Multi-Beam UE Message 1 Transmission Power Ramping
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Solution Overview
Problem
In 3GPP NR, the power ramping scheme for retransmitting Message 1 (Msg. 1) in a multi-beam system is challenging due to time delays and interference, with various methods complicating the determination of optimal power levels and beam switching strategies for user equipment (UE).
Innovation Solution
A method for transmitting and retransmitting Msg. 1 through multiple beams based on power ramping, where the UE switches between beams with increasing power levels, stopping retransmissions upon successful receipt of Msg. 2, and adjusting power levels to ensure maximum transmission power is reached within a subset of beams, minimizing beam switching and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power ramping is applied for Msg. 1 retransmission through multiple beams, then transmission reliability is improved, but time delay increases due to multiple retransmissions
Solution Approach 1:
The patent applies dynamics by making the power level and beam selection adaptive rather than static. The UE dynamically adjusts the power level based on the beam index, using different power levels for different beams in the beam set. This dynamic adjustment allows the system to achieve reliable transmission without requiring exhaustive retransmissions across all beams, thereby reducing time delay while maintaining transmission reliability.
2Reliability
If multiple beams are used for Msg. 1 transmission, then transmission reliability is improved, but interference with other UEs increases
Solution Approach 1:
The patent applies local quality by assigning different power levels to different beams based on their specific characteristics and indices. Instead of using uniform power across all beams, the system tailors the power level locally to each beam's requirements. This localized power adjustment improves transmission reliability for each specific beam while reducing overall interference to other UEs by avoiding excessive power transmission on all beams simultaneously.
3Reliability
If beam switching is performed for retransmission, then transmission reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the beam selection process into manageable segments. The UE maintains a beam set with assigned power levels for different beams, and the base station provides feedback indicating which beam(s) achieved successful reception. This segmented approach allows the UE to perform targeted beam switching only when necessary, rather than continuously switching through all possible beams, thereby reducing device complexity while maintaining transmission reliability.
4Reliability
If power level is increased for retransmission, then transmission reliability is improved, but energy consumption increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the power level parameter based on the beam index and transmission requirements. The UE uses different power levels for different beams rather than maintaining a constant high power level for all transmissions. This parameter adjustment ensures that power is increased only when and where necessary to achieve reliable transmission, thereby reducing overall energy consumption while maintaining transmission reliability.
Data Source
AI summary
A method and user equipment for transmitting a message of a random access procedure in a multi-beam system includes: transmitting and retransmitting a message 1 of the RA procedure through a first beam of a plurality of transmission beams of the UE based on power ramping; and retransmitting, if one or more Msg. 2 (RAR) is not successfully received corresponding to the message 1 transmission/retransmission, the message 1 through a second beam of the plurality of transmission beams after switching the first beam to the second beam at a second power level which is the same as or higher than a first power level of the first beam.