Uplink Time Alignment Control for 5G Handover Delay Reduction
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Solution Overview
Problem
Current 5G communication systems face challenges in minimizing delay during neighboring cell measurement and handover, particularly in beam-based communication systems, where uplink time alignment is not effectively managed, leading to interference and decoding errors.
Innovation Solution
A method and apparatus that involve a terminal transmitting a random access preamble, receiving timing advance information, starting a time alignment timer, requesting system information, receiving a response message, transmitting a HARQ acknowledgment, and stopping the timer, allowing for efficient uplink time alignment and reducing measurement delays during handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal continuously maintains uplink time alignment through random access procedures, then uplink signal orthogonality is maintained, but handover delay and measurement delay increase
Solution Approach 1:
The terminal performs random access procedure and acquires timing advance information in advance before handover is actually needed. The time alignment timer is started preliminarily to ensure uplink time alignment is ready before handover execution, thus reducing actual handover delay while maintaining signal orthogonality.
Solution Approach 2:
The system dynamically adjusts the time alignment timer management based on terminal state and handover requirements. The timer is started or restarted when specific conditions are met (e.g., when receiving random access response), and stopped when handover is complete, creating a flexible time alignment maintenance mechanism that balances reliability and delay.
2Reliability
If the terminal performs frequent random access to maintain time alignment, then uplink synchronization is improved, but system resource consumption and interference increase
Solution Approach 1:
The terminal uses feedback from the network (timing advance commands in random access response) to adjust its uplink transmission timing. The time alignment timer provides feedback mechanism to track alignment validity, allowing the terminal to maintain synchronization only when necessary, thereby reducing unnecessary random access attempts and associated interference.
Solution Approach 2:
The terminal autonomously manages its own uplink time alignment by monitoring the time alignment timer and performing random access only when the timer expires or alignment is needed. This self-service approach reduces network resource consumption and minimizes interference caused by frequent coordinated random access procedures.
Data Source
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AI summary
A communication technique for convergence of internet of things (IoT) technology, a fifth-generation (5G) communication system for supporting a higher data transfer rate beyond a fourth-generation (4G) system, and a system therefor are provided. The disclosure can be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart or connected cars, health care, digital education, retail business, and services associated with security and safety) based on 5G communication technology and IoT-related technology. An embodiment relates to a method for controlling an uplink time alignment during execution of random access by a base station operating a broadband.