Multi-TRP PDCCH Transmission for URLLC Reliability
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Solution Overview
Problem
Current wireless communication technologies face challenges in achieving reliable and robust downlink control channel transmissions, particularly in ultra-reliable and low-latency scenarios, where traditional methods lack sufficient diversity and reliability.
Innovation Solution
The implementation of multi-Transmission Reception Points (TRP) transmission for Physical Downlink Control Channel (PDCCH) with multiple repetitions, configured through Transmission Configuration Indicator (TCI) states and repetition levels, allowing for spatial diversity across different TRPs and transmission domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional single-TRP PDCCH transmission is used, then device complexity is low, but reliability is insufficient for ultra-reliable low-latency communications
Solution Approach 1:
The PDCCH transmission is segmented across multiple TRPs, where each TRP transmits a portion of the control channel information. This segmentation enables spatial diversity, improving reliability by ensuring that if one TRP's transmission is blocked or degraded, other TRPs can still deliver the control information to the UE.
Solution Approach 2:
The patent introduces spatial dimension diversity by utilizing multiple TRPs located at different physical positions. This transitions from a single-point transmission model to a multi-point spatial distribution model, adding the spatial dimension as a new degree of freedom for achieving reliable control channel delivery in challenging radio conditions.
2Reliability
If multiple repetitions of PDCCH are transmitted from the same TRP, then reliability improves through time diversity, but spatial diversity is limited
Solution Approach 1:
The patent merges time diversity and spatial diversity by combining multiple transmission repetitions across different time instances with multiple TRPs transmitting simultaneously or in a coordinated manner. This unified approach allows the system to benefit from both temporal redundancy (through repetitions) and spatial redundancy (through multiple TRPs), providing enhanced reliability and adaptability.
Solution Approach 2:
By introducing multiple spatial dimensions through multiple TRPs, the patent transforms the transmission system from a single-spatial-point model to a multi-spatial-point model. This enables the system to achieve spatial diversity while maintaining time diversity through repetitions, thereby improving both reliability and adaptability to varying channel conditions.
3Reliability
If multi-TRP transmission with multiple TCI states is implemented, then spatial diversity and reliability are enhanced, but configuration and management complexity increases
Solution Approach 1:
The network configures and activates multiple TCI states in advance through RRC signaling and MAC CE commands before actual PDCCH transmission. This preliminary configuration allows the UE to have the necessary spatial filter information ready, reducing the complexity of real-time state management during transmission and enabling faster adaptation to changing channel conditions.
Solution Approach 2:
The patent implements dynamic TCI state selection and activation mechanisms where the network can flexibly activate or deactivate specific TCI states based on current channel conditions, UE location, and traffic requirements. This dynamic management approach optimizes the balance between reliability enhancement through multiple TCI states and the complexity of managing these states, allowing the system to adapt to varying operational scenarios.
Data Source
AI summary
Embodiments disclosed herein can enable multi-TRP transmission for PDCCH to achieve diversity gain for the potential benefits to URLLC use cases with challenging reliability/robustness requirements. Specifically, multi-TRP transmission for PDCCH can be performed at different levels as follows: 1. PDCCH with multi-TRP transmission on repetition level; 2. PDCCH with multi-TRP transmission on CCE level; and/or 3. PDCCH with multi-TRP transmission on REGB level.