Repetition-Mode Random Access for 5G Uplink Coverage
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Solution Overview
Problem
The uplink coverage problem in 5G wireless communication systems, particularly due to the use of high frequency bands, necessitates enhancements to ensure effective random access and data transmission.
Innovation Solution
The method involves receiving first and second RACH configurations, selecting an uplink based on RSRP thresholds, transmitting preambles in available PRACH occasions, monitoring PDCCH in designated search spaces, and transmitting Msg3 based on time domain resource allocations within the uplink grant to optimize random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high frequency bands (mmWave) are used to achieve high data rates in 5G systems, then data transmission speed is improved, but uplink coverage is deteriorated due to increased propagation loss
Solution Approach 1:
The random access procedure is segmented into multiple configurable stages with different RACH configurations. The system divides the uplink transmission into normal uplink and supplementary uplink with separate RACH settings, allowing optimization for different coverage scenarios while maintaining high data rate capabilities
Solution Approach 2:
The system changes multiple parameters including RSRP thresholds, PRACH occasions, PDCCH search spaces, and time domain resource allocations to adapt to different uplink coverage conditions. By dynamically adjusting these parameters based on measured signal strength and network configuration, the system maintains reliable connection establishment while utilizing high frequency bands for high data rates
2Adaptability or versatility
If multiple RACH configurations are maintained for different uplink scenarios, then adaptability to various coverage conditions is improved, but system complexity increases
Solution Approach 1:
The system dynamically selects between different RACH configurations based on real-time conditions. The UE determines which RACH configuration to use by evaluating RSRP measurements against configured thresholds and selecting the appropriate uplink (normal or supplementary) and corresponding RACH settings, making the system adaptable without requiring manual reconfiguration
Solution Approach 2:
The system enables self-service through autonomous configuration selection. The UE automatically selects the appropriate RACH configuration, monitors the correct PDCCH search spaces, and adjusts transmission parameters based on received RAR messages without network intervention, reducing the operational complexity despite maintaining multiple configurations
Data Source
AI summary
A method and apparatus for random access in repetition mode is provided. Method for random access in repetition mode includes receiving first RACH configuration, second RACH configuration and PDCCH configuration, selecting an uplink on which to perform a random access procedure based on the first RSRP threshold in the first RACH configuration, transmitting a preamble in the next available PRACH occasion based on PRACH configuration index, monitoring PDCCH in search space indicated by random access search space during while random access window is running, receiving a random access response message including a preamble identifier related to the preamble transmission and transmitting Msg3 based on the time domain resource allocation field in the uplink grant in the random access response.