IoT Random Access Preamble Resource Selection by Coverage Level
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Solution Overview
Problem
In cellular based IoT systems, such as NB-IoT, the existing random access process is inefficient due to increased operation time and energy consumption when a terminal fails to perform random access and needs to change coverage classes or levels.
Innovation Solution
The proposed method involves sequentially using preamble resources in the random access process, considering performance for each level of subcarrier spacing and/or multi-tone configuration in each coverage class or level, allowing the terminal to change coverage classes or levels only when necessary, and optimizing resource selection based on channel state and multi-tone support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal changes coverage classes or levels when random access fails, then the random access success rate is improved, but the operation time and energy consumption increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple preamble resources with different coverage levels before random access attempts. When random access fails, the terminal can immediately switch to a pre-configured preamble resource with different coverage parameters without undergoing a full coverage class change procedure, thereby reducing the time penalty while maintaining improved success rate
Solution Approach 2:
The patent segments the preamble resources into multiple groups corresponding to different coverage levels (CL0, CL1, CL2, etc.), each with specific subcarrier spacing and multi-tone configurations. This segmentation allows the terminal to selectively attempt random access on appropriate segments based on current channel conditions, avoiding unnecessary coverage class changes and reducing operation time
2Reliability
If the terminal changes coverage classes or levels when random access fails, then the random access success rate is improved, but the energy consumption increases
Solution Approach 1:
The terminal performs preliminary configuration of multiple preamble resources with different coverage levels before random access attempts. When failure occurs, it can switch to alternative pre-configured resources without triggering energy-intensive coverage class reconfiguration procedures, thus maintaining improved success rate while limiting energy consumption increase
Solution Approach 2:
The patent changes physical layer parameters (subcarrier spacing, multi-tone configuration) of preamble resources associated with different coverage levels. By selecting appropriate parameter sets based on channel conditions and failure patterns, the terminal can improve success rate while avoiding the energy overhead of full coverage class changes
3Productivity
If the terminal sequentially uses preamble resources considering subcarrier spacing and multi-tone configuration, then the resource utilization is improved, but the device complexity increases
Solution Approach 1:
The patent implements dynamic selection among multiple preamble resources with different subcarrier spacing and multi-tone configurations. The terminal adapts its random access strategy based on channel conditions and previous attempt outcomes, sequentially trying different resource configurations. This dynamic approach improves resource utilization while keeping device complexity manageable through algorithmic selection rather than hardware complexity
Data Source
AI summary
Provided is random access method, performed by terminal for uplink data transmission during random access process between cellular based machine communication terminal and base station. The method includes performing random access process between cellular based machine communication terminal and base station, and the random access process includes selecting random access resource by considering coverage level and whether to support multi-tone transmission or not. Terminal can perform efficient random access process in response to coverage level, subcarrier spacing configuration, multi-tone configuration when machine communication terminal or machine communication device which operates in cellular based IoT system perform random access, number of repetition may be increased, when coverage level is changed, by minimizing the change in coverage level, and operation time of the terminal, due to standing by up to PRACH resource corresponding to the coverage level, may be reduced to reduce energy consumption and to enhance delay time performance.