Multi-TRP Capability Indication for Mobile-Terminated EDT Reliability
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Solution Overview
Problem
In mobile-terminated early data transmission (EDT) for 5G wireless systems, signal blockage causes reliability and latency issues due to sudden signal strength drops, particularly in mmWave deployments, leading to delays in data delivery when random access responses are not received within the RAR window or when data is blocked during transmission.
Innovation Solution
The method involves user equipment (UE) indicating its capability to receive multi-transmit receive point (TRP) transmissions during the random access procedure, allowing the network to allocate resources for additional beams, thereby improving signal reliability and latency by scheduling data transmission on multiple beams if signal blockage occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-beam transmission is used in mobile-terminated EDT, then device complexity and signaling overhead are reduced, but reliability deteriorates due to signal blockage causing sudden signal strength drops
Solution Approach 1:
The UE indicates its capability to receive multi-TRP transmission in advance during the random access procedure (in Msg1 or via RACH capability indication). This preliminary action allows the network to prepare and allocate resources for additional beams before actual data transmission occurs, enabling rapid response to signal blockage without increasing overall system complexity
Solution Approach 2:
The transmission path is segmented into multiple independent beams from different TRPs. Instead of relying on a single transmission path, the system divides the data transmission into parallel paths through multiple beams, allowing selective use of alternative paths when signal blockage occurs on one beam, thereby improving reliability without requiring complex end-to-end retransmission protocols
2Reliability
If additional beams are allocated for multi-TRP transmission, then reliability improves by providing alternative paths, but signaling overhead and processing complexity increase
Solution Approach 1:
The capability indication mechanism serves multiple functions: it informs the network of UE multi-TRP reception capability, triggers resource allocation for additional beams, and enables the network to optimize beam selection based on UE capability. This multi-functionality reduces the need for separate signaling messages, thereby minimizing signaling overhead while maintaining reliability improvements
Solution Approach 2:
The system changes the state parameter of beam allocation from static single-beam to dynamic multi-beam based on UE capability indication. By modifying this parameter, the network can allocate additional beams only when needed (when UE indicates capability), avoiding unnecessary resource allocation and signaling overhead for UEs that do not require or support multi-TRP transmission
3Loss of time
If multi-TRP transmission is implemented, then latency is reduced by providing alternative transmission paths, but device complexity and network processing requirements increase
Solution Approach 1:
The UE autonomously indicates its multi-TRP reception capability during the random access procedure without requiring network configuration or manual setup. This self-service approach allows the network to automatically activate multi-beam transmission when capability is indicated, reducing network processing complexity and enabling rapid latency reduction without complex coordination procedures
Data Source
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AI summary
Systems, methods, apparatuses, and computer program products for improving reliability of mobile-terminated (MT) early data transmission (EDT). The method can include receiving, from a primary transmit receive point (TRP), a message. The method may include transmitting, to the primary TRP, an indication of a capability to receive a multi-TRP transmission of a message 4 of a random access procedure. The indication may be a physical random access channel (PRACH) preamble.