NTN Random Access Offset Scheme for PRACH Repetition Selection
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Solution Overview
Problem
In Non-Terrestrial Network (NTN) communication, the large Round Trip Time (RTT) leads to significant transmission latency during the random access process, and determining Enhanced Coverage Level (CEL) based solely on Reference Signal Received Power (RSRP) can result in inaccurate selection of Physical Random Access Channel (PRACH) repetitions, affecting the success probability of random access.
Innovation Solution
Introduce a first offset parameter to improve the accuracy of determining the number of PRACH repetitions by considering factors such as base station height, altitude, coverage, and transmission latency, which compensates for RSRP measurement deviations in NTN scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PRACH repetitions are transmitted to improve random access success probability, then reliability is improved, but transmission latency increases due to large RTT in NTN
Solution Approach 1:
The patent changes the parameter used for determining PRACH repetition number from RSRP alone to a composite parameter that includes RSRP and an offset value. This offset is configured by the network and accounts for NTN-specific conditions such as large RTT and coverage characteristics, allowing the system to optimize the number of repetitions to balance reliability and latency.
2Device complexity
If CEL is determined based solely on RSRP threshold to simplify the process, then device complexity is reduced, but measurement precision deteriorates in NTN scenarios
Solution Approach 1:
The patent introduces an offset value as an intermediary element between the RSRP measurement and the CEL determination. This offset acts as a correction factor that compensates for NTN-specific measurement deviations without requiring complex alternative measurement methods, thus maintaining simplicity while improving accuracy.
3Reliability
If the number of PRACH repetitions is increased to cover NTN latency, then reliability is improved, but the accuracy of repetition selection deteriorates when using RSRP-only thresholds
Solution Approach 1:
The patent modifies the parameter for PRACH repetition selection by adding an offset to the RSRP value. This creates a new effective threshold that better reflects actual signal conditions in NTN, enabling more accurate selection of the appropriate number of repetitions without relying on overly conservative RSRP-only thresholds.
Data Source
AI summary
The disclosure provides method and device in communication node for wireless communication. The communication node receives a first signaling and a first signal, and transmits a second signal; wherein the first signaling is used for determining a first offset; the first signal is used for determining a first measurement result; the second signal includes N second sub-signal(s), a first sequence is used for determining the N second sub-signal(s). In view of the problems that the method to determine repetitions of a preamble sequence is not applicable to a large-latency network and that multiple attempts of random access in a large-latency network will cause a larger latency, the disclosure provides an offset based scheme, in which the communication node introduces the first offset when determining the repetitions of a preamble sequence, thereby selecting an more appropriate number of repetitions, improving the successful probability of random access and reducing latency.