Bundled ACK/NACK Feedback for TDD Uplink Constraints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, particularly in TDD mode, the limited uplink radio resources lead to restricted ACK/NACK signal transmission, resulting in potential packet loss and reduced recovery capability due to the asymmetrical allocation of downlink and uplink subframes, where a single UE must transmit fewer ACK/NACK signals than the number of received downlink packets.
Innovation Solution
A method where a UE receives a bundling indicator for downlink subframes, generates a representative ACK/NACK signal based on successful reception of codewords, and transmits this signal on an uplink channel, allowing for efficient ACK/NACK bundling to maximize recovery capability and minimize packet loss, even with fewer ACK/NACK signals than downlink packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If TDD mode is used with asymmetrical allocation of downlink and uplink subframes, then the system can allocate time having different lengths to uplink and downlink, but the number of ACK/NACK signals to be transmitted is restricted, leading to potential packet loss
Solution Approach 1:
The patent combines multiple ACK/NACK signals into a single bundled signal that is transmitted together. Instead of transmitting individual ACK/NACK signals for each downlink subframe separately, the method groups them into one bundled feedback signal, thereby reducing the total number of signals that need to be transmitted while maintaining complete feedback information.
Solution Approach 2:
The patent segments the feedback information by associating specific downlink subframes with specific uplink subframes. The bundling indicator divides the downlink subframes into groups that can be independently tracked and feedbacked, allowing the system to manage the asymmetrical time allocation while ensuring reliable feedback transmission.
2Productivity
If the number of ACK/NACK signals is reduced to match limited uplink resources, then efficient use of feedback radio resources is achieved, but recovery capability is reduced when fewer signals are fed back than downlink packets
Solution Approach 1:
Multiple ACK/NACK signals are merged into a single bundled signal that carries feedback information for multiple downlink subframes. This consolidation allows the system to transmit feedback for multiple packets using a single uplink resource allocation, thereby improving resource efficiency while maintaining the ability to recover all transmitted data through the bundled feedback mechanism.
Solution Approach 2:
The patent implements a feedback mechanism where the bundled ACK/NACK signal provides comprehensive feedback information about the reception status of multiple downlink subframes. This feedback allows the transmitter to accurately identify which packets were successfully received and which require retransmission, thereby maintaining high recovery capability despite the reduced number of individual signal transmissions.
3Productivity
If ACK/NACK signals are transmitted in limited uplink subframes, then the system can operate efficiently with asymmetrical time allocation, but packet loss increases when the number of feedback signals is less than the number of downlink packets
Solution Approach 1:
The patent merges multiple packet feedback signals into a single bundled ACK/NACK signal that contains comprehensive information about the reception status of all downlink subframes. This merging approach allows the system to operate efficiently with limited uplink subframes while preventing information loss, as the bundled signal preserves complete feedback data for all transmitted packets.
Solution Approach 2:
The patent employs a bundling indicator that is transmitted beforehand to indicate the number and arrangement of bundled downlink subframes. This preliminary information allows the receiver to properly configure its feedback transmission, ensuring that all packet loss information is captured and transmitted in the bundled signal, thereby preventing information loss while maintaining efficient system operation.
Data Source
AI summary
A method of performing HARQ performed by a user equipment (UE) is provided. The method includes receiving a bundling indicator which indicates the number of bundled downlink subframes, determining whether at least one bundled downlink subframe is missed by comparing the bundling indicator with the number of detected bundled downlink subframes, generating a representative ACK/NACK signal when no bundled downlink subframe is missed, and transmitting the representative ACK/NACK signal on an uplink channel. Recovery capability is maximized and the packet loss is reduced in such a situation that less number of ACK/NACK signals are fed back than that of downlink packets.