Destination Time Alignment Calculation for Non-Co-located Cell Handovers
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Solution Overview
Problem
Current time alignment solutions in radio access networks are limited to co-located cell configurations, requiring the use of shortened bursts during handovers, which leads to interruptions and inefficiencies, especially when serving cells and target cells are not co-located.
Innovation Solution
A method and arrangement for calculating a destination time alignment value (TA2) by determining the time differences between reference signal transmissions and receptions in both the source and destination cells, allowing for seamless handovers without shortened bursts, even in non-co-located scenarios, using the formula TA2=C-A, where A and C represent specific time differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shortened bursts are used during handover, then timing alignment can be maintained, but connection interruption increases
Solution Approach 1:
The network calculates and provides the destination time alignment value (TA2) to the user equipment before the handover is executed. This preliminary calculation uses the formula TA2=C-A, where A is the time difference between destination reference signal transmission and reception, and C is the time difference between destination reference signal reception and user equipment transmission. By having TA2 ready in advance, the user equipment can immediately use normal bursts without interruption when handover occurs.
2Productivity
If normal bursts are used during handover, then connection continuity is maintained, but timing alignment accuracy deteriorates in non-co-located cells
Solution Approach 1:
The network acts as an intermediary by calculating the destination time alignment value (TA2) using the formula TA2=C-A, where A represents the time difference between destination reference signal transmission and reception, and C represents the time difference between destination reference signal reception and user equipment transmission. This intermediary calculation provides accurate timing alignment information to the user equipment, enabling the use of normal bursts during handover even in non-co-located cell scenarios where direct measurement would be inaccurate.
3Device complexity
If co-located cell assumption is made, then timing alignment is simplified, but applicability to general cell configurations is reduced
Solution Approach 1:
The invention changes the approach from assuming co-located cells (where source and destination base stations are at the same location) to calculating timing alignment based on actual time differences A and C that account for different base station locations. The formula TA2=C-A dynamically adapts to any cell configuration by using measured time differences rather than assuming a fixed co-located relationship, thus maintaining simplicity while increasing versatility.
Data Source
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AI summary
The invention relates to a method and arrangement for managing a calculation of a destination time alignment value TA2 to be used by a user equipment in a destination cell after a handover in a radio access network. The radio access network comprises a source cell, the destination cell and a user equipment which is adapted to switch to communicate with a destination base station comprised in the destination cell after the handover. The source cell is adapted to transmit a first reference signal and the destination cell is adapted to transmit a second reference signal. The method comprises the step of obtaining a first information comprising the time difference A between a point of time when the second reference signal is transmitted and a point of time when the destination cell receives the user equipment transmission, obtaining a second information comprising the time difference C between the point of time when second reference signal is received and a point of time when the user equipment transmission is transmitted, and calculating the destination time alignment TA2, by means of the formula [TA2=C-A].