TDD-FDD Aggregation HARQ Timing for LTE Spectrum Efficiency
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Solution Overview
Problem
In LTE systems, the coexistence of FDD and TDD frequency bands leads to interference issues due to adjacent channel operation, resulting in inefficient spectrum resource utilization and waste, particularly in the 2.6 GHz band, where the FDD/TDD hybrid scheme causes significant waste of spectrum resources, hindering TDD development and international promotion.
Innovation Solution
Implementing a method where TDD and FDD cells aggregate, with TDD as the primary serving cell and FDD as the secondary serving cell, by grouping downlink subframes of the FDD secondary serving cell using different HARQ timing relationships to determine uplink subframes for transmitting HARQ-ACK messages, ensuring efficient HARQ-ACK message distribution and minimizing feedback delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FDD and TDD frequency bands are operated adjacently in the 2.6 GHz band, then spectrum resource utilization is improved, but interference issues occur and spectrum resources are wasted
Solution Approach 1:
The patent segments downlink subframes of the FDD secondary serving cell into different groups (first group and second group) based on TDD uplink-downlink configuration. Different subframe groups are assigned different HARQ timing relationships, allowing differentiated handling of interference scenarios while maintaining overall spectrum efficiency.
Solution Approach 2:
The patent applies different HARQ timing relationships to different downlink subframe groups rather than using a uniform timing relationship for all subframes. This local differentiation allows optimization of ACK/NACK feedback timing for specific subframes affected by interference, while maintaining efficient timing for other subframes.
2Productivity
If FDD and TDD aggregate with TDD as primary and FDD as secondary serving cell, then downlink throughput is improved, but HARQ-ACK message distribution becomes complex
Solution Approach 1:
The patent divides downlink subframes into distinct groups with different HARQ timing relationships, creating a structured approach to manage the complexity of HARQ-ACK message distribution in TDD-FDD aggregated systems.
Solution Approach 2:
The patent introduces dynamic adaptation by selecting different HARQ timing relationships based on the specific downlink subframe group and TDD uplink-downlink configuration, allowing the system to flexibly adjust to varying interference conditions and throughput requirements.
3Device complexity
If uniform HARQ timing relationship is used for all downlink subframes, then device complexity is reduced, but feedback delay increases
Solution Approach 1:
The patent applies different HARQ timing relationships to different downlink subframe groups, allowing optimization of feedback delay for specific subframes while maintaining manageable device complexity through a structured grouping approach.
Data Source
AI summary
Disclosed are a method and device for sending answer information, wherein, when a frequency division duplex (FDD) and a time division duplex (TDD) aggregate, where a TDD cell serves as a primary serving cell and a FDD cell works as a secondary serving cell, a user equipment (UE) groups downlink subframes of the FDD secondary serving cell, and different downlink subframe groups use different hybrid automatic repeat request (HARQ) timing relationships, determines uplink subframes where HARQ-ACK acknowledgment messages corresponding to physical downlink shared channels (PDSCHs) of the downlink subframe groups are transmitted, and sends the HARQ-ACK messages on the determined uplink subframes.