LAA SCell Timing Reference via Scheduling Carrier Selection
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Solution Overview
Problem
In wireless communication systems, the lack of guaranteed downlink transmissions over License Assisted Access (LAA) secondary cells (SCells) within secondary timing advance groups (sTAGs) leads to difficulties for user equipment (UEs) in determining the appropriate timing for uplink transmissions, resulting in increased latency and reduced throughput.
Innovation Solution
The system improves the likelihood of UEs receiving a downlink timing reference by dynamically adding LAA SCells to an sTAG based on criteria such as scheduling carrier determination, connected mode discontinuous reception (CDRX) status, and downlink transmission frequency, allowing UEs to identify a reliable downlink timing reference for uplink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LAA SCells are used in sTAGs, then system throughput is improved, but downlink transmission reliability deteriorates
Solution Approach 1:
The patent introduces a scheduling carrier as an intermediary element that coordinates between LAA SCells and UEs. The scheduling carrier provides scheduling information that enables UEs to determine timing references for uplink transmissions, thereby mediating the reliability issue while maintaining the throughput benefits of LAA SCells
Solution Approach 2:
The patent implements preliminary action by having the base station determine scheduling carriers and provide scheduling information to UEs before uplink transmissions occur. This preliminary scheduling mechanism ensures that UEs have the necessary timing reference information in advance, preventing transmission delays while utilizing LAA SCells
2Measurement precision
If downlink transmission timing reference is not available, then uplink transmission timing accuracy is improved (UE can suspend transmission), but system latency increases
Solution Approach 1:
The patent implements feedback mechanisms where the base station provides scheduling information and timing reference information to UEs based on uplink transmission requirements. This feedback loop ensures UEs can accurately determine timing references without suspending transmissions, maintaining both timing accuracy and reducing latency
Solution Approach 2:
The patent enables UEs to self-determine timing references for uplink transmissions by providing them with scheduling information from the scheduling carrier. This self-service capability allows UEs to autonomously establish timing accuracy without requiring continuous downlink transmissions, thereby reducing latency while maintaining precision
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described. A wireless system may support efficient techniques for adding license assisted access (LAA) secondary cells (SCells) to a secondary timing advance group (sTAG). For example, a base station may determine whether to add an LAA SCell to an sTAG based on whether the LAA SCell is a scheduling carrier for a user equipment (UE). That is, the base station may determine whether to add an LAA SCell to an sTAG based on whether a UE scheduled to communicate over the LAA SCell is self-scheduled over the LAA SCell or cross-carrier scheduled over another cell. As such, the wireless system may improve the likelihood that a UE may receive a downlink transmission over an LAA SCell in an sTAG that the UE may use to determine a downlink timing reference for an uplink transmission over the LAA SCell.