Uplink ACK/NACK Resource Allocation in TDD Systems
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Solution Overview
Problem
In time division duplex wireless communication systems, the asymmetric differences between downlink and uplink subframes lead to inefficient resource allocation, particularly when the number of downlink subframes exceeds the number of uplink subframes, resulting in suboptimal utilization of resources.
Innovation Solution
The implementation of flexible symbol mapping methods, such as symbol first mapping, mixed-symbol/subframe first mapping, and subframe first mapping, which reorder and group downlink control channels across subframes to efficiently allocate resources for uplink acknowledgement/negative-acknowledgement (ACK/NACK) responses, ensuring optimal utilization of reserved resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a one-to-one resource mapping is assumed between UL and DL subframes, then resource allocation is simplified, but resource utilization becomes inefficient in TDD scenarios with asymmetric differences between DL and UL subframes
Solution Approach 1:
The patent segments the resource allocation process by separating the mapping of ACK/NACK resources from a strict one-to-one correspondence. Instead, it divides the allocation into groups where multiple DL subframes can be mapped to a single UL subframe, allowing flexible grouping based on actual traffic needs and asymmetry patterns in TDD systems.
Solution Approach 2:
The patent introduces dynamic resource allocation where the mapping between DL and UL subframes is not fixed but adapts to the actual asymmetric differences. The system dynamically determines the number of ACK/NACK resources needed based on the specific TDD configuration and traffic patterns, rather than assuming a static one-to-one mapping.
2Productivity
If the number of downlink subframes exceeds the number of uplink subframes, then more downlink data can be transmitted, but uplink ACK/NACK resources become insufficient leading to resource waste
Solution Approach 1:
The patent merges multiple downlink subframes into a single uplink acknowledgment opportunity. By allowing multiple DL subframes to share UL ACK/NACK resources, the system efficiently handles scenarios where DL capacity exceeds UL capacity, preventing resource waste while maintaining asymmetric transmission capabilities.
Solution Approach 2:
The patent makes UL ACK/NACK resources universal by enabling them to serve multiple DL subframes simultaneously. This multi-functionality allows the same UL resources to be reused for acknowledging different DL transmissions, optimizing resource utilization in asymmetric TDD configurations.
Data Source
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AI summary
A method is provided to allocate resources for wireless communications. The method includes grouping downlink control channels from multiple subframes and ordering the downlink control channels across downlink subframes having a first control channel element located in a first symbol map and associated with reserved resources for an uplink channel. The method employs a symbol first mapping or a mixed-symbol/subframe first mapping to efficiently allocate the resources.