PRACH Configuration for Timing Advance in Additional PCI Uplinks
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Solution Overview
Problem
In wireless communications systems, determining a timing advance (TA) for uplink transmissions associated with a PCI different from the serving cell is unclear, as PRACH transmissions are typically not supported in non-serving cells, hindering efficient synchronization and system performance.
Innovation Solution
A method for a user equipment (UE) to receive an order to trigger a PRACH transmission for an additional PCI, transmit a PRACH, and then receive an indication of a TA value for the uplink transmission associated with that additional PCI, enabling synchronization with non-serving cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PRACH transmissions are not supported in non-serving cells, then the system maintains simpler synchronization mechanisms, but the UE cannot obtain TA values for additional PCIs, hindering synchronization with non-serving cells
Solution Approach 1:
The network entity pre-configures the UE with multiple PRACH configurations associated with different PCIs before the UE needs to synchronize with non-serving cells. This preliminary configuration enables the UE to immediately perform PRACH transmissions for TA acquisition when needed, without requiring complex on-demand configuration procedures.
Solution Approach 2:
The PRACH configuration mechanism is extended to serve multiple functions: it not only supports random access procedures but also enables TA value acquisition for synchronization with non-serving cells. The same PRACH infrastructure is utilized for both traditional random access and the new synchronization purpose, avoiding the need for separate dedicated mechanisms.
2Productivity
If the UE transmits PRACH for additional PCI, then the UE can obtain TA value for faster synchronization, but the system requires multiple PRACH configurations to be managed
Solution Approach 1:
The PRACH configuration is segmented into multiple independent configurations, each associated with a specific PCI. This segmentation allows the UE to select and apply the appropriate configuration based on the target PCI, enabling efficient TA acquisition for multiple non-serving cells while maintaining clear organization and manageability of configurations.
Solution Approach 2:
The network entity acts as an intermediary by providing clear signaling that indicates which PRACH configuration should be used for each additional PCI. This intermediary signaling mechanism simplifies the UE's decision-making process, allowing the UE to automatically select the correct configuration without complex evaluation logic.
3Reliability
If TA indication is provided for additional PCI, then uplink transmission synchronization is improved, but the signaling overhead increases
Solution Approach 1:
The TA indication for additional PCI is merged with existing random access response messaging structures. Instead of creating separate dedicated signaling messages for TA transmission, the TA values are incorporated into the existing RAR framework, thereby improving uplink synchronization while minimizing additional signaling overhead.
Data Source
AI summary
Certain aspects of the present disclosure provide a method for wireless communication by a user equipment (UE) generally including receiving signaling indicating a set of physical random access channel (PRACH) configurations, receiving, a physical downlink control channel (PDCCH) order to trigger a PRACH transmission associated with an additional PCI different from a first PCI associated with a serving cell, transmitting a PRACH associated with the additional PCI based on one PRACH configuration of the set of PRACH configurations that is associated with the additional PCI, receiving an indication of a timing advance (TA) associated with the additional PCI, and applying the TA for an uplink transmission associated with the additional PCI.