Fairness-Oriented Semi-Distributed Power Coordination for NOMA-Enabled V2V Communications

Abstract

Underlay reuse of cellular-user (CU) subchannels by vehicle-to-vehicle (V2V) links improves spectrum utilization but may cause CU outage in non-orthogonal multiple access (NOMA)-enabled vehicular networks. This paper studies fairness-oriented V2V power coordination with CU outage protection under imperfect successive interference cancellation. Using the Cantelli inequality, the probabilistic CU outage constraint is converted into a deterministic, locally computable V2V transmit-power bound. Based on this bound, we develop a semi-distributed mixed-SPS scheme that performs topology-aware clustering and CU-subchannel reuse in the reservation phase and local V2V power adaptation in the data phase. The proposed interference-minimizing graph-based clustering algorithm reduces receiver-overlap-induced intra-cluster interference, and the proposed COVA method exploits the derived outage-aware bound to protect CUs without requiring global instantaneous CSI. Simulation results show that the proposed scheme reduces V2V service-packet transmission delay and improves delay-fairness and packet reception performance under dense V2V reuse, imperfect SIC, and different CU outage requirements.