Uplink PRACH Repetition for Reliable Random Access at High Path Loss
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Solution Overview
Problem
Next-generation wireless communication systems face challenges in maintaining adequate uplink transmission success rates, particularly at higher frequencies, due to increased path loss and potential radio access failures, which can reduce effective cell coverage.
Innovation Solution
Implementing Multiple-PRACH (MP) transmissions, where a user equipment (UE) transmits a random access preamble multiple times before monitoring for a response, and adjusts PRACH resources based on downlink reference signal received power (RSRP) and configured thresholds, to enhance uplink transmission success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single PRACH transmission is used, then device complexity is reduced, but uplink transmission success rate deteriorates due to increased path loss at higher frequencies
Solution Approach 1:
The UE transmits the RA preamble multiple times in advance before monitoring for RAR, increasing the probability that at least one transmission will be successfully received by the base station despite path loss conditions
Solution Approach 2:
The MP transmissions are performed periodically with a determined number of repetitions, creating a structured pattern of repeated transmissions that improves reliability without requiring continuous transmission
2Area of stationary object
If multiple PRACH transmissions are performed, then effective cell coverage is increased, but loss of time increases due to extended monitoring window
Solution Approach 1:
Multiple transmissions are completed beforehand, ensuring that the base station receives at least one preamble within the extended window, thereby expanding effective coverage to UEs with higher path loss
Solution Approach 2:
The RAR monitoring window duration is dynamically adjusted based on the number of MP transmissions configured, allowing the system to adapt the time parameter to match the transmission repetition count
3Reliability
If multiple PRACH transmissions are performed, then uplink transmission reliability is improved, but use of energy increases
Solution Approach 1:
The system performs a determined number of transmissions that is sufficient to achieve the required reliability threshold, avoiding unnecessary excessive transmissions that would waste energy
Solution Approach 2:
The number of MP transmissions is configured as a adjustable parameter that can be optimized based on channel conditions and reliability requirements, allowing energy consumption to be adapted to actual needs
Data Source
AI summary
A method and a User Equipment (UE) for performing uplink transmissions and a related base station (BS) are provided. The method includes a UE receiving a Physical Random Access Channel (PRACH) configuration indicating a plurality of parameters and a first set of PRACH resources from a base station, each of the plurality of parameters corresponding to a respective one of the first set of PRACH resources; initiating a Random Access (RA) procedure; selecting a first PRACH resource from the first set of PRACH resources to transmit an RA preamble for the RA procedure, the first PRACH resource corresponding to a first parameter of the plurality of parameters; and performing Multiple-PRACH (MP) transmissions on the first PRACH resource. The first set of PRACH resources is configured for the MP transmissions and the first number of times is determined by the first parameter.