Inter-Transport Block Time Interleaving in Wireless MBS
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Solution Overview
Problem
Existing wireless communication systems struggle to efficiently interleave multiple instances of transport blocks (TBs) in multicast and broadcast services, leading to challenges in soft combining and increased system latency.
Innovation Solution
The network entity transmits downlink control information (DCI) messages that schedule multiple instances of TBs, allowing for time-interleaved transmission. This includes using DCI formats that include TB indicators such as Hybrid PDCCH Indicators (HPIDs) and New Data Indicators (NDIs), enabling user equipment (UE) to perform soft combining of interleaved TB instances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple instances of TBs are time-interleaved for multicast/broadcast services, then spectral efficiency and resource utilization are improved, but soft combining capability is lost and system latency increases
Solution Approach 1:
The patent segments the TB scheduling into separate DCI formats: Type 1 DCI for scheduling TB instances and Type 2 DCI for indicating soft combining requirements. This segmentation allows the system to maintain time-interleaving benefits while separately managing soft combining capabilities through dedicated control information.
Solution Approach 2:
The patent introduces an intermediary mechanism using DCI format 2 as a mediator between the time-interleaved TB instances and the UE's soft combining process. This intermediary carries control information that enables UEs to properly identify and combine interleaved TB instances, resolving the conflict between spectral efficiency and soft combining capability.
2Adaptability or versatility
If multiple instances of TBs are time-interleaved, then resource allocation flexibility is improved, but processing complexity at UE increases
Solution Approach 1:
The patent applies local quality by providing different levels of control information to different UEs based on their capabilities. Advanced UEs receive detailed DCI format 2 information enabling soft combining, while legacy UEs receive simplified scheduling information. This localized adaptation maintains resource allocation flexibility without uniformly increasing processing complexity across all UEs.
3Loss of time
If time-interleaved TB instances are transmitted, then system latency is reduced through faster resource utilization, but HARQ feedback timing becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-configuring HARQ feedback timing parameters in the DCI format 2 before the actual TB transmission. This allows the UE to anticipate and properly time its HARQ feedback responses for time-interleaved TB instances, reducing system latency while managing feedback timing complexity through advance parameter provision.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A network entity may transmit DCIs to a UE to schedule instances of one or more MBS TBs, the multiple instances of the one or more TBs being time-interleaved. For example, the network entity may transmit a first set of DCIs scheduling a first set of instances of a first TB, and a second set of DCIs scheduling a second set of instances of a second TB, where at least one instance of the first set of instances may be interleaved with the second set of instances. In some cases, the first and second set of DCIs may include one DCI to schedule the respective set of instances, or one DCI per instance of the respective set of instances. Additionally, or alternatively, the network entity may indicate one or more parameters to the UE associated with MBS inter-TB time interleaving.