Random Access Timing in Non-Terrestrial Networks
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Solution Overview
Problem
In non-terrestrial wireless communication networks, the long round trip time and large timing advance values lead to delays in random access procedures due to the long propagation delays and Doppler effects, especially in low earth orbit and geostationary earth orbit scenarios, causing issues with timing alignment and data transmission.
Innovation Solution
The implementation of procedures that determine optimal transmission timings for random access in non-terrestrial networks by applying configured slot offsets to adjust for round trip times, allowing for early initiation of random access and adaptive monitoring of PDCCH, and utilizing GNSS for timing and frequency adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional random access procedures are used in non-terrestrial networks, then the basic communication protocol is maintained, but scheduling latency and data transmission delays increase due to long round trip times and large timing advance values
Solution Approach 1:
The network equipment determines and signals slot offsets to the UE before the random access procedure begins. These slot offsets are configured in advance to adjust for the specific round trip time characteristics of non-terrestrial networks, allowing the UE to proactively align its transmission timings without experiencing delays during the actual random access execution.
Solution Approach 2:
The invention introduces configurable slot offsets as a new parameter that modifies the timing characteristics of random access transmissions. By adjusting these slot offsets based on the round trip time of the non-terrestrial network, the system changes the temporal parameters of message transmission to optimize performance for satellite-based networks with inherently longer propagation delays.
2Reliability
If timing advance values are increased to accommodate non-terrestrial network propagation delays, then coverage is improved, but timing alignment accuracy deteriorates due to Doppler effects and long round trip times
Solution Approach 1:
The network equipment determines slot offsets specifically tailored to each UE's conditions in the non-terrestrial network, considering local factors such as the UE's velocity, position, and the specific satellite's orbital characteristics. This localized approach allows each UE to have optimized timing parameters that account for its specific Doppler shift and propagation delay conditions, improving timing alignment accuracy for each individual connection.
Solution Approach 2:
The system uses feedback from the random access response and subsequent uplink transmissions to refine and adjust the slot offsets. The network equipment monitors the timing of received messages and can update the slot offset configurations to compensate for Doppler effects and maintain accurate timing alignment as the satellite and UE move relative to each other.
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for random access procedure in a non-terrestrial network. One apparatus (500) includes a processor (505) that determines one or more transmission timings associated with a random access procedure, each transmission timing determined based on each transmission slot and a timing advance value for transmitting messages between the UE and a mobile wireless communication network, the mobile wireless communication network comprising a non-terrestrial network (“NTN”), each transmission slot determined by applying a configured slot offset, the configured slot offset applied to adjust for a round trip time within the NTN. An apparatus (500) includes a transceiver (525) that transmits one or more messages during the random access procedure based on the determined one or more transmission timings.