TDD PUCCH HARQ Resource Allocation via eCCE Index and Offset
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Solution Overview
Problem
Current LTE systems face challenges in efficiently determining PUCCH resources for HARQ-ACK transmission in TDD mode, particularly due to asymmetry between uplink and downlink subframes, which affects PUCCH resource allocation and utilization, especially with the introduction of ePDCCH, leading to complexities in scheduler design and resource management.
Innovation Solution
A method for determining PUCCH resources based on the lowest eCCE index of received DCI, combined with a device-specific offset and index calculations, allows for sequential allocation of PUCCH resources across associated downlink and uplink subframes, optimizing resource utilization and reducing blocking probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PUCCH resources are allocated for HARQ-ACK transmission in TDD mode with ePDCCH, then resource allocation efficiency is improved, but blocking probability increases due to asymmetry between uplink and downlink subframes
Solution Approach 1:
The patent segments PUCCH resource allocation by creating separate resource pools for different downlink subframes associated with an uplink subframe. This is achieved by introducing an offset parameter that divides the PUCCH resource space into distinct segments, allowing independent management of resources for each downlink subframe, thereby reducing resource conflicts and blocking probability
Solution Approach 2:
The patent introduces a new dimension to PUCCH resource allocation by adding the offset parameter that differentiates resource allocation across multiple downlink subframes. This dimensional extension allows the system to handle TDD asymmetry more effectively by providing additional resource allocation degrees of freedom, transforming a one-dimensional resource index into a multi-dimensional resource allocation scheme
2Adaptability or versatility
If PUCCH resources are allocated based on eCCE index with device-specific offset, then resource allocation flexibility is improved, but eNB scheduler complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring device-specific offset values through higher-layer signaling before actual resource allocation occurs. This pre-configuration step establishes a foundation that simplifies real-time scheduling decisions, as the eNB only needs to combine the pre-determined offset with the eCCE index rather than performing complex calculations during scheduling
Solution Approach 2:
The device-specific offset acts as an intermediary parameter that bridges the gap between the eCCE index and the final PUCCH resource index. This intermediary simplifies the mapping relationship by providing a configurable offset that can be adjusted independently, reducing the complexity of direct mapping while maintaining flexibility
Data Source
AI summary
PUCCH resource determination for HARQ-ACK transmission in response to ePDCCH-scheduled PDSCH or ePDCCH-indicated SPS release in a TDD radio communication system. Downlink control information (DCI) is received in a downlink subframe via an Enhanced Physical Downlink Control Channel (ePDCCH). A resource index for a Physical Uplink Control Channel (PUCCH) resource is determined, based on the lowest enhanced Control Channel Element (eCCE) index of the received DCI, a device-specific offset value, and an index i that identifies the downlink subframe in a pre-determined set of one or more downlink subframes associated with an uplink subframe. The PUCCH resource is determined according to a formula that results in a sequential allocation of PUCCH resources in the uplink subframe with respect to the downlink subframes associated with the uplink subframe, for each of a plurality of sets of ePDCCH resources. HARQ feedback is transmitted in the uplink subframe, in the indexed PUCCH resource.