RACH BWP Switching with a Pre-Monitoring Time Gap

Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently managing bandwidth part (BWP) switching during the random access channel (RACH) procedure, leading to delays and increased power consumption at the user equipment (UE).

Innovation Solution

Implementing a time gap after transmitting a random access message and before starting a timer to monitor for a response, with the time gap being determined based on factors such as subcarrier spacing, bandwidth, and frequency gap between BWPs, allowing for efficient BWP switching and reduced power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the UE switches BWP after transmitting the random access message, then the power efficiency is improved by turning off the receiver, but the response message may be missed if the timer starts before the BWP switching is complete

Engineering Contradiction:

Improvepower efficiencyVSAvoidresponse message reception

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The UE performs BWP switching in advance before starting the timer for monitoring the response message. This preliminary action ensures that the receiver is already in the correct BWP state when the response message arrives, preventing message loss while allowing the UE to turn off the receiver during the idle period to save power.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE autonomously determines the time gap duration based on its own BWP switching capability and configuration, without requiring network coordination. This self-service approach allows the UE to optimize its power consumption by precisely controlling when to turn off and on the receiver based on its internal timing and switching requirements.

Inventive Principle:

Principle #25Self-service

2Loss of time

If the UE waits for the response message immediately after transmitting the random access message, then the response is received faster, but the UE cannot switch BWP and turn off the receiver to save power

Engineering Contradiction:

Improveresponse reception timeVSAvoidpower consumption

Core Design Contradiction:

Loss of timeVSUse of energy by moving object

Solution Approach 1:

The UE performs BWP switching in advance before starting the timer for monitoring the response message. This preliminary action ensures that the receiver is already in the correct BWP state when the response message arrives, preventing message loss while allowing the UE to turn off the receiver during the idle period to save power.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE dynamically adjusts the timing of the response message monitoring based on its BWP switching duration. By making the waiting period adaptive rather than fixed, the system optimizes the balance between quick response reception and power-saving opportunities, allowing the receiver to be turned off during the calculated time gap.

Inventive Principle:

Principle #15Dynamics

3Speed

If the time gap is determined without considering the BWP switching delay, then the timer starts earlier and response is received faster, but the UE may not be ready to receive in the correct BWP

Engineering Contradiction:

Improveresponse reception speedVSAvoidBWP switching timing accuracy

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The UE performs BWP switching in advance before starting the timer for monitoring the response message. This preliminary action ensures that the receiver is already in the correct BWP state when the response message arrives, preventing message loss while allowing the UE to turn off the receiver during the idle period to save power.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The time gap parameter is dynamically adjusted based on the actual BWP switching delay characteristics. By changing the time gap parameter to match the switching requirements, the system ensures that the timer starts at the correct moment when the UE is ready to receive in the new BWP, maintaining both speed and timing accuracy.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12464572B2BWP switching in RACH procedure

Publication Date: 2025.11.04 QUALCOMM INC

AI summary

A user equipment (UE) may transmit a first random access message to a base station in a first bandwidth part (BWP), switch from the first BWP to a second BWP, and start a timer following a time gap after transmission of the first random access message in the first BWP, the timer associated with a window of time for receiving a second random access message from the base station in the second BWP. The window of time may be a random access response (RAR) window or a contention resolution window that may extend until the expiration of the timer. The switch from the first BWP to the second BWP may be based on a subcarrier spacing (SCS) change from a first SCS to a second SCS.