Sidelink Resource Selection via LBT and Multi-SCI Decoding
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Solution Overview
Problem
Current cellular systems face challenges in increasing throughput due to bandwidth limitations in licensed spectra, and existing sidelink communication methods over unlicensed bands suffer from significant transmission delays, hidden node problems, uncoordinated serving, and inapplicability of HARQ retransmission on control channels.
Innovation Solution
Implementing a method that involves conducting a listen-before-talk (LBT) process on unlicensed bands to select sidelink resources, decoding multiple Sidelink Control Information (SCI) messages to prioritize resource selection, and adjusting selection windows and RSRP thresholds based on receiving UE's decoding capabilities to reduce interference and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional sidelink resource selection is used on unlicensed bands, then device simplicity is maintained, but transmission delays increase significantly
Solution Approach 1:
The patent applies preliminary action by performing LBT channel access procedures and decoding multiple SCI messages before final resource selection. The transmitting UE conducts channel sensing, decodes up to 3 SCI messages from other UEs, and identifies preferred resources in advance, which reduces transmission delays by avoiding last-minute resource conflicts while managing complexity through structured pre-processing steps.
Solution Approach 2:
The patent implements feedback mechanisms where UEs report their SCI decoding capabilities and channel sensing results to each other. This feedback enables dynamic adjustment of resource selection strategies, allowing the system to optimize transmission timing based on real-time channel conditions and receiver capabilities, thereby reducing delays without requiring overly complex predetermined protocols.
2Object-affected harmful factors
If single SCI decoding is used per PSCCH resource, then device complexity is reduced, but hidden node interference cannot be mitigated
Solution Approach 1:
The patent applies preliminary action by decoding multiple SCI messages (up to 3) from different transmitting UEs before selecting transmission resources. This allows the receiving UE to identify potential hidden node interferers in advance and adjust its resource selection accordingly, mitigating interference while managing complexity through a structured decoding process that stops after a maximum number of successful decodings.
Solution Approach 2:
The patent implements partial action by decoding a limited number of SCI messages (maximum 3 per PSCCH resource) rather than attempting to decode all possible signals. This partial decoding approach provides sufficient information to mitigate hidden node interference in practical scenarios while keeping device complexity manageable by not requiring exhaustive decoding of all channel signals.
3Productivity
If fixed resource selection window size is used, then ease of operation is maintained, but network throughput cannot be optimized
Solution Approach 1:
The patent implements dynamic resource selection window sizing based on the receiving UE's reported SCI decoding capability. When the receiver can decode more SCI messages, the transmitter uses a larger resource selection window to identify more preferred resources, thereby optimizing throughput. This dynamic adjustment maintains ease of operation through automated capability reporting and processing while enabling throughput optimization adapted to each UE pair's capabilities.
Solution Approach 2:
The patent changes the parameter of resource selection window size dynamically based on decoded SCI message counts and receiver capabilities. By adjusting this parameter according to real-time channel conditions and UE capabilities, the system optimizes network throughput without requiring manual configuration, maintaining ease of operation through automated parameter adaptation.
4Reliability
If LBT process is conducted for each transmission, then channel access reliability is improved, but transmission latency increases
Solution Approach 1:
The patent applies preliminary action by conducting LBT channel access procedures in advance during the resource selection phase. The transmitting UE performs channel sensing and secures channel access before finalizing resource selection, which ensures reliable channel access while reducing latency by avoiding repeated LBT attempts during actual transmission. This preliminary LBT approach manages the reliability-latency tradeoff by front-loading the channel access procedure.
Data Source
AI summary
A method is provided, which includes conducting, at a first user equipment (UE), a listen-before-talk (LBT) process on an unlicensed band to obtain a channel occupancy time (COT) for a sidelink transmission; determining, at the first UE, based on channel sensing executed on the unlicensed band, a group of candidate sidelink resources on the unlicensed band, where each candidate side link resource is within a sidelink resource selection window, and does not have reservation that is associated with a Reference Signal Received Power (RSRP) higher than a predetermined resource exclusion RSRP threshold; selecting, at the first UE, a sidelink resource from the group of candidate sidelink resources; and performing, on the selected sidelink resource, the sidelink transmission from the first UE to a second UE, within the obtained COT. Multiple Sidelink Control Information (SCI) messages are decoded at the first UE on a single Physical Sidelink Control Channel (PSCCH) resource.