Semi-persistent scheduling for V2X latency
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Solution Overview
Problem
Current semi-persistent scheduling mechanisms in LTE systems struggle to meet the low latency and high capacity requirements of Vehicle-to-X (V2X) communication, especially in high vehicle density scenarios like urban areas, due to unpredictable packet size and generation frequency, and variable message periodicity.
Innovation Solution
The proposed solution involves configuring multiple inter-dependent semi-persistent scheduling occasions, where the user equipment can indicate the usage of subsequent scheduling occasions during main scheduling occasions, allowing for dynamic adjustment of physical resource blocks and modulation and coding schemes to align with V2X message generation time and size, enhancing resource utilization and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If legacy LTE semi-persistent scheduling is used for V2X communication, then signaling overhead is reduced, but latency requirements cannot be met in high vehicle density scenarios
Solution Approach 1:
The patent introduces dynamic adjustment mechanisms for semi-persistent scheduling parameters based on V2X traffic conditions. The network can dynamically modify scheduling occasion periodicity, resource allocation, and activation/deactivation timing to adapt to varying traffic loads and latency requirements, transforming the static legacy SPS into a dynamic system that balances signaling overhead and latency performance
Solution Approach 2:
The patent enables changing key SPS parameters such as scheduling occasion periodicity, resource block allocation, and modulation and coding schemes based on V2X traffic characteristics. By allowing parameter adjustments without full reconfiguration signaling, the system reduces latency while maintaining lower signaling overhead compared to dynamic scheduling
2Device complexity
If semi-persistent scheduling with fixed periodicity is used, then resource allocation is simplified, but it cannot adapt to variable V2X packet generation frequency and message size
Solution Approach 1:
The patent makes semi-persistent scheduling dynamic by allowing the network to adjust scheduling occasion periodicity and resource allocation based on observed V2X traffic patterns. This enables the system to adapt to variable packet generation frequency and message size while maintaining the simplified resource allocation framework of SPS
Solution Approach 2:
The patent uses preliminary configuration of multiple scheduling occasions with different periodicities, allowing the network to pre-prepare resource allocations that can be activated or deactivated based on actual traffic conditions. This preliminary action enables rapid adaptation without complex real-time negotiation
3Adaptability or versatility
If multiple V2X services with different periodicities are supported, then service versatility is improved, but prediction of message size and interval becomes more challenging
Solution Approach 1:
The patent segments the scheduling of different V2X services by configuring separate semi-persistent scheduling occasions with service-specific periodicities and resource allocations. This segmentation allows each service to be managed independently, making prediction easier while maintaining support for multiple services with different characteristics
Data Source
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AI summary
Various communication systems benefit from suitable allocation. For example, system for vehicle to X communication may benefit from semi-persistent resource allocation mechanisms, for example, for uplink semi-persistent scheduling. A method can include configuring at least one main semi-persistent scheduling occasion to a user equipment. The method can also include configuring at least one subsequent semi-persistent scheduling occasion to the user equipment. The at least one subsequent semi-persistent scheduling occasion can depend on usage of the at least one main semi-persistent scheduling occasion.