On the utility of overhearing in DTN

Limited contact bandwidth is one of the main resource constraints in delay/disruption tolerant network (DTN). In this paper, we investigate the use of overhearing to relieve the bandwidth constraint. We ask two questions in this work. First, how many receivers are within the transmission range when a sender transmits? Second, how does the larger bandwidth achieved through overhearing improve routing performance? For the first question, we analyze available mobility traces and empirically quantify the amount of potential transmission gains through overhearing. We find that the increase can be significant. For one of the traces, the gain is 10 times that of unicast. For the second question, we experiment with different approaches to enhance existing DTN routing to exploit overhearing. We find that the improvement in delivery ratio can be up to 50%.