Secondary Cell Uplink Synchronization via RRC Configuration
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Solution Overview
Problem
In LTE Release 11, there is a lack of solutions for uplink synchronization between user equipment and base stations on secondary cells, particularly in uncoordinated, non-collocated site and frequency repeater scenarios, where initial timing alignment is required for uplink transmission.
Innovation Solution
A method involving a base station sending a Radio Resource Control (RRC) configuration request to user equipment to perform RRC configuration and uplink synchronization, with the option to retrigger synchronization using PDCCH order signaling if initial synchronization fails, allowing for non-contention or contention processes based on dedicated preambles and Timing Advance information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the secondary cell is configured via RRC Connection Reconfiguration without initial timing alignment, then the configuration procedure is simplified and faster, but uplink synchronization cannot be established in non-collocated site scenarios
Solution Approach 1:
The patent performs timing advance measurement and synchronization preparation in advance during the RRC connection reconfiguration phase. The base station measures the timing advance of the secondary cell before activating it, ensuring that uplink synchronization is already prepared when the secondary cell becomes active, thus avoiding synchronization delays while maintaining fast configuration.
Solution Approach 2:
The patent configures random access resources and synchronization parameters in advance during RRC connection reconfiguration, even though they may not be immediately needed. This preparatory configuration ensures that when uplink synchronization is required, the necessary resources and parameters are already in place, preventing synchronization failures in non-collocated site scenarios.
2Ease of operation
If the secondary cell uses the same timing advance as the primary cell, then the user equipment does not need to perform initial timing alignment, but this approach fails in uncoordinated and frequency repeater scenarios
Solution Approach 1:
The patent dynamically determines the timing advance configuration based on the specific deployment scenario. For collocated sites, the secondary cell can use the same timing advance as the primary cell, simplifying the procedure. For non-collocated sites and frequency repeaters, the system dynamically switches to performing separate timing advance measurements and configurations, ensuring adaptability across different deployment scenarios while maintaining ease of operation where applicable.
3Device complexity
If PDCCH order signaling is only transmitted on the primary cell, then the signaling structure remains simple, but uplink synchronization for secondary cells cannot be retriggedered
Solution Approach 1:
The patent extends the functionality of PDCCH order signaling to include secondary cell synchronization retriggering. The same PDCCH order signaling mechanism used for primary cell synchronization is made universal to also trigger uplink synchronization for secondary cells. This allows a single signaling structure to serve multiple purposes: maintaining simplicity while enabling synchronization retriggering for both primary and secondary cells across different scenarios.
Data Source
AI summary
Embodiments provide a method for initializing a secondary cell in a cellular communication system. The method may comprise: receiving from a base station a Radio Resource Control RRC configuration request for the secondary cell to perform a RRC configuration; and in response to receiving the RRC configuration request, performing uplink synchronization with the base station in the secondary cell.