A QoS-Aware Utility-Based Forwarding Strategy for Opportunistic Routing in Vehicular Ad Hoc Networks (VANETs)

Opportunistic routing improves robustness in Vehicular Ad Hoc Networks (VANETs) by delaying relay selection until transmission time, but baseline schemes may not explicitly optimize Quality-of-Service (QoS) requirements such as delay, jitter, and bandwidth. This paper proposes A-BOR (Adaptive BOR), a QoS-aware enhancement of Bitmap-Based Opportunistic Routing (BOR) that ranks candidate forwarding options using a lightweight utility function and a feedback mechanism to refresh QoS indicators under dynamic conditions. A routing-layer VANET simulation with 100 mobile nodes under Manhattan-grid mobility is used for evaluation with Time-to-Live (TTL) = 60 s, 500 injected packets over a 200 s injection window, and a 600 s simulation duration. Results over 50 independent runs (mean ± 95% confidence interval) show that A-BOR improves packet delivery ratio (0.254 ± 0.023 vs 0.089 ± 0.009) and throughput (2598.5 ± 231.8 bps vs 906.4 ± 95.9 bps) compared with BOR, while reducing mean end-to-end delay (39.37 ± 1.25 s vs 41.96 ± 1.68 s) and jitter (5.04 ± 0.62 s vs 12.81 ± 1.90 s). These findings indicate that QoS-aware utility-based relay selection with feedback can improve reliability and delivery stability in dynamic VANET environments.