Cell-Specific ACK/NACK Resource Allocation for Multicast Retransmission
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, efficiently transmitting ACK/NACK responses to broadcast or multicast signals from multiple cells is challenging, leading to resource wastage and inefficiency in retransmissions, as existing methods often require individual HARQ-ACK resources for each user equipment (UE), which can result in unnecessary retransmissions across all cells even if not all UEs fail to receive the initial transmission.
Innovation Solution
A method where the ACK/NACK response is made cell-specific, with the resource or reference signal tailored to the channel quality of the serving cell, allowing for selective retransmissions only in cells where the UE has failed to receive the signal, thereby optimizing resource use by sharing HARQ-ACK resources among UEs and determining the retransmission subset based on channel quality measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual HARQ-ACK resources are allocated for each UE in multi-cell broadcast/multicast, then each UE can provide feedback, but resource wastage increases and unnecessary retransmissions occur across all cells
Solution Approach 1:
The feedback resource allocation is segmented by cell instead of being uniformly allocated across all cells. Each cell has its own dedicated HARQ-ACK resource, allowing selective feedback transmission only in cells where the UE actually received the broadcast/multicast signal. This segmentation eliminates the need for all UEs to allocate resources in all cells, reducing overall resource wastage while maintaining feedback reliability where needed.
Solution Approach 2:
The patent implements cell-specific HARQ-ACK resource allocation where each cell has locally optimized feedback resources tailored to its channel conditions and UE reception status. This local quality approach ensures that feedback resources are only activated and allocated in specific cells where they are actually needed, rather than uniformly across the entire multi-cell system, thereby reducing resource wastage while maintaining necessary feedback capability.
2Reliability
If retransmissions are performed in all cells, then all UEs can potentially receive the signal, but resource utilization decreases when not all UEs need retransmission
Solution Approach 1:
The retransmission process is segmented at the cell level, allowing the network to identify and activate retransmission only in specific cells where UEs failed to receive the initial broadcast/multicast signal. This selective cell-based retransmission approach maintains signal reception reliability for affected UEs while avoiding unnecessary retransmissions in cells where all UEs successfully received the signal, thereby improving overall resource utilization.
Solution Approach 2:
Instead of performing full retransmissions across all cells (excessive action), the patent implements partial retransmission only in the subset of cells where it is actually needed based on UE feedback. This partial action approach ensures sufficient signal reception reliability for UEs that need it while avoiding the resource waste of redundant retransmissions in cells where all UEs successfully decoded the signal.
3Productivity
If cell-specific ACK/NACK resources are used, then resource efficiency improves, but system complexity increases for managing cell-specific configurations
Solution Approach 1:
The patent employs universal cell-specific HARQ-ACK resource allocation patterns that can be applied across multiple cells with consistent configuration rules. By establishing a universal framework where each cell follows the same resource allocation methodology (based on cell index, frequency location, and timing), the system achieves high resource efficiency while minimizing the complexity of configuration management through standardized, repeatable patterns rather than entirely custom configurations for each cell.
Data Source
AI summary
Disclosed in the present application is a method by which a terminal transmits and receives a signal. Particularly, the method comprises the steps of: receiving a downlink signal from a plurality of cells; transmitting, to a serving cell among the plurality of cells, an acknowledgement/negative ACK (ACK/NACK) response for the downlink signal; and receiving, from at least one cell among the plurality of cells, retransmission for the downlink signal.