NTN Random Access Selection for Intra- and Inter-Satellite Handover

Solution Overview

Problem

In non-terrestrial networks (NTN) using Low Earth Orbit (LEO) satellites, the frequent need for Random Access (RA) procedures due to handovers or cell switching leads to significant performance overhead, particularly in RRC Connected and RRC Idle/Inactive client devices, as satellites move relative to Earth at 7.5 km/s, necessitating efficient RA procedure selection.

Innovation Solution

Client devices and network node devices employ a method to identify whether the needed RA is intra-satellite or inter-satellite, performing a first RA procedure with a single message for intra-satellite access and a second RA procedure with separate messages for inter-satellite access, based on explicit or implicit signaling, to optimize resource usage and latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single random access procedure is used for all satellite handovers, then the procedure simplicity is maintained, but the signaling overhead increases and performance deteriorates

Engineering Contradiction:

ImproveRA procedure simplicityVSAvoidsignaling overhead

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent segments the random access procedure into two distinct types: Type-1 RA procedure for intra-satellite handovers and Type-2 RA procedure for inter-satellite handovers. This segmentation allows each procedure to be optimized for its specific scenario, reducing unnecessary signaling overhead while maintaining simplicity for the most common case.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic selection capability where the client device determines which RA procedure type to use based on the handover scenario (intra-satellite vs. inter-satellite). This dynamic adaptation allows the system to optimize performance for each specific situation rather than using a fixed procedure for all cases.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If a single random access procedure is used for all satellite handovers, then the implementation simplicity is maintained, but the RA performance and latency improve

Engineering Contradiction:

Improveimplementation simplicityVSAvoidRA latency

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent segments the random access procedure into two distinct types: Type-1 RA procedure for intra-satellite handovers and Type-2 RA procedure for inter-satellite handovers. This segmentation allows each procedure to be optimized for its specific scenario, reducing unnecessary signaling overhead while maintaining simplicity for the most common case.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic selection capability where the client device determines which RA procedure type to use based on the handover scenario (intra-satellite vs. inter-satellite). This dynamic adaptation allows the system to optimize performance for each specific situation rather than using a fixed procedure for all cases.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If the client device performs frequent RA procedures due to satellite movement, then the network adapts to mobility, but the overhead and performance impact increase

Engineering Contradiction:

Improvenetwork mobility adaptationVSAvoidRA procedure overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent segments the random access procedure into two distinct types: Type-1 RA procedure for intra-satellite handovers and Type-2 RA procedure for inter-satellite handovers. This segmentation allows each procedure to be optimized for its specific scenario, reducing unnecessary signaling overhead while maintaining simplicity for the most common case.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic selection capability where the client device determines which RA procedure type to use based on the handover scenario (intra-satellite vs. inter-satellite). This dynamic adaptation allows the system to optimize performance for each specific situation rather than using a fixed procedure for all cases.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12438600B2Random access procedure selection

Publication Date: 2025.10.07 NOKIA TECHNOLOGIES OY

AI summary

According to an example embodiment, a client device comprises at least one processor; and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the client device to: detect need for random access, random access, in a non-terrestrial network to a target cell of the non-terrestrial network; identify whether the needed random access is intra-satellite or inter-satellite; in response to the needed random access being intra-satellite, perform a first random access procedure, wherein, in the first random access procedure, the client device transmits a random access preamble and a payload data in a single message; and in response to the needed random access being inter-satellite, perform a second random access procedure wherein, in the second random access procedure, the client device transmits a random access preamble and a payload data in separate messages. A client device, a network node device, methods and computer program products are disclosed.