Unlicensed Sidelink Guard-Duration Timing for Reliable COT Sharing
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Solution Overview
Problem
In sidelink communication using unlicensed spectrum, the guard symbol duration is insufficient to prevent other devices from occupying the channel during channel occupancy time (COT) sharing, compromising the integrity of COT sharing between initiating and responding UEs.
Innovation Solution
Adjust the time gap between transmissions by initiating and responding UEs such that the guard duration is optimized to allow the responding UE to perform a channel access procedure while preventing other devices from taking over the channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guard symbol duration is extended to allow responding UE to perform channel access procedure, then the channel access reliability is improved, but the channel occupancy time efficiency deteriorates due to increased idle time
Solution Approach 1:
The patent adjusts the guard symbol duration parameter to an optimized value that balances two competing requirements: it is long enough to allow the responding UE to perform a shortened channel access procedure (improving reliability) but short enough to minimize idle time and maintain channel occupancy efficiency. This parameter optimization resolves the contradiction by finding the optimal point in the trade-off curve.
2Loss of time
If the guard duration is shortened to improve channel occupancy efficiency, then the time loss is reduced, but the responding UE cannot complete channel access procedure reliably
Solution Approach 1:
The patent applies a shortened channel access procedure (partial action) instead of the full procedure, which reduces the time required for channel access while still providing sufficient reliability. This partial action approach allows the system to achieve adequate channel access reliability with a shorter guard duration, thereby improving channel occupancy efficiency without completely sacrificing access reliability.
3Productivity
If other devices are allowed to occupy the channel during guard duration, then the channel utilization is improved, but the COT sharing integrity between initiating and responding UEs deteriorates
Solution Approach 1:
The patent applies preliminary anti-action by having the initiating UE transmit energy during the guard symbol period in advance, which prevents other devices from successfully performing clear channel assessment and occupying the channel. This preliminary transmission acts as a deterrent that maintains COT sharing integrity by ensuring the channel remains reserved for the intended responding UE, while still allowing efficient use of the guard period.
Data Source
AI summary
A user device, UE, for a wireless communication network, like a 3rd Generation Partnership Project, 3GPP, network, is described. The UE is to perform a sidelink, SL, communication using a channel including resources from an unlicensed spectrum. The UE is to occupy the channel within a channel occupancy time, COT, and share the COT with a further UE, wherein the COT has a first part and a second part, the first part of the COT and the second part of the COT being separated by a guard duration. The UE is to perform a transmission over the SL during the first part of the COT. The second part of the COT is used by the further UE to perform a transmission over the SL. The UE is to extend the transmission into the guard duration so as to transmit during a predefined time duration starting at the beginning of the guard duration, the predefined time duration selected such that a remaining duration of the guard duration is sufficient to allow the further UE to perform a predefined channel access procedure, CAP, before accessing the shared COT.