Random Access Preamble Diversity for Uplink Coverage
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Solution Overview
Problem
Existing random access procedures in wireless communication systems, such as NR, face challenges due to lack of early beam information and support for repetitions, leading to potential coverage performance bottlenecks in channels like Msg1 preamble, Msg3 PUSCH, and MsgA PUSCH.
Innovation Solution
The proposed method involves transmitting multiple preambles on different transmission chains of the terminal device, associated with the same or different synchronization signals and physical broadcast channel blocks, and employing techniques like closed-loop and open-loop transmit diversity, frequency and spatial domain repetitions, and beam refinement using SSB and CSI-RS signals to enhance coverage and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single preamble is transmitted on one transmission chain, then the device complexity is low, but the uplink channel coverage is insufficient
Solution Approach 1:
The patent segments the preamble transmission by dividing it into multiple preambles transmitted on different transmission chains. Each transmission chain independently transmits a preamble, creating multiple copies that can be received and combined at the base station. This segmentation improves uplink coverage by providing diversity against fading and interference while maintaining manageable device complexity through standardized transmission procedures for each chain.
Solution Approach 2:
The patent merges the transmissions from multiple transmission chains by having the base station combine the received preambles from different chains. This combining process at the receiver side consolidates the signal energy and diversity gains from multiple transmission paths, improving overall detection reliability and uplink coverage without requiring complex processing at the UE side.
2Reliability
If multiple preambles are transmitted on different transmission chains, then the uplink channel coverage is improved, but the resource consumption increases
Solution Approach 1:
The patent applies dynamics by enabling flexible configuration of the number of preambles transmitted on different transmission chains. The system can adapt the transmission strategy based on channel conditions, UE capabilities, and network requirements. This dynamic approach allows the system to optimize between reliability improvement and resource consumption by adjusting the number of active transmission chains and preambles per chain according to actual needs.
Solution Approach 2:
The patent changes key parameters such as the number of transmission chains, the number of preambles per chain, and the power allocation across chains. These parameter adjustments allow the system to scale the preamble transmission strategy to match channel conditions and resource availability, improving detection reliability when needed while conserving resources when channel conditions are good or resources are limited.
3Measurement precision
If timing advance functionality is implemented, then the PUSCH reception timing accuracy is improved, but the random access procedure steps increase
Solution Approach 1:
The patent implements timing advance functionality as a preliminary action during the random access procedure. The base station measures the timing of received preambles from multiple transmission chains and calculates the required timing advance before the UE transmits PUSCH. This preliminary timing adjustment ensures that subsequent PUSCH transmissions arrive at the base station with accurate timing, eliminating the need for complex timing synchronization during data transmission while maintaining a structured multi-step random access procedure.
Data Source
AI summary
Embodiments of the present disclosure provide methods and apparatuses for random access procedure. A method performed by a terminal device comprises transmitting multiple preambles on different transmission chains of the terminal device to a network node. The multiple preambles are associated with a same or different synchronization signal and physical broadcast channel block (SSB).