Sidelink Logical Channel Prioritization for Resource Starvation
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Solution Overview
Problem
Current LTE V2X designs face issues of resource starvation among destination UEs, inadequate support for diverse communication ranges, and Hybrid Automatic Repeat Request (HARQ) collisions in sidelink transmission, particularly in NR V2X systems.
Innovation Solution
A method is proposed to prioritize sidelink logical channels during destination UE selection by maintaining a value Bj for each channel, ensuring that UEs with unsatisfied minimum bit rates are prioritized, and implementing a two-round resource allocation process to avoid resource starvation and manage HARQ processes effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transmitter UE always selects the destination UE with the highest-priority sidelink logical channel for transmission, then the highest-priority SL LCH can occupy the whole MAC PDU, but other destination UEs without the highest-priority SL LCH cannot be scheduled (resource starvation)
Solution Approach 1:
The patent segments the resource allocation process into two distinct rounds: first round allocates resources to satisfy prioritized bit rate requirements for all destination UEs, while the second round allocates remaining resources based on LCH priority. This segmentation resolves the contradiction by ensuring both QoS guarantees and efficient resource utilization among multiple destination UEs.
Solution Approach 2:
The patent performs preliminary action by first satisfying the prioritized bit rate requirements of all destination UEs before allocating resources based on LCH priority. This preliminary allocation ensures that all destination UEs receive minimum guaranteed resources, preventing resource starvation while still allowing highest-priority channels to occupy remaining resources.
2Quantity of substance
If a UE is configured with a huge SL grant to support large data transmission, then the transmission capacity is increased, but the UE may not be able to send the large SL grant with wide coverage due to power limitation
Solution Approach 1:
The patent introduces dynamic adjustment mechanisms where the UE can adaptively select transmission parameters including communication range based on available power and data volume. The system dynamically determines the appropriate communication range rather than being fixed, allowing optimization between transmission capacity and coverage area under power constraints.
Solution Approach 2:
The patent changes key transmission parameters including communication range, transmission power, and resource allocation based on real-time conditions such as available power and data volume. This parameter adjustment allows the system to optimize the trade-off between transmission capacity and communication range for different V2X application requirements.
3Adaptability or versatility
If both NW and UE can select SL resource for transmission in mixed mode operation, then resource flexibility is improved, but HARQ collision may occur when NW and UE perform SL transmission for the same destination UE and HARQ process ID
Solution Approach 1:
The patent implements feedback mechanisms where the network monitors and coordinates HARQ process IDs used by UEs in mixed mode operation. This feedback ensures that both network-scheduled and UE-autonomous transmissions use distinct HARQ processes, preventing collisions while maintaining the flexibility of mixed mode operation.
Solution Approach 2:
The network acts as an intermediary that coordinates HARQ process allocation between UE-autonomous and network-scheduled transmissions. By mediating the HARQ process ID assignment, the network prevents collisions while allowing both transmission modes to operate simultaneously with improved adaptability.
Data Source
AI summary
A method to prioritize sidelink logical channel (SL LCH) during destination UE selection for sidelink Logical Channel Prioritization (LCP) procedure in NR sidelink communication is proposed to avoid resource starvation. A TX UE prioritizes an RX UE having at least one SL LCH that has not satisfied a required minimum bit rate during destination UE selection when allocating SL resource to a new MAC PDU for SL transmission. The TX UE maintains a value Bj for each SL LCH j, where Bj>0 indicates that the logical channel has not met the requirement of prioritized bit rate. If at least one destination UE has SL LCH with data available for transmission and with Bj>0, then the selected destination UE is the one has the highest-priority SL LCH with data available for transmission and with Bj>0.