RACH Msg3 Duration via Base Station Signaling

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Solution Overview

Problem

In wireless communication systems, the duration of a random-access channel (RACH) message 3 (Msg3) is often determined by the UE with the weakest link gain, leading to high overhead, while maintaining latency for most UEs.

Innovation Solution

The solution involves determining the number of RACH attempts based on path loss and configured transmit power, allowing UEs with weak link gain to transmit in multiple attempts, and combining signals across these attempts for decoding, thereby reducing RACH duration and overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the RACH duration is determined by the UE with the weakest link gain, then all UEs can be accommodated, but the RACH overhead becomes high

Engineering Contradiction:

Improvecoverage for weak link gain UEsVSAvoidRACH overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent segments the RACH procedure into multiple attempts (first attempt, second attempt, etc.) with different duration configurations. UEs with weak link gain can utilize extended duration in subsequent attempts, while UEs with good link gain complete access in the first attempt, thereby reducing overall overhead while maintaining coverage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic RACH duration configuration where the duration is not fixed but adapts based on UE conditions. The base station can configure different duration values for different RACH attempts, allowing the system to dynamically adjust resource allocation based on actual channel conditions and UE requirements.

Inventive Principle:

Principle #15Dynamics

2Reliability

If multiple RACH attempts are allowed for UEs with weak link gain, then coverage is improved, but latency increases

Engineering Contradiction:

Improvelink gain coverageVSAvoidRACH access latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary configuration of RACH parameters including duration for multiple attempts before the actual RACH procedure. This allows UEs to know in advance the expected duration for each attempt, enabling better resource planning and reducing uncertainty-induced delays.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enables UEs with good link gain to skip unnecessary waiting time by completing the RACH procedure in the first attempt with sufficient duration, while UEs needing more time can proceed to subsequent attempts. This allows strong UEs to rush through the process quickly without being held back by the requirements of weak UEs.

Inventive Principle:

Principle #21Skipping (Rushing through)

Data Source

PatentEP3566531B1Indication of random-access channel msg3 resource duration via random-access channel msg2

Publication Date: 2024.05.01 QUALCOMM INC

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AI summary

In one aspect, a method, a computer-readable medium, and an apparatus for wireless communication are provided. The apparatus may be a base station. The apparatus may determine a duration of an uplink message that is to be sent from a UE. The apparatus may inform the UE regarding the duration of the uplink message through a random-access response message.