HARQ Process Management in LTE Uplink Carrier Aggregation
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Solution Overview
Problem
Current technologies lack a comprehensive method for introducing asynchronous HARQ in the uplink, switching between synchronous and asynchronous HARQ, and processing HARQ buffers efficiently in LTE communication systems.
Innovation Solution
A terminal device and base station device configuration that enables efficient communication by managing multiple HARQ processes through carrier aggregation, switching between synchronous and asynchronous HARQ based on RRC layer information, and processing HARQ buffers by identifying HARQ processes related to uplink grants within the MAC layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If synchronous HARQ is used in the uplink, then the HARQ process management is simple and fixed, but the communication flexibility and adaptability are limited
Solution Approach 1:
The patent implements dynamic HARQ process management where the HARQ process number is determined by formulas that adapt to different subframe configurations. The system can dynamically switch between synchronous and asynchronous HARQ modes based on RRC layer configuration, allowing flexible adaptation to varying communication scenarios while maintaining manageable complexity through standardized determination methods.
Solution Approach 2:
The patent changes the HARQ process determination parameters based on RRC layer information and subframe configurations. By using configurable parameters in the determination formulas and allowing RRC-layer-controlled switching between HARQ modes, the system achieves adaptability without requiring completely different management mechanisms for each scenario.
2Adaptability or versatility
If asynchronous HARQ is introduced in the uplink, then the communication flexibility improves, but the method for identifying HARQ processes and managing buffers becomes complex and unclear
Solution Approach 1:
The patent establishes predetermined formulas for determining HARQ process numbers based on subframe indices and configurable parameters. These formulas are configured in advance through RRC layer signaling, allowing the terminal to autonomously determine the correct HARQ process without complex real-time identification procedures, thus reducing the difficulty of HARQ process detection.
Solution Approach 2:
The patent implements a feedback mechanism where the network configures HARQ-related parameters through RRC layer signaling based on terminal capabilities and network conditions. This feedback loop allows the system to optimize HARQ process identification methods according to actual communication scenarios, reducing identification difficulty while maintaining flexibility.
3Productivity
If multiple HARQ processes are managed through carrier aggregation, then the communication efficiency improves, but the HARQ buffer management and process switching become more complex
Solution Approach 1:
The patent segments HARQ buffer management by associating specific buffers with specific HARQ processes and component carriers. Each HARQ process has its dedicated buffer management, allowing independent handling of multiple processes without requiring complex global buffer management. This segmentation approach enables efficient parallel processing while maintaining manageable complexity through modular buffer organization.
Solution Approach 2:
The patent implements a universal HARQ management framework that handles both synchronous and asynchronous HARQ modes, as well as multiple component carriers, through a unified set of determination formulas and management procedures. This multi-functional approach allows the same management mechanism to serve multiple purposes, improving communication efficiency across different scenarios without proportionally increasing complexity.
Data Source
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AI summary
A terminal device receives a control channel including a DCI format and transmits a PUSCH, in which the DCI format includes an uplink index and information for indicating a HARQ process number; when both a first bit and a second bit of the uplink index are set to 1, the HARQ process number in the PUSCH corresponding to the first bit is X and the HARQ process number in the PUSCH corresponding to the second bit is mod (X+1, Z); the mod (X+1, Z) is a function outputting a remainder when dividing (X+1) by Z; the X is determined based on the information for indicating the HARQ process number; and the Z is a value identical to a maximum number of HARQ processes in a serving cell determined by an uplink/downlink configuration.