Adaptive PRACH Preamble Formats for Low-Power UE Access
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Solution Overview
Problem
Current random-access procedures in 5G NR networks, particularly in non-terrestrial networks, face inefficiencies due to a one-size-fits-all approach to preamble formats, leading to increased latency, resource bottlenecks, and higher failure rates for UEs with limited transmission power, especially in large cells and satellite communications.
Innovation Solution
Implementing a method and apparatus that allow for multiple PRACH preamble formats with associated repetitions, enabling different UEs to use varying preamble formats and resources within a cell, optimizing resource allocation and reducing contention-based collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a one-size-fits-all preamble format is used in random-access procedures, then device complexity is reduced and ease of operation is improved, but resource utilization deteriorates and latency increases due to bottlenecks in large cells and for UEs with limited transmission power
Solution Approach 1:
The patent segments the random-access procedure by introducing multiple preamble formats (short and long preambles) with different characteristics. Short preambles are used for UEs with good channel conditions and low latency requirements, while long preambles are used for UEs with limited transmission power or in large cells. This segmentation allows the system to optimize resource utilization for different UE types without compromising ease of operation, as the network node automatically selects the appropriate format based on UE capabilities and channel conditions.
2Device complexity
If a single preamble format is used for all UEs, then device complexity is reduced, but latency increases and random-access success rate deteriorates for UEs with limited transmission power in large cells
Solution Approach 1:
The patent applies local quality by assigning different preamble formats to different UEs based on their specific characteristics and channel conditions. UEs with limited transmission power or located at cell edges use long preambles with higher energy distribution and better correlation properties, while UEs with sufficient power use short preambles. The network node determines the appropriate format based on UE power capabilities, channel quality indicators, and random-access configuration information, thereby optimizing random-access success rate for each UE without increasing device complexity.
3Reliability
If multiple preamble formats with repetitions are implemented, then random-access success rate for low-power UEs is improved and resource utilization is enhanced, but device complexity increases and ease of operation deteriorates
Solution Approach 1:
The patent implements self-service by enabling the network node to automatically manage the complexity of multiple preamble formats. The network node receives random-access configuration information indicating available preamble formats, determines the appropriate format based on UE power capabilities and channel conditions, and provides timing advance commands to synchronize UE transmissions. This automation eliminates the need for UEs to complexly manage multiple formats, maintaining ease of operation while improving random-access success rate through format diversity and repetitions for low-power UEs.
Data Source
AI summary
A method performed by a user equipment (UE) (3) is provided. The method includes: receiving, from an access network node (5, 9), random-access configuration information identifying a plurality of physical random-access (PRACH) preamble formats for use by the UE (3) in a random-access procedure. Each of the plurality of the PRACH preamble formats is associated with a respective resource within a period to which the random-access configuration information is applicable. The each of the plurality of the PRACH preamble formats is associated with a respective number of repetition.