Preemptive Random Access Preambles for Fast Terminal Synchronization
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Solution Overview
Problem
Existing wireless communication systems face challenges in reducing preamble collisions during initial access, particularly in scenarios with a large number of terminals, leading to increased retransmissions and reduced synchronization efficiency, especially in applications requiring high absolute time synchronization like factory automation.
Innovation Solution
The method involves terminals requesting and being allocated preemptive preambles by the base station, allowing exclusive use of these preambles for a predetermined period, thereby reducing contention and enabling quick synchronization and access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If terminals use random preambles for initial access, then the access procedure is simple and fast, but preamble collisions increase when many terminals access simultaneously
Solution Approach 1:
The base station performs preliminary allocation of dedicated preambles to terminals before the actual random access occurs. This preliminary action allows terminals to use pre-configured preambles during the random access procedure, significantly reducing collision probability while maintaining fast access speeds. The base station maintains a pool of dedicated preambles and allocates them to terminals that request initial access.
Solution Approach 2:
The preamble pool is segmented into two distinct parts: dedicated preambles allocated by the base station and random preambles selected by terminals. This segmentation allows the system to use dedicated preambles for terminals requiring reliable access (reducing collisions) while maintaining the option for random selection, thereby resolving the contradiction between access speed and collision probability.
2Reliability
If dedicated preambles are allocated by base station, then preamble collision is reduced, but the system complexity and allocation overhead increase
Solution Approach 1:
Instead of allocating dedicated preambles to all terminals, the base station applies partial action by allocating dedicated preambles only to specific terminals that request initial access or require reliable connectivity. This selective allocation reduces the management overhead and complexity while still achieving collision reduction where needed, avoiding the excessive complexity of universal dedicated allocation.
3Quantity of substance
If preambles are reused after timeout, then resource utilization is improved, but synchronization accuracy for time-sensitive applications deteriorates
Solution Approach 1:
The preamble allocation system is made dynamic by introducing a timeout mechanism. Dedicated preambles are allocated to terminals for a specific duration and are automatically released and reused after the timeout expires. This dynamic approach allows the system to optimize resource utilization by reusing preambles while maintaining synchronization accuracy for active terminals within their allocated time windows, satisfying time-sensitive application requirements.
Data Source
AI summary
An operation method of a terminal in a communication system may comprise: receiving, from a first base station, information on preambles for random access; transmitting, to the first base station, a first message including a preamble selected based on the information on the preambles; receiving, from the first base station, a second message that is a response signal for the first message; transmitting, to the first base station, a third message requesting a preemptive use of the selected preamble during a first preemptive use period; and receiving, from the first base station, a fourth message allowing the preemptive use of the selected preamble during the first preemptive use period, and performing a random access procedure by using the selected preamble during the first preemptive use period.