Joint HARQ-ACK Codebook for Multicast Unicast Feedback
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Solution Overview
Problem
Current wireless communication systems, such as 5G New Radio (NR), lack an efficient method for designing Hybrid Automatic Repeat Request (HARQ) feedback codebooks that can jointly handle multicast and unicast traffic, leading to low spectrum efficiency due to the absence of user equipment (UE) feedback in multicast scenarios.
Innovation Solution
The proposed solution involves constructing a joint HARQ-ACK codebook by combining the downlink data to uplink feedback timing sets for both multicast and unicast traffic. This codebook determines the number of downlink slots and feedback bits based on the union of the timing sets and the intersection of Time Domain Resource Allocation (TDRA) lists for multicast and unicast configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate HARQ feedback mechanisms are used for multicast and unicast, then reliability is maintained for both traffic types, but device complexity and signaling overhead increase
Solution Approach 1:
The patent merges multicast and unicast HARQ feedback into a single joint codebook structure. The codebook combines feedback bits for both traffic types, using a unified construction method that determines the number of feedback bits based on the union of TDRA lists from both multicast and unicast configurations, thereby reducing overall system complexity while maintaining separate feedback reliability.
Solution Approach 2:
The joint codebook serves multiple functions simultaneously: it provides HARQ feedback for both multicast and unicast traffic within a single structure. The codebook is designed to be universal, accommodating different traffic types with different reliability requirements through a unified framework that adapts to both scenarios.
2Productivity
If HARQ feedback for multicast is enabled, then spectrum efficiency improves, but signaling overhead increases when combined with unicast feedback in the same uplink slot
Solution Approach 1:
The patent combines multicast and unicast HARQ feedback into a single uplink transmission using a joint codebook. By merging the feedback mechanisms, the system enables multicast HARQ functionality (improving spectrum efficiency) while reducing the total signaling overhead compared to separate feedback transmissions, as both feedback types share the same uplink resources and codebook structure.
3Quantity of substance
If a joint HARQ codebook is used for multicast and unicast, then signaling overhead is reduced, but the complexity of codebook construction and feedback timing increases
Solution Approach 1:
The patent segments the codebook construction process into distinct phases: determining the union of TDRA lists to establish codebook size, allocating specific feedback bits for multicast versus unicast based on intersection analysis, and structuring the feedback timing separately for each traffic type. This segmentation manages construction complexity by breaking down the joint codebook creation into systematic steps.
Solution Approach 2:
The codebook construction employs dynamic parameters including flexible feedback timing indicators (K1 values) that can be independently configured for multicast and unicast, and adaptive bit allocation that adjusts based on the intersection of TDRA lists. This dynamic approach allows the system to optimize codebook structure for different traffic patterns while managing construction complexity through standardized procedures.
Data Source
AI summary
A wireless device (110) obtains a codebook that is based on a first downlink data to uplink feedback timing set (30) for feedback associated with multicast downlink data and a second downlink data to uplink feedback timing set (31) for feedback associated with unicast downlink data. A number of downlink slots associated with the codebook is determined based on a union of the first set and the second set. The wireless device transmits feedback to a network node (160) based on the codebook. A number of feedback bits (32) in the codebook for a downlink slot associated with the codebook is determined based on a union of a first Time Domain Resource Allocation, TDRA, list and a second TDRA list. The first list indicates possible allocations of symbols for a downlink shared channel for multicast. The second list indicates possible allocations of symbols for a downlink shared channel for unicast.