PUCCH Resource Allocation for HARQ-ACK in LTE
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Solution Overview
Problem
In LTE radio communication systems, PUCCH resources allocated for reduced and non-reduced processing time TTI overlap, leading to contention between terminal apparatuses, which affects efficient HARQ-ACK transmission and reception.
Innovation Solution
A method is introduced to determine PUCCH resources for HARQ-ACK transmission based on a shift field in the DCI format, using a combination of conditions such as reduced timing capability, HARQ-ACK transmission timing, and search space mapping, to prevent resource overlap and ensure efficient allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PUCCH resources are allocated for both reduced and non-reduced processing time TTI in the same uplink subframe, then both terminal apparatuses with and without reduced processing time capability can transmit HARQ-ACK, but resource overlap and contention occur between terminal apparatuses
Solution Approach 1:
The PUCCH resources are segmented into different uplink subframes based on the processing time capability of terminal apparatuses. Terminal apparatuses with reduced processing time capability transmit HARQ-ACK in earlier uplink subframes (e.g., subframe n), while terminal apparatuses with non-reduced processing time capability transmit in later uplink subframes (e.g., subframe n+1 or n+2). This temporal segmentation eliminates resource overlap and contention between the two types of terminal apparatuses while maintaining system compatibility.
2Loss of time
If HARQ-ACK transmission timing is advanced for reduced processing time TTI, then latency is reduced, but PUCCH resource overlap with non-reduced processing time terminal apparatuses occurs
Solution Approach 1:
The base station acts as an intermediary that manages and coordinates PUCCH resource allocation. It identifies the processing time capability of each terminal apparatus and assigns appropriate uplink subframes for HARQ-ACK transmission accordingly. This intermediary management ensures that reduced processing time terminal apparatuses can transmit early (reducing latency) without causing resource contention, as the base station prevents overlapping allocations by coordinating between different terminal types.
Data Source
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AI summary
A terminal apparatus includes: a reception unit configured to: receive a PDCCH or an EPDCCH with a DCI format and a first RRC parameter, and decode a PDSCH according to detection of the PDCCH or the EPDCCH; and a transmission unit configured to: transmit a HARQ-ACK in a subframe n according to detection of the PDSCH in a subframe n-k. Whether the PUCCH resource is given at least based on the first RRC parameter is determined at least based on part of or all of the first condition and the second condition described below: • first condition: the value k, and • second condition: which one of CSS and USS is a search space to which a physical downlink control channel including the DCI format is mapped.