Distributed Storage in Wireless Sensor Networks with Network Coding

As part of the Wireless and Sensor Systems (WiSe): Real Time Enterprise project we provide a description of our ongoing research in the area of wireless sensor networks. In general, wireless sensor networks are prone to node failures, unreliable transmission links, interference and buffer overflows. In our project we intend to set up a reliable multi-hop communication for such harsh environments, where the main focus is on data persistence. In order to achieve these goals data redundancy in the network is required. The approach of adding redundancy in wireless networks corresponds to distributed networked storage which is relevant for wireless sensor networks where node failures are not uncommon. For this purpose we consider network coding to store the sensed data in a robust and efficient way, while at the same time minimizing communication costs in the network. Network coding is a technique invented to achieve efficient multicast communication by allowing coding inside the network which means that packets are mixed at the intermediate nodes. This can be viewed as applying encoding operations on the node’s received data from the incoming channels whereas the resulting encoded information is sent over the outgoing channel. At the sink nodes the multicast information is retrieved by decoding the received information. Hence by using distributed storage with network coding we aim to sense the data at the highest possible rates and to reconstruct the information by querying any arbitrary subset nodes of K storage nodes in a network of N storage nodes, where K ≤ N . Note that storage nodes can operate as relay nodes as well. Furthermore we require the datacollector to reconstruct all stored data at the K storage nodes at once with high probability, as long as the sensing rates are inside the network-layer capacity region. A possible application of distributed information storage in wireless sensor networks is environment monitoring and data persistence in a logistical environment.