HARQ ACK/NACK Resource Mapping for TDD Uplink Feedback
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Solution Overview
Problem
In wireless communication systems, particularly in TDD mode, the limited uplink resources for ACK/NACK feedback pose a challenge for efficient Hybrid Automatic Repeat Request (HARQ) operations, as there are not enough resources to handle the feedback for downlink data reception effectively.
Innovation Solution
A method is introduced to semi-statically configure the amount of reserved ACK/NACK resources and efficiently utilize uplink PUCCH resources by grouping and mapping ACK/NACK resources across multiple downlink subframes to a single uplink subframe, allowing for effective HARQ operation in both FDD and TDD modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple downlink subframes are served by a single uplink subframe for ACK/NACK feedback, then the system can support asymmetric services and improve resource utilization in TDD mode, but the uplink resources become insufficient to handle feedback for all downlink data receptions
Solution Approach 1:
The patent segments the limited uplink ACK/NACK resources into multiple resource pools, where each pool corresponds to a specific downlink subframe. This segmentation allows the system to efficiently manage feedback resources by allocating specific resource pools to specific downlink subframes, thereby resolving the resource insufficiency problem while maintaining support for asymmetric services in TDD mode.
Solution Approach 2:
The patent performs preliminary configuration of ACK/NACK resource pools before actual data transmission. By pre-configuring the resource pools and their mappings to downlink subframes, the system prepares the feedback mechanism in advance, enabling efficient resource utilization when asymmetric service patterns occur, thus preventing resource conflicts and insufficiency.
2Productivity
If uplink and downlink are identified according to frequencies in FDD mode, then seamless data transmission can be achieved, but frequency resources are consumed symmetrically which is inefficient for asymmetric services
Solution Approach 1:
The patent creates a universal ACK/NACK resource pooling mechanism that can function across both FDD and TDD modes. The resource pool configuration and mapping methods are designed to be mode-agnostic, allowing the same uplink resources to serve multiple downlink subframes in TDD mode while maintaining compatibility with FDD mode operations, thus achieving multi-functionality and improving resource utilization efficiency.
Data Source
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AI summary
A method of performing hybrid automatic repeat request (HARQ) performed by a user equipment (UE) in a wireless communication system is provided. The method includes receiving downlink assignements in a first subframe, a downlink assignment being transmitted based on a control channel element (CCE), the CCE being a logically indexed resource unit, receiving downlink data on a downlink shared channel in the first subframe, the downlink shared channel being assigned according to the downlink assignments, generating ACK/NACK signals which indicate successful or unsuccessful reception of the downlink data, and transmitting in a second subframe, the ACK/NACK signals by using uplink resources of a subset, the subset being mapped to the first subframe, at least one of the uplink resources being mapped to a plurality of CCEs in the first subframe. Limited resources for uplink feedback are effectively used to support HARQ operation.