Dynamic PRACH Resource Allocation for LTE Random Access
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Solution Overview
Problem
In LTE mobile communication systems, ensuring PRACH resources for random access procedures reduces available time-frequency resources for uplink user data transmission, leading to inefficiencies in the random access process.
Innovation Solution
Implementing a communication control method that allows a secondary cell to secure PRACH resources upon request from a primary cell, enabling the user terminal to transmit a random access preamble using these resources, and subsequently releasing them for other applications once secured.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PRACH resources are ensured for random access procedures, then random access capability is improved, but available time-frequency resources for uplink user data transmission decrease
Solution Approach 1:
The patent implements dynamic PRACH resource allocation where the secondary cell activates or releases PRACH resources based on real-time random access requirements. The base station receives indication information about whether the user terminal needs to perform random access on the secondary cell, and accordingly configures or releases the PRACH resources. This dynamic adjustment resolves the contradiction by making PRACH resources available only when needed, rather than permanently allocating them.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the secondary cell with the capability to receive PRACH resources upon request, but not actually allocating them until the need is indicated. The base station prepares the resource allocation mechanism in advance, and only when the user terminal indicates random access requirement does the actual resource securing occur. This allows the system to be ready for random access when needed while maintaining resource efficiency when not needed.
2Reliability
If PRACH resources are permanently allocated in the secondary cell, then random access reliability is improved, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent implements dynamic switching between resource allocation states. The secondary cell transitions from a state where PRACH resources are not allocated (saving resources) to a state where they are allocated (enabling random access) based on the indication information received from the base station. This dynamic state transition resolves the contradiction between maintaining reliability and avoiding resource waste.
Solution Approach 2:
The patent applies the principle of discarding and recovering resources. When the user terminal does not need to perform random access on the secondary cell, the PRACH resources are released back to the resource pool for other uses. When random access is needed, the resources are secured again. This cyclical allocation and release pattern ensures resources are not permanently tied up, improving overall utilization efficiency while maintaining reliability when needed.
3Productivity
If the secondary cell secures PRACH resources upon request, then random access efficiency is improved, but inter-cell coordination complexity increases
Solution Approach 1:
The patent implements a universal indication mechanism that can be applied across multiple cells and user terminals. The base station uses a standardized method to indicate random access requirements to the secondary cell, and the secondary cell follows a standardized procedure for resource allocation. This universal approach, while adding coordination, creates a scalable and systematic solution that improves random access efficiency across the entire carrier aggregation system.
Data Source
AI summary
A communication control method used in a mobile communication system in which a UE 100 is capable of simultaneously using a plurality of cells. The communication control method comprises the steps of: transmitting a PRACH securing request to request a securing of a PRACH resource, from a cell 1 having a connection with the UE 100 to a cell 2 having no connection with the UE 100; securing, by the cell 2 that receives the PRACH securing request, the PRACH resource; and transmitting a random access preamble by using the PRACH resource, from the UE 100 to the cell 2.