Sidelink Unlicensed Resource Selection for LBT Failure Recovery

Solution Overview

Problem

Conventional resource selection methods for initial transmissions in sidelink unlicensed (SL-U) operations fail to handle listen-before-talk (LBT) failures effectively, leading to delays and unavailable resources for retransmissions.

Innovation Solution

Selecting a greater number of resources than the number of transport blocks for the initial transmission, allowing multiple listen-before-talk opportunities and minimizing transmission delay due to LBT failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a transmitter UE selects only the number of resources equal to the number of transport blocks for initial transmission, then resource allocation efficiency is improved, but transmission reliability deteriorates due to LBT failures in SL-U operations

Engineering Contradiction:

Improveresource allocation efficiencyVSAvoidtransmission reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The transmitter UE performs preliminary action by selecting and reserving multiple resources (N1) in advance for initial transmission, where N1 is greater than the number of transport blocks (N2). This preliminary resource allocation ensures that when LBT failures occur, there are already reserved resources available for retransmission without requiring additional resource selection procedures, thus maintaining both resource allocation efficiency and transmission reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention applies beforehand cushioning by allocating extra resources (N1 - N2) as a buffer against LBT failures. These additional reserved resources act as a cushion that absorbs the impact of LBT failures, ensuring that retransmissions can proceed using pre-allocated resources rather than requiring new resource selection, thereby preventing transmission delays and maintaining reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If multiple resources are selected for initial transmission to provide LBT opportunities, then transmission reliability is improved, but resource allocation efficiency deteriorates

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidresource allocation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The transmitter UE performs preliminary action by selecting and reserving multiple resources (N1) in advance for initial transmission, where N1 is greater than the number of transport blocks (N2). This preliminary resource allocation ensures that when LBT failures occur, there are already reserved resources available for retransmission without requiring additional resource selection procedures, thus maintaining both resource allocation efficiency and transmission reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the parameter of resource quantity from being equal to the number of transport blocks to being greater than the number of transport blocks. By setting N1 > N2, the system transforms the resource allocation parameter to provide built-in redundancy for LBT failures, improving transmission reliability while the resources are efficiently utilized through pre-allocation rather than waste.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional resource selection is used in SL-U operations, then device complexity is reduced, but transmission delay increases due to LBT failure handling

Engineering Contradiction:

Improveresource selection complexityVSAvoidtransmission delay

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The transmitter UE performs preliminary action by selecting and reserving multiple resources (N1) in advance for initial transmission, where N1 is greater than the number of transport blocks (N2). This preliminary resource allocation ensures that when LBT failures occur, there are already reserved resources available for retransmission without requiring additional resource selection procedures, thus maintaining both resource allocation efficiency and transmission reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention extracts the resource selection function from the retransmission process. By pre-selecting and reserving multiple resources (N1) in advance, the system removes the need for complex resource selection operations during retransmission after LBT failures. The resource selection is performed once initially, and the same reserved resources are used for retransmissions, thereby reducing device complexity and avoiding additional transmission delays.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20250247826A1Sidelink unlicensed (SL-u) resource selection for listen-before-talk (LBT) procedure

Publication Date: 2025.07.31 QUALCOMM INC

AI summary

Certain aspects of the present disclosure provide a method for wireless communications by a transmitter user equipment (UE). The method may include selecting a first number of resources for an initial transmission based on a second number of transport blocks (TBs) for the initial transmission where the first number is greater than the second number, and transmitting the initial transmission on one or more of the first number of resources.