Grant-Free Uplink Synchronization via Timing Advance Options
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Solution Overview
Problem
Current 4G LTE cellular networks require UEs to perform a RACH preamble procedure for initial uplink data transmissions, which adds latency and overhead, making it inefficient for grant-free uplink data transmissions.
Innovation Solution
The system allows initial grant-free uplink data transmissions to be performed directly without updating timing advance parameters, using cyclic prefix durations that compensate for propagation delays and omitting timing advance reference signaling, enabling synchronization without additional overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UEs perform RACH preamble procedure for initial uplink data transmissions, then timing advance parameters can be determined, but latency and overhead increase
Solution Approach 1:
The base station pre-calculates and provides timing advance parameter options to UEs before actual data transmission. The UE selects from pre-prepared options based on its measured distance or signal strength, eliminating the need to wait for RACH preamble exchange and immediately performing synchronized uplink transmission.
Solution Approach 2:
The timing advance parameter selection is divided into discrete options (first TA option, second TA option) corresponding to different distance ranges or signal strength thresholds. The UE segments the parameter selection process by measuring its position relative to the base station and choosing the appropriate pre-calculated TA option, avoiding iterative RACH procedures.
2Stability of the object's composition
If UEs perform RACH preamble procedure for initial uplink data transmissions, then uplink synchronization can be achieved, but signaling overhead increases
Solution Approach 1:
The invention extracts the timing advance parameter determination function from the RACH preamble procedure. Instead of using RACH preambles to negotiate TA parameters, the base station directly provides pre-calculated TA options to the UE, removing the unnecessary RACH signaling overhead while maintaining synchronization capability.
Solution Approach 2:
The UE autonomously determines which TA option to use by measuring its own distance or signal strength relative to the base station. This self-service approach eliminates the need for interactive RACH preamble exchange, where the base station would need to process and respond to UE preambles to determine appropriate timing advance values.
3Stability of the object's composition
If timing advance parameters are updated through reference signaling, then uplink synchronization is maintained, but transmission efficiency decreases for grant-free operations
Solution Approach 1:
Timing advance parameter options are pre-calculated and provided to the UE before grant-free data transmission begins. The UE selects from these pre-prepared options based on real-time measurements, enabling immediate synchronized transmission without waiting for reference signaling exchanges during the actual data transmission process.
Data Source
AI summary
A method and apparatus for timing advance (TA) synchronization for uplink (UL) data transmissions are provided. A base station transmits a TA instruction to a UE. The TA instruction indicates one of at least two TA options. The first TA option indicates direct initial grant-free (GF) uplink (UL) data transmissions. The second TA option indicates indirect initial GF UL data transmissions with the UE initiating TA reference signaling for updating a TA parameter of the UE. The UE performs an initial GF UL data transmission to the base station based on the TA instruction.