A Flexible Resource Allocation Scheme for NR V2X Based Vulnerable Road User Protection

New Radio (NR) Vehicle-to-Everything (V2X) based Vulnerable Road User Protection (VRUP) can effectively reduce traffic accidents, making it a promising application in intelligent transport systems. However, considering the scarcity of radio resources and the inefficiency of resource allocation, the performance reduction caused by resource collisions may restrict its development in the V2X network. In this paper, we propose a flexible resource allocation scheme, namely Zone cluster Resource Reuse (ZRR), to reduce resource collision and achieve a better delivery performance of NR V2X based VRUP. We then develop a theoretical framework based on stochastic geometry to efficiently characterize the VRUP message delivery process under ZRR, taking into account the specified factors of NR V2X. With the help of the framework, we are able to derive two important performance metrics, namely message delivery probability and the User Equipment (UE) transmit power, and we can further search for the optimal parameter setting of ZRR. Extensive simulation and theoretical results are provided to demonstrate the effectiveness of ZRR and the framework. Under the optimal parameter setting, ZRR is very desirable for VRUP message delivery, especially in the resource-constrained and access-intensive scenario.