Network Coding for Wireless Sensor Network Storage N. Nguyen*, S. Krishnamurthy**, and D. Jones* Illinois Center for Wireless Systems Model for data storage in a Sensor Network A sensor network is divided into storage zones. Each zone temporarily stores one event-related type of data for querying. Each zone has a manager node that collects data from throughout network and store them in nodes which are members of the zone. A mobile collector can drive by a specific zone to retrieve data from storage nodes We design a distribution scheme to store data in a zone so that data can be recovered reliably. An example data centric sensor network Challenging Issues Asynchronous network: each node has its own schedule Feedback communication could be very time and power expensive. Network coding scheme for data distribution within a zone @ Zone Manager: Encapsulate a packet with a header consisting of all 0’s and only 1 at position corresponding to sequence of the packet in the group (stream of packets is divided into fixed-size groups) Scheme’s robustness Asynchronous property enhances randomness in encoding that increases decoding probability No acknowledgement is needed for communication Redundancy is achieved via exploiting broadcasting nature of wireless sensor nodes @ Storage Node m: Update the current stored packet with newly arrived one after multiplying with a random coefficient (initially, is is zero) @ Collector: - Collect enough number of packets from awake storage nodes (greater than or equal number of packets in a group) - Decode the received packets using Gaussian Elimination Process with inversion matrix formed from packet headers. Test-bed Implementation Test-bed uses 8 tmote sky from Moteiv: 1 mote for zone manager, 1 mote for collector and 6 motes for storage nodes. Group size is 6 * Coordinated Science Laboratory, University of Illinois Urbana-Champaign ** Deutsche Telecom Labs, Germany