LBT Subframe Selection for Wireless Carrier Timing
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Solution Overview
Problem
Current multicarrier communication systems face challenges in efficiently managing signal timing and resource allocation across multiple carriers, particularly in scenarios with high data traffic and increasing user demands, where traditional methods struggle to optimize network capacity and spectral efficiency.
Innovation Solution
The implementation of carrier aggregation (CA) and dual connectivity (DC) technologies, combined with Listen-before-Talk (LBT) mechanisms, enables dynamic resource allocation and efficient use of licensed and unlicensed spectrum, allowing for seamless mobility and high data rates by synchronizing timing across multiple carriers and adapting to changing network loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation and dual connectivity are implemented to increase network capacity and data rates, then spectral efficiency and network capacity improve, but device complexity and interference management difficulty increase
Solution Approach 1:
The patent segments carriers into different groups (e.g., primary carriers and secondary carriers, or carriers with different LBT requirements) and applies different timing advance groups (TAGs) to each segment. This allows independent timing management for different carrier segments, reducing the overall complexity of managing aggregated carriers while maintaining high network capacity.
Solution Approach 2:
The patent implements dynamic timing advance adjustment where timing advance values are updated independently for different timing advance groups based on their specific propagation conditions and LBT outcomes. This dynamic adaptation allows the system to handle varying network conditions across multiple carriers without requiring complete reconfiguration, thus managing complexity while maximizing productivity.
2Object-affected harmful factors
If Listen-before-Talk mechanisms are applied across multiple carriers to reduce interference, then interference management improves, but transmission delays and loss of time increase
Solution Approach 1:
The patent performs Listen-before-Talk procedures in advance before actual data transmission on unlicensed carriers. By conducting LBT early and determining timing advance values beforehand, the system prepares transmission parameters in advance, allowing faster actual data transmission once channel access is granted, thus reducing the impact of transmission delays.
Solution Approach 2:
The patent implements periodic LBT procedures at defined intervals and uses semi-persistent scheduling where timing advance values are valid for multiple transmission opportunities. This periodic approach reduces the frequency of full LBT procedures, thereby reducing overall transmission delays while maintaining interference management through regular channel assessments.
3Reliability
If timing advance groups are used to synchronize uplink transmissions across multiple carriers, then spectral efficiency improves, but device complexity and processing overhead increase
Solution Approach 1:
The patent divides aggregated carriers into multiple timing advance groups where each group shares a common timing advance value. This segmentation reduces the total number of timing advance parameters that need to be managed and transmitted, lowering processing overhead while maintaining synchronization within each group. Carriers with similar propagation characteristics are grouped together to minimize synchronization errors.
Solution Approach 2:
The timing advance mechanism is designed to be universally applicable across different carrier types (licensed and unlicensed, FDD and TDD) through a unified timing advance group framework. This multi-functional approach allows the same basic mechanism to handle synchronization for diverse carrier configurations, reducing the need for carrier-specific complexity while maintaining reliable synchronization.
Data Source
AI summary
A first base station receives a first message comprising one or more first parameters identifying one or more first subframes as a listen-before-talk (LBT) subframe. One or more second subframes are selected as an LBT subframe by the first base station employing the one or more first parameters. An LBT procedure is performed in a subframe in the one or more subframes. A burst is transmitted when the LBT procedure indicates a clear channel.