Terminal PUCCH Format Selection for HARQ-ACK in Multi-Cell LTE
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Solution Overview
Problem
In LTE communication systems, there is a challenge in efficiently transmitting and receiving uplink control information due to limitations in processing time and subframe alignment between primary and secondary cells, particularly in scenarios with FDD and TDD configurations.
Innovation Solution
The solution involves a terminal apparatus and base station apparatus that utilize multiple serving cells, with the terminal apparatus selecting appropriate PUCCH formats (1a or 1b) for transmitting HARQ-ACK based on scheduling requests and higher layer parameters, and the base station apparatus adapting to receive these transmissions efficiently by aligning subframes accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PUCCH format 1b with channel selection is used for HARQ-ACK transmission, then the transmission capacity is improved, but the processing time requirement increases
Solution Approach 1:
The patent dynamically selects between PUCCH format 1b with channel selection and PUCCH format 1a/1b based on the value of subframe q. When subframe q allows sufficient processing time, PUCCH format 1b with channel selection is used for higher transmission capacity. When subframe q indicates tight timing constraints, PUCCH format 1a or 1b is selected to meet the processing time requirement. This dynamic adaptation resolves the contradiction between transmission capacity and processing time requirements.
2Adaptability or versatility
If multiple serving cells with FDD and TDD configurations are used, then the system versatility is improved, but the subframe alignment complexity increases
Solution Approach 1:
The patent applies different PUCCH formats and transmission methods to different serving cells based on their specific characteristics. For FDD primary cells, one transmission method is applied, while for TDD secondary cells with different uplink-downlink configurations, different transmission methods are applied. This local differentiation allows the system to support multiple FDD/TDD configurations simultaneously while managing subframe alignment complexity through cell-specific optimization.
Solution Approach 2:
The patent changes the transmission parameters (PUCCH format, transmission method) based on the subframe q value and the duplexing mode of each serving cell. By adapting parameters according to the specific cell configuration and timing requirements, the system achieves versatility in supporting multiple FDD/TDD configurations while maintaining manageable complexity through parameter optimization.
3Loss of time
If HARQ-ACK transmission timing is shortened, then the latency is reduced, but the transmission reliability may deteriorate
Solution Approach 1:
The patent dynamically adjusts the HARQ-ACK transmission method based on the timing relationship indicated by subframe q. When the timing allows sufficient processing time, more robust transmission methods are used to ensure reliability. When tighter timing constraints exist, the system selects transmission methods that can meet the latency requirement while maintaining adequate reliability through appropriate format selection and resource allocation.
Data Source
AI summary
A terminal apparatus receives a transport block in a primary cell, selects a first transmission method in a case that a scheduling request is a negative scheduling request, HARQ-ACK is transmitted in a subframe n, and a subframe q in a secondary cell does not correspond to any of first prescribed subframes, selects a second transmission method in a case that the subframe q corresponds to one of the first prescribed subframes, and transmits the HARQ-ACK in a PUCCH resource for the HARQ-ACK, wherein the subframe q is given by n−4 in a case that a first higher layer parameter for the secondary cell is not configured, and the subframe q is given by n−3 in a case that the first higher layer parameter for the secondary cell is configured for the terminal apparatus 1.