Communications Device Handover Using Frame Timing Difference
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Solution Overview
Problem
Future wireless communications networks face challenges in efficiently supporting a diverse range of devices with varying data traffic profiles, including reduced complexity devices and high latency tolerance, and existing handover procedures in LTE and NR systems incur delays and resource wastage due to synchronization requirements.
Innovation Solution
A RACH-less handover method is introduced, where the user equipment determines the uplink propagation delay and timing advance of the target cell by measuring the frame timing difference between the serving and target cells, eliminating the need for PRACH transmissions and DL responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedures with synchronization requirements are used, then timing alignment is achieved, but handover latency increases and resources are wasted
Solution Approach 1:
The UE calculates the timing advance for the target cell in advance during the handover procedure, before actual uplink transmission to the target cell is required. This preliminary calculation uses the measured frame timing difference between serving and target cells, allowing the UE to be pre-synchronized with the target cell and avoid latency during the handover execution phase
Solution Approach 2:
The patent extracts and eliminates the random access procedure (PRACH transmissions and DL responses) from the handover process. By removing this synchronization step, the handover latency is significantly reduced while the UE still achieves proper timing alignment through the calculated timing advance value
2Reliability
If RACH procedures are performed during handover, then synchronization is achieved, but resource wastage occurs
Solution Approach 1:
The random access procedure including PRACH transmissions and downlink responses is completely removed from the handover process. The UE achieves synchronization directly through timing advance calculation based on frame timing measurements, eliminating the need for dedicated random access resources and reducing overall system resource consumption
Solution Approach 2:
The UE performs self-synchronization by autonomously calculating its timing advance for the target cell using the measured frame timing difference. This self-service approach eliminates the need for network-coordinated synchronization procedures, reducing both resource wastage and handover latency
Data Source
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AI summary
A communications device is provided. The communications device comprises transceiver circuitry configured to transmit signals to and/or to receive signals from a first cell of a wireless communications network, and controller circuitry. The controller circuitry is configured in combination with the transceiver circuitry to determine that the communications device is to perform a handover procedure from the first cell to a second cell of the wireless communications network, to measure a difference between the start of a first radio frame received from the first cell and the start of a second radio frame received from the second cell, and to determine, during the handover procedure, in accordance with the measured difference, at least one of a value of a propagation delay of the second cell and a value of a timing advance of the second cell, the propagation delay of the second cell defining a time taken for a signal to travel one way between the communications device and the second cell, the timing advance of the second cell being defining a time taken for a signal to travel a round trip between the communications device and the second cell.