The impact of message transmission scheduling in DTN message delivery across multiple islands

DTN have been employed widely to support various applications but among them, vehicle-based DTN on transportation infrastructure to deliver data is promising. In addition to routing protocols, message transmission scheduling is also very influential on DTN performance. Since nodes have a mobility and usually moving, a limited radio range and a limited duration of contact time can involve bottlenecks on message transmission in DTN. In this paper, we investigate the impact of message transmission scheduling on DTN message delivery across multiple islands that reflect a real example situation in Indonesia. We use our previous proposed A-SnHD as routing protocol, and evaluate the impact of message transmission scheduling by combining it with different scheduling schemes. One is a version of our previous proposed message scheduling called TTL-Loc modified to fit in the multiple island case. Other two are popular schemes, i.e., FIFO and Random. Two scenarios are examined. In 1s-to-2d scenario, a single source node sends different messages to two destination nodes located in different islands; not by multicast but by two different unicast deliveries. In the 2s-to-1d scenario, two source nodes located in different islands send different messages to a common destination node by two different deliveries. In both scenarios, our proposed TTL-loc scheduling is shown to have a better performance compared with FIFO and Random in terms of the amount of delivered messages before TTL-expiration. However the benefit of TTL-loc and its sensitivity differ depending on traffic load as well as the deliver scenarios.