Timing Advance Indication in Two-Step RACH via Reserved Bit Replacement

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Solution Overview

Problem

Current wireless communication systems face delays in the two-step random access channel (RACH) procedure due to inefficiencies in timing advance (TA) indication, which can lead to delayed communications and increased network load from repeated attempts.

Innovation Solution

The solution involves the base station replacing reserved bits in the downlink control message with TA indication, allowing for accurate timing advance transmission, even if the UE cannot decode the second RACH message, and adjusting the TA granularity to fit within available bits, ensuring reliable communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the base station includes TA indication in the downlink control message using reserved bits, then the timing advance transmission becomes more reliable and latency is reduced, but the device complexity increases due to bit replacement and granularity adjustment

Engineering Contradiction:
ImproveRACH procedure latencyVSAvoidbase station processing complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent extracts the TA indication from the second RACH message payload and places it in the downlink control message using reserved bits. This extraction allows the UE to obtain TA information earlier, before attempting to decode the second RACH message, thereby reducing the overall RACH procedure latency while managing complexity through structured bit field manipulation

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter allocation in the downlink control message by replacing reserved bits with TA indication. Additionally, it adjusts the TA granularity to fit within the available bit fields, optimizing the balance between information completeness and message structure constraints

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the TA indication is included in the downlink control message, then communication can proceed without additional RACH attempts, but the available bits for other control information are reduced

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidcontrol information capacity
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The TA indication is extracted from the second RACH message and placed in the downlink control message, allowing critical timing information to be transmitted separately. This ensures that even if the UE cannot decode the second RACH message, it can still obtain the TA indication and proceed with communication, thereby maintaining productivity while managing information capacity through strategic bit allocation

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3909320B1Timing indication for a two-step random access channel procedure
Publication Date: 2023.11.15 QUALCOMM INC
  • EP3909320B1 patent drawingFigure 1
  • EP3909320B1 patent drawingFigure 2
  • EP3909320B1 patent drawingFigure 3

AI summary

Methods, systems, and devices for a two-step random access channel (RACH) procedure are described that may enable a user equipment (UE) and a base station to perform a two-step RACH procedure and begin communications using an accurate timing advance (TA). The UE may send a first RACH message of the two-step RACH procedure to the base station. The base station may determine an accurate TA based on the contents of the first RACH message. The base station may prepare a downlink control message and a corresponding second RACH message to send to the UE. The base station may include scheduling information for the second message and an indication of the TA in the downlink control message. The base station may identify one or more data fields in bits within the downlink control message reserved for information other than the TA and replace the bits with the TA indication.