Random Access Response Detection for 2-Step RACH Latency
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Solution Overview
Problem
The existing 2-step RACH procedure lacks a clear method for obtaining a response to the MsgA, which is crucial for efficient data transmission in ultra-reliable low-latency communications, especially in scenarios requiring sparse packets and low latency.
Innovation Solution
A method is provided where user equipment sends a random access message comprising a preamble and uplink data, followed by detecting downlink control information within a defined time window to receive responses for both the preamble and uplink data, utilizing multiple control channel resource sets and search spaces to adaptively adjust the transmission mode based on detection status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the 2-step RACH procedure combines steps to accelerate random access, then the random access latency is reduced, but the method for obtaining response to MsgA is not resolved
Solution Approach 1:
The patent segments the response detection process into two separate time windows: a first time window for detecting RAR (Random Access Response) and a second time window for detecting contention resolution information. This segmentation allows the UE to systematically handle different response types in the 2-step RACH procedure, resolving the complexity of obtaining response to MsgA while maintaining the accelerated random access latency.
2Adaptability or versatility
If multiple control channel resource sets are used for response detection, then the adaptability of transmission mode is improved, but the complexity and power consumption of user equipment increases
Solution Approach 1:
The patent implements dynamic adaptability by allowing the UE to flexibly select between a first control channel resource set and a second control channel resource set based on detection status. The UE can adaptively adjust which resource set to monitor, enabling flexible transmission modes while managing power consumption through conditional monitoring rather than continuous monitoring of all resource sets.
3Loss of time
If the first time window starts at the first symbol of a control channel resource set after preamble transmission, then the response detection timing is optimized, but the flexibility in handling different transmission scenarios is reduced
Solution Approach 1:
The patent applies preliminary action by defining the first time window to start at a predetermined position (first symbol of a control channel resource set after preamble transmission). This preliminary timing setup optimizes response detection while the patent simultaneously maintains flexibility through configurable window lengths and the option to adjust timing based on different transmission scenarios, balancing timing optimization with scenario adaptability.
Data Source
AI summary
This application provides a method and a communication apparatus. The method includes: receiving a random access message of a first-type random access procedure, wherein the random access message of the first-type random access procedure comprises a random access preamble and uplink data; and sending first downlink control information (DCI) or second DCI within a first window, wherein the first DCI is for scheduling a first physical downlink shared channel (PDSCH) that carries a first response message for the random access preamble, and the second DCI is for scheduling a second PDSCH that carries a second response message for the random access message.