Two-Step RACH Signaling with Transform-Precoded PUSCH
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Solution Overview
Problem
The existing wireless communication systems face challenges in efficiently performing the random access channel (RACH) procedure, particularly in next-generation wireless communication systems that require improved communication capacity, massive machine-type communications, and ultra-reliable and low-latency communications.
Innovation Solution
A method for transmitting and receiving signals for performing a 2-step RACH procedure by a user equipment (UE) in a wireless communication system, involving the reception of first information about a transform precoder related to a physical random access channel (PRACH) and a physical uplink shared channel (PUSCH), and the transmission of a message A including both PRACH and PUSCH based on this information, with the UE receiving a message B containing contention resolution information as a response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 4-step RACH procedure is used, then compatibility with existing systems is maintained, but access latency and procedure complexity increase
Solution Approach 1:
The patent merges the traditional 4-step RACH procedure into a 2-step procedure by combining Message 1 and Message 3 into a single Message A, and combining Message 2 and Message 4 into a single Message B. This reduces the number of round-trip transmissions and minimizes access latency while maintaining access reliability through integrated uplink data transmission in Message A.
Solution Approach 2:
The patent segments the RACH procedure into two distinct messages: Message A containing PRACH preamble and PUSCH data, and Message B containing random access response and contention resolution. This segmentation allows for more efficient resource allocation and reduces the overall procedure time compared to the traditional four-message exchange.
2Productivity
If transform precoding is applied to PUSCH in Message A, then uplink transmission efficiency is improved, but system complexity and configuration overhead increase
Solution Approach 1:
The patent applies transform precoding to the PUSCH in Message A by changing the modulation scheme from conventional QAM to DFT-s-OFDM. This parameter change improves uplink transmission efficiency, particularly for mobile scenarios, while the network configures the transform precoding mode through higher-layer signaling to manage system complexity.
Solution Approach 2:
The patent introduces dynamic transform precoding configuration where the network can adaptively enable or disable transform precoding based on channel conditions and UE capabilities. This dynamic approach optimizes uplink transmission efficiency while managing system complexity through flexible configuration rather than fixed implementation.
3Loss of time
If Message A includes both PRACH and PUSCH, then random access speed is improved, but signal processing complexity and error probability increase
Solution Approach 1:
The patent merges PRACH preamble transmission and PUSCH data transmission into a single Message A, reducing random access time by eliminating the need for separate transmission steps. The merged message is processed as a unified structure with transform precoding applied to the PUSCH portion, balancing speed improvement with manageable signal processing complexity.
Data Source
AI summary
The present disclosure provides a method whereby a terminal transmits and receives signals for carrying out a random access channel (RACH) procedure in a wireless communication system. In particular, the method comprises: receiving first information about a transform precoder related to a physical uplink shared channel (PUSCH) transmitted via message A; on the basis of the first information, transmitting message A including the PUSCH and a physical random access channel (PRACH); and in response to message A, receiving message B including contention resolution information, wherein the first information may be used to indicate transform precoding for the PUSCH on the basis that the PUSCH is transmitted via message A.