User Terminal Omitting Random Access Preamble During Handover
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Solution Overview
Problem
In mobile communication systems, interference occurs during handover procedures due to the transmission of random access preamble signals, which existing technologies fail to effectively prevent.
Innovation Solution
A user terminal and base station system that determines whether to omit the transmission of random access preamble signals during handover, using information on radio resource assignment and timing adjustments to prevent interference, allowing for seamless handover without signal sequence depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user terminal transmits a random access preamble signal during handover procedure, then the target base station can generate timing information for adjusting uplink transmission timing, but interference occurs because the user terminal transmits the random access preamble signal around the radio resource used for transmitting the random access preamble signal
Solution Approach 1:
The patent extracts the timing adjustment function from the random access preamble signal transmission process. The target base station generates timing information based on the received random access preamble signal, but the user terminal omits transmitting the random access preamble signal in subsequent uplink transmissions. This separation allows timing adjustment to be achieved without the harmful interference caused by continuous random access preamble signal transmission.
Solution Approach 2:
The timing information is generated in advance by the target base station based on the initial random access preamble signal reception. This preliminary timing adjustment is performed before the user terminal begins normal uplink communication, preventing interference during the main communication phase while still achieving accurate timing synchronization.
2Productivity
If the user terminal transmits the random access preamble signal during handover, then the handover procedure can be initiated, but the transmission causes interference that degrades communication quality
Solution Approach 1:
The patent allows the handover procedure to proceed quickly by having the user terminal omit the random access preamble signal transmission after the initial timing adjustment. The system skips the repetitive random access preamble signal transmissions that would otherwise be necessary for maintaining synchronization, rushing through the handover process efficiently while avoiding continuous interference.
3Object-generated harmful factors
If the user terminal omits the transmission of the random access preamble signal, then interference is prevented, but timing information for adjusting uplink transmission timing must be obtained through alternative means
Solution Approach 1:
The target base station acts as an intermediary that receives the initial random access preamble signal, generates timing information, and provides it to the user terminal. This intermediary mechanism allows the user terminal to obtain timing adjustment information without continuously transmitting random access preamble signals, reducing interference while maintaining timing synchronization through the base station's mediation.
Data Source
AI summary
A system, user terminal, and processor determine whether to omit transmission of a random access preamble signal in a handover procedure from the first cell controlled by a first base station to a second cell controlled by a second base station when the user terminal transmits a notification indicating that a connection with the second cell is completed. The second base station notifies the user terminal of information via the first base station in response to admitting a handover request, the information indicating first information for adjusting a transmission timing of the notification and second information on a radio resource for transmitting the notification to the second base station. The user terminal determines that it omits transmission of the random access preamble signal on a basis of the first information, and transmits notification to the second base station by use of the second information in response to the determination.