Default Path Loss Reference Signal Selection in 5G Wireless Networks
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Solution Overview
Problem
In wireless communication systems, particularly in 5G and LTE networks, there is a challenge in selecting a default path loss reference signal (PLRS) and spatial relation for user equipment (UE) when no explicit indication is provided by the base station, leading to potential inaccuracies in beam selection and resource allocation due to the absence of control resource sets (CORESETs) in active downlink bandwidth parts (BWP).
Innovation Solution
The method involves selecting a default PLRS and spatial relation based on the active physical downlink shared channel (PDSCH) transmission configuration indicator (TCI) state of the active DL BWP, allowing UE to receive or transmit using a default PLRS and spatial relation, even without explicit signaling from the base station, thereby ensuring consistent communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the base station does not provide explicit indication of PLRS or CORESET in active DL BWP, then signaling resources are conserved, but the UE cannot accurately determine the default PLRS leading to potential communication failures
Solution Approach 1:
The UE autonomously determines the default PLRS by selecting from available RS resources based on pre-configured criteria (TCI states, QCL types) without requiring explicit base station indication. This self-service mechanism allows the UE to independently resolve the PLRS selection problem while conserving signaling resources.
Solution Approach 2:
The system pre-configures multiple RS resources with different QCL types and TCI states before communication begins. When explicit PLRS indication is absent, the UE can immediately refer to these pre-configured options to determine the appropriate default PLRS, eliminating the need for real-time base station signaling.
2Measurement precision
If the UE selects default PLRS based on TCI state of active DL BWP, then path loss measurement accuracy is improved, but device complexity increases due to additional selection logic
Solution Approach 1:
The TCI state configuration serves multiple functions: it defines downlink beam directionality, provides QCL information for channel estimation, and simultaneously serves as the basis for default PLRS selection. This multi-functionality reduces the need for separate dedicated PLRS configuration mechanisms.
Solution Approach 2:
The UE dynamically adjusts its PLRS selection parameters based on the active DL BWP's TCI state. By changing the selection criteria according to the current operational state (TCI state, QCL type), the UE achieves accurate path loss measurement without requiring complex hardwired logic for every possible scenario.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may select, as a default path loss reference signal (PLRS), a reference signal (RS) resource that corresponds to an active physical downlink shared channel (PDSCH) transmission configuration indicator (TCI) state of an active downlink (DL) bandwidth part (BWP) if a control resource set (CORESET) is not provided in the active DL BWP. The UE may receive the default PLRS. In some aspects, the UE may select, as a default spatial relation for a physical uplink control channel (PUCCH) communication, a spatial relation that corresponds to an active PDSCH TCI state of an active DL BWP if a CORESET is not provided in the active DL BWP. The UE may receive the PUCCH communication using a TCI state that corresponds to the default spatial relation. Numerous other aspects are described.