SSB-Based RACH Occasion Validity in Subband Full-Duplex Slots
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Solution Overview
Problem
In wireless communications systems, there is ambiguity regarding the validity of random access channel (RACH) occasions (ROs) in subband full duplex (SBFD) slots, leading to interference and reduced spectral efficiency, increased power consumption, and poor user equipment (UE) performance.
Innovation Solution
Techniques for determining the validity of ROs in SBFD slots by processing synchronization signal blocks (SSBs) based on RACH and SBFD configurations, allowing valid ROs for RACH preambles to be transmitted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RACH occasions are configured in SBFD slots without validity determination, then spectral efficiency decreases and interference increases, but implementing validity determination requires additional processing complexity
Solution Approach 1:
The patent applies preliminary action by pre-determining the validity of RACH occasions in SBFD slots based on configuration parameters before actual RACH procedures are executed. The network entity pre-identifies which ROs are valid by checking against configured parameters (ssb-PositionsInBurst, messageWindow, msg1-FrequencyStart, msg1-CyclicShift, etc.), so that UEs can directly use these pre-determined valid ROs without performing complex real-time validity checks, thus improving spectral efficiency while maintaining manageable processing complexity.
Solution Approach 2:
The patent implements self-service by enabling the system to automatically determine RO validity through configured parameters without requiring additional signaling or manual intervention. The validity determination is performed self-service style by comparing RO configurations against SBFD slot parameters that are already part of the standard RACH configuration, eliminating the need for separate validity indication messages or additional processing overhead.
2Reliability
If all RACH occasions are treated as valid in SBFD slots, then UE performance improves due to more access opportunities, but interference increases and power consumption rises
Solution Approach 1:
The patent applies local quality by differentiating the validity status of individual RACH occasions within SBFD slots based on their specific configuration parameters. Instead of treating all ROs uniformly, the system evaluates each RO against the SBFD slot configuration (ssb-PositionsInBurst, messageWindow, msg1-FrequencyStart, msg1-CyclicShift) to determine its validity locally. This allows only the appropriate subset of ROs to be activated, improving UE performance for valid ROs while avoiding interference and unnecessary power consumption associated with invalid ROs.
3Productivity
If RACH occasion validity is strictly determined in SBFD slots, then interference is reduced and spectral efficiency improves, but the number of available RACH occasions decreases
Solution Approach 1:
The patent applies partial action by determining validity for only those RACH occasions that are configured in SBFD slots, rather than applying validity checks to all possible ROs system-wide. The system performs partial validity determination based on the specific configuration parameters provided (ssb-PositionsInBurst, messageWindow, msg1-FrequencyStart, msg1-CyclicShift), activating validity determination only where SBFD operation is configured. This approach improves spectral efficiency for the affected ROs while minimizing the impact on the overall number of available RACH occasions in non-SBFD slots.
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for validity of random access channel (RACH) occasions (ROs) in subband full duplex (SBFD) slots. An example method, performed at a user equipment (UE), generally includes receiving a random access channel (RACH) configuration and a subband full duplex (SBFD) configuration, wherein the RACH configuration indicates one or more RACH occasions (ROs) and the SBFD configuration indicates at least one SBFD slot, processing a synchronization signal block (SSB) mapped to at least one first RO of the one or more ROs, determining the at least one first RO in the at least one SBFD slot is valid, based on the RACH configuration, the SBFD configuration, and the mapping, and transmitting a RACH preamble on the at least one first valid RO.