Random Access Type Selection in NTN Using RTT, TA, and RSRP
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Solution Overview
Problem
In non-terrestrial networks (NTN), selecting the appropriate random access type (2-step or 4-step) based on reference signal receiving power (RSRP) measurement is inaccurate, leading to improper type selection and increased delay due to under/over measurement errors, especially at cell edges and centers.
Innovation Solution
Selecting the random access type based on round trip time (RTT), timing advance (TA), and RSRP measurements, with network device broadcasting configuration information including RTT/TA thresholds and resource configurations for accurate type selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RSRP measurement is used for random access type selection, then the selection process is simple, but the measurement precision is insufficient leading to inaccurate type selection
Solution Approach 1:
The patent changes the measurement parameter from RSRP (power-based) to RTT and TA (time-based parameters). This parameter substitution resolves the contradiction by providing more accurate measurement for random access type selection, especially in NTN scenarios where RSRP measurements are unreliable due to large propagation delays and path loss variations.
Solution Approach 2:
The patent introduces RTT and TA as intermediary parameters that better reflect the actual channel conditions and propagation characteristics. These intermediary measurements serve as more reliable indicators for random access type selection compared to direct RSRP measurements, particularly in non-terrestrial networks.
2Ease of manufacture
If RSRP-based type selection is used, then the implementation is straightforward, but the reliability of type selection deteriorates at cell edges and centers
Solution Approach 1:
The patent substitutes the RSRP parameter with RTT and TA parameters that are more reliable for type selection. Time-based measurements are less susceptible to the path loss variations and shadowing effects that cause RSRP measurement failures at cell edges and centers, thereby improving reliability while maintaining implementation feasibility.
Solution Approach 2:
The patent implements a feedback mechanism where the network device provides configuration information including thresholds for RTT and TA. The terminal device uses these thresholds to make informed decisions about random access type selection, improving reliability through network-guided parameter adjustment rather than relying solely on local RSRP measurements.
3Device complexity
If inaccurate type selection occurs, then the system complexity remains low, but the delay increases due to under/over measurement errors
Solution Approach 1:
The patent changes from power-based measurement (RSRP) to time-based measurement (RTT, TA) to reduce measurement errors. This parameter substitution reduces under/over measurement errors that cause inappropriate random access type selection, thereby reducing access delay without significantly increasing system complexity since the measurement mechanisms are already available in the system.
Data Source
AI summary
A method and apparatus for random access type selection are provided. A terminal device selects a random access type according to target information, where the target information includes at least one of a round trip time (RTT) of signal propagation between the terminal device and a network device, a timing advance (TA) estimated by the terminal device, or a reference signal received power (RSRP) measured by the terminal device.