Sidelink Back-Scheduling for Low-Latency LBT Slot Access
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Solution Overview
Problem
Existing sidelink communication technologies face inefficiencies and latency issues in unlicensed spectrum due to the uncertainty of Listen Before Talk (LBT) procedures, leading to delayed or lost transmission opportunities.
Innovation Solution
A transmitter device is configured to perform a Listen-Before-Talk procedure during a current time slot and transmit PSSCH at a starting point within the same slot if successful, with associated PSCCH transmission occurring either in the same or next slot, utilizing backup or auxiliary resources to indicate PSSCH resources, and a receiver device is equipped to decode these transmissions using stored slots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT procedure is performed during a current time slot with PSCCH occasion, then channel access is achieved, but transmission latency increases due to waiting for next slot boundary
Solution Approach 1:
The patent performs preliminary LBT procedure during the current time slot at the PSCCH occasion to secure channel access in advance. By completing the LBT check before the slot boundary, the system prepares the channel access status preliminarily, enabling immediate PSSCH transmission without waiting for the next slot start, thus resolving the contradiction between reliable channel access and transmission latency
Solution Approach 2:
The patent dynamically adjusts the transmission timing based on LBT outcome. When LBT succeeds during the current slot, the system transitions from the traditional fixed slot-boundary transmission to flexible immediate transmission. This dynamic timing adjustment allows the system to exploit available channel access opportunities without being constrained by rigid slot structures, reducing latency while maintaining reliable channel access
2Device complexity
If PSSCH transmission is delayed to next slot boundary, then transmission timing is simplified, but transmission opportunities are lost due to channel occupancy by other devices
Solution Approach 1:
The system performs preliminary channel assessment and LBT procedure during the current slot to determine transmission feasibility in advance. This preliminary action enables the system to capture immediate transmission opportunities when the channel is available, rather than waiting for the next slot boundary when other devices may have occupied the channel, thus improving transmission opportunity utilization without significantly increasing timing management complexity
Solution Approach 2:
The patent introduces dynamic transmission timing that adapts to real-time channel conditions. When LBT succeeds during the current slot, transmission is scheduled immediately; when it fails, transmission is deferred to the next slot boundary. This dynamic approach allows the system to flexibly seize transmission opportunities while maintaining manageable timing complexity through clear decision rules
3Loss of information
If PSCCH is transmitted before PSSCH, then resource indication is clear, but transmission flexibility is reduced when LBT succeeds after PSCCH occasion
Solution Approach 1:
The patent transmits PSCCH preliminarily during the current slot to indicate upcoming PSSCH resources. When LBT succeeds after PSCCH occasion, the system uses this preliminary resource indication to schedule immediate PSSCH transmission. This preliminary action maintains resource indication clarity while enabling flexible immediate transmission, resolving the contradiction between clear resource indication and transmission scheduling flexibility
Solution Approach 2:
The system dynamically adjusts the relationship between PSCCH and PSSCH timing based on LBT outcomes. Traditionally, PSCCH is transmitted before PSSCH with fixed timing. The patent introduces dynamic flexibility where, when LBT succeeds during the current slot, PSSCH can be transmitted immediately after PSCCH without waiting for slot boundary. This dynamic adjustment maintains clear resource indication through PSCCH while significantly improving transmission scheduling flexibility
Data Source
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AI summary
There is provided a method of sending a sidelink transmission from a wireless transmitter device to a receiver device, connected through a wireless communication network, through one or more time slots, the sidelink transmission comprising performing a Listen-Before-Talk (LBT) procedure during a current time slot, a time slot comprising a PSCCH occasion with a number of PSCCH candidates corresponding to time-frequency resources, wherein the sidelink transmission comprises: - sending (904) a PSSCH transmission to the receiver device at a starting point within said current time slot and before the next time slot is reached, if the LBT procedure is successful after the starting of a PSCCH occasion; and then - sending (906) a PSCCH transmission to the receiver device, after the start of the PSSCH transmission, said PSCCH transmission back indicating the PSSCH, the PSCCH carrying Sidelink Control Information SCI..