Two-Step RACH Resource Pair Configuration for UE Adaptability
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing the two-step random access procedure for user equipment (UE) to achieve synchronization and obtain network resources, particularly in configuring suitable time gaps between physical random access channel (PRACH) and physical uplink shared channel (PUSCH) transmissions.
Innovation Solution
The system provides a method for user equipment (UE) to select a resource pair with a predetermined PRACH-to-PUSCH time gap for the two-step random access channel (RACH) procedure, allowing for flexible time gap configurations between PRACH and PUSCH transmissions, and enabling the UE to transmit a first RACH message comprising only a PRACH transmission if the configured time gap is not supported.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the system configures multiple resource pairs with different time gaps for PRACH and PUSCH transmissions, then the adaptability to different UE capabilities is improved, but the device complexity increases
Solution Approach 1:
The resource configuration is segmented into multiple resource pairs, where each pair consists of PRACH resources and PUSCH resources with a specific time gap. This segmentation allows the system to provide differentiated configurations for different UE capabilities without requiring a completely separate configuration system for each capability level.
Solution Approach 2:
The system changes the time gap parameter between PRACH and PUSCH resources to create multiple resource pairs. By varying this critical parameter, the system can accommodate different UE processing capabilities while maintaining a unified resource configuration framework, thus improving adaptability without proportionally increasing complexity.
2Reliability
If the UE selects a resource pair that satisfies the predetermined time gap requirement, then the reliability of the random access procedure is improved, but the loss of time for resource selection increases
Solution Approach 1:
The network performs preliminary configuration by pre-defining multiple resource pairs with different time gap characteristics before the UE needs to perform random access. This preliminary action allows the UE to quickly select from pre-evaluated options rather than performing complex real-time calculations, thus maintaining reliability while reducing selection time.
Solution Approach 2:
The UE is empowered to autonomously select the appropriate resource pair from the configured options based on its own capability assessment. This self-service approach eliminates the need for extensive network control and real-time negotiation, reducing the time loss for resource selection while ensuring the UE chooses a reliable configuration.
3Ease of operation
If the system supports UEs to transmit only PRACH without PUSCH when time gap requirements are not met, then the ease of operation is improved, but the productivity of the random access procedure decreases
Solution Approach 1:
The system allows UEs to perform partial action by transmitting only PRACH without PUSCH when the time gap requirement cannot be met. This partial transmission is sufficient to establish basic connectivity and synchronization, improving ease of operation for capability-constrained UEs. The PUSCH transmission can be deferred or omitted without preventing the random access procedure from completing its essential function.
Data Source
AI summary
A random access channel (RACH) procedure allows a user equipment (UE) to achieve synchronization with a network and obtain network resources and services from a scheduling entity. This disclosure provides various options for implementing a two-step RACH procedure that can support various UE behaviors in relation to using or not using a time symbol gap between a physical random access channel (PRACH) resource and a physical uplink control channel (PUCCH) resource.