Abstract-We study the use of Erasure Codes (ECs) for transmitting information from mobile sensor nodes to stationary base stations. In particular, we are interested in improving the overall communication reliability of the wireless communication.Our scenario is wildlife monitoring in which bats are equipped with tiny sensor nodes, just being capable to store a few kB of data and to exchange information over a wireless communication link. This link is used, on the one hand, for determining contact times between individuals. On the other hand, these contacts are communicated in aggregated form to stationary base stations.Since the channel quality may vary quickly due to the continuous movements of bats and the heterogeneous environment, the communication is in general assumed to be highly unreliable. Conventional reliability improving approaches such as full data replication or on-demand retransmission are too expensive or even not possible due to very strict energy constraints and asymmetric channels. ECs allow to enhance the reliability of data transmissions by transmitting redundant data. In this work, we investigate the trade-off between reliability achieved and the cost in form of additional transmissions, i.e., the additional energy costs. Our results clearly show that ECs improve the communication reliability considerably with almost no impact on the resulting delay.

We explore the advantages of using Erasure Codes (ECs) in a very challenging sensor networking scenario, namely, monitoring and tracking bats in the wild. The mobile bat nodes collect contact information that needs to be transmitted to stationary base stations whenever they are in communication range. We are particularly interested in improving the overall communication reliability of the wireless communication. The mobile nodes are capable of storing a few 100kB of data and to exchange contact information in aggregated form. Due to the continuous flight of the bats and the forest environment, the wireless channel quality varies quickly and, thus, the communication is in general assumed to be highly unreliable. Given the very strict energy constraints of the mobile node and the inherently asymmetric channels, conventional techniques such as full data replication or Automatic Repeat Request to improve the communication reliability are prohibitive. In this work, we investigate the tradeoff between reliability achieved and the cost in form of additional transmissions, that is, the additional energy costs. Our energy measurements on a real platform combined with larger-scale simulation of the wireless communication clearly indicate the advantages of using ECs in our scenario. The results are also applicable in other configurations when unreliable communication channels meet tight energy budgets.

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Abstract-We show the feasibility of using Erasure Codes (ECs) for reliable communication in strongly energy-constrained sensor network applications. In particular, we aim at observing group dynamics of bats in their natural habitat. Bats are to be equipped with ultra-light sensor nodes to continuously monitor contacts between each other and to track their flights. This data needs to be uploaded to a stationary ground network whenever a bat comes into communication range. As the quality of this communication link is fluctuating, reliability improvement techniques need to be implemented. ECs allow to enhance the reliability of data transmissions with only a marginal overhead. After showing the improvements using ECs in simulation, we now implemented the full system using a prototype platform to study the general feasibility in a more realistic environment.