Random Access Preamble Timing Partition for Large Propagation Delay
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Solution Overview
Problem
In wireless communication systems, large propagation delays between user equipment (UE) devices and base stations can cause a mismatch in Random-Access Radio Network Temporary Identifiers (RA-RNTIs), leading to failed random access procedures, especially in networks with extended cell sizes or non-terrestrial networks where propagation delays are significantly greater than traditional systems.
Innovation Solution
The UE devices and base stations employ a method to account for propagation delays by using a common delay and differential delay to synchronize transmission and reception timing, allowing UE devices to select a random access preamble from a partitioned set based on configured correspondence between time slots and subsets, ensuring accurate RA-RNTI computation and successful random access even in large propagation delay scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the propagation delay between UE device and base station is large, then the coverage area can be extended, but the random access procedure fails due to RA-RNTI mismatch
Solution Approach 1:
The patent segments the random access procedure into distinct phases with separate RA-RNTI computations. The UE computes RA-RNTI based on transmission slot while the base station computes it based on reception slot, allowing them to differ. This segmentation resolves the contradiction by accepting different RA-RNTI values for different purposes (monitoring vs. response transmission) rather than requiring them to match.
Solution Approach 2:
The patent changes the parameters used for RA-RNTI computation in different contexts. The UE uses transmission slot index while the base station uses reception slot index, effectively changing the time reference parameter. This allows the system to handle large propagation delays by accepting that the same RA-RNTI formula will yield different values when applied at different time points in the propagation chain.
2Loss of time
If the propagation delay is larger than slot duration, then the time synchronization between UE and base station becomes difficult, but random access procedure requires accurate timing
Solution Approach 1:
The patent applies preliminary timing advance compensation before the random access procedure begins. The base station provides a common delay value that the UE uses to pre-adjust its transmission timing. This preliminary action reduces the effective propagation delay impact on slot indexing, making the timing relationship more predictable and reducing the mismatch between UE and base station time references.
3Adaptability or versatility
If different time slot indices are used by UE and base station, then the RA-RNTI computation diverges, but the random access response cannot be delivered
Solution Approach 1:
The patent introduces the common delay value as an intermediary parameter that mediates between UE transmission timing and base station reception timing. The base station uses this common delay to determine the correspondence between received preambles and transmission time slots, even when the raw slot indices differ. This intermediary allows the system to bridge the timing gap caused by propagation delay while maintaining accurate RA-RNTI association for response delivery.
Data Source
AI summary
A user equipment (UE) device may perform random access to a base station in the context where propagation delay between the base station and the UE device is large. The UE device randomly selects a random access preamble from an available set of preambles. The UE device selects a time slot for transmission of the random access preamble based on a configured correspondence between allowable time slots and subsets of the available set. The UE device transmits the random access preamble to a base station in the selected time slot, with timing advance to compensate for a common delay. Thus, the base station, knowing the configured correspondence, is able to determine the time slot in which the random access preamble was transmitted. The UE device receives a random access response that has been addressed with a Random Access Radio Network Temporary Identifier (RA-RNTI).