PDCCH-Ordered PRACH Power Ramping for LTM Handover
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Solution Overview
Problem
Current 3GPP specifications do not provide clear guidelines for power ramping procedures during PDCCH ordered PRACH transmissions in lower-layer triggered mobility (LTM), leading to uncertainties in transmission power determination and potential synchronization errors during handovers between network cells.
Innovation Solution
The method involves setting the RA preamble power ramping counter to an initial value for initial PRACH transmissions and incrementing it for retransmissions based on PDCCH orders, with defined maximum values and power ramping steps, and managing power ramping counters to handle scenarios where RAR is not configured.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power ramping procedure is implemented for PDCCH ordered PRACH transmission, then transmission reliability is improved, but device complexity increases due to counter management
Solution Approach 1:
The patent changes the state of the power ramping counter based on PDCCH order reception. When a PDCCH order is received, the counter is reset to initial value, and when PRACH transmission occurs without PDCCH order, the counter is incremented. This parameter change mechanism ensures reliable power ramping while maintaining manageable complexity through clear state transitions.
Solution Approach 2:
The patent implements a feedback mechanism where the UE monitors for PDCCH orders and adjusts power ramping counter behavior accordingly. The counter value feeds back into subsequent PRACH transmission power decisions, creating a closed-loop system that improves reliability while keeping the control logic manageable through defined feedback conditions.
2Measurement precision
If power ramping counter is incremented for each PRACH retransmission, then synchronization accuracy is improved, but loss of time increases due to additional processing
Solution Approach 1:
The patent performs preliminary actions by pre-defining the power ramping counter behavior based on whether a PDCCH order is received. The counter is reset in advance when PDCCH order is detected, and the increment operation is prepared for when PRACH transmission occurs. This preliminary setup reduces real-time processing complexity and time loss during actual transmissions.
3Manufacturing precision
If clear power ramping guidelines are provided in specifications, then manufacturing precision is improved, but adaptability decreases due to rigid protocol requirements
Solution Approach 1:
The patent introduces dynamic behavior into the power ramping procedure through conditional counter management. The counter can be reset or incremented based on dynamic reception of PDCCH orders, allowing the system to adapt to different transmission scenarios while maintaining precise control through well-defined conditional logic. This dynamic approach balances implementation precision with protocol adaptability.
Data Source
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AI summary
Embodiments of the present disclosure provide a method for improved physical downlink control channel (PDCCH) ordered physical random-access channel (PRACH) transmission in lower-layer triggered mobility (LTM). The method includes receiving a PDCCH order to initiate a PRACH transmission to at least one cell. The method also includes decoding a PRACH transmission index value, where the PRACH transmission index value describes whether the PRACH transmission is an initial transmission or a retransmission, and where the PRACH transmission index value is associated with a target downlink (DL) reference signal (RS). The method also includes determining a random access (RA) preamble power ramping counter value. The method also includes transmitting, based in part on a PRACH transmission power level, the PRACH transmission to the at least one cell, where the PRACH transmission power level is determined based in part on the RA preamble power ramping counter value.