Sidelink Unlicensed Spectrum Access with Dynamic CPE Timing

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Solution Overview

Problem

The determination of cyclic prefix extension (CPE) length and channel access procedure type for sidelink (SL) transmissions on unlicensed spectrum is unclear, leading to inefficiencies in maintaining channel occupancy time (COT) and ensuring proper transmission gaps.

Innovation Solution

A method for determining the cyclic prefix extension period based on the number of channel access procedures performed for sidelink transmissions, using a processor to configure the transmission starting point before the first SL OFDM symbol, and adjusting the CPE period based on the type and number of channel access procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed cyclic prefix extension period is used for sidelink transmissions, then the transmission structure is simple, but the channel occupancy time cannot be maintained effectively and transmission success rate decreases

Engineering Contradiction:

Improvetransmission success rateVSAvoidCPE length determination complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the cyclic prefix extension period variable rather than fixed. The CPE length is dynamically adjusted based on the number of channel access procedures performed, allowing the system to adapt to different channel conditions and maintain COT effectively, thereby improving transmission success rate while managing complexity through a clear adjustment rule.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of cyclic prefix extension period from a fixed value to a variable that depends on the number of channel access procedures. This parameter change enables the system to optimize transmission performance under different conditions, resolving the contradiction between reliability and complexity by providing a systematic method for parameter adjustment.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If the transmission gap between consecutive sidelink transmissions is reduced to maintain COT, then channel occupancy is maintained, but the cyclic prefix extension period becomes insufficient without dynamic adjustment

Engineering Contradiction:

Improvechannel occupancy timeVSAvoidtransmission timing precision

Core Design Contradiction:

Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

The patent uses dynamics to adjust the cyclic prefix extension period based on the number of channel access procedures performed. This dynamic adjustment ensures that the transmission timing is precisely controlled even when transmission gaps are reduced to maintain COT, resolving the contradiction between duration and precision.

Inventive Principle:

Principle #15Dynamics

3Reliability

If multiple channel access procedures are performed for sidelink transmission, then channel access success rate improves, but the transmission delay increases

Engineering Contradiction:

Improvechannel access success rateVSAvoidtransmission delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing channel access procedures in advance and using the cyclic prefix extension period to compensate for the time required. The CPE is configured based on the number of channel access procedures, allowing the system to prepare for potential delays and maintain timing synchronization, thus reducing the impact of multiple access procedures on overall transmission delay.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250219882A1Method and apparatus for sidelink operation on unlicensed spectrum

Publication Date: 2025.07.03 ZTE CORP

AI summary

A wireless communication method for use in a wireless terminal is disclosed. The method comprises performing a channel access procedure on a channel based on a transmission starting point for a sidelink transmission, wherein the transmission starting point is a cyclic prefix extension period before/preceding the first SL OFDM symbol of a SL slot configured for the sidelink transmission, and wherein the cyclic prefix extension period is determined based on a number of channel access procedures performed for the sidelink transmission.