Voice messaging for mobile delay-tolerant networks

Mobile ad-hoc networks, especially when they are sparse, are not well suited for ad-hoc voice communication when using end-to-end real-time audio streams: as paths grow in length, stability and forwarding performance suffer, and sometimes paths may not exist at all. In this paper, we suggest using asynchronous voice messaging built upon delay-tolerant networking concepts with some degree of hop-by-hop reliability to enable communication even in sparse environments and ensure intelligible speech. We evaluate the resulting walkie-talkie-style service in different synthetic and mobility-trace-driven settings and report on our experience from interoperable implementations on various mobile device platforms.