PRACH Occasion Group Selection for Wireless Uplink Coverage
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Solution Overview
Problem
The challenge in wireless communication systems is to optimize the determination of the target PRACH occasion group for improving uplink coverage and reducing transmission delay during PRACH transmissions.
Innovation Solution
A method in a first node for wireless communications involves receiving multiple reference signals, selecting a first reference signal, determining a target PRACH occasion group, and transmitting a random access preamble in that group. The target PRACH occasion group is randomly selected from a set with equal probability, ensuring each group comprises K PRACH occasions, where K is greater than 1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PRACH occasions are used to transmit random access preamble, then uplink coverage is improved, but transmission delay increases
Solution Approach 1:
The patent divides the PRACH occasions into multiple groups (first PRACH occasion group set) where each group contains multiple PRACH occasions. The UE randomly selects one group from the set, and within the selected group, transmits the random access preamble across multiple PRACH occasions. This segmentation allows the system to benefit from multiple transmission opportunities (improving coverage) while the random group selection prevents systematic delays (managing transmission delay).
Solution Approach 2:
The patent introduces dynamic random selection of PRACH occasion groups at the UE side. Instead of a fixed mapping between SSB and PRACH occasions, the UE randomly selects a group from the first PRACH occasion group set. This dynamic approach allows flexibility in adapting to different channel conditions and reduces the impact of delay variability, resolving the contradiction between needing multiple transmissions for coverage and minimizing delay.
2Reliability
If PRACH occasion groups are configured with multiple PRACH occasions, then transmission performance is improved, but resource utilization complexity increases
Solution Approach 1:
The patent creates a universal first PRACH occasion group set that can serve multiple SSBs. Each PRACH occasion group in the set contains multiple PRACH occasions that can be used for random access preamble transmission associated with different SSBs. This multi-functional structure improves transmission performance by providing multiple opportunities while maintaining manageable complexity through a unified group structure that can be applied across different SSB configurations.
Data Source
AI summary
A first receiver receives at least one of multiple reference signals; and selects a first reference signal, the first reference signal being one of the multiple reference signals; a first transmitter determines a target PRACH occasion group; and transmits a first random access preamble in the target PRACH occasion group; herein, the determining a target PRACH occasion group comprises: determining a first element from a first set; the first set comprises multiple elements, and each element in the first set comprises at least one PRACH occasion mapped to the first reference signal; the determining a target PRACH occasion group comprises: randomly selecting a PRACH occasion group from a first PRACH occasion group set with equal probability; each PRACH occasion group in the first PRACH occasion group set is mapped to the first reference signal, each PRACH occasion group in the first PRACH occasion group set comprises K PRACH occasions.