FDD-TDD Carrier Aggregation Timing Simplification
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Solution Overview
Problem
Current wireless communication networks face challenges in simplifying multi-carrier communications, particularly when integrating Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD) carrier aggregation, especially for devices without full-duplex capabilities, as existing methods complicate HARQ timing design and scheduling due to differing duplex modes.
Innovation Solution
The method involves determining reference subframe configurations for FDD component carriers based on TDD configurations, allowing communication on FDD carriers according to these configurations for both downlink and uplink directions, and utilizing special subframes appropriately to enhance compatibility and efficiency in carrier aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FDD and TDD carrier aggregation are integrated in current wireless networks, then spectrum utilization and throughput are improved, but HARQ timing design and scheduling become complicated due to differing duplex modes
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting HARQ timing parameters (k values) based on the duplex mode of each component carrier. For TDD CCs, different k values are used for different UL/DL configurations, while FDD CCs use fixed k values. This allows the system to maintain simple HARQ timing for FDD while adapting to TDD requirements, resolving the contradiction between improved throughput from carrier aggregation and the complexity of HARQ timing design.
Solution Approach 2:
The patent segments the carrier aggregation system into distinct FDD and TDD component carriers, each with independently configured HARQ timing parameters. This segmentation allows each carrier type to operate with its own optimized timing structure, preventing the complexity of TDD from propagating to FDD carriers and vice versa, thus maintaining overall system simplicity while enabling high throughput.
2Adaptability or versatility
If FDD and TDD carrier aggregation are integrated, then network flexibility and spectrum usage are improved, but scheduling complexity increases due to asymmetric uplink-downlink configurations
Solution Approach 1:
The patent uses parameter changes by configuring different reference subframe parameters for FDD and TDD component carriers. FDD carriers use reference parameter sets optimized for full-duplex operation, while TDD carriers use parameter sets that accommodate asymmetric UL/DL configurations. This parameter differentiation enables flexible spectrum usage across diverse carrier types while keeping scheduling logic modular and manageable.
Solution Approach 2:
The scheduling mechanism is segmented to handle FDD and TDD carriers independently with carrier-specific timing configurations. This segmentation allows the base station and UE to apply different scheduling rules to different carrier types, reducing overall scheduling complexity while maintaining the ability to flexibly utilize both FDD and TDD spectrum resources.
3Device complexity
If half-duplex devices are excluded from FDD-TDD carrier aggregation, then device implementation complexity is reduced, but market accessibility and deployment efficiency deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-configuring reference subframe parameters for both FDD and TDD component carriers during system setup. This preliminary configuration establishes clear timing relationships and HARQ parameters in advance, enabling half-duplex devices to operate correctly without needing to perform complex real-time calculations or mode switching, thus reducing implementation complexity while improving compatibility.
Solution Approach 2:
The patent introduces reference subframe configurations as an intermediary mechanism that mediates between FDD and TDD carrier requirements. This intermediary layer provides a standardized interface that half-duplex devices can use to understand and adapt to different carrier types, simplifying device implementation while maintaining broad compatibility across FDD-TDD carrier aggregation scenarios.
Data Source
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AI summary
Methods, systems, and devices are described for multi-carrier communications involving one or more TDD component carriers and one or more FDD component carriers in a wireless communications network. Some described embodiments are directed to systems and methods for multi-carrier communications for a half-duplex device. The described methods, systems, and devices may simplify multi-carrier communications, such as the determination of hybrid automatic repeat request (HARQ) and/or scheduling timing with FDD + TDD carrier aggregation.