Random Access Preamble Repetition by CE Level in 5G Coverage Gaps
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Solution Overview
Problem
Existing 5G communication systems face challenges in efficiently supporting various services such as enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra reliability low latency communication (URLLC) due to the need for improved random access methods in mobile communication systems, particularly for terminals operating in shaded areas with limited coverage.
Innovation Solution
A method and device that involve measuring reference signal received power (RSRP) values based on synchronization signal blocks (SSBs) to identify a coverage enhancement (CE) level, and transmitting random access preambles accordingly, along with a base station processing these preambles to improve coverage and efficiency in random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a terminal in a shaded area transmits random access preambles using conventional methods, then the transmission may fail due to limited coverage, but increasing transmission power or repetitions may cause interference to other users or excessive energy consumption
Solution Approach 1:
The terminal determines coverage enhancement (CE) levels based on measured RSRP values and compares them with thresholds to dynamically adjust transmission parameters. Different CE levels correspond to different numbers of preamble repetitions and power levels, allowing the system to adapt transmission parameters to actual channel conditions rather than using fixed parameters for all terminals
Solution Approach 2:
The system dynamically adjusts the number of random access preamble repetitions and transmission power based on the determined CE level. Terminals in weaker coverage areas (higher CE levels) automatically transmit more repetitions with appropriate power levels, while terminals in better coverage areas use fewer repetitions with lower power, making the system adaptive to varying channel conditions
2Area of stationary object
If the system increases the number of random access preamble repetitions for terminals in shaded areas, then coverage is improved, but the access delay increases and system resources are consumed
Solution Approach 1:
The system changes the parameter of preamble repetition count based on CE levels. Terminals determine their CE level by comparing measured RSRP with thresholds, and each CE level maps to a specific repetition count. This allows terminals in shaded areas to use higher repetition counts for extended coverage, while terminals in coverage areas use lower repetition counts to minimize access delay
Solution Approach 2:
The coverage area is segmented into multiple CE levels (CE0, CE1, CE2, CE3) based on RSRP thresholds. Each segment has predetermined transmission parameters including repetition counts. This segmentation allows the system to provide differentiated transmission strategies for different coverage conditions, optimizing the balance between coverage extension and access delay for each segment
3Device complexity
If the system uses fixed transmission parameters for all terminals, then the system is simple to implement, but terminals in shaded areas cannot achieve reliable random access
Solution Approach 1:
The terminal autonomously determines its own CE level by measuring RSRP values and comparing them with configured thresholds. The terminal then selects appropriate transmission parameters (repetition count, power level) based on the determined CE level without requiring complex network configuration or manual intervention. This self-service mechanism enables terminals to adapt to their coverage conditions independently
Solution Approach 2:
The system introduces CE level parameters that terminals determine based on RSRP measurements. Different CE levels correspond to different transmission parameter sets (number of repetitions, power levels). This parameter change mechanism allows the system to maintain simple implementation while achieving reliable random access for terminals in shaded areas through adaptive parameter selection
Data Source
AI summary
The present disclosure relates to a communication technique for combining an IoT technology with a 5G communication system for supporting a higher data transmission rate than a 4G system, and a system therefor. The present disclosure can be applied to intelligent services (for example, smart homes, smart buildings, smart cities, smart cars or connected cars, health care, digital education, retail businesses, security and safety-related services, and the like) on the basis of 5G communication technologies and IoT-related technologies. A method for a terminal in a wireless communication system, according to the present disclosure, comprises: measuring reference signal received power (RSRP) values corresponding to respective synchronization signal blocks (SSBs) on the basis of a plurality of SSBs which have been transmitted by a base station; identifying a coverage enhancement (CE) level of the terminal on the basis of the measured RSRP values and at least one RSRP threshold; and transmitting at least one random access preamble to the base station on the basis of the identified CE level.