Two-Step RACH Fallback Based on Channel Quality
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Solution Overview
Problem
The inclusion of a payload in the initial message of the two-step random access channel (RACH) procedure in wireless communication systems reduces the link budget and cell coverage compared to the four-step RACH procedure, due to the larger message size.
Innovation Solution
A method is provided to determine whether to perform a two-step or four-step RACH procedure based on downlink measurements, such as reference signal received power (RSRP) and path loss, allowing the UE to dynamically adjust the random access procedure to optimize channel quality and coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a payload is included in the initial message of the two-step RACH procedure, then the random access procedure is simplified and completed faster, but the link budget and cell coverage are reduced
Solution Approach 1:
The patent implements dynamic selection between two-step and four-step RACH procedures based on real-time channel conditions. The UE determines whether to use the two-step procedure with payload inclusion or fallback to the four-step procedure based on measured channel quality metrics such as RSRP and path loss, allowing the system to adapt to varying link conditions optimally
Solution Approach 2:
The patent changes the message structure parameter dynamically - using a compact initial message format (msgA) with embedded payload for two-step procedure when channel conditions permit, versus the traditional separated message format (msg1, msg3) for four-step procedure when coverage requirements demand, thus optimizing both efficiency and reliability based on channel parameters
2Loss of time
If the initial message size is increased to include payload information, then the number of message exchanges is reduced, but the transmission reliability deteriorates
Solution Approach 1:
The system dynamically adjusts the message structure based on channel conditions - using the compact msgA format with payload when time efficiency is prioritized and channel quality supports it, and falling back to the more reliable but longer four-step procedure when transmission reliability becomes more critical, thus balancing time loss and reliability dynamically
Data Source
AI summary
Apparatus, methods, and computer-readable media for performing random access procedures based on two-step random access channel procedures and four-step random access channel procedures are disclosed herein. An example method for wireless communication at a User Equipment (UE) includes determining that a fallback timer associated with a two-step random access procedure is configured for the UE. The example method also includes generating a random access message based at least on the determining. The random access message may be one of a first-type random access message associated with a four-step random access procedure and including a preamble or a second-type random access message associated with the two-step random access procedure and including the preamble and a payload. Further, the example method includes performing a random access attempt by transmitting, to a base station, the random access message.