Empirical performance evaluation of data dissemination mechanisms for spot applications

We evaluate, by measurements on a real testbed, the performance of networking services required for spot applications. We call a “spot application” an application for smartphones (such as “Ad-hoc Flash Sales”) that disseminates information in a local neighborhood through hop-by-hop wireless forwarding. The dissemination environment is challenging. It is open-ended, and highly dynamic with very limiting resource constraints. We define five success criteria that are required by a spot application to ensure a sustainable dissemination. They cover issues such as adaptability, resource conserving and co-existence with TCP applications. We evaluate a package of mechanisms and we identify how those, through their interaction, can altogether meet these criteria. This package includes flow control, forwarding factor control and buffer management. Our measurements are carried out on a realistic testbed composed of 50 wireless devices. Our metrics include spread, application rate, forwarding factor and delay. Some findings are: blind mechanisms can interact among each other to meet the success criteria; aging entails intolerable processing complexity for smartphones; and TTL-based buffer management performs poorly with large buffer size.