Terminal Device LBT Control for Shared Frequency Band Efficiency
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Solution Overview
Problem
Conventional LTE systems are not designed to operate efficiently in unallocated or shared frequency bands, leading to challenges in frequency band management and communication efficiency.
Innovation Solution
The development of a terminal device and base station device that utilize advanced scheduling and resource allocation techniques, including listen-before-talk (LBT) and carrier aggregation, to enable efficient communication in unallocated or shared frequency bands, allowing for the use of unlicensed spectrum and coexistence with other systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional LTE is used in unallocated or shared frequency bands, then the system can operate in these bands, but transmission efficiency deteriorates due to lack of specific management techniques
Solution Approach 1:
The patent implements dynamic Listen-Before-Talk (LBT) mechanisms that adapt transmission behavior based on real-time channel conditions. The base station and terminal devices dynamically adjust their channel access procedures, transmission timing, and resource allocation based on detected channel occupancy and interference levels, enabling efficient operation in shared unlicensed bands while maintaining high transmission efficiency
Solution Approach 2:
The system changes key operational parameters including LBT category selection (Cat-1, Cat-2, Cat-3, Cat-4), contention window sizes, transmission power levels, and resource block allocations based on channel conditions. These parameter adjustments optimize transmission efficiency for different scenarios in unlicensed spectrum while maintaining adaptability across various frequency band configurations
2Productivity
If LBT and carrier aggregation techniques are implemented, then transmission efficiency improves in shared frequency bands, but device complexity increases
Solution Approach 1:
The patent introduces a dedicated LBT control mechanism that acts as an intermediary between the physical layer transmission functions and the higher-layer protocol stack. This control entity coordinates channel sensing, clear channel assessment (CCA), and transmission timing across multiple component carriers, managing the complexity of LBT operations while maximizing transmission efficiency through centralized control
Solution Approach 2:
The system segments the carrier aggregation operation into independent LBT control units for each component carrier or carrier group. Each segment can perform LBT procedures independently or in coordinated fashion, allowing the system to manage complexity by dividing the overall transmission task into smaller, more manageable units that can be controlled separately
3Adaptability or versatility
If unlicensed spectrum is utilized through LAA, then frequency band availability increases, but communication reliability deteriorates due to shared access with other systems
Solution Approach 1:
The patent implements preliminary channel sensing and Clear Channel Assessment (CCA) procedures before actual data transmission. The base station and terminal devices perform LBT operations in advance to detect channel occupancy by other systems (such as Wi-Fi), and only proceed with transmission when the channel is determined to be clear or when interference can be managed, thereby maintaining reliability while utilizing unlicensed spectrum
Solution Approach 2:
The system employs feedback mechanisms where transmission outcomes, channel conditions, and interference levels are continuously monitored and reported back to the LBT control entity. This feedback loop enables dynamic adjustment of LBT parameters, transmission power, and resource allocation to maintain reliable communication in the presence of other systems sharing the unlicensed frequency band
Data Source
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AI summary
A cell using an unallocated frequency band or a shared frequency band is efficiently controlled. A terminal device includes a reception unit configured to receive a physical downlink control channel (PDCCH) in a secondary cell having a frame structure type 3. Upon the terminal device detecting, in the secondary cell having the frame structure type 3, the PDCCH having downlink control information (DCI) in a subframe n, the terminal device assumes a configuration of occupied OFDM symbols in the secondary cell in accordance with a field in the DCI detected in the subframe n.