RSRP-Based PRACH Preamble Selection for Cell-Edge Access

The patent segments the random access procedure by introducing multiple RSRP thresholds (first threshold for SSB selection, second threshold for preamble selection) and dividing preambles into different groups. This segmentation allows cell-edge UEs to follow a optimized path through the random access procedure, reducing latency while maintaining extended coverage capability.

The patent changes key parameters including introducing dual RSRP thresholds, dividing preambles into multiple groups with different selection criteria, and allowing UEs to switch between different random access procedures based on measured RSRP values. These parameter changes enable adaptive random access that reduces latency for cell-edge UEs while preserving coverage extension.

The patent applies preliminary action by pre-configuring multiple RSRP thresholds and preamble groups through system information broadcasting before the random access procedure. UEs receive and store these configurations in advance, so during actual random access they only need to measure RSRP and select according to predefined rules, reducing real-time processing complexity while maintaining high efficiency.

The patent enables self-service by allowing UEs to autonomously measure RSRP, compare against configured thresholds, and select appropriate SSBs and preambles based on their own channel conditions. The network only needs to broadcast the threshold and group configurations, after which UEs independently complete the optimized random access selection without additional network intervention, reducing overall system complexity.