PRACH Sequence Detection in NTN Handover Latency Reduction
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Solution Overview
Problem
In new radio (NR) and non-terrestrial networks (NTN) systems, the handover procedure for user equipment (UE) switching from a source cell to a target cell requires a random-access channel (RACH) procedure, which increases handover latency due to limited service coverage and restricted transmit power of commercial handheld devices like smartphones.
Innovation Solution
A resource accessing method that involves detecting and transmitting a physical random-access channel (PRACH) sequence over multiple radio opportunities (ROs) within a RO group, enhancing PRACH transmission coverage and reducing latency by combining ROs for improved detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a RACH procedure is performed for handover in NR and NTN systems, then the UE can switch from source cell to target cell, but the handover latency increases due to limited service coverage and restricted transmit power
Solution Approach 1:
The patent combines multiple ROs into a RO group for PRACH transmission. Instead of using a single RO, the UE transmits the same PRACH sequence across multiple ROs within a group, and the network device detects the sequence by combining signals from multiple ROs. This merging approach increases detection probability and extends coverage without requiring additional time for separate transmission attempts, thereby reducing handover latency while maintaining reliability.
2Area of stationary object
If multiple ROs are used for PRACH transmission, then the transmission coverage is enhanced, but the device complexity increases
Solution Approach 1:
The patent makes the RO group a universal resource structure that can be configured and used across different cells and scenarios. The same RO group configuration can be applied universally for handover and other random access scenarios. The UE simply needs to know the RO group configuration to transmit across multiple ROs, and the network device uses the same configuration for detection, simplifying implementation while extending coverage.
3Measurement precision
If PRACH sequence is transmitted across multiple ROs, then the detection performance is improved, but the use of energy increases
Solution Approach 1:
The network device combines PRACH signals detected from multiple ROs within an RO group to improve detection performance. By merging the detection results from multiple ROs, the system achieves better signal detection probability and accuracy without requiring the UE to transmit at higher power levels continuously. This combining approach allows for more energy-efficient transmission while maintaining or improving detection performance.
Data Source
AI summary
A resource accessing method is provided. In the method, one physical random-access channel (PRACH) sequence is detected at a random-access channel occasion (RACH occasion, RO) group. The RO group includes a plurality of ROs, wherein the ROs are resources used for a physical random-access channel (PRACH) transmission with a same PRACH sequence.