ACK/NACK Resource Allocation in TDD Wireless Systems
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Solution Overview
Problem
In time division duplex (TDD)-based wireless communication systems, there is a need for an efficient method to transmit acknowledgement signals (ACK/NACK) across multiple serving cells, as existing methods face challenges in accurately allocating resources for channel selection, leading to potential mismatches between base stations and user equipment.
Innovation Solution
A method is proposed where M downlink subframes associated with an uplink subframe in each of two serving cells determine four candidate resources, selecting one resource for transmitting ACK/NACK, with specific criteria based on physical downlink shared channel (PDSCH) and semi-persistent scheduling (SPS) release PDCCH indicators, to effectively manage resource allocation across multiple serving cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If channel selection method is used to transmit HARQ ACK/NACK in TDD system with multiple serving cells, then the information amount of HARQ ACK/NACK can be transmitted with limited transmission bits, but resource allocation mismatch between base station and user equipment occurs
Solution Approach 1:
The patent applies preliminary action by pre-configuring four candidate resources (first, second, third, and fourth resources) for ACK/NACK transmission before actual data transmission. The base station and user equipment both know these candidate resources in advance, eliminating allocation mismatches. The specific resource is selected based on predetermined criteria involving PDSCH reception status and SPS release PDCCH indicators, ensuring both parties select the same resource without ambiguity.
2Measurement precision
If four candidate resources are allocated for ACK/NACK transmission in multiple serving cells, then resource allocation accuracy improves, but device complexity increases
Solution Approach 1:
The patent uses parameter changes by establishing clear selection criteria based on transmission parameters: whether PDSCH is received in specific serving cells and whether SPS release PDCCH is detected. These binary parameters (PDSCH received/not received, SPS release PDCCH detected/not detected) map to specific resource selections, providing a deterministic algorithm that reduces complexity while maintaining precision.
Data Source
AI summary
Provided is a method of transmitting ACK/NACK in a TDD-based wireless communication system. The method includes: receiving M downlink subframes associated with an uplink subframe n in each of two serving cells; determining four candidate resources based on the M downlink subframes received in each of the two serving cells; and transmitting an ACK/NACK response for the M downlink subframes by using one resource selected from the four candidate resources in the uplink subframe n, wherein the two serving cells includes a first serving cell and a second serving cell, and wherein among the four candidate resources, a first resource and a second resource are associated with a PDSCH or a SPS release PDCCH for releasing semi-persistent scheduling received in the first serving cell, and a third resource and a fourth resources are associated with a PDSCH received in the second serving cell.