Two-Step Random Access Timing in Unlicensed Bands
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently performing a two-step random access procedure in an unlicensed band, particularly in terms of signal transmission and reception.
Innovation Solution
A method and apparatus for transmitting and receiving signals for performing a random access channel (RACH) procedure in an unlicensed band, involving the reception of a synchronization signal/physical broadcast channel (SS/PBCH) block, obtaining system information, transmitting a first physical random access channel (PRACH) preamble, and receiving a random access response (RAR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-step random access procedure is implemented in an unlicensed band, then communication capacity and reliability are improved, but signal transmission and reception efficiency deteriorates due to existing system limitations
Solution Approach 1:
The patent implements dynamic timing adjustments for Message B reception window based on Message A transmission timing. The reception window is configured to start at a first symbol of a resource related to monitoring of Message B, with flexible timing relationships that adapt to different transmission scenarios, thereby optimizing both reliability and efficiency in unlicensed band operations
Solution Approach 2:
The patent modifies key timing parameters including setting the Message B reception window to start at least one symbol after a last symbol of PUSCH occasion, and configuring the relationship between PRACH preamble transmission and PUSCH occasion timing. These parameter optimizations resolve the contradiction by achieving reliable signal detection while maintaining transmission efficiency
2Productivity
If PRACH preamble is mapped to PUSCH occasion for Message A, then resource utilization is improved, but timing synchronization complexity increases
Solution Approach 1:
The patent segments the random access procedure into distinct phases with clear timing relationships: PRACH preamble transmission in Message A, followed by Message B reception in a configured window. By separating the timing configuration into manageable components (PUSCH occasion timing, Message B window timing), the patent reduces synchronization complexity while maintaining high resource utilization
Solution Approach 2:
The patent configures timing parameters in advance through system information or RRC signaling, including the Message B reception window timing relative to PUSCH occasion. This preliminary configuration eliminates the need for dynamic timing calculations during execution, reducing operational complexity while preserving resource efficiency
Data Source
AI summary
Disclosed is a method for transmitting and receiving a signal for a terminal to perform a random access channel procedure (RACH Procedure) in an unlicensed band. In particular, the method comprises: receiving a synchronization signal/physical broadcast channel block (SS/PBCH block); obtaining system information from a PBCH included in the SS/PBCH block; sending a first physical random access channel (PRACH) preamble through a message A on the basis of the system information; and receiving a random access response (RAR) through a message B related to contention resolution in response to the message A, wherein the first PRACH preamble is a PRACH preamble mapped to a physical uplink shared channel (PUSCH) occasion for the message A, and a window for reception of the message B may start after at least one symbol from the last symbol of the PUSCH occasion.