Random Access Preamble Power Control for Multi-Preamble NR Uplink
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Solution Overview
Problem
In the new radio (NR) system, determining the transmit power of multiple random access preambles before receiving a random access response (RAR) is a challenge, as existing methods are inadequate for scenarios where multiple preambles are sent on the same or different random access channel occasions.
Innovation Solution
A power determining method that calculates the transmit power of multiple random access preambles based on the quantity of preambles, path loss, and power offset, considering factors such as preamble power ramping steps and differences between two-step and four-step random access, to improve random access performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device sends multiple random access preambles before receiving RAR, then the random access success rate is improved, but the transmit power determination becomes complex and uncertain
Solution Approach 1:
The patent applies parameter changes by introducing a quantity-based power offset Δ(N) that adjusts the transmit power based on the number of preambles N sent. The formula PPRACH,b,f,c(i)=min{PCMAX,f,c(i), PPRACH,target,f,c+Δ(N)+PLb,f,c} dynamically modifies the power parameters according to the preamble quantity, resolving the power determination complexity while maintaining success rate improvement
Solution Approach 2:
The patent implements dynamics by making the transmit power adaptive rather than static. The power offset Δ(N) dynamically adjusts based on the actual number of preambles transmitted, allowing the system to optimize power usage in real-time according to the random access scenario, thereby simplifying power determination while supporting multiple preamble transmissions
2Reliability
If the terminal device sends multiple random access preambles on the same or different ROs, then the coverage and reliability are improved, but the interference to the network increases
Solution Approach 1:
The patent uses parameter changes to control interference by adjusting the transmit power offset Δ(N) based on the number of preambles. This ensures that power increases only when necessary for reliability, preventing excessive interference. The power is optimized to be just sufficient for the required number of preamble transmissions, balancing reliability improvement with interference control
Data Source
AI summary
Embodiments of this application provide a power determining method, an apparatus, and a system, to resolve a problem of how to determine transmit power of sending a plurality of random access preambles. The method includes: determining first transmit power of N random access preambles to be sent to a network device, where the first transmit power is related to a quantity N of the random access preambles, and N is an integer greater than 1; and sending the N random access preambles to the network device at the first transmit power. This application is applicable to the field of communication technologies.