transmission and reception, including frequency domain resource reconfiguration and power boosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RACH preambles are transmitted on resource blocks that overlap with RADAR frequency, then the resource blocks can be utilized for 5G access, but the gNB cannot receive the preambles reliably due to high interference
Solution Approach 1:
The patent implements dynamic RACH configuration where the gNB can switch between a first RACH configuration (which may overlap with RADAR) and a second RACH configuration (which avoids RADAR interference). The gNB receives indication information about RADAR presence and dynamically selects the appropriate configuration, allowing the system to adapt to changing interference conditions and maintain reliable preamble reception.
Solution Approach 2:
The patent changes the frequency domain parameters of the RACH configuration based on RADAR interference detection. When RADAR is detected, the gNB switches to a second configuration with different frequency resources (different msg1-FrequencyStart and/or msg1-FDM parameters), effectively moving the RACH transmissions to interference-free frequencies while maintaining the same access functionality.
2Ease of operation
If RACH preambles are transmitted in the presence of RADAR interference, then random access can proceed, but the preambles may interfere with RADAR operations
Solution Approach 1:
The patent applies local quality by making the RACH configuration specific to the interference environment. Different RACH configurations are defined for different frequency regions - one for areas without RADAR and another for areas with RADAR. The gNB selects the appropriate configuration based on local RADAR presence, ensuring that RACH transmissions in RADAR-affected areas do not interfere with RADAR operations while maintaining random access availability.
3Device complexity
If a single RACH configuration is used, then the system is simple to manage, but it cannot adapt to RADAR interference conditions
Solution Approach 1:
The patent implements multi-functionality by creating a universal RACH configuration management system that handles both RADAR and non-RADAR scenarios. The gNB is equipped with multiple RACH configurations and the capability to select between them based on interference conditions. This universal system maintains simplicity for normal operation (using the first configuration) while providing adaptability when RADAR interference is detected (switching to the second configuration).
Data Source
AI summary
A wireless transmit receive unit (WTRU) and methods are disclosed for mitigating radar interference with transmission and reception of RACH preambles. According to a first aspect, one or more first RACH preambles are transmitted based on a first RACH configuration. The WTRU may receive an RAR with an indication that the first RACH configuration is unavailable. The WTRU may then retrieve a second RACH configuration information. The WTRU may then transmit one or more second RACH preambles based on the second RACH configuration and then completes a random access procedure based on the second RACH configuration.