Hermes: Data transmission over unknown voice channels

Aditya Dhananjay, Ashlesh Sharma, Michael Paik, Jay Chen, Trishank Karthik Kuppusamy, Jinyang Li, Lakshminarayanan Subramanian

Research output: Chapter in Book/Report/Conference proceedingConference contribution


While the cellular revolution has made voice connectivity ubiquitous in the developing world, data services are largely absent or are prohibitively expensive. In this paper, we present Hermes 1, a point-to-point data connectivity solution that works by modulating data onto acoustic signals that are sent over a cellular voice call. The main challenge is that most voice codecs greatly distort signals that are not voice-like; furthermore, the backhaul can be highly heterogeneous and of low quality, thereby introducing unpredictable distortions. Hermes modulates data over the extremely narrow-band (approximately 3kHz bandwidth) acoustic carrier, while being severely constrained by the requirement that the resulting sound signals are voice-like, as far as the voice codecs are concerned. Hermes uses a robust data transcoding and modulation scheme to detect and correct errors in the face of bit flips, insertions and deletions; it also adapts the modulation parameters to the observed bit error rate on the actual voice channel. Through real-world experiments, we show that Hermes achieves approximately 1.2 kbps goodput which when compared to SMS, improves throughput by a factor of 5× and reduces the cost-per-byte by over a factor of 50×.

Original languageEnglish (US)
Title of host publicationMobiCom'10 and MobiHoc'10 - Proceedings of the 16th Annual International Conference on Mobile Computing and Networking and 11th ACM International Symposium on Mobile Ad Hoc Networking and Computing
PublisherAssociation for Computing Machinery
Number of pages12
ISBN (Print)9781450301817
StatePublished - 2010
Event16th Annual Conference on Mobile Computing and Networking, MobiCom 2010 - Chicago, IL, United States
Duration: Sep 20 2010Sep 24 2010

Publication series

NameProceedings of the Annual International Conference on Mobile Computing and Networking, MOBICOM


Other16th Annual Conference on Mobile Computing and Networking, MobiCom 2010
Country/TerritoryUnited States
CityChicago, IL

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture
  • Computer Networks and Communications


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