PRACH Repetition Configuration for Cell-Edge Random Access
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Solution Overview
Problem
In 5G networks, cell-edge UEs experience delays due to poor connectivity during the random access procedure, necessitating improved PRACH resource design for UEs with varying pathloss values to enhance coverage.
Innovation Solution
A method for configuring PRACH resources with repetitions, specified by a set of parameters including a starting preamble, number of consecutive preambles, and PRACH repetitions, is implemented in both user equipment and base stations to optimize random access for enhanced coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PRACH resources are optimized for cell-edge UEs with repetitions, then connectivity and coverage are enhanced, but device complexity and configuration overhead increase
Solution Approach 1:
The patent changes the parameter configuration by introducing a set of parameters (starting preamble index, number of consecutive preambles, number of PRACH repetitions) that define a preamble partition. This allows dynamic adjustment of PRACH resources for different UE types without fundamentally changing the random access mechanism, thereby improving connectivity for cell-edge UEs while keeping the system manageable through parameterization rather than structural complexity
Solution Approach 2:
The patent segments the PRACH resources by creating a preamble partition that separates preambles for normal UEs from those for enhanced coverage UEs. This segmentation is achieved by allocating specific ranges of preamble indices to different UE categories, allowing targeted optimization for cell-edge UEs without affecting the overall random access procedure for all UEs, thus improving reliability for specific users while maintaining system-wide simplicity
2Loss of time
If PRACH repetitions are configured for enhanced coverage, then latency is reduced for cell-edge UEs, but resource allocation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the PRACH repetition parameters and preamble partitions through system information broadcast before the random access procedure begins. Cell-edge UEs can directly use the pre-configured repetitions without needing dynamic scheduling or complex real-time resource allocation, thereby reducing latency while avoiding the complexity of on-the-fly resource management
Solution Approach 2:
The patent uses parameter changes to control the number of PRACH repetitions through a configurable parameter set. By adjusting the number of repetitions parameter, the system can optimize latency for enhanced coverage UEs without requiring complex resource allocation algorithms, as the repetition count is determined by simple parameter configuration rather than complex scheduling decisions
Data Source
AI summary
A user equipment (UE) is described. The UE may comprise reception circuitry configured to receive system information including RACH configuration information, wherein the RACH configuration information includes a set of parameters including a parameter which specifies the number of PRACH repetitions; and control circuitry configured to apply the set of parameters when performing random access.