RACH-less Timing Advance Determination for Wireless Handover
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Solution Overview
Problem
Current wireless communication systems face challenges in determining timing advance values during handovers without using the random access channel (RACH) procedure, leading to increased latency and mobility interruptions.
Innovation Solution
The method involves determining a target base station timing advance value based on the timing offset, timing difference between base stations, and source base station timing advance value, without performing a RACH procedure, by using information such as reference signal timing differences and uplink reference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RACH procedure is used for timing advance determination during handover, then timing advance can be accurately obtained, but handover latency increases and mobility interruption worsens
Solution Approach 1:
The source base station performs preliminary calculations of the target timing advance value using the existing timing advance from the source base station and the timing difference between source and target base stations. This preliminary action allows the UE to obtain the target timing advance without needing to perform the RACH procedure, thereby reducing handover latency while maintaining timing accuracy.
Solution Approach 2:
The patent introduces an intermediary calculation method where the target timing advance is derived through mathematical relationships involving the source timing advance, timing difference between base stations, and timing offset. This intermediary approach replaces the direct RACH procedure with a computational method that achieves the same timing advance determination without the latency overhead.
2Measurement precision
If RACH procedure is used for timing advance determination, then timing advance can be determined, but communication efficiency decreases and mobility interruption increases
Solution Approach 1:
The source base station calculates the target timing advance value in advance using the timing advance from the source base station and the timing difference information. This preliminary computation eliminates the need for the UE to perform RACH procedures at the target base station, significantly improving communication efficiency during handover while maintaining accurate timing advance determination.
Solution Approach 2:
The patent extracts the essential function of timing advance determination from the RACH procedure and implements it through a direct calculation method. By taking out the timing advance determination function from the RACH process, the system achieves the same measurement precision without the procedural overhead that reduces communication efficiency.
3Measurement precision
If RACH procedure is used for handover, then timing advance can be obtained, but handover completion time increases
Solution Approach 1:
The source base station performs preliminary calculation of the target timing advance value before the handover execution. This preliminary action uses the source timing advance and timing difference information to compute the target timing advance, allowing the handover to complete much faster without requiring the UE to perform RACH procedures at the target base station.
Solution Approach 2:
The patent enables the handover process to skip the RACH procedure step by directly calculating the target timing advance value. This skipping of the RACH procedure (which would otherwise be required) rushes through the handover process, significantly reducing handover duration while still obtaining the necessary timing advance value for successful handover completion.
Data Source
AI summary
This disclosure provides systems, methods and apparatus for determining a target base station timing advance value between a user equipment (UE) and target base station in connection with a random access channel (RACH)-less handover procedure. In one aspect, the UE may determine the target base station's timing advance based at least in part on a timing difference between the target base station and the source base station and based at least in part on a timing offset associated with an uplink and a downlink of the UE. In some aspects, the target base station may determine the timing advance using an uplink reference signal of the UE. In some aspects, the UE may report a timing difference between the target base station and the source base station, and the source cell may determine a timing advance based at least in part on the timing difference.