Relay Uplink Timing Advance for Multi-Leg NTN Paths
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Solution Overview
Problem
In non-terrestrial networks with relay entities, determining transmission delays for communication paths involving multiple legs is complex due to increased signaling overhead and uncertainty about the location of the base station, making it difficult to calculate an appropriate timing advance for uplink transmissions.
Innovation Solution
A hybrid approach is implemented where the user equipment autonomously calculates the service link delay and the network entity controls the feeder link delay through signaling, adjusting uplink transmission timing using a combined timing advance formula (NTA+NTA,offset,feeder)×Tc, with NTA calculated by the UE based on satellite position and NTA,offset,feeder controlled by the gNB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a round trip delay is computed to determine transmission delay for uplink timing alignment, then timing advance can be calculated, but in multi-leg relay paths the computation becomes complicated and signaling overhead increases significantly
Solution Approach 1:
The patent segments the total transmission delay into two distinct components: service link delay (between UE and relay) and feeder link delay (between relay and base station). The UE autonomously determines the service link delay based on its own location and the relay's location, while the network provides the feeder link delay through signaling. This segmentation allows each component to be determined using appropriate methods for that specific link, reducing overall complexity.
Solution Approach 2:
The UE autonomously determines its own service link delay based on its known location and the relay's location, without requiring network assistance for this specific measurement. This self-service approach eliminates the need for complex network-coordinated measurements for the service link portion, reducing signaling overhead while maintaining measurement precision.
2Device complexity
If autonomous determination of delay by UE is used based on location knowledge, then signaling overhead is reduced, but the UE may not always know the location of the base station
Solution Approach 1:
The patent divides the delay determination into two segments: service link delay (which the UE can determine autonomously using its location and the relay's location) and feeder link delay (which the network provides through signaling). This segmentation allows the UE to use autonomous determination where possible while relying on network-provided information only for the feeder link portion, minimizing information loss while reducing signaling overhead.
Solution Approach 2:
The relay entity acts as an intermediary that the UE can use for autonomous location-based delay calculation. Since the UE knows its own location and can obtain the relay's location, it can calculate the service link delay autonomously. The relay thus serves as a known reference point that enables autonomous determination without requiring direct UE-base station location knowledge.
3Adaptability or versatility
If multiple legs are involved in the communication path, then relay functionality is enabled, but the number of communication portions that need to be aggregated increases
Solution Approach 1:
The patent segments the multi-leg communication path into distinct service link and feeder link portions, each with its own delay component. Instead of treating the entire multi-leg path as a single complex aggregation problem, the solution separates the delays into manageable components that can be determined independently and then combined, reducing the complexity of delay aggregation while maintaining relay functionality.
Data Source
AI summary
A method and apparatus are provided, in which a service link path delay relative to a first leg of a communication path of a communication between the user equipment and a network entity via a relay entity is estimated (602), where the first leg corresponds to a portion of the communication path between the user equipment and the relay entity. A feeder link path delay relative to a second leg of the communication path is determined (604), where the second leg corresponds to a portion of the communication path between the relay entity and the network entity, based upon at least a received signaling indication. A timing advance value is calculated (606), based upon the service link path delay and the feeder link path delay. An uplink transmission timing of the user equipment is adjusted (608), based upon the calculated timing advance value.