MAC Handling for mTRP Inter-DU Mobility With HARQ Segmentation
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Solution Overview
Problem
Current wireless communication technologies inadequately enable inter-DU, intra-CU mobility of UEs, limiting mobility scenarios due to challenges in integrating the MAC layer with different DUs and HARQ entities, especially in non-co-located scenarios.
Innovation Solution
Implementing a MAC handling mechanism that configures DUs with the same HARQ entity and assigns different HARQ processes, enabling UEs to communicate with multiple DUs within the same CU by associating HARQ processes with TRP IDs, and optionally using dual-MAC or dual-RLC architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single HARQ entity is used across multiple DUs, then mobility management is simplified, but HARQ process conflicts and interference occur between non-co-located DUs
Solution Approach 1:
The patent segments the HARQ processes into different sets associated with different TRP IDs. Each TRP has its own set of HARQ processes, preventing conflicts between non-co-located DUs while maintaining a unified MAC layer structure. This segmentation allows independent HARQ management per TRP without requiring separate MAC entities.
Solution Approach 2:
The patent introduces TRP ID as an intermediary identifier that distinguishes HARQ processes across different TRPs. The MAC layer uses TRP ID to route and manage HARQ processes, acting as a mediator between the unified MAC structure and the need for TRP-specific HARQ management.
2Reliability
If separate MAC entities are implemented for each DU, then HARQ process conflicts are eliminated, but device complexity and overhead increase
Solution Approach 1:
The patent implements a universal MAC layer that serves multiple TRPs simultaneously. The MAC entity is designed to handle HARQ processes from different TRPs by using TRP ID as a distinguishing parameter, eliminating the need for separate MAC entities while maintaining proper HARQ isolation and management.
3Productivity
If HARQ processes are shared across DUs with different PCIs and TAs, then resource utilization is optimized, but timing alignment and synchronization issues arise
Solution Approach 1:
The patent segments HARQ processes by TRP ID, creating distinct HARQ process sets for each TRP. This segmentation maintains synchronization stability for each TRP while allowing efficient resource utilization across the network, as each TRP manages its own HARQ processes independently.
Data Source
AI summary
Techniques, described herein, include solutions for handling multiple transmission and reception points (mTRPs) for inter-distributed unit (DU), intra-centralized unit (CU) mobility of user equipment (UE). DUs may each implement a media access control (MAC) layer, and a CU may add a new DU by configuring the DU to implement an instance of a hybrid automatic repeat request (HARQ) entity operating on an existing DU. HARQ processes associated with each DU may be the same or different and the UE may be configured accordingly. The UE may use the same MAC entity to communicate with each DU. In some implementations, HARQ entities of DUs may be associated with mTRP IDs. Alternatively, a new MAC and/or RLC layer may be implemented in the new DU and the UE may be configured accordingly. RLC layers may be radio bearer (RB) or logical channel specific.