PRACH Power Control Using Multi-Level Initial Access Signals
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Solution Overview
Problem
In wireless communication systems, UEs face challenges in determining accurate initial transmit power levels for PRACH signaling due to discrepancies between downlink and uplink path losses, especially when using multiple component carriers or flexible duplex communications, leading to increased association delays and power consumption.
Innovation Solution
UEs transmit multiple PRACH signals at different power levels, and the network entity responds with a message indicating detected signals, allowing the UE to determine an appropriate power level for subsequent transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE uses open loop power control based on DL path loss to determine initial UL power level, then the UE can select an initial TX power level without UL channel information, but the selected power level may be insufficient when DL and UL channels are not similar (e.g., in FDD band or with SUL carrier)
Solution Approach 1:
The UE transmits multiple PRACH signals at different power levels before the association process is complete. This preliminary action allows the network to detect which power level was sufficient, enabling the UE to determine the correct initial power level for subsequent communications without waiting for channel establishment.
Solution Approach 2:
The network entity provides feedback by detecting which PRACH signals were received and including this information in the response message. This feedback mechanism allows the UE to learn the actual UL path loss conditions and adjust its power level selection accordingly, resolving the accuracy issue in initial power level determination.
2Productivity
If the UE transmits PRACH signaling at insufficient power level due to inaccurate path loss estimation, then the association process can start, but the network entity cannot detect the signaling, requiring retransmission after monitoring period
Solution Approach 1:
The UE performs multiple PRACH transmissions at different power levels as a preliminary step before the formal association process begins. This allows the network to detect the signaling in the first attempt, eliminating the need to wait for the monitoring period to expire and avoiding retransmission delays.
Solution Approach 2:
The UE creates multiple copies of the PRACH signaling at different power levels and transmits them simultaneously. This copying approach ensures that at least one version of the signaling reaches the network entity with sufficient power, guaranteeing detection without requiring sequential retransmissions.
3Reliability
If the UE waits for the monitoring period to expire before retransmitting PRACH signaling at higher power level, then the network can properly monitor for responses, but the association process duration is significantly increased
Solution Approach 1:
The UE transmits multiple PRACH signals at different power levels as a preliminary action before the association process is complete. This allows the network to detect the signaling immediately without requiring the UE to wait for the monitoring period to expire, significantly reducing the association process duration while maintaining detection reliability.
Solution Approach 2:
The UE continuously transmits PRACH signals at multiple power levels without interruption until the network detects and responds to the signaling. This continuous action eliminates the idle waiting period that would otherwise occur after the monitoring period expires, keeping the association process moving efficiently.
Data Source
AI summary
This disclosure provides systems, methods, and apparatuses, including computer programs encoded on computer storage media, for wireless communication. Various aspects relate to initial physical random access channel (PRACH) power control using multiple PRACH signals, and more particularly to supporting one or more initialization and power control operations between a user equipment (UE) and a network entity prior to an association process. The initial PRACH power control may include the UE transmitting, to the network entity, a first set of PRACH signals at different respective power levels. The network entity may transmit a response message indicating a single set of PRACH signals detected by the network entity, and the UE may detect whether a first PRACH signal, of the first set of PRACH signals, is included in the single set of PRACH signals to select a power level associated with the first PRACH signal for transmitting association messages.