Air Interface Synchronization via Periodic Listening RS and Feedback
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Solution Overview
Problem
In high-density small cell deployments, existing air interface synchronization methods fail to ensure that source cells correctly determine whether they are selected, leading to inefficient energy usage and potential disruptions in air interface synchronization, as they do not provide timely feedback on selection status.
Innovation Solution
The method involves an eNB obtaining and sharing listening RS subframe position information with adjacent cells, allowing them to mute at specific subframes and determine their selection status through identification information or command messages via S1, X2, or wireless interfaces, ensuring accurate source cell selection and synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If source cells continuously transmit listening RS to ensure synchronization availability, then synchronization reliability is improved, but energy consumption increases
Solution Approach 1:
The source cell transmits listening RS only in specific periodic subframes (MBSFN subframes) rather than continuously. The target cell is configured with specific subframe positions where it can receive listening RS, creating a periodic transmission pattern that reduces energy consumption while maintaining synchronization capability.
Solution Approach 2:
The target cell sends feedback information to the source cell indicating whether it has successfully acquired synchronization. Based on this feedback, the source cell can adjust its listening RS transmission behavior, stopping transmission when not needed and resuming when required, thereby optimizing energy usage while ensuring synchronization reliability.
2Reliability
If source cells send listening RS in all subframes to ensure continuous synchronization, then synchronization availability is improved, but system complexity increases
Solution Approach 1:
The system uses periodic MBSFN subframes for listening RS transmission instead of continuous transmission. This periodic structure simplifies the system by creating predictable, periodic patterns rather than requiring complex continuous monitoring and transmission mechanisms.
Solution Approach 2:
The target cell is pre-configured with information about which subframes will contain listening RS (through RRC configuration). This preliminary configuration allows the target cell to prepare reception in advance for specific subframes, reducing the need for complex real-time detection and decision-making mechanisms.
3Ease of operation
If the existing synchronization process is used without feedback, then device operation simplicity is maintained, but information loss occurs regarding source cell selection status
Solution Approach 1:
A feedback mechanism is introduced where the target cell informs the source cell whether it has successfully acquired synchronization. This feedback loop provides the source cell with information about its selection status without significantly complicating the overall operation, as the feedback uses existing signaling resources.
Solution Approach 2:
The source cell uses the feedback information to autonomously adjust its own transmission behavior. When it receives indication that synchronization has been acquired, it can independently stop transmitting listening RS, and when synchronization is lost, it can resume transmission, making the system self-regulating.
Data Source
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AI summary
An air interface synchronization method and a system are disclosed in the present invention. The method includes: a base station in a target cell sends request information for intercepting to a center node, and the request information carries the information about a candidate source cell; the center node determines air interface synchronization interception relation, sends source cell determination information and location information of intercepted sub-frame of the RS to a base station in the source cell, and sends intercepted source cell determination information and location information of intercepted sub-frame to the base station in the target cell.