NTN Uplink Synchronization Using RRC Gaps for IoT Devices
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Solution Overview
Problem
Existing IoT devices in Non-Terrestrial Networks (NTN) face inefficiencies in uplink synchronization, particularly for long data transmissions, leading to redundant procedures, increased resource usage, and power consumption due to the need for re-acquiring GNSS position fixes and satellite ephemeris data.
Innovation Solution
Implementing a gap configuration within the RRC connected state to allow IoT devices to receive system broadcasted information for timing and frequency compensation, enabling UL synchronization through contention-free random access, thereby reducing the need for frequent state transitions and conserving resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If IoT devices transition to RRC idle state for data transmission, then power consumption is reduced, but uplink synchronization performance deteriorates due to redundant state transitions and GNSS re-acquisitions
Solution Approach 1:
The system pre-configures gap patterns and pre-synchronizes uplink timing before data transmission begins. The network device provides gap configuration information indicating time gaps for potential uplink transmissions, and the UE performs uplink synchronization in advance during RRC connected state, avoiding the need for re-synchronization during idle state transitions.
Solution Approach 2:
The system dynamically switches between RRC connected and idle states based on data transmission requirements. During gap periods when uplink transmission is needed, the device transitions to RRC connected state to perform synchronization and transmission, then returns to idle state for power saving. This dynamic state management optimizes both power consumption and synchronization performance.
2Adaptability or versatility
If IoT devices perform frequent state transitions between RRC connected and idle, then adaptability to transmission requirements is improved, but device complexity and resource usage increase
Solution Approach 1:
The network device pre-configures gap patterns and provides gap configuration information to the UE before data transmission begins. This preliminary configuration includes time gap patterns, uplink timing advance values, and other synchronization parameters, reducing the need for complex real-time state management and frequent re-synchronization procedures.
3Reliability
If IoT devices maintain RRC connected state for long data transmissions, then uplink synchronization is improved, but power consumption increases
Solution Approach 1:
The system uses periodic gap patterns where the UE transitions to RRC connected state at predetermined intervals to perform uplink transmission and synchronization, then returns to idle state. The gap configuration information specifies these periodic time gaps, allowing the device to maintain synchronization periodically while maximizing power saving during idle periods.
Data Source
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AI summary
Embodiments of the present disclosure relate to devices, methods, apparatuses, and computer readable storage media of enhanced ULsynchronization for improved system performance. The method comprises obtaining a configuration of a gap within which a radio resource control connected state of the first device is kept; receiving, within the gap, system broadcasted information used for deriving a compensation associated with a transmission between the first device and a second device; and performing a uplink synchronization between the first device to the second device within the gap. In this way, a process of the GNSS fix position refreshing and /or satellite ephemeris data reception and UL/DL re-synchronization can be achieved by the UE in RRC connected mode and therefore the resources and power consumption can be reduced.