PDSCH Repetitions and HARQ-ACK Feedback in Multi-TRP 5G
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Solution Overview
Problem
The increasing complexity in 5G networks due to multiplexing with multiple transmission/reception points (TRPs) poses challenges in efficient HARQ-ACK feedback multiplexing, PUCCH resource determination, and time-domain resource allocation for PDSCH repetitions, particularly in scenarios where ambiguity arises between Downlink Control Information (DCIS) and differing TRP-ids.
Innovation Solution
Implementing a method where HARQ-ACK bits for TRP-0 and TRP-1 are concatenated based on increasing TRP indices, using pseudo-codes for semi-static codebooks, and applying Downlink Assignment Index (DAI) per TRP for joint feedback, along with dynamic SLIV sequence design for time-domain resource allocation, allowing for flexible and low-latency PDSCH repetitions across multiple TRPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ-ACK feedback is multiplexed across multiple TRPs, then feedback coverage is improved, but ambiguity arises between DCIs from different TRPs
Solution Approach 1:
The patent segments the HARQ-ACK feedback process by introducing TRP-specific Downlink Assignment Indices (DAIs) that uniquely identify each TRP's DCI. This segmentation allows the UE to distinguish between DCIs from different TRPs while maintaining multiplexed feedback, thereby improving coverage without introducing ambiguity.
2Adaptability or versatility
If PUCCH resources are allocated for multiple TRPs, then feedback capability is improved, but resource determination complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring PUCCH resource sets and associating them with specific TRP indices before actual feedback transmission. This allows the UE to determine PUCCH resources based on pre-established rules rather than complex real-time calculations, reducing determination complexity while maintaining multi-TRP capability.
3Reliability
If time-domain resources are allocated for PDSCH repetitions across TRPs, then transmission reliability is improved, but resource allocation flexibility is reduced
Solution Approach 1:
The patent introduces dynamic SLIV (Start and Length Indicator Value) sequences that can be flexibly configured for different TRPs and transmission scenarios. This dynamic resource allocation mechanism allows the system to adapt time-domain resources for PDSCH repetitions based on actual channel conditions and TRP availability, maintaining both reliability and flexibility.
Data Source
AI summary
Systems and methods for transmission of PDSCH and HARQ-ACK feedback in 5G networks are described. The TDRA of PDSCH repetitions are indicated in a DCI by a SLIV sequence configuration that contains multiple SLIV sequences. Each SLIV sequence for a slot is associated with an independent repetition factor and may also be associated with a partition factor to indicate a partition within the slot. One or more TRPs may be used to transmit each PDSCH repetition. The TCI states are mapped to the PDSCH repetitions in a round-robin fashion using an offset in terms of number of PDSCH repetitions from where TCI state switching starts and a number of consecutive PDSCH repetitions per TCI state. The HARQ-ACK bits in response to the PDSCH from the TRPs are concatenated in order of increasing control resource set higher layer signaling index.